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 S20: Aspects of QCDLive
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Sponsoring Units: DPF Chair: Dmitri Denisov, BNL |
Monday, April 19, 2021 1:30PM - 1:42PM Live |
S20.00001: Search for $W_{bj}$ states in $\Upsilon(5S)$ decays Vladimir Savinov, Nicholas Corrado The recent discovery of the states $Z_b$ and $Z_b^\prime$ implies the possible existence of a new family of hadronic resonances including molecular states dubbed $W_{bJ}$. We describe a search for $W_{bJ}$ in $\Upsilon(5S)$ decays using 121.4 ${\rm fb^{-1}}$ of data collected with the Belle detector at the KEKB asymmetric-energy electron-positron collider. [Preview Abstract] |
Monday, April 19, 2021 1:42PM - 1:54PM Live |
S20.00002: Probing for Intrinsic Charm at LHCb Daniel Craik There is considerable interest in the possibility that the proton wave function may contain some intrinsic charm (IC). In particular, the presence of IC in the proton may affect a range of processes: from cross sections relevant to Higgs production and dark-matter detection at the LHC to the rate and kinematics of charm hadrons produced by cosmic rays interacting with the Earth's upper atmosphere (an important background to astrophysical neutrinos). The IC of the proton may be probed at the LHC by studying the production of $Z$ bosons in association with a charm jet in the forward region, which may proceed via $gc\rightarrow Zc$ interactions. We present results from a study of this process based on data collected during Run 2 of the LHCb experiment. [Preview Abstract] |
Monday, April 19, 2021 1:54PM - 2:06PM Live |
S20.00003: Computing the mass of flavor singlet uuddss with QCD sum rules Zihui Wang, Glennys Farrar It is recently argued that a deeply-bound six-quark uuddss state could have evaded all experimental searches and is a dark matter candidate. In the past, the QCD sum rules have been applied to compute the mass of weakly-bound H-dibaryons. However, the traditional perception of the H-dibaryon as di-Lambda or triple-diquark does not fully account for the color-flavor-spin structure of the total singlet uuddss. The complete wavefunction of the singlet uuddss is highly entangled in color-spin-flavor, and we discuss the consequence to predicting its mass using QCD sum rules. [Preview Abstract] |
Monday, April 19, 2021 2:06PM - 2:18PM Live |
S20.00004: A Review of Functional Renormalization Group approach to the current quark mass dependence of criticality within the Two-Flavor Quark-Meson Model Muniba Fatima, Amber Jamal, Imran Siddiqui Increasing the number of hadrons into a finite size nuclei, so as to remove the physical vacuum, causes a singularity to occur, the phenomenon is used to be explain with QCD phase diagram which is a function of temperature, $T$, and chemical baryon potential, \begin{figure}[htbp] \centerline{\includegraphics[width=0.18in,height=0.20in]{081220201.eps}} \label{fig1} \end{figure} . In this submission, the authors will give a review on the present state of understanding of properties of phase transition region and behavior exhibited during phase transition process from hadronic matter to quark-gluon plasma by the functional renormalization group (FRG) approach to reveal useful information about the criticality in QCD. Our research work is mainly to use FRG within the two-flavor quark meson model to reveal information about criticality in QCD.. [Preview Abstract] |
Monday, April 19, 2021 2:18PM - 2:30PM Live |
S20.00005: Characterizing the chemical freeze-out in heavy-ion collisions by thermal-model analyses Jamie Stafford, Paolo Alba, Valentina Mantovani-Sarti, Jacquelyn Noronha-Hostler, Paolo Parotto, Israel Portillo, Claudia Ratti We present results on the influence of hadronic resonances on the chemical freeze-out in heavy-ion collisions [1, 2]. By varying the number of particle states in our model calculations, we determine the effect of the hadronic spectrum on thermal fit parameters. Our input hadronic lists under study range from ones with relatively few particles to those that consider experimentally observed and theoretically predicted states. We calculate thermal fits of particle yields and net-particle fluctuations within the Hadron Resonance Gas model for each set of particle states. From these analyses, we extract the relevant freeze-out conditions for each set and confirm that the results are consistent between the two methods. Furthermore, we find that the presence of additional resonances tends to decrease the freeze-out temperature, while only mildly affecting the baryonic chemical potential. We also note that the inclusion of heavier resonances is not sufficient to eliminate the gap between the freeze-out conditions for light and strange particles. [1] P. Alba et al. Phys.Rev.C 101 054905 (2020) [2] R. Bellwied et al. Phys.Rev.C 99 034912 (2019) [Preview Abstract] |
Monday, April 19, 2021 2:30PM - 2:42PM Live |
S20.00006: Search for collectivity in high multiplicity DIS and photo-production e+p collisions with H1 at HERA Chuan Sun, Zhoudunming Tu, Stefan Schmitt, Austin Baty, Wei Li, Zhenyu Chen Observations of two- and multi-particle correlations in high multiplicity p-A, p-p and ultra-peripheral Pb+Pb collisions at RHIC and LHC reveal the collective nature of particle production in small collision systems. These results motivate a study in even smaller systems such as e+p collisions in order to understand the origin of the observed collectivity. With data collected by the H1 experiment at HERA, two- and multi-particle correlations in collisions of electron at 27.6 GeV and proton at 920 GeV are measured as a function of multiplicity for deep inelastic scattering events, as well as for photo-production events for the first time. Those results are compared to available Monte Carlo models and are complementary to the studies of collectivity in other small systems. [Preview Abstract] |
Monday, April 19, 2021 2:42PM - 2:54PM Live |
S20.00007: QCD Equation of State and Phase Diagram from Holographic Black Holes Joaquin Grefa, Claudia Ratti, Israel Portillo, Romulo Rougemont, Jacquelyn Noronha-Hostler, Jorge Noronha By using the holographic model from [1], which reproduces the lattice QCD equation of state for small baryon chemical potential and predicts a critical end point, we locate the first order phase transition line, and obtain the QCD equation of state for a large region in the QCD phase diagram. We calculate the critical exponents for the holographic critical point and compare them with other critical points from the literature. [1] Critelli, R., Noronha, R., Noronha-Hostler, J., Portillo, I., Ratti, C., Rougemont, R. Phys.Rev.D 96 (2017) 9, 096026 [Preview Abstract] |
Monday, April 19, 2021 2:54PM - 3:06PM Live |
S20.00008: Compositeness, Bargmann-Wigner solutions within a U(1)-interaction quantum-field-theory expansion, and charge Jaime Besprosvany New solutions of the Bargmann-Wigner equations are obtained: free fermion-antifermion pairs, each satisfying Dirac's equation, with parallel momenta and momenta on a plane, produce vectors satisfying Proca's equations. These equations are consistent with Dirac's and Maxwell's equations, as zero-order conditions within a Lagrangian expansion for the U(1)-symmetry quantum field theory. Such vector solutions' demand that they satisfy Maxwell's equations and quantization fix the charge. The current equates the vector field, reproducing the superconductivity London equations, thus, binding and screening conditions. The derived vertex connects to QCD superconductivity a constrains four-fermion interaction composite models. Reference: arXiv:2101.01347 [Preview Abstract] |
Monday, April 19, 2021 3:06PM - 3:18PM Live |
S20.00009: Hadonization on Heavy-Ion Collisions in quark-gluon plasma Suresh Ahuja The QGP behaves like a near-perfect fluid with small specific shear viscosity, as revealed by the collective flow patterns in final-state hadron spectra being consistent with relativistic hydrodynamic simulations The recent experimental measurements on pp collisions at $\surd $s$=$13TeV and 5.02TeV have shown a very large abundance of heavy baryon production corresponding to a ratio of $\Lambda $c/D0 $\sim $ 0.6, about one order of magnitude larger than what measured in e$+$e$-$, ep collisions and even in pp collisions at LHC, but at forward rapidity. The enhanced ratio of baryon to meson and number of constituent quark scaling for elliptic flows of hadrons at the intermediate transverse momentum (pT ) are typical experimental signals for quark combination mechanism at hadronization. Heavy-quark transport from various model with their default parameters vary, however, by up to a factor of 5 at high momenta. Charmed hadron production in relativistic heavy-ion collisions can result in coalescence that includes hadronic states as well as the strict energy-momentum conservation, which ensures the boost invariance of the coalescence probability and the thermal limit of the produced hadron spectrum. By combining hadronization scheme with an advanced Langevin-hydrodynamics result in incorporating both elastic and inelastic energy loss of heavy quarks inside the dynamical quark-gluon plasma. Ration of $\Lambda $c/D0 and D-meson elliptic flow\textit{ are analyzed }at RHIC and the LHC. . Larger $\Lambda $c/D0 observed in Au$+$Au collisions at RHIC than in Pb$+$Pb collisions at the LHC is due to the interplay between the effects of the QGP radial flow and the charm quark transverse momentum spectrum at hadronization. It is also analyzed that charmed hadrons have larger sizes in medium than [Preview Abstract] |
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