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Nuclear Theory·nucl-th

Monday·December 10, 2018

8 papers—6 primary·2 cross-listed

All8Primary6Cross-lists2
  1. 01

    [Submitted on 6 Dec 2018]

    Initial transverse-momentum broadening of Breit-Wheeler process in relativistic heavy-ion collisions

    Wangmei Zha🇨🇳 · James Daniel Brandenburg🇨🇳 · Zebo Tang🇨🇳 · Zhangbu Xu🇨🇳

    We calculate the cross section and transverse-momentum () distribution of the Breit-Wheeler process in relativistic heavy-ion collisions and their dependence on collision impact parameter (). To accomplish this, the Equivalent Photon Approximation (EPA) was generalized in a more differential way compared to the approach traditionally used for inclusive collisions. In addition, a lowest-order QED calculation with straightline assumption was performed as a standard baseline for comparison. The cross section as a function of is consistent with previous calculations using the equivalent one-photon distribution function. Most importantly, the shape from this model is strongly dependent on impact parameter and can quantitatively explain the broadening observed recently by RHIC and LHC experiments. This broadening effect from the initial QED field strength should be considered in studying possible trapped magnetic field and multiple scattering in a Quark-Gluon Plasma (QGP). The impact-parameter sensitive observable also provides a controllable tool for studying extreme electromagnetic fields.

    Comments:
    3 figures, major update: 1. adding 2 more calculations with QED lowest-order Feynman diagrams, and gEPA1, and their equations; 2. adding more detailed explanations about the additional phase angle in gEPA2; 3. remove azimuthal angular calculation; 4. adding discussion about possible final-state effect
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1812.02820 [pdf]
    PLB(2020)·99 citations
  2. 02

    [Submitted on 7 Dec 2018]

    Description of the critical point symmetry in 124Te by IBM-2

    Dali Zhang🇨🇳 · Chengfu Mu🇨🇳

    Based on the neutron and proton degrees of freedom, the low-lying energy levels, the , and transition strengths of nucleus Te have been calculated by the neutron-proton interacting boson model. The calculated results are quite consistent with the experimental data. By comparing the key observables of states at the critical point of -- transition with experimental data and calculated results, we show that the Te is a possible nucleus at the critical point of the second order phase transition from vibration to unstable rotation and such a critical point contains somewhat triaxial rotation. The 0 state of Te can be interpreted as the lowest state of the first excited family of intrinsic levels in the critical point symmetry.

    Comments:
    19 pages, 1 figure, 3 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1812.02908 [pdf]
    CPC(2019)·1 citation
  3. 03

    [Submitted on 7 Dec 2018]

    Dependence of spin induced structural transitions on level density and Neutron emission spectra

    Mamta Aggarwal🇮🇳

    The impact of spin induced deformation and shape phase transitions on nuclear level density and consequently on neutron emission spectra of the decay of compound nuclear systems 112^Ru to 123^Cs (N = 68 isotones) is investigated in a microscopic framework of Statistical theory of superfluid nuclei. Our calculations are in good accord with experimental data for evaporation residue of 119^Sb^* and 185^Re^* and show a strong correlation between spin induced structural transitions and NLD. We find that the inverse level density parameter K increases with increasing spin for all the systems, but it decreases with a deformation or a shape change that results in the enhancement of level density and emission probability. A sharp shape phase transition from oblate to uncommon prolate non-collective in well deformed nuclei leads to band crossing and enhancement of level density which fades away while approaching sphericity at or near shell closure manifesting shell effects.

    Comments:
    6 pages, 8 figures. Accepted in Nuclear Physics A
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1812.02994 [pdf]
    NPA(2019)·4 citations
  4. 04

    [Submitted on 7 Dec 2018]

    Covariant chiral nucleon-nucleon contact Lagrangian up to order

    Yang Xiao🇨🇳 · Li-Sheng Geng🇨🇳 · Xiu-Lei Ren🇩🇪

    We adopt a covariant version of the naive dimensional analysis and construct the chiral two-nucleon contact Lagrangian constrained by Lorentz, parity, charge conjugation, hermitian conjugation, and chiral symmetries. We show that at , , , where denotes a generic small quantity, there are 4, 13, and 23 terms, respectively. We find that by performing expansions, the covariant Lagrangian reduces to the conventional non-relativistic one, which includes 2, 7, and 15 terms at each corresponding order.

    Comments:
    9 pages
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1812.03005 [pdf]
    PRC(2019)·41 citations
  5. 05

    [Submitted on 7 Dec 2018]

    Kaons and antikaons in strong magnetic fields

    Amruta Mishra🇮🇳 · Anuj Kumar Singh🇮🇳 · Neeraj Singh Rawat🇮🇳 · Pratik Aman🇮🇳

    The in-medium masses of the kaons and antikaons in strongly magnetized asymmetric nuclear matter are studied using a chiral SU(3) model. The medium modifications of the masses of these open strange pseudoscalar mesons arise due to their interactions with the nucleons and scalar mesons within the model. The proton, the charged nucleon, has effects from the Landau energy levels in the presence of the magnetic field. The anomalous magnetic moments (AMM) of the nucleons are taken into consideration in the present study and these are seen to be large at high magnetic fields and high densities. The isospin effects are appreciable at high densities. The density effects are observed to be the dominant medium effects, as compared to the effects from magnetic field and isospin asymmetry. ~

    Comments:
    22 pages, 4 figures, version to be published in Eur. Phys. Jour. A. arXiv admin note: text overlap with arXiv:1712.07997
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1812.03011 [pdf]
    EPJA(2019)·18 citations
  6. 06

    [Submitted on 7 Dec 2018]

    Entanglement Suppression and Emergent Symmetries of Strong Interactions

    Silas R. Beane🇺🇸 · David B. Kaplan🇺🇸 · Natalie Klco🇺🇸 · Martin J. Savage🇺🇸

    Entanglement suppression in the strong interaction -matrix is shown to be correlated with approximate spin-flavor symmetries that are observed in low-energy baryon interactions, the Wigner symmetry for two flavors and an symmetry for three flavors. We conjecture that dynamical entanglement suppression is a property of the strong interactions in the infrared, giving rise to these emergent symmetries and providing powerful constraints on the nature of nuclear and hypernuclear forces in dense matter.

    Comments:
    6 pages, 5 pages supplemental, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Quantum Physics (quant-ph)
    arXiv:
    1812.03138 [pdf]
    PRL(2019)·184 citations

Affiliations

first authorsco-authorsvia INSPIRE