Thu·Sep 22, 2016Thursday·September 22, 2016

1. 01*

   Phenomenological Implications of the $p_T$ Spectra of $\varphi$ and $\Omega$ produced at LHC and RHIC

   Rudolph C. Hwa🇺🇸 · Lilin Zhu🇨🇳

   The data on the $p_T$ spectra of $\varphi$ and $\Omega$ at LHC can be presented in a format that shows exponential behavior up to $p_T\approx 6$ GeV/c with the same slope for both particles and for nearly all centralities. They are empirical properties that are shared at lower energies with the inverse slope showing a power-law dependence on $\sqrt{s_{NN}}$. The shared properties of the spectra are shown to emerge naturally from the recombination model. No flow is needed. We find experimental hints for the possibility that $\varphi$ and $\Omega$ are mostly produced in the ridge that are generated by minijets. Appropriate experimental test is suggested.

   nucl-exnucl-thJ.Phys.Conf.Ser.(2017)·4 citations
2. 02*

   First LHCb results from pA and Pb-Pb collisions

   L. Massacrier · LHCb collaboration

   In 2015, the LHCb collaboration endorsed the proposal to pursue an ambitious heavy-ion physics program. In 2013, LHCb has demonstrated its capabilities to operate successfully in p-Pb and Pb-p collisions, leading already to several important publications in the field. The measurements of the nuclear modification factor and forward-backward production of prompt and displaced J/$\psi$, $\psi$(2S) and ${\rm Y}$(1S) states, as well as the production of prompt $D^0$ mesons, have allowed to extend the knowledge of Cold Nuclear Matter effects on open heavy flavours and quarkonium production. The measurement of Z-boson production, important to constrain nuclear PDFs, and the measurement of two-particle angular correlations, probing collective effects in the dense environment of high energy collisions, have also been performed. Furthermore, LHCb is the only experiment at the LHC that can be operated in fixed-target mode, owing to the injection of a small amount of gas inside the LHCb collision area. There have been several p-gas and Pb-gas data taking periods during Run 1 and beginning of Run 2. This fixed target programme is conducted at a center-of-mass energy of $\mathcal{O}$(100 GeV), and has great potential to bridge the gap of knowledge between SPS and RHIC in the domain of Quark Gluon Plasma physics. Finally, LHCb successfully participated to its first Pb-Pb data taking at the end of 2015. First studies show that up to semi-central Pb-Pb collisions can be successfully analysed to provide unique measurements in the forward region. In this proceeding, we will present a selection of LHCb results in pA collisions. We will also give some prospects for fixed target and Pb-Pb studies.

   nucl-exhep-exPoS(2016)·3 citations
3. 03*

   Measurement of the relative yields of $\psi (2S)$ to $\psi (1S)$ mesons produced at forward and backward rapidity in $p$$+$$p$, $p$$+$Al, $p$$+$Au, and ${}^3$He$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV

   A. Adare🇺🇸 · C. Aidala🇺🇸 · N.N. Ajitanand🇺🇸 · Y. Akiba🇯🇵 · M. Alfred🇺🇸 · V. Andrieux🇺🇸 · K. Aoki🇯🇵 · N. Apadula🇺🇸 · H. Asano🇯🇵 · C. Ayuso🇺🇸 · B. Azmoun🇺🇸 · V. Babintsev🇷🇺 and 350 other authors

   The PHENIX Collaboration has measured the ratio of the yields of $\psi (2S)$ to $\psi (1S)$ mesons produced in $p$$+$$p$, $p$$+$Al, $p$$+$Au, and ${}^3$He$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV over the forward and backward rapidity intervals $1.2<|y|<2.2$. We find that the ratio in $p$$+$$p$ collisions is consistent with measurements at other collision energies. In collisions with nuclei, we find that in the forward ($p$-going or ${}^3$He-going) direction, the relative yield of $\psi (2S)$ mesons to $\psi (1S)$ mesons is consistent with the value measured in \pp collisions. However, in the backward (nucleus-going) direction, the $\psi (2S)$ is preferentially suppressed by a factor of $\sim$2. This suppression is attributed in some models to breakup of the weakly-bound $\psi (2S)$ through final state interactions with comoving particles, which have a higher density in the nucleus-going direction. These breakup effects may compete with color screening in a deconfined quark-gluon plasma to produce sequential suppression of excited quarkonia states.

   nucl-exPRC(2017)·60 citations
4. 04*

   Anomalous evolution of the near-side jet peak shape in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV

   ALICE Collaboration

   The measurement of two-particle angular correlations is a powerful tool to study jet quenching in a $p_{\mathrm{T}}$ region inaccessible by direct jet identification. In these measurements pseudorapidity ($\Delta \eta$) and azimuthal ($\Delta \phi$) differences are used to extract the shape of the near-side peak formed by particles associated to a higher $p_{\mathrm{T}}$ trigger particle ($1<p_{\mathrm{T},\mathrm{trig}}<$ 8 GeV/c). A combined fit of the near-side peak and long-range correlations is applied to the data allowing the extraction of the centrality evolution of the peak shape in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV. A significant broadening of the peak in the $\Delta \eta$ direction at low $p_{\mathrm{T}}$ is found from peripheral to central collisions, which vanishes above 4 GeV/c, while in the $\Delta \phi$ direction the peak is almost independent of centrality. For the 10% most central collisions and $1<p_{\mathrm{T},\mathrm{assoc}}<$ 2 GeV/c, $1<p_{\mathrm{T},\mathrm{trig}}<$ 3 GeV/c a novel feature is observed: a depletion develops around the centre of the peak. The results are compared to pp collisions at the same centre of mass energy and to AMPT model simulations. The comparison to the investigated models suggests that the broadening and the development of the depletion is connected to the strength of radial and longitudinal flow.

   nucl-exhep-exPRL(2017)·31 citations
5. 05*

   Temperature dependence of the probability of "small heating" and spectrum of UCNs up-scattered on the surface of Fomblin oil Y-HVAC 18/8

   V.V. Nesvizhevsky🇫🇷 · A.Yu. Voronin🇷🇺 · A. Lambrecht · S. Reynaud🇫🇷 · E.V. Lychagin🇷🇺 · A.Yu. Muzychka🇷🇺 · G.V. Nekhaev🇷🇺 · A.V. Strelkov🇷🇺

   We performed precision measurements of the probability of small heating and spectrum of UCNs up-scattered on the surface of hydrogen-free oil Fomblin Y-HVAC 18/8 as a function of temperature. The probability is well reproducible, does not depend on sample thickness and does not evolve in time. It is equal (9.8+-0.2)10^(-6) at the ambient temperature. The spectrum coincides with those measured with solid-surface and nanoparticle samples. Indirect arguments indicate that spectrum shape weakly depends on temperature. Measured experimental data can be satisfactory described both within the model of near-surface nanodroplets and the model of capillary waves.

   ↳ physics.ins-detnucl-ex0 citations
6. 06*

   Coupled-channels description of the 40Ca+58,64Ni transfer and fusion reactions

   G. Scamps🇯🇵 · D. Bourgin🇫🇷 · K. Hagino🇯🇵 · F. Haas🇫🇷 · S. Courtin🇫🇷

   Preliminary experimental data for nucleon transfer reactions of the 40Ca+58Ni and 40Ca+64Ni systems are analyzed with the coupled- channels approach. It is shown that a simple treatment for the transfer in the coupled-channels method cannot reproduce simultaneously the transfer probabilities and the sub-barrier enhancement of fusion cross sections.

   ↳ nucl-thnucl-exNuovo Cim.C(2017)·1 citation
7. 07*

   Medium effects on heavy-flavour observables in high-energy nuclear collisions

   Andrea Beraudo🇮🇹

   The peculiar role of heavy-flavour observables in relativistic heavy-ion collisions is discussed. Produced in the early stage, $c$ and $b$ quarks cross the hot medium arising from the collision, interacting strongly with the latter, until they hadronize. Depending on the strength of the interaction heavy quarks may or not approach kinetic equilibrium with the plasma, tending in the first case to follow the collective flow of the expanding fireball. The presence of a hot deconfined medium may also affect heavy-quark hadronization, being possible for them to recombine with the surrounding light thermal partons, so that the final heavy-flavour hadrons inherit part of the flow of the medium. Here we show how it is possible to develop a complete transport setup allowing one to describe heavy-flavour production in high-energy nuclear collisions, displaying some major results one can obtain. Finally, the possibility that the formation of a hot deconfined medium even in small systems (high-multiplicity p-Au and d-Au collisions, so far) may affect also heavy-flavour observables is investigated.

   ↳ nucl-thhep-phnucl-exEPJ Web Conf.(2016)·1 citation
8. 08*

   Systematic study on probable projectile-target combinations for the synthesis of the ${}^{302}$120 superheavy nucleus

   K. P. Santhosh🇮🇳 · V. Safoora

   Probable projectile-target combinations for the synthesis of superheavy element ${}^{302}$120 have been studied taking Coulomb and proximity potential as the interaction barrier. The probabilities of compound nucleus formation, PCN for the projectile-target combinations found in the cold reaction valley of ${}^{302}$120 are estimated. At energies near and above the Coulomb barrier, we have calculated the capture, fusion and evaporation residue cross sections for the reactions of all the probable projectile-target combinations so as to predict the most promising projectile-target combinations for the synthesis of SHE ${}^{302}$120 in heavy ion fusion reactions. The calculated fusion and evaporation cross section for the more asymmetric (hotter) projectile-target combination is found to be higher than the less asymmetric (colder) combination. It can be seen from the nature of quasi-fission barrier height, mass asymmetry, probability of compound nucleus formation, survival probability and excitation energy, the systems ${}^{44}$Ar + ${}^{258}$No, ${}^{46}$Ar + ${}^{256}$No, ${}^{48}$Ca + ${}^{254}$Fm, ${}^{50}$Ca + ${}^{252}$Fm, ${}^{54}$Ti + ${}^{248}$Cf, ${}^{58}$Cr + ${}^{244}$Cm in the deep region I of cold reaction valley, and the systems ${}^{62}$Fe + ${}^{240}$Pu, ${}^{64}$Fe + ${}^{238}$Pu, ${}^{68}$Ni + ${}^{234}$U, ${}^{70}$Ni + ${}^{232}$U, ${}^{72}$Ni + ${}^{230}$U, ${}^{74}$Zn + ${}^{228}$Th in the other cold valleys are identified as the better projectile-target combinations for the synthesis of ${}^{302}$120. Our prediction on the synthesis of ${}^{302}$120 superheavy nuclei using the combinations ${}^{54}$Cr+${}^{248}$Cm, ${}^{58}$Fe+${}^{244}$Pu, ${}^{64}$Ni+${}^{238}$U and ${}^{50}$Ti+${}^{249}$Cf are compared with available experimental data and other theoretical predictions.

   ↳ nucl-thnucl-exPRC(2016)·21 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.