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...
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...
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...
The nucleon electromagnetic form factors (EMFFs) are among the most basic observables sensitive to the nucleon's internal structure. However, aside from $G_M^p$, high-precision data for the nucleon EMFFs at high-Q$^2$ are scarce due to the challenges associated with such measurements. To address this, the Super BigBite Spectrometer (SBS) collaboration is currently conducting a series of...
Generalized Partons Distributions (GPDs) give a 3-dimensional description of the structure of the nucleon, and give insights into the origin of its spin and the forces at play within it. The study of the Deeply Virtual Compton Scattering (DVCS) reaction with both polarized protons and neutrons is important for the complete extraction of GPDs and of their flavor dependency. Part of the Run...
We will discuss our experimental projects for JLab Hall C to measure novel Compton-like reactions (Timelike Compton Scattering TCS, Double Deeply Virtual Compton Scattering DDVCS) in order to improve our knowledge on Generalized Parton Distributions (GPDs) beyond what is currently accessed from DVCS (Deeply Virtual Compton Scattering). GPDs can lead to interpretation such as tomographic views...
We are currently developing at Virginia Tech a new muon detector aimed at detecting and discriminating muon pairs in exclusive reactions such as Double Deeply Virtual Compton Scattering or J/psi production. We developed a DAQ system and a first prototype system in our lab. In parallel, we are working on simulations to obtain the best design, able to handle high rate and properly separate muons...
Timelike Compton Scattering (TCS) is the timelike equivalent of Deeply Virtual Compton Scattering (DVCS) for which many experiments have been conducted at Jefferson Lab over the past 20 years in order to access Generalized Parton Distributions (GPDs) and information about the 3D structure of the nucleon. TCS is the golden channel to complement DVCS measurements and perform universality studies...
Nuclear and high-energy physics facilities, such as CERN, Jefferson Lab, RHIC, and the forthcoming EIC, are producing exabytes of data. This unprecedented amount of data promises to provide a better understanding of QCD in the nonperturbative regime. However, extracting the required information is an extremely challenging task, as there is no available QCD analytic solution to interpret data....
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...
For the CLAS Collaboration
As part of the efforts to gain more insights into the bound nucleon structure and the associated in-medium modifications that led to the still-to-be-unraveled EMC (European Muon Collaboration) effect, novel approaches can be deployed using, for example, the deeply virtual Compton scattering (DVCS) process to probe the partonic structure of light nuclei, such as 2H...
The ePIC experiment at the upcoming Electron-Ion Collider (EIC) is advancing toward compute-detector integration with seamless data processing from detector readout to analysis. This paradigm shift in data processing is driven by streaming readout and AI technologies.
Streaming readout captures every collision signal, including background events, ensuring no information is lost. This...
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...
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)...
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...
Building a description of nuclear matter valid at arbitrary thermodynamic conditions is a difficult task, even when restricted to the zero temperature limit. In this talk, we will discuss how to build a Neutron Star using three different Equation of State models in their specific range of validity using the MUSES framework: Crust Density Functional Theory valid starting at low densities,...
I will report on our current progress in phenomenological extraction of Generalized Parton Distributions (GPDs) utilizing neural networks and stochastic gradient descent optimization.
In this work, we present updates of the progress towards the first simultaneous extraction of unpolarized collinear and transverse momentum dependent (TMD) parton distribution functions (PDFs) in the proton. The TMD factorization is conveniently formulated in $b_T$-space, which is the Fourier conjugate to the intrinsic transverse momentum of quarks within the proton, $k_T$. In the small-$b_T$...
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...
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...
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...
The study of the three-dimensional (3-D-longitudinal and transverse-momentum) imaging and spin structure of the nucleon emerged from studies of power-suppressed/next-to-leading power (NLP) azimuthal modulation and transverse spin asymmetries in semi-inclusive deep inelastic scattering (SIDIS) experiments. In this talk I will present our latest work on establishing TMD factorization at next to...
Recently, a novel approach has been suggested to compute parton distributions through the use of boosted correlators fixed in the Coulomb gauge from lattice QCD, within the framework of Large-Momentum Effective Theory (LaMET). This approach circumvents the need for Wilson lines, potentially enhancing the efficiency and accuracy of lattice QCD calculations significantly. In this study, we...
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...
