Nuclear Theory·nucl-th

Friday·September 18, 2015

13 papers—7 primary·6 cross-listed

01
Direct Urca processes involving singlet proton superfluidity in neutron star cooling
Yan Xu · Xiu Lin Huang · Xiao Jun Zhang · Tmurbagan Bao · Lin Xiao · Cun Bo Fan · Cheng Zhi Liu
A detailed description of the baryon direct Urca processes A: $n \to p + e + ν ˉ_{e}$ , B: $Λ \to p + e + ν ˉ_{e}$ , C: $Ξ^{-} \to Λ + e + ν ˉ_{e}$ related to the neutron star cooling is given in the relativistic mean field approximation.The contributions of the reactions B and C on the neutrino luminosity are calculated by means of the relativistic expressions of the neutrino energy losses.Our results show that the total neutrino luminosities of the reactions A, B, C within the mass range 1.603-2.067 $M_{⊙}$ (1.515-1.840 $M_{⊙}$ for TM1 model) for GM1 model are larger than the corresponding values for neutron stars in npe $μ$ matter. Although the hyperon direct Urca processes B and C reduce the neutrino emissivity of the reaction A, it illustrates the reactions B and C still make the total neutrino luminosity enhancement in the above mentioned areas.Furthermore, when we only consider the $^{1} S_{0}$ proton superfluidity in neutron star cooling, we find that although the neutrino emissivity of the reactions A and B is suppressed with the appearance of $^{1} S_{0}$ proton superfluidity, the total contribution of the reactions A, B, C can still quicken a massive neutron star cooling.These results could be used to help prove appearing hyperons in PSR J1614-2230 and J0348+0432 from neutron star cooling perspective.
nucl-thCommun.Theor.Phys.(2018)·5 citations
02
Deconfinement Phase Transition with External Magnetic Field in Friedberg-Lee Model
Shijun Mao🇨🇳
The deconfinement phase transition with external magnetic field is investigated in the Friedberg-Lee model. In the frame of functional renormalization group, we extend the often used potential expansion method for continuous phase transitions to the first-order phase transition in the model. By solving the flow equations we find that, the magnetic field displays a catalysis effect and it becomes more difficult to break through the confinement in hot and dense medium.
nucl-thChin.Phys.Lett.(2016)·2 citations
03
Phase space factors and half-life predictions for Majoron emitting $β^{-} β^{-}$ decay
J. Kotila🇫🇮 · J. Barea🇨🇱 · F. Iachello🇺🇸
A complete calculation of phase space factors (PSF) for Majoron emitting $0 ν β^{-} β^{-}$ decay modes is presented. The calculation makes use of exact Dirac wave functions with finite nuclear size and electron screening and includes life-times, single electron spectra, summed electron spectra, and angular electron correlations. Combining these results with recent interacting boson nuclear matrix elements (NME) we make half-life predictions for the the ordinary Majoron decay (spectral index $n$ =1). Furthermore, comparing theoretical predictions with the obtained experimental lower bounds for this decay mode we are able to set limits on the effective Majoron-neutrino coupling constant $⟨ g_{ee}^{M} ⟩$ .
nucl-thPRC(2015)·51 citations
04
Neutrinoless double positron decay and positron emitting electron capture in the interacting boson model
J. Barea🇨🇱 · J. Kotila🇺🇸 · F. Iachello🇺🇸
Neutrinoless double- $β$ decay is of fundamental importance for determining the neutrino mass. Although double electron ( $β^{-} β^{-}$ ) decay is the most promising mode, in very recent years interest in double positron ( $β^{+} β^{+}$ ) decay, positron emitting electron capture ( $E C β^{+}$ ), and double electron capture ( $E C E C$ ) has been renewed. We present here results of a calculation of nuclear matrix elements for neutrinoless double- $β^{+}$ decay and positron emitting electron capture within the framework of the microscopic interacting boson model (IBM-2) for $^{58}$ Ni, $^{64}$ Zn, $^{78}$ Kr, $^{96}$ Ru, $^{106}$ Cd, $^{124}$ Xe, $^{130}$ Ba, and $^{136}$ Ce decay. By combining these with a calculation of phase space factors we calculate expected half-lives.
nucl-thPRC(2013)·35 citations
05
Production of antimatter $^{5, 6}$ Li nuclei in central Au+Au collisions at $s_{N N} = 200$ GeV
Kai-Jia Sun🇨🇳 · Lie-Wen Chen🇨🇳
Combining the covariant coalescence model and a blast-wave-like analytical parametrization for (anti-)nucleon phase-space freezeout configuration, we explore light (anti-)nucleus production in central Au+Au collisions at $s_{N N} = 200$ GeV. Using the nucleon freezeout configuration (denoted by FO1) determined from the measured spectra of protons (p), deutrons (d) and $^{3}$ He, we find the predicted yield of $^{4}$ He is significantly smaller than the experimental data. We show this disagreement can be removed by using a nucleon freezeout configuration (denoted by FO2) in which the nucleons are assumed to freeze out earlier than those in FO1 to effectively consider the effect of large binding energy value of $^{4}$ He. Assuming the binding energy effect also exists for the production of $^{5} Li$ , $^{5} Li$ , $^{6} Li$ and $^{6} Li$ due to their similar binding energy values as $^{4}$ He, we find the yields of these heavier (anti-)nuclei can be enhanced by a factor of about one order, implying that although the stable (anti-) $^{6}$ Li nucleus is unlikely to be observed, the unstable (anti-) $^{5}$ Li nucleus could be produced in observable abundance in Au+Au collisions at $s_{N N} = 200$ GeV where it may be identified through the p- $^{4} He$ ( $p$ - $^{4} He$ ) invariant mass spectrum. The future experimental measurement on (anti-) $^{5} Li$ would be very useful to understand the production mechanism of heavier antimatter.
nucl-thastro-ph.COhep-phnucl-exPLB(2015)·40 citations
06
Reference calculations for subthreshold $Ξ$ production
Boris Tomasik🇨🇿 · Evgeni E Kolomeitsev🇸🇰
We present a minimal statistical model designed for the description of rare-hadron multiplicities in nucleus-nucleus collisions at energies below the threshold of the particle production in binary elementary collisions. Differences to more conventional canonical statistical model are explained. The minimal statistical model is applied to the description of multiplicity ratios involving $Ξ$ hyperons, which are measured by the HADES collaboration at GSI-SIS. It is argued that the HADES data cannot be reproduced by the model based on the statistical equilibrium and the strangeness conservation. The data remain underpredicted even when in-medium potentials acting on hadrons are taken into account. This hints to non-equilibrium production of the $Ξ$ hyperons and their continuous freeze-out.
nucl-thhep-phJ.Phys.Conf.Ser.(2016)·0 citations
07
Blast wave fits with resonances to $p_{t}$ spectra from nuclear collisions at the LHC
Ivan Melo🇸🇰 · Boris Tomasik🇸🇰
We report our results for the freeze-out temperature and transverse flow profile obtained from fits to hadronic spectra measured by the ALICE collaboration. The influence of resonance decays is important and cannot be simply accounted for without the inclusion of their decays into the fits.
nucl-thnucl-exJ.Phys.Conf.Ser.(2016)·5 citations
08
Kaon pair production in proton-nucleus collisions at 2.83 GeV kinetic energy
Yu.T. Kiselev🇷🇺 · M. Hartmann · A. Polyanskiy🇩🇪 · E.Ya. Paryev🇷🇺 · S. Barsov🇷🇺 · M. Buescher · S. Dymov🇷🇺 · R. Gebel🇯🇵 · V. Hejny🇯🇵 · A. Kacharava🇯🇵 · I. Keshelashvili🇯🇵 · B. Lorentz🇯🇵 and 14 other authors
The production of non-phi K+K- pairs by protons of 2.83 GeV kinetic energy on C, Cu, Ag, and Au targets has been investigated using the COSY-ANKE magnetic spectrometer. The K- momentum dependence of the differential cross section has been measured at small angles over the 0.2--0.9 GeV/c range. The comparison of the data with detailed model calculations indicates an attractive K- -nucleus potential of about -60 MeV at normal nuclear matter density at a mean momentum of 0.5 GeV/c. However, this approach has difficulty in reproducing the smallness of the observed cross sections at low K- momenta.
↳ nucl-exnucl-thPRC(2015)·6 citations
09
Hydrodynamics, resurgence and trans-asymptotics
Gokce Basar🇺🇸 · Gerald V. Dunne🇺🇸
The second-order hydrodynamical description of a homogeneous conformal plasma that undergoes a boost- invariant expansion is given by a single nonlinear ordinary differential equation, whose resurgent asymptotic properties we study, developing further the recent work of Heller and Spalinski [Phys. Rev. Lett. 115, 072501 (2015)]. Resurgence clearly identifies the non-hydrodynamic modes that are exponentially suppressed at late times, analogous to the quasi-normal-modes in gravitational language, organizing these modes in terms of a trans-series expansion. These modes are analogs of instantons in semi-classical expansions, where the damping rate plays the role of the instanton action. We show that this system displays the generic features of resurgence, with explicit quantitative relations between the fluctuations about different orders of these non-hydrodynamic modes. The imaginary part of the trans-series parameter is identified with the Stokes constant, and the real part with the freedom associated with initial conditions.
↳ hep-thmath-phmath.MPnucl-thPRD(2015)·94 citations
10
Quenching of inclusive and tagged b-jets at the LHC
Hongxi Xing🇺🇸 · Jinrui Huang🇺🇸 · Zhong-Bo Kang🇺🇸 · Ivan Vitev🇺🇸
We present theoretical predictions for the nuclear-induced attenuation of the differential cross sections for inclusive and tagged b-jet production in heavy ion collisions at the LHC. We find that for inclusive b-jet production at high transverse momentum the mass effects are negligible, and that the attenuation is comparable to the one observed for light jets. On the other hand, for isolated-photon and B-meson-tagged b-jets the sample of events with heavy quarks produced at the early stages of the collision is greatly enhanced. Thus, these tagged b-jet final-states have a much more direct connection to the physics of b-quark energy loss. We present theoretical predictions for the quenching of such tagged b-jet events at the LHC and the QGP-induced modification of the related momentum imbalance and asymmetry. We demonstrate that these tagged processes can be used to accurately study the physics of heavy quark production and propagation in dense QCD matter.
↳ hep-phnucl-thNucl.Part.Phys.Proc.(2016)·3 citations
11
Excitation function Analysis for Charmonium Production in Heavy-Ion Collisions
Kai Zhou🇩🇪
Both color screening and regeneration are hot medium effects on charmonium production in heavy ion collisions. While they affect in an opposite way the charmonium yield, their competition in transverse dynamics bring sensitivity to the ratio of averaged transverse momentum suqare for charmonium, which thus can reveal more nature of the QCD medium created from the collisions. We make an excitation analysis based on transport approach to illustrate such a picuture.
↳ hep-phnucl-thJ.Phys.Conf.Ser.(2016)·0 citations
12
Proof of Factorization of $J /Ψ$ Production in Non-Equilibrium QCD at RHIC and LHC
Gouranga C. Nayak🇺🇸
$J / ψ$ suppression/production is one of the main signature of quark-gluon plasma detection at RHIC and LHC. In order to study $j / ψ$ suppression/production in high energy heavy-ion collisions at RHIC and LHC, one needs to prove the factorization theorem of $j / ψ$ production in non-equilibrium QCD medium, otherwise one will predict infinite cross section of $j / ψ$ . In this paper we prove factorization theorem of $j / ψ$ production in non-equilibrium QCD at RHIC and LHC at all order in coupling constant.
↳ hep-phnucl-th1 citation
13
Dependence of elastic hadron collisions on impact parameter
Jiri Prochazka🇨🇿 · Milos V. Lokajicek🇨🇿 · Vojtech Kundrat🇨🇿
Elastic proton-proton collisions represent probably the greatest ensemble of available measured data, the analysis of which may provide large amount of new physical results concerning fundamental particles. It is, however, necessary to analyze first some conclusions concerning pp collisions and their interpretations differing fundamentally from our common macroscopic experience. It has been argued, e.g., that elastic hadron collisions have been more central than inelastic ones, even if any explanation of the existence of so different process, i.e., elastic and inelastic (with hundreds of secondary particles) collisions, under the same conditions has not been given until now. The given conclusion has been based on a greater number of simplifying mathematical assumptions (done already in earlier calculations), without their influence on physical interpretation being analyzed and entitled; the corresponding influence has started to be studied in the approach based on eikonal model. The possibility of peripheral interpretation of elastic collisions will be demonstrated and corresponding results summarized. The arguments will be given why no preference may be given to the mentioned centrality against the standard peripheral behaviour. The corresponding discussion of contemporary description of elastic hadronic collision in dependence on impact parameter will be summarized and the justification of some important assumptions will be considered.
↳ hep-phhep-thnucl-thEur.Phys.J.Plus(2016)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE