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Nuclear Theory·nucl-th

Friday·November 13, 2015

16 papers—9 primary·7 cross-listed

All16Primary9Cross-lists7
  1. 10

    [Submitted on 10 Nov 2015] (cross-list from hep-ph)

    Will protons become gray at 13 TeV and 100 TeV?

    I.M. Dremin🇷🇺

    It is shown that the regime of pp-interactions at 7 TeV is a critical one. The LHC data about elastic pp-scattering at 7 and 8 TeV are used to get some information about both elastic and inelastic profiles of pp-collisions. They are discussed in the context of two phenomenological models which pretend to describe the high energy pp-data with high accuracy. Some predictions following from these models for LHC energy 13 TeV and for energy 95 TeV of the newly proposed collider are discussed. It is claimed that the center of the inelastic interaction region will become less dark with increase of energy albeit very slowly.

    Comments:
    7 pages
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1511.03212 [pdf]
    Bull.Lebedev Phys.Inst.(2017)·9 citations
  2. 11

    [Submitted on 12 Nov 2015] (cross-list from hep-ph)

    Study of entropy production in Yang-Mills theory with use of Husimi function

    Hidekazu Tsukiji🇯🇵 · Hideaki Iida🇯🇵 · Teiji Kunihiro🇯🇵 · Akira Ohnishi🇯🇵 · Toru T. Takahashi🇯🇵

    Understanding the thermalization process in a pure quantum system is a challenge in theoretical physics. In this work, we explore possible thermalization mechanism in Yang-Mills(YM) theory by using a positive semi-definite quantum distribution function called a Husimi function which is given by a coarse graining of the Wigner function within the minimum uncertainty. Then entropy is defined in terms of the Husimi function, which is called the Husimi-Wehrl(HW) entropy. We propose two numerical methods to calculate the HW entropy. We find that it is feasible to apply the semi-classical approximation with the use of classical YM equation. It should be noted that the semi-classical approximation is valid in the systems of physical interest including the early stage of heavy-ion collisions. Using a product ansatz for the Husimi function, which is confirmed to reproduce the HW entropy within 20% error (overestimate) for a few-body quantum system, we succeed in a numerical evaluation of HW entropy of YM fields and show that it surely has a finite value and increases in time.

    Comments:
    7 pages, 5 figures, Proceeding of the 33rd International Symposium on Lattice Field Theory (Lattice 2015), 14-18 July 2015, Kobe International Conference Center, Kobe, Japan
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    1511.03804 [pdf]
    PoS(2016)·0 citations
  3. 12

    [Submitted on 12 Nov 2015] (cross-list from nucl-ex)

    Heavy-ion double charge exchange reactions: a tool towards 0v\b{eta}\b{eta} nuclear matrix elements

    F. Cappuzzello🇮🇹 · M. Cavallaro🇮🇹 · C. Agodi🇮🇹 · M. Bond`ı🇮🇹 · D. Carbone🇮🇹 · A. Cunsolo🇮🇹 · A. Foti🇮🇹

    The knowledge of the nuclear matrix elements for the neutrinoless double beta decay is fundamental for neutrino physics. In this paper, an innovative technique to extract information on the nuclear matrix elements by measuring the cross section of a double charge exchange nuclear reaction is proposed. The basic point is that the initial and final state wave functions in the two processes are the same and the transition operators are similar. The double charge exchange cross sections can be factorized in a nuclear structure term containing the matrix elements and a nuclear reaction factor. First pioneering experimental results for the 40Ca(18O,18Ne)40Ar reaction at 270 MeV incident energy show that such cross section factorization reasonably holds for the crucial 0+ --> 0+ transition to 40Args, at least at very forward angles.

    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1511.03858 [pdf]
    EPJA(2015)·152 citations
  4. 13

    [Submitted on 12 Nov 2015] (cross-list from hep-ph)

    QCD running in neutrinoless double beta decay: Short-range mechanisms

    M. González🇨🇱 · M. Hirsch🇪🇸 · S.G. Kovalenko🇨🇱

    The decay rate of neutrinoless double beta () decay contains terms from heavy particle exchange, which lead to dimension-9 (d=9) six fermion operators at low energies. Limits on the coefficients of these operators have been derived previously neglecting the running of the operators between the high-scale, where they are generated, and the energy scale of double beta decay, where they are measured. Here we calculate the leading order QCD corrections to all possible d=9 operators contributing to the amplitude and use RGE running to calculate 1-loop improved limits. Numerically, QCD running changes limits by factors of the order of or larger than typical uncertainties in nuclear matrix element calculations. For some specific cases, operator mixing in the running changes limits even by up to two orders of magnitude. Our results can be straightforwardly combined with new experimental limits or improved nuclear matrix element calculations to re-derive updated limits on all short-range contributions to decay.

    Comments:
    Updated after erratum 16 pages, 3 figures, 2 tables
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1511.03945 [pdf]
    PRD(2016)·41 citations
  5. 14

    [Submitted on 12 Nov 2015] (cross-list from hep-lat)

    On the nature of an emergent symmetry in QCD

    Thomas D. Cohen🇺🇸

    Remarkable symmetry properties appear to arise in lattice calculations of correlation functions in which the lowest-lying eigenmodes of the Dirac operator in quark propagators are removed by hand. The Banks-Casher relation ties the chiral condensate to the density of low lying modes; thus, it is plausible that removal of such modes could lead to a regime where spontaneous chiral symmetry breaking does not occur. Surprising, a pattern of identical correlation functions was observed that is larger than can be explained by a restoration of chiral symmetry. This suggests that a larger symmetry---one that is not present in the QCD lagrangian---emerges when these modes are removed. Previously it was argued that this emergent symmetry was SU(4). However, when the low-lying modes are removed, the correlation functions of sources in the SU(4) 15-plet of spin-1 mesons appear to coincide with the correlation function of the SU(4) singlet. A natural explanation for this is an emergent symmetry larger than SU(4). In this work, it is shown that there exists no continuous symmetry whose generators in the field theory are spatial integrals of local operators that can account for the full pattern of identical correlation functions unless the apparent coincidence of the singlet channel with the 15-plet is accidental.

    Comments:
    References added; A few clarifying comments added
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1511.03956 [pdf]
    PRD(2016)·13 citations
  6. 15

    [Submitted on 3 Nov 2015] (cross-list from math.CA)

    q-Gamow States as continuous linear functionals on analytical test functions

    A. Plastino · M. C. Rocca

    We define here q-Gamow states corresponding to Tsallis' q-statistics. We compute for them their norm, mean energy value an the q-analogue of the Breit-Wigner distribution (a q-Breit-Wigner).

    Comments:
    11 pages. No figures
    Subjects:
    math.CA (math.CA); Statistical Mechanics (cond-mat.stat-mech); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    1511.04010 [pdf]
    NPA(2016)·6 citations
  7. 16

    [Submitted on 12 Nov 2015] (cross-list from hep-ph)

    Chiral Magnetic and Vortical Effects in High-Energy Nuclear Collisions --- A Status Report

    D. E. Kharzeev🇺🇸 · J. Liao🇺🇸 · S. A. Voloshin🇺🇸 · G. Wang🇺🇸

    The interplay of quantum anomalies with magnetic field and vorticity results in a variety of novel non-dissipative transport phenomena in systems with chiral fermions, including the quark-gluon plasma. Among them is the Chiral Magnetic Effect (CME) -- the generation of electric current along an external magnetic field induced by chirality imbalance. Because the chirality imbalance is related to the global topology of gauge fields, the CME current is topologically protected and hence non-dissipative even in the presence of strong interactions. As a result, the CME and related quantum phenomena affect the hydrodynamical and transport behavior of strongly coupled quark-gluon plasma, and can be studied in relativistic heavy ion collisions where strong magnetic fields are created by the colliding ions. Evidence for the CME and related phenomena has been reported by the STAR Collaboration at Relativistic Heavy Ion Collider at BNL, and by the ALICE Collaboration at the Large Hadron Collider at CERN. The goal of the present review is to provide an elementary introduction into the physics of anomalous chiral effects, to describe the current status of experimental studies in heavy ion physics, and to outline the future work, both in experiment and theory, needed to eliminate the existing uncertainties in the interpretation of the data.

    Comments:
    Invited review for Progress in Particle and Nuclear Physics; 38 pages, 25 figures; v2 matching published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1511.04050 [pdf]
    PPNP(2016)·837 citations

Affiliations

first authorsco-authorsvia INSPIRE