Measurement of ϕs\phi_s at D{\O} Experiment

Recent measurements of the D\O\ experiment related to the search for new phenomena beyond the Standard Model are reviewed. The new measurement of the like-sign dimuon charge asymmetry reveals a 3.2$\sigma$ deviation from the SM prediction, while the updated study of the $B_s \to J/\psi \phi$ decay demonstrates a better agreement with the SM. All experimental results on the $CP$ violation in mixing are currently consistent with each other. The D\O\ collaboration has much more statistics to analyze, and all these results can be significantly improved in the future.Comment: Proceedings of CKM2010, the 6th International Workshop on the CKM Unitarity Triangle, University of Warwick, UK, 6-10 September 201

Heavy Flavour results from Tevatron

The CDF and D0 experiments finalize the analysis of their full statistics collected in the $p \bar p$ collisions at a center-of-mass energy of $\sqrt{s} = 1.96$ TeV at the Fermilab Tevatron collider. This paper presents several new results on the properties of hadrons containing heavy $b$- and $c$-quarks obtained by both collaborations. These results include the search for the rare decays $B^0, B^0_s \to \mu^+ \mu^-$ (CDF), the study of CP asymmetry in $B_s \to J\psi \phi$ decay (CDF, D0), the measurement of the like-sign dimuon charge asymmetry (D0), the measurement of CP asymmetry in $D^0 \to K^+K^-$ and $D^0 \to \pi^+\pi^-$ decays (CDF), and the new measurement of the $B_s \to D_s^{(*)+} D_s^{(*)-}$ branching fraction (CDF). Both experiments still expect to produce more results on the properties of heavy flavours.Comment: Contribution to the XLVIIth Rencontres de Moriond session devoted to Electroweak Interactions and Unified Theorie

Causality in Spin Foam Models

We compute Teitelboim's causal propagator in the context of canonical loop quantum gravity. For the Lorentzian signature, we find that the resultant power series can be expressed as a sum over branched, colored two-surfaces with an intrinsic causal structure. This leads us to define a general structure which we call a ``causal spin foam''. We also demonstrate that the causal evolution models for spin networks fall in the general class of causal spin foams.Comment: 19 pages, LaTeX2e, many eps figure

Production of Polarized Vector Mesons off Nuclei

Using the light-cone QCD dipole formalism we investigate manifestations of color transparency (CT) and coherence length (CL) effects in electroproduction of longitudinally (L) and transversally (T) polarized vector mesons. Motivated by forthcoming data from the HERMES experiment we predict both the A and Q^2 dependence of the L/T- ratios, for rho^0 mesons produced coherently and incoherently off nuclei. For an incoherent reaction the CT and CL effects add up and result in a monotonic A dependence of the L/T-ratio at different values of Q^2. On the contrary, for a coherent process the contraction of the CL with Q^2 causes an effect opposite to that of CT and we expect quite a nontrivial A dependence, especially at Q^2 >> m_V^2.Comment: Revtex 24 pages and 14 figure

CPT Violation and the Nature of Neutrinos

In order to accommodate the neutrino oscillation signals from the solar, atmospheric, and LSND data, a sterile fourth neutrino is generally invoked, though the fits to the data are becoming more and more constrained. However, it has recently been shown that the data can be explained with only three neutrinos, if one invokes CPT violation to allow different masses and mixing angles for neutrinos and antineutrinos. We explore the nature of neutrinos in such CPT-violating scenarios. Majorana neutrino masses are allowed, but in general, there are no longer Majorana neutrinos in the conventional sense. However, CPT-violating models still have interesting consequences for neutrinoless double beta decay. Compared to the usual case, while the larger mass scale (from LSND) may appear, a greater degree of suppression can also occur.Comment: 10 pages, 1 figur

Loop Quantum Cosmology III: Wheeler-DeWitt Operators

In the framework of loop quantum cosmology anomaly free quantizations of the Hamiltonian constraint for Bianchi class A, locally rotationally symmetric and isotropic models are given. Basic ideas of the construction in (non-symmetric) loop quantum gravity can be used, but there are also further inputs because the special structure of symmetric models has to be respected by operators. In particular, the basic building blocks of the homogeneous models are point holonomies rather than holonomies necessitating a new regularization procedure. In this respect, our construction is applicable also for other (non-homogeneous) symmetric models, e.g. the spherically symmetric one.Comment: 19 page