37501749
Search for direct CP violation in nonleptonic decays of charged Xi and lambda hyperons
A search for direct CP violation in the nonleptonic decays of hyperons has been performed. In comparing the product of the decay parameters, alpha(Xi)alpha(Lambda), in terms of an asymmetry parameter, A(XiLambda), between hyperons and antihyperons in the charged Xi-->Lambdapi and Lambda-->ppi decay sequence, we found no evidence of direct CP violation. The parameter A(XiLambda) was measured to be 0.012+/-0.014.
122693257
Inclusive Production of Lambda0 Hyperons by 300-GeV Protons: A-Dependence
Inclusive production of ${\ensuremath{\Lambda}}^{0}$ hyperons by 300-GeV protons has been measured at fixed production angles in the laboratory between 0 and 9 mrad and laboratory momenta from 65 to 300 GeV/c. Three different solid targets were used: beryllium, copper, and lead. The $A$ dependence of the data is suggestive of a collision model in which the hadron loses energy and gains transverse momentum as it leaves the nucleus. The experimental results are compared to such a model, and the implications are discussed.
120960559
New limit on magnetic monopole flux
The underground Soudan-1 nucleon decay experiment can measure the velocities of slowly moving particles if they can be detected by ionization at a level 0.5 times that of a relativistic muon. Magnetic monopoles predicted by grand unified theories should satisfy this condition if their velocities are greater than 10/sup -3/c. During a live time of 0.41 yr, no candidate has been observed, implying a 90%- confidence-level limit on the flux of such objects of <4.1 x 10/sup -13/ cm/sup -2/ sr/sup -1/ s/sup -1/ for velocities between 10/sup -3/c and 10/sup -2/c.
120389291
Study of quark flow in exclusive reactions at 90 degrees in the center of mass (AGS E838)
We report a study of quark flow in 20 exclusive reactions measured at Brookhaven National Laboratory’s AGS with a beam momentum of 5.9 GeV/c at 90° in the center of mass. This experiment confirms the strong quark flow reaction mechanism dependence of two‐body hadron scattering at large angles seen at 9.9 GeV/c. Large differences in cross sections for different reactions are consistent with the dominance of quark interchange in these 90° reactions, and indicate that pure gluon exchange and quark/antiquark annihilation diagrams are less important.
45066347
HARD QUARK-QUARK SCATTERING WITH EXCLUSIVE REACTIONS*
We have begun a program designed to study hard quark-quark scattering with exclusive reactions, focusing on quasi-elastic two-body reactions with all possible quark flavor exchanges. Examples are ..pi../sup -/p ..-->.. ..pi../sup -/p, rho/sup -/p, ..pi../sup +/..delta../sup -/, K/sup +/..sigma../sup -/, or K..lambda... Of the two-body exclusives, only elastic scattering had been measured at such large t previous to our experiment. By comparing the relative importance of different final states, the energy dependence of the production ratios of these states, the prominence of resonances such as rho/sup -/ over background in this region, and measuring polarizations where accessible, we have collected a large body of data on hard scattering in a completely new domain. Previously, essential all short distance QCD tests have been for inclusive processes. We have taken data with both negative and positive incident beam at 10 GeV/c on a hydrogen target and will present the first results, for ..pi../sup -/p ..-->.. ..pi../sup -/p and rho/sup -/p at THETA/sub cm/ = 90/sup 0/, -t = 9 GeV/sup 2//c/sup 2/. The apparatus consists of a magnetic spectrometer, with Cerenkov particle identification, which selects stable charged particles (protons in this case) at high momentum near 90/sup 0/ in the center-of-mass. Amore » large aperture array of PWCs observes the recoil particle or charged decay products. Cross sections are extremely low, approximately a 1 nb/(GeV/c)/sup 2/ for elastic scattering. We will report on a sample of more than 1000 ..pi../sup -/p elastic events, and on rho/sup -/p, where the rho/sup -/ decay distribution was observed. We find a surprisingly large rho/sup -/p cross section in this large momentum transfer region, with rho/sup -/p about half the elastic cross section, and a striking spin alignment of the rho/sup -/.« less
125996066
A MULTIKILOTON DETECTOR TO CONDUCT A SENSITIVE SEARCH FOR NUCLEON DECAY
39568649
Evolution of the density parameter in multidimensional cosmology.
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
37516641
Simple hadronic matrix elements with Wilson valence quarks and dynamical staggered fermions at 6/g2=5.6.
We have measured some simple matrix elements for pseudoscalar and vector mesons made of Wilson valance quarks and staggered sea quarks at [beta]=5.6 at sea quark masses [ital am][sub [ital q]]=0.01 and 0.025. Our measurements include the decay constants of pseudoscalars (including [ital f][sub [ital D]]), the wave function at the origin (or decay constant) of vector mesons, and the calculation of quark masses from current algebra. The effects of sea quarks on the simulations are small. We make comparisons to quenched simulations at similar values of the lattice spacing (1/[ital a][congruent]2 GeV).
44737686
Hadron spectrum and matrix elements in QCD with dynamical Wilson fermions at 6/g2=5.3.
We present results of a lattice simulation of quantum chromodynamics with two degenerate flavors of dynamic Wilson fermions at $\frac{6}{{g}^{2}}=5.3$ at each of two dynamical fermion hopping parameters $\ensuremath{\kappa}=0.1670 \mathrm{and} 0.1675$ corresponding to pion masses in lattice units of about 0.45 and 0.31. The simulations include three other values of valence quark mass, in addition to the dynamical quarks. We present calculations of masses and of the decay constants of vector mesons and of pseudoscalars, including the $D$-meson decay constant. The effects of sea quarks on matrix elements and spectroscopy are small.
29084520
Comparison of lattice Coulomb-gauge wave functions in the quenched approximation and with dynamical fermions.
We present a comparison of Coulomb-gauge wave functions from 6/[ital g][sup 2]=6.0 quenched simulations with two simulations which include the effects of dynamical fermions: simulations with two flavors of dynamical staggered quarks and valence Wilson quarks at 6/[ital g][sup 2]=5.6 and simulations with two flavors of dynamical Wilson quarks and Wilson valence quarks at 6/[ital g][sup 2]=5.3. The spectroscopy of these systems is essentially identical. Parametrizations of the wave functions are presented which can be used as interpolating fields for spectroscopy calculations. The sizes of particles are calculated using these parametrized wave functions. The resulting sizes are small, approximately half the sizes of the physical states. The charge radius of the neutron, which provides an indication of the asymmetries between the wave functions of up and down quarks, is calculated. Although the size of the nucleon in these simulations is small, the ratio of the charge radius of the neutron to that of the proton is consistent with the physical value. We find no significant differences between the quenched and dynamical simulations.
37933794
From spectroscopy to the strong coupling constant with heavy Wilson quarks.
In this work we present lattice calculations of the masses of {ital P}-wave mesons using Monte Carlo simulations. Our valence fermions are defined by the Wilson action. Our gauge fields are generated with both dynamical staggered fermions at a lattice coupling {beta}{equivalent_to}6/{ital g}{sup 2}=5.6 for sea quark masses of {ital am}{sub {ital q}}=0.010 and 0.025 and in the quenched approximation at {beta}=6.0. We present results for charm and charmonium spectroscopy and use them to compute the strong coupling constant {alpha}{sub {ital s}}. We compare our results to those of other recent lattice calculations and experiments.