CP Violation in D0−D0‾D^0-\overline{D^0}Mixing

The existence of $D^0-\overline{D^0}$ mixing at a detectable level requires new physics, which effectively yields a $\Delta c = 2$ superweak interaction. In general this interaction may involve significant CP violation. For small values of the mixing it may be much easier to detect the CP-violating part of the mixing than the CP-conserving part.Comment: 3 pages, latex, no figure

Consequences of Approximate S3S_3 Symmetry of the Neutrino Mass Matrix

Assuming that the neutrino mass matrix is dominated by a term with the permutation symmetry $S_{\scriptscriptstyle 3}$ it is possible to explain neutrino data only if the masses are quasi-degenerate. A sub-dominant term with an approximate $\mu -\tau$ symmetry leads to an approximate tri-bimaximal form. Experimental consequences are discussed.Comment: 7 pages, 2 figures, 1 table, RevTe

CP Violation

Three possibilities for the origin of CP violation are discussed: (1) the Standard Model in which all CP violation is due to one parameter in the CKM matrix, (2) the superweak model in which all CP violation is due to new physics and (3) the Standard Model plus new physics. A major goal of B physics is to distinguish these possibilities. CP violation implies time reversal violation (TRV) but direct evidence for TRV is difficult to obtain.Comment: 13 pages, to be published in Lecture Notes of TASI-2000, edited by Jonathan L. Rosner, World Scientific, 200

Toward a Neutrino Mass Matrix

One may identify the general properties of the neutrino mass matrix by generating many random mass matrices and testing them against the results of the neutrino experiments.Comment: 3 pages, 1 figure, talk at DPF200

Is Ue3U_{e3} really related to the solar neutrino solutions?

It has been said that the measurements of $U_{e3}$ in the lepton flavor mixing matrix would help discriminate between the possible solar neutrino solutions under the natural conditions with the neutrino mass hierarchies of $m_1 \ll m_2 \ll m_3$ and $m_1 \sim m_2 \gg m_3$, where $m_i$ is the $i$-th generation neutrino absolute mass. However, it is not true, and the relation between $\sin^2 2 \theta_{12}$ and $U_{e3}$ obtained by Akhmedov, Branco, and Rebelo is trivial in actual. We show in this paper that the value of $U_{e3}$ cannot predict the solar neutrino solutions without one additional nontrivial condition.Comment: 7pages, no figur

Relating the scalar flavour-changing neutral couplings to the CKM matrix

We build a class of two-Higgs-doublet models in which the flavour-changing couplings of the neutral scalars are related in an exact way to elements of the quark mixing matrix. In this framework, we explore the different possibilities for CP violation and find some interesting scenarios, like a realization of the superweak idea without CP violation in the $B$-meson system. In another scenario the neutral scalars can be relatively light, and their contributions to the $B^0$--$\bar{B}^0$ transitions can alter the standard-model predictions for CP violation in that system.Comment: 12 pages LATEX, no figure

Exact Parametrization of Majorana Neutrino Mass Matrix with Large Mixing

Under the assumption that the neutrinos are Majorana particles we study how the lepton mass matrices can be transformed into the simple form which has the same physical quantities by removing redundant parameters. We propose the exact parametrization of the lepton mass matrices which reflects the small nu_e-nu_mu mixing and the large nu_mu-nu_tau mixing. The relations between the twelve parameters and the physical quantities are shown. Furthermore we calculate the MNS matrix by applying the assumptions used in the quark sector. Finally we also check the validity of these assumptions from the experimental values.Comment: 11 pages, LaTeX, no figure

Neutrinoless Double Beta Decay and CP Violation

We study the relation between the Majorana neutrino mass matrices and the neutrinoless double beta decay when CP is not conserved. We give an explicit form of the decay rate in terms of a rephasing invariant quantity and demonstrate that in the presence of CP violation it is impossible to have vanishing neutrinoless double beta decay in the case of two neutrino generations (or when the third generation leptons do not mix with other leptons and hence decouple).Comment: 9 pages, UTPT-93-1

Comment on ``Neutrino masses and mixing angles in a predictive theory of fermion masses''

In the extension of the Dimopoulos--Hall--Raby model of the fermion mass matrices to the neutrino sector, there is an entry in the up-quark and neutrino Dirac mass matrices which can be assumed to arise from the Yukawa coupling of a {\bf 120}, instead of a {\bf 10} or a {\bf 126}, of SO(10). Although this assumption leads to an extra undetermined complex parameter in the model, the resulting lepton mixing matrix exhibits the remarkable feature that the $\nu_{\tau}$ does not mix with the other two neutrinos. Making a reasonable assumption about the extra parameter, we are able to fit the large-mixing-angle MSW solution of the solar-neutrino problem, and we obtain $m_{\nu_{\tau}} \sim 10$ eV, the right mass range to close the Universe. Other possibilities for explaining the solar-neutrino deficit are also discussed.Comment: standard LATEX, 6 pages, 2 figures available from the authors, report No. CMU-HEP93-20 and DOE-ER/40682-4

B Physics - A Theoretical Review

This overview of what we can hope to learn from high-statistics experiments in B physics in the next few years includes: (a) a review of parameters of the Cabibbo-Kobayashi-Maskawa (CKM) Matrix; (b) direct determination of magnitudes of CKM elements; (c) forthcoming information from studies of kaons; (d) CP violation in B decays; (e) aspects of rate measurements; (f) the role of charm-anticharm annihilation; (g) remarks on tagging; and (h) effects beyond the standard model.Comment: 23 pages, latex, 4 figures, further corrections to reference