Nuclear Theory·nucl-th
11 papers—4 primary·7 cross-listed
D. A. Bryman🇨🇦 · R. Shrock🇺🇸
Improved upper bounds are presented on the coupling of an electron to a sterile neutrino from analyses of data on nuclear and particle decays, including superallowed nuclear beta decays, the ratios , , , and decay, covering the mass range from MeV to GeV.
Wynn C.G. Ho🇺🇸 · M.J.P. Wijngaarden🇬🇧 · Philip Chang🇺🇸 · Craig O. Heinke🇨🇦 · Dany Page🇲🇽 · Mikhail Beznogov🇲🇽 · Daniel J. Patnaude🇺🇸
The study of how neutron stars cool over time can provide invaluable insights into fundamental physics such as the nuclear equation of state and superconductivity and superfluidity. A critical relation in neutron star cooling is the one between observed surface temperature and interior temperature. This relation is determined by the composition of the neutron star envelope and can be influenced by the process of diffusive nuclear burning (DNB). We calculate models of envelopes that include DNB and find that DNB can lead to a rapidly changing envelope composition which can be relevant for understanding the long-term cooling behavior of neutron stars. We also report on analysis of the latest temperature measurements of the young neutron star in the Cassiopeia A supernova remnant. The 13 Chandra observations over 18 years show that the neutron star's temperature is decreasing at a rate of 2-3 percent per decade, and this rapid cooling can be explained by the presence of a proton superconductor and neutron superfluid in the core of the star.
D. G. Ireland🇬🇧 · M. Döring🇺🇸 · D. I. Glazier🇬🇧 · J. Haidenbauer🇩🇪 · M. Mai🇺🇸 · R. Murray-Smith🇬🇧 · D. Rönchen🇩🇪
The weak decay parameter of the is an important quantity for the extraction of polarization observables in various experiments. Moreover, in combination with from decay it provides a measure for matter-antimatter asymmetry. The weak decay parameter also affects the decay parameters of the and baryons and, in general, any quantity in which the polarization of the is relevant. The recently reported value by the BESIII collaboration of is significantly larger than the previous PDG value of that had been accepted and used for over 40 years. In this work we make an independent estimate of , using an extensive set of polarization data measured in kaon photoproduction in the baryon resonance region and constraints set by spin algebra. The obtained value is 0.721(6)(5). The result is corroborated by multiple statistical tests as well as a modern phenomenological model, showing that our new value yields the best description of the data in question. Our analysis supports the new BESIII finding that is significantly larger than the previous PDG value. Any experimental quantity relying on the value of should therefore be re-considered.
Elmar P. Biernat🇵🇹 · Franz Gross🇺🇸 · M. T. Peña🇵🇹 · Alfred Stadler🇵🇹 · Sofia Leitão🇵🇹
We present results for the quark mass function in Minkowski space calculated from an interaction kernel that consists of an effective one-gluon-exchange and a constant interaction. We analyze the gauge dependence of our results and compare them in the spacelike region to the available lattice QCD data.
Gergely Gábor Barnaföldi🇭🇺 · Vakhtang Gogokhia🇭🇺
We convincingly argue that the true dynamical and gauge structures of the QCD ground state are much more complicated than its Lagrangian exact gauge symmetry supposes to be. The dynamical source of these complications has been identified with the tadpole/seagull term, which renormalized version called, {\sl the mass gap}. It is explicitly present in the full gluon self-energy. The true dynamical role of the mass gap was hidden in the QCD ground state. To disclose it the splintering between the transverse conditions for the full gluon self-energy and its subtracted counterpart has been derived. We have established the equation of motion for the full gluon propagator on account of the mass gap. It allows to fix the dynamical and gauge structures of the full gluon propagator with a newly-derived generalized gauge. It is uniquely given as a function of the gluon momentum. All this makes it possible to present novel non-perturbative analytical approach to QCD, which we call the mass gap approach. It extends the mass gap concept to be accounted for the QCD ground state as well. We have found the general non-perturbative solution for the full gluon propagator with exactly defined finite gluon pole mass, and it is different from the excitations with the effective gluon masses. Despite the exact gauge symmetry is broken in the ground state, the renormalizability of the theory is not affected due to the important role of the Slavnov-Taylor identity in the renormalization beyond the perturbation theory. For this the non-perturbative multiplicative renormalization program for the full massive gluon propagator has been formulated. Our approach does not allow the massive gluons to be the mass-shell objects, and thus prevents them to appear as physical states at large distances (confinement of massive gluons).
Yu-Feng Li🇨🇳 · Di Zhang🇨🇳
Validation of the effective conversion method in the reactor antineutrino flux calculation is examined using the \textit{ab initio} calculation of the electron and antineutrino spectra from the state-of-the-art nuclear database. It turns out that neglecting the shape variation of beta decay branches between the allowed and forbidden transitions would induce significant bias in the total inverse-beta-decay yields and energy spectral distributions. We propose a new realization of the conversion method with both the allowed and forbidden virtual branches, and apply it to both the \textit{simulated} data from the nuclear database and \textit{real} data from the fission measurements at ILL by virtue of statistical properties of the allowed and forbidden decays in the database. Two kinds of dominant uncertainty sources are identified and it turns out that the new realization of the conversion calculation can largely reduce the rate and spectral bias and thus present a reliable prediction of the antineutrino fluxes if accurate beta decay information is available in the high endpoint energy range.
Cyril Pitrou🇫🇷 · Maxim Pospelov🇨🇦
We compute radiative corrections to nuclear reaction rates that determine the outcome of the Big-Bang Nucleosynthesis (BBN). Any nuclear reaction producing a photon with an energy above must be supplemented by the corresponding reaction where the final state photon is replaced by an electron-positron pair. We find that pair production brings a typical enhancement to photon emission rates, resulting in a similar size corrections to elemental abundances. The exception is abundance, which is insensitive to the small changes in the nuclear reaction rates. We also investigate the effect of vacuum polarisation on the Coulomb barrier, which brings a small extra correction when reaction rates are extrapolated from the measured energies to the BBN Gamow peak energies.
first authorsco-authorsvia INSPIRE