Tue·Dec 5, 2017Tuesday·December 5, 2017

1. 01*

   New result for the neutron $\beta$-asymmetry parameter $A_0$ from UCNA

   M. A.-P. Brown · E.B. Dees · E. Adamek · B. Allgeier · M. Blatnik · T.J. Bowles · L.J. Broussard · R. Carr · S. Clayton · C. Cude-Woods · S. Currie · X. Ding and 48 other authors

   The neutron $\beta$-decay asymmetry parameter $A_0$ defines the correlation between the spin of the neutron and the momentum of the emitted electron, which determines $\lambda =\frac{g_A}{g_V}$, the ratio of the axial-vector to vector weak coupling constants. The UCNA Experiment, located at the Ultracold Neutron facility at the Los Alamos Neutron Science Center, is the first to measure such a correlation coefficient using ultracold neutrons (UCN). Following improvements to the systematic uncertainties and increased statistics, we report the new result $A_0=-0.12054(44{)}_{\mathrm{stat}}(68{)}_{\mathrm{syst}}$ which yields $\lambda \equiv \frac{g_A}{g_V}=-1.2783(22)$. Combination with the previous UCNA result and accounting for correlated systematic uncertainties produces $A_0=-0.12015(34{)}_{\mathrm{stat}}(63{)}_{\mathrm{syst}}$ and $\lambda \equiv \frac{g_A}{g_V}=-1.2772(20)$.

   nucl-exPRC(2018)·138 citations
2. 02*

   A unified model for nucleosynthesis of heavy elements in stars

   Miklós Kiss · Zoltán Trócsányi🇭🇺

   We propose a unified model for the nucleosynthesis of heavy (A > 57) elements in stars. The neutron flux can be set to describe neutron capture in arbitrary neutron flux. Our approach solves the coupled differential equations, that describe the neutron capture and decays of 2696 nuclei, numerically without truncating those to include only either capture or decay as traditionally assumed in weak neutron flux (s process). As a result the synthesis of heavy nuclei always evolves along a wide band in the valley of stable nuclei. The observed abundances in the Solar system are reproduced reasonably already in the simplest version of the model. The model predicts that the nucleosynthesis in weak or modest neutron flux produces elements that are traditionally assumed to result in the high neutron flux of supernovae explosions (r process).

   ↳ astro-ph.SRnucl-ex2010 J. Phys.: Conf. Ser. 202 012024·0 citations
3. 03*

   Temperature dependence of transport coefficients of QCD in high-energy heavy-ion collisions

   Kazuhisa Okamoto🇯🇵 · Chiho Nonaka🇯🇵

   Using our developed new relativistic viscous hydrodynamics code, we investigate the temperature dependence of shear and bulk viscosities from comparison with the ALICE data: single particle spectra and collective flows of Pb+Pb $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV collisions at the Large Hadron Collider. We find that from the comprehensive analyses of centrality dependence of single particle spectra and collective flows we can extract detailed information on the quark-gluon plasma bulk property, without the information being smeared by the final state interactions.

   ↳ nucl-thhep-phnucl-exPRC(2018)·16 citations
4. 04*

   Sequential fission of highly excited compound nuclei in a 4D Langevin approach

   D. Gruyer🇫🇷 · K. Mazurek🇵🇱 · J. D. Frankland🇫🇷 · E. Bonnet🇫🇷 · P. N. Nadtochy🇷🇺 · A. Chbihi🇫🇷 · J.P. Wieleczko🇫🇷

   In highly dissipative collisions between heavy ions, the optimal conditions to investigate different de-excitation channels of hot nuclei such as evaporation, fission or multifragmentation are well known. One crucial issue remains the excitation energy region where fission gives way to multifragmentation. In this paper, the onset of multi-fragment exit channels is investigated in terms of sequential fission. For the first time, the dynamical approach based on solving Langevin transport equations in multidimensional collective coordinate space is used to follow the de-excitation of highly excited (up to E* =223-656 MeV) 248Rf compound nuclei. The sequential fission model we propose contains two steps: (1) time evolution of the compound nucleus up to either scission or residue formation, followed by (2) dynamical calculations of each primary fragment separately. This procedure allows to obtain from one to four cold fragments correlated with the light particles emitted during the de-excitation process. Experimental data measured with the INDRA detector for the 129Xe+ natSn reaction at beam energies 8, 12 and 15 MeV/nucleon provide strong constraints for this sequential fission scenario.

   ↳ nucl-thnucl-ex0 citations
5. 05*

   Large directed flow of open charm mesons probes the three dimensional distribution of matter in heavy ion collisions

   Sandeep Chatterjee🇵🇱 · Piotr Bożek🇵🇱

   Thermalized matter created in non-central relativistic heavy-ion collisions is expected to be tilted in the reaction plane with respect to the beam axis. The most notable consequence of this forward-backward symmetry breaking is the observation of rapidity-odd directed flow for charged particles. On the other hand, the production points for heavy quarks are forward-backward symmetric and shifted in the transverse plane with respect to the fireball. The drag of heavy quarks from the asymmetrically distributed thermalized matter generates a large directed flow for heavy flavor mesons. We predict a very large rapidity odd directed flow of $D$ mesons in non-central Au-Au collisions at $\sqrt{s_{NN}}=200$ GeV, $several$ $times$ $larger$ than for charged particles. A possible experimental observation of a large directed flow for heavy flavor mesons would represent an almost direct probe of the 3-dimensional distribution of matter in heavy-ion collisions.

   ↳ nucl-thhep-exhep-phnucl-exPRL(2018)·87 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.