Tue·Feb 17, 2015Tuesday·February 17, 2015

1. 01*

   Low-energy electric dipole response in 120Sn

   A.M. Krumbholz🇩🇪 · P. von Neumann-Cosel🇩🇪 · T. Hashimoto🇯🇵 · A. Tamii🇯🇵 · T. Adachi🇯🇵 · C.A. Bertulani🇺🇸 · H. Fujita🇯🇵 · Y. Fujita🇯🇵 · E. Ganioglu🇹🇷 · K. Hatanaka🇯🇵 · C. Iwamoto🇯🇵 · T. Kawabata🇯🇵 and 20 other authors

   The electric dipole strength in 120Sn has been extracted from proton inelastic scattering experiments at E_p = 295 MeV and at forward angles including 0 degree. Below neutron threshoild it differs from the results of a 120Sn(gamma,gamma') experiment and peaks at an excitation energy of 8.3 MeV. The total strength corresponds to 2.3(2)% of the energy-weighted sum rule and is more than three times larger than what is observed with the (gamma,gamma') reaction. This implies a strong fragmentation of the E1 strength and/or small ground state branching ratios of the excited 1- states.

   nucl-exnucl-thPLB(2015)·72 citations
2. 02*

   Detailed study of parton energy loss via measurement of fractional momentum loss of high $p_T$ hadrons in heavy ion collisions

   Takao Sakaguchi (for the PHENIX collaboration)🇺🇸

   PHENIX measurement of the fractional momentum loss ($d{p}_T/p_T$) of high $p_T$ identified hadrons are presented. The $d{p}_T/p_T$ of high $p_T$ pizero which are computed from 39GeV Au+Au over to 2.76TeV Pb+Pb are found to vary by a factor of six. We plotted the $d{p}_T/p_T$ against several global variables, $N_{part}$, $N_{qp}$ and $dN/deta$, and found global features. It was found that 200GeV Au+Au points are merging into the central 2.76TeV Pb+Pb points when plotting $d{p}_T/p_T$ against $dN/deta$.

   nucl-exnucl-thJ.Phys.Conf.Ser.(2017)·0 citations
3. 03*

   Improvement of the Energy Resolution via an Optimized Digital Signal Processing in GERDA Phase I

   M. Agostini🇩🇪 · M. Allardt🇩🇪 · A.M. Bakalyarov🇷🇺 · M. Balata🇮🇹 · I. Barabanov🇷🇺 · N. Barros🇵🇹 · L. Baudis🇨🇭 · C. Bauer🇩🇪 · N. Becerici-Schmidt🇩🇪 · E. Bellotti🇮🇹 · S. Belogurov🇷🇺 · S.T. Belyaev🇷🇺 and 102 other authors

   An optimized digital shaping filter has been developed for the GERDA experiment which searches for neutrinoless double beta decay in 76Ge. The GERDA Phase I energy calibration data have been reprocessed and an average improvement of 0.3 keV in energy resolution (FWHM) at the 76Ge Q value for 0\nu\beta\beta decay is obtained. This is possible thanks to the enhanced low-frequency noise rejection of this Zero Area Cusp (ZAC) signal shaping fillter.

   ↳ physics.ins-detnucl-exEPJC(2015)·55 citations
4. 04*

   Effective theory for the non-rigid rotor in an electromagnetic field: Toward accurate and precise calculations of E2 transitions in deformed nuclei

   E. A. Coello Pérez · T. Papenbrock🇺🇸

   We present a model-independent approach to electric quadrupole transitions of deformed nuclei. Based on an effective theory for axially symmetric systems, the leading interactions with electromagnetic fields enter as minimal couplings to gauge potentials, while subleading corrections employ gauge-invariant non-minimal couplings. This approach yields transition operators that are consistent with the Hamiltonian, and the power counting of the effective theory provides us with theoretical uncertainty estimates. We successfully test the effective theory in homonuclear molecules that exhibit a large separation of scales. For ground-state band transitions of rotational nuclei, the effective theory describes data well within theoretical uncertainties at leading order. In order to probe the theory at subleading order, data with higher precision would be valuable. For transitional nuclei, next-to-leading order calculations and the high-precision data are consistent within the theoretical uncertainty estimates. We also study the faint inter-band transitions within the effective theory and focus on the $E2$ transitions from the $0_2^{+}$ band (the "$\beta$ band") to the ground-state band. Here, the predictions from the effective theory are consistent with data for several nuclei, thereby proposing a solution to a long-standing challenge.

   ↳ nucl-thnucl-exPRC(2015)·24 citations
5. 05*

   Shape and flow fluctuations in ultra-central Pb+Pb collisions at the LHC

   Chun Shen🇨🇦 · Zhi Qiu🇺🇸 · Ulrich Heinz🇺🇸

   In ultra-central heavy-ion collisions, anisotropic hydrodynamic flow is generated by density fluctuations in the initial state rather than by geometric overlap effects. For a given centrality class, the initial fluctuation spectrum is sensitive to the method chosen for binning the events into centrality classes. We show that sorting events by total initial entropy or by total final multiplicity yields event classes with equivalent statistical fluctuation properties, in spite of viscous entropy production during the fireball evolution. With this initial entropy-based centrality definition we generate several classes of ultra-central Pb+Pb collisions at LHC energies and evolve the events using viscous hydrodynamics with non-zero shear but vanishing bulk viscosity. Comparing the predicted anisotropic flow coefficients for charged hadrons with CMS data we find that both the Monte Carlo Glauber (MC-Glb) and Monte Carlo Kharzeev-Levin-Nardi (MC-KLN) models produce initial fluctuation spectra that are incompatible with the measured final anisotropic flow power spectrum, for any choice of the specific shear viscosity. In spite of this failure, we show that the hydrodynamic model can qualitatively explain, in terms of event-by-event fluctuations of the anisotropic flow coefficients and flow angles, the breaking of flow factorization for elliptic, triangular and quadrangular flow measured by the CMS experiment. For elliptic flow, this factorization breaking is large in ultra-central collisions. We conclude that the bulk of the experimentally observed flow factorization breaking effects are qualitatively explained by hydrodynamic evolution of initial-state fluctuations, but that their quantitative description requires a better understanding of the initial fluctuation spectrum.

   ↳ nucl-thnucl-exPRC(2015)·58 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.