Session C10: Mini-Symposium: Nuclear Effects in Hadronic Physics

Short-Range Correlations and the EMC effects in nuclei

Short-range Correlations (SRCs): pairs of strongly interacting nuclei whose distance is comparable to their radius. Due to their overlapping quark distribution and strong interaction, SRC pairs serve as a bridge between low-energy structure, high-density nuclear matter, and high-energy quark distribution, with important consequences for strong interaction physics and hadronic structure. Recently, experimentalists noted a striking correlation between the slope of the EMC effect and the magnitude of the short-range correlated pair. These two phenomena can both be related to pairs of nucleons in a nucleon strongly interacting and thus have a possible physical reason for being connected to each other. I will highlight key measurements of SRC as well as EMC effects and present upcoming experiments that can provide more insight into the correlations between SRC and EMC effects.   

Di-pion correlations in nuclear DIS using the CLAS detector

The CLAS Collaboration presents a measurement of the nuclear dependence of di-hadron production in deep inelastic scattering off nuclei using the CLAS detector at Jefferson Lab. We report the first measurement of azimuthal correlations in nuclear DIS, and their dependence on kinematic variables such as rapidity separation and the transverse momenta of the two pions. We observe that the distribution of the azimuthal separation between pions peaks at $pi$, but this peak becomes wider and shorter for heavier nuclei compared to deuterium, indicating a "broadening" of the correlations. This represents a new type of study in electron-nucleus collisions and serves as a pathfinder for future experiments with CLAS12 and the Electron-Ion Collider.   

Study of photonuclear reactions in JLab Hall D.

Photonuclear reactions using real photons provide a unique probe for fundamental aspects of QCD in the nuclear medium. The experiment E12- 19-003 was conducted at Jefferson lab in the fall of 2021 using a real photon beam from a 10.9 GeV electron beam on liquid helium, deuterium, and carbon targets using standard GlueX detector configuration. In this experiment, we use photonuclear reactions such as the photoproduction of the rho meson to study the structure of photons, looking for signatures of the transition from hadronic to partonic degrees of freedom. We also search for the signature of a phenomenon predicted by QCD called color transparency. This presentation will provide an overview of the analysis and preliminary results.   

Electron scattering from 12C in the Short-Time approximation

The Short-time approximation, developed in the context of quantum Monte Carlo calculations, allows the calculation of nuclear responses in nuclei with A≥12. It exploits a factorization scheme that consistently retains two-body physics, both in two-body currents and correlations. We will present calculations of response densities and functions in ¹²C in the range of momenta q=300-650 MeV. We will discuss the interpolation scheme used to obtain responses for arbitrary values of q necessary to evaluate cross-sections, and present results for differential cross-sections for electron scattering from ¹²C.   

Applications of the Short-Time Approximation: The Unitary Fermi Gas and Neutrino-Nucleus Scattering

With current and planned neutrino oscillation experiments, it has become increasingly important to develop an accurate theoretical understanding of neutrino-nucleus scattering and exclusive nuclear responses to weak probes. While there are accurate many-body methods to compute quasi-elastic responses to weak probes, they are computationally intensive and limited to the study of the inclusive responses. Recently, the short-time approximation (STA) was developed for the study of nuclear response functions and has been used to compute electromagnetic responses in $Ale 4$ nuclei. This approach, involving a factorization of the response into a two-nucleon component and a spectator system, consistently retains important two-body physics and quantum interference effects while also making possible the study of exclusive response functions. In this talk, I will discuss the theory underpinning the STA and extensions of this work to calculations of the density response in the unitary Fermi gas and the quasi-elastic neutral current response functions in $^2$H with the variational Monte Carlo method.