|
November 20, 2025
3:30PM
|
CFNS Seminar: Hadron Polarimetry Systems for the Electron–Ion Collider: Challenges and Solutions
Speaker: Frank Rathmann (BNL)
Location: Stonybrook University - Room C-120
Abstract: The Electron–Ion Collider (EIC) will provide high-luminosity collisions of polarized
electrons with polarized protons and light ions over a broad energy range. To realize
its physics goals, beam polarizations above 70% with relative systematic uncertainties
below 1% are required. Achieving this level of precision demands a modernization of
hadron polarimetry under the EIC’s more challenging beam conditions. This talk presents
the conceptual design and recent progress of absolute and relative polarimetry for
the EIC, building on experience from RHIC and incorporating newly identified requirements
for controlling beam-induced target depolarization in hydrogen-jet (HJET) systems.
For absolute proton polarimetry, next-generation HJET operation at the EIC must mitigate
resonant depolarization driven by the ∼10× higher bunch frequency and increased stored
beam current. Operating at substantially stronger magnetic holding fields (approximately
400mT, compared with 120mT at RHIC), together with azimuthally segmented silicon detectors,
restores three-component polarization sensitivity and suppresses key systematic effects.
Relative polarimetry for fast monitoring will continue to rely on ultrathin carbon
ribbon targets and pC elastic scattering. Dedicated studies of thermal loading, RF
wakefields, and mechanical stress motivate dielectric holders with improved RF shielding
to maintain target integrity and minimize machine impedance under EIC conditions.
Extensions to absolute 3He++ and deuteron polarimetry are underway, leveraging cryogenic
atomic sources and dedicated scattering geometries. Co-location and integration at
IP4 will enable bunchresolved, multi-species operation and cross-calibration between
absolute and relative measurements, establishing a quantitative path to sub-percent
accuracy for polarized hadron beams at the EIC.
|
|
November 6, 2025
3:30PM
|
CFNS Seminar: N-point Energy Correlators and How to Measure them!
Speaker: Rithya Kunnawalkam Elayavalli, Vanderbilt University
Location: Stonybrook University - Room C-120
Abstract: A major goal of high energy collider physics is to quantify the production and evolution
of fundamental particles such as quarks and gluons. What we measure in our detectors
are final state hadrons and photons/leptons that are produced from the metamorphosis
of quarks/gluons into color-neutral objects. In the last few decades, theoretical
frameworks and experimental measurements have advanced with greater detail towards
furthering our understanding of Quantum Chromodynamics at extremes environments such
as the quark-gluon plasma with jet observables. Currently, we are amidst a resurgence
of n-point energy correlators due to its ability to quantity different regimes of
physics within a single observable. A direct analogy is the famous study of n-point
feature space in the cosmic microwave background that allowed us to quantify the different
modes of inhomogeneities within the photon flux in the early universe. In this talk,
we focus on the recent measurements of the 2-point Energy-Energy correlator in both
proton-proton and heavy ion collisions where we observed a remarkable quantification
of potential transition between partonic and hadronic regimes that begs to be studied
differentially. These measurements has now laid the foundation for extracting the
microscopic scale dependent structure of the in heavy ion collisions and lastly, I
will discuss some ongoing work to extend to higher dimensional correlators and phenomenological
studies to understand them.
|
|
October 30, 2025
3:30PM
|
CFNS Seminar: Physics Opportunities near The Neutron Drip Line
Speaker: Shuya Ota (BNL)
Location: Stonybrook University - Room C-120
Abstract:The landscape of the nuclear chart, especially far from stability (exotic isotopes),
has rapidly improved over the last decades thanks to radioactive ion (RI) beam facilities
worldwide. While only about 300 stable isotopes exist, the number of radioactive isotopes
between proton- and neutron driplines amounts to more than 3000. Experiments done
at the RI beam facilities have greatly enhanced our knowledge of properties (mass/binding
energy, matter and charge radius, deformation, energy and spin-parity (Jπ) of bound states and resonances, decay lifetime, and so on) of exotic isotopes. The
new knowledge has taught us that our understanding of nuclear forces combining neutrons
and protons into an atomic nucleus is only valid for stable and long-lived isotopes
near stability. Investigating key exotic isotopes is thus key to completing our understanding
of how an atomic nucleus is formed. FRIB (Facility for Rare Isotope Beams), which
recently started its operation, provides us with opportunities to study exotic isotopes
that have been inaccessible at other RI beam facilities. In the present talk, I will
focus on the physics that we can study near the neutron dripline, where various unpredicted
phenomena emerge in nuclear properties. First, I will present our recently approved
experiment at FRIB, where we plan to constrain nuclear properties of exotic carbon
isotopes (19C) and beyond using the new experimental technique we developed with the less exotic 11Be isotope. Second, I will discuss physics opportunities toward future FRIB PAC, where
more enhanced beam intensities and state-of-the-art detector systems become available,
exploring potential interest from medium/high-energy nuclear physics communities.
|
|
October 16, 2025
3:30PM
|
CFNS Seminar: pion/kaon PDFs
Speaker: Wen-Chen Chang (Institute of Physics, Academia Sinica, Taiwan)
Location: Stonybrook University - Room C-120
Abstract:The pion, as the Goldstone boson of dynamical chiral symmetry breaking of the strong
interaction, is the lightest QCD bound state. Because of its light mass, pion plays
a dominant role in the long-range nucleon-nucleon interaction. Understanding the internal
structure is important to investigate the low-energy, non-perturbative aspects of
QCD. Nevertheless, the uncertainties of parton density functions (PDFs) of pions are
relatively huge, because of the lack of rest pion targets. In this talk, we will review
recent experimental and theoretical progress
on extracting the pion PDFs. Furthermore, we will present quantitative evidence within
the CEM and NRQCD frameworks that existing pion-induced fixed-target J/psi and psi
(2S) data are sensitive to the gluon density of pions and they favor the pion PDFs
with relatively large gluon contents at large x. The recent work of extending the
study to the poorly known kaon PDFs will be discussed. In the final, we will comment
on how the pion/kaon
PDFs could be extracted in the coming U.S. Electron-Ion-Collider (EIC) facility.
|
|
October 15, 2025
3:30PM
|
CFNS Seminar: 3D Imaging of the Pion on a Fine Lattice
Speaker: Jinchen He, BNL
Location: Stonybrook University - Room C-120Recording
Abstract: We present the first lattice QCD calculation of the pion valence-quark transverse-momentum-dependent
parton distribution function (TMDPDF) within the large-momentum effective theory framework.
Using Coulomb-gauge correlators on a fine lattice with momenta up to 3 GeV, we determine
the quasi-TMD beam function, the intrinsic soft function, and the associated Collins–Soper
kernel. Our results show consistency with perturbation theory at short distances and
agree with recent lattice determinations at larger transverse separations. Combining
these ingredients, we obtain the bT-dependent pion TMDPDF and also present results
for the transverse-momentum-dependent wave function of a heavier pion. These findings
provide new insight into hadron structure from first-principles QCD. Slides
|
|
October 2, 2025
3:30PM
|
CFNS Seminar:Effect of TMD Shape function at low transverse momentum in $J/\psi$ photo- and electro-production.
Speaker: Raj Kishore, University of the Basque Country, India
Location: Stonybrook University - Room C-120
Abstract: A proper transverse momentum-dependent (TMD) factorization for quarkonium production
at low transverse momentum necessitates the convolution of the TMD parton distribution
function (TMDPDF) with an additional transverse momentum-dependent function, known
as the TMD shape function (TMDShF). I will present a phenomenological study of the
impact of the TMDShF on quarkonium production in electron-proton collisions, comparing
our results with predictions from the standard non-relativistic QCD (NRQCD) framework.
Our analysis demonstrates that the inclusion of the TMDShF provides a qualitative
explanation for the photo- and electro-production data, particularly at low transverse
momentum, where standard NRQCD predictions fail. Furthermore, we discuss the implications
of a proper treatment of the TMDShF for the extraction of long-distance matrix elements
(LDMEs) in the low-to-intermediate transverse momentum regime
|
|
September 4, 2025
3:30PM
|
CFNS Seminar:Explore the nucleon tomography at the future electron-ion collider
Speaker: Feng Yuan (LBL)
Location: Stonybrook University - Room C-120 Slides
Abstract: Understanding the internal structure of the nucleon and nuclei is of fundamental importance
in subatomic physics. A major focus of research on this topic is the partonic structure
of the nucleon, including its spin and mass structure. In this talk, I will review
recent advances and progress, and emphasize the opportunities at the planned electron-ion
collider (EIC). In particular, the EIC will provide unprecedented precision in exploring
many of the outstanding questions. The talk will focus on one particular aspect, the
nucleon tomography: a three-dimensional imaging of partons in the nucleon.
|
|
August 28, 2025
3:30PM
|
CFNS Seminar: Entanglement entropy, a probe to study hadronization
Speaker: Jaydeep Datta (Stony Brook University)
Location: Stonybrook University - Room C-120
Abstract: Recently, it was discovered that the proton structure at high energies exhibits maximal
entanglement. This leads to a simple relation between the proton’s parton distributions
and the entropy of hadrons produced in high-energy inelastic interactions, that has
been experimentally confirmed. In this Letter, we extend this approach to the production
of jets. Here, the maximal entanglement predicts a relation between the jet fragmentation
function and the entropy of hadrons produced in jet fragmentation. We test this relation
using the ATLAS Collaboration data on jet production at the Large Hadron Collider,
and find a good agreement between the prediction based on maximal entanglement within
the jet and the data. This study represents the first use of quantum entanglement
framework in experimental study of the hadronization process, offering a new perspective
on the transition from perturbative to non-perturbative QCD. Our results open the
door to a more comprehensive understanding of the quantum nature of hadronization.
|
|
August 13, 2025
4:00 PM
|
CFNS Seminar: QCD, ‘tHooft Model and the Light-Front Quark Model
Speaker:Chueng-Ryong Ji (North Carolina State University)
Location: Stonybrook University - Room C-120
Abstract: Interpolating instant and light-front dynamics, I will present a mass gap solution of the 1+1D QCD in the large Nc limit known as the ‘tHooft model to discuss a link between QCD and the Light-Front Quark Model (LFQM). The interpolation between the instant form dynamics and the light-front dynamics will be
highlighted for the study of hadron structures and the utility of the Bakamjian-Thomas construction will be illustrated in the LFQM phenomenology.
|
|
July 16, 2025
4:00PM
|
CFNS Seminar: Theory and Phenomenology of Generalized Parton Distributions
Speaker: Zhite Yu (Jefferson Lab)
Location: Stonybrook University - Room C-120
Abstract:Generalized Parton Distributions (GPDs) are fundamental field-theoretic correlation
functions in QCD that encode tomographic images of partons inside hadrons. In this
talk, I will provide a brief overview of the theory and phenomenology of GPDs, focusing
primarily on the recently developed framework of single-diffractive hard exclusive
processes for connecting GPDs to experimental observables. I will concentrate on the
extraction of GPDs from experimental processes, with particular emphasis on the challenges
and potential solutions related to disentangling different GPDs and determining their x-dependence, both of which are critically important for constructing tomographic images
and matching the x-moments of GPDs to various emergent hadronic properties.
|
|
June 12, 2025
4:00PM
|
CFNS Seminar: Quasinormal modes and hydrodynamics of nonthermal fixed points
Speaker: Michal P. Heller (Ghent University)
Location: Stonybrook University - Room C-133 Slides
Abstract: Nonthermal fixed points are paradigmatic weak coupling far from equilibrium phenomena
associated with self-similarity in time. In the nuclear physics context, they play
an important role in theoretical understanding of thermalization processes in QCD.
I will discuss how adopting the lenses from strongly-coupled systems allows to better
understand how nonthermal fixed point are created. Also, I will use this perspective
to advocate for new physical processes in the vicinity of a nonthermal fixed points
that can be probed in the existing cold atom experiments.
|
