摘要:

The electroweak interactions are based on an extension of the electromagnetic (Maxwell) interactions, realized in a rather odd way so that the symmetries of the theory are not immediately obvious. This “broken” theory has been the subject of intense investigation at LEP, and has passed all tests with flying colors. These lectures are meant to complement the many excellent presentations of the StandardSU(2)L×U(1)Yelectroweak interactions in three main ways: first to clarify the physical meaning of symmetries in particle physics, second, to summarize the recent tests of the standard model using LEP data, and finally to look at possible roles of gravity in understanding mass. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374865

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

In a model with a gauge groupGSM⊗U(1)X,whereGSMis the standard model gauge group andU(1)Xis a horizontal local gauge symmetry, we propose a radiative generation of the spectrum of quark masses and mixing angles. The assignment of horizontal charges is such that at tree level only the third family is massive. The numerical fit results are shown. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374866

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We study the conditions under which flavor violation arises in a left-right mirror model that includes additional fermions with mirror properties for vector and scalar interactions. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374867

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The&Dgr;++magnetic dipole moment is determined within a full dynamical and gauge invariant model. Using the same model the coupling constants that determine the M1 and E2 contributions to the pion photoproduction transition are also analyzed. First we study the elastic&pgr;+pand radiative&pgr;+p&ggr;scattering within a complex mass scheme which incorporates the finite width of the&Dgr;++resonance. The amplitudes for both processes are invariant under contact transformations that left invariant Lagrangians with the spin 3/2 fields and gauge-invariance is fulfilled for the radiative case. The pole parameters of the&Dgr;++obtained by fitting the experimental elastic cross section arem&Dgr;=(1211.9±0.5)&hthinsp;MeVand&Ggr;&Dgr;=(84.9±0.4)&hthinsp;MeV.The anomalous magnetic dipole moment of the&Dgr;++is left as the only adjustable parameter in radiative&pgr;+p&ggr;scattering. It was fixed by comparison with the experimental bremsstrahlung differential cross section in the case of most sensible photon geometries. In addition the coupling constants G1 and G2 of the&ggr;N→&Dgr;vertex are fitted to reproduced pion photoproduction cross section. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374868

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The one loop Renormalization Group Equations for the Yukawa couplings of quarks are solved. From the solution we find the explicit energy dependence ont=ln&hthinsp;E/&mgr;of the evolution of thedownquark massesq=d,s,bfrom the grand unification scale down to the top quark massmt.These results together with the earlier published evolution of theupquark masses completes the pattern of the evolution of the quark masses. We also find the energy dependence of the absolute values of the Cabibbo-Kobayashi-Maskawa (CKM) matrix|Vij|.The interesting property of the evolution of the CKM matrix and the ratios of the quark masses:mu,c/mtandmd,s/mbis that they all depend ontthrough only one function of energyh(t).©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374869

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We evaluate the compositeness effects of leptons on the vertexW&tgr;&ngr;&tgr;in the context of an effective Lagrangian approach and get the corrections to the non universal couplingg&tgr;where we consider that only the third family is composed. We find the allowed region from the experimentalg&tgr;/gequotient for (&Lgr; versusm*) plane when the masses of the excited states of the third generation are considered equal, i.e.,m&tgr;*=m&Vthgr;&tgr;*=m*.©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374870

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We develop one-loop effective vertices and propagators in the linear sigma model at finite temperature satisfying the chiral Ward identities and use these in turn to compute the pion dispersion relation in a pion medium for small momentum and temperatures on the order of the pion mass at next to leading order in the parameterm&pgr;2/4&pgr;2f&pgr;2and to zeroth order in the parameter(m&pgr;/m&sgr;)2.We show that this expansion reproduces the result obtained from chiral perturbation theory at leading order. The main effect is a perturbative, temperature-dependent increase of the pion mass. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374871

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We show that in the presence of primordial magnetic fields, it is possible to produce a large enough amount ofCPviolation to possibly explain the baryon asymmetry of the universe. This can happen during the reflection of fermions off the true vacuum bubbles nucleated during a first order phase transition. The chiral nature of the fermion coupling to the background field in the symmetric phase can be used to construct two-fermion interference processes in analogy to the Bohm-Aharanov effect. By describing the transport of theCPasymmetry into the symmetric phase, it is possible to generate a baryon to entropy ratio&rgr;B/s=(3−6)×10−11,which is close to the observed value based on uncleosynthesis considerations. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374872

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The purpose of this talk is reanalyze the charged current (CC) cross section neutrino-nucleon with particular attention to the energy rangeE&ngr;⩽10&hthinsp;GeVintroducing new experimental data concerning to form factors involved in the calculations, and discuss possible consequences for the interpretation of the measurements of the atmospheric fluxes obtained by deep underground detectors. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374873

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The production of Higgs boson at Tevatron by gluon fusion, can be enhanced by the presence of heavy colored particles that receive their mass from the SM Higgs. This can be used to constraint additional standard or mirror families, chiral colored sextets and octet quarks. The possibility to detect the lepton-flavor violating Higgsh→&tgr;&mgr;/&tgr;e,at the first stages of RUN-II is also discussed. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1374874

出版商:AIP    

年代:1901

数据来源: AIP