Mon·Jun 15, 2015Monday·June 15, 2015

1. 01*

   Systematic trends in beta-delayed particle emitting nuclei: The case of beta-p-alpha emission from 21Mg

   M.V. Lund🇩🇰 · M.J.G. Borge🇨🇭 · J.A. Briz🇪🇸 · J. Cederkäll🇸🇪 · H.O.U. Fynbo🇩🇰 · J. H. Jensen🇩🇰 · B. Jonson🇸🇪 · K. L. Laursen🇩🇰 · T. Nilsson🇸🇪 · A. Perea🇪🇸 · V. Pesudo🇪🇸 · K. Riisager🇩🇰 · O. Tengblad🇪🇸

   We have observed beta+-delayed alpha and p-alpha emission from the proton-rich nucleus 21Mg produced at the ISOLDE facility at CERN. The assignments were cross-checked with a time distribution analysis. This is the third identified case of beta-p-alpha emission. We discuss the systematic of beta-delayed particle emission decays, show that our observed decays fit naturally into the existing pattern, and argue that the patterns are to a large extent caused by odd-even effects.

   nucl-exPLB(2015)·12 citations
2. 02*

   Heavy-flavour and quarkonium production in the LHC era: from proton-proton to heavy-ion collisions

   A. Andronic🇩🇪 · F. Arleo🇫🇷 · R. Arnaldi🇮🇹 · A. Beraudo🇮🇹 · E. Bruna🇮🇹 · D. Caffarri🇨🇭 · Z. Conesa del Valle🇫🇷 · J.G. Contreras🇨🇿 · T. Dahms🇺🇸 · A. Dainese🇮🇹 · M. Djordjevic🇷🇸 · E.G. Ferreiro🇪🇸 and 44 other authors

   This report reviews the study of open heavy-flavour and quarkonium production in high-energy hadronic collisions, as tools to investigate fundamental aspects of Quantum Chromodynamics, from the proton and nucleus structure at high energy to deconfinement and the properties of the Quark-Gluon Plasma. Emphasis is given to the lessons learnt from LHC Run 1 results, which are reviewed in a global picture with the results from SPS and RHIC at lower energies, as well as to the questions to be addressed in the future. The report covers heavy flavour and quarkonium production in proton-proton, proton-nucleus and nucleus-nucleus collisions. This includes discussion of the effects of hot and cold strongly interacting matter, quarkonium photo-production in nucleus-nucleus collisions and perspectives on the study of heavy flavour and quarkonium with upgrades of existing experiments and new experiments. The report results from the activity of the SaporeGravis network of the I3 Hadron Physics programme of the European Union 7th Framework Programme.

   nucl-exhep-exhep-phnucl-thEPJC(2016)·815 citations
3. 03*

   Measurement of jet quenching with semi-inclusive hadron-jet distributions in central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV

   ALICE Collaboration

   We report the measurement of a new observable of jet quenching in central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV, based on the semi-inclusive rate of charged jets recoiling from a high transverse momentum (high-$p_{\mathrm{T}}$) charged hadron trigger. Jets are measured using collinear-safe jet reconstruction with infrared cutoff for jet constituents of 0.15 GeV/$c$, for jet resolution parameters $R=0.2$, 0.4 and 0.5. Underlying event background is corrected at the event-ensemble level, without imposing bias on the jet population. Recoil jet spectra are reported in the range $20<p_{\mathrm{T},\mathrm{jet}}^{\mathrm{ch}}<100$ GeV/$c$. Reference distributions for pp collisions at $\sqrt{s}=2.76$ TeV are calculated using Monte Carlo and NLO pQCD methods, which are validated by comparing with measurements in pp collisions at $\sqrt{s}=7$ TeV. The recoil jet yield in central Pb-Pb collisions is found to be suppressed relative to that in pp collisions. No significant medium-induced broadening of the intra-jet energy profile is observed within 0.5 radians relative to the recoil jet axis. The angular distribution of the recoil jet yield relative to the trigger axis is found to be similar in central Pb-Pb and pp collisions, with no significant medium-induced acoplanarity observed. Large-angle jet deflection, which may provide a direct probe of the nature of the quasi-particles in hot QCD matter, is explored.

   nucl-exJHEP(2015)·196 citations
4. 04*

   Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton

   C. Fanelli🇮🇹 · E. Cisbani🇮🇹 · D. J. Hamilton🇬🇧 · G. Salme🇮🇹 · B. Wojtsekhowski🇺🇸 · A. Ahmidouch🇺🇸 · J. R. M. Annand🇬🇧 · H. Baghdasaryan🇺🇸 · J. Beaufait🇺🇸 · P. Bosted🇺🇸 · E. J. Brash🇺🇸 · C. Butuceanu🇨🇦 and 56 other authors

   Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7~GeV at a proton scattering angle of \cma$=70^{\circ }$. The longitudinal transfer \KLL, measured to be $0.645\pm 0.059\pm 0.048$, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is $\sim$3~times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.

   nucl-exPRL(2015)·17 citations
5. 05*

   Degeneracies of particle and nuclear physics uncertainties in neutrinoless double beta decay

   E. Lisi (INFN, Bari)🇮🇹 · A. Rotunno (U. of Bari)🇮🇹 · F. Simkovic (Comenius U. & JINR & CTU Prague)🇸🇰

   Theoretical estimates for the half life of neutrinoless double beta decay in candidate nuclei are affected by both particle and nuclear physics uncertainties, which may complicate the interpretation of decay signals or limits. We study such uncertainties and their degeneracies in the following context: three nuclei of great interest for large-scale experiments (76-Ge, 130-Te, 136-Xe), two representative particle physics mechanisms (light and heavy Majorana neutrino exchange), and a large set of nuclear matrix elements (NME), computed within the quasiparticle random phase approximation (QRPA). It turns out that the main theoretical uncertainties, associated with the effective axial coupling g_A and with the nucleon-nucleon potential, can be parametrized in terms of NME rescaling factors, up to small residuals. From this parametrization, the following QRPA features emerge: (1) the NME dependence on g_A is milder than quadratic; (2) in each of the two mechanisms, the relevant lepton number violating parameter is largely degenerate with the NME rescaling factors; and (3) the light and heavy neutrino exchange mechanisms are basically degenerate in the above three nuclei. We comment on the challenging theoretical and experimental improvements required to reduce such particle and nuclear physics uncertainties and their degeneracies.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2015)·29 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.