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Nuclear Theory·nucl-th

Monday·November 1, 2021

8 papers—5 primary·3 cross-listed

All8Primary5Cross-lists3
  1. 06

    [Submitted on 29 Oct 2021] (cross-list from hep-ph)

    Suppression of thermal vorticity as an indicator of QCD critical point

    Sushant K. Singh🇮🇳 · Jan-e Alam🇮🇳

    We study the impact of the QCD critical point (CP) on the spin polarization of -hyperon generated by the thermal vorticity in viscous quark gluon plasma (QGP). The equations of the relativistic causal viscous hydrodynamics have been solved numerically in (3+1) dimensions to evaluate the thermal vorticity. The effects of the CP have been incorporated through the equation of state (EoS) and the scaling behavior of the transport coefficients. A significant reduction in the global polarization has been found as the CP is approached. A drastic change induced by the CP in the rapidity dependence of the spin polarization is observed which can be used as a signature of the CP.

    Comments:
    Latex file, 15 figures including supplementary material
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    2110.15604 [pdf]
    EPJC(2023)·19 citations
  2. 07

    [Submitted on 29 Oct 2021] (cross-list from nucl-ex)

    Measurement of Compton scattering at MAMI for the extraction of the electric and magnetic polarizabilities of the proton

    A2 Collaboration: E. Mornacchi (1) · P.P. Martel (1 and 2) · S. Abt (3) · P. Achenbach (1) · P. Adlarson (1) · F. Afzal (4) · Z. Ahmed (5) · J.R.M. Annand (6) · H.J. Arends (1) · M. Bashkanov (7) · R. Beck (4) · M. Biroth (1) and 53 other authors

    A precise measurement of the differential cross-sections and the linearly polarized photon beam asymmetry for Compton scattering on the proton below pion threshold has been performed with a tagged photon beam and almost detector at the Mainz Microtron. The incident photons were produced by the recently upgraded Glasgow-Mainz photon tagging facility and impinged on a cryogenic liquid hydrogen target, with the scattered photons detected in the Crystal Ball/TAPS set-up. Using the highest statistics Compton scattering data ever measured on the proton along with two effective field theories (both covariant baryon and heavy-baryon) and one fixed- dispersion relation model, constraining the fits with the Baldin sum rule, we have obtained the proton electric and magnetic polarizabilities with unprecedented precision: \begin{align*} &{}\alpha_{E1} = 10.99 \pm 0.16 \pm 0.47 \pm 0.17 \pm 0.34 &{}\beta_{M1} = 3.14 \pm 0.21 \pm 0.24 \pm 0.20 \pm 0.35 \end{align*} in units of \,fm where the errors are statistical, systematic, spin polarizability dependent and model dependent.

    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2110.15691 [pdf]
    PRL(2022)·22 citations
  3. 08

    [Submitted on 29 Oct 2021] (cross-list from nucl-ex)

    CME search at STAR

    Yu Hu (for the STAR Collaboration)🇨🇳

    The hot and dense medium produced in relativistic heavy-ion collisions has been conjectured to be accompanied by an axial charge asymmetry that may lead to a separation of electric charges in the direction of the extremely strong magnetic field, also known as the Chiral Magnetic Effect (CME). The measurement of azimuthal correlator () with respect to the spectator plane, gives us an opportunity to measure the possible CME fraction beyond the flow background. Preliminary results using this approach with combined Au+Au collisions at 200 GeV and U+U at 193 GeV show at . Meanwhile, the observability of CME has been conjectured to be dependent on due to changes in the lifetime of the magnetic field, the strengths of CME signal and non-CME background. At lower energies, the Event Plane Detector (EPD) installed in the year 2018 provides a unique capability for CME search. The background scenario test at Au+Au 27 GeV by using with respect to TPC and the new installed EPD shows a consistency with no-CME scenario in the current statistics. The method of the ongoing isobar blind analysis, and the latest sensitivity check with the event-by-event AVFD model on the different observables between Ru+Ru and Zr+Zr are also briefly discussed.

    Comments:
    4 pages, Online Strangeness in Quark Matter Conference 2021 (sQM 2021) proceedings
    Subjects:
    Nuclear Experiment (nucl-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2110.15937 [pdf]
    EPJ Web Conf.(2022)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE