Tue·May 24, 2016Tuesday·May 24, 2016

1. 01*

   Multiplicity and rapidity dependence of strange hadron production in pp, pPb, and PbPb collisions at the LHC

   CMS Collaboration

   Measurements of strange hadron (K0s, Lambda + anti-Lambda, and Xi+ + Xi-) transverse momentum spectra in pp, pPb, and PbPb collisions are presented over a wide range of rapidity and event charged-particle multiplicity. The data were collected with the CMS detector at the CERN LHC in pp collisions at sqrt(s) = 7 TeV, pPb collisions at sqrt(s[NN]) = 5.02 TeV, and PbPb collisions at sqrt(s[NN]) = 2.76 TeV. The average transverse kinetic energy is found to increase with multiplicity, at a faster rate for heavier strange particle species in all systems. At similar multiplicities, the difference in average transverse kinetic energy between different particle species is observed to be larger for pp and pPb events than for PbPb events. In pPb collisions, the average transverse kinetic energy is found to be slightly larger in the Pb-going direction than in the p-going direction for events with large multiplicity. The spectra are compared to models motivated by hydrodynamics.

   nucl-exhep-exPLB(2017)·109 citations
2. 02*

   Measurement of azimuthal correlations of D mesons and charged particles in pp collisions at $\sqrt{s}=7$ TeV and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   ALICE Collaboration

   The azimuthal correlations of D mesons and charged particles were measured with the ALICE detector in pp collisions at $\sqrt{s}=7$ TeV and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV at the Large Hadron Collider. D${}^0$, D${}^{+}$, and D${}^{\ast +}$ mesons and their charge conjugates with transverse momentum $3<p_{\mathrm{T}}<16$ GeV/$c$ and rapidity in the nucleon-nucleon centre-of-mass system $|y_{\mathrm{cms}}|<0.5$ (pp collisions) and $-0.96<y_{\mathrm{cms}}<0.04$ (p-Pb collisions) were correlated to charged particles with $p_{\mathrm{T}}>0.3$ Gev/$c$. The properties of the correlation peak induced by the jet containing the D meson, described in terms of the yield of charged particles in the peak and peak width, are compatible within uncertainties between the two collision systems, and described by Monte-Carlo simulations based on the PYTHIA, POWHEG and EPOS 3 event generators.

   nucl-exhep-exEPJC(2017)·68 citations
3. 03*

   Coherent J/psi photoproduction in ultra-peripheral PbPb collisions at sqrt(s[NN]) = 2.76 TeV with the CMS experiment

   CMS Collaboration

   The cross section for coherent J/psi photoproduction accompanied by at least one neutron on one side of the interaction point and no neutron activity on the other side, X[n]0[n], is measured with the CMS experiment in ultra-peripheral PbPb collisions at sqrt(s[NN]) = 2.76 TeV. The analysis is based on a data sample corresponding to an integrated luminosity of 159 inverse microbarns, collected during the 2011 PbPb run. The J/psi mesons are reconstructed in the dimuon decay channel, while neutrons are detected using zero degree calorimeters. The measured cross section is dsigma[coh,X[n]0[n]] / dy(J/psi) = 0.36 +/- 0.04 (stat) +/- 0.04 (syst) mb in the rapidity interval 1.8 < abs(y) < 2.3. Using a model for the relative rate of coherent photoproduction processes, this X[z,n,z] measurement gives a total coherent photoproduction cross section of dsigma[coh] / dy(J/psi) = 1.82 +/- 0.22 (stat) +/- 0.20 (syst) +/- 0.19 (theo) mb. The data strongly disfavour the impulse approximation model prediction, indicating that nuclear effects are needed to describe coherent J/psi photoproduction in gamma + Pb interactions. The data are found to be consistent with the leading twist approximation, which includes nuclear gluon shadowing.

   nucl-exhep-exPLB(2017)·206 citations
4. 04*

   Completing the nuclear reaction puzzle of the nucleosynthesis of 92Mo

   G. M. Tveten🇳🇴 · A. Spyrou🇺🇸 · R. Schwengner🇩🇪 · F. Naqvi🇺🇸 · A. C. Larsen🇳🇴 · T. K. Eriksen🇳🇴 · F. L. Bello Garrote🇳🇴 · L. A. Bernstein🇺🇸 · D. L. Bleuel🇺🇸 · L. Crespo Campo🇳🇴 · M. Guttormsen🇳🇴 · F. Giacoppo🇳🇴 and 11 other authors

   One of the greatest questions for modern physics to address is how elements heavier than iron are created in extreme, astrophysical environments. A particularly challenging part of that question is the creation of the so-called p-nuclei, which are believed to be mainly produced in some types of supernovae. The lack of needed nuclear data presents an obstacle in nailing down the precise site and astrophysical conditions. In this work, we present for the first time measurements on the nuclear level density and average strength function of ${}^{92}$Mo. State-of-the-art p-process calculations systematically underestimate the observed solar abundance of this isotope. Our data provide stringent constraints on the ${}^{91}$Nb$(p,\gamma {)}^{92}$Mo reaction rate, which is the last unmeasured reaction in the nucleosynthesis puzzle of ${}^{92}$Mo. Based on our results, we conclude that the ${}^{92}$Mo abundance anomaly is not due to the nuclear physics input to astrophysical model calculations.

   nucl-exPRC(2016)·17 citations
5. 05*

   An Optimal Energy Estimator to Reduce Correlated Noise for the EXO-200 Light Readout

   EXO-200 Collaboration: C.G. Davis🇺🇸 · C. Hall🇺🇸 · J.B. Albert🇺🇸 · P.S. Barbeau🇺🇸 · D. Beck🇺🇸 · V. Belov🇷🇺 · M. Breidenbach🇺🇸 · T. Brunner🇨🇦 · A. Burenkov🇷🇺 · G.F. Cao🇨🇳 · W.R. Cen🇨🇳 · C. Chambers🇺🇸 and 74 other authors

   The energy resolution of the EXO-200 detector is limited by electronics noise in the measurement of the scintillation response. Here we present a new technique to extract optimal scintillation energy measurements for signals split across multiple channels in the presence of correlated noise. The implementation of these techniques improves the energy resolution of the detector at the neutrinoless double beta decay Q-value from $\left[1.9641\pm 0.0039\right]\%$ to $\left[1.5820\pm 0.0044\right]\%$.

   ↳ physics.ins-dethep-exnucl-exJINST(2016)·18 citations
6. 06*

   Mapping color fluctuations in the photon in ultraperipheral heavy ion collisions at the Large Hadron Collider

   M. Alvioli (Perugia U.)🇮🇹 · L. Frankfurt (Tel Aviv U. and Penn State U.)🇮🇱 · V. Guzey (PNPI)🇷🇺 · M. Strikman (Penn State U.)🇺🇸 · M. Zhalov (PNPI)🇷🇺

   We model effects of color fluctuations (CFs) in the light-cone photon wave function and for the first time make predictions for the distribution over the number of wounded nucleons $\nu$ in the inelastic photon-nucleus scattering. We show that CFs lead to a dramatic enhancement of this distribution at $\nu =1$ and large $\nu >10$. We also study the implications of different scales and CFs in the photon wave function on the total transverse energy $\Sigma E_T$ and other observables in inelastic $\gamma A$ scattering with different triggers. Our predictions can be tested in proton-nucleus and nucleus-nucleus ultraperipheral collisions at the LHC and will help to map CFs, whose first indications have already been observed at the LHC.

   ↳ hep-phhep-exnucl-exPLB(2017)·11 citations
7. 07*

   Probing Multi-Strange Dibaryon with Proton-Omega Correlation in High-energy Heavy Ion Collisions

   Kenji Morita🇯🇵 · Akira Ohnishi🇯🇵 · Faisal Etminan🇮🇷 · Tetsuo Hatsuda🇯🇵

   Two-particle intensity correlation between the proton ($p$) and the Omega-baryon ($\Omega$) in high-energy heavy ion collisions is studied to unravel the possible spin-2 $p\Omega$ dibaryon recently suggested by lattice QCD simulations. The ratio of correlation functions between small and large collision systems, $C_{\mathrm{SL}}(Q)$, is proposed to be a new measure to extract the strong $p\Omega$ interaction without much contamination from the Coulomb attraction. Relevance of this quantity to the experimental observables in heavy-ion collisions is also discussed.

   ↳ hep-phnucl-exnucl-thPRC(2016)·98 citations
8. 08*

   An octahedral deformation with six alpha particles at the Z = 12 system, Mg nuclides: Third nucleons, Alpharons

   Chang-Bum Moon

   We suggest that the emergence of a large deformation in the magnesium, Mg, nuclides, especially at the Z = 12, N = 12, should be associated with an octahedral deformed shape. Within the framework of molecular geometrical symmetry, we find a possibility that the Z = 12, N = 12 system would form an octahedral structure consisting of six points of alpha(4He) particles, yielding the ground collectivity. With this point of view, we draw the following serial molecular structures; the Z = 10, N = 10, 20Ne, corresponds to a hexahedral, the Z = 8, N = 8, 16O, does to a tetrahedral, and the Z = 6, N = 6, 12C, does to a trigonal symmetry. Moreover, the Z = 2, N = 2, 4He(alpha), fits into a tetrahedral symmetry with four points of nucleons; two protons and two neutrons. The enhanced deformation at Z = 12 with N > 20 would be explained by a deformed shape related to an Ethene(Ethylene)-like skeleton with six alpha particles. The deformation at Z = 10, with N = 10 and 12, can be interpreted as being attributed to a hexahedral shape combined by five alpha particles as well. By noticing that the Z = 4, N = 4 system is unstable to the ground state under two-body system with two alpha particles, we conclude that alpha particles, rather than the eight-protons-neutrons nucleon, govern the 8Be stability. Accordingly, the alpha particle should be a third nucleon, like a proton or a neutron, in a nucleus. We name it the 'Alpharon'. With this picture, we are able to open a new gate toward understanding of nuclear many-body systems; nucleon-nucleon interaction, shell structures, nucleon-synthesis, and nuclear matters. We argue that nature favors three-body systems; three quarks for a nucleon, three nucleons for a nucleus.

   ↳ nucl-thnucl-ex0 citations
9. 09*

   Single electron multiplication distribution in GEM avalanches

   Andras Laszlo🇭🇺 · Gergo Hamar🇮🇹 · Gabor Kiss🇭🇺 · Dezso Varga🇭🇺

   In this paper, measurement results and experimental methodology are presented on the determination of multiplication distributions of avalanches initiated by single electron in GEM foils. The measurement relies on the amplification of photoelectrons by the GEM under study, which is subsequently amplified in an MWPC for signal enhancement and readout. The intrinsic detector resolution, namely the sigma-over-mean ratio of the multiplication. distribution is also elaborated. Small gain dependence of the shape of the avalanche response distribution is observed in the range of net effective gain of 15 to 100. The distribution has an exponentially decaying tail at large amplitudes. At small amplitudes, the applied working gas is seen to have a well visible effect on the shape of the multiplication distribution. Equivalently, the working gas has an influence on the intrinsic detector resolution of GEMs via suppression of the low amplitude responses. A sigma-over-mean ratio of 0.75 was reached using a neon based mixture, whereas other gases provided an intrinsic detector resolution closer to 1, meaning a multiplication distribution closer to the low-field limit exponential case.

   ↳ physics.ins-dethep-exnucl-exJINST(2016)·7 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.