Diffraction 2016

2 set 2016, 16:50 → 8 set 2016, 14:30 Europe/Rome

Santa Tecla Palace Hotel, Acireale (Catania, Sicily)

Alessandro Papa (Universita` della Calabria & INFN-Cosenza)

Diffraction 2016 is the ninth biennial Workshop dedicated to theoretical and experimental progress in diffractive processes at high energies. The previous events took place at Cetraro (2000), Alushta (2002), Cala Gonone (2004), Milos (2006), La Londe-les-Maures (2008), Otranto (2010), Lanzarote (2012), Primošten (2014).

Organized and sponsored by:
Istituto Nazionale di Fisica Nucleare (Italy)
Università della Calabria (Italy)

Sito ufficiale

venerdì 2 settembre

17:00 → 19:30 Registration

19:30 → 20:00 Welcome Drink

20:30 → 22:00 Dinner

sabato 3 settembre

08:50 → 09:00 Opening address

08:50 Opening address

Relatore: Alessandro Papa (CS)

Slides Opening.pptx

09:00 → 11:00 Overviews

Coordinatore: Enrico Tassi (CS)

09:00 Recent results and highlights from the ATLAS experiment

After a 2-year stop for the upgrade of the detector, since 2015 the ATLAS collaboration has collected data for over 20 fb-1 at 13 TeV centre-of-mass energy of pp collisions at the LHC. In this talk a summary of recent measurements of Higgs boson properties, BSM Higgs searches and the situation with the resonance at 750 GeV will be presented. Also some of most recent SM and Electroweak results will be highlighted.

Relatore: Davide Caforio (CERN)

Slides Caforio.pdf

09:30 Highlists from CMS

The CMS experiment at the LHC has reported many results on proton-proton and heavy ion collision data at various center-of-mass energies. The talk will highlight a selection of recent results reported by CMS, also presenting a prospect of future results that will be possible with an increased luminosity.

Relatore: Ralf Ulrich (KIT)

Slides Diffraction2016_CMS.pdf

10:00 ALICE latest results in pp, p-Pb and Pb-Pb collisions

The latest ALICE results collected in the pp, p-Pb and Pb-Pb runs at the LHC are presented. The energy evolution of the main observables describing the features of the heavy ion interaction at high energies is discussed: J/psi suppression, fluid hydrodynamics and hard probes are shedding light on the properties of the matter in the high temperature nuclear fireball created at energies up to √sNN=5.02 TeV. In addition, smaller collision systems (pp or p-Pb) look hotter than expected, showing few interesting cumulative effects. In the next p-Pb run, ALICE will continue to search for gluon saturation in the proton at higher energies, with the photon-proton centre of mass energy exceeding 1 TeV. A short description of the forthcoming ALICE upgrades will be presented.

Relatore: Eugenio Scapparone (BO)

Slides diffraction_2016_ES_3.pptx

10:30 Recent progress in theoretical predictions for LHC physics

The talk will review recent progress in perturbative calculations within the Standard Model (QCD and electroweak sectors) for hadronic collisions, including reference to their implementation in simulation tools. The impact on the run 2 LHC physics programme will be discussed as well.

Relatore: Fulvio Piccinini (PV)

Slides piccinini.pdf

11:00 → 11:30 Coffee break

11:30 → 12:30 Future machines

Coordinatore: Marcella Capua (CS)

11:30 Diffraction at the future Electron-Ion Collider

The 2015 nuclear physics long-range plan endorsed the realization of an electron-ion collider as the next large construction project after FRIB. eRHIC, the Brookhaven realization of the electron-ion collider with its high luminosity ($> 10^{33} cm^{-2}s^{-1}$), wide kinematic reach in center-of-mass-energy (45 GeV to 145 GeV) and high lepton and proton beam polarization provides an unprecedented opportunity to reach new frontiers in our understanding of the spin and dynamic structure of nucleons. This presentation will highlight several key measurements which will provide definite answers to the following questions: How are the sea quarks and gluons, and their spins, distributed in space and momentum inside the nucleon? How are these quark and gluon distributions correlated with overall nucleon properties, such as spin direction? What is the role of the orbital motion of sea quarks and gluons in building up the nucleon spin?

Relatore: Salvatore Fazio (Brookhaven National Laboratory)

Slides Fazio_DIFFRACTION2016_v4.pptx

12:00 Jefferson Lab EIC (JLEIC) and Diffractive Physics

The Electron-Ion Collider (EIC) is a project in the US aiming for start of physics in the mid-2020's. Jefferson Lab EIC (JLEIC) is one of the two proposed realization of the EIC and would use the existing 12 GeV CEBAF accelerator as a full energy injector. Attention has been paid to optimize the JLEIC accelerator, interaction region, and detector concepts for EIC physics measurements. I will describe the JLEIC design, with particular emphasis on diffractive measurements and forward detectors.

Relatore: Rikutaro Yoshida (JLab)

Slides Yoshida.pdf Yoshida.pptx

12:30 → 13:30 Diffraction in ep collisions (I)

Coordinatore: Prof. Douglas Ross (Southampton University)

12:30 MMHT2014 PDFs -- updates

Updates of MMHT2014 global parton analysis. Discussion includes the determination of alpha_s, the heavy b,c quarks and their masses, inclusion of the combined HERA data and the impact of recent LHC data.

Relatore: Alan Martin (IPPP, Durham University)

Slides Martin.pdf

12:50 xFitter

An accurate knowledge of the Parton Distribution Functions (PDF) plays a critical role for the precision tests of the Standard Model (SM) and impact substantially the theory predictions of Beyond SM high mass production. We present the xFitter project (former HERAFitter) which provides a unique open-source software framework for the determination of the proton's PDFs and for the interpretation of the physics analyses in the context of Quantum Chromodynamics. We highlight the new xFitter software release which includes many new features and additions, e.g. the possibility of the inclusion of photon PDF updated variable and fixed-flavour schemes for heavy quarks, interface to the APFEL library and n-space evolution program MELA, updates to the latest theory calculations, fast grid tools and many more. We will also give examples of physics studies which have used xFitter and report on the latest xFitter results on the new determination of the mass of the charm quark extracted by analysing the statistical quality of fits to inclusive and exclusive charm deep-inelastic scattering data from the HERA collider. We employ the running mass definition in the MSbar scheme, which improves the perturbative stability as compared to the pole-mass definition, in the framework of the FONLL general-mass scheme.

Relatore: Amanda Cooper-Sarkar (Univ. Oxford)

Slides xFitter.pptx

13:10 Charm in the Proton

We review the factorisation of deep inelastic processes with charm quarks, and the construction of variable-flavour-number schemes, both with and without an intrinsic charm PDF. Results are then presented of the latest NNPDF fits, both with and without intrinsic charm. The dependence of the PDFs on the charm mass is discussed.

Relatore: Richard Ball (CERN)

Slides RDB_Diffraction_16.pdf

13:30 → 16:00 Lunch and leisure time

16:00 → 17:40 Diffraction in ep collisions (II)

Coordinatore: Marta Ruspa (TO)

16:00 Novel approach to non-perturbative inputs for parton distributions

Parton distributions in hadrons are usually constructed in the framework of QCD factorization in terms of convolutions of perturbative contributions and non-perturbative inputs. We study such inputs for gluon and quark distributions in both polarized and non-polarized hadrons. First, we derive general restrictions on the inputs following from the requirement of convergence of the factorization convolutions. Then we use those restrictions as criteria for modeling the inputs and propose the Resonance Model for them. Our model is based on the simple reasoning: After emitting an active parton off the colliding hadron, the ensemble of remaining partons (spectators) becomes unstable, so it can be expressed in terms of resonances.

Relatore: Boris Ermolaev (Ioffe Physico-Technical Institute)

Slides Ermolaev.pdf

16:20 Combined H1 and ZEUS inclusive data and QCD fits

A combination of all inclusive deep inelastic cross sections published by the H1 and ZEUS collaborations at HERA-I and HERA-II, for neutral and charged current e^{\pm} P scattering, is presented. This supersedes the combination of HERA-I data published in 2010. The combined cross sections were input to QCD analyses at LO, NLO and NNLO in order to extract new parton distribution functions (PDFs) called HERAPDF2.0. The analysis was extended by including HERA data on charm production and jet production. This made a simultaneous extraction of the PDFs and the strong coupling parameter possible at NLO, resulting in the value: \alpha_s(M_Z) =0.1183 \pm 0.0009(exp) \pm 0.0005(model/param.) \pm 0.0012(hadronisation) +0.0037/-0.0030(scale).

Relatore: Amanda Cooper-Sarkar (Univ. Oxford)

Slides herapdf20_short.pptx

16:40 QCD and electroweak fits from H1 and from ZEUS

The H1 and ZEUS collaborations used inclusive deep inelastic scattering cros s sections measured at HERA to probe electroweak parameters of the Standard Model. The cross sections were determined using longitudinally polarised lepton bea ms. A simultaneous fit of parton distribution functions and electroweak para meters to HERA data on DIS is presented. Results on the vector and axial-vec tor couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the masses of the W and Z bosons are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.

Relatore: Katarzyna Wichmann (DESY)

Slides Wichmann.pdf

17:00 Measurement of Tagged Deep Inelastic Scattering in Hall A of Jefferson Lab

A tagged deep inelastic scattering experiment is planned in Hall A of Jefferson Lab, in which the mesonic content of the nucleon will be probed directly. The experiment will measure low momentum recoiling (and spectator) protons in coincidence with deeply inelastically scattered electrons from hydrogen (and deuterium) targets, covering kinematics of 8 < W^2 < 18GeV^2, 1 < Q^2 < 3(GeV/c)^2 and 0.05 < x < 0.2. The tagging technique will enhance deep inelastic scattering from partons in the meson cloud and provide access to the pion structure function via the Sullivan process. The setup will utilise a 50μA, 11GeV electron beam incident upon a gaseous target. The target will be either hydrogen or deuterium, to measure either charged or neutral pion cloud. The target will be surrounded by a GEM-based radial time projection chamber (RTPC), having a length of 400mm and a radius of 15cm, and optimized for measuring protons spanning momenta of 60-400MeV/c. A solenoid magnet will encapsulate both the RTPC and the target. The Hall A Super BigBite spectrometer will be used to measure the scattered electrons. An overview of the measurement, experimental setup, simulations and projected results will be given.

Relatore: Rachel Montgomery (University of Glasgow)

Slides Montgomery_TDIS_Diffraction_030916.pdf

17:20 Relating nucleon total cross sections to DIS structure functions

High-energy nuclei total cross sections are related to low-x DIS structure functions by using the additive quark model. Manifestation of saturation effects in NN and ep cross sections is discussed.

Relatore: Laszlo Jenkovszky (Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine)

Slides Jenkovszky.pptx

17:40 → 18:10 Coffee break

18:10 → 19:30 Diffraction in ep collisions (III)

Coordinatore: Marta Ruspa (TO)

18:10 Fitting the Discrete BFKL Pomeron to HERA DIS Data at Low-x

The modification of the BFKL formalism which leads to a discrete spectrum of Regge poles relies on the imposition of specific phases for the oscillatory behaviour at some small gluon transverse momentum We show that the resulting unintegrated gluon density is very sensitive to the choice of such phases and demonstrate that by taking a particular ansatz for these phases it is possible to fit the high-quality HERA data for structure functions but only for x < 0.001.

Relatore: Douglas Ross (Southampton University)

Slides poles.wmv ross.pdf

18:30 The color dipole picture

We summarize the essentials of the color dipole picture applied to electron-nucleon deep inelastic scattering, heavy vector meson production and ultra-high energy cosmic neutrino scattering.

Relatore: Dieter Schildknecht (Bielefeld University)

Slides Acireale2016.pdf

18:50 Diffractive Dijet Production in the Color Glass Condensate

I will talk about exclusive dijet production in coherent diffractive processes in deep inelastic scattering and real (and virtual) photon-hadron collisions in the Color Glass Condensate formalism. Ref: arXiv:1511.07452.

Relatore: Amir Rezaeian (Santa Maria Universidad)

Slides diff2016_AR.pdf

19:10 Impact factor for exclusive diffractive dijet production with NLO accuracy

We will present the computation of the virtual correction to the impact factor for the diffractive production of an open quark-antiquark pair using Balitsky's shockwave formalism, and by adding the corresponding real contribution we will build a finite impact factor for the exclusive diffractive production of a dijet with NLO accuracy.

Relatore: Renaud Boussarie (LPT Orsay)

Slides BoussarieDiffraction2016.pdf

20:30 → 22:00 Dinner

domenica 4 settembre

09:00 → 10:55 Spin Physics (I)

Coordinatore: Mauro Anselmino (TO)

09:00 Recent results of the high-energy spin physics program at RHIC at BNL

High energy polarized $p+p$ collisions at $\sqrt{s}=200-500\,$GeV at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) provide a unique way to probe the proton spin structure and dynamics using hard scattering processes. The production of jets and hadrons is the prime focus of gluon polarization studies. The production of $W^{-(+)}$ bosons at $\sqrt{s}=500\,$GeV provides an ideal tool to study the spin-flavor structure of the proton. Various measurements on the study of transverse spin effects have been performed. Recent results will be presented followed by a brief outlook of future spin physics opportunities at RHIC and an Electron-Ion Collider facility.

Relatore: Bernd Surrow (Temple University)

Slides BSurrow-Diffraction2016.pdf

09:25 Transverse single-spin asymmetry of weak boson, Drell-Yan and prompt photon production in p+p collisions at STAR

Accessing the Sivers TMD function in proton+proton collisions through the measurement of transverse single spin asymmetries (TSSAs) in Drell-Yan and weak boson production is an effective path to test the fundamental QCD prediction of the non-universality of the Sivers function. Furthermore, it provides data to study the spin-flavor structure of valence and sea quarks inside the proton and to test the TMD evolution of parton distributions. The TSSA amplitude, $A_{N}$, has been measured at STAR in proton+proton collisions at $\sqrt{s} = 500$~GeV, with a recorded integrated luminosity of $25~\text{pb}^{-1}$. Within relatively large statistical uncertainties, the current data favor theoretical models that include a change of sign for the Sivers function relative to observations in SIDIS measurements, if TMD evolution effects on the $A_{N}$ are small. RHIC plans to run collisions of transversely polarized proton+proton beams at $\sqrt{s} = 510$~GeV in 2017, delivering an integrated luminosity of $400~\text{pb}^{-1}$. This will allow STAR to perform a precise measurement of TSSAs in both Drell-Yan and weak boson production. The present status and future plans for the Sivers function program at STAR will be discussed as well as other observables sensitive to the non-universality of the Sivers function via the Twist-3 formalism, e.g. the TSSA of prompt photons.

Relatore: Salvatore Fazio (Brookhaven National Laboratory)

Slides Fazio_STAR_DIFFRACTION2016_v3.pptx

09:45 PHENIX recent results from polarized pp and pA collisions

We summarize the recent results from polarized pp and pA collisions in PHENIX at RHIC. Measurements in high energy longitudinally polarized proton collisions allow us to get access to the contribution of gluon and flavor separated (anti-)quark polarization to the spin of the proton. Measurements with transversely polarized protons help our understanding of parton dynamics within hadrons and test the fundamentals of color interactions in hadronic reactions. First ever data from collisions of polarized protons on nuclei at RHIC in 2015 opened new avenue in both spin and heavy ion physics. We discuss the first intriguing results on nuclear size dependence of transverse spin asymmetry in forward neutron production in pA collisions.

Relatore: Alexander Bazilevsky (Brookhaven National Laboratory)

Slides Bazilevsky.pdf

10:10 Single-spin asymmetry of leading neutrons in polarized pA collisions

Mild nuclear effects are predicted for the production cross section and single-spin asymmetry of leading neutrons, in reaction pA=>nX with polarized protons. This result does not contradict the anomalously large asymmetry observed by PHENIX in large rapidity-gap events.

Relatore: Boris Kopeliovich (UTFSM)

Slides kopeliovich.pdf

10:35 New developements in the statistical approach of parton distributions: tests and predictions up to LHC energies

The quantum statistical parton distributions approach proposed more than one decade ago is revisited by considering a larger set of recent and accurate Deep Inelastic Scattering experimental results. It enables us to improve the description of the data by means of a new determination of the parton distributions. This global next-to-leading order QCD analysis leads to a good description of several structure functions, involving unpolarized parton distributions and helicity distributions, in a broad range of $x$ and $Q^2$ and in terms of a rather small number of free parameters. There are several challenging issues,in particular the behavior of $\bar d /\bar u$ at large $x$, a possible large positive gluon helicity distribution, etc . The predictions of this theoretical approach will be tested for single-jet production and charge asymmetry in $W^{\pm}$ production in $\bar p p$ and $p p$ collisions up to LHC energies, using recent data and also for forthcoming experimental results.

Relatore: Jacques Soffer (Temple University, Philadelphia, PA, USA)

Slides diffraction2016-soffer.pdf

10:55 → 11:10 Coffee break

11:10 → 13:30 Spin Physics (II)

Coordinatore: Prof. Jacques Soffer (Temple University, Philadelphia, PA, USA)

11:10 The Quest for the Origin of the Proton’s Sea

The proton is a composite particle in which the binding force is responsible for the majority of its mass. To understand this structure, the distributions and origins of the quark-antiquark pairs produced by the strong force must be measured. The SeaQuest collaboration is using the Drell-Yan process to elucidate antiquark distributions in the proton and to study the modification of these distributions when the proton is held within a nucleus. Preliminary results based on a fraction of the anticipated final data set will be presented.

Relatore: Paul E Reimer (Argonne National Laboratory)

Slides 2016ReimerSeaQuestDiffraction.pdf

11:35 Low-x gluon TMDs, the dipole picture and diffraction

We discuss the momentum distributions of gluons and consider the dependence of the gluon parton distribution functions (PDFs) on both fractional (longitudinal) momentum x and transverse momentum pT, referred to as the gluon TMDs. Looking at the operator structure of the TMDs, we are able to unify various descriptions at small-x including the dipole picture and the notions of pomeron and odderon exchange. We study the structure of gluon TMDs for unpolarized, vector polarized and tensor polarized targets.

Relatore: Piet Mulders (Nikhef Theory Group and VU)

Slides 2016-diffraction16-Mulders.pdf 2016-diffraction16-Mulders.pptx

12:00 The 3D nucleon structure in momentum space

The Transverse Momentum Dependent Partonic Distributions (TMD-PDFs) and Fragmentation Functions (TMD-FFs) should reveal new properties of the 3-dimensional structure of nucleons and of the quark hadronization process. Many experimental data are now available, much progress has been made in their phenomenological interpretation, future facilities and experiments are being planned. A short summary of the situation is presented.

Relatore: Mauro Anselmino (TO)

Slides Diffraction-2016.pdf

12:25 Recent Results of the Jefferson Lab SANE experiment

The Spin Asymmetries of the Nucleon Experiment (SANE) ran at Jefferson Lab and measured double spin asymmetries for inclusive electron scattering on a proton target which was polarized parallel and perpendicular to the polarized electron beam. SANE used a large acceptance detector package to measured the proton's polarized spin structure functions $g_1$ and $g_2$ in a range of Bjorken $x$, $0.3 < x < 0.8$, and a range of $Q^2$ from to $1.8 GeV^2$ up to $6.5 GeV^2$. Complementary measurements were made simulataneously with the standard Hall C small acceptance High Momentum Spectrometer. Within the operator product expansion framework, the twist-3 matrix element, $d_2^p=\int x^2(2g_1+3g_2)dx$, is proportional to the average color Lorentz force on the quark (moving in the infinite momentum frame) the instant after being struck by a virtual photon. In addition to presenting the latest results on spin structure functions, we will discuss the physics impact and Q$^2$ dependence of $d_2^p$.

Relatore: Mark Jones (Jefferson Lab)

Slides Diffraction-mkjones.pdf

12:50 Quark angular and transverse momentum in covariant approach

We study the covariant version of the quark-parton model in which intrinsic 3D motion of quarks is consistently taken into account. Covariant kinematics combined with rotational symmetry of the quark momentum distribution in the nucleon rest frame generate new relations and constraints. In this way the predictions concerning TMDs, quark angular momentum or proton spin content have been done and will be presented. A possible algorithm for QCD evolution of TMDs will be suggested. P.Z., Phys. Rev. D 89, 014012 (2014), Phys. Lett. B 751, 525 (2015). A.Efremov, O.Teryaev and P.Z., J.Phys.Conf.Ser. 678 (2016) no.1, 012001, arXiv:1511.01164.

Relatore: Petr Zavada (Institute of Physics, ASCR, Prague)

Slides zavada_diff16.pdf

13:10 Extraction of Generalized Parton Distributions from Deeply Virtual Compton Scattering Data

We review various procedures for extraction of GPDs from DVCS data, especially in the light of new 2015 measurements by CLAS and Hall A JLab collaborations.

Relatore: Kresimir Kumericki (University of Zagreb)

Slides kumericki-acireale16.pdf

13:30 → 16:00 Lunch and leisure time

16:00 → 17:20 Diffraction in ep collisions (IV)

Coordinatore: Prof. Douglas Ross (Southampton University)

16:00 Hard QCD and the hadronic final state at HERA

The production of inclusive jets, dijets and trijets was investigated with the high statistics HERA II DIS data. The H1 experiment have determined the corresponding cross sections with improved experimental precision and sophisticated method of unfolding, compared to previous measurements. The results were compared with NLO QCD calculations. Signals of QCD instanton-induced processes were searched for in neutral current deep-inelastic scattering with high momentum transfer Q2 by H1 collaboration. Compared to earlier publications, the limits were improved by an order of magnitude and for the first time were challenging predictions. Measurements with the ZEUS data in DIS of isolated photons were reported, including studies of kinematic variables sensitive to the event dynamics. The measurements were compared to MC models and to theoretical calculations of Baranov-Lipatov –Zotov based on kt factorisation QCD approach.

Relatore: Alice Valkarova (Charles University Prague)

Slides Valkarova.pdf

16:20 Hard diffraction and factorisation breaking

Recent results are presented on diffractive dissociation in deep inelastic scattering and photoproduction from HERA. Reviews of measurements of final states containing jets, D* meson and photons are used to address the issue of validity of hard QCD factorization commonly used to predict cross section and differential shapes by means of using diffractive parton densities obtained from previous QCD fits of inclusive diffractive data. A measurement is also presented of exclusive diffractive dijet production confronted with predictions based on hard factorization and two gluon exchange model examined in the lepton-dijet production planes' angular distribution.

Relatore: Karel Cerny (Charles University Prague)

Slides Cerny.pdf

16:40 Vector meson production at HERA

Latest H1 and ZEUS results on vector meson production at HERA are presented. Exclusive rho0 photoproduction with a leading neutron and the cross section ratio psi'/psi in deep inelastic scattering are discussed in detail.

Relatore: Ada Maria Solano (TO)

Slides Solano-DIFFR16.pdf

17:00 Predictions for diffractive $\phi$ meson production using AdS/QCD light-front wavefunction.

We compute the rate for diffractive $\phi$ electro-production within the Color Glass Condensate model. The model parameters are obtained from fits to the most recent combined HERA data on inclusive deep inelastic scattering. As for the $\phi$ meson, we use the holographic light front wavefunction obtained from AdS/QCD. Our predictions are compared with the available data collected at the HERA collider.

Relatore: Mohammad Ahmady (Mount Allison University)

Slides DIFF_2016.pdf

17:20 → 17:50 Coffee break

17:50 → 18:30 Diffraction in ep collisions (V)

Coordinatore: Prof. Douglas Ross (Southampton University)

17:50 The growth with energy of exclusive J/Psi and Upsilon photo-production cross-sections and BFKL evolution

We investigate whether NLO BFKL evolution is capable to describe the energy dependence of the exclusive photo-production cross-section of vector mesons J/Psi and Upsilon on protons. Our description is based on available NLO BFKL fits of the proton impact factor in inclusive DIS, which allow us to construct the necessary scattering amplitude at zero momentum transfer t=0. Assuming an exponential drop-off with t, this result allows us to calculate the exclusive photoproduction cross-section. Comparing our results with both HERA data (measured by H1 and ZEUS collaborations in ep collision) and LHC data (measured by ALICE, CMS and LHCb collaborations in ultra-peripheral pp and pPb collision) we find that our framework provides a very good description of the energy dependence of the J/Psi and Upsilon photoproduction cross-section, providing therefore further evidence for BFKL evolution at the LHC. The available fits of the proton impact factor require on the other hand an adjustment in the overall normalization.

Relatore: Martin Hentschinski (Benemérita Universidad Autónoma de Puebla & ICN UNAM)

Slides diffraction_2016_MH.pdf

18:10 The Pomeron ground state and its decays to light mesons and photons

The problem of the timelike Pomeron coupling to light mesons and photons is considered in light of the available data on high-energy meson-proton and gamma-proton scattering. Possible correspondence of f2(1950) resonance to the Pomeron ground state is argued.

Relatore: Anton Godizov (Institute for High Energy Physics, Protvino)

Slides prescat.pdf

18:30 → 19:50 Diffraction in hadron-hadron collisions - experiment (I)

Coordinatore: Prof. Risto Orava (Helsinki Inst. of Physics and Univ. of Helsinki, CERN)

18:30 Diffraction measurements using LHC Beam Loss Monitoring system

The beam losses in the Large Hadron Collider (LHC) are monitored with an array of detectors spread around the ring. The main function of the Beam Loss Monitoring (BLM) system is to protect the machine elements from beam losses that could cause damage to them. We will present the BLM system and discuss its capabilities and limitations in diffractive event detection, main focus being in the CEP event analysis.

Relatore: Matti Kalliokoski (CERN)

Slides Diffraction_Measurements_with_BLM.pptx

18:50 Observables of QCD diffraction

We will discuss measurability of soft QCD processes, especially high energy pp-diffraction. Future progress on this subject depends heavily on more precise definitions of physical observables, both experiment and theory wise.

Relatore: Mikael Mieskolainen (Helsinki Institute of Physics, University of Helsinki)

Slides mikaelm

19:10 Exclusive diffractive resonance production in proton-proton collisions at the LHC

A model for exclusive diffractive resonance production in proton-proton collisions at the LHC is presented. Cross sections are calculated by folding the Pomeron-Pomeron total cross section (*) with the Donnachie-Landshoff parameterisation of the Pomeron flux in the proton(**). The single differential cross section dsigma/dM as well as the double differential cross section dsigma/dMdp_T will be shown for the resonances f0(980) and f2(1270). The range of x-values of the Pomeron flux accessible in these measurements will be addressed. *) R.Fiore, L.Jenkovszky, R.Schicker, Resonance production in Pomeron-Pomeron collisions at the LHC, Eur. Phys. J. C76 (2016) 1, 38 **) A.Donnachie, P.V.Landshoff, Hard diffraction: Production of high p_T jets, W or Z, and Drell-Yan pairs, Nucl. Phys. B303 (1988), 634

Relatore: Rainer Schicker (Phys. Inst., University Heidelberg)

Slides Schicker.pdf

20:30 → 22:00 Dinner

lunedì 5 settembre

09:00 → 10:40 Progress in QCD (I)

Coordinatore: Dr. Dmitry Ivanov (Sobolev Institute of Mathematics)

09:00 Euler-Lagrange equations for effective actions in QCD and gravity at high energies

The high energy asymptotics of scattering amplitudes in QCD is formulated in terms of reggeized gluons and their interactions. I remind the functional approach for the calculation of various reggeon vertices. The Euler-Lagrange equations for the corresponding effective action allows to find the reggeon field theory in QCD in tree approximation. The simplest composite state of Reggeized gluons is BFKL Pomeron. In N=4 SUSY it is dual to the reggeized graviton living in 10-dimensional anti-de-Sitter space. We construct generally covariant action describing the interaction of the usual and reggeized gravitons. The Euler-Lagrage equations for this action are derived and their properties are discussed.

Relatore: Lev Lipatov (Petersburg Nuclear Physics Institute)

Slides Lipatov.pdf

09:20 Reggeon field theory as an effective theory for QCD at high energies

Based upon an analysis of the renormalization flow equations we analyse the fixed point structure and derive a new scaling law solution. Particular emphasis is given to the transverse extension of the scattering amplitude.

Relatore: Joachim Bartels (University Hamburg)

Slides Bartels.pdf

09:40 Peculiarities of the BFKL approach in the NNLLA

Peculiar properties of the BFKL approach in the next-to-next-to-leading logarithmic approximation are discussed. In this approximation the scheme of derivation of the BFKL equation must be changed because of violation of the simple factorized form of amplitudes with multi-reggeon exchanges.

Relatore: Victor Fadin (Institute of Nuclear Physics SB RAS)

Slides Fadin.pdf

10:00 Pomeron-Odderon interactions: a functional RG flow analysis

An effective field theory for interacting pomeron and odderon fields is studied non perturbatively analysing the flow of the effective average action. We present some preliminary results on the critical structure associated to the fixed points of the flow.

Relatore: Gian Paolo Vacca (BO)

Slides Vacca.pdf

10:20 Di-hadron production at LHC: BFKL predictions for cross sections and azimuthal correlations

A study of the inclusive production of a pair of hadrons (a “di-hadron” system), having high transverse momenta and separated by a large interval of rapidity, is presented. This process has much in common with the widely discussed Mueller-Navelet jet production and can be also used to access the BFKL dynamics at proton colliders. Large contributions enhanced by logarithms of energy can be resummed in perturbation theory within the BFKL formalism with next-to-leading logarithmic accuracy. The experimental study of di-hadron production would provide with an additional clear channel to test the BFKL dynamics. The first theoretical predictions for cross sections and azimuthal angle correlations of the di-hadrons produced with LHC kinematics are presented.

Relatore: Francesco Giovanni Celiberto (CS)

Slides talk_Diffraction_2016_di-hadron_Celiberto.pdf

10:40 → 11:10 Coffee break

11:10 → 12:30 Progress in QCD (II)

Coordinatore: Dr. Dmitry Ivanov (Sobolev Institute of Mathematics)

11:10 Holographic meson Distribution Amplitudes

Light-front holography, pioneered by Brodsky and de Teramond in the last decade, is an exact correspondence between a semiclassical approximation of light-front QCD and classical gravity in a higher dimensional anti-de Sitter space. Light-front holography predicts analytical forms for meson light-front wavefunctions which are essential to compute, amongst other processes, diffractive vector meson production at HERA and the LHC. This allows testing of the holographic light-front wave functions against experimental data. It is equally important to compare the predictions of light-front holography to those of other more traditional non-perturbative methods like lattice QCD, QCD Sum Rules and Dyson-Schwinger equations equations. The latter methods are able to predict the Distribution Amplitudes which are related to the holographic light-front wave functions. Here, we compare the predictions of light-front holography and the traditional non-perturbative methods for the Distribution Amplitudes of mesons.

Relatore: Ruben Sandapen (Acadia University)

Slides RSandapenDiff2016__.pdf

11:30 Unintegrated double parton distributions

The construction of the unintegrated double parton distribution functions which include additional dependence on transverse momenta is presented. The theoretical framework is an extension of the previous formulation which was used to obtain the single unintegrated parton distribution functions from the standard integrated parton densities. Starting from the DGLAP-like evolution equations for the integrated double parton distributions, the homogeneous part of the unintegrated double parton distribution functions are defined through the convolutions of the integrated double distributions with the appropriate splitting functions and the product with the Sudakov form factors. It is shown that there are three domains of external scales which require three distinct forms of these unintegrated densities. The ensuing correlations in the longitudinal momenta is also dicussed as well as to the unintegrated double parton distributions from the non-homogenous term which corresponds to the splitting of a single parton into daughter partons with high transverse momenta.

Relatore: Krzysztof Golec-Biernat (Institute of Nuclear Physics PAN)

Slides golec.pdf

11:50 Inclusive heavy flavour production in the dipole picture

I report on recent results for heavy flavour (b,c-jets as well as open heavy flavour) production processes in the dipole picture and their relation to those in kT-factorisation. B-jet and B-meson transverse momentum and rapidity distributions are compared to the recent LHC data for several models of unintegrated gluon distributions in the target proton.

Relatore: Roman Pasechnik (Lund University)

Slides Acireale-HF.pdf

12:10 Exclusive photoproduction of a gamma rho pair with a large invariant mass

Exclusive photoproduction of a gamma rho pair in the kinematics where the pair has a large invariant mass and the final nucleon has a small transverse momentum is described in the collinear factorization framework. The scattering amplitude is calculated at leading order in alphaS and the differential cross sections for the process where the rho-meson is either longitudinally or transversely polarized are estimated in the kinematics of the JLab experiments.

Relatore: Samuel Wallon (LPT Orsay)

Slides Wallon-DIFF-2016rho.pdf

12:30 → 14:00 Lunch and leisure time

14:00 → 20:00 Excursion

20:30 → 22:00 Dinner

martedì 6 settembre

09:00 → 11:00 Diffraction in hadron-hadron collisions - experiment (II)

Coordinatore: Christina Mesropian (Rockefeller University)

09:00 The results of the TOTEM experiment

The TOTEM experiment at the LHC has measured proton-proton elastic scattering in dedicated runs at \sqrt{s}=7 and 8 TeV centre-of-mass LHC energies. The proton-proton total cross-section \sigma_{tot} has been derived for both energies using a luminosity independent method. TOTEM has excluded a purely exponential differential cross-section for elastic proton-proton scattering with significance greater than 7\sigma in the |t| range from 0.027 to 0.2 GeV^{2} at \sqrt{s}=8 TeV. The TOTEM experiment measured elastic scattering at \sqrt{s}=8 TeV in the Coulomb-Nuclear Interference Region. TOTEM has also measured diffractive scattering at \sqrt{s}=7 and 8 TeV in different event topologies.

Relatore: Frigyes Nemes (CERN)

Slides Diffraction_2016_Acireale_Italy_Frigyes_Nemes_2.pdf

09:30 Measurements of total pp cross sections at 8 TeV and 13 TeV with the ATLAS detector

The total pp cross section is a fundamental property of the strong interaction which can not be calculated in perturbative QCD but only described based on phenomenological models. The ATLAS collaboration has recently measured the total inelastic protonproton cross section and the diffractive part of the inelastic cross section at 13 TeV in special data sets taken with low beam currents and using forward scintillators. A more precise measurement of the total pp cross section as well as elastic and inelastic contributions can be extracted from a measurement of the differential elastic cross section using the optical theorem. The ATLAS Collaboration has collected 0.5 /nb of elastic data in a dedicated run with high beta* optics at 8 TeV centreofmass energy with the ALFA Roman Pot detector in order to perform this measurement. From the extrapolation of the differential elastic cross section to t=0, using the optical theorem, the total cross section is extracted with the luminositydependent method with unprecedented precision. In addition the nuclear slope of the elastic tspectrum and the total elastic and inelastic cross sections are determined.

Relatore: Hasko Stenzel (ATLAS)

Slides Stenzel.pdf

09:50 CMS results on soft and hard diffraction

The measurement of the soft diffractive cross sections in single- and double-diffractive final states is presented at 7 TeV. Furthermore, also the production of jet-gap-get final states is discussed and the results are interpreted in terms of a hard color singlet exchange. Finally, general features of particle production also in single-diffractive enhanced events are shown at 13TeV.

Relatore: Maria Margherita Obertino (Universita' del Piemonte Orientale)

Slides DiffractionAtCMS_Obertino_v5c.pdf

10:10 Measurements of identified particle spectra in diffractive $pp$ collisions with the STAR detector at RHIC

We present the diffractive program with the STAR Roman Pot detectors at RHIC, focusing on the spectra of identified charged particles as pions, kaons and protons and their anti-particle counterparts in Single Diffraction $(p+p\to p+X)$ and Central Diffraction $(p+p\to p+X+p)$ processes. The final state proton(s) were tagged in the STAR Roman Pot system while the identified charged particle tracks were reconstructed in the STAR Time Projection Chamber (TPC). Ionization energy loss and time-of-flight of charged particles was used for particle identification. Moreover, the proton–anti-proton production asymmetry as a function of rapidity is presented to study the baryon number transfer over a large space in rapidity in single diffraction. Similar effect has been studied in proton-proton and proton-photon interactions but it is the first measurement in proton-Pomeron collision. In addition, the present status and future plans of the diffractive physics measurements at RHIC is described.

Relatore: Lukasz Fulek (AGH UST)

Slides Diffraction2016_Fulek.pdf

10:30 Hadronic Interaction Model Calibration with LHCf data at LHC

The LHCf experiment is aimed to provide precise measurements of the spectra of neutral particles produced in the very forward region at LHC. These measurements provide a calibration tool to tune the hadronic interaction models used by groundbased cosmic rays experiments up to the highest energy currently available at accelerator facilities and are hence of fundamental importance to interpret the EAS results in terms of primary cosmic ray properties. In order to achieve this goal, LHCf makes use of two small sampling calorimeters installed at ±140m from LHC IP1, so that it can detect neutral particles produced by p-p collisions having pseudo-rapidity η > 8.4. LHCf has taken data in p-p collisions at different energies (√s = 0.9 TeV, 2.76 TeV, 7 TeV and 13 TeV) and in p-Pb collisions (√sNN = 5.02 TeV). In this talk, a summary of the main results achieved by the Collaboration will be given showing the comparison with Monte Carlo model predictions with particular emphasis to the π0 spectra which offer the possibility to study pT and pz spectra, to test Feynman scaling hypothesis and to estimate the nuclear modification factor.

Relatore: Alessia Rita Tricomi (CT)

Slides Diffraction16.pdf

11:00 → 11:20 Coffee break

11:20 → 13:30 Diffraction in hadron-hadron collisions - experiment (III)

Coordinatore: Prof. Risto Orava (Helsinki Inst. of Physics and Univ. of Helsinki, CERN)

11:20 Hadron Spectroscopy in Double Pomeron Exchange Experiments : a Review

Central exclusive production in hadron-hadron collisions at high energies, for example p + p → p + X + p where the + represents a large rapidity gap, is a valuable process for spectroscopy of mesonic states X. At collider energies the gaps can be large enough to be dominated by pomeron exchange, and then the quantum numbers of state X are limited. Isoscalar JPC = 0++ and 2++ mesons are selected, and our understanding of these spectra is incomplete. In particular, soft pomeron exchanges favor gluon-dominated states such as glueballs, not yet well established. I will review the published data.

Relatore: Michael Albrow Albrow (Fermilab)

Slides Diff2016_Albrow.pptx

11:50 Measurements of diffractive and exclusive processes with ATLAS

The ATLAS collaboration has carried out a study of diffractive dijet production at 7 TeV pp collisions at the LHC, i.e. events with a hadronic system containing at least two jets in addition to a large region of pseudorapidity devoid of hadronic activity. The data distributions are compared with Monte Carlo models and the rapidity gap survival probability has been estimated in the kinematic region with high diffractive contribution. In the absence of forward proton tagging, exclusive processes can be distinguished in the central part of the ATLAS detector exploiting the large rapidity gap in the central region and the absence of charged particles reconstructed in the inner tracking detector. This strategy has been exploited to study the exclusive production of dilepton pairs in the data taken at centreofmass energies of 7 and 8 TeV. The 7 TeV study concentrates on a precision measurement of the dielectron and dimuon process, while the 8 TeV measurement explores the exclusive production of WW pairs in the electronmuon channel. Prospects for exclusive jet production studies with the forward proton tagging capability of the AFP subdetector of ATLAS will be discussed. A first look at data taken jointly with the ATLAS and LHCf detectors in a p+Pb run will also be shown.

Relatore: Mateusz Dyndal (ATLAS)

Slides Dyndal.pdf

12:10 Exclusive central pi^+pi^- production in proton-proton collisions at ps = 7 TeV

We report a measurement of the exclusive production of pairs of charged pions in proton-proton collisions, dominated by the process pp->p(*)pi^+pi^-p(*), where p(*) stands for a diffractively dissociated proton, the p+p- pair is emitted at central rapidities y, and the incident protons stay intact or dissociate without detection p(*). The measurement is performed with the CMS detector at the LHC, using a data sample corresponding to an integrated luminosity of 450 ub^-1 collected at a center-of-mass energy of 7 TeV in 2010. The cross section measured in the phase space defined by pion transverse momentum pT > 0.2 GeV/c and rapidity jyj < 2 is found to be 20.5 +/- 0.3 (stat) +/. 3.1 (syst) 0.8 (lumi) ub. The differential cross sections for pi+pi- pairs as a function of the pion pair invariant mass, pT, and y, as well as a single-pion differential cross section as a function of pion pT are also measured and compared to several phenomenological predictions.

Relatore: Mohsen Khakzad (IPM)

Slides Mohsen_Khakzad_DIffraction2016_Sept2_Italy_v3.pdf

12:30 Central Exclusive K+K- production in CDF

We present new CDF data on exclusive K+ K- and p-pbar production. Data were taken at sqrt(s) = 1960 GeV and 900 GeV in low pile-up conditions. Events were selected with exactly two well-measured central tracks with PT > 300 MeV/c and |eta| < 0.8 and no evidence for other particles (including calorimeter clusters) in the range -5.3 < eta < +5.3, signifying two rapidity gaps exceeding Delta-eta = 4.5. These events should be dominated by double pomeron exchange, with a central state having IG JPC = 0+ (even)++. Kaons and (anti-)protons were identified using a barrel of time-of-flight scintillation counters.

Relatore: Antonio Gioiosa (LE)

Slides Diff2016_gioiosa_def.pdf

12:50 Recent results on Central Exclusive Production with the STAR detector at RHIC

The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) performs studies of diffractive processes with the focus on the exclusive production of particles in central range of rapidity. In 2015 STAR collected 18~pb$^{-1}$ of data in polarized proton+proton collisions at $\sqrt{s}$~=200~GeV to measure Central Exclusive Production process $pp\to pXp$ (CEP) through Double Pomeron Exchange (DPE) mechanism, which is expected to be dominant at this center-of-mass energy. The intact protons moving inside the RHIC beampipe after the collision were measured in silicon strip detectors, which were placed in the Roman Pot vessels. This enables full control over interaction kinematics and clear verification of the exclusivity of the reaction by measuring the total (missing) transverse momentum of all final state particles: the central diffractive system in the Time Projection Chamber (TPC) and the forward protons in the Roman Pots. With the use of ionization energy loss in the TPC, d$E$/d$x$, as well as velocity measured with TPC and barrel Time-Of-Flight detector (TOF) it was possible to discriminate various production channels in $pp\to pXp$ reaction. We shall present preliminary results on exclusive production of two ($\pi^{+}\pi^{-}$, $K^{+}K^{-}$, $p\bar{p}$) and four ($\pi^{+}\pi^{-}\pi^{+}\pi^{-}$) charged particles in mid-rapidity region, $|\eta|<1$, with small squared four-momentum transfer of forward protons, $0.03<|t_{1}|,|t_{2}|<0.3~(\textrm{GeV}/c)^{2}$.

Relatore: Rafal Sikora (AGH University of Science and Technology)

Slides Diffraction2016_RafalSikora.pdf

13:10 Status of the AFP project in ATLAS

Detector description and experience with first data will be reported.

Relatore: Marek Tasevsky (ATLAS)

Slides Tasevsky-Diffraction2016-AFP.pdf Tasevsky-Diffraction2016-AFP.ppt

13:30 → 16:00 Lunch and leisure time

16:00 → 17:40 Diffraction in hadron-hadron collisions - phenomenology/theory (I)

Coordinatore: Prof. Boris Kopeliovich (UTFSM)

16:00 Precision RENORM Tensor-Pomeron Cross Sections at LHC and Beyond

Precision predictions of soft and hard diffraction, elastic scattering, and total proton-proton cross sections, based on a tensor-Pomeron implementation of the RENORM model, are compared to the latest experimental results at the LHC and cosmic-ray experiments, and extended to the planned SuperCollider energies.

Relatore: Konstantin Goulianos (The Rockefeller University)

Slides D2016DinoTalk.ppt

16:25 Exclusive diffractive production of pion pairs and resonances in proton-proton collisions within tensor pomeron approach.

We present estimates of the cross sections and differential distributions for central exclusive two and four pions production being studied at RHIC and LHC. The amplitudes for the processes are formulated in terms of the double tensor pomeron and $f_{2 \Reg}$ reggeon exchanges with the vertices respecting the standard crossing and charge-conjugation relations of Quantum Field Theory. In the reaction $pp \to pp \pi^{+} \pi^{-}$ we include the dipion continuum, the dominant scalar and tensor resonances decaying into $\pi^{+} \pi^{-}$ pairs as well as the contribution from photoproduction ($\rho(770)$ and Drell-S\"oding terms). The theoretical results are compared with the existing STAR, CDF, CMS experimental data and predictions for planned or current experiments (ATLAS, ALICE) are presented. We find that the relative contribution of resonant $f_2(1270)$ and dipion continuum strongly depends on the cut on four-momentum transfer squared $t_{1,2}$ which may explain some controversial observations made by different ISR experiments in the past. We suggest some experimental analyses to fix model parameters related to the pomeron-pomeron-meson coupling. We present first predictions of the $\sigma \sigma$ and $\rho \rho$ contributions to the $pp \to pp \pi^{+} \pi^{-} \pi^{+} \pi^{-}$ reaction. We compare the four-pion results of our calculation with the ISR experimental data. We show the influence of the experimental cuts on the integrated cross section and on various differential distributions for outgoing particles. The cuts may play then the role of a $\pi \pi$ resonance filter. 1. C. Ewerz, M. Maniatis, and O. Nachtmann, A Model for Soft High-Energy Scattering: Tensor Pomeron and Vector Odderon, Annals Phys. 342 (2014) 31. 2. P. Lebiedowicz, O. Nachtmann, and A. Szczurek, Exclusive central diffractive production of scalar and pseudoscalar mesons; tensorial vs. vectorial pomeron, Annals Phys. 344 (2014) 301. 3. P. Lebiedowicz, O. Nachtmann, and A. Szczurek, $\rho^{0}$ and Drell-S\"oding contributions to central exclusive production of $\pi^{+}\pi^{-}$ pairs in proton-proton collisions at high energies, Phys. Rev. D91 (2015) 074023. 4. P. Lebiedowicz, O. Nachtmann, and A. Szczurek, Central exclusive diffractive production of the $\pi^{+}\pi^{-}$ continuum, scalar and tensor resonances in $pp$ and $p\bar{p}$ scattering within the tensor Pomeron approach, Phys. Rev. D93 (2016) 5, 054015. 5. P. Lebiedowicz, O. Nachtmann, and A. Szczurek, Exclusive diffractive production of $\pi^{+}\pi^{-}\pi^{+}\pi^{-}$ via the intermediate $\sigma \sigma$ and $\rho \rho$ states in proton-proton collisions within tensor Pomeron approach, in print in Phys. Rev. D.

Relatore: Piotr Lebiedowicz (Institute of Nuclear Physics Polish Academy of Sciences, Kraków)

Slides Lebiedowicz.pdf

16:50 Exclusive J/psi process tamed to probe the low x gluon

The perturbative QCD expansion for J/psi photoproduction appears to be unstable: the NLO contribution is large (and of opposite sign) to the LO contribution. Moreover, the predictions are very sensitive to the choice of factorization and renormalization scales. Here we show that perturbative stability is achieved by imposing a `Q_0 cut' on the NLO coefficient functions; a cut which is required to avoid double counting. Q_0 is the input scale used in the parton DGLAP evolution. This result opens the possibility of high precision exclusive J/psi data in the forward direction at the LHC (that is, pp -> p + J/psi + p data) being able to determine the low x gluon distribution at low scales.

Relatore: Alan Martin (IPPP, Durham University)

Slides Martin.pdf Martin.pptx

17:15 Correlations in forward diffractive Abelian and non-Abelian radiation

I present a brief overview of recent advances in single diffractive Drell-Yan, heavy flavour and Higgs boson production at forward rapidities in the dipole picture. Physical reasons for diffractive factorisation breaking in single diffractive production are discussed in detail. Angular correlation in forward diffractive heavy flavor and Drell-Yan production processes is considered as a natural probe for saturation phenomena.

Relatore: Roman Pasechnik (Lund University)

Slides Acireale-diff.pdf

17:40 → 18:10 Coffee break

18:10 → 19:25 Diffraction in hadron-hadron collisions - phenomenology/theory (II)

Coordinatore: Prof. Boris Kopeliovich (UTFSM)

18:10 Low missing mass single- and double diffraction dissociation at the LHC

Low missing mass (resonance region) single- and double proton diffraction dissociation is studied with emphasis on the LHC data. Regge-pole factorization, duality relations and unitarity bounds are discussed.

Relatore: Laszlo Jenkovszky (Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine)

Slides Jenkovszky.pptx

18:35 The dispersion relations and analysis of the new LHC data

Analysis of the new experimental data obtained by the TOTEM and ATLAS Collaborations at LHC at \sqrt{s} = 7 and 8 TeV at small momentum transfer is presented. Some contradictions in the obtained sizes of the total cross sections are analyzed. The impact of the different assumptions on the extraction of the parameters of the elastic scattering amplitude, especially on the size of the total cross sections, is examined. The determination of the phase of the elastic scattering amplitude from the point of view of the Dispersion Relation is carried out. The origins of the dependence of the slopes of the different parts of the scattering amplitude over the momentum transfer are analyzed with taken into account the different models assumptions. Our new method of extracting the real part of the hadron scattering amplitude from experimental data is used to obtain the the size of \sigma_tot(s) and \rho(s; t) and compare with the the parameters of the the hadron scattering amplitude obtained by the TOTEM and ATLAS Collaborations. The analysis of the data is compared with the similar analysis in the Regge approach for the hadron scattering amplitude.

Relatore: Oleg Selyugin (JINR)

Slides Selyugin.pdf Selyugin.pptx

19:00 Diffractive production of J/psi in pp collisions with proton dissociation

The amplitude for $\gamma p \to V p$, where $V$ is a $J/\psi$ or $\Upsilon$ ground state or excited vector meson, is calculated in a pQCD $k_{T}$-factorization approach. We use this amplitude to predict the cross section for exclusive photoproduction of $J/\psi, \psi'$ mesons in proton-proton collisions. Calculations are performed for a variety of unintegrated gluon distributions, and we compare our results to LHCb data. Here we especially focus on diffractive production in proton dissociative events. We notice, that electromagnetic dissociation is calculable directly from proton structure functions without additional free parameters. Besides being of interest in their own right, dissociative events constitute an important experimental background to exclusive production.

Relatore: Wolfgang Schaefer (Institute of Nuclear Physics PAN)

Slides WS_DIffraction_16.pdf

20:30 → 23:30 Social dinner

mercoledì 7 settembre

09:20 → 11:00 Progress in QCD (III)

Coordinatore: Dr. Joachim Bartels (University Hamburg)

09:20 Inclusive three- and four-jet production in multi-Regge kinematics at the LHC

In this talk a study of differential cross sections for the production of three and four jets in multi-Regge kinematics is presented. The main focus lies on the azimuthal angle dependences in events with two forward/backward jets tagged in the final state. Furthermore, the tagging of one or two extra jets in more central regions of the detector with a relative separation in rapidity from each other is requested. It is found that the dependence of the cross sections on the transverse momenta and the rapidities of the two central jets can offer new means of studying the onset of BFKL dynamics.

Relatore: Francesco Giovanni Celiberto (CS)

Slides talk_Diffraction_2016_multi-jet_Celiberto.pdf

09:40 Computation of NLO processes involving heavy quarks using Loop-Tree Duality

We present a new method to compute higher-order corrections to physical cross-sections, at Next-to-Leading Order and beyond. This method, based on the Loop Tree Duality, leads to locally integrable expressions in four dimensions. By introducing a physically motivated momentum mapping between the momenta involved in the real and the virtual contributions, infrared singularities naturally disappear at integrand level, without the need to introduce subtraction counter-terms. Ultraviolet singularities are dealt with using dual representations of suitable counter-terms, with some subtleties regarding the self-energy contributions. We first apply this method to a $1\to2$ scalar process, and then compute the decay rate for $H\to q\overline{q}$, $\gamma\to q\overline{q}$ and $Z\to q\overline{q}$.

Relatore: Felix Driencourt-Mangin (IFIC)

Slides LTDDiff2016.pdf

10:00 What can we learn from dilepton angular distributions at Z0 peak at the LHC?

Recently ATLAS published new data on dilepton angular coefficients in Z-boson production at the energy 8 TeV. In particular the famous Lam-Tung relation was shown to be broken and NNLO QCD corrections could explain only a fraction of this phenomenon. We investigate properties of the dilepton angular distributions and Lam-Tung relation breaking within kT-factorization framework and confront predictions of several models with ATLAS data.

Relatore: Tomasz Stebel (Jagiellonian University)

Slides Sicily_Stebel.pdf Sicily_Stebel.pptx

10:20 Estimating the branching fraction for $B^0\rightarrow \psi(2S)\pi^0$ decay

I present estimates of the branching fractions in the non-leptonic charmonium two-body decay rates for $B^0\rightarrow \psi(2S)\pi^0$ decay and the same decays of $B^+\rightarrow \psi(2S)\pi^+$, $B^0\rightarrow \psi(2S)K^0$ and $B^+\rightarrow \psi(2S)K^+$. These estimates are based on a generalized factorization approach making use of leading order (LO) and next-to-leading order (NLO) contributions. I find that when the large enhancements from the known NLO contributions by using the QCD factorization approach are taken into account, the branching ratios are the following: $Br(B^0\rightarrow \psi(2S)\pi^0)=(1.067\pm0.059)\times10^{-5}$, $Br(B^+\rightarrow \psi(2S)\pi^+)=(2.134\pm0.0.118)\times10^{-5}$, $Br(B^0\rightarrow \psi(2S)K^0)=(6.344\pm0.376)\times10^{-4}$ and $Br(B^+\rightarrow \psi(2S)K^+)=(6.344\pm0.376)\times10^{-4}$, while the experimental results are $(1.17\pm 0.17)\times 10^{-5}$, $(2.44\pm 0.30)\times 10^{-5}$, $(6.20\pm 0.50)\times 10^{-4}$ and $(6.39\pm 0.33)\times 10^{-4}$ respectively. All estimates are in good agreement with the experimental results.

Relatore: Behnam Mohammadi (Urmia University)

Slides Diffraction_2016.pptx

10:40 Small-x resummation for DVCS, TCS and exclusive vector meson production

Some hard exclusive processes can be described in a framework of QCD collinear factorization. The amplitudes of Deeply Virtual Compton Scattering (DVCS), its crossing counterpart Timelike Compton Scattering (TCS) and the amplitudes of neutral light and heavy vector meson (VM) production can be calculated as a convolution of hard coefficient functions and generalized parton distributions. It is known that the first perturbative corrections to the processes of VM production are very large in diffractive region of small x, which calls for the resummation of enhanced contributions at higher orders. We showed that based on BFKL resummation approach applied earlier to small x DIS may be generalized to these hard exclusive reactions. We obtain analytical results for resummed coefficient functions of DVCS, TCS and VM production processes. Our analysis shows that the account of the high energy resummation stabilizes predictions for heavy VM photoproduction.

Relatore: Dmitry Ivanov (Sobolev Institute of Mathematics)

Slides Ivanov.pdf

11:00 → 11:30 Coffee break

11:30 → 13:20 Diffraction in hadron-hadron collisions - experiment (IV)

Coordinatore: Christina Mesropian (Rockefeller University)

11:30 CT-PPS: the program and it's possible development

The CMS-TOTEM Precision Proton Spectrometer (CT-PPS) has the goal of studying central exclusive production processes in proton-proton collisions at LHC. Such processes are characterized by the presence of two protons scattered at small angles and detected inside the LHC beam pipe with CT-PPS, along with one or more particles produced at small rapidity values and detected by the central CMS detector. This gives access to a variety of interesting subjects, including the study of quartic gauge couplings and searches for new resonances produced in photon-photon or gluon-gluon fusion. A description of the experimental set-up will be presented, along with the current status of the project.

Relatore: Fabrizio Ferro (GE)

Slides CTPPS-at-Diffraction2016.pdf

11:50 AD, the ALICE at LHC Diffractive detector

Abraham Villatoro Tello*, for the ALICE Collaboration. *FCFM, Benemérita Universidad Autónoma de Puebla. ALICE is one of the four large experiments at the CERN Large Hadron Collider (LHC). As a complement to the Heavy-Ion physics program, ALICE started during Run 1 of LHC an extensive program dedicated to the study of proton-proton diffractive processes. In order to optimize its trigger efficiencies and purities in selecting the diffractive events, the ALICE Collaboration installed a very forward AD detector during the Long Shut Down 1 of LHC. The new forward detector system consists of two stations made of two layers of scintillator pads, one station on each side of the interaction point. With this upgrade, ALICE has substantially increased its forward physics coverage, including the double rapidity gap based selection of central production, as well as the measurements of inclusive diffractive cross sections. In this talk, a review of the performance of AD detector will be given.

Relatore: Abraham Villatoro Tello (Benemérita Universidad Autónoma de Puebla)

Slides Abraham_VT_Diffraction_2016.pdf Abraham_VT_Diffraction_2016.pptx

12:10 Upgrades for the CT-PPS detector

I would present the upgrades foreseen for the CMS-Totem Precision Proton Spectrometer experiment, including -among others- upgrades for the tracking and timing detectors, and the time-reference system.

Relatore: Michele Gallinaro (LIP Lisbon)

Slides Gallinaro.pdf

12:30 Turning the LHC Ring into a New Physics Search Machine

The LHC Collider Ring is proposed to be turned into an ultimate automatic search engine for new physics in three consecutive phases: (1) Searches for heavy particles produced in Central Exclusive Process (CEP): pp → p + X + p based on the existing Beam Loss Monitoring (BLM) system of the LHC; (2) Extensions to the current BLM system to facilitate precise registration of the selected CEP proton exit points from the LHC beam vacuum chamber; (3) Integration of the BLM based event tagging system together with the trigger/data acquisition systems of the LHC experiments to facilitate an on-line automatic search machine for the physics of tomorrow.

Relatore: Risto Orava (Helsinki Inst. of Physics and Univ. of Helsinki, CERN)

Slides diffraction_2016_v1_(1).pptx

12:50 Searching for New Physics with Dedicated Experiments@ the LHC

We discuss a number of recent ideas for dedicated experiments at the LHC for the search of new physics, which are complementary to the large general purpose experiments ATLAS and CMS. These dedicated experiments aim to search for either monopoles, particles with millicharges or long lived particles with decay lengths of 100s of meters.

Relatore: Albert De Roeck (CERN)

Slides Deroeck.pptx

13:20 → 16:00 Lunch and leisure time

16:00 → 17:35 Diffraction in nuclear collisions (I)

Coordinatore: Dr. Leszek Adamczyk (AGH University of Science and Tecnology)

16:00 Ultra-peripheral collisions with the ATLAS detector

The large equivalent-photon fluxes accompanying Pb ion beams at the LHC initiate photon-photon and photo-nuclear interactions which dominate when the colliding nuclei have large impact parameter (ultra-peripheral collisions). These electromagnetically-induced processes are sensitive to the nuclear wave-function and in particular the nuclear modifications of the nucleon parton distribution functions (nPDFs).  As such, they are complementary to the ongoing p+A program at RHIC and the LHC, as well as the upcoming electron-ion collider in the US. The absolute rates of single and multiple neutron emission into one or both ZDCs will be presented, to test theoretical predictions for the photon flux as well as nuclear absorption. High-mass dilepton pair continuum rates will also be studied to test expectations for two-photon interactions.

Relatore: Miguel Arratia (ATLAS)

Slides UPCTalk_Diffraction16.pdf

16:25 ALICE results on vector meson photonuclear production in Pb-Pb collisions

The strong electromagnetic fields generated by ultra-relativistic heavy ions offer the possibility to study photoproduction processes at the LHC. In so called ultra-peripheral collisions (UPC), when the impact parameter of the incoming hadrons is larger than the sum of their radii, hadronic processes are strongly suppressed and only electromagenetic interactions remain. ALICE has measured the coherent photo-nuclear production of $\rho^0$, J/$\psi$ and $\psi(2S)$ vector mesons in ultra-peripheral collisions of lead nuclei. These processes provide information on the gluon structure of the nuclear target at low Bjorken-$x$. The talk will cover the results from LHC Run1 data, as well as discuss the current status and prospects for analyses with LHC Run2 data.

Relatore: Guillermo Contreras (FJFI CVUT Prague)

Slides Diff2016_v3.pdf

16:50 Photoproduction of J/psi and electron-positron pairs in ultra-peripheral p-Pb and Pb-Pb collisions with the ALICE detector

Ultra-relativistic heavy ions generate strong electromagnetic fields, which offer the possibility to study photon-photon, photon-nucleus and photon-proton processes at the LHC in ultra-peripheral p-Pb and Pb-Pb collisions (UPC). Exclusive photoproduction of vector mesons is sensitive to the gluon distribution of the interacting target (proton or nucleus) whereas exclusive production of lepton pairs in the photon-photon interactions in Pb-Pb probes quantum electrodynamics with a large coupling constant. Here we present ALICE measurements of J/psi vector meson photoproduction in p-Pb UPC at sqrt(s_NN) = 5.02 TeV. We report the results in several intervals of the photon-proton center-of-mass energy which is constrained by the the rapidity of the vector meson. Furthermore, we present results on exclusive electron-positron pair production in photon-photon collisions in Pb-Pb UPC at sqrt(s_NN) = 2.76 TeV.

Relatore: Jaroslav Adam (Czech Technical University in Prague, Creighton University, Omaha)

Slides JA-UPC_Diffraction2016.pdf

17:10 Results (and future prospects) of the CMS experiment in photon-induced collisions in p-Pb collisions

Exclusive vector meson (Upsilon and Rho0) photoproduction is studied in ultra-peripheral pPb collisions at √sNN =5.02 TeV with the CMS experiment at the LHC. The cross sections are measured as a function of the photon-proton centre-of-mass energy, extending the energy range explored by H1 and ZEUS Experiments at HERA. In addition, the differential cross sections (dσ/d|t|), where|t|≈ p^2_T is the squared transverse momentum of produced vector mesons, are measured and the slope parameters are obtained. The results are compared to previous measurements and to theoretical predictions. Finally, prospect for further measurements of vector meson production that can be performed using the 2016 pPb collision data at 8 TeV to be collected at the end of the year are presented.

Relatore: Alexander Bylinkin (Moscow Instittue of Physics and Technology)

Slides Bylinkin_Diffraction_2016.pdf

17:35 → 18:05 Coffee break

18:05 → 19:20 Diffraction in nuclear collisions (II)

Coordinatore: Prof. Alan Martin (IPPP, Durham University)

18:05 Ultra Peripheral Collisions in the HI collisions at LHC

not available

Relatore: Daniel Tapia Takaki (IPN Orsay, Paris-sud)

Slides DTT-UPC_Diffraction_2016_.pdf

18:30 Recent results from the STAR experiment on Vector Meson (VM) production in ultra peripheral AuAu collisions at RHIC.

In this talk we shall present the measurements involving photonuclear production of vector meson (rho, omega, J/psi) and non-resonant pion pair in AuAu ultra peripheral collisions (UPC) at RHIC. Measurements of the relative amplitudes of the light vector mesons and direct pion pair components will be presented, along with the phase angle between the rho and omega components. The negative of the four momentum transfer squered (t) spectrum shows coherent and incoherent components. The coherent component exhibits visible diffraction minima. Preliminary results for the cross section as a function J/psi rapidity and transverse momentum will be presented and compared to models. Plans for the future will also be discussed.

Relatore: Leszek Adamczyk (AGH University of Science and Tecnology)

Slides diffraction_adamczyk.pdf

18:55 New results for ultraperipheral heavy ion collisions

We shall discuss two reactions: $A A \to A A \gamma \gamma$ and $A A \to A A e^+ e^- e^+ e^-$. In the first case we shall discuss connections with elastic $\gamma \gamma$ scattering. Several mechanisms are included: lepton and quark boxes, vector-dominance mechanism and two-gluon exchange mechanism. The calculations are done in the equivalent photon approximation in the impact parameter space (EPA-b). Several differential distributions are calculated. Feasibility studies will be presented. Measurable counting rates are obtained. A special attention is devoted to searches for hints of the VDM-Regge mechanism as well as two-gluon exchange one. The studies show that first identification/measurement of elastic $\gamma \gamma$ scattering is accessible with present experimental infrastructure. The expected number of events will be given. In the second case of four-lepton production we consider only double scattering $\gamma \gamma \to e^+ e^-$ mechanism. As in the first case the calculation are done in the EPA-b. We present several differential distributions imposing experimental cuts on rapidities and transverse momenta relevant for different experiments at the LHC. Corresponding number of counts will be given. Our study show that corresponding measurements should be possible soon and would allow a first identification of the double scattering mechanism.

Relatore: Antoni Szczurek (Institute of Nuclear Physics, Krakow and Rzeszow University, Rzeszow)

Slides Szczurek.pdf

19:20 → 19:30 Closing address

19:20 Closing address

Relatore: Alessandro Papa (CS)

Slides Closing.pptx

20:30 → 22:00 Dinner