Thu·Mar 16, 2017Thursday·March 16, 2017

1. 01*

   Direct Evidence for Octupole Deformation in ${}^{146}$Ba and the Origin of Large $E1$ Moment Variations in Reflection-Asymmetric Nuclei

   Brian Bucher🇺🇸 · Shaofei Zhu · Ching-Yen Wu · Robert Janssens🇺🇸 · Remi Bernard🇫🇷 · Luis Robledo🇪🇸 · Tomas Rodriguez🇪🇸 · Doug Cline🇺🇸 · Adam Hayes🇺🇸 · Akaa Ayangeakaa🇺🇸 · Matt Buckner · Chris Campbell and 15 other authors

   Despite the more than one order of magnitude difference between the measured dipole moments in ${}^{144}$Ba and ${}^{146}$Ba, the strength of the octupole correlations in ${}^{146}$Ba are found to be as strong as those in ${}^{144}$Ba with a similarly large value of $B(E3;3^{-}\to 0^{+})$ determined as 48(${}_{-29}^{+21}$) W.u. The new results not only establish unambiguously the presence of a region of octupole deformation centered on these neutron-rich Ba isotopes, but also manifest the dependence of the electric dipole moments on the occupancy of different neutron orbitals in nuclei with enhanced octupole strength, as revealed by fully microscopic calculations.

   nucl-exPRL(2017)·116 citations
2. 02*

   Approximate transmission coefficients in heavy ion fusion

   A. J. Toubiana🇧🇷 · L. F. Canto🇧🇷 · M. S. Hussein🇧🇷

   In this paper we revisit the one-dimensional tunnelling problem. We consider different approximations for the transmission through the Coulomb barrier in heavy ion collisions at near-barrier energies. First, we discuss approximations of the barrier shape by functional forms where the transmission coefficient is known analytically. Then, we consider Kemble's approximation for the transmission coefficient. We show how this approximation can be extended to above-barrier energies by performing the analytical continuation of the radial coordinate to the complex plane. We investigate the validity of the different approximations considered in this paper by comparing their predictions for transmission coefficients and cross sections of three heavy ion systems with the corresponding quantum mechanical results.

   ↳ nucl-thnucl-exBraz.J.Phys.(2017)·16 citations
3. 03*

   Light vector correlator in medium: Wilson coefficients up to dimension 6 operators

   HyungJoo Kim🇰🇷 · Philipp Gubler🇰🇷 · Su Houng Lee🇰🇷

   As an improvement of the QCD sum rule method to study modifications of light vector mesons in nuclear matter and/or at finite temperature, we calculate the Wilson coefficients of all independent gluonic non-scalar operators up to dimension 6 in the operator product expansion (OPE) of the vector channel for light quarks. To obtain the gluon part of the light quark OPE from the heavy quark one, we also compute the heavy quark expansion of the relevant quark condensates. Together with the results for the quark operators that are already available in the literature, this completes the OPE of the vector channel in a hot or dense medium for operators up to dimension 6.

   ↳ hep-phhep-exhep-latnucl-ex+1PLB(2017)·17 citations
4. 04*

   Exposing strangeness: projections for kaon electromagnetic form factors

   Fei Gao🇨🇳 · Lei Chang🇨🇳 · Yu-Xin Liu🇨🇳 · Craig D. Roberts🇺🇸 · Peter C. Tandy🇺🇸

   A continuum approach to the kaon and pion bound-state problems is used to reveal their electromagnetic structure. For both systems, when used with parton distribution amplitudes appropriate to the scale of the experiment, Standard Model hard-scattering formulae are accurate to within 25% at momentum transfers $Q^2\approx 8$GeV${}^2$. There are measurable differences between the distribution of strange and normal matter within the kaons, e.g. the ratio of their separate contributions reaches a peak value of $1.5$ at $Q^2\approx 6$GeV${}^2$. Its subsequent $Q^2$-evolution is accurately described by the hard scattering formulae. Projections for kaon and pion form factors at timelike momenta beyond the resonance region are also presented. These results and projections should prove useful in planning next-generation experiments.

   ↳ nucl-thhep-exhep-lathep-ph+1PRD(2017)·69 citations
5. 05*

   Kinetic freeze-out temperatures in central and peripheral collisions: Which one is larger?

   Hai-Ling Lao🇨🇳 · Fu-Hu Liu🇨🇳 · Bao-Chun Li🇨🇳 · Mai-Ying Duan🇨🇳

   The kinetic freeze-out temperatures, $T_0$, in nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies are extracted by four methods: i) the Blast-Wave model with Boltzmann-Gibbs statistics (the BGBW model), ii) the Blast-Wave model with Tsallis statistics (the TBW model), iii) the Tsallis distribution with flow effect (the improved Tsallis distribution), and iv) the intercept in $T=T_0+a{m}_0$ (the alternative method), where $m_0$ denotes the rest mass and $T$ denotes the effective temperature which can be obtained by different distribution functions. It is found that the relative sizes of $T_0$ in central and peripheral collisions obtained by the conventional BGBW model which uses a zero or nearly zero transverse flow velocity, ${\beta }_T$, are contradictory in tendency with other methods. With a re-examination for ${\beta }_T$ in the first method in which ${\beta }_T$ is taken to be $\sim (0.40\pm 0.07)c$, a recalculation presents a consistent result with others. Finally, our results show that the kinetic freeze-out temperature in central collisions is larger than that in peripheral collisions.

   ↳ nucl-thhep-exhep-phnucl-exNucl.Sci.Tech.(2018)·56 citations
6. 06*

   Light fragment production at CERN Super Proton Synchrotron

   Yu. B. Ivanov🇷🇺 · A. A. Soldatov🇷🇺

   Recent data on the deutron and ${}^3$He production in central Pb+Pb collisions at the CERN Super Proton Synchrotron (SPS) energies measured by the NA49 collaboration are analyzed within the model of the three-fluid dynamics (3FD) complemented by the coalescence model for the light-fragment production. The simulations are performed with different equations of state---with and without deconfinement transition. It is found that scenarios with the deconfinement transition are preferable for reproduction rapidity distributions of deuterons and ${}^3$He, the corresponding results well agree with the experimental data. At the same time the calculated transverse-mass spectra of ${}^3$He at midrapidity do not that nice agree with the experimental data. The latter apparently indicates that coalescence coefficients should be temperature and/or momentum dependent.

   ↳ nucl-thhep-phnucl-exEPJA(2017)·10 citations
7. 07*

   A pulsed, mono-energetic and angular-selective UV photo-electron source for the commissioning of the KATRIN experiment

   J. Behrens🇩🇪 · P. C.-O. Ranitzsch🇩🇪 · M. Beck🇩🇪 · A. Beglarian🇩🇪 · M. Erhard🇩🇪 · S. Groh🇩🇪 · V. Hannen🇩🇪 · M. Kraus🇩🇪 · H.-W. Ortjohann🇩🇪 · O. Rest🇩🇪 · K. Schlösser🇩🇪 · T. Thümmler🇩🇪 and 6 other authors

   The KATRIN experiment aims to determine the neutrino mass scale with a sensitivity of 200 meV/c^2 (90% C.L.) by a precision measurement of the shape of the tritium $\beta$-spectrum in the endpoint region. The energy analysis of the decay electrons is achieved by a MAC-E filter spectrometer. To determine the transmission properties of the KATRIN main spectrometer, a mono-energetic and angular-selective electron source has been developed. In preparation for the second commissioning phase of the main spectrometer, a measurement phase was carried out at the KATRIN monitor spectrometer where the device was operated in a MAC-E filter setup for testing. The results of these measurements are compared with simulations using the particle-tracking software "Kassiopeia", which was developed in the KATRIN collaboration over recent years.

   ↳ physics.ins-detnucl-exEPJC(2017)·37 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.