Nuclear Theory·nucl-th

Wednesday·November 1, 2017

8 papers—1 primary·7 cross-listed

02
Heavy Nuclei as Thermal Insulation for Proto-Neutron Stars
Ken'ichiro Nakazato🇯🇵 · Hideyuki Suzuki🇯🇵 · Hajime Togashi🇯🇵
A proto-neutron star (PNS) is a newly formed compact object in a core collapse supernova. In this Letter, the neutrino emission from the cooling process of a PNS is investigated using two types of nuclear equation of state (EOS). It is found that the neutrino signal is mainly determined by the high-density EOS. The neutrino luminosity and mean energy are higher and the cooling time scale is longer for the softer EOS. Meanwhile, the neutrino mean energy and the cooling time scale are also affected by the low-density EOS because of the difference in the population of heavy nuclei. Heavy nuclei have a large scattering cross section with neutrinos owing to the coherent effects and act as thermal insulation near the surface of a PNS. The neutrino mean energy is higher and the cooling time scale is longer for an EOS with a large symmetry energy at low densities, namely a small density derivative coefficient of the symmetry energy, $L$ .
↳ astro-ph.HEhep-phnucl-thPRC(2018)·34 citations
03
One percent determination of the primordial deuterium abundance
Ryan Cooke (1) · Max Pettini (2,3) · Charles C. Steidel (4) ((1) Centre for Extragalactic Astronomy, Durham University, (2) Institute of Astronomy, University of Cambridge, (3) Kavli Institute for Cosmology, University of Cambridge, (4) California Institute of Technology)
We report a reanalysis of a near-pristine absorption system, located at a redshift z_abs=2.52564 toward the quasar Q1243+307, based on the combination of archival and new data obtained with the HIRES echelle spectrograph on the Keck telescope. This absorption system, which has an oxygen abundance [O/H]=-2.769+/-0.028 (~1/600 of the Solar abundance), is among the lowest metallicity systems currently known where a precise measurement of the deuterium abundance is afforded. Our detailed analysis of this system concludes, on the basis of eight D I absorption lines, that the deuterium abundance of this gas cloud is log_10(D/H) = -4.622+/-0.015, which is in very good agreement with the results previously reported by Kirkman et al. (2003), but with an improvement on the precision of this single measurement by a factor of ~3.5. Combining this new estimate with our previous sample of six high precision and homogeneously analyzed D/H measurements, we deduce that the primordial deuterium abundance is log_10(D/H)_P = -4.5974+/-0.0052 or, expressed as a linear quantity, (D/H)_P = (2.527+/-0.030)x10^-5; this value corresponds to a one percent determination of the primordial deuterium abundance. Combining our result with a BBN calculation that uses the latest nuclear physics input, we find that the baryon density derived from BBN agrees to within 2 sigma of the latest results from the Planck CMB data.
↳ astro-ph.COastro-ph.GAnucl-thApJ(2018)·631 citations
04
Is Seniority a Partial Dynamic Symmetry in the First $ν g_{9/2}$ Shell?
A.I. Morales🇮🇹 · G. Benzoni🇮🇹 · H. Watanabe🇨🇳 · G. de Angelis🇮🇹 · S. Nishimura🇯🇵 · L. Coraggio🇮🇹 · A. Gargano🇮🇹 · N. Itaco🇮🇹 · T. Otsuka🇯🇵 · Y. Tsunoda🇯🇵 · P. Van Isacker🇫🇷 · F. Browne🇬🇧 and 51 other authors
The low-lying structures of the midshell $ν g_{9/2}$ Ni isotopes $^{72}$ Ni and $^{74}$ Ni have been investigated at the RIBF facility in RIKEN within the EURICA collaboration. Previously unobserved low-lying states were accessed for the first time following $β$ decay of the mother nuclei $^{72}$ Co and $^{74}$ Co. As a result, we provide a complete picture in terms of the seniority scheme up to the first $(8^{+})$ levels for both nuclei. The experimental results are compared to shell-model calculations in order to define to what extent the seniority quantum number is preserved in the first neutron $g_{9/2}$ shell. We find that the disappearance of the seniority isomerism in the $(8_{1}^{+})$ states can be explained by a lowering of the seniority-four $(6^{+})$ levels as predicted years ago. For $^{74}$ Ni, the internal de-excitation pattern of the newly observed $(6_{2}^{+})$ state supports a restoration of the normal seniority ordering up to spin $J = 4$ . This property, unexplained by the shell-model calculations, is in agreement with a dominance of the single-particle spherical regime near $^{78}$ Ni.
↳ nucl-exnucl-thPLB(2018)·25 citations
05
Few-body techniques using momentum space for bound and continuum states
M. T. Yamashita
These notes were written for a set of three lectures given in a school at the Max Planck Institute for the Physics of Complex Systems in October/2017 before the workshop "Critical Stability of Quantum Few-Body Systems". These lectures are primarily dedicated to the students and represent a very idiosyncratic vision of the author, mainly in the last part of the text related to applications. These notes are only a tentative to show a technique, among many others, to solve problems in a very rich area of the contemporary physics - the Few-Body Physics - many times unknown by a considerable part of the students.
↳ quant-phcond-mat.quant-gasnucl-thFew Body Syst.(2018)·1 citation
06
A study of $ρ - ω$ mixing in resonance chiral theory
Yun-Hua Chen🇨🇳 · De-Liang Yao🇪🇸 · Han-Qing Zheng🇨🇳
The strong and electromagnetic corrections to $ρ - ω$ mixing are calculated using a SU(2) version of resonance chiral theory up to next-to-leading orders in $1/ N_{C}$ expansion, respectively. Up to our accuracy, the effect of the momentum dependence of $ρ - ω$ mixing is incorporated due to the inclusion of loop contributions. We analyze the impact of $ρ - ω$ mixing on the pion vector form factor by performing numerical fit to the data extracted from $e^{+} e^{-} \to π^{+} π^{-}$ and $τ \to ν_{τ} 2 π$ , while the decay width of $ω \to π^{+} π^{-}$ is taken into account as a constraint. It is found that the momentum dependence is significant in a good description of the experimental data. In addition, based on the fitted values of the involved parameters, we analyze the decay width of $ω \to π^{+} π^{-}$ , which turns out to be highly dominated by the $ρ - ω$ mixing effect.
↳ hep-phhep-exnucl-thCommun.Theor.Phys.(2018)·11 citations
07
New theoretical results in ultrarelativistic ultraperipheral lead-lead collisions
Mariola Klusek-Gawenda🇵🇱 · Antoni Szczurek🇵🇱
We study dilepton, proton-antiproton and diphoton production in ultraperipheral lead-lead collisions at $s_{NN}$ = 5.02 and 5.5 TeV. The nuclear calculations are based on equivalent photon approximation in the impact parameter space. For correct description of the $γ γ \to p p ˉ$ Belle data we include the proton-exchange, the $f_{2} (1270)$ and $f_{2} (1950)$ s-channel exchanges, as well as the handbag mechanism. For four muon production, we take into account electromagnetic (two-photon) double-scattering production and direct $γ γ$ production of four muons in one scattering. The cross sections for elementary $γ γ \to γ γ$ subprocess are calculated including three different mechanisms: box diagrams with leptons and quarks in the loops, a VDM-Regge contribution with virtual intermediate hadronic excitations of the photons and the two-gluon exchange contribution. We find that the cross section for elastic $γ γ$ scattering could be measured in the lead-lead collisions for the diphoton invariant mass up to $W_{γ γ} \approx$ 15 - 20 GeV. Our Standard Model predictions are compared with a recent ATLAS experimental result. We discuss results for PbPb $\to$ PbPb $μ^{+} μ^{-} μ^{+} μ^{-}$ , PbPb $\to$ PbPb $e^{+} e^{-} e^{+} e^{-}$ , PbPb $\to$ PbPb $p p ˉ$ and PbPb $\to$ PbPb $γ γ$ reactions at LHC energy.
↳ hep-phnucl-th0 citations
08
Neutrino propagation in binary neutron star mergers in presence of nonstandard interactions
Amélie Chatelain🇫🇷 · Maria Cristina Volpe🇫🇷
We explore the impact of nonstandard interactions on neutrino propagation in accretion disks around binary neutron star mergers remnants. We show flavor evolution can be significantly modified even for values of the nonstandard couplings well below current bounds. We demonstrate the occurrence of I resonances as synchronized MSW phenomena and show that intricate conversion patterns might appear depending on the nonstandard interaction parameters. We discuss the possible implications for nucleosynthesis.
↳ hep-phnucl-thPRD(2018)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE

Heavy Nuclei as Thermal Insulation for Proto-Neutron Stars

One percent determination of the primordial deuterium abundance

Is Seniority a Partial Dynamic Symmetry in the First νg9/2​ Shell?

Few-body techniques using momentum space for bound and continuum states

A study of ρ−ω mixing in resonance chiral theory

New theoretical results in ultrarelativistic ultraperipheral lead-lead collisions

Neutrino propagation in binary neutron star mergers in presence of nonstandard interactions

Affiliations

Is Seniority a Partial Dynamic Symmetry in the First $ν g_{9/2}$ Shell?

A study of $ρ - ω$ mixing in resonance chiral theory