[en] We illustrate preliminary results obtained through Monte Carlo (HERWIG) and detector (ATLFAST) simulations of the H^± → τ^±ν_τ signature of charged Higgs bosons with masses comparable to that of the top quark

[en] A light Higgs boson with substantial branching ratio into invisible channels can occur in a variety of models with: light neutralinos, spontaneously broken lepton number, radiatively generated neutrino masses, additional singlet scalar(s) and/or right handed neutrinos in the extra dimensions of TeV scale gravity. We study the observability of the WH and ZH modes at LHC with H decaying invisibly, by carrying out a detailed simulation with two event generators (HERWIG and PYTHIA) and realistic detector simulations (GETJET and CMSJET). We find that the signal with 'single lepton plus missing E_T' resulting from WH production suffers from a very large background due to the (off-shell) W^* production via the Drell-Yan process. In contrast, the ZH mode provides a clean signal in the 'dilepton plus missing E_T' channel. By exploiting this second signature, we show that invisible branching ratios of Higgs bosons, BR_inv, larger than ∼0.42 (0.70) can be probed at 5σ level for M_H=120 (160) GeV, respectively, assuming an accumulated luminosity of L=100 fb^-1

[en] The eigenvalue problem for the neutralino mass matrix has been solved exactly and the eigenvalues are expressed in terms of the ν₁/ν₂ chargino and gluino masses which are directly measurable. An analytical formula for the lightest neutralino mass as a function of the above parameters is obtained. Formulae for the photino, zino and neutral higgsino contents of each of the physical neutralino mass eigenstates states have been found. Taking into account these formulae it has been possible to predict the upper (lower) bound on the mass of zino (photino) dominant neutralino states, including the lightest one. The neutralino-gluino and neutralino-chargino mass planes have also been constrained by using the latest LEP data. (orig.)

[en] The possibility of discovering heavy Majorana neutrinos and lepton number violation via the like sign dilepton signal at hadron supercolliders is investigated. The cross-sections for the production of these neutrinos singly as well as in pairs are computed both in three and four generations scenarios within the framework of the gauge group SU(2)_L x U(1)_Y and the dominant processes are identified. The suppression of the Standard model background by suitable kinematical cuts is also discussed. (author)

[en] The like sign dileptons provide the most promising signature for superparticle search in a large category of R-parity-violating SUSY models. We estimate the like sign dilepton signals at the Fermilab Tevatron collider, predicted by these models, over a wide region of the MSSM parameter space. One expects an unambiguous signal up to a gluino mass of 200 endash 300 GeV (≥500 GeV) with the present (proposed) accumulated luminosity of ∼0.1(1) fb^-1. copyright 1996 The American Physical Society

[en] The top quark data in the lepton plus τ channel offers a viable probe for the charged Higgs boson signal. We analyze the recent Collider Detector at Fermilab data in this channel to obtain a significant limit on the H^± mass in the large tanβ region. copyright 1997 The American Physical Society

[en] The allowed regions in the chargino-gluino mass plane are mapped out using the latest Z decay data from experiments. The determination of these masses in future experiments will uniquely fix the neutralino mass spectrum for a fixed υ₁/υ₂. Since the usual two-fold ambiguity is removed by LEP data for gluino masses upto 200 GeV. Constraints have also been placed on neutralino masses. (orig.)

[en] The possibility of discovering heavy Majorana neutrinos and lepton number violation via the like-sign dilepton signal at hadron supercolliders is investigated. The cross sections for the production of these neutrinos singly as well as in pairs are computed both in three- and four-generation scenarios within the framework of the gauge group SU(2)_L direct-product U(1)_Y and the dominant processes are identified. The suppression of the standard model background by suitable kinematical cuts is also discussed

[en] The framework of a warped extra dimension with the Standard Model (SM) fields propagating in it is a very well-motivated extension of the SM since it can address both the Planck-Weak and flavor hierarchy problems of the SM. We consider processes at the large hadron collider (LHC) inspired by signals for new particles in this framework. Our studies include identification of boosted top quarks and W/Z, production of a particle called radion with Higgs-like properties and effects of flavor violating tc Higgs coupling. (authors)

[en] By exploiting the full process pp-bar→tb-barH^-, in place of the standard Monte Carlo procedure of factorising production and decay, pp-bar→tt-bar followed by t-bar→b-barH^-, we show how to improve the discovery reach of the Tevatron (Run 2) in charged Higgs boson searches, in the large tan β region. This is achieved in conjunction with dedicated cuts on a 'transverse mass' distribution sensitive to the Higgs boson mass and to 'polarisation' effects in the H^- →τ^-ν-bar_τ decay channel. (author)