Search

We study the robustness of the determination of the neutrino masses and mixing from the analysis of atmospheric and K2K data under the presence of different forms of phenomenologically allowed new physics in the nu_mu--nu_tau sector. We focus on vector and tensor-like new physics interactions which allow us to treat, in a model independent way, effects due to the violation of the equivalence principle, violations of the Lorentz invariance both CPT conserving and CPT violating, non-universal couplings to a torsion field and non-standard neutrino interactions with matter. We perform a global analysis of the full atmospheric data from SKI together with long baseline K2K data in the presence of nu_mu -> nu_tau transitions driven by neutrino masses and mixing together with sub-dominant effects due to these forms of new physics. We show that within the present degree of experimental precision, the extracted values of masses and mixing are robust under those effects and we derive the upper bounds on the possible strength of these new interactions in the nu_mu--nu_tau sector., 22 pages, LaTeX file using RevTEX4, 5 figures and 4 tables included

We study the status of the CPT violating neutrino mass spectrum which has been proposed to simultaneously accommodate the oscillation data from LSND, KamLAND, atmospheric and solar neutrino experiments, as well as the non-observation of anti-neutrino disappearance in short-baseline reactor experiments. We perform a three-generation analysis of the global data with the aim of elucidating the viability of this solution. We find no compatibility between the results of the oscillation analysis of LSND and all-but-LSND data sets below 3$\sigma$ CL. Furthermore, the global data without LSND show no evidence for CPT violation: the best fit point of the all-but-LSND analysis occurs very close to a CPT conserving scenario., Comment: Improved version, to appear in Phys. Rev. D, 16 pages, 5 figures

Measurements of CP--violating observables in neutrino oscillation experiments have been studied in the literature as a way to determine the CP--violating phase in the mixing matrix for leptons. Here we show that such observables also probe new neutrino interactions in the production or detection processes. Genuine CP violation and fake CP violation due to matter effects are sensitive to the imaginary and real parts of new couplings. The dependence of the CP asymmetry on source--detector distance is different from the standard one and, in particular, enhanced at short distances. We estimate that future neutrino factories will be able to probe in this way new interactions that are up to four orders of magnitude weaker than the weak interactions. We discuss the possible implications for models of new physics., ReVTeX, 28 pages, 7 figues. v2: Modifications in section VIII to reflect the fact that some of the couplings that were discussed in this section are irrelevant to our analysis (as pointed out in hep-ph/0112329); Added a discussion in section IX of the relevance of other future experiments that will search for lepton flavor violation

We calculate the production of 2 b-quark pairs in hadron collisions. Sources of multiple pairs are multiple interactions and higher order perturbative QCD mechanisms. We subsequently investigate the competing effects of multiple b-pair production on measurements of CP-violation: i) the increase in event rate with multiple b-pair cross sections which may reach values of order 1 barn in the presence of multiple interactions and ii) the dilution of $b$ versus $\bar b$ tagging efficiency because of the presence of events with 4 $B$-mesons. The impact of multiple $B$-meson production is small unless the cross section for producing a single pair exceeds 1~mb. We show that even for larger values of the cross section the competing effects i) and ii) roughly compensate so that there is no loss in the precision with which CP-violating CKM angles can be determined., Comment: 14 pages, Latex file using ReVTeX. 7 figures. To Appear in Phys Rev D