A new measurement of J/psi suppression in Pb-Pb collisions at 158 GeV per nucleon

We present a new measurement of J/psi production in Pb-Pb collisions at 158 GeV/nucleon, from the data sample collected in year 2000 by the NA50 Collaboration, under improved experimental conditions with respect to previous years. With the target system placed in vacuum, the setup was better adapted to study, in particular, the most peripheral nuclear collisions with unprecedented accuracy. The analysis of this data sample shows that the (J/psi)/Drell-Yan cross-sections ratio measured in the most peripheral Pb-Pb interactions is in good agreement with the nuclear absorption pattern extrapolated from the studies of proton-nucleus collisions. Furthermore, this new measurement confirms our previous observation that the (J/psi)/Drell-Yan cross-sections ratio departs from the normal nuclear absorption pattern for semi-central Pb-Pb collisions and that this ratio persistently decreases up to the most central collisions.Comment: 19 pages, 10 figures. Submitted to Eur. Phys. J.

IgA nephropathy, the most common cause of glomerulonephritis, is linked to 6q22–23

19openopenAli G. Gharavi; Yan Yan; Francesco Scolari; F. Paolo Schena; Giovanni M. Frasca; Gian Marco Ghiggeri; Kerry Cooper; Antonio Amoroso; Battista Fabio Viola; Graziana Battini10; Gianluca Caridi8; Cristina Canova; Anita Farhi; Vairavan Subramanian; Carol Nelson-Williams; Sue Woodford; Bruce A. Julian; Robert J. Wyatt; Richard P. LiftonAli G., Gharavi; Yan, Yan; Scolari, Francesco; F., Paolo Schena; Giovanni M., Frasca; Gian Marco, Ghiggeri; Kerry, Cooper; Antonio, Amoroso; Battista Fabio, Viola; Graziana, Battini10; Gianluca, Caridi8; Cristina, Canova; Anita, Farhi; Vairavan, Subramanian; Carol Nelson, Williams; Sue, Woodford; Bruce A., Julian; Robert J., Wyatt; Richard P., Lifto

A comparative study of several bootstrap-based tests for the volatility in continuous-time diffusion models

This article develops three bootstrap-based tests for a parametric form of volatil- ity function in continuous-time diffusion models. The three tests are the generalized likelihood ratio test by Fan et al. (Ann Stat 29(1):153–193, 2001), the nonparamet- ric kernel test (LWZ) by Li and Wang (J Econometrics 87(1):145–165, 1998) and Zheng (J Econ 75(2):263–289, 1996) and the nonparametric test (CHS) by Chen et al. (2017). Monte Carlo simulations are performed to evaluate the sizes and power properties of these bootstrap-based tests in finite samples over a range of bandwidth values. We find that the bootstrap-based tests are not influenced by prior restrictions on the functional form of the drift function and that the bootstrap-based CHS test has better power performance than the bootstrap-based GLR and LWZ tests in detect- ing a parametric form of volatility. An empirical study on weekly treasury bill rate is further conducted to demonstrate these bootstrap-based test procedures.info:eu-repo/semantics/publishedVersio

Geometric Parameterization of J/ΨJ/\Psi Absorption in Heavy Ion Collisions

We calculate the survival probability of $J/\Psi$ particles in various colliding systems using a Glauber model. An analysis of recent data has reported a $J/\Psi$-nucleon breakup cross section of 6.2$\pm$0.7 mb derived from an exponential fit to the ratio of $J/\Psi$ to Drell-Yan yields as a function of a simple, linearly-averaged mean path length through the nuclear medium. Our calculations indicate that, due to the nature of the calculation, this approach yields an apparent breakup cross section which is systematically lower than the actual value.Comment: LaTex, 7 pages, 2 figure

Results on Charmonium States in Pb-Pb Interactions

We present cross-sections for J/$\psi$, $\psi^{\prime}$ and Drell-Yan production in lead-lead interactions at 158 GeV/nucleon. The Pb-Pb data, when compared with previous results obtained with lighter target or projectiles, show a similar behaviour for Drell-Yan, but exhibit an anomalous J/$\psi$ suppression, which increases with centrality

Statistical hadronization of charmed quarks at SPS and RHIC

Production of open and hidden charm hadrons in heavy ion collisions is considered within the statistical coalescence model. The charmed quark-antiquark pairs are assumed to be created at the initial stage of the reaction in hard parton collisions. The number of these pairs is conserved during the evolution of the system. At the hadronization stage, the charmed (anti)quarks are distributed among open and hidden charm hadrons in accordance with the laws of statistical mechanics. The model is in agreement with the experimental data on J/psi to Drell-Yan ratio in Pb+Pb collisions at SPS. This agreement can be reached only if a rather strong enhancement of the open charm production in central Pb+Pb collisions is assumed. A possible mechanism of the charm enhancement is discussed. At the top RHIC energy, the model predicts an increase of J/psi to Drell-Yan ratio in more central nucleus-nucleus collisions with respect to less central ones.Comment: Presented at 16th International Conference "Quark Matter", Nantes (France), July 18-24, 2002; 4 pages, LaTeX, 2 PS-figure

J/psi Production and Absorption in High Energy Proton-Nucleus Collisions

Measured J/Psi production cross sections for 200 and 450 GeV/c protons incident on a variety of nuclear targets are analyzed within a Glauber framework which takes into account energy loss of the beam proton, the time delay of particle production due to quantum coherence, and absorption of the J/Psi on nucleons. The best representation is obtained for a coherence time of 0.5 fm/c, previously determined by Drell-Yan production in proton-nucleus collisions, and an absorption cross section of 3.6 mb, which is consistent with the value deduced from photoproduction of the J/Psi on nuclear targets.Comment: LaTeX2e, 7 pages, 4 PS figures. Typos removed, minor change

Drell-Yan and J/psi Production in High Energy Proton-Nucleus and Nucleus-Nucleus Collisions

The distributions of outgoing protons and charged hadrons in high energy proton-nucleus collisions are described rather well by a linear extrapolation from proton-proton collisions. This linear extrapolation is applied to precisely measured Drell-Yan cross sections for 800 GeV protons incident on a variety of nuclear targets. The deviation from linear scaling in the atomic number A can be accounted for by energy degradation of the proton as it passes through the nucleus if account is taken of the time delay of particle production due to quantum coherence. We infer an average proper coherence time of 0.4 +/- 0.1 fm/c. Then we apply the linear extrapolation to measured J/psi production cross sections for 200 and 450 GeV/c protons incident on a variety of nuclear targets. Our analysis takes into account energy loss of the beam proton, the time delay of particle production due to quantum coherence, and absorption of the J/psi on nucleons. The best representation is obtained for a coherence time of 0.5 fm/c, which is consistent with Drell-Yan production, and an absorption cross section of 3.6 mb, which is consistent with the value deduced from photoproduction of the J/psi on nuclear targets. Finally, we compare to recent J/psi data from S+U and Pb+Pb collisions at the SPS. The former are reproduced reasonably well with no new parameters, but not the latter.Comment: Talks given at Quark Matter '99, the 14th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, Torino, Italy, May 10-14, 1999. 10 pages, five figure