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

Constraining the CKM Parameters using CP Violation in semi-leptonic B Decays

We discuss the usefulness of the CP violating semi-leptonic asymmetry a_{SL} not only as a signal of new physics, but also as a tool in constraining the CKM parameters. We show that this technique could yield useful results in the first years of running at the B factories. We present the analysis graphically in terms of M_{12}, the dispersive part of the B-Bbar mixing amplitude. This is complementary to the usual unitarity triangle representation and often allows a cleaner interpretation of the data.Comment: 15 pages REVTEX, 7 figure

Towards granular hydrodynamics in two-dimensions

We study steady-state properties of inelastic gases in two-dimensions in the presence of an energy source. We generalize previous hydrodynamic treatments to situations where high and low density regions coexist. The theoretical predictions compare well with numerical simulations in the nearly elastic limit. It is also seen that the system can achieve a nonequilibrium steady-state with asymmetric velocity distributions, and we discuss the conditions under which such situations occur.Comment: 8 pages, 9 figures, revtex, references added, also available from http://arnold.uchicago.edu/?ebn

A Consistent Resolution of Possible Anomalies in B^0 --> phi K_S and B^+ --> eta' K^+ Decays

In the framework of R-parity violating (\rpv) supersymmetry, we try to find a consistent explanation for both recently measured CP asymmetry in B^0 --> phi K_S decay and the large branching ratio of B^{+/-} --> eta' K^{+/-} decay, which are inconsistent with the Standard Model (SM) prediction. We also investigate other charmless hadronic B --> PP and B --> VP decay modes whose experimental data favor the SM: for instance, recently measured CP asymmetries in B^0 --> eta^{prime} K_S and B^0 --> J / Psi K_S. We find that all the observed data can be accommodated for certain values of \rpv couplings.Comment: 14 pages, 2 figures, Revtex, minor changes, to appear in Phys. Rev. Let

Quark-Lepton Symmetry In Five Dimensions

We construct a complete five dimensional Quark-Lepton symmetric model, with all fields propagating in the bulk. The extra dimension forms an $S^1/Z_2\times Z_2'$ orbifold with the zero mode fermions corresponding to standard model quarks localised at one fixed point. Zero modes corresponding to left(right)-chiral leptons are localised at (near) the other fixed point. This localisation pattern is motivated by the symmetries of the model. Shifting the right-handed neutrinos and charged leptons slightly from the fixed point provides a new mechanism for understanding the absence of relations of the type $m_e=m_u$ or $m_e=m_d$ in Quark-Lepton symmetric models. Flavour changing neutral currents resulting from Kaluza Klein gluon exchange, which typically arise in the quark sector of split fermion models, are suppressed due to the localisation of quarks at one point. The separation of quarks and leptons in the compact extra dimension also acts to suppress the proton decay rate. This permits the extra dimension to be much larger than that obtained in a previous construct, with the bound $1/R\gtrsim30$ TeV obtained.Comment: 12 pages, references added to match published versio

CP Violation in Supersymmetric Theories: stop2->stop1 H H, stop2->stop1 Z Z, stop2->stop1 W+ W-, stop2->stop1 Z H

We study the decays stop2->stop1 H H, stop2->stop1 Z Z, stop2->stop1 W+ W- and stop2->stop1 Z H, with an eye towards measuring the CP-violating supersymmetric parameters contained in these processes. We find that stop2->stop1 H H tends to have the largest CP asymmetry and width, and is perhaps the most favourable experimentally. These decays are sensitive primarily to phi_At, the phase of the trilinear coupling A_t.Comment: 15 pages, 3 figures. Comments added; figure changed. Analysis and conclusions unchange

Sneutrino-Antisneutrino Mixing and Neutrino Mass in Anomaly--mediated Supersymmetry Breaking Scenario

In supersymmetric models with nonzero Majorana neutrino mass, the sneutrino and antisneutrino mix, which may lead to same sign dilepton signals in future collider experiments. We point out that the anomaly-mediated supersymmetry breaking scenario has a good potential to provide an observable rate of such signals for the neutrino masses suggested by the atmospheric and solar neutrino oscillations. The sneutrino mixing rate is naturally enhanced by m_{3/2}/m_{\tilde{\nu}}={\cal O}(4\pi/\alpha) while the sneutrino decay rate is small enough on a sizable portion of the parameter space. We point out also that the sneutrino-antisneutrino mixing can provide much stronger information on some combinations of the neutrino masses and mixing angles than neutrino experiments.Comment: Revtex, 13 pages, 2 figure

A consistent picture for large penguins in D -> pi+ pi-, K+ K-

A long-standing puzzle in charm physics is the large difference between the D0 -> K+ K- and D0 -> pi+ pi- decay rates. Recently, the LHCb and CDF collaborations reported a surprisingly large difference between the direct CP asymmetries, Delta A_CP, in these two modes. We show that the two puzzles are naturally related in the Standard Model via s- and d-quark "penguin contractions". Their sum gives rise to Delta A_CP, while their difference contributes to the two branching ratios with opposite sign. Assuming nominal SU(3) breaking, a U-spin fit to the D0 -> K+ pi-, pi+ K-, pi+ pi-, K+ K- decay rates yields large penguin contractions that naturally explain Delta A_CP. Expectations for the individual CP asymmetries are also discussed.Comment: 24 pages, 8 figure

Leptonic Flavor and CP Violation

We discuss how neutrino oscillation experiments can probe new sources of leptonic flavor and CP violation.Comment: 8 pages, latex, no figures. Invited talk given at KAON 2001, Pisa, Italy, June 12 - 17, 200

CP Violation in \tau ->\nu\pi K_S and D->\pi K_S: The Importance of K_S-K_L Interference

The $B$-factories have measured CP asymmetries in the $\tau\to\pi K_S\nu$ and $D\to K_S\pi$ modes. The $K_S$ state is identified by its decay to two pions at a time that is close to the $K_S$ lifetime. Within the Standard Model and many of its extensions, the asymmetries in these modes come from CP violation in $K^0-\bar{K}^0$ mixing. We emphasize that the interference between the amplitudes of intermediate $K_S$ and $K_L$ is as important as the pure $K_S$ amplitude. Consequently, the measured asymmetries depend on the times over which the relevant decay rates are integrated and on features of the experiment.Comment: 4 pages, 4 figure