Tue·Jul 19, 2011Tuesday·July 19, 2011

1. 01*

   An Improved Limit on Pauli-Exclusion-Principle Forbidden Atomic Transitions

   S. R. Elliott🇺🇸 · B. H. LaRoque🇺🇸 · V. M. Gehman🇺🇸 · M. F. Kidd🇺🇸 · M. Chen🇺🇸

   We have examined the atomic theory behind recent constraints on the violation of the Pauli Exclusion Principle derived from experiments that look for x rays emitted from conductors while a large current is present. We also re-examine the assumptions underlying such experiments. We use the results of these studies to assess pilot measurements to develop an improved test of the Principle. We present an improved limit of $(1/2){\beta }^2<2.6\times 10^{-39}$ on the Pauli Exclusion Principle. This limit is the best to date for interactions between a system of fermions and a fermion that has not previously interacted with that given system. That is, for systems that do not obviously violate the Messiah-Greenberg symmetrization-postulate selection rule.

   nucl-exFound.Phys.(2012)·35 citations
2. 02*

   Studies of Jet Quenching in HI Collisions at CMS

   Frank Ma (for the CMS collaboration)🇺🇸

   Jet production in PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV was studied using the CMS detector at the LHC, using a data sample corresponding to an integrated luminosity of 6.7 inverse microbarn. Dijets were reconstructed using the CMS calorimeters, and a significant energy imbalance was observed between the leading jet and the away-side jet with increasing centrality. Correlation studies of jets and tracks reveal that the energy of the away-side jet is redistributed to lower pt and wider angle outside of the jet cone.

   nucl-ex1 citation
3. 03*

   Experimental Status of Vud from Neutron Decay

   Bastian Märkisch🇫🇷

   The matrix element Vud of the CKM matrix can be determined by two independent measurements on neutron decay: the neutron lifetime tau and the ratio of coupling constants lambda, which is most precisely determined by measurements of the beta asymmetry angular correlation coefficient A. We present recent progress on the determination of these values and derive a world average of Vud = 0.9743 (2)RC (8)tau (12)lambda.

   nucl-ex6 citations
4. 04*

   Investigation of $K^0{\Sigma }^{+}$ photoproduction with the CBELSA/TAPS experiment

   T.C. Jude (for the CBELSA/TAPS and BGO-OD collaborations)🇩🇪

   $\gamma (p,K^0){\Sigma }^{+}$ cross section was measured at the CBELSA/TAPS experiment at the ELSA electron stretcher facility. A cusp-like structure was apparent near the $K^{\ast }$ production threshold, where the cross section reduced by a factor of four in the forward direction. It is speculated that t-channel $K^{\ast }$ exchange, and meson-hyperon dynamically generated states may have large contributions to the cross section. The motivation for the extraction of the beam-target double polarisation observable, $E$, is discussed, and the new experiment, BGO-OD at the ELSA facility is introduced.

   nucl-exAIP Conf.Proc.(2012)·2 citations
5. 05*

   Magnetic effects in heavy-ion collisions at intermediate energies

   Li Ou🇺🇸 · Bao-An Li🇺🇸

   The time-evolution and space-distribution of internal electromagnetic fields in heavy-ion reactions at beam energies between 200 and 2000 MeV/nucleon are studied within an Isospin-dependent Boltzmann-Uhling-Uhlenbeck transport model IBUU11. While the magnetic field can reach about $7\times 10^{16}$ G which is significantly higher than the estimated surface magnetic field ($\sim 10^{15}$ G) of magnetars, it has almost no effect on nucleon observables as the Lorentz force is normally much weaker than the nuclear force. Very interestingly, however, the magnetic field generated by the projectile-like (target-like) spectator has a strong focusing/diverging effect on positive/negative pions at forward (backward) rapidities. Consequently, the differential ${\pi }^{-}/{\pi }^{+}$ ratio as a function of rapidity is significantly altered by the magnetic field while the total multiplicities of both positive and negative pions remain about the same. At beam energies above about 1 GeV/nucleon, while the integrated ratio of total ${\pi }^{-}$ to ${\pi }^{+}$ multiplicities is not, the differential ${\pi }^{-}/{\pi }^{+}$ ratio is sensitive to the density dependence of nuclear symmetry energy $E_{\mathrm{sym}}(\rho )$. Our findings suggest that magnetic effects should be carefully considered in future studies of using the differential ${\pi }^{-}/{\pi }^{+}$ ratio as a probe of the $E_{\mathrm{sym}}(\rho )$ at supra-saturation densities.

   ↳ nucl-thnucl-exPRC(2011)·74 citations
6. 06*

   Reference heavy flavour cross sections in pp collisions at sqrt(s) = 2.76 TeV, using a pQCD-driven sqrt(s)-scaling of ALICE measurements at sqrt(s) = 7 TeV

   R. Averbeck🇩🇪 · N. Bastid🇫🇷 · Z. Conesa del Valle🇨🇭 · P. Crochet🇫🇷 · A. Dainese🇮🇹 · X. Zhang🇫🇷

   We provide a reference in proton-proton collisions at the energy of the Pb-Pb 2010 run at the LHC, sqrt(s) = 2.76 TeV, for the pt-differential production cross section of D0, D+, and D*+ mesons in |y| < 0.5, of electrons from heavy flavour decays in |y| < 0.9, and of muons from heavy flavour decays in 2.5 < y < 4. The reference is obtained by applying a pQCD-driven scaling (based on the FONLL calculation) to ALICE preliminary data at sqrt(s) = 7 TeV. In order to validate the procedure, we scale the D meson cross section to sqrt(s) = 1.96 TeV and compare to the corresponding measurements from the CDF experiment.

   ↳ hep-phhep-exnucl-ex111 citations
7. 07*

   Fluctuation Probes of Early-Time Correlations in Nuclear Collisions

   Sean Gavin🇺🇸 · George Moschelli🇩🇪

   Correlation measurements imply that anisotropic flow in nuclear collisions includes a novel triangular component along with the more familiar elliptic-flow contribution. Triangular flow has been attributed to event-wise fluctuations in the initial shape of the collision volume. We ask two questions: 1) How do these shape fluctuations impact other event-by-event observables? 2) Can we disentangle fundamental information on the early time fluctuations from the complex flow that results? We study correlation and fluctuation observables in a framework in which flux tubes in an early Glasma stage later produce hydrodynamic flow. Calculated multiplicity and transverse momentum fluctuations are in excellent agreement with data from 62.4 GeV Au+Au up to 2.76 TeV Pb+Pb.

   ↳ nucl-thhep-phnucl-exPRC(2012)·49 citations
8. 08*

   Recent Measurements of Neutrino-Nucleus Quasi-Elastic Scattering

   M.O. Wascko🇬🇧

   We present recent measurements of neutrino charged current quasi-elastic (CC QE) scattering, nu_mu + p -> mu- + n. Measurements of CC QE on carbon near 1 GeV by MiniBooNE and SciBooNE, as well as measurements on iron at 3 GeV by MINOS, disagree with current interaction models, while measurements at higher energies on carbon by NOMAD show excellent agreement with those same models.

   ↳ hep-exhep-phnucl-exNucl.Phys.Proc.Supl.(2012)·1 citation
9. 09*

   The low energy frontier: What is exciting about physics below the top RHIC energy

   Marcus Bleicher🇩🇪

   These proceedings summarize my plenary talk at Quark Matter 2011 with a focus on the future perspectives of the low energy programs at RHIC, FAIR, NICA and CERN.

   ↳ nucl-thhep-phnucl-exJ.Phys.G(2011)·9 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.