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

Masses and Mixings from Neutrino Beams pointing to Neutrino Telescopes

We discuss the potential to determine leading oscillation parameters, the value and the sign of \Delta m^2_{31}, as well as the magnitude of \sin^2 2\theta_{13} using a conventional wide band neutrino beam pointing to water or ice Cherenkov neutrino detectors known as ``Neutrino Telescopes''. We find that precision measurements of \Delta m^2_{31} and \theta_{23} are possible and that, even though it is not possible to discriminate between charges in the detector, there is a remarkably good sensitivity to the mixing angle \theta_{13} and the sign of \Delta m^2_{31}.Comment: 9 pages, 4 figure

Desperately Seeking Non-Standard Phases via Direct CP Violation in b→sg∗b\to sg^\ast Process

Attributing the recent CLEO discovery of $B \to \eta' + X_s$ to originate (primarily) from the fragmentation of an off-shell gluon ($g^*$) via $b \to s + g^*$, $g^* \to g + \eta'$, we emphasize that many such states ($X_g$) should materialize. Indeed the hadronic fragments ($X_g$) of $g^*$ states are closely related to those seen in $\psi \to \gamma (\phi, \omega) + X_g$. A particular final state of considerable interest is $X_g=K^+K^-$. Signals from such states in $B$ decays can be combined to provide a very sensitive search for CP violating phase(s) from non-standard physics. The method should work even if the contribution of these source(s) to the rates is rather small ($\sim10$) to the point that a comparison between theory and experiment may find it extremely difficult to reveal the presence of such a new physics.Comment: 16 pages, 5 figure

The τ\tau neutrino as a Majorana particle

A Majorana mass term for the $\tau$ neutrino would induce neutrino - antineutrino mixing and thereby a process which violates fermion number by two units. We study the possibility of distinguishing between a massive Majorana and a Dirac $\tau$ neutrino, by measuring fermion number violating processes in a deep inelastic scattering experiment $\nu p \rightarrow \tau X$. We show that, if the neutrino beam is obtained from the decay of high energetic pions, the probability of obtaining "wrong sign" $\tau$ leptons is suppressed by a factor ${\cal{O}}(m_{\nu_{\tau}}^2 \theta^2/m_{\mu}^2)$ instead of the naively expected suppression factor $\theta^2 m_{\nu_{\tau}}^2/E_{\nu}^2$, where $E_{\nu}$ is the $\tau$ neutrino energy, $m_{\nu_{\tau}}$ and $m_{\mu}$ are the $\tau$-neutrino and muon masses, respectively, and $\theta$ is the $\nu_{\mu}$ - $\nu_{\tau}$ mixing angle. If $m_{\nu_{\tau}}$ is of the order of 10 MeV and $\theta$ is of the order of $0.01 - 0.04$ (the present bounds are ($m_{\nu_{\tau}} < 35 MeV, \theta < 0.04$) the next round of experiments may be able to distinguish between Majorana and Dirac $\tau$-neutrinos.Comment: 14 pages, 4 figures (not included), MPI-Ph/93-4

Detecting New Physics from CP-violating phase measurements in B decays

The standard CKM model can be tested and New Physics detected using only CP-violating phase measurements in B decays. This requires the measurement of a phase factor which is small in the Standard Model, in addition to the usual large phases $\beta$ and $\gamma$. We also point out that identifying violations of the unitarity of the CKM matrix is rather difficult, and cannot be done with phase measurements alone.Comment: 6 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

Neutrino oscillation in a space-time with torsion

Using the Einstein-Cartan-Dirac theory, we study the effect of torsion on neutrino oscillation. We see that torsion cannot induce neutrino oscillation, but affects it whenever oscillation exists for other reasons. We show that the torsion effect on neutrino oscillation is as important as the neutrino mass effect, whenever the ratio of neutrino number density to neutrino energy is $\sim 10^{69}$ cm$^{-3}$ /eV, or the number density of the matter is $\sim 10^{69}$ cm$^{-3}$.Comment: 7 pages, LaTex,Some typos corrected Journal: Int. J. Mod. Phys. A (1999) (will be appeared

Systematic Exploration of the Neutrino Factory Parameter Space including Errors and Correlations

We discuss in a systematic way the extraction of neutrino masses, mixing angles and leptonic CP violation at neutrino factories. Compared to previous studies we put a special emphasis on improved statistical methods and on the multidimensional nature of the combined fits of the nu_e -> nu_mu, \bar nu_e -> \bar nu_mu appearance and nu_mu -> nu_mu, \bar nu_mu -> \bar nu_mu disappearance channels. Uncertainties of all involved parameters and statistical errors are included. We find previously ignored correlations in the multidimensional parameter space, leading to modifications in the physics reach, which amount in some cases to one order of magnitude. Including proper statistical errors we determine for all parameters the improved sensitivity limits for various baselines, beam energies, neutrino fluxes and detector masses. Our results allow a comparison of the physics potential for different choices of baseline and beam energy with regard to all involved parameters. In addition we discuss in more detail the problem of parameter degeneracies in measurements of delta_CP.Comment: 29 pages, 14 fugure

Flavour-conserving oscillations of Dirac-Majorana neutrinos

We analyze both chirality-changing and chirality-preserving transitions of Dirac-Majorana neutrinos. In vacuum, the first ones are suppressed with respect to the others due to helicity conservation and the interactions with a (``normal'') medium practically does not affect the expressions of the probabilities for these transitions, even if the amplitudes of oscillations slightly change. For usual situations involving relativistic neutrinos we find no resonant enhancement for all flavour-conserving transitions. However, for very light neutrinos propagating in superdense media, the pattern of oscillations $\nu_L \to \nu^C_L$ is dramatically altered with respect to the vacuum case, the transition probability practically vanishing. An application of this result is envisaged.Comment: 14 pages, latex 2E, no figure

Non-universal gravitational couplings of neutrinos in matter

When neutrinos travel through a normal matter medium, the electron neutrinos couple differently to gravity compared to the other neutrinos, due to the presence of electrons in the medium and the absence of the other charged leptons. The matter-induced gravitational couplings of the neutrinos under such conditions are calculated and their contribution to the neutrino index of refraction in the presence of a gravitational potential is determined.Comment: Latex, 10 page