Bulletin of the American Physical Society
APS April Meeting 2022
Volume 67, Number 6
Saturday–Tuesday, April 9–12, 2022; New York
Session Z07: Hadronic Physics: GeneralRecordings Available
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Sponsoring Units: GHP Chair: Derek Teaney, Stony Brook University Room: Salon 4 |
Tuesday, April 12, 2022 3:45PM - 3:57PM |
Z07.00001: Inter-American Network of Networks of Quantum Chromo-Dynamics Challenges Daniel Tapia Takaki In this talk, we will present the status of the Inter-American Network of Networks of Quantum Chromo-Dynamics Challenges. This AccelNet project will engage the domestic and international network partners around four main goals: (1) develop strategic partnerships across the various nuclear physics research networks in the Americas; (2) identify the needs, strengths and synergies of network partners for developing U.S.-led large scale nuclear science projects; (3) design activities for researchers in the U.S., Canada, and Latin America that will facilitate leveraging complementary resources for quantum chromo-dynamics research, and (4) enhance the training of the next generation of researchers in nuclear physics in a novel set of skills that include international multi-team experience. To enable diverse network opportunities, the research themes will be broad, including research in theory, data analyses, high performance computing, particle detectors and accelerator technologies, real-time event selection, as well as software and Monte Carlo simulation development. Applications of emerging technologies, such as artificial intelligence and quantum technologies, will also be part of the coordination effort. The activities will include scientific retreats, meetings, workshops, and the development of a website to facilitate coordination. The project will also design and carry out exchange and mobility programs between networks in the U.S., Canada and Latin American countries. |
Tuesday, April 12, 2022 3:57PM - 4:09PM |
Z07.00002: Compton Scattering Cross Section Measurement in Hall D at Jefferson Lab Andrew P Smith The PrimEx-Eta fixed-target experiment in Hall D at Jefferson Lab will measure the η→γγ decay width using the Primakoff method with a projected uncertainty of 3.2%. In order to achieve this goal, Compton scattering from the atomic electrons in the target is being used as a reference process. Because of its similar kinematics to the η→γγ decay, the total Compton scattering cross section can be measured using the same experimental configuration as the η decay width measurement. Thus, it can be used to verify the systematic uncertainties for the η decay width measurement and monitor the luminosity, detection efficiency, and overall experimental stability. The data taking of the first two phases of the PrimEx-Eta experiment were completed in Spring 2019 and Fall 2021, with the majority of the data being collected on a liquid 4He target. In this talk, I will discuss the preliminary results for the total Compton scattering cross section measured on both the liquid 4He target, as well as a solid 9Be target. Our result will offer the first measurement on this fundamental QED process with a beam energy up to 10 GeV. I will also present the systematic uncertainties associated with this cross section measurement and discuss how it will be utilized in the η meson decay width measurement. |
Tuesday, April 12, 2022 4:09PM - 4:21PM |
Z07.00003: Single π0 Photoproduction off the Deuteron William Briscoe, Igor I Strakovsky The γn→π0n cross section (W = 1195 - 1533 MeV) [1] and beam asymmetry (W = 1271 - 1424 MeV) [2] has been measured for the first time. The data were collected in the A2 Hall of the MAMI tagged photon beam facility with the Crystal Ball and TAPS calorimeters covering pion CM angles 18 -162 degrees and from 49 to 148 degrees. The extracted values of cross sections and asymmetries have been compared to predictions based on PWAs of the existing pion-photoproduction database. We include the SAID, MAID, and Bonn-Gatchina analyses; while a revised SAID fit, including the new A2 measurements, has also been performed. Selected photon-decay amplitudes N*→γn at the resonance poles are determined for the first time. |
Tuesday, April 12, 2022 4:21PM - 4:33PM |
Z07.00004: CLAS12 Charged Two-Pion Electroproduction Off the Proton Krishna C Neupane The study of the structure of excited states of the nucleon is one of the major fields to investigate the strong interaction dynamics that underlie baryon generation from quarks and gluons. CLAS in Hall B at Jefferson Lab has already produced the dominant part of the available world data on charged double-pion electroproduction in the nucleon resonance region for photon virtualities, Q2, up to 5 GeV2. These data have allowed us to obtain the resonance electroexcitation amplitudes for most excited states in the mass range up to 1.8 GeV. This talk will focus on acceptance-corrected yields, single-particle-detection efficiency, and other preliminary results of one of the first CLAS12 measurements, with CLAS12 being the only available detector in the world capable of exploring resonance electroexcitation amplitudes in the still almost uncharted range of Q2 > 5.0 GeV2. The charged double-pion channel offers a unique opportunity to explore the evolution of the resonance structure at the distances where the transition from quark-gluon confinement to pQCD regime is expected. |
Tuesday, April 12, 2022 4:33PM - 4:45PM |
Z07.00005: Flavour SU(3) symmetry-breaking as a constraint on the strange quark condensate Jason N Ho, Tom G Steele, Derek Harnett While the light quark vacuum condensate $\langle \bar{q} q\rangle$ is well-understood and known to good precision, the strange quark vacuum condensate $\langle \bar{s} s\rangle$ is not as well determined. Using the renormalization-group invariant strange quark mass ratio $r_m = m_s/m_q$, as well as properties of pions and kaons, we develop a simple constraint on a dimensionless PCAC deviation parameter $r_p$ and the quark condensate ratio $r_c = \langle \bar{s}s\rangle/\langle \bar{u}u\rangle$ to ensure self-consistency between the two parameters, and to tighten the bounds on $r_p$. We compare predictions in the literature against this constraint. |
Tuesday, April 12, 2022 4:45PM - 4:57PM |
Z07.00006: "Observables for electro-scattering on targets with any spin" Frank Vera, Wim Cosyn Starting from the Weinberg formalism for the construction of fields for any spin, we propose an algorithm for the construction of the independent operators that enter the scattering amplitude associated with electromagnetic observables. This procedure is useful for the systematic study of the structure of hadrons and nuclei. In particular, it is very convenient in the case of spin-dependent observables. Since new features appear in the hadronic structure of higher spin targets, the investigation of their properties can improve our understanding of the strong force. As a proof of principle, we apply this method to the description of elastic electron-deuteron scattering. The result of calculations within Instant and Light-Front forms of dynamics is presented for the vector and axial electromagnetic form factors and is compared with the existing literature. We discuss potential extensions of the formalism to hard exclusive processes on the deuteron. |
Tuesday, April 12, 2022 4:57PM - 5:09PM |
Z07.00007: Production and polarization of prompt J/ψ to O(α_s^3) in the improved color evaporation model Vincent Cheung, Ramona L Vogt 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 recent results of quarkonium polarization in the improved color evaporation model (ICEM), and how feed down from higher states affect the polarization in this approach. |
Tuesday, April 12, 2022 5:09PM - 5:21PM |
Z07.00008: Quark Entanglement in the Proton on the Light Front Eric Kolbusz, Adrian Dumitru We consider entanglement of quarks in the proton on the light |
Tuesday, April 12, 2022 5:21PM - 5:33PM |
Z07.00009: Is overlapping double gluon bremsstrahlung in a quark-gluon plasma accurately described by the Ncolor = ∞ limit? Omar Elgedawy, Peter B Arnold Jets produced from colliding two heavy nuclei play an important role in understanding properties of the Quark Gluon Plasma. During their travel through the medium, high energy partons lose energy through splitting processes like bremsstrahlung and pair production, induced by elastic scatterings with the medium. In the high energy limit, these splitting processes are coherent over large distances and the underlying elastic scatterings can no longer be treated as quantum mechanically independent, leading to a suppression of the splitting rate known as the Landau-Pomeranchuk-Migdal effect. An important question is whether consecutive splittings are themselves quantum mechanically independent or instead overlap significantly. Previously, the overlap of splitting rates has been analyzed in the Nc = ∞ limit within the thick medium approximation. To see if such Nc = ∞ calculations apply to real QCD with Nc = 3, we calculate the next-to-leading order correction in 1/Nc to overlapping gluon double-splitting. I will report first results on whether the Nc = ∞ approximation to the differential rate of overlapping double bremsstrahlung of gluons is reliable, and in particular whether the correction is large or small compared to the naive expectation of 1/Nc2 ∽ 10% for Nc = 3. |
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