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Nuclear Theory·nucl-th

Wednesday·March 24, 2021

4 papers—4 primary·0 cross-listed

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  1. 01

    [Submitted on 23 Mar 2021]

    Cross sections of solar neutrino capture by 127I nuclei and Gamow Teller resonances

    Yu.S. Lutostansky🇷🇺 · A.N. Fazliakhmetov🇷🇺 · G.A. Koroteev🇷🇺 · N.V. Klochkova🇷🇺 · A.P. Osipenko🇷🇺 · V.N. Tikhonov🇷🇺

    Solar neutrino capture cross-section by 127I nucleus has been studied with taking into account the influence of the resonance structure of the nuclear strength function S(E). Three types of isobaric resonances: giant Gamow-Teller, analog resonance and low-lying Gamow-Teller pigmy resonances has been investigated on the framework of self-consistent theory of finite Fermi systems. The calculations have been performed considering the resonance structure of the charge-exchange strength function S(E). We analyze the effect of each resonance on the energy dependence of the cross-section. It has been shown that all high-lying resonances should be considered. Neutron emission process for high energy nuclear excitation leads to formation 126Xe isotope. We evaluate contribution from various sources of solar neutrinos to the 126Xe/127Xe isotopes ratio formed by energetic neutrinos. 126Xe/127Xe isotope ratio could be an indicator of high-energy boron neutrinos in the solar spectrum. We also discuss the uncertainties in the often used Fermi-functions calculations.

    Comments:
    18 pages, 9 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2103.12325 [pdf]
    3 citations
  2. 02

    [Submitted on 23 Mar 2021]

    Estimation of initial state structures in high energy heavy-ion collisions using Principal Component Analysis (PCA)

    Shreyasi Acharya🇮🇳 · Subhasis Chattopadhyay🇮🇳

    In high-energy heavy-ion collisions, structures in the initial collision zone are a matter of intense investigation, both from theory and experimental points of view. A large number of models have been developed to represent the initial state of the collision including Glauber model, Colour Glass Condensate (CGC) among others. Another important aspect of the study is to investigate proper observables that will be sensitive to the initial collision zone. In this work, we have discussed a formalism to implement the spatial clusters at the partonic level in the string melting version of the AMPT model for PbPb collisions at = 200 GeV. These clusters are then propagated through the AMPT hadronization scheme. The Principal Component Analysis (PCA) has been used on the , and distributions of the produced charged particles and the eigenvalues have been compared before and after the implementation of the clustering. It is found that for all these three different distributions, all the prominent PCA modes have shown sensitivity to the clustering. A centrality dependent study has also been performed on those eigenvalues.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2103.12380 [pdf]
    PRC(2021)·8 citations
  3. 03

    [Submitted on 23 Mar 2021]

    Thermoelectric response of a weakly magnetized thermal QCD medium

    Debarshi Dey🇮🇳 · Binoy Krishna Patra🇮🇳

    We estimate the thermoelectric response, namely, the Seebeck and Nernst coefficients of a hot and deconfined plasma of quarks and gluons, created post ultrarelativistic heavy ion collisions in the presence of a weak, homogeneous background magnetic field. We employ the kinetic theory framework, wherein we use the relativistic Boltzmann transport equation in the relaxation time approximation. In-medium interactions are taken into account via the quasiparticle masses of the partons extracted from one loop perturbative thermal QCD. We calculate the individual and total Seebeck coefficients in 2 different approaches (1-D and 2-D formulations). In the 1-D analysis, we find that a larger current quark mass has an amplifying effect on the individual Seebeck coefficient in the presence of a weak magnetic field. The temperature sensitivities of the individual Seebeck coefficients increase with increase in the current mass of the quark species in the case of a weak magnetic field whereas the same records a decreasing trend in the presence of a strong magnetic field. The variation of individual and total Seebeck coefficients with temperature, chemical potential and background magnetic field are found to follow similar trends in both the approaches, viz. decrease in magnitude with increasing temperature and increase in magnitude with increase in chemical potential and magnetic field. We also calculate the individual and total Nernst coefficients (in 2-D formulation) which are found to decrease with both temperature and chemical potential and increase with the magnetic field. Further, we find that the sign of the Nernst coefficient is independent of the electric charge of the charge carrier of the medium.

    Comments:
    36 pages, 22 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2103.12471 [pdf]
    PRD(2021)·12 citations
  4. 04

    [Submitted on 23 Mar 2021]

    Unnuclear physics

    Hans-Werner Hammer🇩🇪 · Dam Thanh Son🇺🇸

    We investigate a nonrelativistic version of Georgi's "unparticle physics." We define the unnucleus as a field in a nonrelativistic conformal field theory. Such a field is characterized by a mass and a conformal dimension. We then consider the formal problem of scatterings to a final state consisting of a particle and an unnucleus and show that the differential cross section, as a function of the recoil energy received by the particle, has a power-law singularity near the maximal recoil energy, where the power is determined by the conformal dimension of the unnucleus. We argue that unlike the relativistic unparticle, which remains a hypothetical object, the unnucleus is realized, to a good approximation, in nuclear reactions involving emission of a few neutrons, when the energy of the final-state neutrons in their center-of-mass frame lies in the range between about 0.1 MeV and 5 MeV. Combining this observation with the known universal properties of fermions at unitarity in a harmonic trap, we predict a power-law behavior of an inclusive cross section in this kinematic regime. We compare our predictions with previous effective field theory and model calculations of the He, H, and H reactions and find excellent agreement.

    Comments:
    13 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
    arXiv:
    2103.12610 [pdf]
    Proc.Nat.Acad.Sci.(2021)·35 citations

Affiliations

first authorsco-authorsvia INSPIRE