We have developed the Monte Carlo simulation program Jewel 1.0 (Jet Evolution With Energy Loss), which interfaces a perturbative final-state parton shower with medium effects occurring in ultra-relativistic heavy-ion collisions. This is done by comparing for each jet fragment the probability of further perturbative splitting with the density-dependent probability of scattering with the medium. A s

We present a new model, based on color rearrangements, which at the same time can describe both hidden and open charm production in B-meson decays. The model is successfully compared to both inclusive decays, such as B→J/ψX and B→DsX, as well as exclusive ones, such as B→J/ψK(*) and B→D(*)D(*)K. It also gives a good description of the momentum distribution of direct J/ψ's, especially in the low-mo

The quark-gluon plasma (QGP) can be explored in relativistic heavy ion collisions by the jet quenching signature, i.e., by the energy loss of a high energy quark or gluon traversing the plasma. We introduce a novel QCD evolution formalism in the leading logarithm approximation, where normal parton radiation is interleaved with scattering on the plasma gluons occuring at a similar time scale. The i

We investigate the effects of an all order QCD resummation of soft gluon emissions for Higgs boson production in association with two hard jets. We consider both the gluon-gluon fusion and weak boson fusion processes and show how to resum a large part of the leading logarithms in the jet veto scale. Our resummation improves on previous analyses which also aim to include the effects of multiple sof

To properly discover a charged Higgs Boson (H) requires its spin and couplings to be determined. We investigate how to utilize t spin correlations to analyze the H couplings in the decay t bH + bτ + ν τ . Within the framework of a general Two-Higgs-Doublet Model, we obtain results on the spin analyzing coefficients for this decay and study in detail its spin phenomenology, focusing on the limi

Higgs boson production in association with a high pT photon at the CERN Large Hadron Collider is analyzed, in the framework of the MSSM model, for the heavier neutral Higgs bosons. The request of an additional photon in the exclusive Higgs boson final state selects b-quark pairs among the possible initial partonic states, since gluon-gluon initial states are not allowed by C-parity conservation. H

We report on detailed Monte Carlo comparisons of selection variables to separate tbH± signal events from the standard model tt background using an iterative discriminant analysis (IDA) method. While kinematic differences exist between the two processes whenever m_{Hpm≠}m_Wpm , the exploration of the spin difference between the charged Higgs and the W± gauge boson becomes crucial in the particularl

We investigate the viability of observing charged Higgs bosons ( H± ) produced in association with W bosons at the CERN large hadron collider, using the leptonic decay H+ → + ν τ and hadronic W decay, within different scenarios of the minimal supersymmetric standard model (MSSM) with both real and complex parameters. Performing a parton level study we show how the irreducible standard model backgr

At the Large Hadron Collider, we prove the feasibility to detect pair production of the lightest CP-even Higgs boson h of Type II 2-Higgs Doublet Models through qq (′) qq (′)hh (vector-boson fusion). We also show that, through the hh 4b decay channel in presence of heavy-flavour tagging, further exploiting forward/backward jet sampling, one has direct access to the λ Hhh triple Higgs coupling - wh

We show that partons traversing a quark-gluon plasma can lose substantial amounts of energy also by scatterings, and not only through medium-induced radiation as mainly considered previously. Results from Monte Carlo simulations of soft interactions of partons, emerging from a hard scattering, through multiple elastic scatterings on gluons in an expanding relativistic plasma show a sizeable jet qu

Charged Higgs boson production in association with a top quark could be the first indication of the existence of Higgs particles. The Tevatron Run-II started data-taking in April 2001 at √s = 1960 GeV and could probe the existence of a charged Higgs boson beyond the current mass limit. We study the pp̄ → tbH± production process with Monte Carlo simulations in HERWIG and PYTHIA, comparing expected

We study the process gg → bb̄H+H- at large tanβ, where it represents the dominant production mode of charged Higgs boson pairs in a Type II 2-Higgs doublet model, including the minimal supersymmetric standard model. The ability to select this signal would in principle enable the measurements of some triple-Higgs couplings, which in turn would help understanding the structure of the extended Higgs

We present a new method for matching the two twin-processes gb → H±t and gg → H±tb in Monte Carlo event generators. The matching is done by defining a double-counting term, which is used to generate events that are subtracted from the sum of these two twin-processes. In this way we get a smooth transition between the collinear region of phase space, which is best described by gb → H ±t, and the ha

The hadronic decays of the τ lepton can be used to determine the effective charge ατ(m τ 2,) for a hypothetical τ lepton with a mass in the range 0

Dressed Gluon Exponentiation (DGE) is used to calculate the thrust and the heavy-jet mass distributions in e + e - annihilation in the two-jet region. We perform a detailed analysis of power corrections, taking care of the effect of hadron masses on the measured observables. In DGE the Sudakov exponent is calculated in a renormalization-scale invariant way using renormalon resummation. Neglecting