摘要:

We review the latest experimental results in searching for “direct”CP-violation by measuring theCP-violating parametersRe(&egr;′/&egr;)in neutral kaon decays. Recent result from Fermilab-KTeVRe(&egr;′/&egr;)=(28.0±4.1)×10−4,and new preliminary result from CERN-NA48Re(&egr;′/&egr;)=(14.0±4.3)×10−4,are presented. Both experiments, though using very different techniques, have now performed very well by collecting millions of events for all four relevant decay modes ofKL,Sto&pgr;+&pgr;−and&pgr;0&pgr;0simultaneously. The current world average on this important measurement isRe(&egr;′/&egr;)=(19.3±2.4)×10−4with a&khgr;2/ndf=11.1/5,establishing the existence of “direct”CP-violation. The experimental status of such crucial measurements and the future prospects are also discussed here. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1330896

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We summarize the present status of CP violation discussing in particular the standard analysis of the unitarity triangle and the ratio&egr;′/&egr;including most recent developments. The perspectives in this field include in particular B decays, rare K decays such asKL→&pgr;0&ngr;&ngr;¯andKL→&pgr;0e+e−and the improved standard analysis of the unitarity triangle through the measurement ofBs0−B¯s0mixing. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1330897

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Recent data from Super-Kamiokande on solar and atmospheric neutrinos and their constraints on the neutrino mass and mixing are presented. Also results on proton decay searches are presented. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1330898

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Isospin-breaking effects, in particular those associated with electroweak-penguin contributions and&pgr;0−&eegr;,&eegr;′mixing, have long been known to affect the Standard Model prediction of&egr;′/&egr;in a significant manner. We have found an heretofore unconsidered isospin-violating effect of importance; namely, theu-dquark mass difference can spawn|&Dgr;I|=3/2components in the matrix elements of the gluonic penguin operators. Using chiral perturbation theory and the factorization approximation for the hadronic matrix elements, we find within a specific model for the low-energy constants that we can readily accommodate an increase in&egr;′/&egr;by a factor of two. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1330899

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

A finite energy sum rule (FESR) analysis of the isospin-breaking vector current correlator⟨0|T(V&mgr;3V&ngr;8)|0⟩is used to determine the isospin-breaking electromagnetic (EM) decay constants of the low-lying vector mesons. These results are used to evaluate the corrections required to extract the flavor diagonal 33 and 88 resonance contributions from the full resonance EM contributions to the EM spectral function. A large (∼15&percent;) correction is found in the case of the &ohgr; contribution to the isoscalar spectral function. The implications of these results for sum rules based on the isovector-isoscalar spectral difference are considered. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1330900

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Within the framework of three lepton families I present a transparent analytical relationship between the neutrino mixing and CP-violating parameters in vacuum and those in matter. Such a model- and parametrization-independent result will be particularly useful to recast the fundamental lepton flavor mixing matrix from the future long-baseline neutrino experiments. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1330901

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Recent Tritium beta decay experiments continue to exhibit an excess of counts near the end point. The representation of the data in terms of the extracted mass squared can be reproduced by allowing interference between the Standard Model V-A current and other Lorentz currents allowed by existing experimental limits. This is true only if the electron antineutrino is nearly, but not exactly, a single mass eigenstate with a mixing probability to other mass eigenstates of the order of a few parts per thousand, and if the mass of that eigenstate is a few electron volts. In conjunction with double beta decay constraints, this precludes a solitary Majorana neutrino in the electron family. Combining this with solar neutrino results leads to pseudo-Dirac neutrinos and implies that neutral current events in SNO will suffer the same suppression as charge current events. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1330902

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Time-Reversal-Invariance non-conservation has for the first time been unequivocally demonstrated in a direct measurement, one of the results of the CPLEAR experiment. What is the situation then with regard to time-reversal-invariance non-conservation in systems other than the neutral kaon system? Two classes of tests of time-reversal-invariance need to be distinguished: the first one deals with parity violating (P-odd)/time-reversal-invariance non-conserving (T-odd) interactions, while the second one deals with P-even/T-odd interactions (assuming CPT conservation this implies C-conjugation non-conservation). Limits on a P-odd/T-odd interaction follow from measurements of the electric dipole moment of the neutron. This in turn provides a limit on a P-odd/T-odd pion-nucleon coupling constant which is10−4times the weak interaction strength. Limits on a P-even/T-odd interaction are much less stringent. The better constraint stems also from the measurement of the electric dipole moment of the neutron. Of all the other tests, measurements of charge-symmetry breaking in neutron-proton elastic scattering provide the next better constraint. The latter experiments were performed at TRIUMF (at 477 and 347 MeV) and at IUCF (at 183 MeV). Weak decay experiments (the transverse polarization of the muon inK+→&pgr;0&mgr;+&ngr;&mgr;and the transverse polarization of the positrons in polarized muon decay) have the potential to provide comparable or possibly better constraints. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1330903

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

In order to understand QCD at the energies relevant to hadronic physics one requires analytical methods for dealing with relativistic gauge field theories at large couplings. Strongly coupled quenched QED provides an ideal laboratory for the development of such techniques, in particular as many calculations suggest that—like QCD—this theory has a phase with broken chiral symmetry. In this talk we report on a nonperturbative variational calculation of the electron propagator within quenched QED and compare results to those obtained in other approaches. We find surprising differences among these results. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1330904

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

I discuss CP violation in&Lgr;→p&pgr;−comparing the standard model expectations with what could happen in new physics scenarios. I point out that Fermilab experiment E871 is sensitive to some of these scenarios. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1330905

出版商:AIP    

年代:1900

数据来源: AIP