Session GC: Hadronic Physics III

The Tagged Deep Inelastic Scattering experiment at JLab

The Tagged Deep Inelastic Scattering (TDIS) experiment in Hall A at the Jefferson Laboratory is an ambitious experiment making use of a new multiple time projection chamber in conjunction with the Super Bigbite Spectrometer (SBS) to study the internal structure of hadrons. The experiment was originally designed  to measure the structure functions (SFs) of pions through the Sullivan process (electron scattering off of the nucleon meson cloud), making use of the tagging technique (measuring one or more of the recoil nucleons in coincidence with the scattered electron). Two run groups have been added to the original proposal. First is the novel measurement of the kaon SF, and the second is a comprehensive measurement of the neutron SFs in the valence and resonance regions, the neutron magnetic form factor, and the Deuterium EMC effect.

This talk will present the motivation and the current status of the experiment.   

Quirks of QCD: Twist-2 Operators on the Lattice

In deep inelastic scattering (DIS) probes of hadronic structure, we approximate the matrix elements of the electromagnetic currents using the operator product expansion. The operators are ordered by their twist (dimension minus spin), with twist-2 being the leading order. We would like to perform such calculations on a discrete, Euclidean lattice, as this offers us access to the nonperturbative region on quantum chromodynamics; however, on the lattice, these operators experience power divergent mixing, diverging as we take the lattice spacing to zero. We aim to control this mixing by incorporating the gradient flow, a gauge-invariant Gaussian smearing of the gauge fields that removes ultraviolet fluctuations in those fields. We study an example in perturbation theory.   

Kinematic reconstruction for inclusive reactions at the Electron-Ion Collider

One of the primary physics goals of the future electron-ion collider (EIC) is understanding the quark structure and spin origin of nucleons. Inclusive deep inelastic scattering (DIS) reactions play a pivotal role in these studies, through measurements of inclusive cross sections and double-spin asymmetries. Inclusive DIS measurements rely on fundamental aspects of detector performance, such as electron identification and kinematic reconstruction resolution, that are foundational to more complex analyses. The EIC project detector (Detector 1), centered on reuse of the BaBar 1.4 Tesla superconducting solenoid, has demonstrated that it meets the key performance criteria for carrying out such measurements. This talk will summarize the kinematic resolution expected at the EIC based on full GEANT4 simulations of Detector 1, including standard and novel kinematic reconstruction methods.   

Neutron Magnetic Form Factor Measurement at High Q2 with CLAS12

Understanding the internal structure of the nucleon is one of the central goals of nuclear and high-energy physics programs at Jefferson Lab. The basic observables that provide valuable insight into this structure are the elastic electromagnetic form factors, G_E^p, G_M^p, G_Eⁿ, and G_Mⁿ, at high Q². In this talk, we will focus on the measurement of neutron magnetic form factor, G_Mⁿ, at high Q2 using the CLAS12 detector. The ratio method of quasi-elastic e-n to e-p scattering on a deuteron target is used to extract G_Mⁿ. The advantage of using the ratio method is to reduce the impact of systematic uncertainties like luminosity, etc. This method requires a precise measurement of neutron detection efficiency (NDE). In this talk, we will discuss the procedures that we have used to measure the ratio and show preliminary results for the CLAS12 NDE.   

Neutron Elastic Form Factor Ratio from Recoil Polarization

The GEn-RP experiment is among various form factor experiments with the Super-Bigbite Spectrometer setup at Hall-A, Jefferson Lab and measures the ratio of electric to magnetic elastic form factors of the neutron, GEn/GMn using two recoil polarimetry techniques at Q² = 4.5 (GeV/c)² in quasi-elastic electron-neutron scattering from a deuterium target.

The ratio of the above-mentioned form factors is measured from the ratio of the transverse (P_x) and the longitudinal (P_z) components of the spin polarization, that is transferred to the recoiling neutron from an incident, longitudinally polarized electron beam. Both low-momentum, large-angle protons produced during np → np elastic scattering and high-momentum, small-angle protons produced by np → pn (charge exchange) are used to analyze the neutron polarization components upon precessing through a known magnetic field.

This experiment will yield GEn /GMn at the highest Q² kinematic point yet recorded and the experimental figure-of-merit information on the polarimetry along with the analyzing powers will be used to optimize future measurements of GEn/GMn to reach higher Q² values using recoil polarimetry techniques.

    

Poloarization Measurement of Photoproduced Hyperon Pairs at GlueX.

We have studied the spin structure of photoproduced hyperon pairs for the first time. At Jefferson Lab, we have accumulated data of the reactions γp→ Λ anti-Λ p (with Λ→π^-p, anti-Λ→π⁺anti-p ) from threshold up to a beam photon energy of 11.4 GeV. Phenomenological Monte Carlo models have been developed to identify various mechanisms producing anti-Λ Λ and anti-Λ p systems according to the momentum and angular distributions. Preliminary hyperon polarization measurements in several coordinate systems, as well as a spin correlation study of the hyperon pairs from GlueX Phase-I period will be presented. These results, along with the differential cross section measurements presented, promise to give a better insight into the role strangeness plays in the dynamics of the photoproduced baryonic systems.    

Observables for quark and gluon transverse orbital angular momentum

I will present twist-three observables from deeply virtual exclusive scattering experiments constraining both the quark and gluon transverse orbital angular momentum. The latter will be confronted with a calculation of the generalized transverse momentum distribution k_T² moment using a diquark model. The calculation includes the evaluation of the quark-gluon-quark term giving rise to gluonic pole contributions in both single spin asymmetry (SSA) and double spin asymmetry (DSA) measurements. Similarities with the occurrence of gluonic poles in the Sivers function will be discussed.   

Studying hadronization in the nuclear medium with heavy flavor production at the future Electron Ion Collider

Heavy flavor quark production in energetic electron-proton and electron-nucleus collisions at the future Electron Ion Collider (EIC) offers a unique sensitivity to study the gluon dynamics inside the nucleon and nucleus. Measuring heavy flavor hadron production in such collision systems can also provide insights into the hadron formation mechanism and color transport inside cold nuclear matter.

Precision heavy flavor measurements require good momentum and pointing resolution, which is fulfilled by a Monolithic Active Pixel Sensor (MAPS) based inner tracking and vertexing systems in the proposed EIC experiment. With the realistic detector effects and expected integrated luminosity for EIC, we reconstructed D^{0} mesons and \Lambda_{c} baryons via their decay products and calculated the projected statistical uncertainties. In this talk, we will present the projected precision of the charm hadron multiplicities measurements on nucleus A relative to proton with fully reconstructed D^{0} and \Lambda_{c}. We will discuss its impact on understanding charm hadronization in the nuclear matter the discriminating power on different hadronization models.   

Statistical Hadronization Model Calculations of Charm Hadron Production in Relativistic Heavy Ion Collisions at the LHC

The validity of the Statistical Hadronization Model (SHM) has been successfully tested toadequately reproduce hadronic particle abundances of light flavored hadrons to over nine orders of magnitude in high energy collisions of heavy ions. Heavy flavor particle production is of particular interest in heavy ion phenomenology due to the

large difference between the mass of the bare heavy quarks and the calculated pseudocritical hadronization temperature. Because of their large masses, heavy quarks are produced in the initial hard partonic scattering of heavy ion collisions. The produced charm quarks then interact with the collision fireball and eventually thermalize. These thermalized charm quarks can then recombine with the surplus of deconfined light flavor quarks in the medium generated in a heavy ion collision; where the number of available charm quarks is assumed to stay constant until hadronization is reached. This thermal-like behavior of final state charm yields allows for their production to be modeled in the context of the SHM with an additional charm fugacity parameter. In this contribution, I will show comparisons of my recent thermal model calculations of single charm hadrons measured in PbPb Collisions at $\sqrt{s_{NN}}$ = 5.02 TeV at the LHC via the Thermal-FIST Hadron Resonance Gas model package. I will additionally show thermal model predictions of multi-charm baryon yields expected to be measured by ALICE in the upcoming Run 3 of the LHC.