Thu·Jul 3, 2014Thursday·July 3, 2014

1. 01*

   Gluonic Excitations and Experimental Hall-D at Jefferson Lab

   Justin R. Stevens🇺🇸

   A new tagged photon beam facility is being constructed in experimental Hall-D at Jefferson Lab as a part of the 12 GeV upgrade program. The 9 GeV linearly-polarized photon beam will be produced via coherent Bremsstrahlung using the CEBAF electron beam, incident on a diamond radiator. The GlueX experiment in Hall-D will use this photon beam to search for and study the pattern of gluonic excitations in the meson spectrum produced through photoproduction reactions with a liquid hydrogen target. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons, that are formed by exciting the gluonic field that couples the quarks. A subset of these hybrid mesons are predicted to have exotic quantum numbers which cannot be formed from a simple $q\bar{q}$ pair, and thus provide an ideal laboratory for testing QCD in the confinement regime. In these proceedings the status of the construction and installation of the GlueX detector will be presented, in addition to simulation results for some reactions of interest in hybrid meson searches.

   nucl-exPoS(2014)·0 citations
2. 02*

   Probing Sea Quark and Gluon Polarization at STAR

   Justin R. Stevens (part of the STAR Collaboration)🇺🇸

   One of the primary goals of the spin program at the Relativistic Heavy Ion Collider (RHIC) is to determine the polarization of the sea quarks and gluons in the proton. The polarization of the sea quarks is probed through the production of $W^{-(+)}$ bosons via the annihilation of $\bar{u}+d(\bar{d}+u)$, at leading order. In this proceedings we report measurements of the single-spin asymmetry, $A_L$, for $W$ boson production at $\sqrt{s}=510$ GeV, and the new constraints these results place on the antiquark helicity distributions. Recent results on the longitudinal double-spin asymmetry, $A_{LL}$, for inclusive and di-jet production at $\sqrt{s}=200$ GeV are also presented. The inclusive jet results provide the first experimental indication of non-zero gluon polarization in the $x$ range probed at RHIC.

   nucl-exhep-exPoS(2014)·0 citations
3. 03*

   Laser spectroscopy of francium isotopes at the borders of the region of reflection asymmetry

   I. Budinčević🇧🇪 · J. Billowes🇬🇧 · M. L. Bissell🇧🇪 · T. E. Cocolios🇬🇧 · R. P. de Groote🇧🇪 · S. De Schepper🇧🇪 · V. N. Fedosseev🇨🇭 · K. T. Flanagan🇬🇧 · S. Franchoo🇫🇷 · R. F. Garcia Ruiz🇧🇪 · H. Heylen🇧🇪 · K. M. Lynch🇧🇪 and 8 other authors

   The magnetic dipole moments and changes in mean-square charge radii of the neutron-rich ${}^{218m,219,229,231}\text{Fr}$ isotopes were measured with the newly-installed Collinear Resonance Ionization Spectroscopy (CRIS) beam line at ISOLDE, CERN, probing the $7s{}^2{S}_{1/2}$ to $8p{}^2{P}_{3/2}$ atomic transition. The $\delta ⟨r^2{⟩}^{A,221}$ values for ${}^{218m,219}\text{Fr}$ and ${}^{229,231}\text{Fr}$ follow the observed increasing slope of the charge radii beyond $N=126$. The charge radii odd-even staggering in this neutron-rich region is discussed, showing that ${}^{220}\text{Fr}$ has a weakly inverted odd-even staggering while ${}^{228}\text{Fr}$ has normal staggering. This suggests that both isotopes reside at the borders of a region of inverted staggering, which has been associated with reflection-asymmetric shapes. The $g{(}^{219}\text{Fr})=+0.69(1)$ value supports a $\pi 1h_{9/2}$ shell model configuration for the ground state. The $g{(}^{229,231}\text{Fr})$ values support the tentative $I^{\pi }{(}^{229,231}\text{Fr})=(1/2^{+})$ spin, and point to a $\pi s_{1/2}^{-1}$ intruder ground state configuration.

   nucl-exPRC(2014)·38 citations
4. 04*

   Study of the PYTHIA $\Delta \eta \Delta \varphi$ correlation as a function of multiplicity and transverse sphericity in proton-proton collisions at 7 TeV

   Edgar Perez🇲🇽 · Guy Paic🇲🇽 · Antonio Ortiz🇲🇽 · Eleazar Cuautle🇲🇽

   The study and understanding of the details of proton-proton collisions is important since they are the benchmark for the comparison with heavy ion results. In the present work we have studied the $\Delta \eta \Delta \varphi$ correlations as a function of the event multiplicity and transverse sphericity in pp collisions at $\sqrt{s}$ = 7 TeV using PYTHIA 8.180. The results show large variation in the shape of the correlation as a function of the sphericity and multiplicity indicating the importance of slicing the data in bins of both observables to better understand the complexity of the interactions. Motivated by the radial flow patterns originated by color reconnection (CR), results with and without CR together with dihadron correlations are discussed.

   ↳ hep-phnucl-exJ.Phys.Conf.Ser.(2015)·3 citations
5. 05*

   A compact ultra-clean system for deploying radioactive sources inside the KamLAND detector

   T.I. Banks🇺🇸 · S.J. Freedman🇺🇸 · J. Wallig🇺🇸 · N. Ybarrolaza🇺🇸 · A. Gando🇯🇵 · Y. Gando🇯🇵 · H. Ikeda🇯🇵 · K. Inoue🇯🇵 · Y. Kishimoto🇯🇵 · M. Koga🇯🇵 · T. Mitsui🇯🇵 · K. Nakamura🇯🇵 and 45 other authors

   We describe a compact, ultra-clean device used to deploy radioactive sources along the vertical axis of the KamLAND liquid-scintillator neutrino detector for purposes of calibration. The device worked by paying out and reeling in precise lengths of a hanging, small-gauge wire rope (cable); an assortment of interchangeable radioactive sources could be attached to a weight at the end of the cable. All components exposed to the radiopure liquid scintillator were made of chemically compatible UHV-cleaned materials, primarily stainless steel, in order to avoid contaminating or degrading the scintillator. To prevent radon intrusion, the apparatus was enclosed in a hermetically sealed housing inside a glove box, and both volumes were regularly flushed with purified nitrogen gas. An infrared camera attached to the side of the housing permitted real-time visual monitoring of the cable's motion, and the system was controlled via a graphical user interface.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2015)·14 citations
6. 06*

   Power Counting of Contact-Range Currents in Effective Field Theory

   M. Pavón Valderrama🇫🇷 · Daniel R. Phillips🇺🇸

   We analyze the power counting of two-body currents in nuclear effective field theories (EFTs). We find that the existence of non-perturbative physics at low energies, which is manifest in the existence of the deuteron and the 1S0 NN virtual bound state, combined with the appearance of singular potentials in versions of nuclear EFT that incorporate chiral symmetry, modifies the renormalization-group flow of the couplings associated with contact operators that involve nucleon-nucleon pairs and external fields. The order of these couplings is thereby enhanced with respect to the naive-dimensional-analysis estimate. Consequently, short-range currents enter at a lower order in the chiral EFT than has been appreciated up until now, and their impact on low-energy observables is concomitantly larger. We illustrate the changes in the power counting with a few low-energy processes involving external probes and the few-nucleon systems, including electron-deuteron elastic scattering and radiative neutron capture by protons.

   ↳ nucl-thhep-phnucl-exPRL(2015)·80 citations
7. 07*

   Nature of isomerism in exotic sulfur isotopes

   Yutaka Utsuno🇯🇵 · Noritaka Shimizu🇯🇵 · Takaharu Otsuka🇯🇵 · Tooru Yoshida🇯🇵 · Yusuke Tsunoda🇯🇵

   We clarify the origin of the anomalously hindered $E2$ decay from the $4_1^{+}$ level in ${}^{44}$S by performing a novel many-body analysis in the shell model. Within a unified picture about the occurrence of isomerism in neutron-rich sulfur isotopes, the $4_1^{+}$ state is demonstrated to be a $K=4$ isomer dominated by the two-quasiparticle configuration $\nu {\Omega }^{\pi }=1/2^{-}\otimes \nu {\Omega }^{\pi }=7/2^{-}$. The $4_1^{+}$ state in ${}^{44}$S is a new type of high-$K$ isomer which has significant triaxiality.

   ↳ nucl-thnucl-exPRL(2015)·45 citations
8. 08*

   Optimizing relativistic energy density functionals: covariance analysis

   Tamara Niksic🇭🇷 · Nils Paar🇭🇷 · Paul-Gerhard Reinhard🇩🇪 · Dario Vretenar🇭🇷

   The stability of model parameters for a class of relativistic energy density functionals, characterized by contact (point-coupling) effective inter-nucleon interactions and density-dependent coupling parameters, is analyzed using methods of statistical analysis. A set of pseudo-observables in infinite and semi-infinite nuclear matter is used to define a quality measure ${\chi }^2$ for subsequent analysis. We calculate uncertainties of model parameters and correlation coefficients between parameters, and determine the eigenvectors and eigenvalues of the matrix of second derivatives of ${\chi }^2$ at the minimum. This allows to examine the stability of the density functional in nuclear matter, and to deduce weakly and strongly constrained combinations of parameters. In addition, we also compute uncertainties of observables that are not included in the calculation of ${\chi }^2$: binding energy of asymmetric nuclear matter, surface thickness of semi-infinite nuclear matter, binding energies and charge radii of finite nuclei.

   ↳ nucl-thnucl-exJ.Phys.G(2015)·19 citations
9. 09*

   System-size and energy dependence of particle momentum spectra: The UrQMD analysis of p+p and Pb+Pb collisions

   V.Yu. Vovchenko🇺🇦 · D.V. Anchishkin🇺🇦 · M.I. Gorenstein🇺🇦

   The UrQMD transport model is used to study a system-size and energy dependence of the pion production in high energy collisions. New data of the NA61/SHINE Collaboration on spectra of negatively charged pions in proton-proton interactions at SPS energies are considered. These results are compared with the corresponding data of the NA49 Collaboration in central Pb+Pb collisions at the same collision energies per nucleon. Mean pion multiplicity per participant nucleon, inverse slope parameter of the transverse momentum spectra, and width of rapidity distribution are investigated. A role of isospin effects is discussed. We find that the UrQMD model predicts a non-monotonous behavior of mean transverse mass with collision energy for positively charged pions at the mid-rapidity in inelastic proton-proton interactions. This will be checked soon experimentally by NA61/SHINE Collaboration.

   ↳ nucl-thhep-phnucl-exPRC(2014)·19 citations
10. 10*

    Using the Single Quark Transition Model to predict nucleon resonance amplitudes

    G. Ramalho🇧🇷

    We present predictions for the ${\gamma }^{\ast }N\to N^{\ast }$ helicity amplitudes, where $N^{\ast }$ is a member of the $[70,1^{-}]$ supermultiplet. We combine the results from the single quark transition model for the helicity amplitudes with the results of the covariant spectator quark model for the ${\gamma }^{\ast }N\to N^{\ast }(1535)$ and ${\gamma }^{\ast }N\to N^{\ast }(1520)$ transitions. The theoretical estimations from the covariant spectator quark model are used to calculate three independent functions $A,B$, and $C$ of $Q^2$, where $Q^2=-q^2$ and $q$ is the momentum transfer. With the knowledge of the functions $A,B$, and $C$ we estimate the helicity amplitudes for the transitions ${\gamma }^{\ast }N\to N^{\ast }(1650)$, ${\gamma }^{\ast }N\to N^{\ast }(1700)$, ${\gamma }^{\ast }N\to \Delta (1620)$, and ${\gamma }^{\ast }N\to \Delta (1700)$. The analysis is restricted to reactions with proton targets. The predictions for the transition amplitudes are valid for $Q^2>2$ GeV${}^2$.

    ↳ hep-phhep-exhep-latnucl-ex+1PRD(2014)·26 citations
11. 11*

    A recipe for EFT uncertainty quantification in nuclear physics

    R.J. Furnstahl🇺🇸 · D.R. Phillips🇺🇸 · S. Wesolowski🇺🇸

    The application of effective field theory (EFT) methods to nuclear systems provides the opportunity to rigorously estimate the uncertainties originating in the nuclear Hamiltonian. Yet this is just one source of uncertainty in the observables predicted by calculations based on nuclear EFTs. We discuss the goals of uncertainty quantification in such calculations and outline a recipe to obtain statistically meaningful error bars for their predictions. We argue that the different sources of theory error can be accounted for within a Bayesian framework, as we illustrate using a toy model.

    ↳ nucl-thhep-phnucl-exphysics.data-anJ.Phys.G(2015)·156 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.