Fri·Nov 20, 2015Friday·November 20, 2015

1. 01*

   Measurement of the transverse single-spin asymmetry in $p^{\uparrow }+p\to W^{\pm }/Z^0$ at RHIC

   STAR Collaboration: L. Adamczyk🇵🇱 · J. K. Adkins🇺🇸 · G. Agakishiev🇷🇺 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · I. Alekseev🇷🇺 · A. Aparin🇷🇺 · D. Arkhipkin🇺🇸 · E. C. Aschenauer🇺🇸 · A. Attri🇮🇳 · G. S. Averichev🇷🇺 · X. Bai🇨🇳 and 324 other authors

   We present the measurement of the transverse single-spin asymmetry of weak boson production in transversely polarized proton-proton collisions at $\sqrt{s}=500\text{GeV}$ by the STAR experiment at RHIC. The measured observable is sensitive to the Sivers function, one of the transverse momentum dependent parton distribution functions, which is predicted to have the opposite sign in proton-proton collisions from that observed in deep inelastic lepton-proton scattering. These data provide the first experimental investigation of the non-universality of the Sivers function, fundamental to our understanding of QCD.

   nucl-exhep-exPRL(2016)·151 citations
2. 02*

   Event by Event Analysis of High Multiplicity Events Produced in 158 A GeV/c 208 Pb- 208 Pb Collisions

   Shakeel Ahmad🇮🇳 · Anuj Chandra🇮🇳 · Ashwini Kumar🇮🇳 · O. S. K. Chaturvedi🇮🇳 · A. Ahmad🇮🇳 · M. Zafar🇮🇳 · M. Irfan🇮🇳 · B. K. Singh🇮🇳

   An extensive analysis of individual high multiplicity events produced in 158 A GeV /c 208Pb- 208Pb collisions is carried by adopting different methods to examine the anomalous behavior of these rare events. A method of selecting the events with densely populated narrow regions or spikes out of a given sample of collision events is discussed.Employing this approach two events with large spikes in their eta- and phi- distributions are selected for further analysis. For the sake of comparison, another two events which do not exhibit such spikes are simultaneously analyzed. The findings suggest that the systematic studies of particle density fluctuations in one- and two-dimensional phase-spaces and comparison with those obtained from the studies of correlation free Monte Carlo events, would be useful for identifying the events with large dynamical fluctuations. Formation of clusters or jet like phenomena in multihadronic final states in individual events is also discussed and the experimental findings are compared with the independent particle emission hypothesis by carrying out Monte Carlo simulations.

   nucl-exEPL(2015)·8 citations
3. 03*

   QCD Evolution of Superfast Quarks

   Adam J. Freese🇺🇸 · Wim Cosyn🇧🇪 · Misak M. Sargsian🇺🇸

   Recent high-precision measurements of nuclear deep inelastic scattering at high x and moderate 6 < Q${}^2$ < 9GeV${}^2$ give a rare opportunity to reach the quark distributions in the {\it superfast} region, in which the momentum fraction of the nucleon carried by its constituent quark is larger than the total fraction of the nucleon at rest, x>1. We derive the leading-order QCD evolution equation for such quarks with the goal of relating the moderate-Q${}^2$ data to the two earlier measurements of superfast quark distributions at large 60 < Q${}^2$ < 200~GeV${}^2$. Since the high-Q${}^2$ measurements gave strongly contradictory estimates of the nuclear effects that generate superfast quarks, relating them to the high-precision, moderate-Q${}^2$ data through QCD evolution allows us to clarify this longstanding issue. Our calculations indicate that the moderate-Q${}^2$ data at $x\lesssim 1.05$ are in better agreement with the high-Q${}^2$ data measured in (anti)neutrino-nuclear reactions which require substantial high-momentum nuclear effects in the generation of superfast quarks. Our prediction for the high-Q${}^2$ and x>1.1 region is somewhat in the middle of the neutrino-nuclear and muon-nuclear scattering data.

   ↳ hep-phnucl-exnucl-thPRD(2019)·12 citations
4. 04*

   Production of W-bosons in p-Pb collisions measured with ALICE at the LHC

   Edith Zinhle Buthelezi (for the ALICE Collaboration)🇿🇦

   W bosons are produced in hard scattering processes of partons in collisions of hadrons and they do not interact strongly with the medium produced in high-energy heavy-ion collisions. Therefore, in p-Pb collisions the measurement of W-boson yields represents a standard candle to check the validity of binary-collision scaling and can provide important constraints on the parton distribution functions, which can be modified in nuclei with respect to protons or neutrons. At the LHC, ALICE (A Large Ion Collider Experiment) is dedicated to the study of ultrarelativistic heavy-ion collisions, in which a hot and dense strongly-interacting medium is formed. At forward rapidities ALICE is equipped with a muon spectrometer that allows measurements of dimuon decays of quarkonia, muons from heavy-flavour hadron decays and also W bosons via their single-muon decay. In ALICE W-boson cross sections were measured in p-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV via the contribution of their muonic decays to the inclusive $p_{\mathrm{T}}$-differential muon yield measured at forward (2.03 < $y_{cms}$ < 3.53) and backward rapidity (-4.46 < $y_{cms}$ < -2.96) in various event-activity intervals. Recent results obtained from these measurements will be presented and the measured cross sections will be compared to perturbative Quantum Chromodynamics calculations at next-to-leading order.

   ↳ hep-exnucl-exPoS(2015)·1 citation
5. 05*

   The role of electron scattering from registration detector in a MAC-E type spectrometer

   P.V. Grigorieva🇷🇺 · A.A. Nozik🇷🇺 · V.S. Pantuev🇷🇺 · A.K. Skasyrskaya🇷🇺

   There is a proposal to search for a sterile neutrino in a few keV mass range by the "Troitsk nu-mass" facility. In order to estimate sterile neutrino mixing one needs to make precision spectrum measurements well below the endpoint using the existing electrostatic spectrometer with a magnetic adiabatic collimation, or MAC-E filter. The expected signature will be a kink in the electron energy spectrum in tritium beta-decay. In this article we consider the systematic effect of electron backscattering on the detector used in the spectrometer. For this purpose we provide a set of Monte-Carlo simulation results of electron backscattering on a silicon detector with a thin golden window with realistic electric and magnetic fields in the spectrometer. We have found that the probability of such an effect reaches up to 20-30\%. The scattered electron could be reflected backwards to the detector by electrostatic field or by magnetic mirror. There is also a few percent probability to escape from the spectrometer through its entrance. A time delay between the scattering moment on the detector and the return of the reflected electron can reach a couple of microseconds in the Troitsk spectrometer. Such estimations are critical for the planning upgrades of the detector and the registration electronics.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2016)·5 citations
6. 06*

   J/$\psi$ and $\psi$(2S) production in p-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV with ALICE at the LHC

   Marco Leoncino (for the ALICE Collaboration)🇮🇹

   The ALICE Collaboration has studied the inclusive J/$\psi$ and $\psi (2S)$ production in p-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV, at the CERN LHC. The J/$\psi$ measurement is performed in the ${\mu }^{+}{\mu }^{-}$ and in the $e^{+}{e}^{-}$ decay channels, down to zero $p_{\mathrm{T}}$. The results are in fair agreement with theoretical predictions. The $\psi (2S)$ measurement has also been performed. In particular, a smaller $\psi (2S)$ nuclear modification factor, with respect to the J$/\psi$ one, has been observed.

   ↳ hep-exnucl-exNuovo Cim.C(2015)·2 citations
7. 07*

   Shape coexistence in the microscopically guided interacting boson model

   K. Nomura🇫🇷 · T. Otsuka🇯🇵 · P. Van Isacker🇫🇷

   Shape coexistence has been a subject of great interest in nuclear physics for many decades. In the context of the nuclear shell model, intruder excitations may give rise to remarkably low-lying excited $0^{+}$ states associated with different intrinsic shapes. In heavy open-shell nuclei, the dimension of the shell-model configuration space that includes such intruder excitations becomes exceedingly large, thus requiring a drastic truncation scheme. Such a framework has been provided by the interacting boson model (IBM). In this article we address the phenomenon of shape coexistence and its relevant spectroscopy from the point of view of the IBM. A special focus is placed on the method developed recently which makes use of the link between the IBM and the self-consistent mean-field approach based on the nuclear energy density functional. The method is extended to deal with various intruder configurations associated with different equilibrium shapes. We assess the predictive power of the method and suggest possible improvements and extensions, by considering illustrative examples in the neutron-deficient Pb region, where shape coexistence has been experimentally studied.

   ↳ nucl-thnucl-exJ.Phys.G(2016)·49 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.