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Abdelhamid Albaid

Publications and source records attributed to Abdelhamid Albaid.

5 recordsLinked to original sources
arXiv2025

Relativistic Correction to the Magnetic Moment of the Charged Lepton

We derive a general relativistic Hamiltonian valid for both bound and scattering systems by reducing the four-component Dirac equation to a two-component Dirac-Pauli form. Unlike conventional approaches, our formulation includes first-order relativistic corrections in a compact, gauge-consistent expression applicable to arbitrary electromagnetic fields - including non-uniform and time-dependent configurations. As an application, we compute the O(alpha^2) relativistic correction to the Lande g-factor in hydrogen-like atoms, revealing a novel mj^2-dependent term that generalizes the Breit result. This correction is experimentally testable in Penning trap spectroscopy. We further show that relativistic effects become comparable to QFT corrections in highly charged ions where Z ~ 1/sqrt(alpha)

hep-ph↗
arXiv2015

Strong CP and SUZ$_2$

Solutions to the strong CP problem typically introduce new scales associated with the spontaneous breaking of symmetries. Absent any anthropic argument for small $\barθ$, these scales require stabilization against ultraviolet corrections. Supersymmetry offers a tempting stabilization mechanism, since it can solve the "big" electroweak hierarchy problem at the same time. One family of solutions to strong CP, including generalized parity models, heavy axion models, and heavy $η^\prime$ models, introduces $\mathbb{Z}_2$ copies of (part of) the Standard Model and an associated scale of $\mathbb{Z}_2$-breaking. We review why, without additional structure such as supersymmetry, the $\mathbb{Z}_2$-breaking scale is unacceptably tuned. We then study "SUZ$_2$" models, supersymmetric theories with $\mathbb{Z}_2$ copies of the MSSM. We find that the addition of SUSY typically destroys the $\mathbb{Z}_2$ protection of $\barθ=0$, even at tree level, once SUSY and $\mathbb{Z}_2$ are broken. In theories like supersymmetric completions of the twin Higgs, where $\mathbb{Z}_2$ addresses the little hierarchy problem but not strong CP, two axions can be used to relax $\barθ$.

hep-ph↗
arXiv2011

Flavor Violation in a Minimal SO(10)\times A_4 SUSY GUT

Flavor violating processes in the quark and lepton sectors are investigated within a realistic supersymmetric $SO(10)\times A_4$ grand unification model. By employing exotic heavy fermion fields, this model successfully describes various features of the fermion masses and mixings including large neutrino mixings accompanied by small quark mixings. In this model the flavor violation is induced at GUT scale, at which $A_4$ flavor symmetry is broken, as a consequence of the large mixings of the light fermion fields with these exotic heavy fields. The stringent experimental constraint from $μ\rightarrow eγ$ decay rate necessitates a high degree of degeneracy of the supersymmetry breaking soft scalar masses of the exotic heavy fields and supersymmetric scalar partners of the light fermion fields. The choice of slepton masses of order 1 TeV is found to be consistent with the constraints from branching ratio of $μ\rightarrow eγ$ and with all other flavor changing neutral current processes being sufficiently suppressed.

hep-ph↗
arXiv2009

Fermion Masses and Mixings in a Minimal SO(10)X A_4 SUSY GUT

A SUSY SO(10) $\times A_4$ GUT model is constructed for fermion masses and mixing by introducing a minimal set of low dimensional Higgs representations needed to break the guage symmetry down to $SU(3)_c \times U(1)_{em}$. The hierarchy of fermion masses can be understood in the framework of $A_4$ symmetry. From the $A_4$-invariant superpotential, the "double lopsided" mass matrices for the charged leptons and the down quarks are obtained. It is shown that this structure leads to bi-large neutrino mixings simultaneously with small CKM mixing angles. An excellent fit to the masses and mixings of the quarks and leptons as well as to CP violation parameter is obtained. Moreover, the model predicts the neutrino mixing angle $\sinθ_{13}\approx 0.15$.

hep-ph↗