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.
118584962
Real time studies of quantum metastability
18820051
Natural masslessness conservation for neutrinos in two-Higgs-doublet models.
We present a model which supplements the standard electroweak model with three right-handed neutrinos and one extra scalar doublet which does not develop a vacuum expectation value. With the aid of a discrete symmetry the neutrinos are kept strictly massless. This model has several interesting features. It has unsuppressed lepton flavor violating processes, in particular [mu][r arrow][ital e][gamma], hinting at the possibility that these may soon be within experimental reach. The [ital Z] and [ital W] interactions become nondiagonal at one-loop level. In particular, a nontrivial leptonic mixing matrix is seen to arise from the clash between the charged gauge boson and the charged scalar interactions.
117893999
Looking for Delta I = 5/2 amplitude components in B ---> pi pi and B -> rho rho experiments
We discuss how experiments measuring B -> pi pi and B -> rho rho may be used to search for a Delta I = 5/2 amplitude component. This component could be the explanation for a recent (albeit very tentative) hint from B(Bbar) -> rho rho decays that the isospin triangles do not close.
1040688
Constraining new interactions with leptonic tau decays.
The recent measurements of the Michel parameters in {tau} decays enable, for the first time, a thorough analysis of the leptonic sector. In general, in models beyond the standard model, these parameters will be altered through changes in the {ital W} and {ital Z} couplings, and/or through interactions mediated by new gauge bosons. We perform a complete, model-independent analysis of the constraints imposed by the present data on such boson-mediated interactions, and point out the existence of useful relations among the couplings.
10678678
Decoupling or nondecoupling: Is that the R($b$) question?
The top quark is well known for the nondecoupling effects it implies in ρ and Rb. The recent experimental Rb data exhibits a disagreement with the SM prediction at more than the 3σ level. It is tempting to explore whether this might be due to nondecoupling New Physics effects, opposite to those of the top. We investigate this issue in the context of models with an extra family of right or left handed, singlet or doublet quarks. It is shown that, contrary to what
118401678
Searching for Elko dark matter spinors at the CERN LHC
The aim of this paper is to explore the possibility of discovering a fermionic field with mass dimension one, the Elko field, in the Large Hadron Collider. Due to its mass dimension, an Elko can only interact either with Standard Model spinors and gauge fields at one-loop order or at tree level through a quartic interaction with the Higgs field. In this Higgs portal scenario, the Elko is a viable candidate to a dark matter constituent which has been shown to be compatible with relic abundance measurements from WMAP and direct dark matter searches. We propose a search strategy for this dark matter candidate in the channel at the LHC. We show the LHC potential to discover the Elko considering a triple Higgs–Elkos coupling as small as ~0.5 after 1 ab-1 of integrated luminosity. Some phenomenological consequences of this new particle and its collider signatures are also discussed.
124792248
Vortices solutions in Chern-Simons-Maxwell-Higgs system
In this work we analyze some characteristics of Bogomol’nyi ’s equations for abelian gauge theories with Chern-Simons-Maxwell-Higgs terms. We don’t obt ain the complete solution for the model, but we analyze the equations in a kind of weak field appr oximation instead of using a computational analysis. Our main idea is to get some intuition on the subject. Working with the equations in such approach we reproduce the accurate behavior next to the origin.
118653712
Notes on the two-brane model with variable tension
Motivated by possible extensions of the braneworld models with two branes, we investigate some consequences of a variable brane tension, using the well established results on consistency conditions. By a slight modification of the usual stress-tensor used in order to derive the braneworld sum rules, we find some important constraints obeyed by time-dependent brane tensions. In particular, it is shown that the tensions of two Randall-Sundrum\char21{}like branes obeying, at the same time, an E\"otv\"os law, aggravate the fine-tuning problem. Also, it is shown that if the hidden brane tension obeys an E\"otv\"os law, then the visible brane has a mixed behavior allowing a bouncinglike period at early times while it is dominated by an E\"otv\"os law now. To finalize, we discuss some qualitative characteristics, which may arise in the scope of dynamical brane tensions, as anisotropic background and branons production.
118720958
Torsion Effects in Braneworld Scenarios
We present gravitational aspects of braneworld models endowed with torsion terms both in the bulk and on the brane. In order to investigate a conceivable and measurable gravitational effect, arising genuinely from bulk torsion terms, we analyze the variation in the black hole area by the presence of torsion. Furthermore, we extend the well-known results about consistency conditions in a framework that incorporates brane torsion terms. It is shown, in a rough estimate, that the resulting effects are generally suppressed by the internal space volume. This formalism provides manageable models and their possible ramifications into some aspects of gravity in this context, and cognizable corrections and physical effects as well.
56092735
Two-branes with variable tension model and the effective Newtonian constant
It is shown that, in the two brane time variation model framework, if the hidden brane tension varies according to the phenomenological Eoetvoes law, the visible brane tension behavior is such that its time derivative is negative in the past and positive after a specific time of cosmological evolution. This behavior is interpreted in terms of a useful mechanical system analog and its relation with the variation of the Newtonian (effective) gravitational ''constant'' is explored.