Tue·Jun 23, 2015Tuesday·June 23, 2015

1. 01*

   The polarization observables T, P, and H and their impact on $\gamma p\to p{\pi }^0$ multipoles

   J. Hartmann🇩🇪 · H. Dutz🇩🇪 · A.V. Anisovich🇩🇪 · D. Bayadilov🇩🇪 · R. Beck🇩🇪 · M. Becker🇩🇪 · Y. Beloglazov🇷🇺 · A. Berlin🇩🇪 · M. Bichow🇩🇪 · S. Böse🇩🇪 · K.-Th. Brinkmann🇩🇪 · V. Crede🇺🇸 and 67 other authors

   Data on the polarization observables T, P, and H for the reaction $\gamma p\to p{\pi }^0$ are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results were extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. The data were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS detector. Within the Bonn-Gatchina partial wave analysis, the new polarization data lead to a significant narrowing of the error band for the multipoles for neutral-pion photoproduction.

   nucl-exPLB(2015)·40 citations
2. 02*

   Centrality dependence of high-$p_{\mathrm{T}}$ D meson suppression in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV

   ALICE Collaboration

   The nuclear modification factor, $R_{\mathrm{AA}}$, of the prompt charmed mesons ${\mathrm{D}}^0$, ${\mathrm{D}}^{+}$ and ${\mathrm{D}}^{\ast +}$, and their antiparticles, was measured with the ALICE detector in Pb-Pb collisions at a centre-of-mass energy $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV in two transverse momentum intervals, $5<p_{\mathrm{T}}<8$ GeV/$c$ and $8<p_{\mathrm{T}}<16$ GeV/$c$, and in six collision centrality classes. The $R_{\mathrm{AA}}$ shows a maximum suppression of a factor of 5-6 in the 10% most central collisions. The suppression and its centrality dependence are compatible within uncertainties with those of charged pions. A comparison with the $R_{\mathrm{AA}}$ of non-prompt $\mathrm{J}/\psi$ from B meson decays, measured by the CMS Collaboration, hints at a larger suppression of D mesons in the most central collisions.

   nucl-exhep-exJHEP(2015)·124 citations
3. 03*

   Low-energy Coulomb excitation of ${}^{62}$Fe and ${}^{62}$Mn following in-beam decay of ${}^{62}$Mn

   L. P. Gaffney · J. Van de Walle · B. Bastin · V. Bildstein · A. Blazhev · N. Bree · J. Cederkäll · I. Darby · H. De Witte · D. DiJulio · J. Diriken · V. N. Fedosseev and 17 other authors

   Sub-barrier Coulomb-excitation was performed on a mixed beam of ${}^{62}$Mn and ${}^{62}$Fe, following in-trap ${\beta }^{-}$ decay of ${}^{62}$Mn at REX-ISOLDE, CERN. The trapping and charge breeding times were varied in order to alter the composition of the beam, which was measured by means of an ionisation chamber at the zero-angle position of the Miniball array. A new transition was observed at 418~keV, which has been tentatively associated to a $(2^{+},3^{+})\to 1_{g.s.}^{+}$ transition. This fixes the relative positions of the $\beta$-decaying $4^{+}$ and $1^{+}$ states in ${}^{62}$Mn for the first time. Population of the $2_1^{+}$ state was observed in ${}^{62}$Fe and the cross-section determined by normalisation to the ${}^{109}$Ag target excitation, confirming the $B(E2)$ value measured in recoil-distance lifetime experiments.

   nucl-exEPJA(2015)·8 citations
4. 04*

   Probing flavor models with Ge-76-based experiments on neutrinoless double-beta decay

   Matteo Agostini🇩🇪 · Alexander Merle🇩🇪 · Kai Zuber🇩🇪

   The physics impact of a staged approach for double-beta decay experiments based on Ge-76 is studied. The scenario considered relies on realistic time schedules envisioned by the GERDA and the MAJORANA collaborations, which are jointly working towards the realization of a future larger scale Ge-76 experiment. Intermediate stages of the experiments are conceived to perform quasi background-free measurements, and different data sets can be reliably combined to maximize the physics outcome. The sensitivity for such a global analysis is presented, with focus on how neutrino flavor models can be probed already with preliminary phases of the experiments. The synergy between theory and experiment yields strong benefits for both sides: the model predictions can be used to sensibly plan the experimental stages, and results from intermediate stages can be used to constrain whole groups of theoretical scenarios. This strategy clearly generates added value to the experimental efforts, while at the same time it allows to achieve valuable physics results as early as possible.

   ↳ hep-exhep-phnucl-exphysics.ins-detEPJC(2016)·20 citations
5. 05*

   Jet measurements in polarized p+p collisions at STAR at RHIC

   Xuan Li🇺🇸

   Jet production in polarized $p+p$ collisions at $\sqrt{s}=200$ GeV and $\sqrt{s}=500$ GeV provides a powerful probe to study gluons inside the proton. The Solenoidal Tracker at RHIC (STAR) has the capability, with nearly full azimuthal ($2\pi$) coverage, to reconstruct jets at mid-rapidity ($|\eta |<1$). The latest STAR inclusive jet longitudinal double-spin asymmetry $A_{LL}$ measured in 200 GeV $p+p$ collisions provides better constraints on the polarized gluon distribution $\Delta g(x)$ for $0.05<x<0.2$ than previous measurements. A recent global QCD fit (DSSV 2014) which includes the 2009 RHIC results provides the first evidence of non-zero gluon contribution to the proton spin. A new inclusive jet cross section using the anti-$k_T$ algorithm provides potential insights into the unpolarized gluon distribution function, and the new inclusive jet $A_{LL}$ measurement in 510 GeV $p+p$ collisions shows consistent $x_T$ scaling with the 200 GeV result. Future measurements with continuing high energy polarized proton-proton running at $\sqrt{s}=500$ GeV at RHIC and detector upgrades in the forward direction will explore the gluonic contribution to the proton spin at low $x$ region.

   ↳ hep-exhep-phnucl-exPoS(2015)·7 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.