In this talk I will discuss photon measurements i) as tests of pQCD and
used to tune PDFs ii) providing important information for BSM searches, and
iii) related with the Higgs Boson. I will go over LHC and non-LHC results
and give prospects for HL-LHC and beyond.
In this talk we will review some recent progress on light quark spectroscopy
coming from $\eta$ and $\eta$' physics.
I will review the status of heavy quark spectroscopy, in particular the XYZ and pentaquark candidates.
Various measurements of photoproduction in lepton-nucleon interactions are presented, along with their theoretical interpretations. These include spin-independent measurements of inclusive charm and beauty production, isolated photons and jets as well as exclusively produced hadrons. Results of hadron photoproduction in data taken with polarised leptons and nucleons are shown also.
There may exist new sub-GeV particles, χ, which are electrically neutral but couple to the electromagnetic current via higher-dimensional operators. This talk focus on the possible detection of light state coupled to the photon through magnetic- and electric-dipole moments, or carrying an anapole moment or charge radius.
New constraints, as well as future sensitivities, on the existence of...
In this talk we review the recent progress on the numerical determination of the hadronic contributions to the anomalous magnetic moment of the muon and we discuss the role of experimental data on the accuracy of its determination. Special emphasis on the light-by-light scattering contribution and on its main contribution, the pseudoscalar piece, is made. A state-of-the-art deviation between...
The gravitational form factors of hadrons can be studied through hard-exclusive reactions, give access to the "last global unknown property" D-term, and promise insights on the internal forces inside hadrons from a unique perspective through their interpretation in terms of energy-momentum tensor densities. The current experimental and theoretical status is reviewed.
Measurement of open charm and beauty production cross sections in ep deep inelastic scattering (DIS) at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections are obtained in a restricted kinematic range. Perturbative QCD calculations are compared to the combined data. Next-to-leading order QCD analysis is performed using these data together with combined inclusive HERA...
We study process e+e- -> e+e-eta' in the double-tag mode and measure for the first time the gamma gamma -> eta' formfactor
F(Q^2_1,Q^2_2) in the momentum-range 2 < Q^2_1,Q^2_2 < 60 GeV^2. The analysis is based on data with an integrated luminosity
469 fb^-1 collected at the PEP-II e+e- collider with the BABAR detector at center-of-mass energies near 10.6 GeV. The results for the formfactor...
Motivated by the recent developments in data-driven approaches to improve the hadronic light-by-light scattering calculations of the Standard Model prediction of the anomalous magnetic moment of the muon $a_\mu$, the BESIII collaboration has embarked on a dedicated two-photon physics program. The momentum dependence of transition form factors of single pseudoscalar mesons, as well as of...
We present the observation of the light-by-light scattering process, γγ → γγ, in lead-lead collisions at √sNN = 5.02 TeV. The analysis is conducted using 1.73nb-1 of data collected in November 2018 by the ATLAS experiment at the LHC. Light-by-light scattering event candidates are selected in events with two photons produced exclusively, with small diphoton transverse momentum and small...
Measurements with photon-photon collisions in CMS are reviewed.
Magnetic monopoles are present in generic classes of models beyond the Standard Model and there are currently searches underway for them at the LHC. The strong magnetic fields present in peripheral heavy ion collisions can produce monopoles by the (dual) Schwinger effect. I will outline recent progress in understanding this process and argue that heavy ion collisions may be the most...
So far light-by-light scattering ($\gamma\gamma\to\gamma\gamma$) was not accessible for experiments because the corresponding cross section is rather low. Measurements of diphotons in ultra-peripheral collisions (UPCs) of lead-lead have been reported recently by the ATLAS [1] and CMS Collaborations [2]. Our theoretical results based on equivalent photon approximation in the impact parameter...
In this talk we will present a brief review of the recent results for the particle production by $\gamma \gamma$ interactions at $pp/pA/AA$ collisions. In particular, the dilepton production will be discussed, as well the background associated to pomeron induced interactions. Finally, the probe of the X(4350) in $\gamma \gamma$ interactions at the LHC will be discussed.
The talk presents the LUXE experiment which plans on using the European XFEL electron beam at DESY with an energy of 17.5 GeV and a high intensity optical laser to study non-perturbative QED phenomena. The main focus of the experiment will be the measurement of the rate of laser assisted electron-positron pair production in collisions of high energy photons with an intensive laser beam and...
Photon-induced processes in proton-proton interactions have become recently very topical. The large energy at the LHC, when combined with relatively large luminosity at run II, allows to start the exploration of such processes.
We discuss production of $W^+ W^-$ pairs and $t \bar t$ quark-antiquark pairs in proton-proton collisions induced by two-photon fusion including, for a first time,...
We analyze in detail the LHC prospects for charged electroweakino searches, decaying to leptons, in compressed supersymmetry scenarios, via exclusive photon-initiated pair production. This provides a potentially increased sensitivity in comparison to inclusive channels, where the background is often overwhelming. We pay particular attention to the challenges that such searches would face in...
The analytical asymptotic cross section for arbitrary masses was given a few years ago.
Obtaining an analytical approach of the onset of the asymptotic regime is an interesting challenge.
The current status will be reviewed.
We discuss $\gamma^* \gamma^* \to \eta_c(1S)\, , \,\eta_c(2S)$ transition form factor for both virtual photons. The general formula is given. We use different models for the $c \bar c$ wave function (LFQM or the ones obtained from the solution of the Schr\"odinger equation for different $c \bar c$ potentials: harmonic oscillator, Cornell, logarithmic, power-law and Buchm\"uller-Tye).
We...
The 2015 LHCb discovery of an exotic structure (denoted by $P_c^+$) decaying in $J/\psi \,p$ and conjectured to be a penta-quark state has triggered a renewed interest in the possible existence of multiquark states not predicted by the naive quark model. In this talk we present some considerations on $P_c$ photo-production experiments, aimed at testing its multi-quark interpretation in the...
Vector mesons are plenteously produced in ultra-peripheral collisions where the impact parameter is larger than the sum of the radii of the two projectiles, implying that electromagnetic induced processes become dominant.
Light vector meson photoproduction cross sections can be used to study Glauber-Gribov shadowing effects at the hadronic level while the photoproduction of heavy vector...
The Sun is not expected to be a bright gamma-ray source above 1 GeV, due to the moderate strength of solar magnetic fields. However, the Sun may act as a passive gamma-ray source, through the hadronic interaction of galactic cosmic rays with the Solar atmosphere. The Fermi-LAT has detected a bright solar gamma-ray flux, which implies that solar magnetic fields efficiently redirect incoming...
The particle nature of dark matter remains one of the most mysterious and urgent research questions of modern particle physics and cosmology. Despite decades of research, the mass of possible dark matter particles is only constrained to within 80 orders of magnitude or so. Astronomical observations spanning the full electromagnetic spectrum allow to search for dark matter particles across the...
Axion-like particles (ALPs) are light, neutral, (pseudo-)scalar bosons predicted by several extensions of the Standard Model of particle physics such as the String Theory and are supposed to interact primarily only with two photons. In the presence of an external magnetic field photon-ALP oscillations may occur and produce sizable astrophysical effects in the very-high energy (VHE) band....
In this talk some recent results from the Pierre Auger Collaboration
will be presented. These include the measurement of the energy
spectrum of cosmic rays over a wide range of energies, studies of the
cosmic-ray mass composition with the fluorescence and surface detector
of the Observatory, studies on the anisotropies in the arrival
direction of cosmic rays at different scales and the...
An excess in the flux of cosmic positrons at Earth above 10 GeV has been measured by Pamela, Fermi-LAT and with unprecedented precision by AMS-02. The observed flux cannot be explained by the production of positrons in the spallation reaction of hadronic cosmic rays (CRs) with the interstellar medium. Various interpretations have been invoked to explain this excess, such as the production in...
The search for electromagnetic counterparts or neutrino emissions from gravitational-wave sources engages a wide scientific community. Here, we outline the pathway that led to the birth of multi-messenger astronomy with the first direct observations of the gravitational-wave signals measured to date, focusing on the new challenges of LIGO and Virgo Observing Run 3 (O3) and the beginning of the...
In 2017, ATLAS has been equipped with a new, dedicated detector system
allowing measurements of forward protons scattered at small angles in
diffractive and electromagnetic processes. These ATLAS Forward Proton
detectors (AFP) can operate during standard high-luminosity LHC runs
and collect large amounts of integrated luminosity. This gives a
possibility to study rare interactions, in...
Prospects for photon-photon measurements with CMS and TOTEM will be reviewed.
At present experiments with a new Belle II detector at SuperKEKB collider has started at KEK (Japan). These new experiments will continue and widen the studies began at the previous experiments with the Belle detector. The luminosity of the SuperKEKB collider will exceed the previous one by about 40 times, amounting to $8\times 10^{35}$cm$^{-2}$s$^{-1}$. The main features of the collider and...
We investigate the exclusive photoproduction of J/ψ mesons in ultraperipheral heavy-ion collisions in the color dipole approach.
We use the color dipole formulation of Glauber-Gribov theory to calculate the diffractive amplitude on the
nuclear target. We compare our results to recent published data on exclusive J/ψ production in ultraperipheral
lead-lead collisions at √sNN=2.76 and...
A global survey of weak mixing angle measurements at low and high energies is presented first. Then I will discuss theoretical uncertainties in precision observables with special emphasis on their correlations. The important role of vacuum polarization in global fits will also be addressed before fit results are presented.
The high-intensity setup, trigger system flexibility and detector performance make the NA62
experiment at CERN particularly suitable to perform direct searches for long-lived hidden-sector particles, such as dark photons, dark scalars, axion-like particles, and heavy neutral leptons, using kaon and pion decays as well as operating the experiment in dump mode.
Results from NA62 will be...
In high-energy hadron collisions, direct photons can be produced at different stages and are of particular interest to study the hot QCD medium since they escape it without being affected.
At high transverse momentum ($p_{\text{T}}$), their production is dominated by high-$p_{\text{T}}$ parton fragmentation and hard-scattering processes between partons. The latter can be accessed...
We review production of light neutral mesons, neutral pions and eta mesons, measured in pp, pA and AA collisions at LHC energies. Neutral meson production provides exploration of various physics topics: In pp collisions one can test pQCD predictions, study structure function in proton and fragmentation functions, and build a reference for pA and AA collisions; In pA collisions, it enables to...
Based on [1904.01044], I present recent results of a Next-to-Next-to-leading order (NNLO) calculation of inclusive isolated photon and photon-plus-jet production using the Monte-Carlo event generator NNLOJET. In order to mimic experimental photon isolation criteria we apply a staged isolation procedure. A Frixione-type isolation with small cone size is used to ensure numerical stability,...
The main purpose of the LHCf experiment is to test the hadronic interaction models used in ground based cosmic rays experiments to simulate air-showers induced by ultra-high-energy cosmic rays in the Earth atmosphere. Since most of the air-shower energy flow is contained in the very forward region (where soft-QCD processes dominate), Monte Carlo simulations must rely on phenomenological...
Rare and radiative b-hadron decays are sensitive probes of New Physics through the study of branching fractions, angular observables, CP asymmetries and measurements of the polarisation of the photon emitted in the decay.
The LHCb experiment is ideally suited for the analysis of these decays due to its high trigger efficiency, as well as excellent tracking and particle identification...
The muon anomalous magnetic moment, $a_\mu=\frac{g-2}{2}$, is a low energy observable that can be both measured and computed with high precision. Therefore it provides an important test of the Standard Model (SM) and it is a sensitive probe for new physics. In particular, any deviation from the Standard Model theoretical value can be due to Beyond Standard Model Physics contribution, such as...
The project of the Super C-Tau factory (SCTF) is under development now at BINP in Novosibirsk. This electron-positron collider is intended for experiments in the energy range from 2 to 6 GeV with a luminosity of $10^{35}$ cm$^{-2}$s$^{-1}$. The high luminosity will provide a wide physical program that includes many fundamental issues like a study of mixing in the D meson system, search for...
Using Compton scattering of 0.5 \mum laser photons on existing 17.5 GeV (spent) electron beams from European XFEL one can obtain a gamma-gamma collider with W<12 GeV . This energy region is not covered by Super-B collider or LHC (the later due QCD backgrounds). Such a collider will be a nice place for application of modern technologies: powerful lasers, optical cavities, SC linacs and...
On the wake of the results obtained so far at the SPARC_LAB test-facility at LNF, we are currently investigating the possibility to design and build a new multi-disciplinary user-facility, equipped with a soft X-ray Free Electron Laser (FEL) driven by a ~1 GeV high brightness linac based on plasma accelerator modules. EuPRAXIA@SPARC_LAB is conceived as an innovative and evolutionary tool for...
I discuss the possibilities for using the LHC as a photon colliding
machine. The photon parton
density is quite precisely known and I consider the
implications for the LHC phenomenology. In addition, the colour singlet
nature of the photon means that it can readily lead to exclusive or
semi-exclusive events, with limited or no extra particle production in
the final state. I will show...
Understanding the properties of nuclear matter and its emergence through the underlying partonic structure and dynamics of quarks and gluons requires a new experimental facility in hadronic physics known as the Electron-Ion Collider (EIC). The EIC will address some of the most profound questions concerning the emergence of nuclear properties by precisely imaging gluons and quarks inside...
Since 2010 two detectors, CMD-3 and SND, have been collecting statistics at the electron-positron collider VEPP-2000. The collected integrated luminosity is about 200 pb$^{-1}$ for each detector in the wide c.m. energy range from 0.32 up to 2 GeV. The current status of analysis as well as recent results are reported. Special attention is paid to the studies of e^+e^- \to \pi^+\pi^-,...
