arXiv subjects

Fawzi Boudjema

Publications and source records attributed to Fawzi Boudjema.

24 records · Page 2Linked to original sources

arXiv2008

b anti-b Higgs production at the LHC: Yukawa corrections and the leading Landau singularity

At tree-level Higgs production in association with a b-quark pair proceeds through the small Yukawa bottom coupling in the Standard Model. Even in the limit where this coupling vanishes, electroweak one-loop effects, through the top-Higgs Yukawa coupling in particular, can still trigger this reaction. This contribution is small for Higgs masses around 120GeV but it quickly picks up for higher Higgs masses especially because the one-loop amplitude develops a leading Landau singularity and new thresholds open up. These effects can be viewed as the production of a pair of top quarks which rescatter to give rise to Higgs production through WW fusion. We study the leading Landau singularity in detail. Since this singularity is not integrable when the one-loop amplitude is squared, we regulate the cross section by taking into account the width of the internal top and W particles. This requires that we extend the usual box one-loop function to the case of imaginary masses. We show how this can be implemented analytically in our case. We study in some detail the cross section at the LHC as a function of the Higgs mass and show how some distributions can be drastically affected compared to the tree-level result.

hep-ph↗

arXiv2007

Leading Yukawa corrections to Higgs production associated with a tagged bottom anti-bottom pair in the Standard Model at the LHC

Considering the large value of the top Yukawa coupling, we investigate the leading one-loop Yukawa electroweak corrections that can be induced by the top quark in a process such as Higgs production in association with a tagged bottom anti-bottom pair at the LHC. At NLO these contributions are found to be small at the LHC both for the total cross section and for the distributions. In the limit of vanishing bottom Yukawa coupling where the LO contribution vanishes, the process can still be induced at one-loop through the top quark transition. Though this contribution which can be counted as part of the NNLO correction is small for Higgs masses around 120GeV, it quickly picks up for higher Higgs masses. This contribution represents the rescattering of the top quarks and their decay into W's leading to Higgs production through WW fusion

hep-ph↗

arXiv2001

Physics for the future colliders

Physics issues at the upcoming and planned colliders are discussed. We critically review the the different arguments that suggest that New Physics is bound to materialise at the TeV scale and why we should keep an open minded approach. The complementarity of the LHC and a moderate energy e+ e- collider is stressed together with the need for higher energy machines.

hep-ph↗

arXiv1998

Physics at the Linear Collider

The physics at the planned $e^+e^-$ colliders is discussed around three main topics corresponding to different manifestations of symmetry breaking: $W$ physics in the no Higgs scenario, studies of the properties of the Higgs and precision tests of SUSY. A comparison with the LHC is made for all these cases. The $γγ$ mode of the linear collider will also be reviewed.

hep-ph↗

arXiv1995

Physics of Self-Interacting Electroweak Bosons

I will argue why and how it is that precise measurements of the self-couplings of the weak vector bosons are a vista on the mechanism of symmetry breaking. Guided by what we have learnt from the present precision data, it is suggested which of the many so-called anomalous self-couplings should be given priority in future searches. Expected limits from the upcoming colliders on the parameters describing non minimal couplings are updated. I will also point at the complementarity between the LHC and the Next Linear Collider as concerns $W$ physics and discuss some of the important issues about radiative corrections and backgrounds that need further studies in order that one conducts high precision analysis at high energies.

hep-ph↗

arXiv1993

Tests on the Hierarchy of Trilinear and Quadrilinear Weak Bosons Couplings at the NLC and Comparison with the LHC/SSC

I first review a few basic guiding principles that lead to the notion of a hierarchy of couplings in searches of New Physics involving weak bosons processes. The hierarchies within a linear and a non-linear realization of symmetry breaking are compared to the usual {\em phenomenological} parameterization of the $WWV$ vertex. Limits that one expects to obtain at the NLC(500GeV) and LHC/SSC on the tri-linear and quadri-linear anomalous $W$ couplings are compared. The cleanness of an \epm gives the NLC a clear advantage in constraining the tri-linear couplings. However, with ``only" $500$GeV, the \epm is not competitive with $pp$ colliders in probing the quadri-linear couplings. An interpretation in terms of scalar-like and vector-like models is given and I argue that in the presence of a light (or ``not-so-heavy") Higgs, the New Physics affecting the $W$ sector would be easier to pin-down with a moderate energy \epm machine.

hep-ph↗