Francesco Fidecaro
(Pisa University),
Marco Grassi
(INFN-Pisa)
29/06/2015, 09:10
Talk
Heinrich Leutwyler
(University of Bern)
29/06/2015, 09:25
Talk
Many of the quantities of interest at the precision frontier in particle physics require a good understanding of the low energy properties of the strong interaction. I intend to focus on the fact that applications of effective field theory methods usually involve two aspects: dependence on the quark masses and dependence on the momenta. On the one hand, I will review some of the work done in...
Claude Bernard
(Washington University, Saint Louis)
29/06/2015, 10:05
Talk
I describe some of the many connections between lattice QCD and effective field theories, focusing in particular on chiral effective theory, but also touching upon Symanzik effective theory and heavy quark effective theory. Ifirst discuss the ways in which effective theories have enabled and supported lattice QCD calculations. Particular attention is paid to the inclusion of discretization...
David Hornidge
(Mount Allison University)
29/06/2015, 11:10
Talk
Recent measurements and future plans for photopion experiments with the CB-TAPS detector system in the A2 hall at the Mainzer Microtron will be presented. First, a measurement with linearly polarized photons and an unpolarized liquid-hydrogen target will be discussed. The beam asymmetry along with differential cross sections provide the most stringent test to date of the predictions of Chiral...
Vincenzo Cirigliano
(Los Alamos National Laboratory)
29/06/2015, 11:50
Talk
Electric Dipole Moments (EDMs) of leptons, nucleons, atoms, and molecules are great probes of new sources of CP violation originating from physics beyond the Standard Model (BSM). In this talk I will discuss the central role that QCD and chiral dynamics play in the interpretation of current experimental searches. After an overview of the physics reach of various EDM searches, I will...
Liping Gan
(University of North Carolina, Wilmington)
29/06/2015, 12:30
Talk
Light Meson decays provide a unique laboratory to probe fundamental QCD symmetries and to search for new physics beyond the Standard Model. A comprehensive Primakoff experimental program at Jefferson Laboratory (Jlab) is aimed at gathering high precision measurements on the two-photon decay widths and transition form factors at low Q2 of π0, η and η′ via the Primakoff effect. Completed...
Nicolas Garron
(Plymouth University)
29/06/2015, 14:30
CP violation was discovered in Kaon decays 50 years ago but still remains a challenge for theorists. A complete theoretical description will be a crucial test for the Standard Model and will provide us with a rich source of information on new physics theories. In the past recent years, realistic computations of A2, the amplitude of K->(pipi)_(I=2), have become possible and reached a level of...
Martin Savage
(Institute for Nuclear Theory, Seattle)
29/06/2015, 14:30
I will present the recent results of lattice QCD calculations of the interactions of nucleons and light nuclei with magnetic fields. Their magnetic moments and polarizabilities have been calculated at pion masses of 805 MeV and 450 MeV. Interestingly, the magnetic moments, when given in terms of natural nuclear magnetons, are found to be consistent with the experimental values. I also present...
Carl Carlson
(College of William and Mary, Williamsburg)
29/06/2015, 14:30
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
The proton charge radius puzzle exists because the proton charge radius appears different when measured with electrons than when measured with muons. "Ordinary" explanations include problems with the extrapolations or theoretical corrections involved in the measurements, and "exotic" explanations include such beyond the standard model ideas as a breakdown of electron-muon universality. We...
David Wilson
(Old Dominion University, Norfolk)
29/06/2015, 14:55
Recently it has become possible to obtain coupled-channel scattering amplitudes using lattice QCD. Using a large basis of operators we are able to obtain a reliable finite volume spectrum describing the coupled pi-K, eta-K system. Utilizing the finite volume formalism proposed by Luescher and extended by several others, we are able to describe the spectra from each lattice symmetry group and...
Ricardo Alarcon
(Arizona State University, Tempe)
29/06/2015, 15:00
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
The OLYMPUS experiment will determine the multiple-photon exchange contribution to elastic lepton-proton scattering, the most likely candidate to resolve the discrepancy between measurements of the proton electric to magnetic form factor ratio, determined using the Rosenbluth separation technique and polarization transfer methods. To this end, the experiment measured the cross section ratio of...
Jacopo Pinzino
(INFN-Pisa)
29/06/2015, 15:00
We report the first observation of the very rare decay K+- -> pi+- pi0 e+ e- by the NA48/2 experiment. From a clean sample of almost 2000 reconstructed signal events, we have determined the branching fraction with high precision and measured the e+ e- invariant mass distribution, which allows to differentiate between different decay models.
Lorenzo Contessi
(TIFP, Trento)
29/06/2015, 15:10
In the last years Lattice QCD has substantially improved its predictive power for light nuclei [1,2,3]. Now we have access to data for light nuclei in systems with high pionic mass. We argue that the proper low-energy theory is a contact (or pionless) approach, since for these systems pion effects are of short-range. By means of this effective theory it is possible to extend LQCD predictions...
Franziska Hagelstein
(Johannes Gutenberg University, Mainz)
29/06/2015, 15:20
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
We present the predictions of baryon chiral perturbation theory (BChPT) for the proton polarizability contribution to the 2P −2S Lamb shift and the 2S hyperfine splitting (HFS) in muonic hydrogen, and compare them to the results of dispersive calculations. The spin-dependent part of the forward doubly-virtual Compton scattering amplitude (S1,2) contributes to the 2S HFS, whereas the...
Michal Zamkovsky
(IPNP, Charles University, Prague)
29/06/2015, 15:20
The NA48/2 experiment has recently published a detailed study of the Ke4 decay mode K —> pi0 pi0 e nu based on 65000 candidates with a low 1% background contamination. The achieved experimental precision brings evidence for isospin breaking mass effects and final state pi pi scattering. Theoretical calculations will have to face a new precision challenge when using such improved inputs to...
Vadim Baru
(Ruhr University, Bochum)
29/06/2015, 15:25
The low-energy theorems (LET) for NN scattering are known to provide important relations between the coefficients in the effective-range expansion (ERE) of the amplitude, which are governed by the long-range part of the potential, see, e.g., [1, 2]. Therefore, as long as the long-range physics is appropriately included in the calculation, these relations should yield model independent...
Vladimir Pascalutsa
(Johannes Gutenberg University, Mainz)
29/06/2015, 15:40
The present treatment of the nucleon-nucleon and few-nucleon forces in chiral effective theory is semi-relativistic. One of the immediate difficulties of this description is that, in accordance with Wigner’s causality bound, the leading-order (zero-range) interaction yields zero effective range. This leads to the necessity of “promoting” the subleading three-body force to leading order, in the...
Marc Knecht
(CNRS/CPT, Marseille)
29/06/2015, 15:40
The very precise data obtained by the NA48/2 collaboration at the CERN SPS on the decay channels K^\pm \to \pi^+ \pi^- e^\pm \stackrel{_{(-)}}{\nu_e}$ and $K^\pm \to \pi^0 \pi^0 e^\pm \stackrel{_{(-)}}{\nu_e}$ have made it necessary to address issues related to isospin breaking. Three aspects related to this issue will be considered: isospin breaking due to the pion mass difference in the...
Nadiia Krupina
(Johannes Gutenberg University, Mainz)
29/06/2015, 15:40
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
We consider the predictions of Chiral Perturbation Theory (ChPT) for the third Zemach moment and Zemach radius and confront them with empirical values. We look at implications of these results for the Lamb shift and hyperfine structure of (muonic) hydrogen.
Harald W. Griesshammer
(George Washington University, Washington)
29/06/2015, 16:20
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
Compton scattering from protons and neutrons probes the two-photon response of the nucleon in electric and magnetic fields at fixed photon frequency and multipolarity [1]. It provides detailed tests of the symmetries and strengths of the interactions of the nucleonic constituents with each other and with photons. Proton-neutron differences explore the interplay between chiral symmetry breaking...
Matthias Schindler
(University of South Carolina, Columbia)
29/06/2015, 16:20
Parity-violating interactions between nucleons are the manifestation of an interplay of strong and weak interactions between quarks in the nucleons. Because of the short range of the weak interactions, these parity-violating forces provide a unique probe of low-energy strong interactions. An ongoing experimental program is mapping out this weak component of the nuclear force in few-nucleon...
Peter Stoffer
(HISKP, University of Bonn)
29/06/2015, 16:20
K_{l4} decays have several features of interest: they allow an accurate measurement of ππ-scattering lengths; the decay is the best source for the determination of some low-energy constants of chiral perturbation theory (χPT); one form factor of the decay is connected to the chiral anomaly. We present the final results of our dispersive analysis of K_{l4} decays, which provides a resummation...
Xian-Wei Kang
(IAS and IKP, Forschungszentrum Jülich)
29/06/2015, 16:40
The Cabibbo-Kobayashi-Maskawa matrix element |Vub| is not well determined yet. It can be extracted from both inclusive or exclusive decays, like B → ρ(π)l¯νl. However, the exclusive determination from B → ρl¯νl, in particular, suffers from a large model dependence. In this talk, I will elaborate our proposal [1]: extracting |Vub| from the four- body semileptonic decay B → ππl¯νl, where the...
Michael Gericke
(University of Manitoba, Winnipeg)
29/06/2015, 16:45
The n3He experiment aims to measure the parity violating asymmetry in the direction of proton emission in the reaction vec{n}+3He-> 3H+p, using the capture of polarized cold neutrons in an unpolarized gaseous 3He target. Using effective field theory based calculations, the size of the asymmetry is estimated to be in the range of (-9.5 --> 2.5) X 10^{-8}, and our goal measurement accuracy is 2...
Gerald Feldman
(George Washington University, Washington)
29/06/2015, 16:50
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
The electric and magnetic polarizabilities of the proton are now relatively well known, owing to Compton scattering measurements on hydrogen targets over the past 20 years [1]. However, in the case of the neutron, these structure constants are still quite uncertain, due to the fact that there are no free neutron targets and that quasi-free Compton scattering on a neutron in a nucleus has a...
Balasubramanian Ananthanarayan
(Indian Institute of Science, Bengaluru)
29/06/2015, 17:00
Motivated by the discrepancies noted recently between the theoretical calculations of the electromagnetic ωπ form factor and certain experimental data, we investigate this form factor using analyticity and unitarity in a framework known as the method of unitarity bounds. We use a QCD correlator computed on the spacelike axis by operator product expansion and perturbative QCD as input, and...
Alessandro Baroni
(Old Dominion University, Norfolk)
29/06/2015, 17:00
We present the derivation of two-nucleon axial charge and current operators in chiral effective field theory up to order Q in the power counting, where Q denotes generically the low momentum scale. The derivation is based on time-ordered perturbation theory, and accounts for cancellations between the contributions of irreducible diagrams and those due to non-static corrections from energy...
Jose Manuel Alarcon
(University of Bonn)
29/06/2015, 17:10
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
The electromagnetic structure of the nucleon has an increasing interest for experimental searches of physics beyond the standard model in the precision frontier. The reason is that, due to the remarkable accuracy of the experimental measurements, it is crucial to have a good understanding over all possible contributions. The polarizabilities give the information about the two photon exchange...
Alejandro Kievsky
(INFN-Pisa)
29/06/2015, 17:15
Efimov physics has been intensively studied in the L=0, spatially symmetric state of the three-boson system. In the case of three nucleons, the three and four-body systems have a large symmetric component allowing the study of Efimov physics. To be recalled in this context the large values of the singlet and triplet two-nucleon scattering lengths. In this presentation we will show results for...
Tadeusz Janowski
(University of Southampton)
29/06/2015, 17:20
We present the recent lattice QCD calculation of K-π I=3/2 and I=1/2 scattering lengths by the RBC-UKQCD collaboration. Our calculation is the first lattice calculation of these quantities performed using physical point ensembles [1]. This allows us to bypass the error due to chiral extrapolation, which in current calculations is the dominant source of systematic errors [2,3,4,5]. Preliminary...
Astrid Hiller Blin
(IFIC, University of Valencia)
29/06/2015, 17:30
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
We investigate the neutral pion photoproduction on the proton near threshold in covariant chiral perturbation theory with the explicit inclusion of Delta degrees of freedom. This channel is specially sensitive to chiral dynamics and the advent of very precise data from the Mainz microtron has shown the limits of the convergence of the chiral series for both the heavy baryon and the covariant...
Tobias Frederico
(Instituto Tecnologico de Aeronautica, Sao Jose dos Campos)
29/06/2015, 17:30
The universal properties of weakly bound tetramers close to the unitary limit are obtained by solving Faddeev-Yakubovsky (FY) equations for identical bosons with a zero-range interaction. The solution of these equations demand beside a short-range three-body scale another one for the four-boson system. We explore the correlation between trimer and tetramer energies are shown to be...
Thomas Rössler
(Lund University)
29/06/2015, 17:40
The talk will cover the recent progress in Chiral Perturbation Theory at two-loop order in finite volume. The techniques used in the two-loop finite volume integrals [1] will be described shortly and afterwards applications to masses and decay constants both for the standard case in two and three flavours [2] and partially quenched for three sea quark flavours [3] will be discussed.
[1]...
Arseniy Filin
(Ruhr University, Bochum)
29/06/2015, 17:45
Study of pion production near threshold is interesting for several reasons: it tests applicability of chiral EFT at intermediate energies, probes nucleon-nucleon dynamics at relatively large transferred momenta, and gives possibility to study isospin violation in few-body processes. The neutral pion production in pp → ppπ0 channel has been known to be the most puzzling process for a long time....
Lloyd Cawthorne
(University of Manchester)
29/06/2015, 17:50
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
In this talk we will discuss the reaction p + γ → p + π0 and how it has been described using Chiral Perturbation Theory (χPT).
Since the early 1990s χPT has been applied to pion photoproduction. The first study was that of Bernard et al. [1,2], detailing a O(p3) relativistic approach to describe the data from Mainz [3] and Saclay [4] from threshold, Eγ ≈ 145 MeV, to Eγ ≈ 160 MeV. In 1996...
Johan Relefors
(Lund University)
29/06/2015, 18:00
The talk will describe the recent work at one-loop Chiral perturbation Theory with twisted boundary conditions [1]. We point out that due to the broken Lorentz and reflection symmetry a number of new terms show up in the expressions. The pseudo-scalar octet masses, axial-vector and pseudo-scalar decay constants and electromagnetic form-factors will be discussed explicitly. We show how the...
Maxim Mai
(HISKP, University of Bonn)
29/06/2015, 18:00
The recoil retardation effect in the K¯d scattering length is studied. Using the nonrelativistic effective field theory approach, it is demonstrated that a systematic perturbative expansion of the recoil corrections in the parameter ξ=MK/mN is possible in spite of the fact that K-d scattering at low energies is inherently nonperturbative due to the large values of the K¯N scattering lengths....
Takashi Inoue
(Nihon University)
30/06/2015, 08:45
Talk
Explaining and predicting properties of nuclei starting from QCD is one of the most challenging problems in physics. There are several attempts to extract mass of nuclei in lattice QCD simulations, but direct extractions are limited only to very light nuclei, i.e. mass number A ≤ 4, due to computation costs and, more severely, due to several fundamental difficulties. We propose an alternative...
Libertad Barrón-Palos
(Universidad Nacional Autónoma de México, Ciudad de Mexico)
30/06/2015, 09:25
Talk
The measurement of very small parity-violating (PV) observables in few-nucleon systems, where nuclear wave functions are calculable, is a via for understanding the hadronic weak interaction (HWI), which remains enigmatic due to the dominance of the strong interaction in hadronic systems and the non-perturbative nature of Quantum Chromodynamics at low energies. Additionally, the study of the...
Rocco Schiavilla
(Jefferson Lab/Old Dominion University, Norfolk)
30/06/2015, 10:05
Talk
A status report on chiEFT studies of light-nuclei electro-weak structure and dynamics is provided, including electromagnetic elastic form factors of few-nucleon systems, magnetic moments and M1 radiative widths in A=6-10 nuclei, the pp weak fusion and muon weak captures on deuteron and 3He, and a number of parity-violating processes induced by hadronic weak interactions.
Francesca Sammarruca
(University of Idaho, Moscow)
30/06/2015, 11:10
Talk
The equations of state of nuclear and neutron matter (and, more generally, neutron-rich matter) play a fundamental role towards the understanding of a broad spectrum of systems, ranging from the skins of neutron-rich nuclei to the structure of compact stars.
After a brief introduction on different approaches to the properties of nuclear/neutron matter, we will focus on error quantification...
Silas Beane
(University of Washington, Seattle)
30/06/2015, 11:50
Talk
I will review recent calculations of the properties and interactions of nuclei and hypernuclei from first principles using lattice QCD. Many interesting observables have now been computed at several (unphysical) values of the quark masses and the first rudimentary extrapolations to the physical point have been performed. The resulting picture of the quark mass dependence of nucleon and nuclear...
Evgeny Epelbaum
(Ruhr University, Bochum)
30/06/2015, 12:30
Talk
Chiral effective field theory provides a systematically improvable perturbative approach to deriving nuclear forces in harmony with the symmetries of QCD. Combined with modern few- and many-body methods, this framework represents a commonly accepted procedure for ab initio studies of nuclear structure and reactions. Recently, a new generation of nucleon-nucleon (NN) forces up to fifth order in...
Shuangshi Fang
(Institute of High Energy Physics, Bejing)
30/06/2015, 14:30
The BESIII Experiment at the Beijing Electron Positron Collider (BEPCII) has accumulated the world's largest samples of e+e- collisions in the tau-charm region. From a sample of 1.3 billions J/psi decays, BESIII has produced many new results in the decays of eta and eta'. This talk will review the current status of these analyses, especially on the Dalitz plot of eta/eta', observations of...
Jacobo Ruiz de Elvira
(HISKP, University of Bonn)
30/06/2015, 14:30
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
Starting from hyperbolic dispersion relations for the invariant amplitudes of πN scattering together with crossing symmetry and unitarity, we derive and solve a closed system of integral equations for the partial waves of both s-channel (πN → πN) and t-channel (ππ →NN) reactions, called Roy-Steiner equations. Special attention is given to the possible sources of uncertainties and to the...
Ashot Gasparyan
(Ruhr University, Bochum)
30/06/2015, 14:30
Nucleon-nucleon interaction is studied using relativistic form of the chiral Lagrangian. Partial-wave amplitudes are computed in chiral perturbation theory at next-to-next-to-leading order in the subthreshold region. The most general constraints set by analyticity and unitarity are implemented to extrapolate the amplitudes into the physical region using the method developed in Refs. [1,2]....
Ruprecht Machleidt
(University of Idaho, Moscow)
30/06/2015, 14:45
We have calculated the nucleon-nucleon (NN) interaction up to sixth order (N5LO) of chiral perturbation theory [1,2]. Previous calculations [3] extended only up to N3LO (fourth order) and typically showed a surplus of attraction, particularly, when the πN LECs from πN analysis were applied consistently. Furthermore, the contributions at N2LO and N3LO are both fairly sizeable, thus, raising...
Hermann Krebs
(Ruhr University Bochum)
30/06/2015, 15:00
Three-nucleon forces play very important role in few and many-body simulations of nuclei/nuclear reactions at low energy. Knowledge of their precise form might lead to resolution of long standing puzzles in few-nucleon physics (e.g. Ay-puzzle in elastic nucleon deuteron scattering). Chiral effective field theory provides a systematically improvable tool for their calculation. By now...
Dmitrij Siemens
(Ruhr University, Bochum)
30/06/2015, 15:00
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
In my talk, I will focus on the reactions πN->πN and πN->ππN, which are studied at one-loop level in the frameworks of covariant and heavy baryon chiral perturbation theory. Performing combined fits to determine the relevant low-energy constants, predictions are made for various observables. In addition, first attempts to include ∆(1232) and R(1440) as explicit degrees of freedom will be...
Marián Kolesár
(IPNP, Charles University, Prague)
30/06/2015, 15:00
The eta to 3pi decays are a valuable source of information on low energy QCD. Yet they were not used for an extraction of the three flavor chiral symmetry breaking order parameters until now. We use a bayesian approach in the framework of resummed chiral perturbation theory to extract information on the quark condensate and pseudoscalar decay constant in the chiral limit, as well as the mass...
Luca Girlanda
(Universita del Salento, Lecce & INFN-Lecce)
30/06/2015, 15:15
Despite long-lasting efforts in the determination of a realistic three-nucleon force (TNF), none of the presently available models leads to a satisfactory description of bound and scattering states of the $A=3$ system. It seems natural to ascribe the above situation to the fact that these models include a very small number of adjustable parameters, compared to the two-nucleon interaction...
Bachir Moussallam
(IPN, Université Paris-Sud)
30/06/2015, 15:20
The isospin violating eta->3pi decays are expected to provide the best observables for the determination of the u-d quark mass difference. However, using the chiral expansion of the Eta -> 3Pi amplitude in the physical region has proved problematic, as it fails to reproduce the recent precise measurements of the Dalitz plot parameters. In order to circumvent this problem, it was proposed to...
Lewis Tunstall
(University of Bern)
30/06/2015, 15:20
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
Current limits from dark matter direct-detection experiments place a powerful constraint on the parameter space of the Minimal Supersymmetric Standard Model (MSSM). The interpretation of these limits, however, depends sensitively on the hadronic uncertainties associated with the scattering of supersymmetric dark matter particles off nucleons. For spin-independent scattering, we review the...
Henryk witala
(Jagiellonian University, Krakow)
30/06/2015, 15:30
Comparison of theoretical predictions based on a nucleon-nucleon potential with data for elastic nucleon-deuteron (Nd) scattering and nucleon induced deuteron breakup reveals the importance of the three-nucleon force (3NF). Inclusion of semi-phenomenological 3NF models into calculations in many cases improves the data description. However, some serious discrepancies remain even when 3NF is...
Pere Masjuan
(Johannes Gutenberg University, Mainz)
30/06/2015, 15:40
A detailed and systematic study of the η − η mixing in Large-Nc ChPT will be presented [1], with special emphasis on the role of the next-to-next-to-leading order contributions in the combined p^2 and N_c expansion. At such order, loop corrections as well as OZI-violating pieces are relevant for an appropriate and stable numerical result for the mixing angle. Pseudoscalar masses as well as...
Vincent Mathieu
(Indiana University, Bloomington)
30/06/2015, 15:40
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
The Joint Physics Analysis Center gathers theorists working on tools development for the analysis of hadon spectroscopy experiments. Our aim is to provide to experimentalists flexible amplitudes to fit data and easily extract the physics of a specific reaction. I will report on the latest results including pion-nucleon and kaon-nucleon elastic scattering, eta/omega/phi mesons decays in three...
Elzbieta Stephan
(University of Silesia, Katowice)
30/06/2015, 15:45
Systems of three nucleons can serve as a validation tool for the modern approaches to describe nuclear interaction. At the first stage the investigations were mainly focused on elastic nucleon-deuteron scattering, slowly extending to systematic measurements of the deuteron breakup reaction [1,2,3]. Intermediate energies, below the threshold for pion production, deserve special attention: it is...
Simona Giovannella
(INFN-LNF)
30/06/2015, 16:20
The KLOE experiment has collected 2.5 fb-1 at the peak of the phi resonance at the e+e- collider DAPHNE in Frascati.
The V-->Pgamma Dalitz decays, associated to internal conversion of the photon into a lepton pair, are not well described by the Vector Meson Dominance (VMD) models, as in the case of the process omega --> pi0 mu+ mu-, measured by the NA60 collaboration. The only existing data...
Johan Bijnens
(Lund University)
30/06/2015, 16:20
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
The talk will give an overview of the work done recently in calculating leading logarithms to high order and the underlying methods used. The method used [1,2] will be done and an over view of applications which have been done to very high order in the massless case and up to seven loops in the massive case [3,4,5]. The talk will concentrate mainly on the new aspects needed for the nucleon...
Daniel Phillips
(Ohio University, Athens)
30/06/2015, 16:20
I will show that combining effective field theories (EFTs) with Bayesian data analysis facilitates the rigorous quantification of theoretical uncertainties [1]. Bayesian methods are sometimes attacked on the grounds that the use of priors produces a subjective result. I will argue that, in fact, incorporating priors in the analysis permits the consistent application of analysis assumptions...
Harald W. Griesshammer
(George Washington University, Washington)
30/06/2015, 16:45
The past few years have witnessed a renewed emphasis of the need to quantify residual theoretical uncertainties [1,2]. Ideally, “double-blind” calculations would assess them based on input and method, and not by comparison to data. This is particularly important if data is absent or its consistency needs to be checked. Effective Field Theories promise a well-defined scheme to provide such...
Brian Tiburzi
(City College of New York)
30/06/2015, 16:50
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
Techniques to compute hadron properties from lattice QCD rely upon the limit of long time separation. For baryons, the signal-to-noise problem often restricts one to time separations that are not ideally long, and for which couplings to excited states can obstruct the isolation of ground-state baryon properties. We consider excited-state contamination in nucleon two- and three-point...
David Greynat
(INFN-Naples)
30/06/2015, 16:50
We will show how it is possible to implement a chiral symmetry breaking mechanism in soft-wall model of holographic QCD. We show also that it is possible to reproduce the exact Operator Product Expansion and the Regge spectra of the vector-vector and axial-axial correlators in the Large Nc limit. This method provides a nice way to perform the analytic continuation of the OPE and to predict the...
Johann Haidenbauer
(IKP, Forschungszentrum Juelich)
30/06/2015, 17:00
We present results for the in-medium properties of a hyperon-nucleon (Y N) interaction derived within chiral effective field theory (EFT) and fitted to ΛN and ΣN scattering data. The single-particle potentials for the Λ and Σ hyperons in nuclear matter are evaluated in a conventional G-matrix calculation, and the Scheerbaum factor associated with the hyperon-nucleus spin-orbit interaction is...
Xiu-Lei Ren
(Beihang University/IPN Orsay)
30/06/2015, 17:10
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
We report on a recent study of the ground-state octet baryon masses and sigma terms in the covariant baryon chiral perturbation theory (ChPT) with the extended-on-mass-shell (EOMS) renormalization scheme up to next-to-next-to-next-to-leading order (N3LO). To take into account lattice QCD artifacts, the finite-volume corrections (FVCs) and finite lattice spacing discretization effects are...
Pablo Sanchez Puertas
(Johannes Gutenberg University, Mainz)
30/06/2015, 17:10
Pseudoscalar-meson decays (π0, η, η ) into lepton pairs (e+e−, µ+µ−) are unique in its kind as they probe the neutral pseudoscalar meson structure in the whole energy-range. This structure, which is encoded in the doubly virtual transition form factor (TFF) governing their interactions with two photons, needs a complete energy description. In this work, we identify the relevant energy regimes...
Yordanka Ilieva
(University of South Carolina, Columbia)
30/06/2015, 17:15
Theoretical studies suggest that experimental observables for hyperon production reactions can place stringent constraints on the free parameters of hyperon-nucleon potentials, which are critical for the understanding of hypernuclear matter and neutron stars. We will present preliminary experimental results for the polarization observables Σ, Py, Ox, Oz, Cx, and Cz for final-state interactions...
Xian-Wei Kang
(IAS and IKP, Forschungszentrum Jülich)
30/06/2015, 17:30
The recent development of the antinucleon-nucleon (N-bar N) interaction in chiral effective
field theory [1] will be reported and the phenomenological meson-exchange models (taking Julich model as an example) will be mentioned as well. With such potentials and the distorted-wave Born approximation, we examine the influence of the antiproton-proton (p-bar p) interaction on the mass spectrum in...
Jambul Gegelia
(Forschungszentrum Jülich)
30/06/2015, 17:30
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
We suggest an extension of the one-nucleon sector of baryon chiral perturbation theory beyond the low-energy region. Applicability of the proposed approach for higher energies is restricted to small scattering angles, i.e. the kinematical region where the quark structure of hadrons cannot be resolved. The main idea is to re-arrange the low-energy effective Lagrangian according to a new power...
Alessandro Rizzo
(INFN-Roma2)
30/06/2015, 17:30
The study of the hadronic spectrum is one of the most powerful tools to investigate the mechanism at the basis of quark confinement within hadrons. A precise determination of the spectrum allows not only to asses the properties of the hadrons in their fundamental and excited states, but also to investigate the existence of states resulting from alternative configurations of quarks and gluons...
Domenico Logoteta
(INFN-Pisa)
30/06/2015, 17:45
We calculate the energy per particle of symmetric nuclear matter and pure neutron matter using the many-body Brueckner-Hartree-Fock (BHF) approach and employing the Chiral Next-to-next-to-next-to leading order (N3LO) nucleon-nucleon (NN) potential supplemented with various parametrizations of the Chiral Next-to-next-to leading order (N2LO) three-nucleon force. Such combination is able to...
Bingwei Long
(Sichuan University, Chengdu)
30/06/2015, 17:50
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
As the pion mass approaches a critical value m_pi^star, an S-wave baryon resonance can cross pion-baryon threshold, thus driving the scattering length to diverge. Charmed baryon resonance Lambda_c^+(2595) appears to be a realization of such a system. I explore the consequences of chiral symmetry for m_pi near m_pi^star, which are all centered around the finding that if m_pi^star is not too...
Olga Shekhovtsova
(IFJ PAN, Krakow)
30/06/2015, 17:50
TAUOLA is a Monte Carlo generator dedicated to generating tau-lepton decays and it is used in the analysis of experimental data both at B-factories and LHC. TAUOLA is a long term project that started in the 90's and has been under development up to now. In the last years substantial progress for the simulation of the process: tau-> 3pions nu_tau was achieved. It is related with a new...
Betzalel Bazak
(Racah Institute of Physics, The Hebrew University of Jerusalem)
30/06/2015, 18:00
Recently, Tan suggested that the properties of universal quantum gases depend on a new characteristic quantity, called the contact. The contact describes the probability of two particles coming close to each other, i.e. it is a measure of the number of close particle pairs in the system. Utilizing the contact, this theory predicts the energy, pressure and other properties of the system. It was...
Rafel Escribano
(Autonomous University of Barcelona)
30/06/2015, 18:10
Goldstone Boson Working Group
Talk
In a combined study of the decay spectra of τ−→KSπ−ντ and τ−→K−ηντ decays within a dispersive representation of the required form factors, we illustrate how the K∗(1410) resonance parameters, defined through the pole position in the complex plane, can be extracted with improved precision as compared to previous studies. While we obtain a substantial improvement in the mass, the uncertainty in...
Maarten Golterman
(San Francisco State University)
30/06/2015, 18:10
We determined the NLO chiral low-energy constant L_10, and various combinations of NNLO chiral low-energy constants employing recently revised ALEPH results for the non-strange vector (V) and axial-vector (A) hadronic tau decay distributions and recently updated RBC/UKQCD lattice data for the non-strange V-A two-point function. In this talk, we explain the ingredients of this determination. ...
Dr
Jan Friedrich
(Physik-Department E18)
01/07/2015, 08:45
Talk
COMPASS has recently completed the analysis of pion Compton scattering measured via the Primakoff effect. From the first available data set, the pion polarisability is determined with unprecedented precision. It is in agreement with the expectation from chiral perturbation theory, and in tension with the previous dedicated measurements that suggested a value about twice as large. The...
Hidenori Fukaya
(Osaka University)
01/07/2015, 09:25
Talk
In lattice QCD simulations, there is a strong tendency to over-estimate the form factors (and therefore, under-estimate the related charge radii) of pions and other hadrons. In fact, the three major systematic in lattice QCD: finite lattice spacing a, lack of chiral symmetry, and finite volume all could contribute to the over-estimation of the form factors. This can be easily understood within...
Stefan Scherer
(Johannes Gutenberg University, Mainz)
01/07/2015, 10:05
Talk
We discuss the extended on-mass-shell scheme for manifestly Lorentz-invariant baryon chiral perturbation theory. We present a calculation of pion photo- and electro-production up to and including order q^4. The low-energy constants have been fixed by fitting experimental data in all available reaction channels. Our results can be accessed via a web interface, the so-called chiral MAID...
Haiyan Gao
(Duke University, Durham)
01/07/2015, 11:10
Talk
An important goal in modern nuclear physics is to understand how one can describe the structure of nuclei and nuclear forces from first principles of quantum chromodynamics (QCD), the fundamental theory describing the strong interaction. Few-nucleon systems provide important testing grounds for state-of-the-art few-body calculations, calculations based on effective field theories, and more...
Antonin Portelli
(University of Southampton)
01/07/2015, 11:50
Talk
Isospin symmetry is explicitly broken in the Standard Model by the mass and electric charge of the up and down quarks. These effects represent a perturbation of hadronic amplitudes at the percent level. Although these contributions are small, they play a crucial role in hadronic and nuclear physics. Moreover, as lattice computations are becoming increasingly precise, it is becoming more and...
Bastian Kubis
(University of Bonn)
02/07/2015, 08:45
Talk
Ever since Weinberg's seminal predictions of the pion-nucleon scattering amplitudes at threshold, this process has been of central interest for the study of chiral dynamics involving nucleons. Quantities like the scattering lengths or the pion-nucleon sigma-term are fundamental quantities characterizing the explicit breaking of chiral symmetry by means of the light quark masses. On the other...
Kalyan Allada
(Massachusetts Institute of Technology)
02/07/2015, 09:25
Talk
Our understanding of nucleon spin structure is still far from complete. Experiments conducted at Jefferson Lab have made significant contributions to improve our knowledge of the longitudinal spin structure by measuring polarized structure functions, g1 and g2, down to Q^2 = 0.02 GeV^2. The low Q^2 data is especially useful in testing the Chiral Perturbation theory (ChiPT) calculations. The...
Vittorio Lubicz
(Roma3 University)
02/07/2015, 10:05
Talk
Recently, a method has been proposed for the first time to compute electromagnetic effects in hadronic processes using lattice simulations. The method can be applied, for example, to the leptonic and semileptonic decays of light or heavy pseudoscalar mesons. For these quantities the presence of infrared divergences in intermediate stages of the calculation makes the procedure more complicated...
Augusto Ceccucci
(CERN)
02/07/2015, 11:10
Talk
Kaons are a laboratory where a broad physics programme can be addressed. From the study of fundamental symmetries to the exploration of the hadron structure, from the search for phenomena beyond the Standard Model to the comprehension of the simplest hadronic states, many investigations profit from the remarkably clean theoretical and experimental environment provided by kaons. NA62 is a new...
Gerhard Ecker
(University of Vienna)
02/07/2015, 11:50
Talk
I will review some recent activities in mesonic chiral perturbation theory. Our present knowledge of low-energy constants in the strong sector up to and including next-to-next- to-leading order will be discussed. I will also assess the present status of CKM unitarity. Further topics are pion polarizabilities, kaon and η decays.
Robert Edwards
(Jefferson Lab)
02/07/2015, 12:30
Talk
There has been recent, significant, advances in the determination of the meson spectrum of QCD. Current efforts have focused on the development and application of finite-volume formalisms that allow for the determination of scattering amplitudes as well as resonance behaviour in coupled channel systems. I will review some of these recent developments, and demonstrate the viability of the...
Masayasu Hasegawa
(Joint Institute for Nuclear Research, Moscow)
02/07/2015, 13:10
In previous works we have shown the relation between chiral symmetry breaking, instantons, and monopoles by adding the monopoles to quenched SU(3) configurations [1,2]. We found that (i) one pair of monopoles makes one instanton. (ii) the monopole pair induces chiral symmetry breaking. This was done by measuring the chiral condensate computed from the eigenvalues and eigenvectors of the Overlap...
Frederic Brünner
(Vienna University of Technology)
02/07/2015, 13:10
I present new results on glueball decay rates in the Sakai-Sugimoto model, a holographic top-down approach for QCD with chiral quarks based on a probe-brane construction within Witten’s holographic model of nonsupersymmetric Yang-Mills theory. We calculated [1] rates for decays into two pions, two vector mesons and four pions, using a range of the ’t Hooft coupling which closely reproduces the...
Jordi Maneu
(University of Barcelona)
02/07/2015, 13:10
Since the discovery in 1952 of the first strange fragment in emulsion chamber experiments, many efforts have been put in extending our knowledge of the nuclear chart, including the SU(3) sector. Worldwide, the study of the interactions among nucleons and hyperons has been a priority in the research plan of many experimental facilities. After more than sixty years of Λ-hypernuclear studies,...
Astrid Hiller Blin
(IFIC, University of Valencia)
02/07/2015, 13:10
We present the calculation of the hyperon forward spin polarizability gamma0 using manifestly Lorentz covariant baryon chiral perturbation theory including the intermediate contribution of the isospin-3/2 states. As at the considered order the extraction of gamma0 is a pure prediction of chiral perturbation theory and does not depend on renormalization schemes, the obtained values are a good...
AlaaEldeen Elmeshenb
(Jagiellonian University, Krakow)
02/07/2015, 13:10
The study of few-nucleon system is interesting and important. It gives a microscopic description of complex systems within the framework of modern concepts of nucleon-nucleon and many-body interactions. Using the muon capture process is an ideal tool to study few-nucleon systems. In this work we plan to investigate the µ− + d → ν_µ + n + n capture reaction. This reaction is interesting for...
Xiu-Lei Ren
(Beihang University/ IPN Orsay)
02/07/2015, 13:10
Understanding the nature of the Roper resonance is of particular interest. Its mass, for example, shows a very unusual pattern: it is lower than the negative parity state N(1535). Also, the Roper is expected to play a role in low energy observables due to its closeness to the nucleon and Delta(1232).
We report on a systematic study of the nucleon, Delta(1232), and Roper masses in heavy...
Sergi González-Solís
(IFAE-Autonomous University of Barcelona)
02/07/2015, 13:10
I will analyze the anomalous single and double Dalitz decays of the neutral pseudoscalar mesons, P → l+ l− γ and P → l+ l− l+ l− (P = π , η, η' ; l= e or µ), employing a model-independent transition form factor (TFF) of the Pγ∗γ(∗) vertices built up, through the use of rational approximants, from the current experimental data of the space-like TFF γ∗γ → P. Predictions for the branching ratios...
Rod Crewther
(University of Adelaide)
02/07/2015, 13:10
We observe that flavor current conservation constrains the structure of chiral-scale perturbation theory ChPT_sigma. This theory addresses the disagreement between experiment and lowest order chiral SU(3) x SU(3) perturbation theory (ChPT_3) for amplitudes involving the f_0(500) resonance and O(m_K) extrapolations in momenta. In ChPT_sigma, it is assumed that 3-flavor QCD has an infrared fixed...
Thomas Wolkanowski-Gans
(Goethe-Universität Frankfurt am Main)
02/07/2015, 13:10
A way to understand the light scalar sector of hadron physics is by applying a type of dynamical generation in which additional resonances arise as companion poles from quark-antiquark seed states by incorporating mesonic loops at the level of S-wave propagators [1−3]. Along this line, we first repeat and complete the calculations of previous works of Tornqvist and Roos (TR) and Boglione and...
Khepani Raya
(University of Michoacan, Morelia)
02/07/2015, 13:10
We present recent advances in the study of the Pion structure through Dyson-Schwinger Equations, the equations of motion of QCD. In particular, we discuss the neutral pion to two photons transition form factor, a problem which involves careful parametrizations of the quark propagator and Bethe-Salpeter Amplitudes. This calculation is relevant for future experiments to be conducted at Belle II.
Ulf-G. Meissner
(HISKP, University of Bonn)
02/07/2015, 14:30
In this talk, I discuss the emergence of clustering in ab initio nuclear lattice simulations. The spectrum and the structure of the 12C and 16O nuclei are displayed. I also consider some issues related to the breaking of rotational symmetry in alpha cluster-models and show how these lattice artifacts can be tamed.
Luciano Libero Pappalardo
(INFN-Ferrara)
02/07/2015, 14:30
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
In the context of rapid theoretical developments in non-perturbative QCD, a formalism of Transverse Momentum Dependent parton distribution functions (TMDs) and of Generalized Parton Distributions (GPDs) was introduced in the last two decades, providing a more comprehensive multi-dimensional description of the nucleon. TMDs and GPDs allow in fact for complementary descriptions of the nucleon in...
Jose Manuel Alarcon
(University of Bonn)
02/07/2015, 14:55
In this talk I want to present the recent progresses in neutron-proton scattering on the lattice with Lattice EFT. Among them, the study of the different lattice actions in describing the scattering observables and binding energy of the deuteron. The convergence of the chiral series for these observables will be analyzed as well, and will be shown to be in good agreement with the expected...
Ignasi Rosell
(Universidad CEU Cardenal Herrera, Valencia)
02/07/2015, 15:00
We study strongly coupled models of electroweak symmetry breaking with a light Higgs boson. We use a resonance effective Lagrangian with bosonic massive resonances together with the Standard Model degrees of freedom, including a light Higgs. We consider constraints from the phenomenology and from the assumed high-energy behavior of the underlying theory. This resonance effective theory can be...
Ryan Zielinski
(University of New Hampshire, Dover)
02/07/2015, 15:00
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
The Jefferson Laboratory accelerator has been used to great effect in the study of the polarized structure of nucleons. Measurements of the spin-dependent structure functions have been proven to be powerful tools in testing the validity of effective theories of Quantum Chromodynamics. While the neutron spin structure functions, g1n and g2n , and the longitudinal proton spin structure function,...
Alexander Rokash
(Ruhr University, Bochum)
02/07/2015, 15:10
The adiabatic projection method is a general framework for obtaining low-energy effective Hamiltonian for clusters. Previous studies [1,2] have used the adiabatic projection method in combination with the finite-volume energy Luscher method to extract scattering phase shifts. We discuss several methods to calculate elastic phase shifts directly from asymptotic cluster wave functions obtained...
Peter Stoffer
(HISKP, University of Bonn)
02/07/2015, 15:20
The anomalous magnetic moment of the muon (g −2)µ has been measured and computed to very high precision of about 0.5 ppm. For more than a decade, a discrepancy has persisted between experiment and Standard Model prediction, now of about 3σ. The main uncertainty of the theory prediction is due to strong interaction effects. With the expected improvement of the input for hadronic vacuum...
Carlos Granados
(Uppsala University)
02/07/2015, 15:20
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
The transverse densities of charge and magnetization in the nucleon are studied at peripheral transverse distances (~O(M_pi^-1)), where they are dominated by chiral dynamics and can be calculated model-independently using ChEFT. The densities are represented as overlap integrals of chiral light-front wave functions, describing the transition of the initial nucleon to soft pion-nucleon (and...
Serdar Elhatisari
(University of Bonn)
02/07/2015, 15:25
We present ab initio lattice calculations of alpha-alpha clusters scattering at next-to-next-to-leading order in chiral effective field theory using the adiabatic projection method. The adiabatic projection method is a general framework for scattering and reactions on the lattice which uses a set of initial cluster states and Euclidean time projection to give a systematically improvable...
Manuel Pavon Valderrama
(IPN Orsay)
02/07/2015, 15:40
Effective field theories are generic descriptions of low-energy phenomena for which a fundamental theory is unknown or impractical to solve. The formulation of EFTs is grounded on symmetries and power counting. While symmetries provide the connection with the underlying theory, power counting -- how to order the effective interactions from more to less relevant -- makes EFTs predictive and...
Yu-Chen TUNG
(University of Chicago)
02/07/2015, 15:40
KOTO at J-PARC is the dedicated experiment to probe the KL➞π0νν decay, which is considered as a golden decay as its clean theoretical branching ratio and potential to test the standard model and physics beyond it. After J-PARC restoring from the radiation accident in 2013, KOTO has already started data taking, aiming to reach the standard model sensitivity of O(10^-11) in three years. We will...
Philipp Wein
(University of Regensburg)
02/07/2015, 15:40
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
We present a leading one-loop calculation in the framework of three-flavor baryon chiral perturbation theory (BChPT) for three-quark light-cone distribution amplitudes, which parametrize the momentum distribution in the leading Fock state and are relevant for the description of hard exclusive processes. Such a calculation automatically yields model-independent results for the leading SU(3)...
Waseem Kamleh
(University of Adelaide)
02/07/2015, 16:20
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
We present lattice QCD results showing that the strange magnetic form factor of the Lambda(1405) vanishes, signaling the formation of an antikaon–nucleon. Together with a Hamiltonian effective-field-theory model analysis of the lattice QCD energy levels, this strongly suggests that the structure is dominated by a bound antikaon-nucleon component. This result clarifies that not all states...
Xu Feng
(Columbia University, New York)
02/07/2015, 16:20
The rare kaon decays, K → πν¯ν, have attracted increasing interest during the past few
decades. As flavor changing neutral current processes, these decays are highly suppressed in the standard model and thus provide ideal probes for the observation of new physics effects. As second-order weak interactions, the ultra-rare decays K → πν¯ν represent a significant challenge in experiments. After 40...
Franz Gross
(Jefferson Lab)
02/07/2015, 16:20
Until recently, precision calculations of the deuteron quadrupole moment, Qd, have consistently under-predicted its value by several percent, leaving the calculation of this quantity an "unresolved problem" in few body physics. I will report on two recent calculations that predict Qd to better than 1%. One of these uses chiral effective field theory and the other uses the covariant spectator...
Lauro Tomio
(Federal University of ABC, Sao Paolo)
02/07/2015, 16:35
Renormalized fixed-point Hamiltonians are formulated for systems described by interactions that originally contain point-like singularities (as the Dirac-delta and/or its derivatives). They express the renormalization group invariance of quantum mechanics. The approach has been applied in the study low-energy scattering observables, such as the nucleon-nucleon interaction with one pion...
Sinya Aoki
(Kyoto University)
02/07/2015, 16:50
We discuss the fate of the axial U(1) symmetry in 2-flavor QCD, when the non-singlet chiral symmetries are recovered at finite temperature. We theoretically investigate the constraints on the eigenvalue density of the Dirac operator, derived from the non-singlet chiral symmetries among various multi-point correlation functions in the chiral limit. We show that the axial U(1) symmetry, broken...
Maxim Mai
(HISKP, University of Bonn)
02/07/2015, 16:50
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
A chiral unitary approach for antikaon-nucleon scattering in on-shell factorization is studied. We find multiple sets of parameters for which the model describes all existing hadronic data similarly well. We confirm the two-pole structure of the Λ(1405). The narrow Λ(1405) pole appears at comparable positions in the complex energy plane, whereas the location of the broad pole suffers from a...
Nodoka Yamanaka
(iTHES Research Group, RIKEN)
02/07/2015, 16:50
The nuclear electric dipole moment is a very sensitive probe of CP violation beyond the standard model, and for light nuclei, it can be evaluated accurately using the few-body calculational methods. In this work, we evaluate the electric dipole moment of the deuteron, $^3$He, $^3$H, $^6$Li, and $^9$Be in the Gaussian expansion method with realistic nuclear force, and assuming the one-meson...
Roman Skibinski
(Jagiellonian University, Krakow)
02/07/2015, 17:05
In the recent decade the chiral Effective Field Theory (χEFT) has proven its predictive power in low energy nuclear physics. Within this approach the two- and three-nucleon (3N) forces have been derived perturbatively in a consistent manner [1,2]. The three-nucleon force (3NF) occurs for the first time at the next-to-next-to leading order (N2LO) of chiral expansion. Inclusion of N2LO 3NF to...
Daniel Robaina
(Institute of Nuclear Physics, Mainz)
02/07/2015, 17:10
We investigate the low-temperature phase of strongly interacting matter and the crossover region with two light flavors of quarks in Lattice QCD. Based on Chiral Ward Identities we test the applicability of a fixed-temperature chiral expansion given that chiral symmetry is spontaneously broken. It indicates that a sharp real-time excitation persists with the quantum numbers of the pion...
Albert Feijoo
(University of Barcelona)
02/07/2015, 17:10
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
The meson-baryon interaction in the S=-1 sector is studied by means of a chiral SU(3) Lagrangian up to next-to-leading order, implementing unitarization in coupled channels. The parameters of the Lagrangian have been fitted to a large set of experimental data in two-body channels. We focused on K- p --> K Cascade reactions because they show the strongest sensitivity to the next-to-leading...
John Annand
(University of Glasgow)
02/07/2015, 17:20
An experiment to measure the differential cross section for Compton scattering from 3He and 4He at the MAMI tagged photon facility in Mainz is described. The objective is to measure the isoscalar nucleon electromagnetic polarisabilities and thus access the neutron polarisabilities. The experiment will use a high-pressure gas-scintillator active target to measure recoiling He ions in...
Raquel Molina
(The George Washington University, Washington)
02/07/2015, 17:30
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
The Λ(1405) baryon is of continued interest in hadronic physics, being absent in many quark model calculations and supposedly manifesting itself in a two-pole structure. Finite- volume Lattice-QCD eigenvalues for different quark masses were recently reported by the Adelaide group [1]. We compare these eigenvalues to those of a unitary Chiral Perturbation Theory (UχPT) model [2], evaluated in...
Aron Bernstein
(Massachusetts Institute of Technology, Cambridge)
02/07/2015, 17:30
The pi^0 rightarrow gamma gamma decay rate is dominated by the QCD axial anomaly that is increased by approx 4.5% +- 1.0% by the mixing of the pi^0 wave function with the eta, eta^' mesons. This relatively large isospin breaking effect is proportional to the mass difference of the up and down quarks. It has been calculated in Chiral Perturbation Theory (ChPT) by three slightly different...
Saori pastore
(University of South Carolina, Columbia)
02/07/2015, 17:35
In this talk, I will present a number of Quantum Monte Carlo calculations of electromagnetic observables in light nuclei (A<=10) including electromagnetic moments, M1 and E2 transitions. These calculations use wave functions generated from nuclear Hamiltonians with two- and three-nucleon realistic potentials. In addition to impulse approximation terms, nuclear electromagnetic currents ...
Berhan Demissie
(George Washington University, Washington)
02/07/2015, 17:50
Compton scattering processes are ideal to study electric and magnetic dipole polarizability coeffcients of nucleons [1]. These fundamental quantities parametrize the response to a monochromatic photon probe. In this work, the inelastic channel γd → γnp is treated in χEFT, with a focus on the NQFP - neutron quasi-free peak - kinematic region. In this region, the momentum of the outgoing proton...
Ashot Gasparian
(North Carolina A&T State University, Greensboro)
02/07/2015, 17:50
The neutral pion is the lightest strongly interacting particle in Nature. Therefore, the properties of $\pi^0$ decay are especially sensitive to the underlying fundamental symmetries of quantum chromodynamics (QCD). In particular, the pi^0 -> gamma gamma decay width is primarily defined by the spontaneous chiral symmetry breaking effect (chiral anomaly) in QCD. Theoretical activities in this...
Parikshit Junnarkar
(Helmholtz Institut, Mainz)
02/07/2015, 17:50
Hadron Structure and Meson-Baryon Interaction Working Group
Talk
We present preliminary results from a lattice QCD calculation of the H-dibaryon using two flavors ofO(a) improved Wilson fermions. We employ six quark interpolating operators with the appropriate quantum numbers of the H-dibaryon and also explore its couplings to two-baryon channels. We apply two smearings to improve the overlap to the ground state, which is obtained by solving a generalised...
Karol Kampf
(Charles University, Prague)
02/07/2015, 18:10
In this talk I will present basic properties of the lightest meson, pi0. I will discuss its decay modes, mainly two photon decay, Dalitz decay and e+e- production and focus on its recent theoretical and experimental studies. Connection with the theoretical calculation of the hadronic light-by-light scattering contribution in the g-2 type experiment will be outlined.
Gilberto Colangelo
(University of Berne)
03/07/2015, 08:45
Talk
I will describe recent progress in approaching the calculation of the hadronic light-by-light contribution to (g-2)_mu with dispersive methods. I will first discuss general properties of the four-point function of the electromagnetic current in QCD, its Lorentz decomposition and dispersive representation. For what concerns the pseudoscalar pole contributions, I will give an overview of the...
Tom Blum
(University of Connecticut, Storrs)
03/07/2015, 09:25
Talk
Recent studies of the hadronic vacuum polarization and hadronic light-by-light scattering contributions to the muon anomalous magnetic moment (g-2) are reviewed. Attention is paid to systematic errors arising from finite volume and non-zero lattice spacing, among others. The problem of disconnected quark loop diagrams is also discussed.
Simon Eidelman
(Budker Institute of Nuclear Physics, Novosibirsk)
03/07/2015, 10:05
Talk
We discuss the current status of the theoretical prediction for the muon anomalous magnetic moment in Standard Model. Recent developments in estimation of hadronic vacuum polarization are described based on measurements of e+ e− → hadrons cross section in Novosibirsk and Beijing as well as those with ISR at KLOE, BaBar and Belle. We also briefly review expectations for experiment and theory in...
Martha Constantinou
(University of Cyprus, Nicosia)
03/07/2015, 11:10
Talk
Understanding hadron structure from first principles is considered a milestone of hadronic physics and numerous experiments have been devoted to its study, starting with the measurements of the electromagnetic form factors more than 50 years ago. Lattice QCD (LQCD) is a powerful tool for the ab inition calculation of hadron observables that are either well determined experimentally, or not...
Evangeline Downie
(George Washington University, Washington)
03/07/2015, 11:50
Talk
Polarizabilities are fundamental properties of the nucleon which can be accessed by measuring the differential cross section, and singly and doubly polarized asymmetries in real Compton scattering (RCS). Their measurement gives rise to a better understanding of nucleon dynamics and structure. Polarizabilities play an important role in many areas of physics: from being the largest component...
Judith McGovern
(University of Manchester)
03/07/2015, 12:30
Talk
We have recently completed a high-precision extraction of the proton spin-independent polarisabilities from the world database of low-energy Compton scattering experiments, within the framework of chiral effective field theory (χEFT) with pions, nucleons, and the Delta(1232) as explicit degrees of freedom [1]. Our Baldin-sum-rule-constrained results are [2]
α_p = 10.65 ± 0.35(stat) ±...
