The structure of the $\Lambda(1405)$ resonance has challenged hadron physicists for more than forty years. Its structure is controversially debated as either: an antikaon-nucleon bound state, a dynamically generated baryon resembling a meson-baryon molecule, or a resonance with $\pi\Sigma$ and $\bar{K}N$ poles. Experimental results vary in line shape and peak position, depending on reaction...
At high energy, the fundamental description of matter (Quantum Chromodynamics or QCD) is currently only directly applicable to specific regimes, leaving large portions of the QCD phase diagram uncharted, especially around the regime relevant for neutron stars. To bridge different regimes, the MUSES collaboration has built a cyberinfrastructure that provides descriptions of matter based on...
We will address various aspects of the very rich chiral and partonic structure of strongly interacting systems such as the nucleon. One example are the (generalized) polarizabilities of the nucleon, which are largely governed by chiral dynamics. As far as the partonic structure of the nucleon is concerned, we will cover the non-trivial universality of transverse-momentum dependent...
Since baryon is a composite particle, one may wonder which degrees of freedom are carrying the conserved charges, including the baryon number. A baryon junction, that arises naturally in a gauge-invariant description of the baryon wavefunction, is a perfect candidate to associate the baryon number with. In this talk I will discuss various possibilities to test the flow of baryon number...
We present a comprehensive study of bottomonium ($\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$) suppression in minimum-bias proton-Lead ($p$-Pb) collisions at 5.02 and 8.16 TeV. Our approach accounts for both cold nuclear matter (CNM) effects (nuclear parton distribution function (nPDF) effects, coherent energy loss and momentum broadening), and hot nuclear matter (HNM) effect due to the...
Multiple approaches attempt to describe hard and semi-hard scattering processes in p+A-style collisions. One approach is based on leading-twist pQCD in a collinear factorization picture, where all initial and final state effects on hard processes are included within a set of nuclear parton density functions (nPDFs) universal in x and Q^2. Other approaches are based on a dynamical description...
In the Color Glass Condensate (CGC) framework and using the formalism of the light-cone wave function (LCWF), we calculate the differential cross-section for inclusive gluon production at next-to-leading order at central rapidity. In the CGC, the LCWF consists of two components: the soft and valence contributions residing in the corresponding Hilbert spaces. The scale of the separation between...
Understanding the origin of the proton's mass is a fundamental question in nuclear physics. The proton’s three valence quarks account for only a small fraction of its total mass, with the majority arising from the strong force, mediated by gluons.
Recent experiments studying near-threshold J/ψ production at Jefferson Lab have provided new insights into the proton's mass distribution. I will...
Studying the in-medium stimulated effects entails improving the experimental methods to probe the confinement dynamics of quarks and gluons, the building blocks of atomic nuclei. Therefore, the deeper one looks, the more perplexing the strongly interacting particles, namely hadrons, behave. Unraveling this behavior, as described by quantum chromodynamics (QCD), the theory of strong...
Directed flow of particles is an important feature seen in heavy-ion collisions and is a
sensitive probe of the equation of state (EoS) of the matter produced in the collisions.
Model calculations have also predicted that directed flow could be a sensitive probe of the
softening of the EoS associated with a first order phase transition. Directed flow of protons
and anti-protons are also of...
The Electron-Ion Collider (EIC) at the Brookhaven National Laboratory is a versatile machine which is designed to address some of the most profound questions about the properties of nuclear matter. To unravel the rich structure of hadrons the EIC will provide the precise imaging of the dense QCD medium inside protons and nuclei. However, understanding of the hadron structure is not possible...
Nuclear spectroscopy with heavy ion beams and fixed targets has emerged as a powerful tool for studying sub-atomic nuclei with strangeness, known as hypernuclei. Recent experiments using high-energy heavy ion beams have challenged the current understanding of light hypernuclei [1,2,3,4,5,6,7,8], particularly the hypertriton which is a subject of ongoing debate in the field, often referred to...
Ultrarelativistic isobar collisions serve as a powerful tool for probing nuclear structures. These high-energy collisions are typically described by a hydrodynamic expansion, preceded by a pre-thermal equilibrium phase. However, due to the computational complexity of hydrodynamic simulations, studies of isobar nuclear structures often rely on geometrical estimators, such as eccentricities,...
A significant open question is how to bridge two disparate regimes of QCD: the high $Q^2$ regime, where perturbative QCD describes the behavior of quarks and gluons very well, and the low $Q^2$ regime, where effective theories such as Chiral Perturbation Theory are most successful at describing partonic structure. One way to study the transition between these regions is with the use of nucleon...
This talk presents the first measurement of low-transverse-momentum ($p_T$) charged-hadron distributions in pseudorapidity and azimuthal angle, relative to the momentum direction of $Z$ bosons, in lead-lead ($\mathrm{PbPb}$) collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s_\mathrm{NN}} = 5.02$ TeV. The analysis uses PbPb data from 2018 with an integrated luminosity of $1.67...
Uncertainty quantification (UQ) plays a crucial role in the predictive power of nonperturbative quantum correlation functions at high precision. My research explores new approaches to UQ in the context of parton distribution functions (PDFs), using machine learning techniques to map between observables and underlying theoretical models, and navigate the complex parametric landscape of...
Artificial intelligence and machine learning techniques have gained increasing attention in recent years as powerful tools for advancing data analysis and simulations across various fields of physics. Among these, generative models are notable for their ability to create complex data distributions, with Generative Adversarial Networks (GANs) already showing promise in reducing the...
A new global QCD analysis by the JAM collaboration performs the first extraction of transversity PDFs and tensor charges using both the Transverse Momentum Distribution (TMD) and Dihadron Fragmentation Function (DiFF) channels simultaneously, including all currently available experimental data. Known theoretical constraints on transversity, namely, its small-$x$ asymptotic behavior and the...
SpinQuest is the Fermilab fixed-target Drell-Yan (DY) experiment that aims to measure the sea-quark Sivers functions by impinging a 120 GeV unpolarized proton beam on transversely polarized ammonia, NH$_3$, and deuterated ammonia, ND$_3$, targets. In this measurement, the DY process also offers clean access to the transversity distribution, $h_1(x)$, quantifying the probability of scattering...
In this talk, I will report some recent progress in extracting the gluonic gravitational form factors (GFFs) from near threshold heavy quarkonium productions. Particularly, I will discuss the effect of the next-to-leading order (NLO) corrections on the extraction of the GFFs, where the singlet quark contribution will also emerge. With the NLO corrections, I will remark on the theoretical...
The GlueX experiment at Jefferson Lab has collected a world-leading set of photoproduction data, which is being used to address many outstanding problems in hadronic physics. I will present the status of the search for hybrid mesons with GlueX data, including recent results on polarization observables and partial wave analyses. I will also discuss a selection of other recent results,...
The Relativistic Heavy Ion Collider (RHIC) has been in operation since 2001, contributing significantly to the study of strong interactions and nuclear matter under extreme conditions. The PHENIX experiment, operated from 2001 to 2016, has collected a comprehensive dataset that continues to yield impactful results with heavy flavor probes. These measurements have provided critical insights...
Relativistic heavy-ion collisions produce loosely bound hadronic molecules at a rate that is surprising large, since the molecules seem to emerge from a hadron gas whose temperature is orders of magnitude larger than their binding energies. These molecules have been referred to as "snowballs in hell". Their production has been explained in terms of a novel thermodynamic variable conjugate to...
The system of η and η′ offers a flavor-conserving laboratory to test the low-energy QCD and to search for new physics Beyond the Standard Model. The symmetry properties of QCD at low-energy, such as the chiral symmetry or the axial anomalies, are manifested in the decays of η and η′. Thus, a study of η/η′ will yield light on our understanding of the origin and the dynamics of QCD...
The transverse single-spin asymmetry (TSSA) measures the asymmetry in particle production relative to the plane defined by the transverse spin axis and the momentum direction of a polarized hadron. TSSAs have emerged as a powerful tool for exploring Quantum Chromodynamics (QCD), offering insights into the dynamics of initial-state hadrons and the hadronization process. In J/ψ production, which...
The nucleon spin structure is an important aspect of hadronic physics, and spin sum rules have been extensively used to study it. We will report on the latest experimental results published on nucleon spin sum rules. The data were taken at Jefferson Lab in Hall A and B by experiments E97-110 and EG4, respectively. They covered the very low $Q^2$ domain, down to $Q^2 \sim 0.02$ GeV$^2$, Chiral...
Measuring parton distribution functions (PDFs) in the valence region at high Bjorken-x is one pillar of the experimental program of Jefferson Lab at 12 GeV. In this talk, I will review the status of our knowledge of polarized and unpolarized nucleon structure functions at very high x. I will especially focus on the recent “BONuS12” experiment with CLAS12 at Jefferson lab to measure the...
The proposed Electron-Ion Collider (EIC) will utilize high-luminosity high-energy electron+proton ($e+p$) and electron+nucleus ($e+A$) collisions at different center of mass energies to solve several fundamental questions in the nuclear physics field. Due to their high masses ($M_{c,b} > \Lambda_{QCD}$), heavy quarks are produced early in hard partonic scatterings and their flavors are...
I will report on our current progress in phenomenological extraction of Generalized Parton Distributions (GPDs) utilizing neural networks and stochastic gradient descent optimization.
Understanding the confinement dynamics of quarks and gluons, the building blocks of atomic nuclei, remains a prime challenge in modern subatomic physics.~This investigation could be carried out by studying hadronization processes, particularly in the nuclear medium, where medium-stimulated effects such as hadron attenuation and transverse momentum broadening can be probed, providing critical...
The shapes of colliding nuclei influence flow patterns in heavy-ion collisions due to hydrodynamic responses to collision geometry. We performed simulations to study the impact of nuclear structure on anisotropic flow ratios in Pb+Pb and Xe+Xe collisions at the LHC. Our findings show these ratios are significantly affected by nuclear structure, offering a new method to probe deformed nuclear...
Currently, the nature of the baryon number carrier remains debated. Although it is conventionally assumed to be carried by quarks, an alternative model suggests that the baryon number is instead carried by a Y-shaped gluon configuration called the baryon junction. This has significant ramifications for baryon emission at mid-rapidity in nuclear collisions. In this work, we accurately extract...
One of the best ways to understand hadronization in QCD is to study the production of quarkonium. The color evaporation model (CEM) and Nonrelativistic QCD (NRQCD) can describe production yields rather well but spin-related measurements like the polarization are stronger tests. In this talk, we will present the first expansion of the improved CEM into electron-proton collisions, and the...
Understanding the dynamics of QCD at high energy or small Bjorken x is crucial for describing gluon saturation and non-linear interactions within hadronic wave functions. This regime, characterized by high gluon densities, pushes QCD into a dense domain where standard techniques are insufficient. Evolution equations like the JIMWLK equation capture this behavior. While the leading-order (LO)...
Double parton scattering in p+p and p+A collisions is described by double parton distribution functions (dPDFs), a joint distribution over two partons. dPDFs differ from a product of single-parton distribution functions (PDF) since they encode parton correlations. We compute the double quark density matrix and dPDF from a simple three-quark model proton light-cone wave function. We then...
The first excited state of the nucleon dominates many nuclear phenomena at energies above the pion-production threshold and plays a prominent role in the physics of the strong interaction. The study of the N to $\Delta$ transition form factors (TFFs) allows to shed light on key aspects of the nucleonic structure that are essential for the complete understanding of the nucleon dynamics. In this...
We present recent results and future outlook for gluon parton distributions from lattice QCD, focusing primarily on the pion and nucleon gluon parton distribution functions (PDFs). The nucleon gluon PDF is a crucial input to the prediction of rare physics processes such as Higgs and $J/\psi$ production and beyond the standard model physics. The pion gluon PDF is expected to hold clues about...
In this talk, I will provide an overview of recent theoretical developments in understanding the three-dimensional momentum-space structure of hadrons.
Transverse Momentum Distributions (TMDs) are essential for describing processes like semi-inclusive deep inelastic scattering (SIDIS), Drell-Yan production, and hadron-hadron collisions at low transverse momentum, where transverse...
In this talk, we will present the recent results from the Relativistic Heavy Ion Collider Beam Energy Scan II, with a special focus on the exploration of the QCD phase structure.
We describe numerical simulations of stochastic fluid dynamics near a critical point in the Ising universality class. This theory is known as model H, and is expected to govern universal dynamics in the vicinity of a possible critical endpoint in the QCD phase diagram. We verify dynamic scaling near the critical point of a two and three-dimensional fluid and extract the associated critical...
We expand upon small-$x$ helicity phenomenology by using the small-$x$ helicity evolution equations in a global analysis that now incorporates polarized proton-proton ($pp$) data in addition to the previously analyzed deep-inelastic scattering (DIS) and semi-inclusive DIS (SIDIS) data, all at $x < 0.1$. We specifically analyze the double longitudinal spin asymmetry in single-inclusive jet...
Over the last two decades, the PHENIX experiment has utilized the polarized proton collisions delivered at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory to study spin structure and dynamics in high energy nuclear physics. Measurements of longitudinal spin asymmetries in direct photons and light mesons revealed the important contribution of gluon polarization to...
SpinQuest is the Fermilab's high-luminosity Drell-Yan experiment that aims to explore the interaction of 120 GeV proton beam with transversely polarized ammonia (NH$_3$), and deuterated ammonia (ND$_3$) targets to probe the Sivers functions of light quark flavors in the nucleon sea. A non-vanishing sea quark Sivers functions provide evidence of their orbital angular momentum, which would...
In the aftermath of a high energy non-central heavy-ion collision, it is expected that along a quark-gluon plasma (QGP) a very strong electromagnetic field is produced. To characterize the strength of such a field, it has been theorized that it can induce measurable effects on the width and leptonic invariant mass of the Z-boson, with the effect being maximal for semi-central collisions. We...
Exclusive vector-meson production in e+A collisions has been suggested as a probe to analyze the distribution of gluons within the nucleus. However, the Good-Walker paradigm implies that coherent exclusive events probe the spatial distribution of the nucleons, whereas incoherent exclusive interactions are sensitive to event-by-event fluctuations within the nucleus. Consequently, any photons...
The Continuous Electron Beam Accelerator Facility, CEBAF, at the Thomas Jefferson National Accelerator Facility has been conducting world class nuclear physics experiments for nearly thirty years. I will give an overview of the current experimental program as well as an overview of the machines tentative schedule for the next several years. I will also present possible future machine...
The emergence and evolution of collective behavior in small collision systems remains a key area of interest in high-energy nuclear physics. To understand how collectivity evolves with system size RHIC has conducted a dedicated small system scans, including He$^3$+Au, d+Au, and p+Au collisions.
In 2021, the STAR collaboration expanded the scan by introducing a symmetric yet small system...
The dominant interaction between a heavy quark and antiquark at low energy is described through the static potential. The real part of the potential becomes screened with a screening mass proportional to the temperature, and the imaginary part of the potential gives bound-states a non-zero width. As the temperature increases bound-states can disappear either because they are not supported by...
Hadronic resonances are emergent phenomena of Quantum Chromodynamics at intermediate energies. Almost all resonances decay not only to two, but also to three or more particles. Parametrizing three-body dynamics in terms of unitary coupled-channel amplitudes is, therefore, a prerequisite for the extraction of resonances from experiment and also from finite-volume lattice QCD spectra. In the...
We report a lattice calculation of $x$-dependent valence pion generalized parton distributions (GPDs) at zero skewness with multiple values of the momentum transfer $-t$. The calculations are based on an $N_f=2+1$ gauge ensemble of highly improved staggered quarks with Wilson-Clover valence fermion. The lattice spacing is 0.04 fm, and the pion valence mass is tuned to be 300 MeV. We determine...
High-energy collisions between unpolarized electrons and nucleons allow for the probing of the internal structure of nucleons (protons and neutrons). This can be accomplished through the use of inclusive deep inelastic scattering (DIS), where only the scattered electron is detected, or semi-inclusive deep inelastic scattering (SIDIS), where also another final-state particle is detected. If the...
In this talk, we will summarize the goals of the workshop held at Stony Brook University (CFNS) in January 2025, which focused on advancing our understanding of cold nuclear matter (CNM) effects in hadron-nucleus (h+A) collisions. We will explore the challenges of applying perturbative Quantum Chromodynamics (pQCD) to h+A collisions, particularly the complexities arising from CNM effects such...
Critical points are categorized based on the number of relevant variables. The standard critical point in systems like the Ising model involves two relevant variables, namely temperature and external magnetic field. In contrast, a tricritical point is characterized by four such variables. The protocritical point, widely known as the Yang-Lee edge singularity (YLE), is the simplest form of...
