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Nuclear Theory·nucl-th

Wednesday·January 28, 2015

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 06

    Gluon effects on the equation of state of color superconducting strange stars

    E. J. Ferrer🇺🇸 · V. de la Incera🇺🇸 · L. Paulucci🇧🇷

    Compact astrophysical objects are a window for the study of strongly interacting nuclear matter given the conditions in their interiors, which are not reproduced in a laboratory environment. Much has been debated about their composition with possibilities ranging from a simple mixture of mostly protons and neutrons to deconfined quark matter. Recent observations on the mass of two pulsars, PSR J1614-2230 and PSR J0348+0432, have posed a great restriction on their composition, since the equation of state must be hard enough to support masses of about at least two solar masses. The onset of quarks tends to soften the equation of state, but it can get substantially stiffer since in the high-dense medium a repulsive vector interaction channel is opened. Nevertheless, we show that once gluon effects are considered, the equation of state of quark matter in the color-flavor-locked phase of color superconductivity becomes softer decreasing the maximum stellar mass that can be reached when not considering their influence. This may indicate that stars made entirely of color superconducting matter can only be favored to describe compact stars if the repulsive vector constant is high enough.

    ↳ hep-phastro-ph.SRnucl-thPRD(2015)·19 citations
  2. 07

    (In-)Significance of the Anomalous Magnetic Moment of Charged Fermions for the Equation of State of a Magnetized and Dense Medium

    E. J. Ferrer🇺🇸 · V de la Incera🇺🇸 · D. Manreza Paret🇨🇺 · A. Perez Martinez🇨🇺 · A. Sanchez🇲🇽

    We investigate the effects of the anomalous magnetic moment (AMM) in the equation of state (EoS) of a system of charged fermions at finite density in the presence of a magnetic field. In the region of strong magnetic fields (eB>m^2) the AMM is found from the one-loop fermion self-energy. In contrast to the weak-field AMM found by Schwinger, in the strong magnetic field region the AMM depends on the Landau level and decreases with it. The effects of the AMM in the EoS of a dense medium are investigated at strong and weak fields using the appropriate AMM expression for each case. In contrast with what has been reported in other works, we find that the AMM of charged fermions makes no significant contribution to the EoS at any field value.

    ↳ hep-phastro-ph.HEnucl-thPRD(2015)·89 citations
  3. 08

    Power counting for three-body decays of a near-threshold state

    Mohammad H. Alhakami🇬🇧 · Michael C. Birse (University of Manchester)🇬🇧

    We propose a new power counting for the effective field theory describing a near-threshold state with unstable constituents, such as the X(3872) meson. In this counting, the momenta of the heavy particles, the pion mass and the excitation energy of the unstable constituent -- the D* in the case of the X -- are treated as small scales, of order Q. The difference, delta, between the excitation energy of the D* and the pion mass is smaller than either by a factor ~20. We therefore assign delta an order Q^2 in our counting. This provides a consistent framework for a double expansion in both delta/m_pi and the ratio of m_pi to the high-energy scales in this system. It ensures that amplitudes have the correct behaviour at the three-body threshold. It allows us to derive, within an effective theory, various results which have previously been obtained using physically-motivated approximations.

    ↳ hep-phnucl-thPRD(2015)·14 citations
  4. 09

    2014 Update of the Discoveries of Nuclides

    M. Thoennessen

    The 2014 update of the discovery of nuclide project is presented. Only six new nuclides were observed for the first time in 2014 while the assignments of seventeen other nuclides were revised. In addition, for another fourteen nuclides the laboratories where they were discovered were reassigned.

    ↳ nucl-exnucl-thIJMPE(2015)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE