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Nuclear Theory·nucl-th

Monday·March 23, 2020

9 papers—3 primary·6 cross-listed

All9Primary3Cross-lists6
  1. 04

    [Submitted on 19 Mar 2020] (cross-list from hep-ph)

    Dynamically assisted Schwinger mechanism and chirality production in parallel electromagnetic field

    Hidetoshi Taya🇨🇳

    We study particle and chirality production from the vacuum in the presence of a slow strong parallel electromagnetic field superimposed by a fast weak perturbative electromagnetic field. We derive an analytical formula for the particle and chirality production number based on the perturbation theory in the Furry picture. With the formula, we analytically discuss the interplay and dynamical assistance between the Schwinger mechanism and one-photon pair production and clarify effects of a parallel slow strong magnetic field. We also show that the dynamical assistance can significantly enhance chirality production, and that a sizable amount of chirality can be produced even for massive particles. Phenomenological applications including heavy-ion collisions and intense laser experiments are also discussed.

    Comments:
    17 pages, 5 figures; v2: references updated, typos corrected, to be published in PRR
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Plasma Physics (physics.plasm-ph); Quantum Physics (quant-ph)
    arXiv:
    2003.08948 [pdf]
    PRResearch(2020)·32 citations
  2. 05

    [Submitted on 19 Mar 2020] (cross-list from hep-ph)

    Baryon production probability via the nuclear configurational entropy

    G. Karapetyan🇧🇷

    We study the net-baryon production at forward rapidities within the Color Glass Condensate paradigm. At high energy regime, the leading baryon production mechanism is shown to change from recombination to independent fragmentation. The nuclear configurational entropy (NCE) constructed upon forward scattering amplitudes, allows to predict the two free parameters that govern the anomalous dimension of the target gluon distribution. The global minimum of the NCE indicates a point of stability in pp/pA/AA collisions at LHC energies, corroborating and matching HERA data for hadron spectra measured in pp and dAu collisions at RHIC energies, with accuracy between 1.2\% and 1.8\%, respectively for the two free parameters.

    Comments:
    5 pages, 2 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2003.08994 [pdf]
    Eur.Phys.J.Plus(2021)·18 citations
  3. 06

    [Submitted on 20 Mar 2020] (cross-list from physics.comp-ph)

    How machine learning conquers the unitary limit

    Bastian Kaspschak🇩🇪 · Ulf-G. Meißner🇩🇪

    Machine learning has become a premier tool in physics and other fields of science. It has been shown that the quantum mechanical scattering problem can not only be solved with such techniques, but it was argued that the underlying neural network develops the Born series for shallow potentials. However, classical machine learning algorithms fail in the unitary limit of an infinite scattering length and vanishing effective range parameters. The unitary limit plays an important role in our understanding of bound strongly interacting fermionic systems and can be realized in cold atom experiments. Here, we develop a formalism that explains the unitary limit in terms of what we define as unitary limit surfaces. This not only allows to investigate the unitary limit geometrically in potential space, but also provides a numerically simple approach towards unnaturally large scattering lengths with standard multilayer perceptrons. Its scope is therefore not limited to applications in nuclear and atomic physics, but includes all systems that exhibit an unnaturally large scale.

    Comments:
    4+4 pages, 5+4 figures
    Subjects:
    Computational Physics (physics.comp-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
    arXiv:
    2003.09137 [pdf]
    Commun.Theor.Phys.(2021)·7 citations
  4. 07

    [Submitted on 20 Mar 2020] (cross-list from hep-ph)

    Kaonic Hydrogen and Deuterium in Hamiltonian Effective Field Theory

    Zhan-Wei Liu🇨🇳 · Jia-Jun Wu🇨🇳 · Derek B. Leinweber🇦🇺 · Anthony W. Thomas🇦🇺

    The anti-kaon nucleon scattering lengths resulting from a Hamiltonian effective field theory analysis of experimental data and lattice QCD studies are presented. The same Hamiltonian is then used to compute the scattering length for the system, taking careful account of the effects of recoil on the energy at which the T-matrices are evaluated. These results are then used to estimate the shift and width of the levels of anti-kaonic hydrogen and deuterium. The result is in excellent agreement with the SIDDHARTA measurement. In the case the imaginary part of the scattering length and consequently the width of the state are considerably larger than found in earlier work. This is a consequence of the effect of recoil on the energy of the energy, which enhances the role of the resonance.

    Comments:
    7 pages, 3 figures, published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2003.09181 [pdf]
    PLB(2020)·23 citations
  5. 08

    [Submitted on 20 Mar 2020] (cross-list from math-ph)

    Bivariate -normal distribution for transition strengths distribution from many-particle random matrix ensembles generated by -body interactions

    V.K.B. Kota · Manan Vyas

    Recently it is established, via lower order moments, that the univariate q-normal distribution, which is the weight function for -Hermite polynomials, describes the ensemble averaged eigenvalue density from many-particle random matrix ensembles generated by -body interactions [Manan Vyas and V.K.B. Kota, J. Stat. Mech. {\bf 2019}, 103103 (2019)]. These ensembles are generically called embedded ensembles of -body interactions [EE()] and their GOE and GUE versions are called EGOE() and EGUE() respectively. Going beyond this work, the lower order bivariate reduced moments of the transition strength densities, generated by EGOE() [or EGUE()] for the Hamiltonian and an independent EGOE() for the transition operator that is -body, are used to establish that the ensemble averaged bivariate transition densities follow the bivariate -normal distribution. Presented are also formulas for the bivariate correlation coefficient and the values as a function of the particle number , number of single particle states that the particles are occupying and the body ranks and of and respectively. Finally, using the bivariate normal form a formula for the chaos measure number of principal components (NPC) in the transition strengths from a state with energy is presented.

    Comments:
    19 pages, 3 figures, 3 tables
    Subjects:
    Mathematical Physics (math-ph); math.MP (math.MP); nlin.CD (nlin.CD); Nuclear Theory (nucl-th)
    arXiv:
    2003.09191 [pdf]
    J.Stat.Mech.(2020)·7 citations
  6. 09

    [Submitted on 20 Mar 2020] (cross-list from hep-ph)

    Second Order Twist Contributions to the Balitsky-Kovchegov Equation at small-x: Deterministic and Stochastic Pictures

    Silas K Grossberndt🇺🇸

    We study the second order twist corrections to a toy model of a dipole-dipole interaction in the context of a both deterministic and stochastic effects. This work is done in the high limit in the Bjorken picture. We show that the correction to the second twist terms of the stochastic picture suggest additional importance of the second twist correction in the stochastic model as compared to the deterministic model.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2003.09303 [pdf]
    1 citation

Affiliations

first authorsco-authorsvia INSPIRE