Wed·Jul 1, 2015Wednesday·July 1, 2015

1. 01*

   Differential studies of inclusive J/$\psi$ and $\psi$(2S) production at forward rapidity in Pb-Pb collisions at $\sqrt{{\text{s}}_{{}_{\mathbf{NN}}}}$ = 2.76 TeV

   ALICE Collaboration

   The production of J/$\psi$ and $\psi (2S)$ was measured with the ALICE detector in Pb-Pb collisions at the LHC. The measurement was performed at forward rapidity ($2.5<y<4$) down to zero transverse momentum ($p_{\mathrm{T}}$) in the dimuon decay channel. Inclusive J/$\psi$ yields were extracted in different centrality classes and the centrality dependence of the average $p_{\mathrm{T}}$ is presented. The J/$\psi$ suppression, quantified with the nuclear modification factor ($R_{\mathrm{AA}}$), was studied as a function of centrality, transverse momentum and rapidity. Comparisons with similar measurements at lower collision energy and theoretical models indicate that the J/$\psi$ production is the result of an interplay between color screening and recombination mechanisms in a deconfined partonic medium, or at its hadronization. Results on the $\psi (2S)$ suppression are provided via the ratio of $\psi (2S)$ over J/$\psi$ measured in pp and Pb-Pb collisions.

   nucl-exhep-exJHEP(2016)·160 citations
2. 02*

   Centrality dependence of inclusive J/$\psi$ production in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

   ALICE Collaboration

   We present a measurement of inclusive J/$\psi$ production in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV as a function of the centrality of the collision, as estimated from the energy deposited in the Zero Degree Calorimeters. The measurement is performed with the ALICE detector down to zero transverse momentum, $p_{\mathrm{T}}$, in the backward ($-4.46<y_{\mathrm{cms}}<-2.96$) and forward ($2.03<y_{\mathrm{cms}}<3.53$) rapidity intervals in the dimuon decay channel and in the mid-rapidity region ($-1.37<y_{\mathrm{cms}}<0.43$) in the dielectron decay channel. The backward and forward rapidity intervals correspond to the Pb-going and p-going direction, respectively. The $p_{\mathrm{T}}$-differential J/$\psi$ production cross section at backward and forward rapidity is measured for several centrality classes, together with the corresponding average $p_{\mathrm{T}}$ and $p_{\mathrm{T}}^2$ values. The nuclear modification factor, $Q_{\mathrm{pPb}}$, is presented as a function of centrality for the three rapidity intervals, and, additionally, at backward and forward rapidity, as a function of $p_{\mathrm{T}}$ for several centrality classes. At mid- and forward rapidity, the J/$\psi$ yield is suppressed up to 40% compared to that in pp interactions scaled by the number of binary collisions. The degree of suppression increases towards central p-Pb collisions at forward rapidity, and with decreasing $p_{\mathrm{T}}$ of the J/$\psi$. At backward rapidity, the $Q_{\mathrm{pPb}}$ is compatible with unity within the total uncertainties, with an increasing trend from peripheral to central p-Pb collisions.

   nucl-exhep-exJHEP(2015)·116 citations
3. 03*

   Production of light nuclei and anti-nuclei in pp and Pb-Pb collisions at LHC energies

   ALICE Collaboration

   The production of (anti-)deuteron and (anti-)${}^3$He nuclei in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV has been studied using the ALICE detector at the LHC. The spectra exhibit a significant hardening with increasing centrality. Combined blast-wave fits of several particles support the interpretation that this behavior is caused by an increase of radial flow. The integrated particle yields are discussed in the context of coalescence and thermal-statistical model expectations. The particle ratios, ${}^3$He/d and ${}^3$He/p, in Pb-Pb collisions are found to be in agreement with a common chemical freeze-out temperature of $T_{\mathrm{chem}}\approx 156$ MeV. These ratios do not vary with centrality which is in agreement with the thermal-statistical model. In a coalescence approach, it excludes models in which nucleus production is proportional to the particle multiplicity and favors those in which it is proportional to the particle density instead. In addition, the observation of 31 anti-tritons in Pb-Pb collisions is reported. For comparison, the deuteron spectrum in pp collisions at $\sqrt{s}=7$ TeV is also presented. While the p/$\pi$ ratio is similar in pp and Pb-Pb collisions, the d/p ratio in pp collisions is found to be lower by a factor of 2.2 than in Pb-Pb collisions.

   nucl-exPRC(2016)·332 citations
4. 04*

   Measurement of the branching ratio for beta-delayed alpha decay of 16N

   J. Refsgaard · O.S. Kirsebom🇩🇰 · E.A. Dijck🇳🇱 · H.O.U. Fynbo🇩🇰 · M.V. Lund🇩🇰 · M.N. Portela · R. Raabe🇧🇪 · G. Randisi🇫🇷 · F. Renzi🇮🇹 · S. Sambi · A. Sytema🇳🇱 · L. Willmann🇳🇱 · H.W. Wilschut🇳🇱

   While the 12C(a,g)16O reaction plays a central role in nuclear astrophysics, the cross section at energies relevant to hydrostatic helium burning is too small to be directly measured in the laboratory. The beta-delayed alpha spectrum of 16N can be used to constrain the extrapolation of the E1 component of the S-factor; however, with this approach the resulting S-factor becomes strongly correlated with the assumed beta-alpha branching ratio. We have remeasured the beta-alpha branching ratio by implanting 16N ions in a segmented Si detector and counting the number of beta-alpha decays relative to the number of implantations. Our result, 1.49(5)e-5, represents a 24% increase compared to the accepted value and implies an increase of 14% in the extrapolated S-factor.

   nucl-exPLB(2016)·12 citations
5. 05*

   Measurement of pi^0 photoproduction on the proton at MAMI C

   P. Adlarson🇩🇪 · F. Afzal🇩🇪 · C. S. Akondi🇺🇸 · J. R. M. Annand🇬🇧 · H. J. Arends🇩🇪 · Ya. I. Azimov🇷🇺 · R. Beck🇩🇪 · N. Borisov🇷🇺 · A. Braghieri🇮🇹 · W. J. Briscoe🇺🇸 · S. Cherepnya🇷🇺 · F. Cividini🇩🇪 and 79 other authors

   Differential cross sections for the gamma p -> pi^0 p reaction have been measured with the A2 tagged-photon facilities at the Mainz Microtron, MAMI C, up to the center-of-mass energy W=1.9 GeV. The new results, obtained with a fine energy and angular binning, increase the existing quantity of pi^0 photoproduction data by ~47%. Owing to the unprecedented statistical accuracy and the full angular coverage, the results are sensitive to high partial-wave amplitudes. This is demonstrated by the decomposition of the differential cross sections in terms of Legendre polynomials and by further comparison to model predictions. A new solution of the SAID partial-wave analysis obtained after adding the new data into the fit is presented.

   ↳ hep-exnucl-exPRC(2015)·65 citations
6. 06*

   XMASS: Recent results and status

   Katsuki Hiraide (for the XMASS Collaboration)🇯🇵

   The XMASS project is designed for multiple physics goals using highly-purified liquid xenon scintillator in an ultra-low radioactivity environment. As the first stage of the project, the detector with 835 kg of liquid xenon was constructed and is being operated. In this paper, we present results from our commissioning data, current status of the experiment, and a next step of the project.

   ↳ physics.ins-detastro-ph.COastro-ph.IMhep-ex+18 citations
7. 07*

   Systematic study of the experimental measurements on $J/\psi$ cross section and kinematic distribution in $p+p$ collisions at different energies

   Wangmei Zha🇨🇳 · Bingchu Huang🇺🇸 · Rongrong Ma🇺🇸 · Lijuan Ruan🇺🇸 · Zebo Tang🇨🇳 · Zhangbu Xu🇺🇸 · Chi Yang🇨🇳 · Qian Yang🇨🇳 · Shuai Yang🇨🇳

   The world experimental data on cross section and kinematic distribution in $p+p$ and $p+A$ collisions at $\sqrt{s}$ = 6.8 - 7000 GeV are examined in systematic way. The $\sqrt{s}$ dependence of the inclusive cross section, rapidity and transverse momentum distributions are studied phenomenologically. We explore empirical formulas to obtain the total cross section, rapidity and transverse momentum ($p_T$) distribution. This is crucial for the interpretation of A$+$A $J/\psi$ results at RHIC when the $p+p$ reference data are not available. In addition, the cross section at mid-rapidity and transverse momentum distributions in $p+p$ collisions at $\sqrt{s}$ = 39 and 62.4 GeV are evaluated.

   ↳ hep-exnucl-exPRC(2016)·22 citations
8. 08*

   Symmetry energy systematics and its high density behavior

   Lie-Wen Chen🇨🇳

   We explore the systematics of the density dependence of nuclear matter symmetry energy in the ambit of microscopic calculations with various energy density functionals, and find that the symmetry energy from subsaturation density to supra-saturation density can be well determined by three characteristic parameters of the symmetry energy at saturation density ${\rho }_0$, i.e., the magnitude $E_{\text{sym}}({\rho }_0)$, the density slope $L$ and the density curvature $K_{\text{sym}}$. This finding opens a new window to constrain the supra-saturation density behavior of the symmetry energy from its (sub-)saturation density behavior. In particular, we obtain $L=46.7\pm 12.8$ MeV and $K_{\text{sym}}=-166.9\pm 168.3$ MeV as well as $E_{\text{sym}}(2{\rho }_0)\approx 40.2\pm 12.8$ MeV and $L(2{\rho }_0)\approx 8.9\pm 108.7$ MeV based on the present knowledge of $E_{\text{sym}}({\rho }_0)=32.5\pm 0.5$ MeV, $E_{\text{sym}}({\rho }_c)=26.65\pm 0.2$ MeV and $L({\rho }_c)=46.0\pm 4.5$ MeV at ${\rho }_{\mathrm{c}}=0.11$ fm${}^{-3}$ extracted from nuclear mass and the neutron skin thickness of Sn isotopes. Our results indicate that the symmetry energy cannot be stiffer than a linear density dependence.In addition, we also discuss the quark matter symmetry energy since the deconfined quarks could be the right degree of freedom in dense matter at high baryon densities.

   ↳ nucl-thastro-ph.HEastro-ph.SRnucl-exEPJ Web Conf.(2015)·32 citations
9. 09*

   Multihadron production dynamics exploring the energy balance in hadronic and nuclear collisions

   Edward K.G. Sarkisyan🇨🇭 · Aditya Nath Mishra🇮🇳 · Raghunath Sahoo🇮🇳 · Alexander S. Sakharov🇨🇭

   The multihadron production in nucleus-nucleus collisions and its interrelation with that in (anti)proton-proton interactions are studied by exploring the charged particle mean multiplicity collision-energy and centrality dependencies in the measurements to date. The study is performed in the framework of the recently proposed effective-energy approach which, under the proper scaling of the collision energy, combines the constituent quark picture with Landau relativistic hydrodynamics counting for the centrality-defined effective energy of participants and relating different types of collisions. Within this approach, the multiplicity energy dependence and the pseudorapidity spectra from the most central nuclear collisions are well reproduced. The study of the multiplicity centrality dependence reveals a new scaling between the measured pseudorapidity spectra and the calculations. By means of this scaling, called the energy balanced limiting fragmentation scaling, one reproduces the pseudorapidity spectra for all centralities. The scaling elucidates some differences in the multiplicity and midrapidity density centrality dependence obtained at RHIC and LHC. These findings reveal an inherent similarity in the multiplicity energy dependence from the most central collisions and centrality data. A new regime in heavy-ion collisions to occur at about a TeV energy is indicated, similar to that observed in the earlier studies of the midrapidity densities. Predictions are made for the mean multiplicities to be measured in proton-proton and heavy-ion collisions at the LHC.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2016)·71 citations
10. 10*

    Application of Real-time Digitization Technique in Beam Measurement for Accelerators

    Lei Zhao🇨🇳 · Linsong Zhan🇨🇳 · Xingshun Gao · Shubin Liu🇨🇳 · Qi An🇨🇳

    Beam measurement is very important for accelerators. With the development of analog-to-digital conversion techniques, digital beam measurement becomes a research hot spot. IQ (In-phase & Quadrature-phase) analysis based method is an important beam measurement approach, the principle of which is presented and discussed in this paper. The State Key Laboratory of Particle Detection and Electronics in University of Science and Technology of China has devoted efforts to the research of digital beam measurement based on high-speed high-resolution analog-to-digital conversion, and a series of beam measurement instruments were designed for China Spallation Neutron Source (CSNS), Shanghai Synchrotron Radiation Facility (SSRF), and Accelerator Driven Sub-critical system (ADS).

    ↳ physics.acc-phnucl-exCPC(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.