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Nuclear Theory·nucl-th

Tuesday·February 3, 2015

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 06

    [Submitted on 2 Feb 2015] (cross-list from hep-ph)

    Top-down Holographic Glueball Decay Rates

    F. Brünner🇦🇹 · D. Parganlija🇦🇹 · A. Rebhan🇦🇹

    We present new results on the decay patterns of scalar and tensor glueballs in the top-down holographic Witten-Sakai-Sugimoto model. This model, which has only one free dimensionless parameter, gives semi-quantitative predictions for the vector meson spectrum, their decay widths, and also a gluon condensate in agreement with SVZ sum rules. The holographic predictions for scalar glueball decay rates are compared with experimental data for the widely discussed gluon candidates f0(1500) and f0(1710).

    Comments:
    9 pages, 2 figures, 2 tables; to appear in the Proceedings of the XIth Conference Quark Confinement and the Hadron Spectrum, St. Petersburg, September 8-12, 2014
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1502.00456 [pdf]
    AIP Conf.Proc.(2016)·3 citations
  2. 07

    [Submitted on 2 Feb 2015] (cross-list from nucl-th)

    Elastic scattering of hadrons without optical theorem

    Jiri Prochazka🇨🇿 · Vojtech Kundrat🇨🇿 · Milos V. Lokajicek🇨🇿

    All contemporary phenomenological models of elastic hadronic scattering have been based on the assumption of validity of optical theorem that was overtaken from optics. It has been stated that it may be proven in particle physics. However, it will be shown that its derivation in the framework of unitary S-matrix theory (which is supposed to be the most general approach in this case) has been based on several requirements that do not correspond to the actual collision characteristics of two particles. It will be shown that especially in the case of short-ranged interaction (for which the theorem is used most frequently) it cannot be applied to. The analysis of corresponding collision experiments is to be done under new basic physical assumptions. The actual progress in the description of hadronic collision processes may exist only if the distribution of different initial states will be specified on the basis of impact parameter values of colliding particles and the dependence of collision probability on this parameter will be established, without limiting corresponding conclusions by the assumption of optical theorem validity from the very beginning.

    Comments:
    16 pages. arXiv admin note: substantial text overlap with arXiv:1403.1809
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1502.00468 [pdf]
    3 citations
  3. 08

    [Submitted on 2 Feb 2015] (cross-list from nucl-ex)

    Event-by-event mean p_T fluctuations in pp and Pb-Pb collisions at the LHC

    S. T. Heckel (for the ALICE Collaboration)🇩🇪

    The ALICE detector at the LHC is used to study the properties of the Quark-Gluon Plasma produced in heavy-ion collisions. As a reference measurement, also the analysis of proton-proton (pp) collisions is very important. In the study presented here, event-by-event fluctuations of the mean transverse momentum are analysed in pp collisions at sqrt(s) = 0.9, 2.76 and 7 TeV, and Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV as a function of the charged-particle multiplicity. In both systems, dynamical fluctuations beyond the statistical expectation are observed. In pp collisions, no significant dependence on collision energy is found, even in comparison to inclusive results at much lower collision energies. Likewise, central A-A collisions show only little dependence on collision energy. The multiplicity dependence observed in peripheral Pb-Pb data is in agreement with that in pp collisions. Going to more central Pb-Pb collisions, a clear deviation from this trend is found, reaching a significant reduction of the fluctuations in most central collisions. Comparisons to Monte Carlo event generators show good agreement in pp, but rather large differences in Pb-Pb collisions.

    Comments:
    6 pages, 7 figures, proceedings to the XLIV International Symposium on Multiparticle Dynamics (ISMD) 2014, Bologna, Italy
    Subjects:
    Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1502.00537 [pdf]
    EPJ Web Conf.(2015)·9 citations
  4. 09

    [Submitted on 2 Feb 2015] (cross-list from hep-lat)

    Multichannel one-to-two transition amplitudes in a finite volume

    Raúl A. Briceño🇺🇸 · Maxwell T. Hansen🇩🇪 · André Walker-Loud🇺🇸

    We derive a model-independent expression for finite-volume matrix elements. Specifically, we present a relativistic, non-perturbative analysis of the matrix element of an external current between a one-scalar in-state and a two-scalar out-state. Our result, which is valid for energies below higher-particle inelastic thresholds, generalizes the Lellouch-Luscher formula in two ways: we allow the external current to inject arbitrary momentum into the system and we allow for the final state to be composed an arbitrary number of strongly coupled two-particle states with arbitrary partial waves (including partial-wave mixing induced by the volume). We also illustrate how our general result can be applied to some key examples, such as heavy meson decays and meson photo production. Finally, we point out complications that arise involving unstable resonance states, such as when staggered or mixed-action/partially-quenched calculations are performed.

    Comments:
    Contribution to The 32nd International Symposium on Lattice Field Theory, 23-28 June, 2014, Columbia University New York, NY
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1502.00540 [pdf]
    PoS(2015)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE