R. Ayad

ORCID: 0000-0003-3466-9290
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About
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Research Areas
  • Particle physics theoretical and experimental studies
  • Quantum Chromodynamics and Particle Interactions
  • High-Energy Particle Collisions Research
  • Neutrino Physics Research
  • Particle Detector Development and Performance
  • Dark Matter and Cosmic Phenomena
  • Particle Accelerators and Free-Electron Lasers
  • Computational Physics and Python Applications
  • Medical Imaging Techniques and Applications
  • Black Holes and Theoretical Physics
  • Atomic and Subatomic Physics Research
  • Radiation Detection and Scintillator Technologies
  • Superconducting Materials and Applications
  • Nuclear physics research studies
  • Cosmology and Gravitation Theories
  • Particle accelerators and beam dynamics
  • Astrophysics and Cosmic Phenomena
  • Distributed and Parallel Computing Systems
  • Advanced Data Storage Technologies
  • Nuclear Physics and Applications
  • Radiation Effects in Electronics
  • Lanthanide and Transition Metal Complexes
  • Radiation Therapy and Dosimetry
  • Quantum chaos and dynamical systems
  • Advanced Radiotherapy Techniques

University of Tabuk
2015-2024

Deutsches Elektronen-Synchrotron DESY
2016-2024

University of the Basque Country
2015-2022

University of Bonn
2016-2022

Campbell Collaboration
2009-2022

Duke University
2019-2022

Chonnam National University
2018-2022

University of Cincinnati
2000-2020

University of Florida
2000-2020

Karlsruhe Institute of Technology
2019

Based on the full BABAR data sample, we report improved measurements of ratios R(D(*))=B(B[over ¯]→D(*)τ(-)ν[over ¯](τ))/B(B[over ¯]→D(*)ℓ(ℓ)(-)ν[over ¯](ℓ)), where ℓ is either e or μ. These are sensitive to new physics contributions in form a charged Higgs boson. We measure R(D)=0.440±0.058±0.042 and R(D(*))=0.332±0.024±0.018, which exceed standard model expectations by 2.0σ 2.7σ, respectively. Taken together, our results disagree with these at 3.4σ level. This excess cannot be explained...

10.1103/physrevlett.109.101802 article EN publisher-specific-oa Physical Review Letters 2012-09-06

Based on the full BaBar data sample, we report improved measurements of ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B l Nu), where is either e or mu. These are sensitive to new physics contributions in form a charged Higgs boson. We measure R(D) 0.440 +- 0.058 0.042 and R(D*) 0.332 0.024 0.018, which exceed Standard Model expectations by 2.0 sigma 2.7 sigma, respectively. Taken together, our results disagree with these at 3.4 level. This excess cannot be explained boson type II two-Higgs-doublet...

10.1103/physrevd.88.072012 article EN Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology 2013-10-31

We report a measurement of the branching fraction ratios R(D(*)) Bbar -> D(*) tau- nubar_tau relative to D()* l- nubar_l (where l = e or mu) using full Belle data sample 772 x 10^6 BBbar pairs collected at Y(4S) resonance with detector KEKB asymmetric-energy e+e- collider. The measured values are R(D)= 0.375 +- 0.064(stat.) 0.026(syst.) and R(D*) 0.293 0.038(stat.) 0.015(syst.). analysis uses hadronic reconstruction tag-side B meson purely leptonic tau decays. results consistent earlier...

10.1103/physrevd.92.072014 article EN publisher-specific-oa Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology 2015-10-26

We report the first measurement of $\ensuremath{\tau}$ lepton polarization ${P}_{\ensuremath{\tau}}({D}^{*})$ in decay $\overline{B}\ensuremath{\rightarrow}{D}^{*}{\ensuremath{\tau}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ as well a new ratio branching fractions...

10.1103/physrevlett.118.211801 article EN publisher-specific-oa Physical Review Letters 2017-05-26

Dark sectors charged under a new Abelian interaction have recently received much attention in the context of dark matter models. These models introduce light mediator, so-called photon (A′), connecting sector to standard model. We present search for reaction e+e−→γA′, A′→e+e−, μ+μ− using 514 fb−1 data collected with BABAR detector. observe no statistically significant deviations from model predictions, and we set 90% confidence level upper limits on mixing strength between at 10−4−10−3...

10.1103/physrevlett.113.201801 article EN publisher-specific-oa Physical Review Letters 2014-11-10

We report a measurement of the ratio ${\cal R}(D^*) = {\cal B}(\bar{B}^0 \rightarrow D^{*+} \tau^- \bar{\nu}_{\tau})/{\cal \ell^- \bar{\nu}_{\ell})$, where $\ell$ denotes an electron or muon. The results are based on data sample containing $772\times10^6$ $B\bar{B}$ pairs recorded at $\Upsilon(4S)$ resonance with Belle detector KEKB $e^+ e^-$ collider. select $B^0 \bar{B}^0$ by reconstructing both $B$ mesons in semileptonic decays to $D^{*\mp} \ell^{\pm}$. measure R}(D^*)= 0.302 \pm...

10.1103/physrevd.94.072007 article EN publisher-specific-oa Physical review. D/Physical review. D. 2016-10-27

We present a measurement of angular observables and test lepton flavor universality in the $B\ensuremath{\rightarrow}{K}^{*}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ decay, where $\ensuremath{\ell}$ is either $e$ or $\ensuremath{\mu}$. The analysis performed on data sample corresponding to an integrated luminosity $711\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ containing $772\ifmmode\times\else\texttimes\fi{}1{0}^{6}$ $B\overline{B}$ pairs, collected at...

10.1103/physrevlett.118.111801 article EN publisher-specific-oa Physical Review Letters 2017-03-13

With the full data sample of $772 \times 10^6$ $B{\bar B}$ pairs recorded by Belle detector at KEKB electron-positron collider, decay $\bar{B} \rightarrow D^* \tau^- \bar{\nu}_\tau$ is studied with hadronic $\tau$ decays $\tau^- \pi^- \nu_\tau$ and \rho^- \nu_\tau$. The polarization $P_\tau(D^*)$ in two-body measured, as well ratio branching fractions $R(D^{*}) = \mathcal{B}(\bar {B} \bar{\nu}_\tau) / \mathcal{B}(\bar{B} \ell^- \bar{\nu}_\ell)$, where $\ell^-$ denotes an electron or a muon....

10.1103/physrevd.97.012004 article EN cc-by Physical review. D/Physical review. D. 2018-01-10

We present a measurement of ${R}_{{K}^{*}}$, the branching fraction ratio $\mathcal{B}(B\ensuremath{\rightarrow}{K}^{*}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})/\mathcal{B}(B\ensuremath{\rightarrow}{K}^{*}{e}^{+}{e}^{\ensuremath{-}})$, for both charged and neutral $B$ mesons. The case ${R}_{{K}^{*+}}$ is first ever performed. In addition, we report absolute fractions individual modes in bins squared dilepton invariant mass ${q}^{2}$. analysis based on data sample $711\text{...

10.1103/physrevlett.126.161801 article EN cc-by Physical Review Letters 2021-04-22

We present measurements of the branching fractions for decays $B\to K \mu^{+}\mu^{-}$ and e^{+}e^{-}$, their ratio ($R_{K}$), using a data sample 711 $fb^{-1}$ that contains $772 \times 10^{6}$ $B\bar{B}$ events. The were collected at $\Upsilon(4S)$ resonance with Belle detector KEKB asymmetric-energy $e^{+}e^{-}$ collider. $R_{K}$ is measured in five bins dilepton invariant-mass-squared ($q^{2}$): $q^{2} \in (0.1, 4.0), (4.0, 8.12), (1.0, 6.0)$, $(10.2, 12.8)$ ($>14.18) GeV^{2}/c^{4}$,...

10.1007/jhep03(2021)105 article EN cc-by Journal of High Energy Physics 2021-03-01

A precise measurement of the cross section process $e^+e^-\toπ^+π^-(γ)$ from threshold to an energy 3GeV is obtained with initial-state radiation (ISR) method using 232fb$^{-1}$ data collected BaBar detector at $e^+e^-$ center-of-mass energies near 10.6GeV. The ISR luminosity determined a study leptonic $e^+e^-\toμ^+μ^-(γ)γ_{\rm ISR}$, which found agree next-to-leading-order QED prediction within 1.1%. for systematic uncertainty 0.5% in dominant $ρ$ resonance region. leading-order hadronic...

10.1103/physrevd.86.032013 article EN publisher-specific-oa Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology 2012-08-28

In a sample of $471\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ events collected with the BABAR detector at PEP-II ${e}^{+}{e}^{\ensuremath{-}}$ collider we study rare decays $B\ensuremath{\rightarrow}{K}^{(*)}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$, where ${\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ is either or ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$. We report results on partial branching fractions and isospin...

10.1103/physrevd.86.032012 article EN publisher-specific-oa Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology 2012-08-24

We search for the flavor-changing neutral-current decays $B\ensuremath{\rightarrow}{K}^{(*)}\ensuremath{\nu}\overline{\ensuremath{\nu}}$, and invisible $J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ $\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ via $B\ensuremath{\rightarrow}{K}^{(*)}J/\ensuremath{\psi}$ $B\ensuremath{\rightarrow}{K}^{(*)}\ensuremath{\psi}(2S)$, respectively, using a data sample of...

10.1103/physrevd.87.112005 article EN publisher-specific-oa Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology 2013-06-05

We present a study of the decays B^{0,+} --> J/psi pi^+ pi^- pi^0 K^{0,+}, using 467 10^6 BBbar pairs recorded with BABAR detector. evidence for decay mode X(3872) omega, product branching fractions B(B^+ X(3872)K^+) B(X(3872) omega) =[0.6\pm0.2\stat \pm 0.1\syst ] 10^{-5}, and B(B^0 X(3872)K^0) =[0.6\pm0.3\stat 10^{-5}. A detailed mass distribution from favors negative-parity assignment.

10.1103/physrevd.82.011101 article EN cc-by Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology 2010-07-09

We present the results of an amplitude analysis anti-B0 -> J/psi K- pi+ decays. A new charged charmoniumlike state Zc(4200)+ decaying to is observed with a significance 6.2 sigma. The mass and width are 4196 +31-29 +17-13 MeV/c^2 370 +70-70 +70-132 MeV, respectively; preferred assignment quantum numbers J^P = 1^+. In addition, we find evidence for Zc(4430)+ pi+. based on 711 fb^-1 data sample collected by Belle detector at asymmetric-energy e+ e- collider KEKB.

10.1103/physrevd.90.112009 article EN publisher-specific-oa Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology 2014-12-16

The process e+e- --> p anti-p gamma is studied using 469 fb-1 of integrated luminosity collected with the BABAR detector at PEP-II collider, an center-of-mass energy 10.6 GeV. From analysis invariant mass spectrum, dependence cross section for measured from threshold to 4.5 ratio electric and magnetic form factors, |G_E/G_M|, asymmetry in proton angular distribution are masses below 3 We also measure branching fractions decays J/psi psi(2S) anti p.

10.1103/physrevd.87.092005 article EN publisher-specific-oa Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology 2013-05-10

We present the results of a search for rare decays $B\to h\nu\overline{\nu}$, where $h$ stands $K^+,\:K^0_{\mathrm{S}},\:K^{\ast +},\:K^{\ast 0},\:\pi^+,\:\pi^0,\:\rho^+$ and $\rho^{0}$. The are obtained with $772\times10^{6}$ $B\overline{B}$ pairs collected Belle detector at KEKB $e^+ e^-$ collider. reconstruct one $B$ meson in semileptonic decay require single but nothing else on signal side. observe no significant set upper limits branching fractions. K^0_{\mathrm{S}}\nu\overline{\nu}$,...

10.1103/physrevd.96.091101 article EN publisher-specific-oa Physical review. D/Physical review. D. 2017-11-27

Although CP violation in the B meson system has been well established by factories, there no direct observation of time-reversal violation. The decays entangled neutral mesons into definite flavor states (B(0) or B(0)), and J/ψK(L)(0) ccK(S)(0) final (referred to as B(+) B(-)), allow comparisons between probabilities four pairs T-conjugated transitions, for example, B(0) → B(-) B(0), a function time difference two decays. Using 468 × 10(6) BB produced Υ(4S) collected BABAR detector at SLAC,...

10.1103/physrevlett.109.211801 article EN publisher-specific-oa Physical Review Letters 2012-11-19

We present an analysis of exclusive charmless semileptonic B-meson decays based on 377 million BBbar pairs recorded with the BABAR detector at Upsilon(4S) resonance. select four event samples corresponding to decay modes B0 --> pi- l+ nu, B+ pi0 rho- and -> rho0 find measured branching fractions be consistent isospin symmetry. Assuming symmetry, we combine two B pi l nu samples, similarly rho measure BF(B0 nu) = (1.41 +- 0.05 0.07) x 10^-4 (1.75 0.15 0.27) 10^-4, where errors are statistical...

10.1103/physrevd.83.032007 article EN publisher-specific-oa Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology 2011-02-07

We present a study of the ${D}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, ${D}^{0}{\ensuremath{\pi}}^{+}$, and ${D}^{*+}{\ensuremath{\pi}}^{\ensuremath{-}}$ systems in inclusive ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}c\overline{c}$ interactions search for new excited $D$ meson states. use data set, consisting $\ensuremath{\sim}454\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, collected at center-of-mass energies near 10.58 GeV by BABAR detector SLAC PEP-II asymmetric-energy...

10.1103/physrevd.82.111101 article EN Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology 2010-12-01

We present a determination of the magnitude Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ using decay $B\to D\ell\nu_\ell$ ($\ell=e,\mu$) based on 711 fb$^{-1}$ $e^+e^-\to \Upsilon(4S)$ data recorded by Belle detector and containing $772 \times 10^6$ $B\bar{B}$ pairs. One $B$ meson in event is fully reconstructed hadronic mode while other, signal side, partially from charged lepton either $D^+$ or $D^0$ total 23 modes. The isospin-averaged branching fraction found to be...

10.1103/physrevd.93.032006 article EN publisher-specific-oa Physical review. D/Physical review. D. 2016-02-25

We report measurement of the cross section $e^+e^-\to \pi^+\pi^-\psi(2S)$ between 4.0 and $5.5 {\rm GeV}$, based on an analysis initial state radiation events in a $980 \rm fb^{-1}$ data sample recorded with Belle detector. The properties $Y(4360)$ $Y(4660)$ states are determined. Fitting mass spectrum $\pi^+\pi^-\psi(2S)$ two coherent Breit-Wigner functions, we find solutions identical width but different couplings to electron-positron pairs: $M_{Y(4360)} = (4347\pm 6\pm 3) MeV}/c^2$,...

10.1103/physrevd.91.112007 article EN Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology 2015-06-12

We present a measurement of angular observables and test lepton flavor universality in the $B\to K^\ast \ell^+\ell^-$ decay, where $\ell$ is either $e$ or $μ$. The analysis performed on data sample corresponding to an integrated luminosity $711~\mathrm{fb}^{-1}$ containing $772\times 10^{6}$ $B\bar B$ pairs, collected at $Υ(4S)$ resonance with Belle detector asymmetric-energy $e^+e^-$ collider KEKB. result consistent Standard Model (SM) expectations, largest discrepancy from SM prediction...

10.48550/arxiv.1612.05014 preprint EN other-oa arXiv (Cornell University) 2016-01-01

We present a measurement of angular observables, $P_4'$, $P_5'$, $P_6'$, $P_8'$, in the decay $B^0 \to K^\ast(892)^0 \ell^+ \ell^-$, where $\ell^+\ell^-$ is either $e^+e^-$ or $\mu^+\mu^-$. The analysis performed on data sample corresponding to an integrated luminosity $711~\mathrm{fb}^{-1}$ containing $772\times 10^{6}$ $B\bar B$ pairs, collected at $\Upsilon(4S)$ resonance with Belle detector asymmetric-energy collider KEKB. Four $P_{4,5,6,8}'$ are extracted five bins invariant mass...

10.48550/arxiv.1604.04042 preprint EN other-oa arXiv (Cornell University) 2016-01-01
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