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Nuclear Theory·nucl-th

Tuesday·October 8, 2019

16 papers—9 primary·7 cross-listed

All16Primary9Cross-lists7
  1. 10

    [Submitted on 21 May 2019] (cross-list from hep-ph)

    Flavor-changing hyperon decays with light invisible bosons

    Gang Li🇹🇼 · Jhih-Ying Su🇹🇼 · Jusak Tandean🇹🇼

    We consider the strangeness-changing decays of hyperons into another baryon and missing energy which is carried away by a pair of invisible spinless bosons. Pursuing a model-independent approach and taking into account constraints from the kaon sector, we find that these hyperon modes can have large rates, especially if the bosons have parity-odd effective couplings to light quarks. In that case the rates could attain values which are well within the expected reach of the currently running BESIII experiment. Since the branching fractions of hyperon decays with missing energy are tiny in the standard model, observing them at ongoing or upcoming facilities would likely be indicative of new physics. In addition, we show that the kaon restrictions may be weakened or absent if the bosons have nonnegligible mass. Specifically, if the bosons interact with the quarks solely via an axial-vector current, in the mass region from about 115 to 175 MeV the constraints from rare kaon decays no longer apply and a couple of the hyperon modes become the only direct probes of such interactions. We also make comparisons with the previously explored new-physics scenario where the invisible particles are spin-1/2 fermions.

    Comments:
    15 pages, 3 figures, slightly modified, matches journal version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1905.08759 [pdf]
    PRD(2019)·12 citations
  2. 11

    [Submitted on 3 Oct 2019] (cross-list from hep-ph)

    Chiral instabilities & the onset of chiral turbulence in QED plasmas

    Mark Mace🇫🇮 · Niklas Mueller🇺🇸 · Sören Schlichting🇩🇪 · Sayantan Sharma🇮🇳

    We present a first principles study of chiral plasma instabilities and the onset of chiral turbulence in QED plasmas far from equilibrium. By performing classical-statistical lattice simulations of the microscopic theory, we show that the generation of strong helical magnetic fields from a helicity imbalance in the fermion sector proceeds via three distinct phases. During the initial linear instability regime the helicity imbalance of the fermion sector causes an exponential growth(damping) of magnetic field modes with right(left) handed polarization, for which we extract the characteristic growth (damping) rates. Secondary growth of unstable modes accelerates the helicity transfer from fermions to gauge fields and ultimately leads to the emergence of a self-similar scaling regime characteristic of decaying turbulence, where magnetic helicity is efficiently transferred to macroscopic length scales. Within this turbulent regime the evolution of magnetic helicity spectrum can be described by an infrared power-spectrum with spectral exponent and dynamical scaling exponents , which we determine from our simulations.

    Comments:
    published in Physical Review Letters, 13 pages, 9 figures (incl. supplemental material). Details of lattice implementation and numerical analysis strategy significantly expanded
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1910.01654 [pdf]
    PRL(2020)·45 citations
  3. 12

    [Submitted on 4 Oct 2019] (cross-list from hep-ph)

    Transition Distribution Amplitudes : from JLab to EIC

    L. Szymanowski🇵🇱 · B. Pire🇫🇷 · K. Semenov-Tian-Shansky🇷🇺

    Baryon-to-meson Transition Distribution Amplitudes extend both the concepts of generalized parton distributions and baryon distribution amplitudes encoding valuable complementary information on the 3-dimensional hadronic structure. The recent analysis of backward meson electroproduction at JLab supports the hope to perform femto-photography of hadrons from a brand new perspective.and in particular opens a new domain for EIC experiments.

    Comments:
    4 pages, 3 figures, proccedings of the INT program 18-3 : Probing Nucleons and Nuclei in High Energy Collisions, to be published by World Scientific
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1910.01979 [pdf]
    2 citations
  4. 13

    [Submitted on 4 Oct 2019] (cross-list from hep-ph)

    Improved opacity expansion for medium-induced parton splitting

    Yacine Mehtar-Tani🇺🇸 · Konrad Tywoniuk🇳🇴

    We present a new expansion scheme to compute the rate for parton splittings in dense and finite QCD media. In contrast to the standard opacity expansion, our expansion is performed around the harmonic oscillator whose characteristic frequency depends on the typical transverse momentum scale generated in the splitting. The first two orders account for the high frequency regime that is dominated by single hard scatterings together with the regime of multiple soft scatterings at low frequency. This work generalizes the findings of Ref. \cite{Mehtar-Tani:2019tvy} beyond the leading logarithmic approximation allowing to account also for the Bethe-Heitler regime and compare to the full numerical results from Ref. \cite{CaronHuot:2010bp}. We investigate the sensitivity of our results to varying the separation scale that defines the leading order. Finally, the application to Monte Carlo event generators is discussed.

    Comments:
    16 pages, 4 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1910.02032 [pdf]
    JHEP(2020)·70 citations
  5. 14

    [Submitted on 5 Oct 2019] (cross-list from cond-mat.stat-mech)

    The Concealed Voter Model is in the Voter Model universality class

    Rosalba Garcia-Millan

    The Concealed Voter Model (CVM) is an extension of the original Voter Model, where two different opinions compete until consensus is reached. In the CVM, agents express an opinion not only publicly, they also hold a private opinion, which they may disclose or change. In this paper I derive the critical exponents of both models via renormalised field theory and show that both belong to the compact directed percolation universality class.

    Comments:
    9 pages, 2 figures
    Subjects:
    Statistical Mechanics (cond-mat.stat-mech); Nuclear Theory (nucl-th)
    arXiv:
    1910.02315 [pdf]
    J.Stat.Mech.(2020)·2 citations
  6. 15

    [Submitted on 6 Oct 2019] (cross-list from hep-th)

    Bridging the Chiral symmetry and Confinement with Singularity

    Yoon-Seok Choun🇰🇷 · Sang-Jin Sin🇰🇷

    We consider a holographic quark model where the confinement is a consequence of the quark condensate. Surprisingly, the equation of motion of our holographic model can be mapped to the old spin-less bag model. Both models correctly reproduce the linear Regge trajectory of hadrons for zero quark mass. For the case of non-zero quark mass, the model lead us to Heun's equation. The mass term is precisely the origin of the higher singularity, which changes the system behavior drastically. Our result can shed some light on why the chiral transition is so close to the confinement transition. In the massive case, the Schroedinger equation is exactly solvable, but only if a surprising new quantization condition, additional to the energy quantization, is applied.

    Comments:
    Accepted by Physics Letters B
    Subjects:
    High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1910.02383 [pdf]
    PLB(2020)·4 citations
  7. 16

    [Submitted on 7 Oct 2019] (cross-list from hep-ph)

    On the shape of the asymmetry

    A. Accardi · C.E. Keppel · S. Li · W. Melnitchouk · J.F. Owens

    Using data from a recent reanalysis of neutron structure functions extracted from inclusive proton and deuteron deep-inelastic scattering (DIS), we re-examine the constraints on the shape of the asymmetry in the proton at large parton momentum fractions . A global analysis of the proton-neutron structure function difference from BCDMS, NMC, SLAC and Jefferson Lab DIS measurements, and of Fermilab Drell-Yan lepton-pair production cross sections, suggests that existing data can be well described with for all values of currently accessible. We compare the shape of the fitted distributions with expectations from nonperturbative models based on chiral symmetry breaking, which can be tested by upcoming Drell-Yan data from the SeaQuest experiment at larger values of .

    Comments:
    17 pages, 6 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1910.02931 [pdf]
    PLB(2020)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE