Thu·Oct 9, 2014Thursday·October 9, 2014

1. 01*

   Search for "Ridge" in d+Au Collisions at RHIC by STAR

   Li Yi for STAR Collaboration🇺🇸

   Dihadron correlations are measured in d+Au collisions at 200 GeV by the STAR detector. The correlated yields with uniform background subtraction are studied in high- and low-multiplicity collisions. The effects of multiplicity selection bias on jet-like correlations are discussed. Finite correlated yields are observed on the near-side at large pseudo-rapidity separation in high-multiplicity collisions.

   nucl-exNPA(2014)·5 citations
2. 02*

   Multi-strange baryon production in pp, p-Pb and Pb-Pb collisions measured with ALICE at the LHC

   Didier Alexandre (for the ALICE Collaboration)🇬🇧

   Multi-strange baryons are of particular interest in the understanding of particle production mechanisms, as their high strangeness content makes them susceptible to changes in the hadrochemistry of the colliding systems. In ALICE, these hyperons are reconstructed via the detection of their weak decay products, which are identified through their measured ionisation losses and momenta in the Time Projection Chamber. The production rates of charged $\Xi$ and $\Omega$ baryons in proton-proton (pp), proton-lead (p-Pb) and lead-lead (Pb-Pb) collisions are reported as a function of $p_{\mathrm{T}}$. A direct comparison in the hyperon-to-pion ratios between the three collision systems is made as a function of event charged-particle multiplicity. The recently measured production rates in p-Pb interactions reveal an enhancement with increasing event multiplicity, consistent with a hierarchy dependent on the strangeness content of the hyperons. These results are discussed in the context of chemical equilibrium predictions, taking into account the extracted temperature parameter from a thermal model fit to the hadron yields in Pb-Pb data.

   nucl-exhep-exNPA(2014)·6 citations
3. 03*

   New measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission

   K. B. Grammer🇺🇸 · R. Alarcon🇺🇸 · L. Barrón-Palos🇲🇽 · D. Blyth🇺🇸 · J. D. Bowman🇺🇸 · J. Calarco🇺🇸 · C. Crawford🇺🇸 · K. Craycraft🇺🇸 · D. Evans🇺🇸 · N. Fomin🇺🇸 · J. Fry🇺🇸 · M. Gericke🇨🇦 and 16 other authors

   Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many body physics. Unfortunately, the pair correlation function $g(r)$ inferred from neutron scattering measurements of the differential cross section $\frac{d\sigma }{d\Omega }$ from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43~meV and 16.1~meV on liquid hydrogen at 15.6~K (which is dominated by the parahydrogen component) using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1~meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra non-equilibrium component of orthohydrogen. Liquid parahydrogen is also a widely-used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. We describe our measurements and compare them with previous work.

   nucl-exphysics.ins-detPRB(2015)·20 citations
4. 04*

   Blast Wave Fits to Elliptic Flow Data at $\sqrt{s_{\mathrm{NN}}}=$ 7.7--2760 GeV

   X. Sun🇨🇳 · H. Masui🇯🇵 · A. M. Poskanzer🇺🇸 · A. Schmah🇺🇸

   We present blast wave fits to elliptic flow ($v_2(p_{\mathrm{T}})$) data in minimum bias collisions from the $\sqrt{s_{\mathrm{NN}}}=$ 7.7--200 GeV at RHIC, and 2.76 TeV at LHC. The fits are performed separately for particles and corresponding anti-particles. The mean transverse velocity parameter $\beta$ shows an energy dependent difference between particles and corresponding anti-particles, which increases as the beam energy decreases. Possible effects of feed down, baryon stopping, anti-particle absorption, and early production times for anti-particles are discussed.

   ↳ hep-phnucl-exnucl-thPRC(2015)·29 citations
5. 05*

   Spin physics and TMD studies at A Fixed-Target ExpeRiment at the LHC (AFTER@LHC)

   J.P. Lansberg🇫🇷 · M. Anselmino🇮🇹 · R. Arnaldi🇮🇹 · S.J. Brodsky🇺🇸 · V. Chambert🇫🇷 · W. den Dunnen🇩🇪 · J.P. Didelez🇫🇷 · B. Genolini🇫🇷 · E.G. Ferreiro🇪🇸 · F. Fleuret🇫🇷 · Y. Gao🇨🇳 · C. Hadjidakis🇫🇷 and 14 other authors

   We report on the opportunities for spin physics and Transverse-Momentum Dependent distribution (TMD) studies at a future multi-purpose fixed-target experiment using the proton or lead ion LHC beams extracted by a bent crystal. The LHC multi-TeV beams allow for the most energetic fixed-target experiments ever performed, opening new domains of particle and nuclear physics and complementing that of collider physics, in particular that of RHIC and the EIC projects. The luminosity achievable with AFTER@LHC using typical targets would surpass that of RHIC by more that 3 orders of magnitude in a similar energy region. In unpolarised proton-proton collisions, AFTER@LHC allows for measurements of TMDs such as the Boer-Mulders quark distributions, the distribution of unpolarised and linearly polarised gluons in unpolarised protons. Using the polarisation of hydrogen and nuclear targets, one can measure transverse single-spin asymmetries of quark and gluon sensitive probes, such as, respectively, Drell-Yan pair and quarkonium production. The fixed-target mode has the advantage to allow for measurements in the target-rapidity region, namely at large x^uparrow in the polarised nucleon. Overall, this allows for an ambitious spin program which we outline here.

   ↳ hep-exhep-phnucl-exnucl-thEPJ Web Conf.(2015)·29 citations
6. 06*

   Forward Hadron Productions in high energy pp collisions from a Monte-Carlo generator for Color Glass Condensate

   Wei-Tian Deng🇨🇳 · Hirotsugu Fujii🇯🇵 · Kazunori Itakura🇯🇵 · Yasushi Nara🇯🇵

   We develop a Monte-Carlo event generator based on combination of a parton production formula including the effects of parton saturation (called the DHJ formula) and hadronization process due to the Lund string fragmentation model. This event generator is designed for the description of hadron productions at forward rapidities and in a wide transverse momentum range in high-energy proton-proton collisions. We analyze transverse momentum spectra of charged hadrons as well as identified particles; pion, kaon, (anti-)proton at RHIC energy, and ultra-forward neutral pion spectra from LHCf experiment. We compare our results to those obtained in other models based on parton-hadron duality and fragmentation functions.

   ↳ hep-phnucl-exnucl-thPRD(2015)·7 citations
7. 07*

   Resonance dynamics in the coherent $\eta$ meson production in the $(p,p^{\prime })$ reaction on the spin-isospin saturated nucleus

   Swapan Das🇮🇳

   For the forward going proton and $\eta$ meson, the coherent $\eta$ meson production in the $(p,p^{\prime })$ reaction on the spin-isospin saturated nucleus occurs only due to the $\eta$ meson exchange interaction between the beam proton and nucleus. In this process, the nucleon in the nucleus can be excited to resonances $N^{\ast }$ and the $\eta$ meson in the final state can arise due to $N^{\ast }\to N\eta$. We investigate the dynamics of resonances, including nucleon Born terms, and their interferences in the coherently added cross section of this reaction. We discuss the importance of $N(1520)$ resonance and show the sensitivity of the cross section to the hadron nucleus interaction.

   ↳ nucl-thnucl-exPLB(2014)·4 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.