M. Capdequi Peyranère

Higgs decays in the two Higgs doublet model: Large quantum effects in the decoupling regime

We study the Higgs-boson decays h 0 → b ¯, h 0 → and h 0 → Z within the framework of the Two Higgs Doublet Model (THDM) in the context of the decoupling regime, together with tree level unitarity constraints. We show that when the light CP-even Higgs boson of the THDM mimics the Standard-Model Higgs boson, not only the one-loop effects to h 0 → {, Z} but also the one-loop

Associated H− W+ production in high energy e+e− collisions

Abstract We study the associated production of charged Higgs bosons with W gauge bosons in high energy e + e − collisions at the one loop level. We present the analytical results and give a detailed discussion for the total cross section predicted in the context of a general Two Higgs Doublet Model (THDM).

Is natural fine tuning feasible in the standard model

Abstract A recent proposal for estimating the Higgs and the top masses from a naturalness requirement is reconsidered. We perform a calculation of the overall quadratic divergencies up to two loop order in the standard model, in general linear and non-linear renormalizable gauges R nl (a, b, E 0 , E w ) , and recover the necessary gauge invariance of the mass equations. However, our equations disagree slightly with those derived previously and actually jeopardize the whole procedure. Alternative solutions and open questions are also briefly discussed.

Fermion and sfermion effects in e+ e− charged Higgs pair production☆

Abstract Top and bottom one-loop corrections to e+ e− → H+ H− are considered at NLC energies and found to be significantly large and negative over the full range of tan β. Moreover, loop effects of moderately heavy squarks and sleptons in the minimal supersymmetric extension of the standard model, tend to cancel partly or fully these large corrections, thus providing a useful indirect information about the supersymmetric sector. The overall effect can still range between −25% and +25%, however lies typically around −10% in a wide range of the model parameters.

CP odd Higgs boson production in association with neutral gauge boson in high-energy e+ e- collisions

We study the associated production of a CP-odd Higgs boson A0 with a neutral gauge boson (Z or photon) in high-energy e+e- collisions at the one-loop level in the framework of two Higgs doublet models (THDM). We find that in the small tanβ regime, the top quark loop contribution is enhanced leading to significant cross-sections (about a few fb), while in the large tanβ regime the cross-section does not attain observable rates.

Kowalevski's analysis of the swinging Atwood's machine

We study the Kowalevski expansions near singularities of the swinging Atwoods machine. We show that there is an infinite number of mass ratios M/m where such expansions exist with the maximal number of arbitrary constants. These expansions are of the so-called weak Painleve type. However, in view of these expansions, it is not possible to distinguish between integrable and nonintegrable cases.