121707912
A study of two-photon production of two-body final states with invariant mass greater than 2.0 GeV
Abstract We have measured the electron, muon, and charged-hadron pair production rates in two-phonon interactions for invariant masses above 2.0 GeV over a large of momentum transfer. The cross sections for electron and muon pairs show good agreement with the QED predictions at both small and large momentum transfer. The observed rate of hadron production is less than 6% of the rate that QED predicts for point-like hadrons, consistent with recent leading-order QCD calculations.
122313186
Search For Neutral Higgs Bosons From Supersymmetry In Z-decays
The light scalar Higgs boson h and the pseudoscalar Higgs boson A of the minimal supersymmetric standard model have been searched for in the processes e+e−→hff and e+e−→hA using data collected by ALEPH at the LEP e+e− collider, with center of mass energies at and near the Z peak. Using a variety of signatures adapted to various mass ranges for h and A, we have excluded a large domain in the parameter space. For large values of ν2ν1, the ratio of the vacuum expectation values of the two Higgs fields, the whole range from 0 to 38.8 GeV is excluded for Mh and MA at 95% CL.
124489366
Energy moments for quark jets at PETRA
Measurements of energy moments for single quark jets at c.m. energies between 12 and 31.6 GeV are presented. The data, corrected for detector effects and initial state radiation, are compared to QCD predictions in the leading log approximation. Non perturbative effects are found to be moderate, and they strongly decrease with increasing c.m. energy. Once partly corrected for the presence of these fragmentation effects, our data agree well with all features of the leading log prediction, and in particular with the variation of the strong coupling constant over a wide range of energies and momentum transfers.
121138073
BESII detector simulation
A Monte Carlo program based on GEANT3 has been developed for BESII detector simulation. The organization of the program is outlined, and the digitization procedure for simulating the response of various sub-detectors is described. Comparisons with data show that the performance of the program is generally satisfactory.
126182293
Evidence of psi(3770) nonD anti-D decay to J / psi pi+ pi-
104230837
tau mass measurement from e mu, e pi and (mu pi, mu mu, pi pi) channels at BES/BEPC
12226647
Mass relation between top and bottom quarks
Abstract In the framework of the recently proposed electroweak theory on a Planck lattice, we are able to solve approximately the lattice Dyson equation for the fermion self-energy functions, and obtain the ratio between the masses of the t - and b -quarks in terms of the electroweak coupling constants. The predicted top mass agrees with recent determinations from electroweak observables.
117893912
Pair‐production in inhomogeneous electric fields
This is a preliminary study on the rate of electron‐positron pair production in spatially inhomogeneous electric fields. We study the rate in the Sauter field and compare it to the rate in the homogeneous field.
125860973
The emergence of a heavy quark family on a lattice
Abstract Within the framework of the “Rome approach” for a lattice chiral gauge theory, the four-quark interaction with flavour symmetry is included. We analyse spontaneous symmetry breaking and compute composite modes and their contributions to the ground state energy. As a result, it is shown that the emergence of a heavy quark family is the energetically favoured solution.
17943046
On the physical processes which lie at the bases of time variability of GRBs
The relative-space-time-transformation (RSTT) paradigm and the interpretation of the burst-structure (IBS) paradigm are applied to probe the origin of the time variability of GRBs. Again GRB 991216 is used as a prototypical case, thanks to the precise data from the CGRO, RXTE and Chandra satellites. It is found that with the exception of the relatively inconspicuous but scientifically very important signal originating from the initial ``proper gamma ray burst'' (P-GRB), all the other spikes and time variabilities can be explained by the interaction of the accelerated-baryonic-matter pulse with inhomogeneities in the interstellar matter. This can be demonstrated by using the RSTT paradigm as well as the IBS paradigm, to trace a typical spike observed in arrival time back to the corresponding one in the laboratory time. Using these paradigms, the identification of the physical nature of the time variablity of the GRBs can be made most convincingly. It is made explicit the dependence of a) the intensities of the afterglow, b) the spikes amplitude and c) the actual time structure on the Lorentz gamma factor of the accelerated-baryonic-matter pulse. In principle it is possible to read off from the spike structure the detailed density contrast of the interstellar medium in the host galaxy, even at very high redshift.
42943773
On the Structures in the Afterglow Peak Emission of Gamma-Ray Bursts
Using GRB 991216 as a prototype, we show that the intensity substructures observed in what is generally called the "prompt emission" in gamma-ray bursts (GRBs) do originate in the collision between the accelerated baryonic matter pulse with inhomogeneities in the interstellar medium (ISM). The initial phase of such process occurs at a Lorentz factor γ ~ 310. The crossing of ISM inhomogeneities of sizes ΔR ~ 1015 cm occurs in a detector arrival time interval of ~0.4 s, implying an apparent superluminal behavior of ~105c. The long-lasting debate between the validity of the external shock model versus the internal shock model for GRBs is solved in favor of the first.