1,453 research outputs found

### CP Violation in $D^0-\overline{D^0}$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 $S_3$ 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 $U_{e3}$ 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

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