B->rho pi decays, resonant and nonresonant contributions

We point out that a new contribution to B decays to three pions is relevant in explaining recent data from the CLEO and BABAR collaborations, in particular the results on quasi-two-body decays via a rho meson. We also discuss the relevance of these contribution to the measurement of CP violations.Comment: 5 pages, 2 figures, few references and minor comments adde

Production and decay of gluino pairs at hadron colliders

At hadron colliders, one of the most important channels for sparticle production is expected to be the gluino pair production. In the scenario where the sbottom is lighter than the gluino, gluinos can decay into sbottom and bottom quarks. Sbottoms can subsequently decay into bottom quarks and neutralinos. Hence, one expects a rich signature consisting of four b-jets and the missing transverse energy from neutralinos. To compute the cross section of this reaction, it is important to find tools and techniques suitable for the calculation of diagrams with many particles in the final state. We present here a way to deal with such complicated reactions.Comment: Proceedings of the Conference: "QCD and High Energy Hadronic Interactions", XXXXth Rencontres de Moriond, La Thuile, Italy - March 12-19, 2005 - 4 pages. References update

ATLAS discovery potential for a heavy charged Higgs boson

The sensitivity of the ATLAS detector to the discovery of a heavy charged Higgs boson is presented. Assuming a heavy SUSY spectrum, the most promising channels above the top quark mass are $H^\pm\to tb$ and $H^\pm\to\tau^\pm\nu_\tau$ which provide coverage in the low and high $\tan\beta$ regions up to $\sim 600$ GeV. The achievable precisions on the charged Higgs mass and $\tan\beta$ determination are also discussed. The $H^\pm\to W^\pm h^0$ channel, though restricted to a small MSSM parameter space, shows a viable signal in NMSSM where the parameter space is less constrained. The observation of the channel $H^-\to\tau^-_L\nu_\tau + c.c.$ may constitute a distinctive evidence for models with singlet neutrinos in large extra dimensions.Comment: 18 page

On the mass of the Ds(0+,1+) system

In this note we discuss a determination for the mass of the Ds(0+,1+) system recently discovered by the BaBar, CLEO II and Belle Collaborations. The value of the mass is derived by making explicit the prediction obtained in a quark-meson model prior to the discovery of these states.Comment: 3 pages, revte

The exclusive B_s -> phi mu+ mu- process in a constituent quark model

We consider the exclusive B_s -> phi mu+ mu- process in the standard model using a constituent quark loop model approach together with a simple parameterization of the quark dynamics. The model allows to compute the decay form factors and therefore can give predictions for the decay rates, the invariant mass spectra and the asymmetries. This process is suppressed in the standard model but can be enhanced if new physics beyond the standard model is present, such as flavor-violating supersymmetric models. It constitutes therefore an interesting precision test of the standard model at forthcoming experiments.Comment: 17 pages, 6 figures, 5 tables, LaTeX; minor changes to the introduction, table III and figure 3. Few references adde

Higgs couplings parameterisations

The discovery of a Higgs boson at the Large Hadron Collider (LHC) has provided a proof of the structure for the spontaneous breaking of the electroweak interactions, described as a gauge theory, in its simplest and most concise form. However this simple description in terms of a single complex scalar doublet giving rise to the masses of the weak gauge bosons and to a physical scalar Brout-Englert-Higgs boson demands closer scrutiny, both for the detailed properties of the boson couplings with respect to the values expected from the Standard Model (SM) and with respect to the existence of other scalar states. Indeed extensions of the SM built to answer more detailed questions about the weak interactions and beyond, typically require either an extended scalar sector or a composite nature for the Higgs boson, or both. These detailed analyses can be performed at different levels, going from simple coupling-based descriptions inspired from the experimental measurements of the Higgs boson properties, to effective Lagrangian descriptions, to studies performed in specific models. In any case no description is completely general as a set of assumptions are required as starting points for its validity. Instead of selecting specific models I will mainly discuss in the following a coupling-based description, both for a single physical neutral scalar field and for two neutral scalar fields, as this is relevant in various extensions of the SM