The Future of Color Transparency and Hadronization Studies at Jefferson Lab and Beyond

Jun 7, 2021, 8:45 AM → Jun 8, 2021, 6:20 PM US/Eastern

Online

Raphaël Dupré (IPN Orsay), Dipangkar Dutta (Mississippi State University), Misak Sargsian (Florida International University), Mark Strikman (Penn State University)

This workshop will explore the options for new theoretical and experimental efforts towards resolving the puzzling lack of color transparency in protons as reported by a new A(e,e’p) experiment  at the recently upgraded Jefferson Lab. The objectives of the workshop are to stimulate new theoretical and experimental work towards understanding the origins of the apparent reaction dependence of this fundamental prediction of QCD, and/or the differences between three-quark and quark-antiquark states.

The connection of color transparency/coherence phenomenon with final state interactions in deep inelastic scattering, hadronization in the nuclear medium, heavy-ion collisions, and quantum entanglement will be examined. The possibility for new experimental searches including at future facilities such as the EIC will also be discussed. The results of the workshop will be summarized in a report that can serve as a roadmap for the future developments and a guide to areas for possible collaboration.

The scientific program is expected to comprise of review talks as well as more focused talks and separate discussion sessions after the presentations. The full agenda is currently under development.

Please mark your calendars, and do not hesitate to contact any of us if you are interested in contributing a talk or participating in the discussions.

The workshop will use Zoom: Meeting ID - 982 7429 3376

Please register for the password

Workshop Poster

Zoom link (please register for password)

Monday, June 7

Session 1: Chair: D. Dutta

1 Opening Remarks

Speaker: Bob McKeown (Jefferson Lab)

BMCK_CT_Jun21.pptx

2 Introduction

Speaker: Dipangkar Dutta (Mississippi State U.)

CT2021_intro.pdf

3 J-PARC hadron physics and future possibilities on color transparency

Speaker: Shunzo Kumano (KEK)

Kumano-JLab-color-trans-2021-06.pdf

4 Chasing QCD Signatures in Nuclei using Color Coherence Phenomena

Speaker: Lamiaa El-Fassi (Mississippi State University)

CTHadron-June21.pdf

10:10 AM break1

Session 2: Chair: R. Dupree

5 Color Transparency: Past, Present and Future

’ll begin by briefly reviewing existing experiments and related theory. The bulk of the talk will be on a new approach, discussed in https://arxiv.org/abs/2104.11168, to the time dependence of putative point-like configurations moving within the nucleus. Those considerations indicate that the Feynman mechanism is responsible for the proton elastic form factor, and that the future of color transparency experiments lies in studies of mesons.

Speaker: Gerald Miller (U. of Washington)

MillerCT2021.pdf

6 Color transparency in JLab experiments using different reaction mechanisms

Observation of color transparency in baryons would provide a new means to study the nuclear strong force and would be the first clear observation of hadrons fluctuating to a small size in the nucleus. This talk will present the recently published Hall C results ruling out observation of the onset of color transparency in baryons up to Q2=14.3 GeV^2. Additionally, an overview of an upcoming photoproduction experiment in Hall D measuring the transparency for various heavy nuclei relative to deuterium is expected to greatly extend the momentum transfer, t, from previous photoproduction measurements and will compare the transparency to predictions with and without the color transparency effect.

Speaker: Holly Szumilla-Vance (JLab)

CT_workshop_2021_slides.pdf

7 The onset of color transparency in holographic light-front QCD

The color transparency of a hadron, propagating without absorption in a nucleus, is a fundamental property of QCD, reflecting the hadron's internal structure and the effective size of its color distribution when it is produced at high transverse momentum $Q$. By using the framework of holographic light-front QCD, one can predict the $Q^2$ behavior of the effective transverse size of the hadronic cross section, its dependence on the hadron's twist $\tau$-- the number of constituent quarks of its valence state -- and the quark current which triggers the initial formation of a small color-singlet configuration which can propagate without interaction in a nucleus. One finds a significant delay in $Q^2$ for the onset of color transparency for hadrons with twist $\tau \ge 3$; this can explain the absence of color transparency for the electroproduction of a proton in the kinematic range of existing experimental tests. Remarkably, the onset in $Q^2$ of color transparency for baryons is predicted to strongly differ for electroproduction events corresponding to the spin-conserving (twist-3) Dirac form factor vs. the spin-flip (twist-4) Pauli form factor.

Speaker: Stanley Brodsky (SLAC)

Color Transparency June 2021 sjb.pdf

Color Transparency June 2021 sjb.pdf

12:00 PM lunch

Session 3: Chair: M. Strikman

8 Hadronization, formation times and CT in quantum-kinetic transport theory

Speaker: Ulrich Mosel (U. of Giessen)

CT_06_21.pdf

9 Transparent Virtual Nucleons and Short-Range Correlations

Speaker: Or Hen (MIT)

CT_Workshop.pdf

10 Transport Estimations of Final State Interaction Effects on Short–range Correlation Studies,

Speaker: Natalie Wright (MIT)

3:00 PM break2

Discussion: 1. Halographic light-front QCD & 2. Virtuality dependence of FSI

Conveners: Eli Piasetzky (2) (Tel Aviv University), Guy de Teramond (1) (U. of Costa Rica)

11 Discussion1: Halographic light-front QCD

Speaker: Guy de Teramond

GdT.Color Transparency Workshop.pdf

12 Discussion2: Virtuality dependence of FSI

Speaker: Eli Piasetzky

Session 4: Chair: M. Sargsian

13 Soft and hard aspects of QCD dynamics in hadronic form factors.

I give an overview of (mostly my own) work on aspects of QCD dynamics in hadronic form factors at large momentum transfer.
The topics include a discussion of basics of soft and hard mechanisms, QCD sum rule applications, calculation of meson form factors in holographic QCD, and connection of form factors to generalized parton distributions.

Speaker: Anatoly Radyushkin (Old Dominion University)

Radyushkin_CTF21.pdf

14 Hadronization studies with CLAS

Speaker: Miguel Arratia (UC Riverside)

Hadronization with CLAS12.pdf

15 Studying Color Transparency through backward pi0 electroproduction off nuclear target

The recent measurements of exclusive backward-angle meson electroproduction
from Jefferson Lab hint at a new domain of applicability of the QCD collinear
factorization framework in the special u-channel kinematics regime. As a
signature of QCD degrees of freedom in nuclei, and as a co-requisite of
reaching the factorization regime, Color Transparency is expected to manifest
itself as an increase in nuclear transparency with increasing momentum
transfer. With the most recent quasi-elastic C(e,e'p) data ruling out Color
Transparency up to Q^2=14.2 (GeV/c)^2, looking for CT in u-channel kinematics
has became a topic of debate within the nuclear physics community. In this
presentation, we present an idea that will attempt to test color transparency
using a u-channel pi0 electroproduction process: A(e,e'p)pi0.

Speakers: Bill Li (William and Mary), Garth Huber (U. of Regina)

pizero_CT_21jun_s.pdf

5:20 PM break3

Discussion: 1. CT and freezing in large p_t two to three high energy processes.

Convener: Mark Strikman (Penn State U.)

16 Discussion3: CT and freezing in large p_t two to three high energy processes.

Speaker: Mark Strikman (Penn State)

commentsct1.pdf

Tuesday, June 8

Session 1: Chair: A. Schmidt

17 Introduction/Recap

Speaker: Dipangkar Dutta (Mississippi State University)

CT2021_intro2.pdf

18 Measuring pion-induced exclusive Drell-Yan process at J-PARC

We propose to measure the pion-induced exclusive Drell-Yan process using the E50 high-resolution spectrometer in the high-momentum beamline of Hadron Hall at J-PARC. The cross sections of this reaction will provide information about the proton generalized parton distributions (GPDs) and the pion distribution amplitudes (DAs) through a timelike approach. The strategies and road maps will be sketched.

Speaker: Wen-chen Chang (Academia Sinica)

CT2021_ExclusiveDY_wchang.pdf

19 CT: factorization theorems vs Feynman mechanism

Speaker: Leonid Frankfurt (Tel Aviv U.)

CT (1).pdf

10:10 AM break 1

Session 2: Chair: L. El-Fassi

20 Hadronization and final-state interactions in nuclear breakup measurements

Speaker: Christian Weiss (JLab)

weiss21_ct.pdf

21 Generalized color transparency in coherent photoproduction of J/psi mesons on nuclei at the LHC

Generalized color transparency (CT) is related to QCD factorization theorems
allowing one to express cross sections of hard processes with nuclei
in terms of nuclear parton distributions. In my talk, I will review
recent studies of generalized CT in coherent photoproduction of
J/psi mesons in ultraperipheral collisions (UPCs) of heavy ions at the LHC
focusing on the leading twist nuclear shadowing of the nuclear gluon
density at small x.

Speaker: Vadim Guzey (Petersburg Nuclear Physics Institute )

guzey_CT_2021.pdf

22 Color transparency studies at intermediate energies in a relativistic Glauber model

I give an overview of work done in the relativistic multiple scattering
Glauber approximation (RMSGA) model. I focus on reactions relevant to
color transparency studies at intermediate energies, such as proton,
pion and rho knockout reactions and discuss the agreement with the world
data.

Speaker: Wim Cosyn (Florida International U.)

Cosyn_CT21.pdf

12:00 PM lunch

Session 3: Chair: H. Szumila-Vance

23 What Can We Learn from Entanglement ?

Speaker: John Ralston (U. of Kansas)

JlabTransparency3.pdf

24 Color transparency in pbar A reactions

Antiproton annihilation on the bound nucleon allows to study exclusive channels
of mesonic interactions with the target residue. If the hard scale is present
then such interactions should be reduced due to the color transparency (CT).
I will discuss, first, the "golden" channel A(pbar,J/psi)(A-1)^*
for the study of the J/psi dissociation cross section on the nucleon.
Then, the d(pbar,pi^- pi^0)p reaction at large c.m. angle will be addressed.
Predictions for PANDA@FAIR at will be given for nuclear transparency ratios
calculated within the generalized eikonal approximation and quantum diffusion model
of CT.

Speaker: Alexie Larionov (JINR Dubna)

larionov_JLAB2021.pdf

25 Jet and heavy flavor production theory at the EIC

Abstract: I will discuss selected topics on jet and heavy flavor production in e+p and e+A
collisions at the future Electron-Ion Collider. In the simpler e+p system I will show how precision
theory of novel energy-energy correlator observables can provide a complementary handle
on the physics of transverse momentum distributions. In e+A reactions I demonstrate the
utility of jet and heavy flavor measurements in constraining the transport properties of large
nuclei and elucidating the physics of hadronization.

Speaker: Ivan Vitev (Los Alamos National Lab)

JetsHeavyFlavorEIC.pdf

3:00 PM break2

Discussion: CT and hadronization studies with the Deuteron

Convener: Misak Sargsian (Florida International University)

26 Discussion 4: Lambda hadronization

Speaker: Lamiaa El-Fassi (Mississippi State U.)

CTHadron-June0821.pdf

27 Discussion 5: CT and hadronization studies with the Deuteron

Speaker: Misak Sargsian (FIU)

MisakSargsian.pdf

Session 4: Chair: W. Cosyn

28 Nucleon re-scattering in D(e,e’p)n : Observations and Possibilities

Speaker: Werner Boeglin (FIU)

29 Nuclear Transparency Measurements in large-angle quasi-elastic A(p,2p) scattering at BNL

We present the results of two experimental programs at the Alternating Gradient Synchrotron of Brookhaven National Lab, to measure the nuclear transparency of nuclei via the quasi-elastic A(p,2p) scattering process near 90° in the pp center of mass. Data was taken at effective incident momenta ranging from 5.0 to 15.8 GeV/c (taking into account the Fermi motion of the target proton in the nucleus), corresponding to 4.8 < Q2 < 12.7 GeV/c2. We discuss the experimental techniques of the two programs, and show our finding that the A(p,2p) nuclear transparency, unlike A(e,e’p) data, is incompatible with a constant value versus energy as predicted by Glauber calculations. We further present the observed scattering angle and A dependence of the data, and describe the possible theoretical explanations of our observed trends.

Speaker: Israel Mardor (Tel Aviv U.)

Mardor NT Ap2p BNL CT Workshop 202106.pdf

30 Color Transparency in Dirty Kinematics

By design, the (e,e’p) color transparency experiments have been done in relatively clean kinematics (parallel) where FSI effects are minimal. Also, the dominator of the transparency is a naïve function such that and one would not expect the ratio to go to unity even if there was color transparency due to initial-state effects, such as short-range correlations, which are neglected. We look into dramatically enhancing any possible color transparency signal, in kinematics accessible to Jefferson Lab 12GeV by going to kinematics where at low Q2 final-state interaction effects are huge and then scanning up in Q2 to observe any possible hint of color transparency. Such kinematics enable us to access the transverse momentum components. This should give us a much greater sensitivity then previous color transparency measurements.

Speaker: Douglas Higinbotham (JLab)

CT-Higinbotham.pptx

5:20 PM break3

Discussion: 1. Suppression of pion field and chiral transparency

Convener: Mark Strikman

31 Discussion 6: Suppression of pion field and chiral transparency

Speaker: Mark Strikman (Penn State)

Closeout