Thu·Mar 10, 2016Thursday·March 10, 2016

1. 01*

   Isospin Mixing Reveals ${}^{30}$P($p,\gamma$)${}^{31}$S Resonance Influencing Nova Nucleosynthesis

   M. B. Bennett🇺🇸 · C. Wrede🇺🇸 · B. A. Brown🇺🇸 · S. N. Liddick🇺🇸 · D. Pérez-Loureiro🇺🇸 · D. W. Bardayan🇺🇸 · A. A. Chen🇨🇦 · K. A. Chipps🇺🇸 · C. Fry🇺🇸 · B. E. Glassman🇺🇸 · C. Langer🇺🇸 · N. R. Larson🇺🇸 and 12 other authors

   The thermonuclear ${}^{30}$P($p,\gamma$)${}^{31}$S reaction rate is critical for modeling the final elemental and isotopic abundances of ONe nova nucleosynthesis, which affect the calibration of proposed nova thermometers and the identification of presolar nova grains, respectively. Unfortunately, the rate of this reaction is essentially unconstrained experimentally, because the strengths of key ${}^{31}$S proton capture resonance states are not known, largely due to uncertainties in their spins and parities. Using the $\beta$ decay of ${}^{31}$Cl, we have observed the $\beta$-delayed $\gamma$ decay of a ${}^{31}$S state at $E_x=6390.2(7)$ keV, with a ${}^{30}$P($p,\gamma$)${}^{31}$S resonance energy of $E_r=259.3(8)$ keV, in the middle of the ${}^{30}$P($p,\gamma$)${}^{31}$S Gamow window for peak nova temperatures. This state exhibits isospin mixing with the nearby isobaric analog state (IAS) at $E_x=6279.0(6)$ keV, giving it an unambiguous spin and parity of $3/2^{+}$ and making it an important $l=0$ resonance for proton capture on ${}^{30}$P.

   nucl-exPRL(2016)·41 citations
2. 02*

   Centrality dependence of $\psi$(2S) suppression in p-Pb collisions at $\sqrt{{\text{s}}_{\mathrm{NN}}}$ = 5.02 TeV

   ALICE Collaboration

   The inclusive production of the $\psi$(2S) charmonium state was studied as a function of centrality in p-Pb collisions at the nucleon-nucleon center of mass energy $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV at the CERN LHC. The measurement was performed with the ALICE detector in the center of mass rapidity ranges $-4.46<y_{\mathrm{cms}}<-2.96$ and $2.03<y_{\mathrm{cms}}<3.53$, down to zero transverse momentum, by reconstructing the $\psi$(2S) decay to a muon pair. The $\psi$(2S) production cross section ${\sigma }_{\psi (2S)}$ is presented as a function of the collision centrality, which is estimated through the energy deposited in forward rapidity calorimeters. The relative strength of nuclear effects on the $\psi$(2S) and on the corresponding 1S charmonium state J/$\psi$ is then studied by means of the double ratio of cross sections $[{\sigma }_{\psi (2S)}/{\sigma }_{J/\psi }{]}_{\mathrm{pPb}}/[{\sigma }_{\psi (2S)}/{\sigma }_{J/\psi }{]}_{\mathrm{pp}}$ between p-Pb and pp collisions, and by the values of the nuclear modification factors for the two charmonium states. The results show a large suppression of $\psi$(2S) production relative to the J/$\psi$ at backward (negative) rapidity, corresponding to the flight direction of the Pb-nucleus, while at forward (positive) rapidity the suppressions of the two states are comparable. Finally, comparisons to results from lower energy experiments and to available theoretical models are presented.

   nucl-exhep-exJHEP(2016)·76 citations
3. 03*

   Insight from elliptic flow of open charm mesons using quark coalescence model at RHIC and LHC energies

   Roli Esha🇺🇸 · Md. Nasim🇺🇸 · Huan Zhong Huang🇺🇸

   A study of elliptic flow of open charm mesons, $D^0$ and $D_S^{\pm }$ using quark coalescence as a mechanism of hadronization of heavy quarks implemented in conjunction with A Multi Phase Transport (AMPT) model has been presented. We have studied the transverse momentum dependence of the elliptic flow parameter at mid-rapidity ($|y|$ $<$ 1.0) for Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV (RHIC) and Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV (LHC) for different values of partonic interaction cross-section and QCD coupling constant. We have compared our calculations with the experimentally measured data at the LHC energy. We have also studied the effect of shear viscosity on elliptic flow of open charm mesons within the transport model approach. Our study indicates that the elliptic flow of open charmed mesons is more sensitive to viscous properties of QGP medium as compared to light charged hadrons.

   ↳ nucl-thhep-phnucl-exJ.Phys.G(2017)·15 citations
4. 04*

   Baryons and the Borromeo

   Craig D. Roberts🇺🇸 · Jorge Segovia🇩🇪

   The kernels in the tangible matter of our everyday experience are composed of light quarks. At least, they are light classically; but they don't remain light. Dynamical effects within the Standard Model of Particle Physics change them in remarkable ways, so that in some configurations they appear nearly massless, but in others possess masses on the scale of light nuclei. Modern experiment and theory are exposing the mechanisms responsible for these remarkable transformations. The rewards are great if we can combine the emerging sketches into an accurate picture of confinement, which is such a singular feature of the Standard Model; and looming larger amongst the emerging ideas is a perspective that leads to a Borromean picture of the proton and its excited states.

   ↳ nucl-thhep-lathep-phnucl-exFew Body Syst.(2016)·21 citations
5. 05*

   Mean-field study of hot beta-stable protoneutron star matter: Impact of the symmetry energy and nucleon effective mass

   Ngo Hai Tan🇻🇳 · Doan Thi Loan🇻🇳 · Dao T. Khoa🇻🇳 · Jerome Margueron🇫🇷

   A consistent Hartree-Fock study of the equation of state (EOS) of asymmetric nuclear matter at finite temperature has been performed using realistic choices of the effective, density dependent nucleon-nucleon (NN) interaction, which were successfully used in different nuclear structure and reaction studies. Given the importance of the nuclear symmetry energy in the neutron star formation, EOS's associated with different behaviors of the symmetry energy were used to study hot asymmetric nuclear matter. The slope of the symmetry energy and nucleon effective mass with increasing baryon density was found to affect the thermal properties of nuclear matter significantly. Different density dependent NN interactions were further used to study the EOS of hot protoneutron star (PNS) matter of the $npe\mu \nu$ composition in $\beta$-equilibrium. The hydrostatic configurations of PNS in terms of the maximal gravitational mass $M_{\max }$ and radius, central density, pressure and temperature at the total entropy per baryon $S/A=1,2$ and 4 have been determined in both the neutrino-free and neutrino-trapped scenarios. The obtained results show consistently a strong impact of the symmetry energy and nucleon effective mass on thermal properties and composition of hot PNS matter. $M_{\max }$ values obtained for the (neutrino-free) $\beta$-stable PNS at $S/A=4$ were used to assess time $t_{\mathrm{BH}}$ of the collapse of 40 $M_{\odot }$ protoneutron progenitor to black hole, based on a correlation between $t_{\mathrm{BH}}$ and $M_{\max }$ found from the hydrodynamic simulation by Hempel {\it et al.}.

   ↳ nucl-thastro-ph.SRnucl-exPRC(2016)·24 citations
6. 06*

   Quantum canonical ensemble and correlation femtoscopy at fixed multiplicities

   S.V. Akkelin🇺🇦 · Yu.M. Sinyukov🇺🇦

   Identical particle correlations at fixed multiplicity are considered by means of quantum canonical ensemble of finite systems. We calculate one-particle momentum spectra and two-particle Bose-Einstein correlation functions in the ideal gas by using a recurrence relation for the partition function. Within such a model we investigate the validity of the thermal Wick's theorem and its applicability for decomposition of the two-particle distribution function. The dependence of the Bose-Einstein correlation parameters on the average momentum of the particle pair is also investigated. Specifically, we present the analytical formulas that allow one to estimate the effect of suppressing the correlation functions in a finite canonical system. The results can be used for the femtoscopy analysis of the A+A and p+p collisions with selected (fixed) multiplicity.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2016)·3 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.