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# Correlations in Partonic and Hadronic Interactions - 2020 (CPHI-2020)

Europe/Zurich
774/R-013 (CERN)

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Description

The week-long workshop on Correlations in Partonic and Hadronic Interactions (CPHI-2020) will take place at CERN in Geneva, Switzerland, from February 3rd to 7th, 2020.
The workshop follows those held in 2018 and 2009 in Yerevan (Armenia).

Recently, significant disagreements have been reported in comparison of theoretical predictions, based on combination of TMD factorization and collinear factorization and experimental measurements for various transverse momentum distributions of hadrons in lepton-nucleon, electron-positron, and dileptons in DY process. Those observations emerge into a new crisis, the "qT -crisis". Correlations in partonic and hadronic interactions, which may be responsible for observed disagreements, provide important information on underlying dynamics, manifesting themselves in variety of observables widely recognized as key objectives of the forthcoming COMPASS (CERN) polarized deuteron run in 2021, JLab 12 GeV upgrade and a driving force behind construction of the Electron Ion Collider (BNL) and Spin Physics Detector (SPD) at the NICA facility (JINR).

The workshop will focus on the steps needed for development of theory and phenomenology involved in the extraction of TMDs and GPDs from existing and future data from lepton-nucleon, electron-positron and hadron-hadron facilities at BNL, CERN, DESY, FNAL, JINR, JLab, and KEK, with controlled systematics over various assumptions involved in the process.

Participants
• Albi Kerbizi
• Alessandro Bacchetta
• Alex Langnau
• Alexander Ilyichev
• Alexei Prokudin
• Alexey Guskov
• Anastasiia Afanaseva
• Andrea Moretti
• Andrea Simonelli
• Andrei Afanasev
• Andrei Gridin
• Andrew Chen
• Andrii Maltsev
• Anna Martin
• Anselm Vossen
• Ara Ioannisyan
• Aram Kotzinian
• Asmita Mukherjee
• Bakur Parsamyan
• Bo-Qiang Ma
• Bryan Joseph Ramson
• Charles-Joseph Naïm
• Charlotte Van Hulse
• Christian Dreisbach
• Christine Aidala
• Christopher Dilks
• Daniele Panzieri
• Dennis Sivers
• Eckhard Elsen
• Eli Piasetzky
• Eva-Maria Kabuss
• Fabienne Kunne
• Fulvio Tessarotto
• Gary Goldstein
• Gerhard Mallot
• Gunar Schnell
• Guy de Teramond
• Haiyan Gao
• Harut Avagyan
• Hrachya Marukyan
• Hrayr Matevosyan
• Igor Denisenko
• Jan Friedrich
• Jan Matousek
• Jean-Philippe Lansberg
• Jianwei Qiu
• Johannes Vincenzo Giarra
• Judith Brodsky
• Julia Panteleeva
• Kawtar Hafidi
• Kirill Semenov-Tyan-Shansky
• Leonard Gamberg
• Marc Schlegel
• Marcia Quaresma
• Marco Contalbrigo
• Markus Diehl
• Marta Ruspa
• Matthias Burkardt
• Maxim Alexeev
• Maxim Nefedov
• Maxim Polyakov
• Michael Wood
• Mikhail Mikhasenko
• Misak Sargsian
• Nicole D'Hose
• Oleg Eyser
• Oleg Teryaev
• Olena Afanaseva
• Olga Kubarovskaia
• Or Hen
• Pasquale Di Nezza
• Patrizia Rossi
• Paul Hoyer
• Piet Mulders
• Ralf Seidl
• Riccardo Longo
• Robert McKeown
• Sergei Gerassimov
• Sergey Gevorkyan
• Simonetta Liuti
• Stanley Brodsky
• Stefan Diehl
• Stefano Levorato
• Stephane Platchkov
• Susan Gardner
• Ted Rogers
• Timothy Hayward
• Tobias Frederico
• Valery Kubarovsky
• Vincent Andrieux
• Yann Bedfer
• Yuri Kovchegov
• ZEIN-EDDINE MEZIANI
Webcast
There is a live webcast for this event
Contact/Support
• Monday, February 3
• 8:30 AM
Registration 774/R-013

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• Morning: Session 1 774/R-013

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Convener: Franco Bradamante (Universita e INFN Trieste (IT))
• 1
Welcome
Speaker: Eckhard Elsen (CERN)
• 2
Extraction of unpolarized TMDs: successes and problems

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.

Speaker: Prof. Alessandro Bacchetta (University of Pavia)
• 3
The transverse spin structure of the nucleon: overview and perspectives of COMPASS SIDIS measurements

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 taking will also be summarised.

Speaker: Anna Martin (Trieste University and INFN (IT))
• 4
The Jefferson Lab TMD Studies at 12 GeV

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 distributions (TMDs) yields a 3D picture of the nucleon in momentum space and can be accessed in semi-inclusive processes.
The recently upgraded Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab (JLab) provides a unique opportunity to study the quark TMDs, particularly in the valence quark region, and a coherent and comprehensive TMD program using SIDIS measurements is underway. The program takes advantages of the complementary capabilities of different detectors in the experimental Halls A, B and C.
In this talk we present an overview of the latest developments in studies of TMDs at JLab and discuss newly released results, ongoing activities, as well as planned near term and future measurements.

Speaker: Patrizia Rossi (Jefferson Lab / INFN-LNF)
• 5
Recent Results from RHIC: Cold QCD & Spin

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 kinematics. Transverse spin phenomena are enabling studies of transverse momentum dependent distribution functions and spin-orbit correlations beyond a one-dimensional picture. At the same time, they are closely linked to questions about universality of the process dependence of color exchanges, factorization, and possibly saturation effects a very small partonic momenta.

Speaker: Dr Oleg Eyser (Brookhaven National Laboratory)
• 11:00 AM
Coffee break 774/R-013

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• Morning: Session 2 774/R-013

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Convener: Harut Avakian
• 6
Helicity Distributions and OAM at Small x

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:
$\Delta \Sigma (x, Q^2) = - L_{q + \bar{q}} (x, Q^2) \sim \left(\frac{1}{x}\right)^{\frac{4}{\sqrt{3}} \, \sqrt{\frac{\alpha_s \, N_c}{2 \pi}} }$ ,
$\Delta G (x, Q^2) \sim L_G (x, Q^2) \sim \left(\frac{1}{x}\right)^{\frac{13}{4 \sqrt{3}} \, \sqrt{\frac{\alpha_s \, N_c}{2 \pi}}}$.

Speaker: Prof. Yuri Kovchegov (The Ohio State University)
• 7
The origin of single transverse-spin asymmetries in high-energy collisions

We present, for the first time, a phenomenological
analysis that demonstrates all single transverse-spin asymmetries (SSAs) in
high-energy collisions have a common origin.
Namely, they are due to the intrinsic quantum-mechanical interference
between single- and multi-parton states.
We perform the first global fit of data from Semi-Inclusive Deep
Inelastic Scattering, Drell-Yan, $e^+e^-$ annihilation into hadron
pairs, and proton-proton collisions.
Consequently, we are able to identify a unique set of
functions that describes all observed SSAs.
Furthermore, we achieve the first phenomenological agreement with
lattice on the tensor charge of the nucleon.

Speaker: Alexey Prokudin
• 8
Recent HERMES results on polarized semi-inclusive deep-inelastic scattering

After fifty years of investigations, the nucleon structure is still far from being understood and continues to represent a unique test bench for QCD. Despite the enormous progresses achieved in five decades of deep-inelastic scattering (DIS) experiments, a number of crucial open questions are still on the carpet and subject of intense theoretical and experimental studies. In the last two decades, semi-inclusive DIS was established as a unique tool for the study of the non-collinear structure of nucleons, involving the parton transverse momentum pT as an additional degree of freedom. Requiring the detection of at least one final state hadron in coincidence with the scattered lepton, it opened the way not only to the measure of the chiral-odd transversity distribution, the last missing leading-twist collinear parton distribution function, but also to a variety of new pT-dependent PDFs, known as TMDs. Describing correlations between the quark transverse momentum and the quark or the nucleon spin (spin-orbit correlations), TMDs account for a number of intriguing effects observed in polarized and unpolarized reactions, and allow for a 3-dimensional description of the nucleon in momentum space (nucleon tomography). Furthermore, they could provide insights into the yet unmeasured quark orbital angular momentum. At leading-twist eight TMDs enter the SIDIS cross section in conjunction with a fragmentation function. In addition, going to the twist-3 level allows us to probe novel quark-gluon correlations. At HERMES, these distribution functions are probed through specific azimuthal modulations in the distribution of hadrons produced in semi-inclusive DIS of unpolarized or longitudinally polarized electrons and positrons off unpolarized and polarized nucleons. Amplitudes of some of these modulations sensitive to the beam polarization, recently extracted also in a three-dimensional kinematic space, will be presented in more detail.

Speaker: Gunar Schnell
• 12:35 PM
Lunch 866, Restaurant 3

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• Afternoon: Session 3 774/R-013

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Convener: Alessandro Bacchetta (University of Pavia)
• 9
Extraction of Sivers and Transversity: access to the exotics of polarized parton densities

The Sivers and Transversity distributions represent the prototype of naive T-odd and chiral-odd parton densities, respectively. Having a good knowledge of the former allows to test the QCD prediction of specific non-universality, while the first Mellin moment of the latter, the so-called tensor charge, might represent a possible portal to new physics beyond the Standard Model. I will present the latest extraction of the Sivers function, for the first time starting from the extracted unpolarized TMD distribution in a consistent TMD framework. I will also discuss the latest results for Transversity from a global analysis of pion-pair production in deep-inelastic scattering and in proton-proton collisions, with particular emphasis on the comparison with recent lattice calculations of the valence and isovector components of the tensor charge.

Speaker: Dr Marco Radici (INFN)
• 10
Description of unpolarized DY and SIDIS data within TMD factorization

I present the analysis of the semi-inclusive deep inelastic scattering (SIDIS) and Drell-Yan events within transverse momentum dependent (TMD) factorization. The high quality of the fit confirms a complete universality of TMD non-perturbative distributions and demonstrates good agreement between the theory and the data. Also, I provide the discussion on phenomenological analyses of various parts of the TMD factorization, such as sensitivity to non-perturbative parameterizations, perturbative orders, collinear distributions, correlations between parameters, and others.

• 11
Accessing TMDs with an unpolarised target at HERMES

The HERMES experiment collected from 1995 to 2007 a wealth of deep-inelastic scattering data using 27.6 GeV longitudinally polarised electrons and positrons and various unpolarised as well as longitudinally and transversely polarised gas targets. This allowed for a series of diverse measurements. Among them are measurements in semi-inclusive deep-inelastic scattering that provide information on various transverse-momentum-dependent parton distribution functions and fragmentation functions. Related results from HERMES using an unpolarised nucleon and a longitudinally and effectively unpolarised lepton beam are presented and discussed.

Speaker: Charlotte Van Hulse (University College Dublin (IE))
• 12
TMD observables in unpolarised SIDIS at COMPASS

In 2016 and 2017 the COMPASS Collaboration at CERN collected a large sample of DIS events with a longitudinally polarized 160 GeV/$c$ muon beam scattering off a liquid hydrogen target. A small subsample of the collected data has been analysed to extract preliminary results for the transverse momentum dependent charged hadron multiplicities and the amplitudes of the azimuthal modulations $A_{UU}^{\cos\phi_h}$, $A_{UU}^{\cos 2\phi_h}$ and $A_{LU}^{\sin \phi_h}$. Both multiplicities and azimuthal asymmetries can be related to the intrinsic transverse momentum $k_{T}$ of the quarks, while $A_{UU}^{\cos\phi_h}$ and $A_{UU}^{\cos 2\phi_h}$ are also related to the still unknown Boer-Mulders TMD PDF $h_{1}^{\perp}$. In this talk, preliminary results from the 2016 data will be shown for both observables. It is found that the unpolarised azimuthal asymmetries exhibit strong kinematic dependences, which are similar to the published COMPASS deuteron results. Recently, it has been demonstrated that particles coming from the decay of diffractively produced vector mesons contribute considerably to these observables. The planned strategy for the 2016/17 data analysis will be discussed.

Speaker: Andrea Moretti (Universita e INFN Trieste (IT))
• 3:40 PM
Coffee break 774/R-013

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• Afternoon: Session 4 774/R-013

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Convener: Gunar Schnell
• 13
COMPASS results on pion and kaon multiplicities in DIS and ratios of K-/K+ and pbar/p multiplicities.

We present preliminary COMPASS results on pion and kaon multiplicities produced in semi-inclusive deep inelastic scattering of 160 GeV muons off a pure proton (LH2) target. The results constitute a data set of more than 600 points for pions and 600 for kaons, covering a large x, Q2 and z domain in a fine binning with W>5 GeV2. The results from the sum of the z-integrated multiplicities M(π+) + M(π-) and M(K+) + M(K-) are presented versus x and compared to earlier COMPASS results on a deuteron target and to other experiments.

In addition, we show the K-/K+ as well as pbar/p multiplicity ratios measured for hadrons carrying a large fraction z of the virtual-photon energy, 0.5 < z <1, using an isoscalar 6LiD target. The ratios can be obtained with lower systematic errors. For values of z larger than 0.8, the results contradict expectations obtained using the formalism of (next-to-) leading order perturbative quantum chromodynamics. In particular the data show a strong dependence upon the missing mass Mx, not expected from the calculations. The results suggest that additional corrections to the formalism may be required to take into account the phase space available for hadronization.

Speaker: Fabienne Kunne (Université Paris-Saclay (FR))
• 14
unpolarized fragmentation related measurements at Belle

The fragmentation process can be cleanly studied at electron-positron colliders where no hadrons exist in the initial state. The Belle experiment at the KEK-B collider has accumulated more than one inverse ab of data. This large amount of data has been used to measure various fragmentation related quantities such as single and di-hadron cross sections for several hadron types.
In this presentation the unpolarized measurements will be discussed, in particular the transverse momentum dependent single hadron cross sections as well as updates to fractional momentum dependent single and di-hadron cross sections.

Speaker: Ralf Seidl (RIKEN)
• 15
Hadronization with polarization degrees of freedom

Considering polarization degrees of freedom in the final state of hard, semi-inclusive interactions allows a more focused access to the partonic structure of the nucleon. The respective fragmentation functions can be used to study QCD in the non-perturbative regime complementary to polarized (TMD) PDFs.
This talk will discuss recent and anticipated results on polarized fragmentation functions in e+e- and SIDIS.

Speaker: Anselm Vossen (Duke University)
• 16
Universality-breaking effects in e+e- hadroproduction

Recent BELLE measurements provide the cross section for single hadron production in e+e- annihilations, differential in the hadron transverse momentum with respect to the thrust axis. Universality breaking effects due to process-dependent soft factors make it very difficult to relate this cross section to that corresponding to hadron-pair production in e+e- annihilations, where TMD fragmentation functions are defined through the so-called "square-root definition". I will examine this correspondence in the framework of CSS factorization and provide the sketch of a scheme that might allow to relate 1-jet to 2-jet e+e- cross sections, neatly separating soft and collinear non-perturbative effects from the terms which can be calculated using a perturbative approach.

Speaker: Andrea Simonelli (University of Torino and INFN Torino)
• 6:30 PM
Welcome drink Restraurant Le Casanova

#### Restraurant Le Casanova

• Tuesday, February 4
• Morning: Session 1 774/R-013

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Convener: Patrizia Rossi (Jefferson Lab)
• 17
Transverse momentum weighted transverse spin asymmetries at COMPASS

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 Drell–Yan (DY) reactions with transversely polarised proton targets by measuring the transverse spin asymmetries (TSAs). The TSAs in SIDIS contain convolutions over the transverse momentum of TMD PDFs and TMD fragmentation functions (FFs). Similarly, the TSAs in DY are interpreted as convolutions of the TMD PDFs of the target and beam hadrons. To extract the TMD PDFs, an ansatz for their dependence on $k_\mathrm{T}^2$ is needed. Different observables – the transverse momentum weighted TSAs – were proposed a long time ago. Instead of convolutions, they contain products of various $k_\mathrm{T}^2$-moments of the TMD PDFs and FFs. To measure the weighted TSAs, one needs to weight the events with correct powers of the transverse momentum of the final state hadron in SIDIS or of the dimuon in DY. COMPASS has recently measured the weighted TSAs in both SIDIS and DY to complement its results on the standard TSAs. Thanks to their straightforward interpretation, the Sivers functions measured in SIDIS and DY can be directly compared. Additionally, COMPASS also obtains information on the pion valence Boer–Mulders function, the correlation of the parton transverse spin and its $k_\mathrm{T}$.

Speaker: Jan Matousek (Universita e INFN Trieste (IT))
• 18
Dihadron beam-spin asymmetries at CLAS12

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 PDFs such as the higher-twist collinear PDF $e(x)$ or the as yet unmeasured dihadron fragmentation function $G_1^{\perp}$ can be extracted. We present preliminary charged pion beam-spin asymmetries from a subset of the data taken in 2018 with the CLAS12 detector at Jefferson Lab. The data were taken with a 10.6 GeV polarized electron beam and an unpolarized liquid-hydrogen target. The large kinematic acceptance and sample size allows for a multidimensional analysis in Bjorken $x$, $z$ and the invariant mass of the hadron pair.

Speaker: Timothy Hayward (The College of William and Mary)
• 19
SIDIS Single Pion Beam Spin Asymmetry measurements with CLAS 12

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$_{LU}^{sin(ϕ)}$ corresponding to the polarized electron beam spin asymmetry in semi-inclusive deep inelastic scattering. A$_{LU}^{sin(ϕ)}$ is a twist-3 quantity which provides information about the quark gluon correlations in the nucleon. The contribution will present a simultaneous study of all three pion channels (π$^+$, π$^0$ and π$^−$) over a large kinematic range of z, x$_B$, P$_T$ and Q² with virtualities Q² ranging from 1 GeV² up to 8 GeV². Based on the available statistics, a multidimensional analysis becomes possible.

Speaker: Dr Stefan Diehl (JLU Giessen and UCONN)
• 20
Transverse Single Spin Asymmetries in the $pp \to p\pi^{0}X$ Process at STAR

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 is
consistent with the incident proton energy of 100 GeV, indicating that no
further particles are produced in this direction. It is postulated that the
forward incident proton may have fluctuated into a $p+\pi^{0}$ system, with the
$\pi^0$ angular momentum correlated with the initial proton spin. The
$p+\pi^{0}$ system scatters off the other beam proton and separates such that
the $\pi^{0}$ has a transverse momentum of ${\sim}2$ GeV/$c$ and the proton has
a transverse momentum of ${\sim}0.2$ GeV/$c$. The other beam proton shatters
into the remnant particles $X$, all in the backward direction. Correlations
between the $\pi^0$ and scattered proton will be presented, along with single
spin asymmetries which depend on the azimuthal angles of both the pion and the
proton. This is the first time that spin asymmetries have been explored for
this process, and a model to explain their azimuthal dependence is needed.

Speaker: Christopher Dilks (Duke University)
• 10:40 AM
Coffee break 774/R-013

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• Morning: Session 2 774/R-013

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Convener: Anna Martin (Trieste University and INFN (IT))
• 21
Inclusion of vector meson production in the Monte Carlo simulation of polarized quark fragmentation

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 di-hadron transverse spin asymmetries are shown.

Speaker: Albi Kerbizi (Universita e INFN Trieste (IT))
• 22
Two-Photon-Exchange Corrections to SIDIS

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.

Speaker: Prof. Andrei Afanasev (George Washington University)
• 23
Radiative corrections in polarized SIDIS

The important sources of the systematical uncertainties in polarized SIDIS experiments are the QED radiative corrections (RC). Here the model-independent RC that include the effects of real photon radiation and loop diagrams (leptonic vertex correction, and vacuum polarization) are presented. The effects were analytically computed within the Bardin-Shumeiko approach resulting in explicit equations in leading and next-to-leading orders. The numeric estimation of the correction due to the real photon radiation requires the integration over wide kinematical region of the unobservable real photon emission from the lepton leg withing SIDIS and exclusive final state and therefore requires knowledge of all 5 spin-averaged and 13 spin-dependent structure functions (SFs) in these region. In our illustrations for JLAB kinematics we used the WW-SIDIS model and a simple approach for exclusive SFs. The ways to address limitations of our calculations due to limited knowledge of all exclusive SFs are discussed.

Speaker: Alexander Ilyichev
• 12:25 PM
Lunch 866, Restaurant 3

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• Afternoon: Session 3 774/R-013

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Convener: Fulvio Tessarotto (Universita e INFN Trieste (IT))
• 24
Probing nucleon’s structures using Drell-Yan process with unpolarized/polarized targets at Fermilab

The mysterious asymmetry of the anti-quarks inside nucleon remains to be investigated. The experiment SeaQuest, with unpolarized targets, aims to do so. The experiment finished data collection in 2017. A preliminary result will be given in this presentation. The spin structure of the nucleon remains a mystery. Recent studies suggest that the orbital angular momentum of sea quarks could significantly contribute to the proton’s spin. The SpinQuest will access the anti-quark Sivers functions using polarized NH3 and ND3 targets. A non-zero asymmetry, observed in SpinQuest, would be a strong indication of non-zero sea-quark orbital angular momentum. The SpinQuest can also probe the sea quark’s transversity as well as the tensor charge of polarized ND3. The status of the SpinQuest preparation will be presented.

Speaker: Dr Andrew (aka Yen-Chu) Chen (UIUC)
• 25
Drell-Yan measurements at COMPASS

COMPASS is a fixed-target experiment in operation at the CERN North Area (SPS, M2 beam-line) since 2002. An important part of the broad physics programme of the experiment is dedicated to the exploration of the transverse spin-structure of the nucleon, studying target transverse spin (in)dependent azimuthal asymmetries arising in the Drell-Yan cross-section.

In 2015 and 2018, COMPASS performed two years of Drell-Yan data taking, using a 190 GeV/$c$ $\pi^-$ beam impinging on a transversely polarized NH$_3$ target.
In this talk, recent Drell-Yan results from COMPASS will be presented along with prospects for ongoing studies.

Speaker: Riccardo Longo (Univ. Illinois at Urbana Champaign (US))
• 26
Power corrections at moderate qT from Reggeized Partons

Power-supressed O(qT^2/Q^2) corrections to the Drell-Yan TMD cross-sections and structure functions, which restore QED gauge-invariance of the hadronic tensor in TMD factorization will be discussed in a framework of Parton Reggeization Approach [1,2]. These corrections are important in the region of moderate qT~Q for the description of qT-spectrum and Helicity Structure Functions, and are not taken into account in the standard (Collinear Factorization based) construction of a Y-term. Therefore these corrections could potentially contribute to the resolution of qT-puzzle in Drell-Yan and SDIS.

[1] M.~Nefedov and V.~Saleev,
Off-shell initial state effects, gauge invariance and angular distributions in the Drell–Yan process,''
Phys. Lett. B 790, 551 (2019)
doi:10.1016/j.physletb.2018.12.071
[arXiv:1810.04061 [hep-ph]].

[2] M.Nefedov and V.Saleev,
Off-shell initial state effects and gauge invariance in the Drell-Yan process,''
PoS DIS 2019, 193 (2019)
doi:10.22323/1.352.0193
[arXiv:1906.08681 [hep-ph]].

Speaker: Vladimir Saleev (Samara National Research University)
• 27
Measurement of pion induced Drell-Yan at AMBER experiment

AMBER is a newly proposed experiment at CERN with the aim of contributing in the field of QCD. Among several ideas, the measurement of the pion induced Drell-Yan with the two pion charges is one of the proposed measurements. The combination of the two pion charges together with a carbon target gives access to observables sensitive to the separation between sea and valence in the pion. In addition, with the inclusion of a W target, studies on the nuclear effects are also possible with the particularity of studying their flavour dependence. The scientific proposal for this measurement is currently being evaluated by SPS Committee and should be soon presented to the CERN Council. In a later stage, the plan is to measure the kaon induced Drell-Yan. A precise knowledge of the pion and kaon structures, together with the proton, lead us to the possibility of better understanding the origin of the hadrons masses. In this talk the proposed measurement will be introduced and some projections will be showed.

Speaker: Marcia Quaresma (LIP Laboratorio de Instrumentacao e Fisica Experimental de Part)
• 3:40 PM
Coffee break 774/R-013

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• AKM-70 774/R-013

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Convener: Bakur Parsamyan (CERN, University of Turin and INFN)
• 28
Aram’s no-nonsense TMD’s
Speaker: Piet Mulders (VU/Nikhef)
• 29
SSAs in Electroproduction

The quark-gluon dynamics manifests itself in a set of non-perturbative functions describing various spin-spin and spin-orbit correlations. Single and Dihadron semi-inclusive production, both in current and target fragmentation regions, provide a variety of spin and azimuthal angle dependent observables. In this talk, we present several measurements of Spin-Azimuthal Asymmetries sensitive to the orbital structure, and in particular, the Kotzinian-Mulders asymmetry.

Speaker: Dr Harut Avakian
• 30
Physics at the back of an envelope

I will tell a few (pseudo)scientific anecdotes of my 15+ year old friendship and scientific collaboration with Aram Kotzinian dedicated to his 70th Birthday.

Speaker: Alexey Prokudin
• 31
Exploring the spin effects in dihadrons with Aram

In this talk I will present some highlights from the work we have done in collaboration with Aram Kotzinian on exploring spin-induced dihadron correlations in quark hadronization process, and the measurements we proposed for accessing the quark-polarization-dependent dihadron fragmentation functions in $e^+e^-$ and SIDIS experiments.

Speaker: Dr Hrayr Matevosyan (University of Adelaide)
• 32
Nucleon-spin-dependent azimuthal asymmetries and beyond: AKM 55-70

Measurements of the nucleon spin (in)dependent azimuthal asymmetries in semi-inclusive DIS are one of the most important sources of information about transverse momentum dependent parton distribution and fragmentation functions.
Aram Kotzinian is one of the pioneers of this field.

Speaker: Bakur Parsamyan (CERN, University of Turin and INFN)
• 6:30 PM
AKM-70 celebration 500, Restaurant 1, "Glass Box"

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• Wednesday, February 5
• Morning: Session 1 774/R-013

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Convener: Charlotte Van Hulse (University College Dublin (IE))
• 33
Mechanical properties of particles

Selected topics related to the physics of the energy-momentum tensor (EMT) form factors are discussed.

Speaker: Maxim V. Polyakov
• 34
overview of the COMPASS GPD program

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 were detected by the COMPASS spectrometer, which was supplemented by an additional electromagnetic calorimeter for the detection of large-angle photons. To insure the exclusivity of the reaction, the recoil protons were detected by the CAMERA detector, which measures the time of flight between two barrels of scintillators surrounding the 2.5 m long target. We will summarize the status of the analysis of the data and present results from the one-month 2012 pilot run which represents about one tenth of the total statistics collected in 2016-17.

By summing up the DVCS cross sections when using either a positive or a negative muon beam the total DVCS cross section and its |t|-dependence can be extracted. From this measurement mainly related to the GPD H, a first estimate of the transverse extension of partons in the proton probed in the sea-quark domain is determined. We will also report on the cross section for exclusive pi0 production and its |t| and azimuthal dependence as well as on the spin density matrix elements for exclusive omega meson production. These measurements are aiming to constrain GPDs, in particular the chiral-odd (transversity) GPDs H_T and Ē_T.

Speaker: Dr Nicole d'Hose (CEA - Université Paris-Saclay)
• 35
Challenges in Nuclear Femtography
Speaker: latifa Elouadrhiri (Jefferson Lab)
• 36
Study of GPDs at HERMES

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 processes. They provide information on the three-dimensional structure of the nucleon both in momentum space and in mixed momentum and position space. Results on various cross-section asymmetries, sensitive to generalized parton distributions and thus to the three-dimensional nucleon structure in mixed momentum and position space, are shown. The operation of a recoil detector during the last two years of HERMES running enabled for the full kinematic reconstruction of the events of exclusively produced real photons and a clean (with a background well below the 1%) measurement of the beam-helicity asymmetry. Also, first measurement of the beam helicity asymmetry related to the associated deeply virtual Compton scattering process, where the proton is excited to a Δ-resonance state, was possible using the recoil detector information. Spin density matrix elements and transverse-target spin asymmetries in exclusive meson production on unpolarized protons and deuterons and on transversely polarized protons, respectively, as well as helicity amplitude ratios from exclusive rho production on transversely polarized protons are presented as well.

Speaker: Prof. Hrachya Marukyan (A.Alikhanyan National Science Laboratory (Yerevan Physics Institute))
• 10:40 AM
Coffee break 774/R-013

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• Morning: Session 2 774/R-013

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Convener: Gerhard Mallot (Albert Ludwigs Universitaet Freiburg (DE))
• 37
Chiral Odd GPDs

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 interactions between the beam and the partons, the transversity GPDs. These are most directly determined in cross sections and asymmetries for exclusive electroproduction of pseudoscalar mesons, particularly pions and eta mesons. Predictions from a successful "Flexible Model" for these GPDs will be presented and compared with some of the extensive data on meson electroproduction.

Speaker: Gary Goldstein (Tufts University)
• 38
Studies of Transversity GPDs

A longstanding goal in nuclear and particle physics has been to describe the three-dimensional structure of the nucleon in terms of the quarks and gluon fields. In this regard, exclusive electron scattering experiments, in which all final state particles are measured, are important contributors. Examples are electron elastic scattering, deeply virtual Compton scattering (DVCS), and deeply virtual meson electroproduction (DVMP). The latter includes pseudoscalar mesons with intrinsic spin and parity $J^P=0^-$, such as $\pi^0$, $\pi^-$, $\pi^+$ and $\eta$, and vector mesons, which have the same spin and parity as the photon, $J^P=1^-$, such as $\rho^-$, $\rho^+$, $\rho^-$, $\omega$ and $\phi$. Exclusive electron scattering reactions at high momentum transfers directly related to Generalized Parton Distributions (GPDs) of quarks and gluons. Most reactions studied, such as DVCS or vector meson electroproduction, are primarily sensitive to the chiral-even GPDs. Very little is known about the chiral-odd GPDs, which are difficult to access since hard subprocesses with the quark spin-flip are suppressed. It turns out that pseudoscalar meson electroproduction, and especially $\pi^0$ and $\eta$ production, were identified as especially sensitive to the parton helicity-flip subprocesses.
Dedicated experiments to study Deeply Virtual Meson Production out of proton and neutron have been carried out at Jefferson Lab. The cross sections and asymmetries of the exclusive pseudoscalar meson electroproduction processes in a very wide kinematic range of $Q^2$, $x_B$ and $t$ have been measured with CLAS. The comparison of these data with the theoretical models will be presented. The extraction of the transversity GPDs parameters using global fit of the available data will be discussed in the report.

Speaker: Valery Kubarovsky
• 39
The proton charge radius from the PRad experiment

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 σ discrepancy between the ultrahigh precise values of the proton charge radius determined from muonic hydrogen Lamb shift measurements and the CODATA values compiled from electron-proton scattering experiments and hydrogen spectroscopy measurements. In this talk, I will introduce the proton charge radius puzzle and then focus on the PRad experiment at Jefferson Lab and its result.

Speaker: Prof. Haiyan Gao (Duke University)
• 40
Proton radius with COMPASS++/AMBER

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 with low-energy muons at MUSE/PSI. Data taking is proposed from 2022 on.

Speaker: Jan Friedrich (Technische Universitaet Muenchen (DE))
• 12:40 PM
Lunch 866, Restaurant 3

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• Afternoon: Session 3 774/R-013

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Convener: Jan Friedrich (Technische Universitaet Muenchen (DE))
• 41
Prompt photon production in the $k_T$-factorization: parton Reggeization approach}

Parton Reggeization approach (PRA) is based on $k_T$-factorization of hard processes at multi-Regge kinematics. In PRA, initial state partons are treated as Reggeized gluons and Reggeized quarks, which are quantum fields of Lipatov's Effective Theory [1]. This one guarantees gauge invariance for off-shell hard amplitudes. As it was shown in [2], unintegrated (transverse momentum dependent) parton distribution functions (uPDFs) of off-shell partons $\Phi(x,{\bf q}_T^2,\mu^2)$ is naturally described by the Kimber-Martin-Ryskin (KMR) model [3].

Inclusive production of isolated photon is described in the leading order (LO) of PRA via $2\to 1$ parton subprocess $Q\bar Q\to \gamma$. The gauge invariant amplitude of this process is proportional to Fadin-Sherman effective vertex $\Gamma_{QQ\gamma}^\mu$ [4].

At first, we study single photon production in LO PRA in $pp(p\bar p)$ collisions at the energies of LHC and Tevatron Colliders using original KMR model for uPDFs. To study processes at sufficiently low energies (from $\sqrt{S}=20$ to $\sqrt{S}=200$ GeV), we suggest modified multi-Regge approximation in which modified KMR model can be used at arbitrary $x$. We describe old data from SPS, RHIC and predict photon spectra for future SPD NICA experiment.

We have studied photon production in LO and NLO PRA in Refs. [5]-[8].

[1] L.N. Lipatov L.N. Gauge invariant effective action for
high energy processes in QCD. Nucl. Phys. {\bf B452} (1995) 369;
L.N. Lipatov, M.I. Vyazovsky. Quasi-multi-Regge processes with a
quark exchange in the t-channel, Nucl. Phys. {\bf B597} (2001) 399.

[2] A.V. Karpishkov, M.A. Nefedov and V.A. Saleev,
$B{\bar B}$ angular correlations at the LHC in parton Reggeization approach merged with higher-order matrix elements, Phys. Rev. D 96 (2017) no.9, 096019.

[3] M. A. Kimber, A. D. Martin, and M. G. Ryskin, Unintegrated
parton distributions and prompt photon hadroproduction, Eur. Phys.
J. C12 (2000) 655.

[4] V. Fadin V and V. Sherman, Fermion reggeization in nonabelian
calibration theories, JETP Lett. 23 (1976) 599.

[5] M. Nefedov and V. Saleev, Diphoton production at the Tevatron and the LHC in the NLO approximation of the parton Reggeization approach, Phys. Rev. D92 (2015) no.9, 094033

[6] B.A. Kniehl, M.A. Nefedov and V.A. Saleev, Prompt-photon plus jet associated photoproduction at HERA in the parton Reggeization approach
Phys. Rev. D89 (2014) no.11, 114016

[7] B.A. Kniehl, V.A. Saleev, A.V. Shipilova and E.V. Yatsenko,
Single jet and prompt-photon inclusive production with multi-Regge kinematics: From Tevatron to LHC, Phys. Rev. D {\bf 84} (2011) 074017

[8] V.A. Saleev, Prompt photon photoproduction at HERA within the
framework of the quark Reggeization hypothesis, Phys. Rev. D78 (2008) 114031.

Speaker: Prof. Vladimir Saleev (Samara National Research University)
• 42
Gluon structure of hadrons with prompt photons at COMPASS-AMBER and NICA-SPD.

Prompt photon production in hadronic collisions is a proven way to access unpolarised and polarised gluon structure of hadrons. Possible physics with prompt photons at the COMPASS-AMBER experiment at CERN and at the SPD experiment at the NICA collider at JINR (Dubna, Russia) will be presented.

Speaker: Dr Alexey Guskov (Joint Institute for Nuclear Research (RU))
• 43
The transverse single spin asymmetry in photon SIDIS

The transverse single spin asymmetry of a nucleon is discussed for the semi-inclusive production of photons in lepton-nucleon collisions. Arguments are given that this particular observable is very suitable to study quark-gluon correlation functions in the nucleon. Experimental data, for example taken at a future Electron-Ion Collider, on this observable may help to constrain these correlation functions. In this way one can gain more insight into the origin of transverse single spin asymmetries.

Speaker: Marc Schlegel (New Mexico State University)
• 44
Has vector meson polarization the impact on its interaction with matter?

Light vector mesons $V=\rho,\omega,\varphi, K^*$ etc. can be transversely (helicity $\lambda=\pm 1$) or longitudinally ($\lambda=0$ ) polarized.\
Has their polarization impact on their interaction with nucleons and nuclei?\
The unstable meson total cross section with nucleon can be extracted by measuring the absorption of mesons in the production off nuclei as
the nuclear absorption depends on the meson-nucleon total cross section and consequently on the vector meson polarization.\
Whereas the meson coherent photoproduction off nuclei allows to determine the transverse total cross section $\sigma_T(VN)$ the incoherent production can be a good tool
to extract the information on the value of the total cross section of longitudinally polarized vector meson with nucleon $\sigma_L(VN)$. In the talk we discuss the importance of a knowledge
of this cross sections and possibility to determine these quantities from $\omega$ mesons photoproduction at JLAB and charge exchange reaction on a set of nuclei $\pi^-A\to VA'$ using the
COMPASS++/AMBER facility at SPS,CERN.

Speaker: Dr Sergey Gevorkyan (JINR)
• 3:40 PM
Coffee break 774/R-013

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• Afternoon: Session 4 774/R-013

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Convener: Harut Avakian
• 45
New Results on PDFs in Nucleons and Nuclei

We report an observation of new properties of valence quark partonic
distribution that allows to derive new relations that can be used to constrain
phenomenological parameterizations of PDFs. These relations allow
to formulate a “mean field theorem” according to which no fixed number
constituent exchanges can be responsible for the valence quark distributions
in 0.1 < x < 0.3 region. This in turn explains why no nuclear medium
modification is observed for partonic distribution in this regio

Speaker: Misak Sargsian (Florida International University)
• 46
Present and Future Studies of Color Transparency and Hadronization in Hall B

For a complete description of the strong interaction, Quantum Chromodynamics (QCD) must be able to predict the dynamics of the free quarks in the nuclear medium. Put another way, the nucleus is a good laboratory to study the propagation of free quarks and the formation of color-neutral objects. This talk will describe a program at Hall B at the Thomas Jefferson National Accelerator Facility (JLab) to study Color Transparency and Hadronization. Color Transparency is the process of the cancellation of QCD color fields for small singlet system of quarks and gluons and predicts a vanishing of the final state interactions of hadrons with the nuclear medium in exclusive processes at high momentum transfers. Hadronization is the process of forming hadrons out of quarks and gluons, and using various nuclei allows for studies of the propagation time and the formation time. Existing data from CLAS6 and future experiments with CLAS12 will be presented.

Speaker: Dr Michael Wood (Canisius College)
• 47
Baryon-to-meson Transition Distribution Amplitudes: basic properties, physical interpretation and experimental perspectives

Baryon-to-meson Transition Distribution Amplitudes (TDAs) appear
as building blocks within the collinear factorized description of amplitudes
for a class of hard exclusive reactions such as hard exclusive meson
electroproduction off a baryon in the near-backward region and
baryon-antibaryon annihilation into a meson and a lepton pair.

In this talk we present a general overview of the fundamental properties
of baryon-to-meson TDAs and address their physical contents with the special
emphasize on the interpretation in the impact parameter space.
We also discuss the observable quantities
sensitive to the onset of the collinear factorization regime for the corresponding
hard exclusive reactions and consider experimental perspectives for accessing
baryon-to-meson TDAs at JLab and at future facilities such as PANDA@GSI and EIC.

Speaker: Dr Kirill Semenov-Tian-Shansky (PNPI)
• 48
Bound and Free Nucleon Structure

Atomic nuclei are made of protons and neutrons, themselves composed of quarks and gluons. Understanding how the nuclear environment impacts the quark-gluon structure of bound nucleons is an outstanding challenge. While the first evidence for such impact, known as the ‘EMC effect’, was observed over 35 years ago, a generally accepted explanation of the dynamics driving it is still lacking. I will present new high-energy electron-scattering data, that, combined with existing data, indicate that the underlying cause and dynamics of the EMC effect is the structure modification of close-proximity nucleons. A global analysis of deep inelastic scattering (DIS) data on the proton and on nuclei from A = 2 (deuterium) to 208 (lead) presented here, quantify the modification of the structure function of nucleons bound in atomic nuclei (the EMC effect) within the framework of a universal modification of nucleons in short- range correlated (SRC) pairs. It also allow to extracted neutron-to-proton structure function ratio (Fn/Fp) with smaller uncertainties then previous extractions.

Speaker: Prof. Eli Piasetzky (Tel Aviv University)
• Thursday, February 6
• Morning: Session 1 774/R-013

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• 49
Large Transverse Momentum

I will discuss issues related to transverse momentum dependent cross sections in
the limit that the transverse momentum is comparable to hard scales.

Speaker: Dr Ted Rogers (Old Dominion University/Jefferson Lab)
• 50
TMDs and collinear twist-3 functions in the CSS formalism

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 discuss the validity of the well-known relations, such as between the weighted TMD Sivers function and the collinear twist-3 Qiu–Sterman function, and their use in phenomenological studies of the 3-D structure of hadrons.

Speaker: Leonard Gamberg (Penn State University Berks)
• 51
Comparing single spin asymmetries in hadronic and heavy-ion collisions

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 to the apperance of baryonic cores in the quantized vortices in pionic superfluid is addressed. The experimental studies of the transition between hadronic and heavy-ion collisions is discussed.

Speaker: Oleg Teryaev (Joint Institute for Nuclear Research (RU))
• 52
Hadron structure and dynamics in Minkowski space

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 gluon dressing function, and a phenomenological quark-gluon vertex [2], which will be also discussed. A recent application to a fermion-boson system, resembling a quark-diquark model of the nucleon [3], is also reported and the associate momentum distributions will be shown. In particular for this model the issue of scale invariance is addressed. In addition, we discuss some future directions of this Minkowski space framework to describe the hadron structure.

[1] W. de Paula, T. Frederico, G. Salmè, M. Viviani, R. Pimentel,
Eur. Phys. Jour. C 77, 764 (2017).
[2]O. Oliveira, W. de Paula, T. Frederico, J. P. B. C. de Melo,
Eur. Phys. Jour. C 79, 116 (2019).
[3]J. H. A. Nogueira, V. Gherardi, T. Frederico, G. Salmè, D. Colasante, E. Pace,
Phys. Rev. D 100, 016021 (2019).

Speaker: Tobias Frederico (Instituto Tecnologico de Aeronautica)
• 10:40 AM
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• Morning: Session 2 774/R-013

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Convener: Leonard Gamberg (Penn State University Berks)
• 53
QCD factorization and hadron production near threshold

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 were produced near the threshold. In this talk, I will discuss QCD factorization that is necessary for connecting the produced hadrons to colored partons, explore the transition between the inclusive and exclusive production when hadrons are produced with a low multiplicity, and quantify our capability to measure the three-dimensional hadron structure at the newly upgraded CEBAF at JLab and the future Electron-Ion Collider.

Speaker: Dr Jianwei Qiu (Jefferson Lab)
• 54
The spin content of the nucleon sea

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.

Speaker: Prof. Bo-Qiang Ma (Peking University)
• 55
The Strong Conjecture for Confinement

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 spherical symmetry.

Speaker: Prof. Dennis Sivers (Portland Physics Institute)
• 12:25 PM
Lunch 866, Restaurant 3

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• SJB-80 774/R-013

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Convener: Gunar Schnell
• 56
Nuclei as Laboratories for QCD

Recent experimental and theoretical developments are bringing once more to the forefront how nuclear medium effects on the partonic structure of the nucleon are key for probing the fundamental properties of QCD. I will review the new progress and advancements in this field.

Speaker: Prof. Liuti Simonetta
• 57
Stan Brodsky and the 1974 November Revolution

A discussion of Stan Brodsky's work shortly before and after the discovery of the J/psi particle.

Speaker: Dennis Sivers (Portland Physics Institute)
• 58
From Light-Cone Wave Functions to Generalized Parton Distributions

Like many other quantities, Generalized Parton Distributions can
be represented in terms of Light-Cone Wave Functions. This connection has
several important physics aspects, which I review with a historical
perspective, from early work at the turn of the millenium to recent
developments.

Speaker: Markus Diehl (DESY)
• 59
The ultimate free lunch: the light-front vacuum

I will discuss the tremendous simplifications arising from a 'trivial' vacuum in the light-front formulation of field theory and how that can be reconciled with non-zero vacuum condensates and dynamical symmetry breaking.

Speaker: Prof. Matthias Burkardt (New Mexico State University)
• 3:40 PM
Coffee break 774/R-013

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Convener: Matthias Burkardt
• 60
Fock expansion of Bound States

Bound states may be approximated by their valence Fock states $|val\rangle$, with higher Fock components perturbatively generated by the Hamiltonian, $H^n|val\rangle$. In temporal ($A^0=0$) gauge Gauss' law appears as a constraint on physical states, fixing the instantaneous potential energies of all Fock components. A dimensionful parameter arises in QCD through the boundary condition on the solution of Gauss' law. This determines the confinement scale. The quantum numbers of atoms and hadrons are given by their valence states since the Hamiltonian conserves $J^{PC}$. Such approximate QCD states may serve as a model for studying TMD's and other parton distributions.

Speaker: Paul Hoyer (University of Helsinki)
• 61
Light-Front Holographic QCD: From counting rules to a unified description of parton distributions

In this talk I will present an overview of the work with Stan Brodsky on nonperturbative QCD based on the gauge / gravity correspondence and light-front quantization. I will recount how our earlier incursions into this new area have gradually evolved into an active field of research. Our endeavor has been instrumental in bringing together a wonderful team of collaborators which has contributed to unveil unsuspected connections and analytic insights into hadron structure and dynamics.

Speaker: Prof. Guy de Teramond (UCR)
• 62
A Fixed-Target Program at the LHC: the genesis

I will review the evolution of the AFTER@LHC project.

Speaker: Jean-Philippe Lansberg (Université Paris-Saclay (FR))
• 63
A Gauge Principle in Financial Markets
Speaker: Alex Langnau
• 7:00 PM
Conference dinner and SJB-80 celebration Restaurant Bois Joly

#### Restaurant Bois Joly

Route de télécabine - 01170 CROZET Tél :+33 (0)4 50 41 01 96
• Friday, February 7
• Morning: Session 1 774/R-013

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Convener: Alexey Prokudin
• 64
EIC: the science program and machine designs
Speaker: Robert McKeown (Jefferson Lab)
• 65
The LHCspin project

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<η<5) is perfectly suited for the reconstruction of particles produced in fixed-target collisions. The fixed-target configuration, with center-of-mass energies ranging from √s=115 GeV in pp interactions to √s_NN=72 GeV in collisions with nuclear beams, allows to cover a wide backward rapidity region, including the poorly explored high x-Bjorken and high x-Feynman regimes. The project has several ambitious goals regarding new-era quantitative searches in QCD through the study of the nucleon’s internal dynamics in terms of both quarks and gluons degrees of freedom. The first fundamental step of installing the unpolarized target has been already reached in LHCb with the SMOG2 system.
The status of the project is presented along with a selection of physics opportunities.

Speaker: Dr Pasquale Di Nezza (INFN e Laboratori Nazionali di Frascati (IT))
• 66
Physics with charmonia at the SPD and AMBER experiments

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 of the heavier charmonia states. The talk will cover unpolarized and polarized physics with charmonia at the SPD and AMBER experiments.

Speaker: Igor Denisenko (Joint Institute for Nuclear Research (RU))
• 67
Probing Gluon Sivers Function in J/Psi Production at EIC

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.

Speaker: Dr Asmita Mukherjee
• 10:40 AM
Coffee break 774/R-013

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• Morning: Session 2 774/R-013

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Convener: Marco Contalbrigo (INFN - National Institute for Nuclear Physics)
• 68
Advancing hadronization: From inclusive production to multiparticle correlations

Hadron structure and hadronization are flip sides of the “confinement coin,” 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. Recent results from the LHCb experiment on the hadronization of light quark jets will be shown, and prospects for future measurements at LHCb as well as the Electron-Ion Collider will be discussed.

Speaker: Christine Aidala (University of Michigan (US))
• 69
Concluding remarks
Speaker: Franco Bradamante (Universita e INFN Trieste (IT))
• 70
From the QCD Lagrangian to Hadron Structure and Interactions: A 55-Year Experience

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 last 55 years.

Speaker: Stanley J. Brodsky (SLAC National Accelerator Laboratory, Stanford University)
• 12:50 PM
Lunch 866, Restaurant 3

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• 2:00 PM
Visit to COMPASS experiment 888