T. Ibrahim - Alexandria University & Northeastern University

T. Ibrahim
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Name
T. Ibrahim
Affiliation
Alexandria University & Northeastern University
City
Boston
Country
United States

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High Energy Physics - Phenomenology (47)
 
High Energy Physics - Experiment (11)
 
Quantum Physics (2)
 
High Energy Physics - Theory (1)
 
Nuclear Experiment (1)
 
Nuclear Theory (1)
 
Mathematics - Mathematical Physics (1)
 
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Mathematical Physics (1)

Publications Authored By T. Ibrahim

In the standard model flavor violating decays of the top quark and of the Higgs boson are highly suppressed. Further, the flavor violating decays of the top and of the Higgs are also small in MSSM and not observable in current or in near future experiment. In this work we show that much larger branching ratios for these decays can be achieved in an extended MSSM model with an additional vector like quark generation. Read More

Recent data from the ATLAS and CMS detectors at the Large Hadron Collider at CERN give a hint of possible violation of flavor in the leptonic decays of the Higgs boson. In this work we analyze the flavor violating leptonic decays $H^0_1\to l_i \bar l_j$ ($i\neq j$) within the framework of an MSSM extension with a vectorlike leptonic generation. Specifically we focus on the decay mode $H^0_1\to \mu\tau$. Read More

Higgs boson mass measurement at $\sim 125$ GeV points to a high scale for SUSY specifically the scalar masses. If all the scalars are heavy, supersymmetric contribution to the leptonic $g-2$ moments will be significantly reduced. On the other hand the Brookhaven experiment indicates a 3sigma deviation from the standard model prediction. Read More

One loop contributions to the CP even-CP odd Higgs boson mixings arising from contributions due to exchange of a vectorlike multiplet are computed under the Higgs boson mass constraint. The vectorlike multiplet consists of a fourth generation of quarks and a mirror generation. This sector brings in new CP phases which can be large consistent with EDM constraints. Read More

An analysis is given of the chromoelectric dipole moment of quarks and of the neutron in an MSSM extension where the matter sector contains an extra vectorlike generation of quarks and mirror quarks. The analysis includes contributions to the CEDM from the exchange of the $W$ and the $Z$ bosons, from the exchange of charginos and neutralinos and the gluino. Their contribution to the EDM of quarks is investigated. Read More

The experimental limit on the neutron electric dipole moment is used as a possible probe of new physics beyond the standard model. Within MSSM we use the current experimental limit on the neutron EDM and possible future improvement as a probe of high scale SUSY. Quantitative analyses show that scalar masses as large as a PeV and larger could be probed in improved experiment far above the scales accessible at future colliders. Read More

An analysis is given of the decay $\mu \to e+ \gamma$ in an MSSM extension with a vectorlike generation. Here mixing with the mirrors allows the possibility of this decay. The analysis is done at the one loop level with the exchange of charginos and neutralinos and of sleptons and mirror sleptons in the loops. Read More

We give a quantitative analysis of the electric dipole moments as a probe of high scale physics. We focus on the electric dipole moment of the electron since the limit on it is the most stringent. Further, theoretical computations of it are free of QCD uncertainties. Read More

The anomalous magnetic moment of the electron is determined experimentally with an accuracy of $2.8\times 10^{-13}$ and the uncertainty may decrease by an order of magnitude in the future. While the current data is in excellent agreement with the standard model, the possible future improvement in the error in $\Delta a_e= a_e^{\text{exp}}- a_e^{\text{theory}}$ has recently drawn interest in the electron anomalous magnetic moment as a possible probe of new physics beyond the standard model. Read More

An analysis of the Dirac neutrino magnetic moment with standard model interactions gives $\mu_\nu\sim 3 \times 10^{-19} \mu_B (m_\nu/1 eV)$. The observation of a significantly larger magnetic moment will provide a clear signal of new physics beyond the standard model. The current experimental limits on the neutrino magnetic moments are orders of magnitude larger than the prediction with the standard model interactions and thus its test appears out of reach. Read More

An analysis of radiative decays of the neutrinos $\nu_j\to \nu_l \gamma$ is discussed in MSSM extensions with a vector like lepton generation. Specifically we compute neutrino decays arising from the exchange of charginos and charged sleptons where the photon is emitted by the charged particle in the loop. It is shown that while the lifetime of the neutrino decay in the Standard Model is $\sim 10^{43}$ yrs for a neutrino mass of 50 meV, the current lower limit from experiment from the analysis of the Cosmic Infrared Background is $\sim 10^{12}$ yrs and thus beyond the reach of experiment in the foreseeable future. Read More

An analysis is given of the decay $\tau \to \mu+ \gamma$ in MSSM extensions with a vector like generation. Here mixing with the mirrors allows the possibility of this decay. The analysis is done at one loop with the exchange of charginos and neutralinos and of sleptons and mirror sleptons in the loops. Read More

Using the asymptotic iteration method (AIM), we have obtained analytical approximations to the $\ell$-wave solutions of the Schr\"{o}dinger equation with the Manning-Rosen potential. The equation of energy eigenvalues equation and the corresponding wavefunctions have been obtained explicitly. Three different Pekeris-type approximation schemes have been used to deal with the centrifugal term. Read More

Excited states of $^{80}$Br have been investigated via the $^{76}$Ge($^{11}$B, $\alpha$3n) and $^{76}$Ge($^{7}$Li, 3n) reactions and a new $\Delta I$ = 1 band has been identified which resides $\sim$ 400 keV above the yrast band. Based on the experimental results and their comparison with the triaxial particle rotor model calculated ones, a chiral character of the two bands within the $\pi g_{9/2}\otimes \nu g_{9/2}$ configuration is proposed, which provides the first evidence for chirality in the $A\sim80$ region. Read More

The chromoelectric dipole moment of the top quark is calculated in a model with a vector like multiplet which mixes with the third generation in an extension of the MSSM. Such mixings allow for new CP violating phases. Including these new CP phases, the chromoelectric dipole moment that generates an electric dipole of the top in this class of models is computed. Read More

In this study, we solve the Klein-Gordon equation with equal scalar and vector q-deformed hyperbolic modified P\"{o}schl-Teller potential. The explicit expressions of bound state spectra and the normalized eigenfunctions for s-wave bound states are obtained analytically. The energy equations and the corresponding wave functions for the special cases of the equally mixed q-deformed hyperbolic modified P\"{o}schl-Teller potential for spinless particle are briefly discussed. Read More

The electric dipole moment (EDM) of the top quark is calculated in a model with a vector like multiplet which mixes with the third generation in an extension of the MSSM. Such mixings allow for new CP violating phases. Including these new CP phases, the EDM of the top in this class of models is computed. Read More

The Large Hadron Collider presents an unprecedented opportunity to probe the realm of new physics in the TeV region and shed light on some of the core unresolved issues of particle physics. These include the nature of electroweak symmetry breaking, the origin of mass, the possible constituent of cold dark matter, new sources of CP violation needed to explain the baryon excess in the universe, the possible existence of extra gauge groups and extra matter, and importantly the path Nature chooses to resolve the hierarchy problem - is it supersymmetry or extra dimensions. Many models of new physics beyond the standard model contain a hidden sector which can be probed at the LHC. Read More

It is shown that the electric dipole moment of the tau lepton several orders of magnitude larger than predicted by the standard model can be generated from mixings in models with vector like mutiplets. The EDM of the tau lepton arises from loops involving the exchange of the W, the charginos, the neutralinos, the sleptons, the mirror leptons, and the mirror sleptons. The EDM of the Dirac tau neutrino is also computed from loops involving the exhange of the W, the charginos, the mirror leptons and mirror sleptons. Read More

The possibility that mirror matter with masses in the several hundred GeV- TeV range exists is explored. Mirror matter appears quite naturally in many unified models of particle interactions both in GUTs and in strings often in vector-like combinations. Some of these vector-like multiplets could escape acquiring super heavy masses and remain light down to the low energies where they acquire vector-like masses of electroweak size. Read More

Recent analyses have shown that a sequential fourth generation can be consistent with precision electroweak data. We consider the possibility that the new generation could be a mirror generation with $V+A$ rather than $V-A$ interactions. Specifically we consider an extension of the minimal supersymmetric standard model with a light mirror generation (mirMSSM) . Read More

We compute the one loop corrected effective Lagrangian for the neutralino-neutralino-neutral Higgs interactions $\chi^{0}_{\ell} \chi^{0}_kH^{0}_m$. The analysis completes the previous analyses where similar corrections were computed for the $\bar{f} f H^{0}_m$ couplings, where $f$ stands for Standard Model quarks and leptons and for the chargino-chargino-neutral Higgs couplings $\chi^{+}_l \chi^{-}_kH^{0}_m$ within the minimal supersymmetric standard model MSSM. The effective one loop Lagrangian is then applied to the computation of the neutral Higgs decays. Read More

A review of CP violation from the Standard Model to strings is given which includes a broad landscape of particle physics models, encompassing the non-supersymmetric 4D extensions of the standard model, and models based on supersymmetry, on extra dimensions, on strings and on branes. The supersymmetric models discussed include complex mSUGRA and its extensions, while the models based on extra dimensions include 5D models including models based on warped geometry. CP violation beyond the standard model is central to achieving the desired amount of baryon asymmetry in the universe via baryogenesis and leptogenesis. Read More

We extend previous analyses of the supersymmetric loop correction to the neutral Higgs couplings to include the coupling $\chi^{+}_j \chi^{-}_kH^{0}_l$. The analysis completes the previous analyses where similar corrections were computed for the $\bar{\tau} \tau H^{0}_l$, $\bar{b} b H^{0}_l$, $\bar{c} c H^{0}_l$ and for $\bar{t} t H^{0}_l$ couplings within the minimal supersymmetric standard model. The effective one loop Lagrangian is then applied to the computation of the neutral Higgs decays. Read More

An improved analysis of the $b\to s+\gamma$ decay in the minimal flavor violating case is given taking into account additional contributions in the supersymmetric sector which enter in the next-to-leading-order (NLO) and are enhanced by $\tan\beta$ factors. Specifically, we compute a set of twenty one-loop diagrams to give the most complete analysis to date of the NLO supersymmetric corrections. These modifications are computed from the effective charged Higgs and neutral Higgs couplings involving twelve loop diagrams for the charged Higgs sector and eight loop diagrams for the neutral Higgs sector. Read More

The compatibility of producing the observed amount of dark matter, as indicated by the WMAP data, through the relic abundance of neutralinos with Yukawa unification and with the measured rate of $b\to s \gamma$ is analyzed in mSUGRA and extended SUGRA unified models with the inclusion of CP phases. The CP phases affect the analysis in several ways, e.g. Read More

The one loop corrected effective Lagrangian for the quark-squark-chargino and quark-squark-neutralino interactions is computed. The effective Lagrangian takes into account the loop corrections arising from the exchange of the gluinos, charginos, neutralinos, W, Z, the charged Higgs, and the neutral Higgs. We further analyze the squark decays into charginos and neutralinos and discuss the effect of the loop corrections on them. Read More

The effective Lagrangian including one loop corrections is deduced for the couplings of the charged Higgs with quarks and leptons, and with charginos and neutralinos. The effect of the one loop corrections is found to be quite significant in a number of sectors. The effective Lagrangian is then used to analyze the decay of the charged Higgs into a number of decay channels. Read More

2004Oct
Affiliations: 1Huelva U., 2Alexandria U. & Northeastern U., 3Northeastern U., 4Lisbon, IST

We extend the commonly used mSUGRA framework to allow complex soft terms. We show how these phases can induce large changes of the SUSY threshold corrections to the b quark mass and affect the neutralino relic density predictions of the model. We present some specific models with large SUSY phases which can accommodate the fermion electric dipole moment constraints and a neutralino relic density within the WMAP bounds. Read More

We extend previous analyses of the supersymmetric loop correction to the charged Higgs couplings to include the coupling $H^{\pm}\chi^{\mp}\chi^0$. The analysis completes the previous analyses where similar corrections were computed for $H^+\bar t b$ ($H^-t\bar b$), and for $H^+\tau^- \bar\nu_{\tau}$ ($H^- \tau^+ \nu_{\tau}$) couplings within the minimal supersymmetric standard model. The effective one loop Lagrangian is then applied to the computation of the charged Higgs decays. Read More

An analysis of the sensitivity of supersymmetric dark matter to variations in the b quark mass is given. Specifically we study the effects on the neutralino relic abundance from supersymmetric loop corrections to the mass of the b quark. It is known that these loop corrections can become significant for large $\tan\beta$. Read More

Supersymmetric QCD and supersymmetric electroweak loop corrections to the violations of weak isospin to Yukawa couplings are investigated. Specifically it involves an analysis of the supersymmetric loop corrections to the Higgs couplings to the third generation quarks and leptons. Here we analyze the SUSY loop corrections to the charged Higgs couplings which are then compared with the supersymmetric loop corrections to the neutral Higgs couplings previously computed. Read More

A brief review is given of recent analyses of the effects of CP phases on the supersymmetric QCD and supersymmetric electroweak contibutions to the $b$ and $t$ quark masses and to the $\tau$ lepton mass in SUGRA models. The effects of CP phases on the supersymmetric contributions are found to be significanlty large for the b quark mass as they can change both its sign and its magnitude. Thus with the inclusion of CP phases the supersymmetric correction to the b quark mass can be as much as fifty percent or more of the total b quark mass. Read More

The branching ratio of the lightest Higgs decay into $b\bar b$, $\tau\bar\tau$ and $c\bar c$ is sensitive to supersymmetric effects. We include in this work the effects of CP phases on the Higgs decays. Specifically we compute the deviation of the CP phase dependent branching ratio from the standard model result. Read More

We compute supersymmetric QCD and supersymmetric electroweak corrections to the b and t quark masses and to the $\tau$ lepton mass in the presence of CP phases valid for all $\tan\beta$. The analysis includes one loop diagrams arising from the exchange of gluinos, charginos and neutralinos. We find that the CP effects can change both the magnitude as well as the sign of the supersymmetric loop correction. Read More

We discuss CP violation in supersymmetric theories and show that CP phenomena can act as a probe of their origins, i.e., compactification and spontaneous supersymmetry breaking. Read More

An analytic analysis of the CP violating effects arising from the soft SUSY breaking parameters on the decays $B^0_{s,d}\to \it l^+\it l^-$ at large $\tan\beta$ is given. It is found that the phases have a strong effect on the branching ratio and in some regions of the parameter space they can lead to a variation of the branching ratio by as much as 1-2 orders of magnitude. These results have important implications for the discovery of the $B^0_{s}\to \mu^+\mu^-$ signal in RUNII of the Tevatron and further on how the parameter space of SUSY models will be limited once the signal is found. Read More

A review is given of CP violation in a broad class of models based on supersymmetry, superstrings and brane models. Such models contain typically large CP violating phases which affect a variety of supersymmetric phenomenon at low energies and affect search for supersymmetry at colliders and in dark matter experiments. We focus here on few such phenomena, specifically the mixing of the CP even and the CP odd Higgs bosons which can be induced by loop corrections and on CP violation in the muon sector. Read More

A calculus for the derivatives of the eigen values of the neutralino mass matrix with respect to the CP violating background fields is developed and used to compute the mixings among the CP even and the CP odd Higgs sectors arising from the inclusion of the neutralino sector consisting of the neutralino, the Z boson, and the neutral Higgs bosons ($\chi^0_i-Z-h^0-H^0$) exchange in the loop contribution to the effective potential including the effects of large CP violating phases. Along with the stop, sbottom, stau and chargino-W-charged Higgs ($\chi^+-W-H^+$) contributions computed previously the present analysis completes the one loop corrections to the Higgs boson mass matrix in the presence of large phases. CP violation in the neutral Higgs sector is discussed in the above framework with specific focus on the mixings of the CP even and the CP odd sectors arising from the neutralino sector. Read More

A brief overview is given of recent developments in the analyses of large phases and CP violation in supersymmetric unified models. The problem of experimental electric dipole moment constraints and large phases is discussed. Implications of large phases on supersymmetric phenomena are reviewed. Read More

We analyze the electric dipole moment of the electron ($d_e$), of the neutron ($d_n$) and of the muon ($d_{\mu}$) using the cancellation mechanism in the presence of nonuniversalities of the soft breaking parameters. It is shown that the nonuniversalities in the slepton sector produce a strong violation of the scaling relation $d_{\mu}/d_e\simeq m_{\mu}/m_e$ in the cancellation region. An analysis of $d_e, d_n$ and $d_{\mu}$ under the constraints of the current experimental limits on $d_e$ and $d_n$ and under the constraints of the recent Brookhaven result on $g_{\mu}-2$ shows that in the non-scaling region $d_{\mu}$ can be as large as ($10^{-24}-10^{-23}$)ecm and thus within reach of the recently proposed Brookhaven experiment for a sensitive search for $d_{\mu}$ at the level of $10^{-24}$ ecm. Read More

We use the recently derived CP phase dependent analytic results for the supersymmetric electro-weak correction to $g_{\mu}-2$ to constrain the explicit CP phases in softly broken supersymmetry using the new physics effect seen in the g-2 Brookhaven measurement. It is shown that the BNL data strongly constrains the CP violating phase $\theta_{\mu}$ (the phase of the Higgs mixing parameter $\mu$) and $\xi_2$ (the phase of the SU(2) gaugino mass $\tilde m_2$) and as much as 60-90% of the region in the $\xi_2-\theta_{\mu}$ plane is eliminated over a significant region of the MSSM parameter space by the BNL constraint. The region of CP phases not excluded by the BNL experiment allows for large phases and for a satisfaction of the EDM constraints via the cancellation mechanism. Read More

The mixing among the CP even and the CP odd neutral Higgs bosons of MSSM by one loop induced effects in the presence of CP phases is investigated using three different mechanisms to satisfy the EDM constraints, i.e., a fine tuning of phases, a heavy sparticle spectrum, and the cancellation mechanism. Read More

We estimate the electron and neutron electric dipole moments in the focus point scenario of the minimal SUGRA model corresponding to large sfermion masses and moderate to large $\tan\beta$. There is a viable region of moderate fine-tuning in the parameter space, around $\tan\beta \simeq 5$, where the experimental limits on these electric dipole moments can be satisfied without assuming unnaturally small phase angles. But the fine-tuning constraints become more severe for $\tan\beta > 10$. Read More

One loop contributions to the Higgs boson masses and mixings from the chargino sector consisting of the chargino, the W, and the charged Higgs boson ($\chi^+-W-H^+$) exchanges and including the effects of large CP violating phases are computed. It is found that the chargino sector makes a large contribution to the mixings of the CP even and the CP odd Higgs sectors through the induced one loop effects and may even dominate the mixing generated by the stop and the sbottom sectors. Effects of the chargino sector contribution to the Higgs boson masses are also computed. Read More

A brief review is given of the effects of CP violation on the direct detection of neutralinos in dark matter detectors. We first summarize the current developments using the cancellation mechanism which allows for the existence of large CP violating phases consistent with experimental limits on the electron and on the neutron electric dipole moments in a broad class of SUSY, string and D brane models. We then discuss their effects on the scattering of neutralinos from quarks and on the event rates. Read More

The effects of large CP violating phases arising from the soft SUSY breaking parameters on the proton lifetime are investigated in supersymmetric grand unified models. It is found that the CP violating phases can reduce as well as enhance the proton lifetime depending on the part of the parameter space one is in. Modifications of the proton lifetime by as much as a factor of 2 due to the effects of the CP violating phases are seen. Read More

We show that EDMs obey a simple approximate scaling under the transformation $m_0\to \lambda m_0,m_{{1/2}}\to \lambda m_{{1/2}}$ in the large $\mu$ region when $\mu$ itself obeys the same scaling, ie., $\mu \to \lambda \mu$. In the scaling region the knowledge of a single point in the MSSM parameter space where the cancellation in the EDMs occur allows one to generate a trajectory in the $m_0-m_{{1/2}}$ plane where the cancellation mechanism holds and the EDMs are small. Read More

Effects of CP violation on the supersymmetric electro-weak correction to the anomalous magnetic moment of the muon are investigated with the most general allowed set of CP violating phases in MSSM. The analysis includes contributions from the chargino and the neutralino exchanges to the muon anomaly. The supersymmetric contributions depend only on specific combinations of CP phases. Read More

The one loop supersymmetric electro-weak correction to the anomalous magnetic moment of the muon is derived in the minimal N=1 supergravity unification with two CP violating phases. A numerical analysis of the CP violating effects on $g_{\mu}-2$ is carried out with the cancellation mechanism to guarantee the satisfaction of the experimental limits on the electric dipole moments of the electron and on the neutron. It is found that the effects of the CP phases can significantly affect the supersymmetric electro-weak correction to $g_{\mu}-2$, and that the numerical size of such a correction can be as large or larger than the Standard Model electro-weak correction to $g_{\mu}-2$. Read More