PaperPanorama
FAQ

Nuclear Theory·nucl-th

Monday·October 5, 2015

12 papers—8 primary·4 cross-listed

All12Primary8Cross-lists4
  1. 09

    [Submitted on 1 Oct 2015] (cross-list from astro-ph.SR)

    Pinning down the superfluid and measuring masses using pulsar glitches

    Wynn C. G. Ho · Cristobal M. Espinoza · Danai Antonopoulou · Nils Andersson

    Pulsars are known for their superb timing precision, although glitches can interrupt the regular timing behavior when the stars are young. These glitches are thought to be caused by interactions between normal and superfluid matter in the crust of the star. However, glitching pulsars such as Vela have been shown to require a superfluid reservoir that greatly exceeds that available in the crust. We examine a model in which glitches tap the superfluid in the core. We test a variety of theoretical superfluid models against the most recent glitch data and find that only one model can successfully explain up to 45 years of observational data. We develop a new technique for combining radio and X-ray data to measure pulsar masses, thereby demonstrating how current and future telescopes can probe fundamental physics such as superfluidity near nuclear saturation.

    Comments:
    5 pages, 3 figures; published in Science Advances on 2 Oct 2015
    Subjects:
    Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1510.00395 [pdf]
    Science Adv. 1, e1500578 (2015)·65 citations
  2. 10

    [Submitted on 1 Oct 2015] (cross-list from astro-ph.CO)

    Majorana Neutrino Magnetic Moment and Neutrino Decoupling in Big Bang Nucleosynthesis

    N. Vassh (Wisconsin U., Madison)🇺🇸 · E. Grohs ( Michigan U.)🇺🇸 · A.B. Balantekin (Wisconsin U., Madison)🇺🇸 · G.M. Fuller (UC, San Diego)🇺🇸

    We examine the physics of the early universe when Majorana neutrinos (electron neutrino, muon neutrino, tau neutrino) possess transition magnetic moments. These extra couplings beyond the usual weak interaction couplings alter the way neutrinos decouple from the plasma of electrons/positrons and photons. We calculate how transition magnetic moment couplings modify neutrino decoupling temperatures, and then use a full weak, strong, and electromagnetic reaction network to compute corresponding changes in Big Bang Nucleosynthesis abundance yields. We find that light element abundances and other cosmological parameters are sensitive to magnetic couplings on the order of 10^{-10} Bohr magnetons. Given the recent analysis of sub-MeV Borexino data which constrains Majorana moments to the order of 10^{-11} Bohr magnetons or less, we find that changes in cosmological parameters from magnetic contributions to neutrino decoupling temperatures are below the level of upcoming precision observations.

    Comments:
    19 pages, 9 figures
    Subjects:
    Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1510.00428 [pdf]
    PRD(2015)·31 citations
  3. 11

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

    Massive Yang-Mills for Vector and Axial-Vector Spectral Functions at Finite Temperature

    Paul M. Hohler🇺🇸 · Ralf Rapp🇺🇸

    The hadronic mechanism which leads to chiral symmetry restoration is explored in the context of the rho-pi-a_1 system using Massive Yang-Mills, a hadronic effective theory which governs their microscopic interactions. In this approach, vector and axial-vector mesons are implemented as gauge bosons of a local chiral gauge group. We have previously shown that this model can describe the experimentally measured vector and axial-vector spectral functions in vacuum. Here, we carry the analysis to finite temperatures by evaluating medium effects in a pion gas and calculating thermal spectral functions. We find that the spectral peaks in both channels broaden along with a noticeable downward mass shift in the a_1 spectral peak and negligible movement of the rho peak. The approach toward spectral function degeneracy is accompanied by a reduction of chiral order parameters, i.e., the pion decay constant and scalar condensate. Our findings suggest a mechanism where the chiral mass splitting induced in vacuum is burned off. We explore this mechanism and identify future investigations which can further test it.

    Comments:
    28 pages, 24 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1510.00454 [pdf]
    Annals Phys.(2016)·18 citations
  4. 12

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

    The light-front energy-momentum tensor

    Cédric Lorcé (CPHT, Ecole Polytechnique)🇧🇪

    We present the first complete parametrization for the matrix elements of the generic light-front gauge-invariant energy-momentum tensor, derive the expressions giving separately the spin and orbital angular momentum of quarks and gluons as probed in high-energy scattering experiments, and discuss the relations with two-parton generalized and transverse-momentum dependent distributions. As a by-product, we recovered the Burkardt sum rule, clarified its physical meaning and obtained similar new sum rules for higher-twist distributions.

    Comments:
    10 pages, contribution to the proceedings of the QCD Evolution 2015 Workshop, May 26-30, Jefferson Lab, Newport News, Virginia,USA
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1510.00514 [pdf]
    PoS(2015)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE