Showing papers by "Ahmed Ali published in 2000"

A Comparative study of the decays $B \to$ ($K$, $K^{*)} \ell^+ \ell^-$ in standard model and supersymmetric theories

Abstract: Using improved theoretical calculations of the decay form factors in the Light Cone-QCD sum rule approach, we investigate the decay rates, dilepton invariant mass spectra and the forward-backward (FB) asymmetry in the decays B → (K, K ∗ )l + l − (l ± = e ± , µ ± , τ ± ) in the standard model (SM) and a number of popular variants of the supersymmetric (SUSY) models. Theoretical precision on the differential decay rates and FB-asymmetry is estimated in these theories taking into account various parametric uncertainties. We show that existing data on B → Xsγ and the experimental upper limit on the branching ratio B(B → K ∗ µ + µ − ) provide interesting bounds on the coefficients of the underlying effective theory. We argue that the FB-asymmetry in B → K ∗ l + l − constitutes a precision test of the SM and its measurement in forthcoming experiments may reveal new physics. In particular, the presently allowed largetan β solutions in SUGRA models, as well as more general flavor-violating SUSY models, yield FB-asymmetries which are characteristically different from the corresponding ones in the SM.

Supersymmetric effects on isospin symmetry breaking and direct CP violation in B-->ργ

Abstract: We argue that one can search for physics beyond the standard model through measurements of the isospin-violating quantity ${\ensuremath{\Delta}}^{\ensuremath{-}0}\ensuremath{\equiv}\ensuremath{\Gamma}{(B}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{\ensuremath{-}}\ensuremath{\gamma})/2\ensuremath{\Gamma}{(B}^{0}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{0}\ensuremath{\gamma})\ensuremath{-}1,$ its charge conjugate ${\ensuremath{\Delta}}^{+0},$ and direct $\mathrm{CP}$ violation in the partial decay rates of ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\gamma}.$ We illustrate this by working out theoretical profiles of both the charge-conjugate averaged ratio $\ensuremath{\Delta}\ensuremath{\equiv}\frac{1}{2}({\ensuremath{\Delta}}^{+0}+{\ensuremath{\Delta}}^{\ensuremath{-}0})$ and the $\mathrm{CP}$ asymmetry ${\mathcal{A}}_{\mathrm{CP}}{(B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\gamma})$ in the standard model and in some variants of the minimal supersymmetric standard model. We find that chargino contributions in the large $\mathrm{tan}\ensuremath{\beta}$ region may modify the magnitudes and flip the signs of $\ensuremath{\Delta}$ and ${\mathcal{A}}_{\mathrm{CP}}{(B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\gamma}),$ compared to their standard-model values, thereby providing an unmistakable signature of supersymmetry.

Chemical and biological studies of Sinapis arvensis growing in Egypt

Abstract: From the Et acetate fraction of the alc. ext. of the flowers of Sinapis arvensis L. a new compd. given the name: (2,​2'-​diacetyloxy-​3,​3'-​dihydroxy)​-​1,​1'-​dipropylether. In addn., three flavonoidal glycosides were also isolated and identified as: kaempferol-​3-​O-​β-​glucopyranoside, isorhamnetin-​3,​7-​O-​β-​diglucopyranoside and isorhamnetin-​3-​O-​β-​glucopyranoside-​7-​O-​α-​rhamnopyranoside. Meanwhile the chloroform fraction of the alc. ext. of the seeds afforded β-​amyrin, β-​sitosterol, β-​sitosterol-​3-​O-​β-​glucopyranoside and syringin. The GC​/MS anal. of the fixed oil of the seeds revealed the presence of 14 fatty acids including a high percent (11.56​%) of harmful erucic acid. The identification of the isolated compds. was based on different methods of phys., chem. and spectral anal. Moreover the biol. screening showed that the alc. ext. of the leaf, the flavonoids of the flower and to a lesser extent the oil of the seed possesses a significant antimicrobial activity, while the flavonoids of the flower showed a significant anti-​inflammatory activity. In addn., the oil of the seed showed insignificant diuretic activity.

b Quark Physics with 2 .10^9 Z Bosons

Abstract: It has been suggested to realize a factory for 10^9 Z^0 through a linear e^+e^- collider with polarized beams. Very likely the relevant CP studies for B mesons will already have been performed at the B factories by that time, hence GIGA-Z will be a third generation b physics experiment. Yet such a facility would provide us with unique opportunities in the domain of beauty physics that would be of essential significance even in 2010: (1) Production and decay of polarized beauty baryons; (2) searching for and probing transitions driven by b --> q u \bar{ u}; (3) detailed and comprehensive studies of inclusive semileptonic B_s decays.