RBRC Workshop: Small-x Physics in the EIC Era

Virtual Event

Virtual Event


Understanding the high energy limit of hadronic and nuclear collisions is at the forefront of nuclear and particle physics. When boosted to ultrahigh energies, all hadrons and nuclei eventually transform into a universal form of matter called the Color Glass Condensate (CGC). The CGC is characterized by the high density (saturation) of small-x gluons which leads to distinct experimental signatures. Tantalizing hints of the CGC have been observed at HERA, RHIC and the LHC, but the definitive evidence is expected to be found at the future Electron-Ion Collider (EIC) at BNL. Indeed, according to the National Science Academy report published in 2019, one of the three major goals of the EIC is to address the nature of the gluon saturation. (The other two are the mass and spin structure of the nucleons.)

With this in mind, the small-x community is gearing up to meet the challenges of the EIC era. Over the past several years, there has been impressive progress in the next-to-leading order (NLO) calculations in the CGC framework of various observables such as single hadron production in proton-nucleus collisions, inclusive and exclusive dijet and trijet production in Deep Inelastic Scattering (DIS), jet-plus-photon production in DIS, etc. We expect that NLO calculations will be the standard tool to confront future experimental data at the EIC.

Another emerging trend of the community is the interplay between small-x physics and spin physics. The RHIC result for the gluon helicity ∆G has underscored the necessity to understand the longitudinal spin structure of the proton at small-x. There have been theoretical indications that a significant fraction of spin and orbital angular momentum is stored in the small-x region. As for the transversely polarized proton, a surprising new connection between the gluon Sivers function at small-x and the QCD Odderon has been pointed out and its implications at the EIC has been discussed.

In view of these developments, we think it is timely to organize a dedicated workshop on small-x physics to summarize the present status of the field and to discuss future directions. A major focus of this workshop will be to identify outstanding problems that could significantly benefit from collaborative efforts amongst scientists working on formal, phenomenological, and computational aspects of small-x physics.

The topics to be covered include:

  • What are the best observables of gluon saturation at the EIC?
  • NLO calculations in the CGC • Interplay between spin and small-x
  • Interplay between spin and small-x
  • TMD, GPD and Wigner distributions at small-x
  • Initial conditions (momentum space, coordinate space, parametrizations beyond MV, ...)
  • Hadronization (MC implementation, coupling to existing event generators, ...)
  • Outstanding open problems at small-x requiring a topical theory collaboration


Event ID:: B000003911

Contact Us
    • 8:55 AM 9:05 AM
      Welcome 10m
      Speakers: Haiyan Gao, Yoshitaka Hatta
    • 9:05 AM 10:35 AM
      Opening session
      Convener: Yuri Kovchegov
    • 10:35 AM 11:00 AM
      Break 25m
    • 11:00 AM 12:30 PM
      Morning session
      Convener: Jamal Jalilian-Marian
      • 11:00 AM
        Theoretical status of small-x resummation 30m
        Speaker: Anna Stasto
      • 11:30 AM
        Global analyses within the small-x resummation collinear approach 30m
        Speaker: Fred Olness
      • 12:00 PM
        Diffractive final states at small x 30m
        Speaker: Heikki Mantysaari
    • 12:30 PM 1:30 PM
      Lunch break 1h
    • 1:30 PM 3:30 PM
      Afternoon session
      Convener: Duff Neill
      • 1:30 PM
        SCET and small-x 30m
        Speaker: Zhongbo Kang
      • 2:00 PM
        Light front methods to compute the initial conditions for small x 30m
        Speaker: Adrian Dumitru
      • 2:30 PM
        Novel lattice methods for computing parton distributions at small x 30m
        Speaker: Xiangdong Ji
      • 3:00 PM
        Lessons and open questions from heavy-ion experiments & small x 30m
        Speaker: Jacquelyn Noronha-Hostler
    • 3:30 PM 4:00 PM
      Break 30m
    • 4:00 PM 5:30 PM
      Open discussion and mini summaries from chairs 1h 30m
      Speakers: Duff Neill, Jamal Jalilian-Marian, Yuri Kovchegov
    • 9:00 AM 10:30 AM
      Morning session 1
      Convener: Andrey Tarasov
    • 10:30 AM 11:00 AM
      Break 30m
    • 11:00 AM 12:00 PM
      Morning session 2
      Convener: Thomas Ullrich
    • 12:00 PM 1:00 PM
      Morning session 3
      Convener: Christophe Royon
      • 12:00 PM
        Capabilities of the ECCE detector proposal for small x physics 30m
        Speaker: Charlotte van Hulse
      • 12:30 PM
        Capabilities of the ATHENA detector proposal for small x physics 30m
        Speaker: Spencer Klein
    • 1:00 PM 2:00 PM
      Lunch break 1h
    • 2:00 PM 3:40 PM
      Afternoon session
      Convener: Alex Kovner
    • 3:40 PM 4:00 PM
      Break 20m
    • 4:00 PM 5:30 PM
      Open discussion and mini summaries from chairs 1h 30m
      Speakers: Alex Kovner, Andrey Tarasov, Christophe Royon, Thomas Ullrich
    • 9:00 AM 11:00 AM
      Morning session
      Convener: Raju Venugopalan
      • 9:00 AM
        Precision study for CGC in forward hadron productions 20m
        Speaker: Bowen Xiao
      • 9:20 AM
        Lessons from the BEST collaboration 20m
        Speaker: Swagato Mukherjee
      • 9:40 AM
        Lessons from the TMD collaboration 20m
        Speaker: Jianwei Qiu
      • 10:00 AM
        Forward dihadron correlation in pA collisions at RHIC 12m
        Speaker: Xiaoxuan Chu
      • 10:12 AM
        Probing gluon number density at Electron Ion Collider 12m
        Speaker: Krzysztof Kutak
      • 10:24 AM
        Pseudo and quasi gluon PDF in the BFKL approximation 12m
        Speaker: Giovanni Chirilli
      • 10:36 AM
        eHIJING event generator for probing small-x gluon in nuclei 12m
        Speaker: Weiyao Ke
      • 10:48 AM
        Dijet impact factor in DIS at NLO 12m
        Speaker: Paul Caucal
    • 11:00 AM 11:20 AM
      Break 20m
    • 11:20 AM 1:20 PM
      Summary and discussions 2h
      Speakers: Astrid Morreale, Bjoern Schenke, Farid Salazar, Yoshitaka Hatta