We discuss rare meson decays K + → π − ℓ + ℓ ′+ and D + → K − ℓ + ℓ ′+ (ℓ, ℓ ′ = e, µ) in a super... more We discuss rare meson decays K + → π − ℓ + ℓ ′+ and D + → K − ℓ + ℓ ′+ (ℓ, ℓ ′ = e, µ) in a supersymmetric extension of the standard model with explicit breaking of R-parity by bilinear Yukawa couplings in the superpotential. Estimates of the branching ratios for these decays are given. We also compare our numerical results with analogous ones previously obtained for two other mechanisms of lepton number violation: exchange by massive Majorana neutrinos and trilinear R-parity violation.
We compute the decay rates for the exclusive decays B ± → (η ′ , η)(K ± , K * ± ) and B 0 → (η ′ ... more We compute the decay rates for the exclusive decays B ± → (η ′ , η)(K ± , K * ± ) and B 0 → (η ′ , η)(K 0 , K * 0 ) in a QCD-improved factorization framework by including the contribution from the process b → sgg → s(η ′ , η) through the QCD anomaly. This method provides an alternative estimate of the contribution b → scc → s(η, η ′ ) to these decays as compared to the one using the intrinsic charm content of the η ′ and η mesons determined through the decays J/ψ → (η, η ′ , η c )γ. The advantage of computing the relevant matrix elements via the QCD anomaly governing the transition gg → (η ′ , η) is that there is no sign ambiguity in these contributions relative to the matrix elements from the rest of the operators in the weak effective Hamiltonian. Numerically, the QCD anomaly method and the one using the radiative decays J/ψ → (η, η ′ , η c )γ give similar branching ratios for the decays of interest here. The resulting branching ratios are compared with the CLEO data on B ± → η ′ K ± and B 0 → η ′ K 0 and predictions are made for the rest.
A brief account of the study of rare B decay $B \to K^\ast \ell^+ \ell^-$ using soft-collinear ef... more A brief account of the study of rare B decay $B \to K^\ast \ell^+ \ell^-$ using soft-collinear effective theory (SCET) is presented. Theoretical underpinning of this work is a factorization formula, derived to leading power in $1/m_b$ and valid to all orders in $\alpha_s$. Partially integrated branching ratio in the dilepton squared mass range $1 {GeV}^2 \le q^2 \le 7 {GeV}^2$ and the forward-backward (FB) asymmetry of the leptons are calculated. For the zero-point of the FB asymmetry, we get $q_0^2=(4.07^{+0.16}_{-0.13}) {GeV}^2$. The scale-related uncertainty of $q_0^2$ is improved compared to the earlier estimate of the same. Comment: 5 pages, 1 figure, requires style file ws-proc10x7-mod.cls; Presented at the XXXIII International Conference on High Energy Physics, Moscow, Russian Federation, 26th July - 2nd August 2006
We review and update the branching ratios for the $B \to (\rho,\omega) \gamma$ decays, calculated... more We review and update the branching ratios for the $B \to (\rho,\omega) \gamma$ decays, calculated in the QCD factorization approach in the next-to-leading order (NLO) in the strong coupling $\alpha_s$ and to leading power in $\Lambda_{\rm QCD}/m_b$. The corrections take into account the vertex, hard-spectator and annihilation contributions and are found to be large. Theoretical expectations for the branching ratios, CP-asymmetry, isospin- and $SU (3)_{\rm F}$-violating ratios in the $B \to \rho\gamma$ and $B \to \omega\gamma$ decays are presented and compared with the available data.
We review the salient features of $B$-meson physics, with particular emphasis on the measurements... more We review the salient features of $B$-meson physics, with particular emphasis on the measurements carried out at the $B$-factories and Tevatron, theoretical progress in understanding these measurements in the context of the standard model, and anticipation at the LHC. Topics discussed specifically are the current status of the Cabibbo-Kobayashi-Maskawa matrix, the CP-violating phases, rare radiative and semileptonic decays, and some selected non-leptonic two-body decays of the $B$ mesons.
... and single-charged prong energy distributions from subsequent τ + decays Ahmed Ali1,a, Eduard... more ... and single-charged prong energy distributions from subsequent τ + decays Ahmed Ali1,a, Eduard A. Kuraev2,b, Yury M. Bystritskiy2,c 1Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany 2JINR-BLTP, 141980 Dubna, Moscow region, Russian Federation ...
The angular distribution of the final electrons in the so-called long range mechanism of the neut... more The angular distribution of the final electrons in the so-called long range mechanism of the neutrinoless double beta decay ($0\nu2\beta$) is derived for the general Lorentz invariant effective Lagrangian. Possible theories beyond the SM are classified from their effects on the angular distribution, which could be used to discriminate among various particle physics models inducing $0\nu2\beta$ decays. However, additional input on the effective couplings will be required to single out the light Majorana-neutrino mechanism. Alternatively, measurements of the effective neutrino mass and angular distribution in $0\nu2\beta$ decays can be used to test the correlations among the parameters of the underlying physics models. This is illustrated for the left-right symmetric model, taking into account current phenomenological bounds.
We discuss the prospects of detecting the processes $e^+p\to\bar\nu_e\ell^+\ell'^+X$ and $\nu... more We discuss the prospects of detecting the processes $e^+p\to\bar\nu_e\ell^+\ell'^+X$ and $\nu_ep\to e\ell^+\ell'^+X$ ($\ell,\ell'=e,\mu,\tau$) under the conditions of the present $ep$ collider HERA and of future colliders. These high-energy processes are assumed to be mediated by the exchange of heavy Majorana neutrinos (HMN). We consider two simple scenarios for the HMN mass spectrum: the effective singlet ($m_1\ll m_2<m_3...$) and the effective doublet ($m_1<m_2\ll m_3...$). For the latter case, the cross section includes information about CP-violating phases.
We discuss rare meson decays $K^ + \to \pi ^ - \ell ^ + \ell '^ + $ and $D^ + \to K^ - \ell ^... more We discuss rare meson decays $K^ + \to \pi ^ - \ell ^ + \ell '^ + $ and $D^ + \to K^ - \ell ^ + \ell '^ +$ ($\ell, \ell'=e, \mu$) in a supersymmetric extension of the Standard Model with R-parity violation. Estimates of the branching ratios for these decays are presented.
A theoretical overview of the exotic spectroscopy in the charm and beauty quark sector is present... more A theoretical overview of the exotic spectroscopy in the charm and beauty quark sector is presented. These states are unexpected harvest from the $e^+e^-$ and hadron colliders and a permanent abode for the majority of them has yet to be found. We argue that some of these states, in particular the $Y_b(10890)$ and the recently discovered states $Z_b(10610)$ and $Z_b(10650)$, discovered by the Belle collaboration are excellent candidates for tetraquark states $[bq][\bar{b}\bar{q}]$, with $q=u,d$ light quarks. Theoretical analyes of the Belle data carried out in the tetraquark context is reviewed.
The neutrinoless double beta decay is analyzed using a general Lorentz invariant effective Lagran... more The neutrinoless double beta decay is analyzed using a general Lorentz invariant effective Lagrangian for various decaying nuclei of current experimental interest: $^{76}$Ge, $^{82}$Se, $^{100}$Mo, $^{130}$Te, and $^{136}$Xe. We work out the half-lives and angular correlation coefficients of the outgoing electrons in several scenarios for new physics: the left-right symmetric models, the R-parity-violating SUSY and models with leptoquarks. The theoretical uncertainty in the nuclear matrix elements is discussed.
We reexamine the branching ratios, CP -asymmetries, and other observables in a large number of B ... more We reexamine the branching ratios, CP -asymmetries, and other observables in a large number of B q → V V (q = u, d, s) decays in the perturbative QCD (PQCD) approach, where V denotes a light vector meson (ρ, K * , ω, φ). The essential difference between this work and the earlier similar works is of parametric origin and in the estimates of the power corrections related to the ratio
We discuss rare meson decays K + → π − ℓ + ℓ ′+ and D + → K − ℓ + ℓ ′+ (ℓ, ℓ ′ = e, µ) in a super... more We discuss rare meson decays K + → π − ℓ + ℓ ′+ and D + → K − ℓ + ℓ ′+ (ℓ, ℓ ′ = e, µ) in a supersymmetric extension of the standard model with explicit breaking of R-parity by bilinear Yukawa couplings in the superpotential. Estimates of the branching ratios for these decays are given. We also compare our numerical results with analogous ones previously obtained for two other mechanisms of lepton number violation: exchange by massive Majorana neutrinos and trilinear R-parity violation.
We compute the decay rates for the exclusive decays B ± → (η ′ , η)(K ± , K * ± ) and B 0 → (η ′ ... more We compute the decay rates for the exclusive decays B ± → (η ′ , η)(K ± , K * ± ) and B 0 → (η ′ , η)(K 0 , K * 0 ) in a QCD-improved factorization framework by including the contribution from the process b → sgg → s(η ′ , η) through the QCD anomaly. This method provides an alternative estimate of the contribution b → scc → s(η, η ′ ) to these decays as compared to the one using the intrinsic charm content of the η ′ and η mesons determined through the decays J/ψ → (η, η ′ , η c )γ. The advantage of computing the relevant matrix elements via the QCD anomaly governing the transition gg → (η ′ , η) is that there is no sign ambiguity in these contributions relative to the matrix elements from the rest of the operators in the weak effective Hamiltonian. Numerically, the QCD anomaly method and the one using the radiative decays J/ψ → (η, η ′ , η c )γ give similar branching ratios for the decays of interest here. The resulting branching ratios are compared with the CLEO data on B ± → η ′ K ± and B 0 → η ′ K 0 and predictions are made for the rest.
A brief account of the study of rare B decay $B \to K^\ast \ell^+ \ell^-$ using soft-collinear ef... more A brief account of the study of rare B decay $B \to K^\ast \ell^+ \ell^-$ using soft-collinear effective theory (SCET) is presented. Theoretical underpinning of this work is a factorization formula, derived to leading power in $1/m_b$ and valid to all orders in $\alpha_s$. Partially integrated branching ratio in the dilepton squared mass range $1 {GeV}^2 \le q^2 \le 7 {GeV}^2$ and the forward-backward (FB) asymmetry of the leptons are calculated. For the zero-point of the FB asymmetry, we get $q_0^2=(4.07^{+0.16}_{-0.13}) {GeV}^2$. The scale-related uncertainty of $q_0^2$ is improved compared to the earlier estimate of the same. Comment: 5 pages, 1 figure, requires style file ws-proc10x7-mod.cls; Presented at the XXXIII International Conference on High Energy Physics, Moscow, Russian Federation, 26th July - 2nd August 2006
We review and update the branching ratios for the $B \to (\rho,\omega) \gamma$ decays, calculated... more We review and update the branching ratios for the $B \to (\rho,\omega) \gamma$ decays, calculated in the QCD factorization approach in the next-to-leading order (NLO) in the strong coupling $\alpha_s$ and to leading power in $\Lambda_{\rm QCD}/m_b$. The corrections take into account the vertex, hard-spectator and annihilation contributions and are found to be large. Theoretical expectations for the branching ratios, CP-asymmetry, isospin- and $SU (3)_{\rm F}$-violating ratios in the $B \to \rho\gamma$ and $B \to \omega\gamma$ decays are presented and compared with the available data.
We review the salient features of $B$-meson physics, with particular emphasis on the measurements... more We review the salient features of $B$-meson physics, with particular emphasis on the measurements carried out at the $B$-factories and Tevatron, theoretical progress in understanding these measurements in the context of the standard model, and anticipation at the LHC. Topics discussed specifically are the current status of the Cabibbo-Kobayashi-Maskawa matrix, the CP-violating phases, rare radiative and semileptonic decays, and some selected non-leptonic two-body decays of the $B$ mesons.
... and single-charged prong energy distributions from subsequent τ + decays Ahmed Ali1,a, Eduard... more ... and single-charged prong energy distributions from subsequent τ + decays Ahmed Ali1,a, Eduard A. Kuraev2,b, Yury M. Bystritskiy2,c 1Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany 2JINR-BLTP, 141980 Dubna, Moscow region, Russian Federation ...
The angular distribution of the final electrons in the so-called long range mechanism of the neut... more The angular distribution of the final electrons in the so-called long range mechanism of the neutrinoless double beta decay ($0\nu2\beta$) is derived for the general Lorentz invariant effective Lagrangian. Possible theories beyond the SM are classified from their effects on the angular distribution, which could be used to discriminate among various particle physics models inducing $0\nu2\beta$ decays. However, additional input on the effective couplings will be required to single out the light Majorana-neutrino mechanism. Alternatively, measurements of the effective neutrino mass and angular distribution in $0\nu2\beta$ decays can be used to test the correlations among the parameters of the underlying physics models. This is illustrated for the left-right symmetric model, taking into account current phenomenological bounds.
We discuss the prospects of detecting the processes $e^+p\to\bar\nu_e\ell^+\ell'^+X$ and $\nu... more We discuss the prospects of detecting the processes $e^+p\to\bar\nu_e\ell^+\ell'^+X$ and $\nu_ep\to e\ell^+\ell'^+X$ ($\ell,\ell'=e,\mu,\tau$) under the conditions of the present $ep$ collider HERA and of future colliders. These high-energy processes are assumed to be mediated by the exchange of heavy Majorana neutrinos (HMN). We consider two simple scenarios for the HMN mass spectrum: the effective singlet ($m_1\ll m_2<m_3...$) and the effective doublet ($m_1<m_2\ll m_3...$). For the latter case, the cross section includes information about CP-violating phases.
We discuss rare meson decays $K^ + \to \pi ^ - \ell ^ + \ell '^ + $ and $D^ + \to K^ - \ell ^... more We discuss rare meson decays $K^ + \to \pi ^ - \ell ^ + \ell '^ + $ and $D^ + \to K^ - \ell ^ + \ell '^ +$ ($\ell, \ell'=e, \mu$) in a supersymmetric extension of the Standard Model with R-parity violation. Estimates of the branching ratios for these decays are presented.
A theoretical overview of the exotic spectroscopy in the charm and beauty quark sector is present... more A theoretical overview of the exotic spectroscopy in the charm and beauty quark sector is presented. These states are unexpected harvest from the $e^+e^-$ and hadron colliders and a permanent abode for the majority of them has yet to be found. We argue that some of these states, in particular the $Y_b(10890)$ and the recently discovered states $Z_b(10610)$ and $Z_b(10650)$, discovered by the Belle collaboration are excellent candidates for tetraquark states $[bq][\bar{b}\bar{q}]$, with $q=u,d$ light quarks. Theoretical analyes of the Belle data carried out in the tetraquark context is reviewed.
The neutrinoless double beta decay is analyzed using a general Lorentz invariant effective Lagran... more The neutrinoless double beta decay is analyzed using a general Lorentz invariant effective Lagrangian for various decaying nuclei of current experimental interest: $^{76}$Ge, $^{82}$Se, $^{100}$Mo, $^{130}$Te, and $^{136}$Xe. We work out the half-lives and angular correlation coefficients of the outgoing electrons in several scenarios for new physics: the left-right symmetric models, the R-parity-violating SUSY and models with leptoquarks. The theoretical uncertainty in the nuclear matrix elements is discussed.
We reexamine the branching ratios, CP -asymmetries, and other observables in a large number of B ... more We reexamine the branching ratios, CP -asymmetries, and other observables in a large number of B q → V V (q = u, d, s) decays in the perturbative QCD (PQCD) approach, where V denotes a light vector meson (ρ, K * , ω, φ). The essential difference between this work and the earlier similar works is of parametric origin and in the estimates of the power corrections related to the ratio
Spatial problems and a variety of abstract problems can be solved by humans with more ease if the... more Spatial problems and a variety of abstract problems can be solved by humans with more ease if the problem can be visualized and/or manipulated. Elaborating on the differences and interplay between representing spatial problems and solving them, this paper focuses on exploring the qualities of a strings and pins problem solving domain. This domain is compared to the straightedge and compass domain of Euclidean geometry. The strings and pins domain is described and two case studies are analyzed: (i) a strings and pins solution of the shortest path problem and (ii) a strings and pins solution to the Voronoi diagram problem; both approaches are compared to a formal solution. Differences and similarities between the straightedge and compass domain and the strings and pins domain are analyzed, and features and limitations of constructive and depictive geometry are discussed. Different problem solving phases are distinguished. Furthermore, cognitive aspects of different problem solving approaches are discussed.
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Papers by Ahmed Loai Ali