Conveners
Morning: Session 1
- Franco Bradamante (Universita e INFN Trieste (IT))
Morning: Session 2
- Harut Avakian
Morning: Session 1
- Patrizia Rossi (Jefferson Lab)
Morning: Session 2
- Anna Martin (Trieste University and INFN (IT))
Morning: Session 1
- Charlotte Van Hulse (University College Dublin (IE))
Morning: Session 2
- Gerhard Mallot (Albert Ludwigs Universitaet Freiburg (DE))
Morning: Session 1
- Alexey Vladimirov
Morning: Session 2
- Leonard Gamberg (Penn State University Berks)
Morning: Session 1
- Alexey Prokudin
Morning: Session 2
- Marco Contalbrigo (INFN - National Institute for Nuclear Physics)
I present the results of the extraction of unpolarized TMDs by the Pavia group. I describe the Pavia 2017 extraction, which included data from SIDIS and DY and performed the analysis at NLL, and the recent Pavia 2019 extraction, which included data from DY and reached N3LL accuracy. I will discuss the problems we encounter in the description of SIDIS data at higher accuracy.
The SIDIS data collected from 2002 to 2010 in COMPASS using a high energy muon beam and transversely polarised proton and deuteron targets, have allowed to performed many unique measurements. In this talk the main results and their interpretation, as well as the new expected measurements, will be reviewed. The need of the more deuteron data and the perspectives from the future COMPASS data...
In an effort to understand the internal structure of the nucleon, parton distributions describing longitudinal momentum, helicity and transversity distributions of quarks and gluons, have been generalized to account also for the transverse momentum of partons, providing important information on the spin-orbit correlations of partons in the nucleon. Transverse Momentum Dependent parton...
The partonic structure of the proton has been established in deep inelastic scattering and a detailed picture of the nucleon has emerged from a wide range of experiments and global analyses. Proton-proton collisions at RHIC allow direct access to the gluon content in the nucleon and polarized beams introduce an additional degree of freedom, spin, which is naturally connected to parton...
We derive and solve small-x evolution equations determining the small-x asymptotics of quark and gluon helicity PDFs and TMDs and orbital angular momentum (OAM) distributions. Our evolution equations resum powers of $\alpha_s \ln^2 (1/x)$. At large $N_c$, solving our equations, we obtain the following small-x asymptotics for helicity PDFs and OAM:
$\Delta \Sigma (x, Q^2) = - L_{q + \bar{q}}...
The hadron structure is commonly described by transverse momentum dependent (TMD) parton distribution functions (PDFs), which encode all possible correlations between the hadron spin, the parton spin and the transverse component of the parton momentum $k_\mathrm{T}$. They have been studied by COMPASS in semi-inclusive deep inelastic scattering (SIDIS) and DrellโYan (DY) reactions with...
Azimuthal correlations in the production of hadron pairs in semi-inclusive deep-inelastic scattering provide rich information on nucleon structure. The additional degree of freedom present in the two hadron final state allows for studies of correlations in the hadronization process, which can access novel fragmentation functions not accessible in single hadron production. Consequently, several...
The CLAS12 detector at Jefferson Laboratory (JLab) started data taking with a polarized 10.6 GeV electron beam, interacting with an unpolarized liquid hydrogen target in February 2018. The collected statistics enables a high precision study of the moment A$_{LU}^{sin(ฯ)}$ corresponding to the polarized electron beam spin asymmetry in semi-inclusive deep inelastic scattering. A$_{LU}^{sin(ฯ)}$...
A significant sample of $pp\to p\pi^{0}X$ events has been observed at STAR in
$\sqrt{s}=200$ GeV transversely polarized $pp$ collisions, with an isolated
$\pi^0$ detected in the forward pseudorapidity range $2.65<\eta<3.9$, along with
the forward-going proton $p$, which scatters near the beamline into Roman Pot
detectors. The sum of the $\pi^{0}$ and the scattered proton energies...
A very recent extention of a stand alone Monte Carlo simulation program of polarized quark fragmentation is presented. The initial program, implementing the recursive string+3P0 model, was restricted to the production of pseudoscalar mesons. The extension incorporates vector mesons, for the first time in accordance with quantum rules for spin.
The effects on observables like Collins and...
We are developing a unified approach that will include QED corrections to all of the structure functions of polarized SIDIS. In this talk, key features of SIDIS in one-photon approximation will be reviewed, and approaches to a consistent data analysis beyond the leading order in the electromagnetic interaction will be presented.
Selected topics related to the physics of the energy-momentum tensor (EMT) form factors are discussed.
In 2016 and 2017 exclusive reaction measurements were performed at the M2 beamline of the CERN SPS using 160 GeV positively and negatively charged muon beams scattering of a liquid hydrogen target. The Deeply Virtual Compton Scattering (DVCS) is the golden exclusive reaction to study Generalized Parton Distributions (GPDs). For this reaction, the scattered muons and the produced real photons...
The HERMES experiment has collected a wealth of deep-inelastic scattering data using the 27.6 GeV polarized electron or positron beams at HERA and various pure gas targets, both unpolarized and polarized. This allowed for a series of unique measurements. Among them are measurements in hard exclusive processes, such as deeply virtual Compton scattering process or exclusive meson production...
The 3-dimensional structure of the nucleon in QCD involves the specification of quark and gluon momenta and spin distributions. Generalized parton distributions (GPDs) encode the distributions in terms of fractional longitudinal and transverse momenta, spin helicity and transversity. The transversity transfer from the nucleon to its constituents in electroproduction is measured via chiral odd...
Despite decades of efforts in studying the internal structure of the nucleon, there are still a number of puzzles surrounding the proton such as its spin, mass, and the charge radius. The proton charge radius puzzle developed about ten years ago refers to a 5-7 ฯ discrepancy between the ultrahigh precise values of the proton charge radius determined from muonic hydrogen Lamb shift measurements...
With many attempts to experimentally constrain the leading-order term describing the non-pointlike nature of the proton, i.e. its mean-square charge radius, the overall situation is still ambigious and is a quest for new precision data.
COMPASS++/AMBER aims at contributing with a high-statistics measurement of high-energy muon-proton elastic scattering, complementing the respective campaign...
I will discuss issues related to transverse momentum dependent cross sections in
the limit that the transverse momentum is comparable to hard scales.
I will report on the application of the improved Collins-Soper-Sterman (iCSS) factorization formalism for the case of polarized observables, such as the Sivers effect in semi-inclusive deep-inelastic scattering. I will discuss how this study is being extended beyond leading order; this has direct impact on issues of relating/matching TMDs onto collinear twist-3 functions. I will briefly...
The basic ingredients of generation of single spin asymmetries are the formation
of pseudovetor, inerference of amplitudes and emergence of imaginary phase.
The latter, provided by final (initial) state interactions due to twist 3 effects or Sivers function in hadronic collisions, is suggested to correspond to the dissipation effects in heavy-ion collisions. Manifestation of the latter due...
The solution of the Bethe-Salpeter equation in Minkowski space resorting to an integral representation will be discussed for different systems composed by fermions and bosons. This framework provides results for the momentum distributions and electromagnetic form factor of a dynamical pion model [1] with constituent quarks exchanging an effective gluon inspired by lattice calculations of the...
All observed hadrons are color neutral, while they are all emerged from colored quarks and gluons (or partons) in high energy collisions. The COMPASS collaboration published precise data on production cross section of charged hadrons in lepton-hadron semi-inclusive deep inelastic scattering, showing almost an order of magnitude larger than next-to-leading order QCD calculations when hadrons...
From recent observations of W^{\pm} asymmetries and spin transfer to Lambda production in polarized proton and proton collisions at RHIC, we can obtain constraints on the polarization of ubar, dbar, s and sbar inside the proton. Theoretical predictions and perspectives are confronted with these experimental observations.
This talk provides an introduction to the conjecture The confinement mechanism for QCD involves a domain wall of topological (CP-odd) charge separating the interior volume of hadrons from an exterior volume The description is formulated in terms of the chiral structure of Yang-Mills-Maxwell equations for confined sources carrying color charge in the adjoint representation of SU(2) with...
The LHCspin project aims to bring both polarized and unpolarized physics at the LHC through the installation of a gaseous fixed target at the upstream end of the LHCb detector. The forward geometry of the LHCb spectrometer (2<ฮท<5) is perfectly suited for the reconstruction of particles produced in fixed-target collisions. The fixed-target configuration, with center-of-mass energies ranging...
The inclusive $J/\psi$ production is a powerful probe of the hadron structure. The process is sensitive to gluon and quark PDFs, has a large cross-section and clean experimental signal. At the same time, the interpretation of the experimental results is complicated due to the uncertainty of the $J/\psi$ production mechanism and by the presence of so-called feed-down contributions, i.e. decays...
We discuss $J/psi$ and $J/psi + jet$ production in electron-proton collision at the future EIC that can probe the poorly known gluon Sivers function.
Hadron structure and hadronization are flip sides of the โconfinement coin,โ yet hadronization has received much less attention in previous decades than hadron structure, in part due to its inherently dynamical nature. As we start to increase our focus on hadronization, new theoretical developments and experimental capabilities provide fertile territory for advances in our understanding. ...
I will discuss three central problems in QCD: (a) hadron dynamics and spectroscopy from light-front holography and superconformal algebra; (b) the behavior of the QCD running coupling in both the nonperturbative and perturbative domains; and (c) the elimination of perturbative QCD renormalization scale ambiguities. I will also review some highlights of my research in hadron physics over the...
