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Nuclear Theory·nucl-th

Wednesday·March 23, 2022

10 papers—4 primary·6 cross-listed

All10Primary4Cross-lists6
  1. 05

    [Submitted on 31 Jan 2022] (cross-list from hep-ph)

    Nuclear transverse momentum imbalance in the color dipole approach at the LHC regime

    F. G. Ben🇧🇷 · A. V. Giannini🇧🇷 · M. V. T. Machado🇧🇷

    Transverse momentum broadening of a parton propagating through a large nucleus is evaluated in the color dipole approach using different models for the dipole cross section or unintegrated gluon distribution, which lead to different values of the coefficient . Numerical calculations are compared to data extracted from LHCb and ALICE experiments for nuclear broadening of . We find that different models which describe the small- data predict values of that agree reasonably well with experiment, specially for forward rapidity. The centrality dependence was also analysed and the models are consistent with the ALICE measurements.

    Comments:
    6 pages, 2 figure, 2 tables
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    2201.13432 [pdf]
    J.Phys.G(2022)·3 citations
  2. 06

    [Submitted on 21 Mar 2022] (cross-list from hep-ph)

    CP-violating axion interactions in effective field theory

    W. Dekens🇺🇸 · J. de Vries🇳🇱 · S. Shain🇳🇱

    Axions are introduced to explain the observed smallness of the term of QCD. Standard Model extensions typically contain new sources of CP violation, for instance to account for the baryon asymmetry of the universe. In the presence of additional CP-violating sources a Peccei-Quinn mechanism does not remove all CP violation, leading to CP-odd interactions among axions and Standard Model fields. In this work, we use effective field theory to parametrize generic sources of beyond-the-Standard-Model CP violation. We systematically compute the resulting CP-odd couplings of axions to leptons and hadrons by using chiral perturbation theory. We discuss in detail the phenomenology of the CP-odd axion couplings and compare limits from axion searches, such as fifth force and monopole-dipole searches and astrophysics, to direct limits on the CP-violating operators from electric dipole moment experiments. While limits from electric dipole moment searches are tight, the proposed ARIADNE experiment can potentially improve the existing constraints in a window of axion masses.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2203.11230 [pdf]
    JHEP(2022)·37 citations
  3. 07

    [Submitted on 21 Mar 2022] (cross-list from hep-ph)

    The medium-modified splitting function in the BDMPS-Z formalism

    Maximilian Attems🇨🇭 · Jasmine Brewer🇨🇭 · Gian Michele Innocenti🇨🇭 · Aleksas Mazeliauskas🇨🇭 · Sohyun Park🇨🇭 · Wilke van der Schee🇨🇭 · Urs Achim Wiedemann🇨🇭

    The formalism of Baier-Dokshitzer-Mueller-Peigné-Schiff and Zakharov determines the modifications of parton splittings in the QCD plasma that arise from medium-induced gluon radiation. Here, we study medium-modifications of the gluon splitting into a quark--anti-quark pair in this BDMPS-Z formalism. We derive a compact path-integral formulation that resums effects from an arbitrary number of interactions with the medium to leading order in the expansion. Analyses in the opacity and the saddle point approximations reveal two phenomena: a medium-induced momentum broadening of the relative quark--anti-quark pair momentum that increases the invariant mass of quark--anti-quark pairs, and a medium-enhanced production of such pairs. We note that both effects are numerically sizeable if the average momentum transfer from the medium is comparable to the quark mass. In ultra-relativistic heavy-ion collisions, this condition is satisfied for charm quarks. We therefore focus our numerical analysis on the medium modification of , although our derivation applies equally well to and to gluons splitting into light-flavoured quark--anti-quark pairs.

    Comments:
    58 pages, 12 figures; v2 corrected finite z-dependence, new derivation in section 7, conclusions unchanged. v3 small clarifications, published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2203.11241 [pdf]
    JHEP(2023)·36 citations
  4. 08

    [Submitted on 21 Mar 2022] (cross-list from cond-mat.quant-gas)

    The Gor'kov and Melik-Barkhudarov correction to an imbalanced Fermi gas in the presence of impurities

    Heron Caldas · S. Rufo · M. A. R. Griffith

    The effects of induced interactions are calculated in both clean and dirty situations, for balanced and imbalanced Fermi gases. We investigate the effects of nonmagnetic impurities on the induced interactions corrections to the transition temperature in the case of a balanced gas, and to the tricritical point in the case of an imbalanced Fermi gas at unitarity. We find that impurities act in detriment of the induced interactions, or particle-hole fluctuations, for the transition temperature and the tricritical point. For large impurity parameter, the particle-hole fluctuations are strongly suppressed. We have also found the Chandrasekhar-Clogston limit of an imbalanced Fermi gas at unitarity considering the effects of the induced interactions, both in the pure and impurity regimes.

    Comments:
    18 pages, 7 figures, to appear in Ann. Phys. (Berlin)
    Subjects:
    Quantum Gases (cond-mat.quant-gas); Strongly Correlated Electrons (cond-mat.str-el); Superconductivity (cond-mat.supr-con); Nuclear Theory (nucl-th)
    arXiv:
    2203.11388 [pdf]
    Annalen Phys.(2022)·1 citation
  5. 09

    [Submitted on 22 Mar 2022] (cross-list from astro-ph.CO)

    Simultaneous Inference of Neutron Star Equation of State and the Hubble Constant with a Population of Merging Neutron Stars

    Tathagata Ghosh🇮🇳 · Bhaskar Biswas🇮🇳 · Sukanta Bose🇮🇳

    We develop a method for implementing a proposal on utilizing knowledge of neutron star (NS) equation of state (EoS) for inferring the Hubble constant from a population of binary neutron star (BNS) mergers. This method is useful in exploiting BNSs as standard sirens when their redshifts are not available. Gravitational wave (GW) signals from compact object binaries provide a direct measurement of their luminosity distances, but not their redshifts. Unlike in the past, here we employ a realistic EoS parametrization in a Bayesian framework to simultaneously measure the Hubble constant and refine the constraints on the EoS parameters. The uncertainty in the redshift depends on the uncertainties in the EoS and the mass parameters estimated from GW data. Combining the inferred BNS redshifts with the corresponding luminosity distances, one constructs a redshift-distance relation and deduces the Hubble constant from it. Here, we show that in the Cosmic Explorer era, one can measure the Hubble constant to a precision of (with a credible interval) with a realistic distribution of a thousand BNSs, while allowing for uncertainties in their EoS parameters. Such a measurement can potentially resolve the current tension in the measurements of the Hubble constant from the early- and late-time universe. The methodology implemented in this work demonstrates a comprehensive prescription for inferring the NS EoS and the Hubble constant by simultaneously combining GW observations from merging NSs, while employing a simple population model for NS masses and keeping the merger rate of NSs constant in redshift. This method can be immediately extended to incorporate merger rate, population properties, and additional cosmological parameters.

    Comments:
    Published in PRD
    Subjects:
    Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
    arXiv:
    2203.11756 [pdf]
    PRD(2022)·56 citations
  6. 10

    [Submitted on 22 Mar 2022] (cross-list from hep-ph)

    Utilizing high- theory and data to constrain the initial stages of quark-gluon plasma

    Bojana Ilic🇷🇸 · Dusan Zigic🇷🇸 · Marko Djordjevic🇷🇸 · Magdalena Djordjevic🇷🇸

    The scarce knowledge of the initial stages of quark-gluon plasma before the thermalization is mostly inferred through the low- sector. We propose a complementary approach in this report - the use of high- probes' energy loss. We study the effects of four commonly assumed initial stages, whose temperature profiles differ only before the thermalization, on high- and predictions. The predictions are based on our Dynamical Radiative and Elastic ENergy-loss Approach (DREENA) framework. We report insensitivity of to the initial stages, making it unable to distinguish between different cases. displays sensitivity to the presumed initial stages, but current experimental precision does not allow resolution between these cases. We further revise the commonly accepted procedure of fitting the energy loss parameters, for each individual initial stage, to the measured . We show that the sensitivity of to various initial stages obtained through such procedure is mostly a consequence of fitting procedure, which may obscure the physical interpretations. Overall, the simultaneous study of high- observables, with unchanged energy loss parametrization and restrained temperature profiles, is crucial for future constraints on initial stages.

    Comments:
    12 pages, 5 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2203.11883 [pdf]
    IJMPE(2021)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE