Variations on a Higgs theme

We show how the $Z$ boson can be generated in gluon-gluon fusion and yield two photons, via $gg\to Z\to \gamma\gamma$, through massive fermion loops only, thereby contributing events to a candidate Higgs sample in the di-photon channel. A sub-leading contribution also exists from $q\bar q\to Z\to\gamma\gamma$ events. Assuming the Standard Model, the corresponding event rates are negligible at the LHC stages of 7, 8 TeV, given the luminosities collected therein (about 5 and 20 fb$^{-1}$, respectively). Conversely, at 14 TeV, the first process become accessible for luminosities of order 300 fb$^{-1}$. Finally, we show how additional fermion states entering such loops, in production, in decay or in both cases, could affect the predictions in this channel by curiously mimicking Higgs signals.Comment: 18 pages, 1 table, 4 figure

HERWIG: an event generator for e+e−e^+e^- Linear Colliders

I review all the new features of the HERWIG event generator which are relevant to Linear Collider (LC) physics starting from version 6.1Comment: 9 pages, latex, 4 figures; talk given at the International Workshop on Linear Colliders (LCWS2002), Jeju Island, Korea, 26-30 August 200

Double Higgs peak in the minimal SUSY B-L model

Motivated by a $\sim 3\sigma$ excess recorded by the CMS experiment at the LHC around a mass of order $\sim 137$ GeV in $ZZ\to 4l$ and $\gamma\gamma$ samples, we analyse the discovery potential of a second neutral Higgs boson in the Supersymmetric $B-L$ extension of the Standard Model (BLSSM) at the CERN machine. We confirm that a double Higgs peak structure can be generated in this framework, with CP-even Higgs boson masses at $\sim125$ GeV and $\sim137$ GeV, unlike the case of the Minimal Supersymmetric Standard Model (MSSM).Comment: 7 pages, 4 figures. Improved discussion of experimental dat

Higgs Sector of Non-minimal Supersymmetric Models at Future Hadron Colliders

We investigate the potential of current and planned hadron colliders operating at the TeV scale in disentangling the structure of the Higgs sector of non-minimal Supersymmetric extensions of the Standard Model with an extra gauge singlet. We assume universality of the soft Supersymmetry breaking terms at the GUT scale as well as a CP-even Higgs boson with mass around 115 GeV, as suggested by LEP. We find that mixing angles between the doublet and singlet Higgs states are always small. However, concrete prospects exist at both the Tevatron (Run II) and the Large Hadron Collider of detecting at least one neutral Higgs state with a dominant singlet component, in addition to those available from a doublet Higgs sector which is similar to the one of the Minimal Supersymmetric Standard Model.Comment: 4 pages, 2 figures, latex, contribution to the APS/DPF/DPB Summer Study on the `Future of Particle Physics (Snowmass 2001)', Snowmass, Colorado, 30 June - 21 July 200

Higgs boson decays into {\gamma}{\gamma} and Z{\gamma} in the MSSM and BLSSM

We calculate Higgs decay rates into {\gamma}{\gamma} and Z{\gamma} in the Minimal Supersymmetric Standard Model (MSSM) and (B-L) Supersymmetric Standard Model (BLSSM) by allowing for contributions from light staus and charginos. We show that sizable departures are possible from the SM predictions for the 125 GeV state and that they are testable during run 2 at the Large Hadron Collider. Furthermore, we illustrate how a second light scalar Higgs signal in either or both these decay modes can be accessed at the CERN machine rather promptly within the BLSSM, a possibility instead precluded to the MSSM owing to the much larger mass of its heavy scalar state.Comment: Plots slightly modified, no significant chang

Detection of heavy charged Higgs bosons at future Linear Colliders via τ−νˉτH+\tau^-\bar\nu_\tau H^+ production

We show how a statistically significant signal of heavy charged Higgs bosons of a Type II Two-Higgs Doublet (2HDM) Model produced in association with tau-neutrino pairs can be established at future $e^+e^-$ Linear Colliders (LCs) in the $H^+\to t\bar b\to 4$ jet decay channel for large $\tan\beta$ in the M_{H^\pm}\gsim \sqrt s/2 mass regionComment: 6 pages, latex, 3 figures; talk given at the International Workshop on Linear Colliders (LCWS2002), Jeju Island, Korea, 26-30 August 2002; one reference added and one correcte

HERWIG: an event generator for MSSM processes

The HERWIG event generator was widely used throughout the workshop, particularly in the emulation of Supersymmetric and Higgs processes in the context of the Minimal Supersymmetric Standard Model. We briefly review here its main features in this respectComment: 5 pages, no figures, talk given at the `Seventh Workshop on High Energy Physics Phenomenology WHEPP-VII', Harish Chandra Research Institute, Allahabad, India, 4-15 January 2002 (to be published by PRAMANA - Journal of Physics