Joint 20th International Workshop on Hadron Structure and Spectroscopy and 5th workshop on Correlations in Partonic and Hadronic Interactions

30 Sept 2024, 08:10 → 4 Oct 2024, 23:30 Asia/Yerevan

"Pomegranate" hall (Ramada Hotel & Suites by Wyndham, Yerevan, Armenia)

Bakur Parsamyan (AANL, Turin section of INFN and CERN), Fulvio Tessarotto (Universita e INFN Trieste (IT)), Harut Avakian (Jefferson lab), Patrizia Rossi (Jefferson Lab)

The five day long joint "20th International Workshop on Hadron Structure and Spectroscopy" and 5th workshop on "Correlations in Partonic and Hadronic Interactions" (IWHSS-CPHI-2024) will be held in Yerevan, Armenia, from 30 September to 4 October 2024.

IWHSS is a series (20 editions) of annual workshops on Hadron Structure and Spectroscopy, with most recent editions being the IWHSS-2023 (Prague, Czechia) and IWHSS-2022 (CERN, Switzerland).

CPHI is a series (5 editions) of biennial workshops on Correlations in Partonic and Hadronic Interactions, with most recent editions being the CPHI-2022 (Duke University, US) and CPHI-2020 (CERN, Switzerland).

The joint workshop will be held as a single event with a unique timetable and schedule.
The aim of the workshop is to bring together the European (CERN, COMPASS, etc.) and US (JLab, BNL, etc.) communities, strengthening existing links and creating new ones.

The scientific programme of the joint workshop will be focused on the following topics:

• Spin and 3D Structure Structure of the Nucleon
• TMDs, GPDs and GTMDs
• Fragmentation and Fracture Functions
• Fixed Target and Collider Experiments
• Meson Structure and Spectroscopy
• Search for Exotics and Baryon Resonances
• Confinement QCD and fundamental symmetries
• Dark matter/dark photon searches
• Future Measurements and Experimental proposals

One of the sessions of the workshop will be dedicated to the 50th anniversary of the "November revolution in particle physics".

Workshop Organizers:
A. Guskov, A. Bacchetta, A. Vossen, A. Bressan, B. Grube, B. Parsamyan, E. Voutier, F. Tessarotto, H. Avakian, K. Joo, L. El Fassi, L. Elouadrhiri, L. Gan, M. Battaglieri, M. Sargsian, N. d'Hose, P. Achenbach, P. Rossi. S. Stepanyan

Our sponsors and partners:

                     

Monday 30 September

08:15 Registration

1 Opening

IWHSS-CPHI-2024 - opening.pdf

Morning plenary: Session 1

2 TMD effects in polarized processes: COMPASS selected highlights

COMPASS is the longest-running experiment at CERN, with a record-breaking 20 years of data collection from 2002 to 2022. The experiment has a unique and diverse physics programme focused on nucleon structure and spectroscopy measurements.

This talk will review selected highlights from the COMPASS legacy on parton transverse momentum dependent nucleon spin structure studies and address recent results and prospects.

Speaker: Dr Bakur Parsamyan (AANL, Turin section of INFN and CERN)

Parsamyan_IWHSS-CPHI-2024.pdf

3 Highlights from the RHIC Cold QCD Program

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory is the world's only polarized proton collider with center-of-mass energies up to 500 GeV and polarizations of about 60% for each proton beam. It provides unique opportunities to study the spin structure in hadronic systems and opens new kinematic regions compared to deep inelastic scattering. The three pillars of the RHIC spin program cover the gluon polarization, sea quark helicity distributions, and transverse spin effects in hadronic systems. We will summarize recent results and discuss near term plans and their implications on parton distribution functions in the collinear and transverse momentum dependent frameworks.

Speaker: Oleg Eyser (Brookhaven National Laboratory)

IWHSS_RHIC-ColdQCD_Eyser.pdf

4 Current Status of TMD Measurements at CLAS12

The status of several CLAS12 semi-inclusive deep inelastic scattering measurements sensitive to TMDs, including several new results from a 10.5 GeV longitudinally polarized electron beam incident on a longitudinally polarized target, will be discussed. A focus will be placed on areas where CLAS12 and other fixed target experiments may be in friction with phenomenology, including effects from longitudinally polarized virtual photons, current vs target fragmentation and the contribution of diffractive vector mesons.

Speaker: Timothy Barton Hayward (MIT)

Hayward_CPHI2024.pdf

5 Hadronization in e+e- annihilation

Hadronization, the inevitable formation of colourless hadrons from coloured partons (quarks and gluons), is one of the fascinating aspects of nature and one that escapes first-principle calculations based on quantum chromodynamics. As such, experimental data are required to constrain fragmentation functions, the non-perturbative objects arising from applying factorisation theorems to various high-energy processes involving hadrons in the final state. An especially well-suited process to study hadronization is e+e- annihilation into hadrons as these hadrons are produced from the partons produced in the collision and cannot emerge from the remnants of the initial state like, e.g., in hadronic collision or lepton-nucleon scattering. In this contribution, I will review more recent results obtained on hadron production in e+e- annihilation.

Speaker: Gunar Schnell

IWHSS CPHI 2024 - Gunar.Schnell.pdf

11:00 Coffee break

Morning plenary: Session 2

6 GPD measurements at JLab: overview

Generalized Parton Distributions (GPDs) are nowadays the object of an intense effort of research, in the perspective of understanding nucleon structure. They describe the correlations between the longitudinal momentum and the transverse spatial position of the partons inside the nucleon and they can give access to the contribution of the orbital momentum of the quarks and gluons to the nucleon spin.
Deeply Virtual Compton scattering (DVCS), the electroproduction on the nucleon, at the partonic level, of a real photon, is the process more directly interpretable in terms of GPDs of the nucleon. Depending on the target nucleon (proton or neutron) and on the DVCS observable extracted (cross sections, target- or beam-spin asymmetries, …), different sensitivity to the various GPDs for each quark flavor can be exploited. Gluon GPDs can also be accessed by probing specific kinematic regimes. And, besides DVCS, other exclusive reactions, such as Timelike Compton Scattering, Double DVCS, or the exclusive electroproduction of mesons, can provide information on GPDs.
This talk will provide an overview on recent and new, promising, GPD-related experimental results, mainly obtained at Jefferson Lab on fixed target experiments with a 12-GeV electron beam, for various target types and final states. These data open the way to a “tomographic” representation of the structure of the nucleon, allowing the extraction of transverse space densities of the quarks at fixed longitudinal momentum, as well as paving the way to the quarks’ angular momentum contribution to the spin of the proton.

Speaker: Silvia Niccolai (IPN Orsay)

IWHSS_2024_niccolai.pdf

7 GPDs study at COMPASS

Deeply Virtual Compton Scattering (DVCS) and Hard Exclusive Meson Production (HEMP) are valuable processes to study Generalized Parton Distributions (GPDs). By correlating the longitudinal momentum of the partons to their transverse spatial distribution inside the nucleon, GPDs reveal the 3-dimensional structure of the nucleon in QCD. Following a test run in 2012, exclusive measurements were performed at COMPASS in 2016 and 2017 at the M2 beamline of the CERN SPS. The 160 GeV muon beam impinged on a 2.5m long liquid hydrogen target that was surrounded by a barrel-shaped time-of-flight system to detect the recoiling target proton. The scattered muons and the particles produced were detected by the COMPASS spectrometer, which was supplemented by an additional electromagnetic calorimeter for the large-angle-photon detection.
The DVCS cross section is extracted from the sum of cross sections measured with opposite beam charge and polarization, with special attention made to separate DVCS from exclusive π0 production. In the COMPASS kinematic domain, the DVCS cross section is closely related to the GPD H and gives a measure of the transverse extension of the partons in the proton, in the sea-quark regime of Bjorken-x. On the other hand, the measurement of the cross section of exclusive π0 production and the Spin Density Matrix Elements (SDMEs) of ρ0 and ω production can provide important inputs for the understanding of chiral-even and chiral-odd GPDs, as well as insights into the reaction mechanisms involved. The current progress on the study of these exclusive channels will be presented.

Speaker: Nicole D'Hose (Université Paris-Saclay (FR))

NdH_Yerevan_CPHI-IWHSS_2024.pdf

8 Insights from the SpinQuest (E1039) Experiment at Fermilab

SpinQuest, a fixed-target experiment at Fermilab, studies the Drell-Yan process by utilizing transversely polarized NH₃ and ND₃ targets alongside an unpolarized 120-GeV proton beam. The primary goal is to measure single spin azimuthal asymmetries that arise from the correlation between the transverse momentum of the struck quark and the spin of the parent nucleon, referred to as Sivers asymmetry. The angular distribution of final-state di-muons from the Drell-Yan process, in relation to the target polarization, is sensitive to one of the eight Transverse Momentum Dependent (TMD) parton distribution functions, the Sivers function, which can only be cleanly accessed in this process. Designed with optimized acceptance and kinematics to capture contributions from the target anti-quarks, SpinQuest seeks to assess the existence of orbital angular momentum (OAM) of sea quarks in the nucleon through the measurement of non-zero Sivers functions, contributing to a broader understanding of individual contributions to proton spin as well as testing the QCD prediction regarding the sign change of the Sivers function in the Drell-Yan process compared to that in semi-inclusive deep inelastic scattering (SIDIS). Additionally, the experiment aims to measure transverse single-spin asymmetries (TSSA) for J/Psi production, which are sensitive to the gluon Sivers function. This presentation will outline the current status and plans for the SpinQuest experiment.

Speaker: Liliet Calero Diaz (Los Alamos National Laboratory)

IWHSS_2024_LILIET.pdf

13:00 Lunch

Afternoon plenary: Session 1

9 Extraction of kaon PDFs from the Drell-Yan and J/Psi production data using the statistical model

We present an analysis to extract kaon parton distribution functions (PDFs) using meson-induced Drell-Yan and quarkonium production data. Starting from the statistical model, first developed for describing the partonic structure of nucleons and later applied to the pion, we have extended this approach to perform a global fit to existing kaon-induced Drell-Yan and charmonium production data. These data are well described by the statistical model, allowing an extraction of the kaon PDFs. We find that both the Drell-Yan and the charmonium data favor a harder valence distribution for strange quark than for up quark in kaon. The kaon gluon distribution is further constrained by the charmonium production data. In particular, the momentum fraction carried by gluons is found to be similar for pion and kaon.

Speaker: Jen-Chieh Peng (University of Illinois at Urbana-Champaign)

IWHSS_2024_Peng_v1.pdf

10 The Proton Radius Puzzle: An Overview

The proton charge radius is one of the pivotal quantities in physics. In particular, its value is highly correlated with the experimental determination of the Rydberg constant. For the past seventy years it has been measured through elastic electron-proton scattering and ordinary hydrogen spectroscopy methods. Over the years, results from both methods generally agreed with each other within their experimental uncertainties. Unexpectedly, in 2010 (and 2013) two experiments from newly developed muonic hydrogen atomic spectroscopy method reported results up to six standard deviations smaller values than the accepted average from all previous experiments performed with both methods. This discrepancy triggered the well-known proton radius puzzle in hadronic physics. This talk will discuss the post-2010 progress in proton radius measurements, together with the recent experimental results and plans for new experiments. In particular, a novel magnetic-spectrometer-free electron-proton scattering experiment (PRad), performed at Jefferson Lab in 2016, and the status of the second experiment (PRad-II), will be presented emphasizing the method and published results.

Speaker: Ashot Gasparian (North Carolina A&T State University)

Gasparian_Yerervan_Workshop_2024.pdf

11 Study of Hadronization Dynamics via Electroproduction off Nuclei at Jefferson Lab

In this talk, I will highlight recent semi-inclusive deep inelastic scattering (SIDIS) studies carried out at Jefferson lab to probe hadronization mechanisms and associated medium modifications of the underlying structure of atomic nuclei, with a focus on the first-ever SIDIS Lambda production in the current and target fragmentation regions. These new results, alongside the lately collected CLAS12 quark propagation data, will effectively improve our understanding of fragmentation mechanisms related to color propagation and hadron formation in cold nuclear matter and provide potential insights into quark-diquark correlations in the nucleon, light, and strange baryon structures.

This work is supported in part by the U.S. DOE award #:~DE-FG02-07ER41528.

Speaker: Lamiaa El Fassi (Mississippi State University)

IWHSS-CPHI24Hadz-LE.pdf

12 Meson spectroscopy through photoproduction: from Jefferson Lab to the EIC

This talk will present an overview of the light quark meson spectroscopy program with Jefferson Lab's 12 GeV electron beam facility, including recent results from the GlueX collaboration. In addition, the prospects for extending the study of meson spectroscopy to the charmonium sector, utilizing the unique photoproduction mechanism, will be discussed in the context of a potential energy upgrade to 22 GeV at Jefferson Lab and the Electron Ion Collider.

Speaker: Justin Stevens

iwhss_stevens.pdf

16:00 Coffee break

Afternoon plenary: Session 2

13 Science and Status of the Electron Ion Collider (EIC) at BNL

In 2018 the US National Academy of Science, Engineering and Medicine upon asked to evaluate the science case for the EIC, said that the science of EIC is fundamental and its realization timely. Since then the US department of Energy office of Nuclear Physics has moved forward towards realizing the collider. The EIC will be built at BNL using the RHIC complex in a partnership between BNL and JLab. ePIC, a new detector collaboration has been formed and is working towards finalizing the design and realization the detector. In this talk I will summarize the science and status the EIC project.

Speaker: Abhay Deshpande

EIC at Yerevan present.pdf

14 The Jefferson Lab 22 GeV Upgrade

The initial scientific case for upgrading the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab (JLab) to 22 GeV will be presented. The proposed physics program encompasses a large and diverse range of transforamtive investigations centered around the non-perturbative dynamics inherent in hadron structure and the exploration of strongly interacting systems. It builds upon the unique capabilities of CEBAF high-luminosity operations, the availability of existing or planned Hall equipment, and recent advancements in accelerator technology. Highlights and some key measurements will be discussed, with emphasis on the significant physics outcomes and unique aspects of these programs that distinguish them from other existing or planned facilities.

Speaker: Patrizia Rossi (Jefferson Lab)

Rossi_Yerevan_indico.pdf

15 The LHCspin project

The goal of LHCspin is to develop innovative solutions and cutting-edge technologies to advance the field of spin physics over the next few years, by exploring a unique kinematic regime and exploiting new reaction processes. To achieve this, a polarized gaseous target, operated in combination with high-energy, high-intensity LHC beams and the highly performing LHCb particle detector, has the potential to open new physics frontiers and deepen our understanding of the complexities of the strong interaction in the non-perturbative regime of QCD. This configuration, with center of mass energies up to 115 GeV, using both proton and heavy-ion beams, covers a broad backward rapidity region, including the poorly explored high Bjorken-x and high Feynman-x regimes. This ambitious task is based on the recent installation of an unpolarized gas target (SMOG2) in the LHCb spectrometer, not only making it a unique project but also providing a valuable playground for its polarized upgrade. LHCspin is expected toc start data taking in the LHC IR4 in few years, as an independent system before going to LHCb. Here, an overview of the physics potential and a description of the LHCspin experimental setup are presented.

Speaker: Pasquale Di Nezza (INFN e Laboratori Nazionali di Frascati (IT))

LHCspin Yerevan Sep 2024.pdf

16 The November Revolution - a personal approach

Many of the physicists working in this field were not alive in 1974 and many others have not heard of the November Revolution. We give that name to an event at the SLAC Auditorium on November 11, 1974 when teams from Brookhaven and SLAC announced the remarkable results that heralded the discovery of the fourth quark, charm. This discovery led, very quickly, to the Standard Model of Particle Physics.

Speaker: Dennis Sivers (Portland Physics Institute)

Presentation1 Yerevan.pdf

19:00 Welcome receiption

Tuesday 1 October

Tuesday Morning: Session 1

17 J/psi production as a probe of gluon TMDs

I will discuss several processes involving J/psi production which would allow for the extraction of gluon TMDs in present and future experiments at the LHC and the EIC.

Speaker: Cristian Pisano (University and INFN Cagliari (Italy))

IWHSS-2024-Cristian-Pisano.pdf

18 Probing the Partonic Structure through Target Fragmentation in SIDIS

Semi-Inclusive Deep Inelastic Scattering (SIDIS) provides a unique window into the internal structure of the nucleon, especially through the study of target fragmentation. In this talk, I will present recent advances in understanding SIDIS within the fracture function formalism, with special emphasis on the role of gluonic contributions and higher-twist effects in generating azimuthal asymmetries. Additionally, I will explore the connection between fracture functions and nucleon energy correlators, offering a novel approach to examining target fragmentation through the energy distribution patterns observed in DIS.

Speaker: Xuanbo Tong

FrF_IWHSS-CPHI 2024.pdf

19 Studying Drell-Yan at NLO with the Parton Branching Method

The Drell-Yan process is an important probe of TMD densities at high energy. In this contribution, we present the status of phenomenology based on TMDs computed in the Parton Branching Method, comparing the predictions to experimental results up to LHC energies. We demonstrate that existing measurements are sensitive to the inner proton structure and highlight the role of TMD evolution.

Speaker: Louis Moureaux (Hamburg University (DE))

Moureaux_PB-TMD_IWHSS-CPHI_Yerevan.pdf

20 Extraction of charged pion and kaon fragmentation functions at NNLO

In this contribution, I will present a determination of unpolarised charged pion and kaon fragmentation functions (FFs) from a set of single-inclusive electron-positron annihilation (SIA) and lepton-nucleon semi-inclusive deep-inelastic scattering (SIDIS) data. The determination is carried out in a framework that combines a neural-network parametrisation of fragmentation functions with a Monte Carlo representation of their uncertainties. It includes exact next-to-next-to-leading (NNLO) order QCD corrections to SIA and approximated NNLO corrections to SIDIS. In view of the recent computation of exact NNLO corrections to SIDIS, I will also comment on their impact on FFs.

Speaker: Dr Valerio Bertone (C.E.A. Paris-Saclay)

bertone_IWHSS2024_30_09_2024.pdf

21 Polarized hadronization in Pythia

The status of the implementation of spin effects in the Pythia hadronization via the StringSpinner package is reviewed. The package is then used for simulations of e+e- annihilation, and the resulting Collins asymmetries for back-to-back hadrons are shown and compared with the BELLE and BABAR data. The Collins analyzing power resulting from the string+3P0 model is extracted and compared to phenomenological results.

Speaker: Albi Kerbizi (Universita e INFN Trieste (IT))

Kerbizi_IWHSS-CPHI-2024.pdf

10:55 Coffee break

Tuesday Morning: Session 2

22 TMD overview

In this opening talk, I will discuss the status of TMD studies, focusing on some recent developments and some open aspects

Speaker: Alessandro Bacchetta

Bacchetta_Yerevan2024.pdf

23 Upgrade of ART23: TMDs fit to SIDIS data

Building on the concluded study of ART23,
we provide a simultaneous fit to DY and SIDIS data,
constraining both TMDPDFs as well as TMD fragmentation functions.
I will discuss the challenges and status of the project, including (preliminary) results.

Speaker: Valentin Moos

VMoos_ART23Upgrade.pdf

24 Extraction of flavour dependence in unpolarized TMDs

A deeper understanding of the three-dimensional structure of nucleons requires separating how different flavours contributes to transverse momentum distributions. We present an initial step in this exploration, with the latest results by the MAP Collaboration on the extraction of unpolarized quark Transverse Momentum Dependent Distributions and Fragmentation Functions from global fits of Drell-Yan and SIDIS data. With the introduction of flavour dependence in nonperturbative models, we obtain significant differences in the TMD shape among different quarks and final-state hadrons.

Speaker: Filippo Delcarro (Università di Pavia (IT))

Delcarro_IWHSS2024.pdf

25 Understanding the large $k_T$ behavior in TMD PDFs

The main aspect of factorization relies on both the universality of the distributions as well as their interpretations as describing the internal structure of the hadrons. We present a novel approach which is best suited for hadron structure studies as it is built to both satisfy theoretic constrains originating from their operator definitions, as well as clearly demarcating the perturbative contributions from the nonperturbative ones.
Some practical examples in a Drell-Yan phenomenological analysis are studied as well as preliminary results for the Sivers function.

Speaker: TOMMASO RAINALDI (Old Dominion University)

Rainaldi_IWHSS_CPHI.pdf

26 Round table: "Reforming" SIDIS

Speakers: Harut Avakian, et al.

2024-Oct-1-reforming-sidis.pdf

2024-Oct-1-reforming-sidis.pptx

Stan-ddis_Oct2024.pdf

13:25 Lunch

Tuesday Afternoon: Session 1

27 Multi-messenger studies of nuclear short-range correlations

Short-Range Correlations (SRC) refer to pairs of nucleons that exhibit high relative momentum while maintaining low center-of-mass momentum. Over the past decade, extensive investigations, primarily using electron scattering,have revealed that SRCs predominantly consist of neutron-proton pairs, which significantly contribute to the high-momentum tail of nuclear wave functions.

Recent advances in SRC research, employing hadronic probes in inverse kinematics, have introduced new opportunities for studying SRCs
through hard quasi-free exclusive scattering reactions. This contribution provides an overview of the current challenges in SRC research and highlights recent experimental developments.

Speaker: Dr Maria Patsyuk (JINR)

Yerevan24_MPatsyuk.pdf

28 Experimental efforts searching for the onset of Color Transparency

Searching for the onset of Color Transparency (CT) is a vibrant experimental effort to observe hadrons in a small neutral transverse size configuration in the nucleus. The observation of the onset of CT lies at the intersections between the quark-gluon degrees of freedom and the nucleonic descriptions of nuclei. CT is fundamentally predicted by quantum chromodynamics and is expected to be observable in exclusive scattering as a reduction of final state interactions (FSI) of the point-like hadron with the nuclear medium. Experimentally, this would yield a rise in the measured transparency of the point-like hadron with increasing four-momentum transferred. The most recently published experimental effort to observe the onset of CT for protons took place in Jefferson Lab using an electron beam on a carbon target. This experiment ruled out the observation of CT for the proton up to $Q^2$=14 GeV$^2$, in contrast to theory expectations. The electron beam energies at Jefferson Lab provide an ideal energy range to search for the onset of CT in other reactions including a recent photoproduction experiment in Hall D and future experiments exploring pion electroproduction and proton knockout in rescattering kinematics from deuterium. This talk will present the current experimental status of the recent experiments and opportunities in the near future measurements at Jefferson Lab.

This work was funded in part by the U.S. Department of Energy, including contract AC05-06OR23177 under which Jefferson Science Associates, LLC operates Thomas Jefferson National Accelerator Facility.

Speaker: Holly Szumila-Vance (Florida International University)

IWHSS_CT_2024.pdf

29 SRC studies with proton probes

Nuclear structure at short NN distances is still poorly known. In the past, most experiments studied either A(e,e'pN) or A(p,ppN) processes without identification of the state of the residual nucleus. It was even not always clear whether the residual (A-2) nucleus survives and is not broken. (The exception are the experiments at NIKHEF and MAMI on the 16O(e,e'pp)14C process where the 0^+ ground state of 14C was resolved allowing to select 1S_0 state of the pp-pair.) Nowadays, the availability of the nuclear beams allows to use the inverse kinematics with proton target at rest in order to detect the residual nucleus and eventually to determine its quantum state. This opens up the possibility to filter-out certain internal quantum states of the short-range correlated (SRC) pair and the states of the relative motion of the pair and the residual nucleus. Theoretical description of such fully exclusive reactions needs fully quantum models. In this talk, the approach based on the translationally-invariant shell model to describe SRC reactions will be discussed. Calculations were performed for reactions 12C(p,ppn)10B and 12C(p,ppp)10Be with carbon beam at 48 GeV/c, studied by BM@N collaboration at JINR, see refs. [1,2] for detail.

[1] M. Patsyuk et al., Nature Phys. 17, 693 (2021) [arXiv:2102.02626]

[2] A.B. Larionov, Yu.N. Uzikov, Phys. Rev. C 109, 064601 (2024) [arXiv:2311.06042]

Speaker: Alexei Larionov

larionov_Yerevan2024.pdf

30 Light-front densities of the polarized deuteron

High-energy reactions on nuclei are conveniently described using light-front quantization. I discuss how especially in tagged processes on the deuteron, the light-front densities of the polarized deuteron enter. I discuss their properties (of relevance to polarized measurements) and some similarities to partonic TMDs.

Speaker: Wim Cosyn (Florida International University)

Cosyn_Yerevan.pdf

31 Coherent gluon radiation in pA collisions: beyond leading-log accuracy

After recalling the main features of fully coherent energy loss (FCEL) suffered by an energetic parton in high-energy proton-nucleus (pA) collisions, I will present results for the associated gluon radiation spectrum beyond leading-logarithmic accuracy, for all 2 —> 2 partonic channels in perturbative QCD.

Speaker: Stephane Peigne

Peigne-Yerevan-2024.pdf

16:10 Coffee break

Tuesday Afternoon: Session 2

32 Dark Sector physics: candidates and searches

I will review the main particle candidates to constitute the dark matter in the Universe. I will discuss the state-of-the-art searches of some of the candidates both with accelerator experiments and with astrophysical techniques.

Speaker: Prof. Fiorenza Donato (Torino University)

IWHSS_Armenia.pdf

33 AMBER Antiproton Production Measurements: A Contribution to Dark Matter Search

One of the indirect detection method of dark matter (DM) is based on the search of the products of DM annihilation or decay. They should appear as distortions in the gamma rays spectra and in the rare Cosmic Ray (CR) components, like antiprotons, positrons and antideuterons, on top of the standard astrophysical production. In particular, the antiprotons in the Galaxy are mainly of secondary origin, produced by the scattering of cosmic proton and helium nuclei off the hydrogen and helium in the interstellar medium (ISM). In order to obtain a significant sensitivity to DM signals, accurate measurements of the antiproton production cross section in p-p and p-He collisions are crucial. The AMBER experiment at CERN collected in 2023 the first data ever in p-He collision at a center of mass energy from 10 to 21 GeV. The 2024 AMBER program with proton beam on liquid hydrogen and deuterium targets is also described.

Speaker: Davide Giordano (INFN Torino)

Giordano_IWHSS2024.pdf

34 Dark sector searches at the electron accelerator MESA

The existence of dark matter has been supported by decades of accumulating evidence, making it one of the most compelling unsolved mysteries in modern physics. While its presence is widely accepted, the true nature of dark matter remains elusive. Among the many experimental strategies to probe this enigma, fixed-target experiments at particle accelerators offer a promising avenue, with the MESA accelerator set to play an important role in future investigations.
MESA is a high-intensity electron accelerator operating in the low-energy regime, currently under construction at the Institute for Nuclear Physics at the Johannes Gutenberg University Mainz, Germany. It hosts three key experiments - MAGIX, P2, and DarkMESA - each contributing to a diverse and ambitious physics program. As the first accelerator combining the innovative concept of energy recovery with high-precision physics measurements, MESA will provide two operation modes: an energy recovery mode and an extracted beam mode.
A primary objective of MESA's research is to explore the dark sector, a potential solution to the dark matter puzzle. Both MAGIX and DarkMESA are crucial to this effort. MAGIX is a high-resolution, two-spectrometer experiment utilizing an internal gas jet target in MESA’s energy recovery mode, while DarkMESA is a beam-dump experiment situated behind the P2 experiment that will be operated in extracted beam mode. Together, these experiments are designed to perform precise and competitive measurements sensitive to light dark matter (LDM) models.
This talk will present an overview of the dark sector searches planned at MAGIX and DarkMESA.

Speaker: Sebastian Stengel

DarkSectorSearchesAtTheElectronAcceleratorMESA.pdf

35 The Beam Dump eXperiment at Jefferson Lab

The Beam Dump Experiment (BDX) at Jefferson Laboratory (JLAB) is electron-beam thick-target experiment to search for Light Dark Matter (LDM) particles in the MeV-GeV mass range. BDX will exploit the high-intensity 10.6 GeV e beam from CEBAF accelerator impinging on the beam dump of experimental Hall-A, collecting up to 10^22 electrons-on-target in a few years time. Any LDM particles produced by the interaction of the primary e beam with the beam dump will be detected by measuring their scattering inside a detector, which is to be installed in a dedicated underground facility, located 20 m downstream. The space between the beam dump and the detector will be filled with heavy shielding to suppress the high-energy component of the beam-related backgrounds. The BDX detector consists of electromagnetic calorimeter (ECAL) made of a matrix of inorganic scintillating crystals, surrounded by a hermetic veto system. The expected signature for the LDM interaction in the ECAL is an O(100 MeV) electromagnetic shower with no activity in the surrounding active veto counters.

After an intense phase of R&D studies and simulations with on-site background measurements conducted to validate the corresponding results, the BDX proposal received full approval by the 2019 JLab Program Advisory Committee. The collaboration is actively working on the design of the new experimental facility for housing the experiment.

A small-scale version of the full experiment, BDX-MINI, has been built and operated with a lower energy beam, where the existing soil between the beam dump and the detector provided adequate shielding from known particles produced in the beam dump. The BDX-mini detector, installed in a well located 22 m downstream of the Hall-A beam dump, consisted of a PbWO electromagnetic calorimeter, surrounded by a layer of tungsten shielding and two hermetic plastic scintillator veto systems. Despite the small interaction volume, the large accumulated charge of 2.2 EOT allowed for the BDX-mini measurement to set competitive exclusion limits on the LDM parameters space, comparable to those reported by larger-scale efforts.

In this talk, after a brief introduction to the LDM physics case, we will present an overview of BDX, discussing the main items of the R&D and design phase of the experiment. We will then show the results obtained from the BDX-mini experiment, focusing on few key aspects of the associated experimental campaign and data analysis effort

Speaker: Mariangela Bondi (INFN - Sezione di Catania)

IWHSO_2024-Bondi.pdf

Wednesday 2 October

Wednesday Morning: Session 1

36 Heavy- and light-quark mesons: A theory perspective

I will review the current status of meson spectroscopy, with particular focus on exotic candidates. I will discuss the theory and analysis tools that are commonly used to calculate the spectrum and to compare with data, both in the light and heavy sector.

Speaker: Alessandro Pilloni (Messina U. & INFN Catania)

perspective.pdf

perspective.pptx

37 Exotic heavy-quark states at LHCb and Belle (II)

A vast number of new hadrons have been discovered in recent years, a large proportion of them by Belle and LHCb. Many of these new hadronic states do not fit into the traditional quark model, and their nature is yet to be understood. Progress in this field requires advances both in theory and experiment. This contribution presents recent results in heavy hadron spectroscopy from Belle II and LHCb.

Speaker: Jonas Rademacker (University of Bristol (GB))

ExoticSpectroscopy_BelleLHCb_JR.pdf

38 QCD and Strange Baryon Spectrum

Recently, numerous excited states have been observed in heavy hadron decays and beam experiments, with some interpreted as exotic candidates beyond the traditional three-quark model. In this talk, I will provide a brief overview of the recent progress in strange baryon spectroscopy and introduce a new experiment utilizing a GeV-photon beam at SPring-8/LEPS2.

Speaker: Masayuki Niiyama (Kyoto Sangyo University)

IWHSS-CPHI-2024_niiyama.pdf

39 Baryon Spectroscopy at GlueX

Photoproduction of hadrons is an important experimental tool to understand the generation of hadrons as bound systems of quarks and gluons in the non-perturbative regime of QCD. The GlueX experiment, which is located in Hall D of Jefferson Lab, uses an intense photon beam with energies of up to 12 GeV that is incident on a liquid hydrogen target. A large acceptance spectrometer with near-complete neutral and charged particle coverage provides the excellent opportunity to study many different photoproduction processes. While the primary goal of the GlueX experiment is to study the spectrum of light-quark hybrid mesons, the GlueX data allows to get new insights into the baryon spectrum ranging from $N^*$, $\Delta^*$ resonances to single and doubly strange baryons, and to the photoproduction of charmonium states near threshold.
Highlights of baryon spectroscopy results from the GlueX experiment will be discussed.

Speaker: Ms Farah Afzal (HISKP, University of Bonn)

talk_IWHSS-CPHI24_afzal.pdf

40 Overview of the 30 GeV/c Proton-Proton Physics Program at FAIR

The Facility for Antiproton and Ion Research (FAIR) in Darmstadt has begun installing accelerator components and will soon begin commissioning. The main driving synchrotron the SIS100 will provide a wide range of beams, including an intense proton beam with up to 30 GeV/c. Currently, the physics potential to expand the program of the CBM detector to include measuring exclusive final states from proton-proton interactions is being explored. In this talk I will present the potential for a broad physics program in hadron spectroscopy and structure at CBM.

Speaker: James Ritman (GSI Darmstadt & Forschungzentrum Jülich)

IWHSS_Oct24_JRitman.pdf

10:40 Coffee break

Wednesday Morning: Session 2

41 Accessing GPDs at the LHC

An introduction on the study of exclusive processes in hadron-hadron colliders will be given. This will be followed by results of measurements of exclusive processes at the LHC. Where applicable, parallels with measurements in lepton-hadron interactions will be highlighted.

Speaker: Charlotte Van Hulse (University of Alcalá)

iwhss24.pdf

42 Towards precise phenomenology of GPDs

In my talk, I will focus on the problem of model dependency affecting the phenomenology of generalized parton distributions (GPDs). I will argue that a lot of useful information on nucleon structure can already be accessed from the amplitudes of exclusive processes, particularly thanks to recently developed techniques based on Froissart-Gribov projections. Another way to avoid model dependency is by measuring processes such as double deeply virtual Compton scattering (DDVCS), or by augmenting the phenomenology of GPDs with lattice QCD results. I will touch on these subjects as well.

Speaker: Paweł Sznajder (National Centre for Nuclear Research)

sznajder_iwhss_0924.pdf

43 Studies of Transversity GPDs in Exclusive Reactions

A longstanding objective in nuclear and particle physics is to describe the three-dimensional structure of the nucleon in terms of quark and gluon fields. In this context, exclusive electron scattering experiments, where all final state particles are measured, play a significant role. Examples include electron elastic scattering, deeply virtual Compton scattering (DVCS), and deeply virtual meson electroproduction (DVMP). Exclusive electron scattering reactions at high momentum transfers are directly related to the Generalized Parton Distributions (GPDs) of quarks and gluons. Most reactions studied, such as DVCS and vector meson electroproduction, are primarily sensitive to chiral-even GPDs. However, pseudoscalar meson electroproduction, particularly the production of π0 and η mesons, has been identified as especially sensitive to parton helicity-flip subprocesses.
Dedicated experiments to study deeply virtual meson production have been conducted at Jefferson Lab. A comparison of these experimental results with theoretical models will be presented, along with a discussion on the extraction of transversity GPD parameters through a global fit of the available data.

Speaker: Valery Kubarovsky

V_Kubarovsky_Yerevan.pdf

44 First Measurement of Deeply Virtual Compton Scattering on the Neutron with Detection of the Active Neutron

Measuring Deeply Virtual Compton Scattering (DVCS) on the neutron is one of the necessary steps to understand the structure of the nucleon in terms of Generalized Parton Distributions (GPDs). Neutron targets play a complementary role to transversely polarized proton targets in the determination of the GPD E. This poorly known and poorly constrained GPD is essential to obtain the contribution of the quarks' angular momentum to the spin of the nucleon. DVCS on the neutron was measured for the first time selecting the exclusive final state by detecting the neutron, using the Jefferson Lab longitudinally polarized electron beam, with energies up to 10.6 GeV, and the CLAS12 detector. The extracted beam-spin asymmetries, combined with DVCS observables measured on the proton, allow a clean quark-flavor separation of the imaginary parts of the GPDs H and E. This talk will provide details on the data analysis leading to the long-awaited to-be-published results along with a discussion of the impact of this new data.

Speaker: Adam HOBART (IJCLab CNRS-IN2P3)

IWHSS-CPHI_2024_AH.pdf

12:30 Lunch

Wednesday Afternoon: Session 1

45 Tests of fundamental symmetries via π0, η and η′

The decays of the light meson π0, η and η′ offer a flavor-conserving laboratory to assess the low-energy QCD and to search for new physics Beyond the Standard Model. The QCD symmetries and symmetry breakings at low-energy, such as the chiral symmetry or the axial anomalies, are manifested in their most unambiguous form in the sector of light pseudoscalar mesons. An experimental study of various decays will yield light on our understanding of the origin and the dynamics of QCD confinement. In addition, the η/η′ meson has quantum numbers of vacuum (except parity) with its strong and electromagnetic decays being either anomalous or forbidden to the lowest order due to symmetries or angular momentum conservation. This enhances the relative importance of higher order contributions, making the rare η/η′ decays a sensitive hadronic probe for weakly-coupled new forces. Searching for sub-GeV dark gauge boson candidates, and the C-violating, P-conserving interactions in various η/η′ decays will extend our knowledge of the dark sector and explore new sources of CP violation to explain the observed matter and anti-matter asymmetry in the universe. The status of experimental activities at JLab and the future new opportunities will be discussed.

Speaker: Liping Gan

Gan-Armenia.pdf

46 Lorentz invariance violation from gamma ray bursts

Lorentz invariance violation (LV) can be examined through the time delay between high-energy and low-energy photons in gamma-ray bursts (GRBs). Previous studies determined the Lorentz violation energy scale as $E_{\rm LV} \simeq 3.60 \times 10^{17}$~GeV using Fermi Gamma-ray Space Telescope (FGST) data. We update the time delay model and reaffirm these findings with new observations.

Speaker: Prof. Bo-Qiang Ma (Peking University)

new-physics2410armenia.pdf

47 Alternative Method for Measuring the Radius of the Deuteron

New method is presented for measuring the radius of the deuteron that can help to resolve the current discrepancies between muon-deuteron, electron-deuteron spectroscopic as well as electron-deuteron scattering measurements.

Speaker: Misak Sargsian (Florida International University)

Yerevan24_Sargsian.pdf

48 Status of the MUSE experiment

The MUon proton Scattering Experiment (MUSE) at the Paul Scherrer Institute (PSI) was motivated by the proton radius puzzle. We obtain simultaneous high-precision measurements of elastic electron-proton and muon-proton scattering, alternating between positively and negatively charged leptons. The experiment will test lepton universality by comparing electron to muon scattering, will determine two-photon exchange by comparing scattering of positive to negative charged leptons, and will extract the proton charge form factor and radius from the cross sections. The experiment runs at beam momenta of 115, 160, and 210 MeV/c to cover the low-Q2 region of Q2 = 0.002 to 0.082 GeV2 which is maximally sensitive to the proton charge radius. In addition, because the beam includes electrons, muons and pions, we obtain pion-proton elastic scattering data. To date, MUSE has commissioned its experimental systems to the level needed for the measurements and performed a careful studies of the electron and muon beam properties in the PiM1 channel. As of mid 2024, MUSE has obtained nearly half of its planned scattering data, and currently is continuing to simultaneously measure elastic electron and muon scattering from a liquid hydrogen target. An overview of the MUSE experiment and current status will be given in this talk.

The MUSE experiment is supported by the US National Science Foundation and Department of Energy, PSI, and the US-Israel Binational Science Foundation.

Speaker: Dr Tigran Rostomyan (Paul Scherrer Institut)

T.Rostomyan_MUSE_2024.10.02.pdf

49 Gravitational form Factors and mechanical properties of a dressed quark

The form factors of the energy-momentum tensor give information on the pressure, energy and angular momentum distributions among quark and gluons inside the proton. We discuss the distributions of pressure and angular momentum inside a quark state dressed with one gluon.

Speaker: Prof. Asmita Mukherjee (IIT Bombay)

armenia_2024.pdf

15:15 Coffee break

Wednesday Afternoon: Session 2

50 The cold QCD program at sPHENIX

sPHENIX is a new experiment on the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. Its goal is to complete the scientific mission of RHIC in the study of the quark-gluon plasma and cold QCD effects.
The detector is designed to provide precision vertexing, tracking and electromagnetic and hadronic calorimetry in the central pseudorapidity region |η| < 1.1, with full azimuth coverage. It was commissioned in 2023 with Au-Au collisions and is currently taking physics data with transversely polarized proton+proton collisions at the center-of-mass energy of 200 GeV. The cold QCD program of sPHENIX will be discussed.

Speaker: Audrey Francisco (CEA)

IWHSS-CPHI-2024.pdf

51 SPD project at NICA

The SPD experiment will operate at one of the two interaction points of the NICA collider facility at JINR. The collider will provide polarized proton and deuteron beams for $pp$ and $dd$ collisions with the c.m.s. energy up to $\sqrt{s} = 27$ GeV and $\sqrt{s_{NN}} = 13.5$ GeV, respectively. The primary goal of the experiment is to study the polarized and unpolarized gluon structure of proton and deuteron. The gluon TMD functions (helicity, Sivers, Boer-Mulders, and gluon transversity in the case of deuterons) will be probed with the open charm, charmonia, and prompt photon production. In addition to the primary goals of the experiment, the physics program of the experiment extends to investigation of various aspects of QCD. This talk will give an overview an overview of the physics program, the experimental setup and the status of the project.

Speaker: Igor Denisenko (Joint Institute for Nuclear Research (RU))

IWHSS-CPHI24-Denisenko.pdf

16:30 Cognac tasting in ArArAt factory

Thursday 3 October

Thursday Morning: Session 1

52 Radiative Corrections in SIDIS: Current Status and Perspectives

The current status and perspectives in the area of radiative correction calculations in semi-inclusive hadron leptoproduction of polarized particles are discussed. Recent progress in exact and leading log calculations, Monte Carlo generators, numeric results for kinematics of modern experiments, and the procedure of radiative corrections of experimental data in real data analyses are discussed. We present the basic steps of radiative correction calculations in SIDIS including the extraction and cancellation of the infrared divergence and the approaches for all-type contributions of the lowest order such as the infrared-free sum of the effects of real and virtual photon emission and the contribution of the radiative tail from exclusive peak. We demonstrate how leading log formulae can be obtained using the standard approaches to the leading log approximation as well as from the exact expressions for the radiative correction of the lowest order, and how the method of the electron structure function is used to calculate the higher order corrections. The results are analytically compared to the results obtained by other groups. Numeric illustrations are given in the kinematics of the modern experiments at Jefferson Laboratory.

Speaker: Igor Akushevich

Akushevich_Oct_2024.pdf

53 SIRADGEN: Monte Carlo generator for simulation of radiative events in polarized SIDIS

A new Monte Carlo generator for simulation of the events with unobservable hard photon including the exclusive radiative tail in semi-inclusive deep inelastic scattering of polarized particles is presented. Simulation strategy, structure of the contributions to the observed cross section, cross-checks are presented and briefly discussed.

Speaker: Dr Alexander Ilyichev

Ilyichev_Erevan.pdf

54 TMDPDFs extractions employing AI

Transverse Momentum Dependent Parton Distribution Functions (TMDPDFs) can be extracted from deep processes such as Drell-Yan (DY), Semi Inclusive Deep Inelastic Scattering (SIDIS), and $e^+$ $e^-$ annihilation. At the leading-twist, there are two time-reversal odd TMDPDFs, namely the Sivers function and the Boer-Mulders function have connections to the partons' orbital angular momenta contributing to the overall angular momentum of the parent hadron. Deep Neural Networks (DNNs) have emerged as a powerful tool for information extraction and modeling. DNN models can be built and trained with minimal bias to predict the TMDPDFs based on fits to data. This talk will present details of the first-ever application of DNNs in extracting TMDPDFs, focusing on the flavor-dependent extraction of the Sivers functions in $SU(3)_{flavor}$.

Speaker: Ishara Fernando (University of Virginia)

IsharaFernando_IWHSS-CPHI-2024.pdf

55 Artificial Intelligence in CLAS12

In recent years, AI/ML techniques have become common practice in particle physics experiments. In this talk, I will review how AI/ML is used in the CLAS12 experiment at Jefferson Lab, to enhance its capabilities in online monitoring, triggering, reconstruction efficiency, and data analysis.

Speaker: Raffaella De Vita

devita_iwhss-cphi-2024.pdf

10:20 Coffee break

10:50 Excursions

19:30 Conference Dinner

Friday 4 October

Friday Morning: Session 1

56 Electron-Ion Collider in China

In this talk, an overview of the physics program, the detector conceptual design, and the project status will be presented. The Electron-Ion Collider in China (EicC) is a proposed high energy nuclear physics facility to be constructed based on the High Intensity heavy-ion Accelerator Facility (HIAF) in Huizhou, China. EicC will be able to place highly polarized ($\sim$80%) electrons in collisions with different ions from polarized ($\sim$70%) protons and helium-3 to unpolarized heavier nuclei up to uranium with viable center of mass energies from 10 to 20 GeV and with the luminosity of (2-4) $\times$ $10^{33}$ cm$^{-2}$s$^{-1}$. This versatility makes EicC an ideal machine to explore the 3D structure of proton in the sea quark region, the partonic structure of nuclei and the parton interaction with the nuclear environment, the exotic states, and origin of mass. In order to perform above precision measurements, a hermetical detector system will be constructed with the cutting-edge technology.

Speaker: Jinlong Zhang (Shandong University)

EicC_IWHSS-CPHI_Zhang.pdf

57 QCD physics in the Future Super Tau-Charm Facility

The proposed super tau-charm facility (STCF) is a symmetric electron-positron collider, designed to provide $e^+e^−$ interactions at a center-of-mass energy from 2.0 to 7.0 GeV. This energy region corresponds to the transitions between non-perturbative quantum chromodynamics (QCD) and perturbative QCD. Hence, a large variety of topics in elementary particle physics can be pursued at STCF, including exploring QCD and hadron spectroscopy, precisely measurement of electroweak interactions and flavor physics as well as searching for the new physics beyond the standard model. The peaking luminosity at STCF is designed to be at least $0.5×10^{35}$ cm$^{−2}s^{−1}$ and is expected to deliver more than 1 ab$^{−1}$ of integrated luminosity per year. In this talk, the physics potentials will be introduced, especially the QCD studies on fragmentation functions, form-factors and hadron spectroscopy.

Speaker: Xiao-Rui Lyu (University of Chinese Academy of Sciences)

LYU-STCF2024.pdf

58 Address from the Alikhanyan National Science Laboratory director: AANL contribution to nucleon spin structure and spectroscopy-related projects

Speaker: Dr Gevorg Karyan (A. I. Alikhanyan National Science Laboratory)

10:10 Coffee break

Friday Morning: Session 3

59 Radiative correction for unpolarized SIDIS at COMPASS

The transverse momentum squared $P_T^2$ distributions of charged hadrons produced in deep inelastic scattering and the azimuthal modulations in their angular distributions provide valuable insight into the transverse motion of partons. Using unpolarized semi-inclusive deep inelastic scattering data collected by the COMPASS Collaboration in 2016 and 2017 on proton target with longitudinally polarized muon beam, we have extracted the $P_T^2$ distributions and three azimuthal modulations.
For the same data, the COMPASS Collaboration recently evaluated corrections for the QED radiative effects using the DJANGOH Monte Carlo generator. Their effect on unpolarized sem-inclusive measurements will be presented.

Speaker: Vendula Benesova (Charles University (CZ))

IWHSS_CPHI_2024.pdf

60 Measurement of $A_{LU}$ in semi-inclusive production of $\pi^+K^-$, $K^+\pi^-$, and $K^+K^-$ pairs in deep inelastic scattering with CLAS12

Semi-inclusive deep inelastic scattering (SIDIS) measurements provide crucial experimental insight into the three-dimensional momentum structure and spin structure of nucleons. The additional degree of freedom when observing two hadrons in the semi-inclusive final state allows for access to correlations between quark polarization and the angular momentum of final state hadrons through Dihadron Fragmentation Functions (DiFFs). This talk will report on the measurement of the longitudinal beam-spin asymmetry $A_{LU}$ in the production of $\pi^+K^-$, $K^+\pi^-$, and $K^+K^-$ pairs using electron-proton scattering data collected with the CEBAF Large Acceptance Spectrometer (CLAS12). The magnitudes of azimuthal modulations of $A_{LU}$ each correspond to combinations of PDFs and angular momentum states of DiFFs. The measurement of these modulations in the production of dihadrons including kaons, when compared to existing results in charged-pion production, provide insight into the impact of strange quarks and intermediary vector mesons such as $\phi$ and $K^*$ in hadronization. Additionally, we will report on the measurement of $A_{LU}$ in $\pi^0\pi^{+/-}$ production using the same dataset, providing further information on channel-dependence in hadronization.

Speaker: Connor Pecar (Duke University)

cpecar_IWHSSCPHI2024.pdf

61 New measurement of transverse spin effects in hadron production from muon-deuteron semi-inclusive DIS at COMPASS

One of the main objectives of extensive physics program of COMPASS experiment has been to conduct measurements of target-spin asymmetries in semi-inclusive (di-)hadron production in Deep Inelastic Scattering of high-energy muons off polarized targets. In 2022, the latest semi-inclusive DIS measurements were performed using a transversely polarized deuteron target and a 160 GeV/c muon beam. These new measurements complement existing data obtained with transversely polarized proton targets, playing a key role in constraining the d-quark transversity and Sivers functions.
This talk will present initial results based on approximately two-thirds of the newly collected 2022 data.

Speaker: Siranush Asatryan (A.Alikhanyan National Science Laboratory (AM))

Asatryan_IWHSS_24.pdf

Friday Morning: Session 2

62 Phenomenological comparison of Lattice calculations of the Collins-Soper kernel

Relevant information about hadron structure is contained in nonperturbative functions called Transverse Momentum Depentend Parton Distribution Functions (TMD PDFs) and the Collins-Soper kernel, a universal function which regulates their scale evolution.
Usually these functions are obtained by modeling and fitting to experimental data but in recent years lattice calculations have calculated the CS kernel from the theory. These calculations could be advantageous in studying the theory with a less relevant model dependence but they require to be tested too, as they contain internal approximations and assumptions which affect the results.
This talk describes a current study in which we aim to analyze the compatability of recent lattice results with the experimental data.
More specifically the talk focuses on the steps adopted to extract the information from the lattice results and use it, working in the Collins Soper Sterman (CSS) formalism, to fit and directly compare the calculations on low and high energy data.

Speaker: Patrizio Pucci (Charles University (CZ), University of Turin (IT))

Patrizio presentation.pdf

63 Results for Collins and Sivers Asymmetries in K0-Production from 2022 COMPASS Data

We present the preliminary results for the Collins and Sivers amplitudes of the transverse target spin asymmetries (TSAs) in production of neutral kaons ($K^0$) in semi-inclusive deep inelastic scattering. The results were obtained using the data accumulated at COMPASS in 2022 on a transversely polarized $^6$LiD target. The amplitudes were extracted using an unbinned maximum likelihood approach and the kinematic dependences on $x$, $z$ and $p_{T}$ are presented. As a complement to previously measured Collins and Sivers amplitudes for the production of single charged hadrons , these results are a step toward improving our understanding of nucleon structure.

Speaker: Artur Hoghmrtsyan (A.Alikhanyan National Science Laboratory (AM))

K0_Collins_Sivers.pdf

64 Preliminary HERMES results on the beam-spin induced polarization of Lambda and anti-Lambda hyperons produced in semi-inclusive DIS

We present a detailed study of the polarization transfer from a longitudinally polarized lepton beam to the Λ and Λ̄ hyperons produced in semi-inclusive deep-inelastic scattering (SIDIS). The spin-transfer coefficients DLZ and DLZ are extracted using a three-dimensional method, allowing independent measurement of the spin-transfer vector components in the Λ rest frame. The analysis is based on data collected by the HERMES experiment during 1999-2007, covering a wide range of kinematic variables. The preliminary results show that the spin-transfer coefficients are compatible with zero, suggesting a negligible contribution from up quarks that dominate Λ production in the current-fragmentation region for HERMES kinematics. These findings provide new insights into the spin-dependent fragmentation functions and the underlying dynamics of polarized quark fragmentation.

Speaker: Gevorg Nazaryan

SPIN_Transfer_IWHSS_CPHI_2024_Nazaryan.pdf

65 Transverse-Spin Dependent Azimuthal Asymmetries in COMPASS Drell-Yan data

The investigation of Transverse-Spin Dependent Azimuthal Asymmetries in the Drell-Yan process provides a key insight into the spin-dependent structure of nucleons, particularly testing the restricted universality of Transverse-Momentum Dependent Parton Distribution Functions. During the 2015 and 2018 data-taking periods, the COMPASS Collaboration at CERN measured the $\pi^-$p $\rightarrow \mu^+\mu^- X$ reaction, using a 190 GeV/$c$ pion beam and a transversely polarized NH$_3$ target. This analysis examines Transverse Spin Asymmetries in the Drell-Yan process, introducing a new weighting method in which the asymmetries are weighted by powers of the transverse momentum of the dimuon system relative to the beam direction. This approach allows for the direct extraction of specific $k_{\rm T}^2$ moments of the Transverse-Momentum Dependent Parton Distribution Functions. The combined results from these measurements will be presented.

Speaker: Malgorzata Rozalia Niemiec (University of Warsaw (PL))

IWHSS_CPHI_Niemiec.pdf

66 Inverse Kinematics Nucleon Knockout Measurements with a 45 GeV/c Carbon Beam

Investigating the ground-state (g.s.) distributions of nucleons in atomic nuclei remains a key challenge in nuclear physics, often addressed through particle knockout reactions. In 2022, an experiment conducted at JINR utilized a 45 GeV/c carbon-12 beam incident on liquid hydrogen to explore the hard quasi-free 12C(p,2p)11B reaction in inverse kinematics. By tagging the reaction fragments, the experiment effectively suppressed initial and final state interactions (ISI/FSI), enabling an extraction of g.s. properties. We aim to extract the quasi-elastic cross-section and compare the results with previous measurements at lower energies. This contribution presents a discussion of the preliminary results from the experiment.

Speaker: TIMUR ATOVULLAEV

Armenia_Atovullaev_Final.pdf

67 Neutrino-nucleon Neutral Current scattering in the presence of Non-Standard Interaction

Advancements in precise neutrino experiments offer promising opportunities to explore new physics by examining the effects of Neutral Current Non-Standard Interactions between neutrinos and matter. While neutrino oscillation experiments have already imposed stringent limits on all vector NC NSI flavor elements, axial NC NSI remains elusive in these studies. However, neutrino-nucleon scattering presents a unique avenue to investigate axial NC NSI. This discussion focuses on the influence of NC NSI on neutrino-nucleon scattering.

Speaker: Mehran Dehpour (Charles University (CZ))

Mehran-IWHSS-CPHI-2024.pdf

68 Closing

IWHSS-CPHI-2024 - closing.pdf

13:00 Lunch

COMPASS Collaboration Meeting: Session 1

15:00 Coffee break

COMPASS Collaboration Meeting: Session 2