arXiv subjects

Ehab Malkawi

Publications and source records attributed to Ehab Malkawi.

16 recordsLinked to original sources

arXiv2015

Fractional Integral and Derivative of the 1/r Potential

We calculate the fractional integral and derivative of the potential $1/r$ for all values of the fractional order $-1< α\leq 0$ and $α\geq 0$. We show that the result has the same form for all values of $α$. Applications can be implemented to discuss deformed potential fields resulting from fractional mass or charge densities in gravity and electrostatics problems. The result can also be applied to modify the inverse-quare law gravity as predicted by new physics.

physics.gen-ph↗

arXiv2015

Spatial Rotation of the Fractional Derivative in Two Dimensional Space

The transformation of the partial fractional derivatives under spatial rotation in $R^2$ are derived for the Riemann-Liouville and Caputo definitions. These transformation properties link the observation of physical quantities, expressed through fractional derivatives, with respect to different coordinate systems (observers). It is the hope that such understanding could shed light on the physical interpretation of fractional derivatives. Also it is necessary to able to construct interaction terms that are invariant with respect to equivalent observers.

math.GM↗

arXiv2013

Transformation Property of the Caputo Fractional Differential Operator in Two Dimensional Space

The transformation property of the Caputo fractional derivative operator of a scalar function under rotation in two dimensional space is derived. The study of the transformation property is essential for the formulation of fractional calculus in multi-dimensional space. The inclusion of fractional calculus in the Lagrangian and Hamiltonian dynamics relies on such transformation. An illustrative example is given.

math-ph↗

arXiv2002

Neutrino Oscillations Due to Nonuniversal Gauge Interactions in the Weak Sector

We discuss the structure of the neutrino mass matrix as derived from a nonuniversal electroweak gauge interaction model. We discuss two interesting patterns of neutrino masses. The first pattern is hierarchal which fits the LMA or LOW solutions of solar neutrino data. The second pattern gives rise to inverted mass spectrum which fits the currently not preferred SMA solution. The mechanism for generating a light sterile neutrino mass is interesting and is briefly discussed.

hep-ph↗

arXiv2000

Boson Condensation in an Einstein Universe

In this paper we investigate the Bose-Einstein condensation of massive spin-1 particles in an Einstein universe. The system is considered under relativistic conditions taking into consideration the possibility of particle-antiparticle pair production. An exact expression for the charge density is obtained, then certain approximations are employed in order to obtain the solutions in closed form. A discussion of the approximations employed in this and other work is given. The effects of finite-size and spin-curvature coupling are emphasized.

gr-qc↗

arXiv2000

A Light Sterile Neutrino in the TopFlavor Model

A scenario based on the TopFlavor model is presented to explain the origin of a light sterile neutrino as indicated by all combined neutrino oscillation experiments. The model is phenomenologically well motivated and compatible with all available low-energy data. The derived nuetrino mass matrix can qualitatively explain the observed hierarchy in the neutrino mass splittings as indicated by the neutrino oscillation data. Numerical results are obtained for special cases.

hep-ph↗

arXiv1999

Common Hierarchical Lepton Mass Textures for Atmospheric and Solar Neutrino Oscillations

We propose and study a common hierarchical mass texture for both charged lepton and neutrino sectors. The texture gives rise to a large $ν_μ\leftrightarrowν_τ$ mixing. Also it leads to the small angle MSW effect solution for solar neutrino data. It naturally gives a small $ν_e\leftrightarrow ν_τ$ oscillation relevant to the CHOOZ result in certain mass limits.

hep-ph↗

arXiv1999

New Physics in the Third Family and its Effect on Low Energy Data

We investigate, in detail, a model in which the third family fermions are subjected to an SU(2) dynamics different from the first two families. Constrained by the precision Z-pole data, the heavy gauge boson mass is bounded from below to be about 1.7 TeV at the $2σ$ level. The flavor-changing neutral current (FCNC) in the lepton sector can be significant in $τ\leftrightarrow e$ and $τ\leftrightarrow μ$ transitions. In the latter case, the ratio $Br(τ\to μ\bar{ν_μ} ν_τ)/ Br(τ\to e \bar{ν_e} ν_τ)$ and $Br(τ\to μμμ)$ can constrain the model better than LEP/SLC data in some region of the parameter space. Furthermore, FCNCs are unavoidable in the quark sector. Significant effects to the $B^0-\bar{B^0}$ mixing and the rare decays of the K and B mesons, such as $K^\pm \to π^\pm ν{\bar ν}$, $b \to s ν{\bar ν}, B_s \to τ^+τ^-, μ^+μ^-$ and $B_{s,d} \to μ^\pm τ^\mp$, are expected.

hep-ph↗

arXiv1998

Low Energy Data and a Model of Flavor Mixing

We consider a model in which the third family fermions are subjected to an SU(2) interaction different from the first two family fermions. Constrained by the Z-pole data, the heavy gauge boson mass is bounded from below to be about 1.7 TeV at the $2σ$ level. In this model, the flavor mixing between $τ$ and $μ$ can be so large that $Br(τ\to μ\bar{ν_μ} ν_τ)/ Br(τ\to e \bar{ν_e} ν_τ)$ and $Br(τ\to μμμ)$ provide a better constraint than the LEP/SLC data in some region of parameter space. Furthermore, flavor-changing neutral currents are unavoidable in the quark sector of the model. Significant effects to the $B^0-\bar{B^0}$ mixing and the rare decays of the $K$ and $B$ mesons, such as $K^\pm \to π^\pm ν{\bar ν}, b \to s ν{\bar ν}, B_s \to τ^+τ^-, μ^+μ^-$ and $B_{s,d} \to μ^\pm τ^\mp$, are expected.

hep-ph↗

arXiv1997

Probing the Electroweak Symmetry Breaking Sector with the Top Quark

A study on the effective anomalous interactions, up to dimension 5, of the top quark with the electroweak gauge bosons is made in the non-linear Chiral Lagrangian approach. Bounds on the anomalous dimension four terms are obtained from their contribution to low energy data. Also, the potential contribution to the production of top quarks at hadron colliders (the Tevatron and the LHC) and the electron Linear Collider from both dimension 4 and 5 operators is analyzed.

hep-ph↗

arXiv1996

Probing the Electroweak Symmetry Breaking Sector with the Top Quark

A study on effective anomalous interactions up to dimension 5 of the top quark with the electroweak gauge bosons is made in the non-linear Chiral Lagrangian approach. Bounds on the anomalous dimension four terms are obtained from their contribution to low energy data. Also, the potential contribution to the production of top quarks at hadron colliders (the Tevatron and the LHC) and the electron Linear Collider from both dimension 4 and 5 operators is analysed.

hep-ph↗

arXiv1996

Top-Charm Strong Flavor-Changing Neutral Currents at the Tevatron

The possibility of an anomalous coupling between the top and charm quarks and the gluon field is explored in a model-independent way using an effective Lagrangian that is gauge-invariant under a non-linear realization of SU(3)$_{C} \times$ SU(2$)_{L} \times$ U(1$)_{Y}$. Even for the current 200 $pb^{-1}$ of integrated luminosity at the Tevatron, the new physics scale that strongly modifies the coupling of t-c-g must be larger than about 2.5 TeV if no signal is found within a 3$σ$ confidence limit. For 1 $fb^{-1}$ of data, this constraint can be pushed up to 3.8 TeV.

hep-ph↗

arXiv1996

A Model of Strong Flavor Dynamics for the Top Quark

We discuss a model in which the third generation fermions undergo a different $SU(2)$ weak interaction from the first two generation fermions. In general, a flavor changing neutral current interaction is expected. Constrained by the precision low energy data, the mass ($M_{Z'}=M_{W'}$) of the heavy gauge bosons is bounded from below to be about $1.1$ TeV for $α_s=0.125$ and about $1.3$ TeV for $α_s=0.115$, at the $3σ$ level. This model favors a larger $R_b$ and a smaller $R_c$ as compared with the Standard Model, but it does not explain the $R_c$ data. If one takes the $R_b$ data seriously, then $M_{Z'}$ is bounded, at the $3σ$ level, to be $462$ GeV $< M_{Z^{\prime}} \cosϕ< 1481\,\, {\rm{GeV}}$, where $\cosϕ$ is the mixing angle between the two $SU(2)$'s in the model. Effects predicted for high energy experiments at the Tevatron, LEP140, LEP-II, LHC, and future linear colliders are also discussed.

hep-ph↗

arXiv1995

Effects of a heavy top quark on low energy data using the electroweak chiral Lagrangian

We study large top quark mass effects on low energy physics in the chiral Lagrangian formulated electroweak theories. We show that these radiative corrections can be easily obtained from a set of Feynman diagrams involving only the scalar Goldstone bosons and the fermions when the contributions of the order $g$ (the weak coupling) are ignored. Using CERN LEP and SLAC Linear Collider (SLC) data we constrain on the nonstandard couplings, which might originate from the spontaneous symmetry-breaking sector, of the top quark to the electroweak gauge bosons.

hep-ph↗

arXiv1994

A Global Analysis of the Top Quark Couplings to Gauge Bosons

We propose to probe the electroweak symmetry breaking sector by measuring the effective couplings of the top quark to gauge bosons. Using precision LEP data, we constrain the non--universal couplings of t-t-Z and t-b-W, parameterized by $κ_{L}^{NC}$, $κ_{R}^{NC}$, $κ_{L}^{CC}$ and $κ_{R}^{CC}$, in the electroweak chiral lagrangian framework. Different scenarios of electroweak symmetry breaking will imply different correlations among these parameters. We found that at the order of ${m_t}^{2}\log Λ^2$, in which $Λ\sim 4 πv$ is the cut--off scale of the effective theory, $κ_{L}^{NC}$ is already constrained by LEP data. In models with an approximate custodial symmetry, a positive $κ_{L}^{CC}$ is preferred. $κ_{L}^{CC}$ can be constrained by studying the direct detection of the top quark at the Tevatron and the LHC. At the NLC, $κ_{L}^{NC}$ and $κ_{R}^{NC}$ can be better measured.

hep-ph↗

arXiv1994

Probing the Couplings of the Top Quark to Gauge Bosons

We parameterize the non-universal couplings of t-t-Z and t-b-W in the electroweak chiral lagrangian approach, and examine the constraints on these parameters from the LEP data. We also study how the SLC, Tevatron, LHC and NLC can improve the measurement of these couplings. Different symmetry breaking scenarios imply different correlations among these couplings, whose measurement will then provide a means to probe the electroweak symmetry breaking sector.

hep-ph↗