Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session Z15: QCD and Hadron PhysicsLive
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Sponsoring Units: GHP Chair: Dave Gaskell, Jefferson Lab |
Tuesday, April 20, 2021 3:45PM - 3:57PM Live |
Z15.00001: Study of Current and Target Fragmentation using $\Lambda$ Electroproduction off Nuclei Taya Chetry The hadronization or fragmentation, where a struck quark transforms into color-neutral hadrons, is an effective tool to probe the confinement dynamics as well as the characteristic time-scales involved in the process. These time-scales elucidate our understanding of the color-neutralization and the subsequent non-perturbative formation of the observed hadrons. This talk will report the first-ever analysis of the semi-inclusive deep inelastic scattering of Lambda hyperons in the current and target fragmentation regions using the accumulated Jefferson Lab CLAS6 data-sets with deuterium, carbon, iron, and lead targets. Results on the multiplicity ratios and the transverse momentum broadening will be presented along with a highlight of the upcoming CLAS12 color propagation measurements. [Preview Abstract] |
Tuesday, April 20, 2021 3:57PM - 4:09PM Live |
Z15.00002: Hadronization Studies via $\omega(782)$ Electroproduction off D, C, Fe, and Pb Andres Borquez, Michael Wood, Hayk Hakobyan, William Brooks A complete picture of the strong interaction must include hadronization, the dynamical process of a free quark forming a color-neutral hardon. To study the hadronization of the vector meson $\omega(782)$, we perform semi-inclusive deep-inelastic scattering measurements on deuterium, carbon, iron, and lead using data collected with the CLAS detector at Jefferson Lab employing a 5.014 GeV electron beam. To examine nuclear dependence, we present $\omega$ multiplicities of the solid targets relative to those on deuterium as one-dimensional functions of the virtual-photon energy $\nu$, the photon virtuality $Q^2$, the fractional hadron energy $z$, and the square of the hadron transverse momentum $p_T^2$. This analysis corresponds to the first hadronization studies of the $\omega$ meson and hints at a promising future for upcoming CLAS12 and EIC experiments, where more detailed investigations could be achieved. [Preview Abstract] |
Tuesday, April 20, 2021 4:09PM - 4:21PM Live |
Z15.00003: Study of $\chi_{bJ}(nP)\to\omega\Upsilon(1S)$ at Belle Zachary Stottler We report on a search for the $\chi_{bJ}(nP)$ states of bottomonium at Belle. The P-wave states are reconstructed in decays to the $\Upsilon(1S)$ with the emission of an $\omega$ meson. The transitions of the $n=2$ triplet states provide a unique laboratory in which to study the non-relativistic limit of the QCD multipole expansion model (QCDME), as the kinematic threshold for production of an $\omega$ and $\Upsilon(1S)$ lies between the $J=0$ and $J=1$ states. A search for the $\chi_{bJ}(3P)$ states is also performed. [Preview Abstract] |
Tuesday, April 20, 2021 4:21PM - 4:33PM Live |
Z15.00004: $\Lambda_c$ baryon production at future EIC Yuanjing Ji In high energy collisions, heavy quarks (c, b) are predominately produced in the initial hard scattering process. The relative ratio of different heavy flavor hadrons species serves as a tool to study charm quark hadronization mechanism. Recently, data from $p$+$p$, $p$+A, and A+A collisions at RHIC and LHC showed that the $\Lambda_c^+/D^0$ ratio is considerably larger than the fragmentation baseline. The high luminosity e+p and e+A collisions in the future Electron-Ion Collider (EIC) at Brookhaven National Laboratory would allow us to systematically investigate the $\Lambda_c$ production over a broad kinematic region, which will shed detail insights on charm hadrochemistry and charm-quark hadronization. In this talk, I will present the reconstruction capability study for $\Lambda_c^+$ baryons at the future EIC experiment utilizing an all silicon tracker based on next generation MAPS technology. Physics projections on the measurement of $\Lambda_c^+/D^0$ ratio in e+p and e+A collisions in the future EIC will be presented. I will also discuss the physics potentials towards understanding the nucleon/nuclei structure and cold nuclear matter effects enabled by the $\Lambda_c^+$ measurements at EIC. [Preview Abstract] |
Tuesday, April 20, 2021 4:33PM - 4:45PM Live |
Z15.00005: Calculating Properties of Exotic Hadrons Using Supervised Machine Learning Emma Yeats, Dustin Keller The existence of exotic hadrons, consisting of more than three quarks, has long been speculated by the physics community. However, these particles have incredibly short lifetimes and are difficult to predict, as we currently don’t understand enough about them to have a dependable method of estimating their location on the mass spectra line. This research aims to use supervised learning methods, along with the data we currently possess on ordinary hadrons, to propose possible characteristics of exotic hadron configurations. After learning patterns from properties of mesons and baryons, the algorithm will report viable particle configurations and resonances as output data including, for instance, quark content, rest mass and lifetime estimates. In addition, as researchers in nuclear and particle physics have discovered several candidates of these exotic states at accelerator facilities in labs across the world (notably, the recent discoveries of tetraquarks at LHCb) these findings will be compared with the data reported on the exotic candidates that have been detected in laboratories thus far. [Preview Abstract] |
Tuesday, April 20, 2021 4:45PM - 4:57PM Live |
Z15.00006: Status of the PrimEx eta Radiative Decay Width Experiment in Hall D at Jefferson Lab Tyler Hague The PrimEx eta experiment (E12-10-011) at Jefferson Lab performed the first run of a new experiment in Hall D to measure the η radiative decay width with high precision using the GlueX experimental setup. In this experiment the $\eta\rightarrow\gamma\gamma$ decay width will be extracted from the photoproduction of η mesons at extreme forward angles using the so-called Primakoff effect. The two-photon decay of the \eta meson is predominantly due to Chiral anomaly in QCD. The projected 3.2% accuracy of the $\eta\rightarrow\gamma\gamma$ decay width measurement will significantly impact the η-sector of the Particle Data Group’s (PDG) compilation, sizably improving the average value on $\Gamma(\eta\rightarrow\gamma\gamma)$. That, in turn, will improve determination of the rest of the η partial decay widths. It will also significantly improve the $\eta-\eta\prime$ mixing angle. The first run of this experiment was in spring of 2019 to test the capability of the experimental setup. A rich and good statistics initial experimental data set was collected during this run. We are currently analyzing the data to check the experimental method and to prepare for the second full statistics run. The first preliminary physics distributions will be presented and discussed in this talk. [Preview Abstract] |
Tuesday, April 20, 2021 4:57PM - 5:09PM Not Participating |
Z15.00007: Preliminary measurement of the D$\rm{_{s}^{+}}$ lifetime using $\sim$ 70 fb$^{-1}$ of data collected by the Belle II experiment. Aman Sangal, Alan Schwartz We have measured the D$\rm{_{s}^{+}}$ lifetime by reconstructing the final state $\rm{\phi[\rightarrow K^{+}K^{-}] \pi^{+}}$. We have used $\rm{e^{+}e^{-}}$ collision data corresponding to an integrated luminosity of $~$70 fb$^{-1}$ collected by the Belle II experiment running at the SuperKEKB accelerator. This early measurement demonstrates the performance capabilities of the Belle II detector. [Preview Abstract] |
Tuesday, April 20, 2021 5:09PM - 5:21PM Live |
Z15.00008: Sensitivity study for a branching fraction measurement of $\Xi_c^+$ decays to $\Sigma^+ \pi^+ \pi^-$ at Belle II. Anil Panta, Jake Bennett The decay $\Xi_c^+ \to \Sigma^+ \pi^+ \pi^-$ is singly Cabibbo-suppressed, with a reported branching fraction of 0.48 $\pm$ 0.20 by the SELEX experiment with events of 21 $\pm$ 8 events. With the high statistics data samples that will be available at Belle II, this mode, along with other similar modes, will be useful for comprehensive searches for CP violation in charmed baryon decays. We report a sensitivity study for this mode, including the use of machine learning techniques like fast Boosted Decision Trees (BDT) for signal isolation. [Preview Abstract] |
Tuesday, April 20, 2021 5:21PM - 5:33PM Live |
Z15.00009: Production of $X(3872)$ at High Multiplicity Kevin Ingles, Eric Braaten, Li-Ping He, Jun Jiang The dependence of the production of the $X(3872)$ meson on the hadron multiplicity in $pp$ collisions has been used as evidence against $X$ being a charm-meson molecule. The argument is based in part on the incorrect assumption that the cross section for the breakup of $X$ by scattering with comovers can be approximated by a geometric cross section inversely proportional to the binding energy of $X$. The breakup cross section should instead be approximated by the probability-weighted sum of the cross sections for the scattering of comoving pions from the charm-meson constituents of $X$, which is insensitive to the binding energy. A simple modification of the comover interaction model gives excellent fits to the data from the LHCb collaboration on the multiplicity dependence of the production of $X$ and $\psi(2S)$ using parameters compatible with $X$ being a loosely bound charm-meson molecule. [Preview Abstract] |
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