arXiv subjects

Mohamed Chabab

Publications and source records attributed to Mohamed Chabab.

30 records · Page 2Linked to original sources

arXiv2011

Pair production of neutralinos and charginos at the LHC: the role of Higgs bosons exchange

We analyze the effects of the s-channel Higgs bosons exchange on the charginos and neutralinos-pair production in proton-proton collision at the CERN Large Hadron Collider (LHC) in the following channels: $pp \to \Cha^+\Cha^-/\Neu^0\Neu^0 + X$, within the minimal supersymmetric standard model (MSSM). Assuming the usual GUT relation between $M_1$ and $M_2$ at the weak scale, we found that substantial enhancement can be obtained through s-channel Higgs bosons exchange in the mixed regime where $M_2 \sim |μ|$ with moderate to large $\tanβ$ at the resonance of the heavy Higgs bosons. By Combining the phenomenological constraints on neutralinos and charginos, we may still find regions of parameter space where charginos and neutralinos-pair production at the LHC from $b\bar b$ initial state can be large and observable at LHC. We also compute the full complete set of electroweak (EW) contributions to $pp\to gg\to \Cha^+\Cha^-/\Neu^0\Neu^0 + X$ at one loop level in the general MSSM. The analytical computation of the complete tree level amplitude for $b\bar{b} \to \Cha^+\Cha^-/\Neu^0\Neu^0 + X$, including s-channel Higgs exchange, is given.

hep-ph↗

arXiv2010

Lepton Flavour Violating tau and mu decays induced by scalar leptoquark

We show that the scalar leptoquark Yukawa couplings generate a significant lepton flavour violation. We compute the light scalar leptoquark contributions to the branching ratios (Br) of the lepton flavour violating (LFV) decays $\ell \to \ell_i \ell_j \bar{\ell}_j$ and $\ell \rightarrow \ell^{\prime} γ$ with (i,j = e,$μ$). We discuss the role of the relevant input parameters to these decay rates which are the Yukawa couplings ($h_{a\ell}$) with ($a=u,c,t$), the light scalar mass $M_{S_{1}}$ and the mixing angle $\sin2θ_{LQ}$. We investigate the experimental limits from $(g-2)_μ$, $μ-e$ conversion and $π\to e ν_e, μν_μ$ to get constraint on the input parameter space. We predict that the upper limits on the branching ratios of $τ\to \ell_i \ell_j \bar{\ell}_j $ can reach the experimental current limits. We also show that it is possible to accommodate both $τ\to \ell_i \ell_j \bar{\ell}_j$ and $τ\to \ellγ$ branching ratios for certain choices of LQ parameters.

hep-ph↗

arXiv2007

H-> WZ and H->Wgamma in the MSSM

We study the complete one loop contribution to $H^\pm\to W^\pm Z$ and $H^\pm \to W^\pm γ$ in the Minimal Supersymmetric Standard Model (MSSM).

hep-ph↗

arXiv2007

On the implications of a dilaton in gauge theory

Some recent work on the implications of a dilaton in 4d gauge theories are revisited. In part I of this paper we see how an effective dilaton coupling to gauge kinetic term provides a simple attractive mechanism to generate confinement. In particular, we put emphasis on the derivation of confining analytical solutions and look into the problem how dilaton degrees of freedom modify Coulom potential and when a confining phase occurs. In part II, we solve the semi-relativistic wave equation, for Dick interquark potential using the Shifted l-expansion technique (SLET) in the heavy quarkonium sector. The results of this phenomenological analysis proves that these effective theories can be relevant to model quark confinement and may shed some light on confinement mechanism.

hep-ph↗

arXiv2007

CP violation in Charged Higgs Bosons decays $H^\pm \to W^\pm (γ, Z)$ in the Minimal Supersymmetric Standard Model (MSSM)

One loop mediated charged Higgs bosons decays $H^\pm\to W^\pm V$, $V= Z, γ$ are studied in the Minimal Supersymmetric Standard Model (MSSM) with and without CP violating phases. We evaluate the MSSM contributions to these processes taking into account $B\to X_sγ$ constraint as well as experimental constraints on the MSSM parameters. In the MSSM, we found that in the intermediate range of $\tanβ\la 10$ and for large A_t and large $μ$, where the lightest top squark becomes very light and hence non-decoupled, the branching ratio of $H^\pm \to W^{\pm} Z$ can be of the order 10^{-3} while the branching ratio of $H^\pm \to W^{\pm} γ$ is of the order 10^{-5}. We found also that the CP violating phases of soft SUSY parameters can modify the branching ratio by about one order of magnitude. We also show that MSSM with CP violating phases lead to CP-violating asymmetry in the decays $H^+ \to W^+V$ and $H^- \to W^-V$. Such CP asymmetry can be rather large and can reach 80% in some region of parameter space.

hep-ph↗

arXiv2007

Left-Right squarks mixings effects in Charged Higgs Bosons decays $H^\pm \to W^\pm (γ, Z)$ in the MSSM

We study the complete one loop contribution to $H^\pm\to W^\pm V$, $V= Z, γ$, in the Minimal Supersymmetric Standard Model (MSSM). We evaluate the MSSM contributions taking into account $B\to X_sγ$ constraint as well as experimental constraints on the MSSM parameters. In the MSSM, we found that in the intermediate range of $\tanβ\la 10$ and for large $A_t$ and large $μ$, where lightest stop becomes very light and hence squarks contribution is not decoupling, the branching ratio of $H^\pm \to W^{\pm} Z$ can be of the order $10^{-3}$ while the branching ratio of $H^\pm \to W^{\pm} γ$ is of the order $10^{-5}$. We also study the effects of the CP violating phases of Soft SUSY parameters and found that they can modify the branching ratio by about one order of magnitude.

hep-ph↗

arXiv2006

Confinement Driven by Scalar Field in 4d Non Abelian Gauge Theories

We review some of the most recent work on confinement in 4d gauge theories with a massive scalar field (dilaton). Emphasis is put on the derivation of confining analytical solutions to the Coulomb problem versus dilaton effective couplings to gauge terms. It is shown that these effective theories can be relevant to model quark confinement and may shed some light on confinement mechanism. Moreover, the study in the heavy meson sector of an interquark potential derived from Dick Model, proves that phenomenological investigation of this mechanism is more than justified and deserves more efforts.

hep-ph↗

arXiv2006

Charged Higgs Bosons decays H^\pm \to W^\pm (γ, Z) revisited

We study the complete one loop contribution to H^\pm\to W^\pm V, V= Z, γ, both in the Minimal Supersymmetric Standard Model (MSSM) and in the Two Higgs Doublet Model (2HDM). We evaluate the MSSM contributions and compare them with the 2HDM ones taking into account b\to sγconstraint, vacuum stability and unitarity constraints in the case of 2HDM, as well as experimental constraints on the MSSM and 2HDM parameters. In the MSSM, we found that in the intermediate range of \tanβ\la 10 and for large A_t, the branching ratio of H^\pm \to W^{\pm} Z can be of the order 10^{-3} while the branching ratio of H^\pm \to W^{\pm} γis of the order 10^{-5}. We also study the effects of the CP violating phases of Soft SUSY parameters and found that they can modify the branching ratio by about one order of magnitude. However, in the 2HDM where the Higgs sector is less constrained as compared to the MSSM higgs sector, one can reach branching ratio of the order 10^{-2} for both modes.

hep-ph↗

arXiv2005

Confining interquark potentials from nonabelian gauge theories coupled to dilaton

Following a recently proposed confinement generating mechanism, we provide a new string inspired model with a massive dilaton and a new dilaton coupling function [5]. By solving analytically the equations of motion, a new class of confining interquark potentials is derived which includes several popular potential forms given in the literature.

hep-th↗

arXiv2003

Strong CP problem, Neutron EDM and Thermal QCD sum rules

The behaviour of the broken CP symmetry at finite temperature is examined. This is achieved through the investigation of the neutron electric dipole moment $d_n$ induced by $θ$-term. By using thermal QCD sum rules, we find that below the critical temperature, the ratio $\mid {d_n \over \barθ}\mid$ slightly decreases but survives at temperature effects. This evolution implies that CP remains broken at finite temperature as required by Baryogenesis \cite{Chabab}.

hep-ph↗

arXiv2003

Confinement in SU(N_c) gauge theory with a massive dilaton

Following a recently proposed confinement generating scenario \cite{Di}, we provide a new string inspired model with a massive dilaton and a general dilaton-gluon coupling. By solving analytically the equations of motion, we derive a new class of confining interquark potentials, which includes most of the QCD motivated potential forms given in the literature.

hep-th↗

arXiv2002

Theta Term in QCD sum rules at Finite Temperature and the Neutron Electric Dipole Moment

By using thermal QCD sum rules to investigate the $\barθ$ induced neutron electric dipole moment $d_n$, we have examined the behaviour of broken CP symmetry at finite temperature. We find that, below the critical temperature, the ratio $\mid {d_n \over \barθ}\mid$ slightly decreases but survives at temperature effects, implying T nonrestoration of CP-invariance \cite{Chabab}.

hep-ph↗