17876300
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.
119445110
The Use of early data on $B \to \rho \pi$ decays
This paper reviews the Dalitz plot analysis for the decays $B^0(\bar B^0) \to \rho \pi \to \pi^+ \pi^- \pi^0$. We discuss what can be learned about the ten parameters in this analysis from untagged and from tagged time-integrated data. We find that, with the important exception of the interesting CP violating quantity $\alpha$, the parameters can be determined from this data sample -- and, hence, they can be measured at CLEO as well as at the asymmetric $B$ factories. This suggests that the extraction of $\alpha$ from the time-dependent data sample can be accomplished with a smaller data sample (and, therefore, sooner) than would be required if all ten parameters were to be obtained from that time-dependent data sample alone. We also explore bounds on the shift of the true angle $\alpha$ from the angle measured from charged $\rho$ final states alone. These may be obtained prior to measurements of the parameters describing the neutral $\rho$ channel, which are expected to be small.
14931156
ProbingCPviolation with time integrated decay rates into non-CPeigenstates
Many of the experiments proposed to look for interference CP violation in neutral B mesons concentrate on tagged decay into CP eigenstates. Aleksan, Dunietz, Kayser and Le Diberder have shown that one can also look for interference CP violation using tagged decays into non-CP eigenstates. In all these methods, one must trace the time dependence of the decays. In this article we discuss a new method to search for interference CP violation by using only time integrated rates into non-CP eigenstates. The method hinges on the comparison between the decays of $\Upsilon(4S)$ into $f f$, $\bar{f} \bar{f}$, and $f \bar{f}$, and also uses the rates for $l^+ f$ and $l^- f$. This method does not depend on how the $\Upsilon(4S)$ is produced; provided enough statistics, one can use both symmetric and asymmetric colliders.
118851665
Implications of the Possibility that sin(2 beta) is Small
Recently, the Babar and Belle collaborations have reported their first measurements of the CP-violating asymmetry in B{sub d} {yields} {psi}K{sub S}, and more precise results will follow soon. We discuss what a future evidence for small sin2{beta} could mean, contrasting the usual possibility of new physics in the B{sub d} system, with the interesting alternative that the new physics effects are confined to the kaon system.
119183302
CP properties of symmetry-constrained two-Higgs-doublet models
The two-Higgs-doublet model can be constrained by imposing Higgs-family symmetries and/or generalized CP symmetries. It is known that there are only six independent classes of such symmetry-constrained models. We study the CP properties of all cases in the bilinear formalism. An exact symmetry implies CP conservation. We show that soft breaking of the symmetry can lead to spontaneous CP violation (CPV) in three of the classes.
117683940
Opportunities and Tests for Physics Beyond the Standard Model
119179830
Some remarks on the attractor behaviour in ELKO cosmology
Recent results on the dynamical stability of a system involving the interaction of the ELKO spinor field with standard matter in the universe have been reanalysed, and the conclusion is that such system does not exhibit isolated stable points that could alleviate the cosmic coincidence problem. When a constant parameter δ related to the potential of the ELKO field is introduced in the system however, stable fixed points are found for some specific types of interaction between the ELKO field and matter. Although the parameter δ is related to an unknown potential, in order to satisfy the stability conditions and also that the fixed points are real, the range of the constant parameter δ can be constrained for the present time and the coincidence problem can be alleviated for some specific interactions. Such restriction on the ELKO potential opens possibility to apply the ELKO field as a candidate to dark energy in the universe, and so explain the present phase of acceleration of the universe through the decay of the ELKO field into matter.
118619942
The right-handed sneutrino as thermal dark matter in U(1) extensions of the MSSM
We investigate the parameter space of a supersymmetric model with an extended U(1) gauge symmetry in which the RH sneutrino is a thermal dark matter candidate. In this scenario, annihilation of RH sneutrinos proceeds mainly through Higgs or Z' exchange. We find that sneutrinos in the mass range from 50 GeV to more than 1 TeV can be consistent with both the WMAP limit and the direct detection upper limits. Powerful constraints from new gauge boson searches at the LHC as well as from ΔMs are incorporated. Depending on the choice of the U(1) charge, these scenarios will be further probe by direct dark matter searches as well as by Higgs searches at the LHC.
119652642
Black holes in realistic branes: Black string-like objects?
Abstract A realistic model describing a black string-like object in an expanding Universe is analyzed in the context of the McVittieʼs solution of the Einstein field equations. The bulk metric near the brane is provided analogously to previous solutions for black strings. In particular, we show that at least when the Hubble parameter on the brane is positive, a black string-like object seems to play a fundamental role in the braneworld scenario, generalizing the standard black strings in the context of a dynamical brane.
122201296
ELKO SPINOR FIELDS AS A TOOL FOR PROBING EXOTIC TOPOLOGICAL SPACETIME FEATURES
We report about some achievements and developments provided by the ELKO program, in particular the ones recently accomplished.1 Exotic dark spinor fields has been investigated in the context of inequivalent spin structures on arbitrary curved spacetimes, which induces an additional term on the associated Dirac operator, related to a Cech cohomology class. Exotic terms operating on standard model Dirac spinor fields are usually absorbed by gauge transformations encoded as a shift of some vector potential representing an element of the cohomology group H1(M, ℤ2). That is not the case of ELKO, once they cannot carry gauge charge. As a consequence, the ELKO program requires a complete evaluation of topological analysis. Since exotic dark spinor fields also satisfy Klein-Gordon propagators, the dynamical constraints related to the exotic term in the Dirac equation can be explicitly computed. It forthwith implies that the non-trivial topology associated to the spacetime can drastically engender — from the dynamics of dark spinor fields — constraints on the spacetime metric structure. Besides being candidates to the dark matter problem, dark spinor fields are shown to be potential candidates to probe non-trivial topologies in spacetime, as well as to explain the spacetime metric structure.
119241024
PAMELA and FERMI limits on the neutralino-chargino mass degeneracy
Searches for Dark Matter (DM) particles with indirect detection techniques have reached important milestones with the precise measurements of the anti-proton () and gamma-ray spectra, notably by the PAMELA and FERMI-LAT experiments. While the γ-ray results have been used to test the thermal Dark Matter hypothesis and constrain the Dark Matter annihilation cross section into Standard Model (SM) particles, the anti-proton flux measured by the PAMELA experiment remains relatively unexploited. Here we show that the latter can be used to set a constraint on the neutralino-chargino mass difference. To illustrate our point we use a Supersymmetric model in which the gauginos are light, the sfermions are heavy and the Lightest Supersymmetric Particle (LSP) is the neutralino. In this framework the W+W− production is expected to be significant, thus leading to large and γ-ray fluxes. After determining a generic limit on the Dark Matter pair annihilation cross section into W+W− from the data only, we show that one can constrain scenarios in which the neutralino-chargino mass difference is as large as 20 GeV for a mixed neutralino (and intermediate choices of the propagation scheme). This result is consistent with the limit obtained by using the FERMI-LAT data. As a result, we can safely rule out the pure wino neutralino hypothesis if it is lighter than 450 GeV and constitutes all the Dark Matter.