摘要:

We consider the bubbles of quark matter which survived the confinement phase transition in the universe at high temperature. With the constraint of being neutral and of conservation of baryonic number, we obtain the evolution of the density of quarks of different flavours and of pressure till their contraction stops. On the other hand we find that at low temperature and increasing pressure, a system of ordinary quarks chooses to acquire a strange component. This is what might happen in neutron stars becoming sources of strangelets. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1594381

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Most of the baryons produced from unpolarized p‐Nucleus collisions are polarized. The most studied baryon is &Lgr;0from p‐Nucleus in both inclusive and exclusive reactions; &Lgr;0polarization is described byP(Xf,Pt) =aXfPt; where a is independent of the beam energy but dependent on the target. The above equation fits very well, within statistical errors, &Lgr;¯0polarization produced in inclusive reactions. The polarization of &Lgr;¯0from inclusivep¯preactions is consistent with &Lgr;0polarization from inclusiveppreactions. The parameterais independent of the beam energy but depends on the nature of the target or beam: forp¯preactions,a= 0.280 ± 0.0280,&khgr;2dof = 1.281; forK+preactionsa= 1.142±0.231,&khgr;2dof = 0.931; forpBereactions,a= 0.027 ± 0.035,&khgr;2dof = 0.502; for &Sgr;−(C+Cu) reactions,a= 0.069 ± 0.110,&khgr;2dof = 0.464. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1594382

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We report on the measurement of the lifetimes of pions, kaons and muons in the secondary cosmic‐ray radiation by using a hybrid detector. The detector consists of a container filled with liquid scintillator that produces scintillation light when crossed by charged particles; this container is located atop a water tank that produces Cherenkov light when crossed by charged particles. Both containers have one phototube inside to detect the light produced. The electronics used consists of NIM modules, two digital oscilloscopes and one PC. This equipment is multipurpose and can be conventionally found in any modern physics laboratory. The results obtained for the muon, pion and kaon lifetimes are the following: &tgr;&mgr;=2.120±0.02 &mgr;s, &tgr;&pgr;=24.63±3 ns y &tgr;K= 12.52±2 ns in good agreement with the literature. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1594383

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The highlights of an effective Lagrangian analysis of the lepton‐flavor violating reaction &mgr;−&mgr;+→ &mgr;±&tgr;∓are presented. We consider the scenario in which the lepton flavor violation is induced by the Higgs scalar boson. Further results will be presented elsewhere. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1594384

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We present a preliminary study of production of hyperons, starting with &Lgr;0, in 500 GeV/c &pgr;−‐ nucleon interactions. These processes occur at lowpT2and not very high energy(s ≈ 30 GeV), then we can use the Dual Parton Model. In the frame of this model we use the graphs of interchange of pomerons to calculate the cross section production of &Lgr;0and &Lgr;¯0as function of the Feymann variablexF. We calculate as well the asymmetry asxFfunction and compare with the experimental results of the E791 experiment at Fermilab. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1594385

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We model hadronic matter in terms of its quark constituents by taking into account its internal flavor (u,d,s) and 3 colors degrees of freedom within the string‐flip model, which has quark clustering at low density, color deconfinement at high density, and dynamically interpolates between both limits via a many‐body potential that simulates the gluon flux tubes. A variational Monte Carlo simulation in 3 spatial dimensions is performed to study the transition to strange matter from both a non‐relativistic and a semi‐relativistic approach. The non‐relativistic one shows that the system has continuous and discontinuous phase transitions while the semi‐relativistic approach has purely continuous transitions. In both cases clustering correlations are found to remain important in the strange matter domain and strange matter to be absolutely stable. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1594386

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We study a nonlocal Dirac operator that preserves chiral symmetry an uniqueness. It is shown that this operator approaches to an ultralocal operator when the size of the lattice tends to zero. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1594387

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We present an alternative formalism to the Rarita‐Schwinger framework for the description of “has‐been” higher‐spins at rest that avoids the Velo‐Zwanziger problem. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1594388

出版商:AIP    

年代:1903

数据来源: AIP