PaperPanorama
FAQ

Nuclear Theory·nucl-th

Friday·March 13, 2015

10 papers—4 primary·6 cross-listed

All10Primary4Cross-lists6
  1. 05

    [Submitted on 11 Mar 2015] (cross-list from hep-ph)

    Light stops, blind spots, and isospin violation in the MSSM

    Andreas Crivellin🇨🇭 · Martin Hoferichter🇩🇪 · Massimiliano Procura🇦🇹 · Lewis C. Tunstall🇨🇭

    In the framework of the MSSM, we examine several simplified models where only a few superpartners are light. This allows us to study WIMP--nucleus scattering in terms of a handful of MSSM parameters and thereby scrutinize their impact on dark matter direct-detection experiments. Focusing on spin-independent WIMP--nucleon scattering, we derive simplified, analytic expressions for the Wilson coefficients associated with Higgs and squark exchange. We utilize these results to study the complementarity of constraints due to direct-detection, flavor, and collider experiments. We also identify parameter configurations that produce (almost) vanishing cross sections. In the proximity of these so-called blind spots, we find that the amount of isospin violation may be much larger than typically expected in the MSSM. This feature is a generic property of parameter regions where cross sections are suppressed, and highlights the importance of a careful analysis of the nucleon matrix elements and the associated hadronic uncertainties. This becomes especially relevant once the increased sensitivity of future direct-detection experiments corners the MSSM into these regions of parameter space.

    Comments:
    38 pages, 15 figures. v2: expanded text in Sec. 3 concerning relic density and (g-2)_mu constraints, clarified text on isospin violation. Fig. 1 is new, minor changes to Figs. 3,4,10. References added, journal version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Nuclear Theory (nucl-th)
    arXiv:
    1503.03478 [pdf]
    JHEP(2015)·62 citations
  2. 06

    [Submitted on 11 Mar 2015] (cross-list from hep-ph)

    Anisotropic Propagator for the Goldstone Modes in Color-flavor Locked Phase in the Presence of a Magnetic Field

    Srimoyee Sen🇺🇸

    We consider the phase diagram of QCD at very high baryon density and at zero temperature in the presence of a strong magnetic field. The state of matter at such high densities and low temperatures is believed to be a phase known as the color-flavor locked phase which breaks color and electromagnetic gauge invariance leaving a linear combination of them unbroken. Of the 9 quarks (three flavors and three colors), five are neutral under this unbroken generator and four are oppositely charged. In the presence of a magnetic field corresponding to the unbroken generator however, the properties of the condensate changes and a new phase known as the magnetic color flavor locked (MCFL)phase is realized. This phase breaks some of the color-flavor symmetry of the Lagrangian spontaneously, giving rise to 6 Goldstone modes, 5 of which are pseudo Goldstone modes. These Goldstone modes are composed of excitations that correspond to both neutral quarks and charged quarks. Hence it is natural to expect that the propagators of these Goldstone modes get affected in the presence of a magnetic field and their speed becomes considerably anisotropic. Although this anisotropy is self-evident from symmetry arguments, it has not been quantified yet. We calculate this anisotropy in the speed of the Goldstone modes using an NJL model type of interaction between the quarks and comment on the impact of such anisotropic modes on the transport properties of the MCFL phase.

    Comments:
    3 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1503.03484 [pdf]
    PRD(2015)·2 citations
  3. 07

    [Submitted on 11 Mar 2015] (cross-list from hep-ph)

    Realistic estimate of valence transversity distributions from inclusive dihadron production

    Marco Radici🇮🇹 · A. Courtoy🇧🇪 · Alessandro Bacchetta🇮🇹 · Marco Guagnelli🇮🇹

    We present an updated extraction of the transversity parton distribution based on the analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets in collinear factorization. Data for proton and deuteron targets make it possible to perform a flavor separation of the valence components of the transversity distribution, using di-hadron fragmentation functions taken from the semi-inclusive production of two pion pairs in back-to-back jets in e+e- annihilation. The e+e- data from Belle have been reanalyzed using the replica method and a more realistic estimate of the uncertainties on the chiral-odd interference fragmentation function has been obtained. Then, the transversity distribution has been extracted by using the most recent and more precise COMPASS data for deep-inelastic scattering off proton targets. Our results represent the most accurate estimate of the uncertainties on the valence components of the transversity distribution currently available.

    Comments:
    24 pages, 11 figures of which 7 have two panels; figs. 8a,8b,9a,9b updated with latest results from Ref.[5]; JHEP style file provided
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1503.03495 [pdf]
    JHEP(2015)·151 citations
  4. 08

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

    Spectroscopy of -nucleus bound states at GSI and FAIR --- very preliminary results and future prospects ---

    H. Fujioka🇯🇵 · Y. Ayyad🇯🇵 · J. Benlliure🇪🇸 · K.-T. Brinkmann🇩🇪 · S.Friedrich🇩🇪 · H. Geissel🇩🇪 · J. Gellanki🇳🇱 · C. Guo🇨🇳 · E. Gutz🇩🇪 · E. Haettner🇩🇪 · M.N. Harakeh🇳🇱 · R.S. Hayano🇯🇵 and 42 other authors

    The possible existence of \eta'-nucleus bound states has been put forward through theoretical and experimental studies. It is strongly related to the \eta' mass at finite density, which is expected to be reduced because of the interplay between the anomaly and partial restoration of chiral symmetry. The investigation of the C(p,d) reaction at GSI and FAIR, as well as an overview of the experimental program at GSI and future plans at FAIR are discussed.

    Comments:
    7 pages, 3 figures; talk at the International Conference on Exotic Atoms and Related Topics (EXA2014), Vienna, Austria, 15-19 September 2014. in Hyperfine Interactions (2015)
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1503.03566 [pdf]
    Hyperfine Interact.(2015)·10 citations
  5. 09

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

    Rapidity dependence of elliptic and triangular flow in proton-nucleus collisions from collective dynamics

    Piotr Bozek🇵🇱 · Adam Bzdak🇵🇱 · Guo-Liang Ma🇨🇳

    The rapidity dependence of elliptic, , and triangular, , flow coefficients in proton-nucleus (p+A) collisions is predicted in hydrodynamics and in a multi-phase transport model (AMPT). We find that () on a nucleus side is significantly larger than on a proton side and the ratio between the two, , weekly depends on the transverse momentum of produced particles.

    Comments:
    6 pages, 8 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1503.03655 [pdf]
    PLB(2015)·64 citations
  6. 10

    [Submitted on 12 Mar 2015] (cross-list from astro-ph.HE)

    High-mass twins & resolution of the reconfinement, masquerade and hyperon puzzles of compact star interiors

    David Blaschke🇷🇺 · D. E. Alvarez-Castillo🇷🇺

    We aim at contributing to the resolution of three of the fundamental puzzles related to the still unsolved problem of the structure of the dense core of compact stars (CS): (i) the hyperon puzzle: how to reconcile pulsar masses of M with the hyperon softening of the equation of state (EoS); (ii) the masquerade problem: modern EoS for cold, high density hadronic and quark matter are almost identical; and (iii) the reconfinement puzzle: what to do when after a deconfinement transition the hadronic EoS becomes favorable again? We show that taking into account the compositeness of baryons (by excluded volume and/or quark Pauli blocking) on the hadronic side and confining and stiffening effects on the quark matter side results in an early phase transition to quark matter with sufficient stiffening at high densities which removes all three present-day puzzles of CS interiors. Moreover, in this new class of EoS for hybrid CS falls the interesting case of a strong first order phase transition which results in the observable high mass twin star phenomenon, an astrophysical observation of a critical endpoint in the QCD phase diagram.

    Comments:
    6 pages, 4 figures, prepared for the Proceedings of the Conference "XIth Quark Confinement and the Hadron Spectrum", September 8 to 12, Saint-Petersburg State University, Russia
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1503.03834 [pdf]
    AIP Conf.Proc.(2016)·37 citations

Affiliations

first authorsco-authorsvia INSPIRE