Hadron spectrum in QCD with valence Wilson fermions and dynamical staggered fermions at 6/g2=5.6.
We present an analysis of hadronic spectroscopy for Wilson valence quarks with dynamical staggered fermions at a lattice coupling 6/{ital g}{sup 2}={beta}=5.6 at a sea-quark mass of {ital am}{sub {ital q}}=0.01 and 0.025, and of Wilson valence quarks in the quenched approximation at {beta}=5.85 and 5.95, both on 16{sup 3}{times}32 lattices. We make comparisons with our previous results with dynamical staggered fermions at the same parameter values but on 16{sup 4} lattices doubled in the temporal direction.

title: Biased Metropolis-heat-bath algorithm for fundamental-adjoint SU(2) lattice gauge theory
abstract: For SU(2) lattice gauge theory with the fundamental-adjoint action an efficient heat-bath algorithm is not known so that one had to rely on Metropolis simulations supplemented by overrelaxation. Implementing a novel biased Metropolis-heat-bath algorithm for this model, we find improvement factors in the range 1.45 to 2.06 over conventionally optimized Metropolis simulations. If one optimizes further with respect to additional overrelaxation sweeps, the improvement factors are found in the range 1.3 to 1.8.

title: Infrared and ultraviolet properties of the Landau gauge quark propagator
abstract: We present a current summary of a program to study the quark propagator using lattice QCD. We use the Overlap and “Asqtad” quark actions on a number of lattice ensembles. to assess systematic errors. We comment on the place of this work amongst studies of QCD Green's functions in other formulations. A preliminary calculation of the running quark mass is presented.

title: Divergent chiral condensate in the quenched Schwinger model
abstract: We calculate numerically the eigenvalue distribution of the overlap Dirac operator in the quenched Schwinger model on a lattice. The distribution does not fit any of the three universality classes of spontaneous chiral-symmetry breaking, and its strong volume dependence indicates that the chiral condensate in the quenched theory is an ill-defined and divergent quantity. When we reweight configurations with the Dirac determinant to study the theory with N{sub f}=1, we obtain a distribution of eigenvalues that is well-behaved and consistent with the theory of explicit symmetry breaking due to the anomaly.

title: Search for symmetry restoration in the fundamental SU(2) Higgs model
abstract: The phase structure of the fundamental SU(2) Higgs model at finite temperature is investigated close to the zero-temperature Higgs transition by Monte Carlo methods. In the confined phase at zero temperature we find a crossover from a confined to a deconfined region that remains quite sharp on lattices of temporal extent NT = 4 even close to the Higgs transition. On asymmetric lattices the Higgs transition shifts slightly compared to the zero-temperature, symmetric lattice, giving indirect evidence for symmetry restoration at high temperature.

title: Study of chiral symmetry in quenched QCD using the overlap Dirac operator
abstract: We compute fermionic observables relevant to the study of chiral symmetry in quenched QCD using the overlap Dirac operator for a wide range of fermion mass. We use analytical results to disentangle the contribution from exact zero modes and simplify our numerical computations. Details concerning the numerical implementation of the overlap Dirac operator are presented.

title: Comparison of 20 exclusive reactions at large t.
abstract: We report a study of 20 exclusive reactions measured at the AGS at 5.9 GeV/[ital c] incident momentum, 90[degree] center of mass. This experiment confirms the strong quark flow dependence of two-body hadron-hadron scattering at large angle. At 9.9 GeV/[ital c] an upper limit had been set for the ratio of cross sections for ([ital [bar p]p][r arrow][ital [bar p]p])/([ital pp][r arrow][ital pp]) at 90[degree] c.m. with the ratio less than 4%. The present experiment was performed at lower energy to gain sensitivity, but was still within the fixed angle scaling region. A ratio [ital R]([ital [bar p]p]/[ital pp])[approx]1/40 was measured at 5.9 GeV/[ital c], 90[degree] c.m. in comparison to a ratio near 1.7 for small angle scattering. In addition, many other reactions were measured, often for the first time at 90[degree] c.m. in the scaling region, using beams of [pi][sup [plus minus]], [ital K][sup [plus minus]], [ital p] and [ital [bar p]] on a hydrogen target. There are similar large differences in cross sections for other reactions: [ital R]([ital K][sup [minus]][ital p][r arrow][pi][sup +][Sigma][sup [minus]]/[ital K][sup [minus]][ital p][r arrow][pi][sup [minus]][Sigma][sup +])[approx]1/12, for example. The relative magnitudes of the different cross sections are consistent with the dominance of quark interchangemore » in these 90[degree] reactions, and indicate that pure gluon exchange and quark-antiquark annihilation diagrams are much less important. The angular dependence of several elastic cross sections and the energy dependence at a fixed angle of many of the reactions are also presented.« less

title: Comparison of exclusive reactions at large t.
abstract: Cross sections or upper limits are reported for 12 meson-baryon and two baryon-baryon reactions for an incident momentum of 9.9 GeVc, near 90/sup 0/ c.m.: ..pi../sup +- /p..-->..p..pi../sup +- /,pp/sup +- /,..pi../sup +0//sup +- /,K/sup +/)Sigma)/sup +- /, (..lambda../sup 0/)Sigma)/sup 0/)K/sup 0/;K/sup +- /p..-->..pK/sup +- /;p/sup +- /p..-->..pp. By studying the flavor dependence of the different reactions, we have been able to isolate the quark-interchange mechanism as dominant over gluon exchange and quark-antiquark annihilation

title: Measurements of production polarization and decay asymmetry for Xi - hyperons.

title: Evolution of the density parameter in multidimensional cosmology.
abstract: Inflation as a dynamical effect of extra dimensions is discussed from the viewpoint of the evolution of the parameters Ω and q in the physical space. By reducing the dynamics of the models FLRW (k=±1)×T D (T D =S 1 ×... ×S 1 ) and FLRW (k=0)×S D , where FLRW denotes Friedmann, Lemaitre, Robertson, and Walker, to two dimensions it is shown that inflation need not imply Ω≃ 1 for the present time, i.e., that it does not solve the flatness problem. The energy-momentum tensor of the form T υ μ =(ρ,mρ,mρ,mρ,nρ,..., nρ) is assumed

title: Evidence for time and directional enhancements of multimuon cosmic-ray events.
abstract: We have observed 1.05 x 10/sup 6/ single-muon and 6869 multimuon events deep underground with the Soudan 1 nucleon-decay detector. The single-muon flux is consistent with isotropy and with results of previous experiments. We have found indications of bursts of multimuon events, particularly from a direction near Cygnus X-3. These bursts arrive from an extended angular region of 30/sup 0/ x 30/sup 0/. The size of the angular region and the lack of a corresponding effect in the single-muon events are difficult to understand. In addition, there is weaker evidence for an excess in the time-integrated multimuon flux near the north galactic pole. We have evaluated the possibility that these effects are caused by random or systematic errors.