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



Zoom meeting ID: 982 7429 3376 (Please register for the password)
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

  • Abishek Karki
  • Aditya Kulkarni
  • Akihisa Kohama
  • Albert Shahinyan
  • Alexander Somov
  • Alexei Larionov
  • Anatoly Radyushkin
  • Aram Kotzinian
  • Arshak Asaturyan
  • Atsushi Tokiyasu
  • Axel Schmidt
  • Bailing Ma
  • Bappaditya Mondal
  • Bernard Pire
  • Bhesha Devkota
  • Bill Briscoe
  • Bishnu Pandey
  • Carlos Ayerbe Gayoso
  • Carlos Salgado
  • Carlos Yero
  • Catherine Ayuso
  • Christian Weiss
  • Chueng-Ryong Ji
  • Cintia Willemyns
  • Cynthia Keppel
  • David Jenkins
  • David Jenkins
  • Deepak Bhetuwal
  • Dhruvi Saraniya
  • Di-Lun Yang
  • Dipangkar Dutta
  • Douglas Higinbotham
  • Egle Tomasi-Gustafsson
  • Eli Piasetzky
  • Federico Alberto Ceccopieri
  • Garth Huber
  • Gerald Miller
  • Guy F. de Teramond
  • Hamlet Mkrtchyan
  • Harleen Dahiya
  • Hem Bhatt
  • Hiroaki Ohnishi
  • Holly Szumila-Vance
  • Ibuki Terashima
  • Israel Mardor
  • Ivan Vitev
  • Jamal Jalilian-Marian
  • Jan Ryckebusch
  • Jennifer Rittenhouse West
  • John Ralston
  • Joseph Maerovitz
  • Kai Gallmeister
  • Kazuhiro Watanabe
  • Keith Griffioen
  • Kosuke Itabashi
  • Lamiaa El Fassi
  • Lech Szymanowski
  • Leonid Frankfurt
  • Mariana Khachatryan
  • Mark Dalton
  • Mark Jones
  • Mark Strikman
  • Martin Hentschinski
  • Masayasu Hasegawa
  • Michael Wood
  • Michal Krelina
  • Miguel Arratia
  • Misak Sargsian
  • Mitra Shabestari
  • Narinder Kumar
  • Natalie Wright
  • Natalya Dashyan
  • Or Hen
  • Peter Monaghan
  • Phoebe Sharp
  • Rajeev Singh
  • Raphaël Dupré
  • Raza Sufian
  • Robert McKeown
  • Rosi Reed
  • Sabine Jeschonnek
  • Sebouh Paul
  • Shunzo Kumano
  • Stanley Brodsky
  • Stepan Stepanyan
  • Taya Chetry
  • Toshiyuki Morii
  • Ulrich Mosel
  • Vadim Guzey
  • Vardan Tadevosyan
  • Victor Goncalves
  • Vignesh Raj Selvam
  • Volodymyr Aushev
  • Wen-Chen Chang
  • Wenliang Li
  • Werner Boeglin
  • Will Brooks
  • Wim Cosyn
  • Yang-Ting Chien
  • Yasumichi Aoki
Discussion Topics and Material
    • Session 1: Chair: D. Dutta
    • 10:10 AM
    • 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, 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)
      • 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)
      • 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)
    • 12:00 PM
    • Session 3: Chair: M. Strikman
      • 8
        Hadronization, formation times and CT in quantum-kinetic transport theory
        Speaker: Ulrich Mosel (U. of Giessen)
      • 9
        Transparent Virtual Nucleons and Short-Range Correlations
        Speaker: Or Hen (MIT)
      • 10
        Transport Estimations of Final State Interaction Effects on Short–range Correlation Studies,
        Speaker: Natalie Wright (MIT)
    • 3:00 PM
    • 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)
    • 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)
      • 14
        Hadronization studies with CLAS
        Speaker: Miguel Arratia (UC Riverside)
      • 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)
    • 5:20 PM
    • 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)
    • Session 1: Chair: A. Schmidt
      • 17
        Speaker: Dipangkar Dutta (Mississippi State University)
      • 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)
      • 19
        CT: factorization theorems vs Feynman mechanism
        Speaker: Leonid Frankfurt (Tel Aviv U.)
    • 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)
      • 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 )
      • 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

        Speaker: Wim Cosyn (Florida International U.)
    • 12:00 PM
    • Session 3: Chair: H. Szumila-Vance
      • 23
        What Can We Learn from Entanglement ?
        Speaker: John Ralston (U. of Kansas)
      • 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)
      • 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)
    • 3:00 PM
    • 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.)
      • 27
        Discussion 5: CT and hadronization studies with the Deuteron
        Speaker: Misak Sargsian (FIU)
    • 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.)
      • 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)
    • 5:20 PM
    • 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