121663425
Quantum-chromodynamic potential model for light and heavy quarkonia
Our earlier treatment for the investigation of the cc-bar, bb-bar, and tt-bar spectra is extended to other p quarkonia with u, d, s, c, and b quarks. We find that it is possible to account fully for the observed ground-state hyperfine splittings of light as well as heavy quarkonia provided that the perturbative quantum-chromodynamic potential is supplemented not only by the nonperturbative confining potential but also by a nonperturbative annihilation potential which rapidly decreases with increase in the quark mass. We also give our predictions for the experimentally interesting bu-bar, bs-bar, and bc-bar systems with unknown mass splittings.
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.}
1943581
Quark confinement in quantum chromodynamics.
A quark-confinement mechanism inspired by renormalization-group-improved perturbative quantum chromodynamics is proposed. We obtain a quark-antiquark confining potential in the lowest approximation, show that it yields reasonable results for the bb-bar and cc-bar spin-averaged energy levels, and comment on the significance of the higher-order effects.
625025
Relativistic two-photon and two-gluon decay rates of heavy quarkonia.
The decay rates of {ital c{bar c}} and {ital b{bar b}} through two-photon or two-gluon annihilations are obtained by using totally relativistic decay amplitudes and a sophisticated quantum-chromodynamic potential model for heavy quarkonia. Our results for the photonic and gluonic widths of the {sup 1}{ital S}{sub 0}, {sup 3}{ital P}{sub 0}, and the {sup 3}{ital P}{sub 2} states are in excellent agreement with the available experimental data. The procedures and mathematical techniques used by us for the treatment of the fermion-antifermion bound states are also applicable to other decay processes. {copyright} {ital 1996 The American Physical Society.}
6552264
Nonsingular potential model for heavy quarkonia.
A nonsingular potential model for heavy quarkonia is described which does not require recourse to an illegitimate perturbative treatment for the investigation of quarkonium spectra. Our overall results for the energy levels, the leptonic widths, and the E1 transition widths are in very good agreement with the experimental data for bb-bar and they are reasonably good for cc-bar. We also find that the confining part of the quarkonium potential is scalar-vector exchange rather than the currently favored scalar exchange.
17051703
Quantum-chromodynamic potential model for light-heavy quarkonia and the heavy quark effective theory.
We have investigated the spectra of light-heavy quarkonia with the use of a quantum-chromodynamic potential model, which is similar to that used earlier for heavy quarkonia. An essential feature of our treatment is the inclusion of the one-loop radiative corrections to the quark-antiquark potential, which contribute significantly to the spin splitting among the quarkonium energy levels. Unlike [ital c[bar c]] and [ital b[bar b]], the potential for a light-heavy system has a complicated dependence on the light and heavy quark masses [ital m] and [ital M], and it contains a spin-orbit mixing term. We have obtained excellent results for the observed energy levels of [ital D][sup 0], [ital D][sub [ital s]], [ital B][sup 0], and [ital B][sub [ital s]], and we are able to provide predicted results for many unobserved energy levels. Our potential parameters for different quarkonia satisfy the constraints of quantum chromodynamics. We have also used our investigation to test the accuracy of the heavy quark effective theory. We find that the heavy quark expansion yields generally good results for the [ital B][sup 0] and [ital B][sub [ital s]] energy levels provided that [ital M][sup [minus]1] and [ital M][sup [minus]1] ln [ital M] corrections are taken into account more » in the quark-antiquark interactions. It does not, however, provide equally good results for the energy levels of [ital D][sup 0] and [ital D][sub [ital s]], which indicates that the effective theory cannot be applied accurately to the [ital c] quark. « less
118984972
Calculations for populations of selected isotopes in intermediate-energy heavy ion collisions
We compute the populations of isotopes of Boron, Carbon and Nitrogen measured experimentally in intermediate energy heavy ion collisions. A two component soluble statistical model is used to find the initial populations of different nuclei at a finite temperature. These initial populations are both in particle stable and particle unstable states. The particle unstable states then decay. The final populations after these decays are computed and compared with experimental data.
16308546
First Order Phase Transition in Intermediate-Energy Heavy Ion Collisions
We model the disassembly of an excited nuclear system formed as a result of a heavy ion collision. We find that, as the beam energy in central collisions in varied, the dissociating system crosses a liquid-gas coexistence curve, resulting in a first-order phase transition. Accessible experimental signatures are identified: a peak in specific heat, a power-law yield for composites, and a maximum in the second moment of the yield distribution.
117567170
The average mass number of primary cosmic rays around the knee region derived from Grapes III array at Ooty
We analyzed three months data on air showers (total 10 showers in 10<Ne<10) observed with the GRAPES III experiment during 2001. The shower array consists of 257 scintillation detectors (1m each) and 16 muon detectors (35 m each). Very large area (560m) of the muon detectors gives good statistics for estimating the number of muons even for small air showers. We present the correlation between muon multiplicity distribution and shower size. This result is compared with simulation (Corsika code with QGS Jet model) for primary energy between 10 eV and 10 eV. We find the average mass number in this energy region follows gradual increase and mixing of proton and heavy nuclei model fits well our observed data.
115460487
Compositional variation of Fe-group nuclei in cosmic rays due to K-capture effect.
124737204
Thermalization of quarkonia at energies available at the CERN Large Hadron Collider
We argue that the relative yields of $\Upsilon$ states observed at the LHC can be understood as bottomonium states coming to early thermal equilibrium and then freezing out. The bottomonium freezeout temperature is approximately 250 MeV. We examine its systematics as a function of centrality. We remark on the interesting differences seen by the CMS and ALICE experiments in the charmonium sector.