Transverse energy per charged particle at relativistic energies from a statistical model with expansion

Transverse energy and charged particle pseudorapidity densities at midrapidity and their ratio, $dE_{T}/d\eta\mid_{mid} / dN_{ch}/d\eta|_{mid}$, are evaluated in a statistical model with longitudinal and transverse flows for the wide range of colliders, from AGS to RHIC at $\sqrt{s_{NN}}=200$ GeV. Evaluations are done at freeze-out parameters established independently from fits to observed particle yields and $p_{T}$ spectra. Decays of hadron resonances are treated thoroughly and are included in derivations of $dE_{T}/d\eta|_{mid}$ and $dN_{ch}/d\eta|_{mid}$. The predictions of the model agree well with the experimental data. However, some (explicable) overestimation of the ratio has been observed.Comment: Revtex, 11 pages, 1 figure (included), The revised version with the title changed and new conclusions added, to appear in Eur. Phys. J.

Charge Particle Multiplicity and Transverse Energy Measurements in Au-Au collisions in PHENIX at RHIC

We present results on charged particle and transverse energy densities measured at mid-rapidity in Au-Au collisions at sqrt(s_{NN})=200 GeV. The mean transverse energy per charged particle is derived. The results are presented as a function of centrality, which is defined by the number of participating nucleons, and compared to results obtained in Au-Au collisions at sqrt{s_{NN})=130 GeV. A comparison with calculations from various theoretical models is performed.Comment: 4 pages, 5 figures. Talk presented at Quark Matter 2002, Nantes, France, July 18-24, 2002. To appear in the proceedings (Nucl. Phys. A

From the ISR to RHIC--measurements of hard-scattering and jets using inclusive single particle production and 2-particle correlations

Hard scattering in p-p collisions, discovered at the CERN ISR in 1972 by the method of leading particles, proved that the partons of Deeply Inelastic Scattering strongly interacted with each other. Further ISR measurements utilizing inclusive single or pairs of hadrons established that high pT particles are produced from states with two roughly back-to-back jets which are the result of scattering of constituents of the nucleons as desribed by Quantum Chromodynamics (QCD), which was developed during the course of these measurements. These techniques, which are the only practical method to study hard-scattering and jet phenomena in Au+Au central collisions at RHIC energies, are reviewed, as an introduction to present RHIC measurements.Comment: To appear in the proceedings of the workshop on Correlations and Fluctuations in Relativistic Nuclear Collisions, MIT, Cambridge, MA, April 21-23, 2005, 10 pages, 9 figures, Journal of Physics: Conference Proceeding

Effect of 3D Polarization profiles on polarization measurements and colliding beam experiments

N/

Dependence of hadron spectra on decoupling temperature and resonance contributions

Using equilibrium hydrodynamics with initial conditions for the energy and net baryon number densities from the perturbative QCD + saturation model, a good simultaneous description of the measured pion, kaon and (anti)proton spectra in central Au+Au collisions at $\sqrt s=130 A$GeV is found with a single decoupling temperature \Tdec=150...160 MeV. The interplay between the resonance content of the EoS and the development of the transverse flow leads to inverse slopes and $$ of hadrons which increase with decreasing \Tdec. The origin of this result is discussed.Comment: 4 pages, 2 eps-figures. Section 3 rewritten, table 1 and figure 1 redrawn, 2 references adde

Исследование новых критериев для обнаружения автокорреляции остатков первого порядка в регрессионных моделях

When estimating regression models using the least squares method, one of its prerequisites is the lack of autocorrelation in the regression residuals. The presence of autocorrelation in the residuals makes the least-squares regression estimates to be ineffective, and the standard errors of these estimates to be untenable. Quantitatively, autocorrelation in the residuals of the regression model has traditionally been estimated using the Durbin-Watson statistic, which is the ratio of the sum of the squares of differences of consecutive residual values to the sum of squares of the residuals. Unfortunately, such an analytical form of the Durbin-Watson statistic does not allow it to be integrated, as linear constraints, into the problem of selecting informative regressors, which is, in fact, a mathematical programming problem in the regression model. The task of selecting informative regressors is to extract from the given number of possible regressors a given number of variables based on a certain quality criterion.The aim of the paper is to develop and study new criteria for detecting first-order autocorrelation in the residuals in regression models that can later be integrated into the problem of selecting informative regressors in the form of linear constraints. To do this, the paper proposes modular autocorrelation statistic for which, using the Gretl package, the ranges of their possible values and limit values were first determined experimentally, depending on the value of the selective coefficient of auto-regression. Then the results obtained were proved by model experiments using the Monte Carlo method. The disadvantage of the proposed modular statistic of adequacy is that their dependencies on the selective coefficient of auto-regression are not even functions. For this, double modular autocorrelation criteria are proposed, which, using special methods, can be used as linear constraints in mathematical programming problems to select informative regressors in regression models.При оценивании регрессионных моделей с помощью метода наименьших квадратов, одной из его предпосылок является отсутствие автокорреляции в остатках регрессии. Наличие автокорреляции остатков делает оценки регрессии, полученные методом наименьших квадратов, неэффективными, а стандартные ошибки этих оценок – несостоятельными. Количественно автокорреляцию в остатках регрессионной модели традиционно принято оценивать с помощью критерия Дарбина–Уотсона, представляющего собой отношение суммы квадратов разностей последовательных значений остатков к сумме квадратов остатков. К сожалению, такой аналитический вид критерия Дарбина – Уотсона не позволяет интегрировать его в виде линейных ограничений в задачу отбора информативных регрессоров, являющуюся, по сути, задачей математического программирования, в регрессионной модели. Задача отбора информативных регрессоров заключается в выделении из заданного числа возможных регрессоров заданного числа переменных на основе некоторого критерия качества. Целью данной работы является разработка и исследование новых критериев для обнаружения автокорреляции остатков первого порядка в регрессионных моделях, которые в дальнейшем могут быть интегрированы в задачу отбора информативных регрессоров в виде линейных ограничений. Для этого в статье предложены модульные критерии автокорреляции, для которых с использованием пакета Gretl сначала экспериментально были определены диапазоны их возможных значений и предельные значения в зависимости от значения выборочного коэффициента авторегрессии. Затем полученные результаты были подтверждены с помощью модельных экспериментов по методу Монте-Карло. Недостатком предложенных модульных критериев адекватности является то, что их зависимости от выборочного коэффициента авторегрессии не являются четными функциями. Для этого предлагаются двойные модульные критерии автокорреляции, которые с помощью специальных приёмов могут быть использованы в виде линейных ограничений в задачах математического программирования для отбора информативных регрессоров в регрессионных моделях

Proceedings of RIKEN BNL Research Center Workshop: Progress in High-pT Physics at RHIC

This volume archives the presentations at the RIKEN BNL Research Center workshop 'Progress in High-PT Physics at RHIC', held at BNL in March 2010. Much has been learned from high-p{sub T} physics after 10 years of RHIC operations for heavy-ion collisions, polarized proton collisions and d+Au collisions. The workshop focused on recent progress in these areas by both theory and experiment. The first morning saw review talks on the theory of RHIC high-p{sub T} physics by G. Sterman and J. Soffer, and on the experimental results by M. Tannenbaum. One of the most exciting recent results from the RHIC spin program is the first observation of W bosons and their associated single-spin asymmetry. The new preliminary data were reported on the first day of our workshop, along with a theoretical perspective. There also were detailed discussions on the global analysis of polarized parton distributions, including the knowledge on gluon polarization and the impact of the W-data. The main topic of the second workshop day were single-transverse spin asymmetries and their analysis in terms of transverse-momentum dependent parton distributions. There is currently much interest in a future Drell-Yan program at RHIC, thanks to the exciting physics opportunities this would offer. This was addressed in some of the talks. There also were presentations on the latest results on transverse-spin physics from HERMES and BELLE. On the final day of the workshop, the focus shifted toward forward and small-x physics at RHIC, which has become a cornerstone of the whole RHIC program. Exciting new data were presented and discussed in terms of their possible implications for our understanding of strong color-field phenomena in QCD. In the afternoon, there were discussions of nuclear parton distributions and jet observables, among them fragmentation. The workshop was concluded with outlooks toward the near-term (LHC, JLab) and longer-term (EIC) future. The workshop has been a great success. We had excellent presentations throughout and productive discussions, which showed the importance and unique value of the RHIC high-p{sub T} program. We are grateful to all participants for coming to BNL. The support provided by the RIKEN-BNL Research Center for this workshop has been magnificent, and we are most grateful for it. We also thank Brookhaven National Laboratory and the U.S. Department of Energy for providing additional support and for the facilities to hold this workshop. Finally, sincere thanks go to Pamela Esposito for her most efficient and tireless work in organizing and running the workshop