Search for T-violation in K^+ --> pi^0 mu^+ nu and K^+ --> mu^+ nu gamma Decays

The recent progress in search for T-violating transverse muon polarization in the decays K^+ --> pi^0 mu^+ nu and K^+ --> mu^+ nu gamma in the on-going experiment E246 at KEK is reported. Future prospects in polarization measurements are also discussed.Comment: 11 pages, 5 figures, talk at the Conference of Nuclear Physics Department RAS, 27 November - 1 December 2000, ITEP, Mosco

About estimations of an one-photon background in neutrino oscillation experiments at low neutrino energies

The possible sources of one-photon radiation as background for quasi-elastic reaction nu_mu+n to mu^-+p are considered. The ones are relevant in experiments on determination of oscillation parameters at low neutrino energies (E_nu^lab~1 GeV). The estimation for the cross section of reaction nu_mu+n to mu^-+p+gamma is given at E_nu^lab=0.7 GeV as 0.65% from the corresponding cross section of quasi-elastic reaction.Comment: 17 pages, 10 figure

Tests of the Standard Model Using Muon Polarization Asymmetries in Kaon Decays

We have examined the physics and the experimental feasibility of studying various kaon decay processes in which the polarization of a muon in the final state is measured. Valuable information on CP violation, the quark mixing (CKM) matrix, and new physics can be obtained from such measurements. We have considered muon polarization in K_L to mu+ mu- and K to pi mu+ mu- decays. Although the effects are small, or difficult to measure because of the small branching ratios involved, these studies could provide clean measurements of the CKM parameters. The experimental difficulty appears comparable to the observation of K to pi nu barnu. New sources of physics, involving non-standard CP violation, could produce effects observable in these measurements. Limits from new results on the neutron and electron electric dipole moment, and epsilon-prime over epsilon in neutral kaon decays, do not eliminate certain models that could contribute to the signal. A detailed examination of muon polarization out of the decay plane in KMU3 and radiative KMU2 decays also appears to be of interest. With current kaon beams and detector techniques, it is possible to measure the T-violating polarization for KMU3 with uncertainties approaching 0.0001. This level of sensitivity would provide an interesting probe of new physics.Comment: 24 pages, 3 figures, To be published in the International Journal of Modern Physics

T-odd correlation in the K+ ->pi l nu gamma decays beyond Standard Model

The dependence of the T-odd correlation on the effective Lagrangian parameters in the $K^+ \to \pi l \nu \gamma, l=e, \mu$ decays is analyzed. It is shown that the introduced observable is perspective in a search for new physics in the vector and pseudovector sector of the Lagrangian. As for scalar and pseudoscalar sectors, the T-odd correlation studies will not allow one to improve current restrictions on parameters of models beyond SM.Comment: 18 pages, 1 figur

The Ω\Omega and Σ0\Sigma^0-Λ\Lambda transition magnetic moments in QCD sum rules

The method of QCD sum rules in the presence of external elctromagnetic fields is used to calculate the $\Omega$ magnetic moment $\mu_{\Omega^-}$ and $\Sigma^0$-$\Lambda$ transition magnetic moment $\mu_{\Sigma^0\Lambda}$, with the susceptibilities obtained previously from the study of octet baryon magnetic moments. The results $\mu_{\Omega^-}=-1.92\mu_N$ and $\mu_{\Sigma^0\Lambda}=1.5\mu_N$ are in good agreement with the recent experimental data