Wed·Oct 21, 2015Wednesday·October 21, 2015

1. 01*

   Measurement of D${}^{+}$ meson production in p-Pb collisions with the ALICE detector

   Riccardo Russo🇮🇹

   The main goal of the experimental programs on ultra-relativistic heavy ion collisions at the LHC is the production and characterization of the Quark Gluon Plasma (QGP), a phase of nuclear matter in which strongly interacting constituents (quarks and gluons) are deconfined. Heavy quarks are considered effective probes of the properties of the QGP as they are created on a short time scale, with respect to that of the QGP, and subsequently interact with it. Moreover, for a proper assessment of the characteristics of the matter produced in heavy-ion collisions, it is important to disentangle the final state effects due to the formation of a QGP from the initial state effects due to the fact that nuclei are present in the colliding system. Both initial and final state effects may lead to qualitatively similar phenomena in the observables of interest. The measurement of charmed meson production in proton-nucleus collisions allows to assess initial state effects present in nuclear collisions, under the assumption that an extended deconfined medium is not created in this kind of interactions. The nuclear modification factor of $D$ mesons in p-Pb collisions ($R_{\mathrm{pPb}}$) is essential for a complete understanding of the modification of $D$ mesons momentum distributions observed in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$= 2.76 TeV, which is interpreted as due to the $c$-quark energy loss in the medium. In addition, some of the results obtained from high-multiplicity p-Pb collisions at LHC, such as the ridge structure in the two-particle correlation function, turned out to be unexpected, and have been interpreted in terms of final state effects such as hydrodynamic flow. These aspects make a study of charmed meson production in p-Pb collisions as a function of the event multiplicity of great interest.

   nucl-ex18 citations
2. 02*

   Global Antineutrino Modeling for a Web Application

   Steve Dye🇺🇸 · Andrew Barna🇺🇸

   Antineutrinos stream freely from rapidly decaying fission products within the cores of nuclear reactors and from long-lived natural radioactivity within the rocky layers of the Earth. These global antineutrinos produce detectable signals in large ultra-clear volumes of water- or hydrocarbon-based target liquids, which are viewed by inward-facing photomultiplier tubes. Detected antineutrinos provide information about their shrouded sources and about the fundamental properties of neutrinos themselves. This paper presents the input data, formulae, and plots resulting from the calculations, which, in addition to the time-dependent reaction rates and energy spectra, model the directions of the antineutrinos from IAEA-registered nuclear power reactors and of the neutrinos from ${}^8$B decay in the Sun. The model includes estimates of the steady state reaction rates and energy spectra of the antineutrinos from the crust and mantle of the Earth. Results are available for any location near the surface of the Earth and comprise both quasi-elastic scattering on free protons and elastic scattering on atomic electrons. This paper compares model results for two underground locations, the Boulby Mine in the United Kingdom and the Morton Salt Mine in the United States. Operational nuclear power reactors are within about $20$ kilometers of these mines, making them candidate sites for antineutrino detectors capable of identifying, monitoring, and locating remote nuclear activity. The model, which is implemented in a web application at https://geoneutrinos.org/reactors/, provides references for the input data and the formulae, as well as an interactive calculator of the significance of the rate of any of the neutrino sources relative to other sources taken as background.

   ↳ physics.ins-detnucl-ex25 citations
3. 03*

   Model-independent determination of the axial mass parameter in quasielastic antineutrino-nucleon scattering

   Bhubanjyoti Bhattacharya🇨🇦 · Gil Paz🇺🇸 · Anthony J. Tropiano🇺🇸

   Understanding the charged current quasielestic (CCQE) neutrino-nucleus interaction is important for precision studies of neutrino oscillations. The theoretical description of the interaction depends on the combination of a nuclear model with the knowledge of form factors. While the former has received considerable attention, the latter, in particular the axial form factor, is implemented using the historical dipole model. Instead, we use a model-independent approach, presented in a previous study, to analyze the muon antineutrino CCQE mineral oil data published by the MiniBooNE collaboration. We combine the cross section for scattering of antineutrinos off protons in carbon and hydrogen, using the same axial form factor for both. The extracted value of the axial mass parameter $m_A=0.84_{-0.04}^{+0.12}\pm 0.11\mathrm{GeV}$ is in very good agreement with the model-independent value extracted from MiniBooNE's neutrino data. Going beyond a one-parameter description of the axial form factor, we extract values of the axial form factor in the range of $Q^2=\mathrm{0.1...1.0}$ GeV${}^2$, finding a very good agreement with the analogous extraction from the neutrino data. We discuss the implications of these results.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2015)·39 citations
4. 04*

   QGP formation time and the large photon v2 puzzle in heavy ion collisions

   Fu-Ming Liu🇨🇳

   We investigate the large photon v2 puzzle and the two time scales of thermal and chemical equilibrium in heavy ion collisions. The two-time-scale picture has a weak effect on the transverse moemntum spectrum of direct photons, but a strong effect on the elliptic flow of direct photons. Thus both the spectrum and the elliptic flow of direct photons may be explained with hydro evolution constrained with hadron data. In such a picture, a gluon dominant matter appears in heavy ion collisions. This new matter may impact strongly to other fields such as astrophysics and cosmology.

   ↳ hep-phnucl-exNucl.Part.Phys.Proc.(2016)·0 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.