17011670
Color-octet contributions to J/ psi hadroproduction at fixed target energies.
We investigate the integrated cross section for forward {ital J}/{psi} production in proton-proton and pion-proton collisions at center-of-mass energies up to 60 GeV. We find that color-octet contributions to the cross section are crucially important, and their inclusion produces a very good description of the data. Since the values of nonperturbative matrix elements are fixed by other experiments, these predictions are parameter-free. {copyright} {ital 1996 The American Physical Society.}
122166973
The phase diagram of QCD: methods and logic of the comparison of experiments and theory
Abstract A small review of the phase diagram of QCD is presented. This is followed by a discussion of the conditions under which experimental data on the fluctuations of conserved quantities in heavy-ion collisions can be treated in the grand canonical ensemble. A robust method for detecting the presence of a nearby critical point in experiments is given. There is a short discussion of the need for non-Gaussian error analysis.
121387686
Hybrid Monte Carlo simulations of a two-dimensional gauge theory
Through a study of the dynamics of the two-dimensional U(1) pure gauge theory we find exponential slowing down in barrier penetration problems. We verify that the dynamical critical exponent in HMC can be tuned exactly to 1, and that normal and gauge fixed updates have equal cost.
123004962
Flavour degrees of freedom and the transition temperature in QCD
We study the finite temperature transition in QCD with four flavours of dynamical quarks. Our simulation is performed on an 8×16 3 lattice for quarks of mass ma=0.01. At the coupling β c =5.15, we find long-lived metastable states, as well as an abrupt change in the entropy density, suggesting a first order phase transition. Using presently available results from corresponding calculations of the hadron masses and the chiral condensate, this gives us a transition temperature T c ≅100 MeV, which is a factor two lower than the transition temperature found in quenched QCD.
17443615
Lattice QCD for RHIC
I briefly introduce the methods by which lattice QCD predictions for RHIC are obtained. Next I deal with lattice determinations of strangeness production and event-to-event fluctuations of conserved quantities. I also present a new diagrammatic method for computing derivatives with respect to chemical potentials, and conclude with discussions of some tests of thermal perturbation theory which follow.
119431013
A precise determination of T_c in QCD from scaling
Existing lattice data on the QCD phase transition are analyzed in renormalized perturbation theory. In quenched QCD it is found that T_c scales for lattices with only 3 time slices, and that T_c/Lambda_msbar=1.15 \pm 0.05. A preliminary estimate in QCD with two flavours of dynamical quarks shows that this ratio depends on the quark mass. For realistic quark masses we estimate T_c/Lambda_msbar=0.49 \pm 0.02. We also investigate the equation of state in quenched QCD at 1-loop order in renormalised perturbation theory.
1626866
Gauge-boson scattering signals at the CERN LHC.
We have extended our earlier treatment of the gauge-boson scattering with radiative corrections in the standard model at supercollider energies, and computed the rates for gauge-boson scattering modes in {ital pp} collisions leading to the final states {ital W}{sup +}{ital W}{sup {minus}}, {ital ZZ}(4{ital l}), {ital ZZ}(2{ital l}2{nu}), {ital W}{sup {plus_minus}}{ital Z}, and {ital W}{sup {plus_minus}}{ital W}{sup {plus_minus}}. Our results at the CERN LHC energy of {radical}{ital s}=14 TeV for {ital m}{sub {ital H}}=1000 GeV are compared with those recently obtained by Bagger {ital et} {ital al}. These results will be useful in the search for the Higgs bosons at supercollider energies as well as for experimentally distinguishing the standard model from nonminimal Higgs models. {copyright} {ital 1996 The American Physical Society.}
31179622
Elastic scattering of alpha particles from 209Bi at 24.8, 28.5, 34.7, 38.8, and 69.5 MeV.
Differential cross sections for the elastic scattering of alpha particles from {sup 209}Bi have been measured over a wide angular range at a number of energies between 24 and 70 MeV. The present data along with existing data in this energy range have been analyzed using the optical model with both phenomenological and double-folded potentials. The application of the dispersion relation of Mahaux, Ng{cflx o}, and Satchler allows a reproduction of the observed energy dependence of the real part of the potential. A nearside-farside decomposition of the data clearly reveals large-angle Fraunhoefer oscillations. The inelastic cross sections at 69.5 MeV have also been measured and the deformation lengths obtained from a distorted-wave Born analysis are consistent with values reported in the literature.
39485818
Nucleus-nucleus potential from fusion and elastic scattering.
An analytical expression for the calculation of the nucleus-nucleus potential has been derived from an empirical formula which describes the fusion excitation function. The nucleus-nucleus potentials calculated for the projectiles /sup 6/Li, /sup 9/Be, and /sup 12/C in the interaction region --3--6.5 fm by the above procedure agree remarkably well with the real part of the respective optical potentials determined from the analysis of elastic scattering data which exhibit the ''rainbow'' phenomenon.
10011120
Bc spectroscopy in a quantum-chromodynamic potential model.
We have investigated {ital B}{sub {ital c}} spectroscopy with the use of a quantum-chromodynamic potential model which was recently used by us for the light-heavy quarkonia. We give our predictions for the energy levels and the {ital E}1 transition widths. We also find, rather surprisingly, that although {ital B}{sub {ital c}} is not a light-heavy system, the heavy quark effective theory with the inclusion of the {ital m}{sub {ital b}}{sup -}{sup 1} and {ital m}{sub {ital b}}{sup -}{sup 1}ln{ital m}{sub {ital b}} corrections is as successful for {ital B}{sub {ital c}} as it is for {ital B} and {ital B}{sub {ital s}}. {copyright} {ital 1995 The American Physical Society.}
12293063
Detection of ultrahigh-energy radiation from Scorpius X-1: Ooty observations during 1984-1987.
A detailed study of showers arriving from the direction of Scorpius X-1 has shown strong evidence for emission of ultrahigh-energy radiation from Scorpius X-1 during the period 4 March-2 May 1986. 178 showers were observed in the source bin againat an expected background of 122.9. The chance probability for observing this excess has been estimated from simulations to be less than 10 -3 . The flux observed during this period was (6.4±1.6)×10 -12 cm -2 s -1 at energies >2.5×10 14 eV, corresponding to a luminosity of 2×10 35 ergs s -1 .