arXiv subjects

A. H. Mahmood

Publications and source records attributed to A. H. Mahmood.

5 recordsLinked to original sources

arXiv2004

Measurement of the B-Meson Inclusive Semileptonic Branching Fraction and Electron-Energy Moments

We report a new measurement of the B-meson semileptonic decay momentum spectrum that has been made with a sample of 9.4/fb of electron-positron annihilation data collected with the CLEO II detector at the Y(4S) resonance. Electrons from primary semileptonic decays and secondary charm decays were separated by using charge and angular correlations in Y(4S) events with a high-momentum lepton and an additional electron. We determined the semileptonic branching fraction to be (10.91 +- 0.09 +- 0.24)% from the normalization of the electron-energy spectrum. We also measured the moments of the electron energy spectrum with minimum energies from 0.6 GeV to 1.5 GeV.

hep-ex↗

arXiv2002

Measurement of Lepton Momentum Moments in the Decay bar{B} \to X \ell \barν and Determination of Heavy Quark Expansion Parameters and |V_cb|

We measure the primary lepton momentum spectrum in B-bar to X l nu decays, for p_l > 1.5 GeV/c in the B rest frame. From this, we calculate various moments of the spectrum. In particular, we find R_0 = [int(E_l>1.7) (dGam/dE_sl)*dE_l] / [int(E_l>1.5) (dGam/dE_sl)*dE_l] = 0.6187 +/- 0.0014_stat +/- 0.0016_sys and R_1 = [int(E_l>1.5) E_l(dGam/dE_sl)*dE_l] / [int(E_l>1.5) (dGam/dE_sl)*dE_l] = (1.7810 +/- 0.0007_stat +/- 0.0009_sys) GeV. We use these moments to determine non-perturbative parameters governing the semileptonic width. In particular, we extract the Heavy Quark Expansion parameters Lambda-bar = (0.39 +/- 0.03_stat +/- 0.06_sys +/- 0.12_th) GeV and lambda_1 = (-0.25 +/- 0.02_stat +/- 0.05_sys +/- 0.14_th) GeV^2. The theoretical constraints used are evaluated through order 1/M_B^3 in the non-perturbative expansion and beta_0*alpha__s^2 in the perturbative expansion. We use these parameters to extract |V_cb| from the world average of the semileptonic width and find |V_cb| = (40.8 +/- 0.5_Gam-sl +/- 0.4_(lambda_1,Lambda-bar)-exp +/- 0.9_th) x 10^-3. In addition, we extract the short range b-quark mass m_b^1S = (4.82 +/- 0.07_exp +/- 0.11_th) GeV/c^2. Finally, we discuss the implications of our measurements for the theoretical understanding of inclusive semileptonic processes.

hep-ex↗

arXiv2002

Search for eta_b(1S) in Inclusive Radiative Decays of the Upsilon(3S)

We have searched for the bottomonium eta_b(1S) via the hindered magnetic dipole (M1) photon transition Upsilon(3S) -> gamma eta_b(1S). No evidence for such a transition is found in the data sample of 4.7 x 10^6 Upsilon(3S)'s collected with the CLEO-III detector. We set upper limits on the branching ratio from 9.30 to 9.43 GeV/c^2 of eta_b(1S) masses. These upper limits rule out many previously published phenomenological estimates of the rate for this transition.

hep-ex↗

arXiv2001

Measurement of the Xi^+_c Lifetime

The Xi^+_c lifetime is measured using 9.0 fb^-1 of e+e- annihilation data collected on and just below the Upsilon(4S) resonance with the CLEO II.V detector at CESR. This is the first measurement of the Xi^+_c lifetime from a collider experiment. Using an unbinned maximum likelihood fit, the Xi^+_c lifetime is measured to be 503 +/- 47 (stat.) +/- 18 (syst.) fs. The precision of this measurement is comparable to previous measurements carried out by fixed target experiments with different sources of systematic uncertainties.

hep-ex↗

arXiv2000

Measurement of the $Λ_{c}^{+}$ Lifetime

The $Λ_{c}^{+}$ lifetime is measured using 9.0 fb$^{-1}$ of $e^+e^-$ annihilation data collected on or just below the $Υ(4S)$ resonance with the CLEO II.V detector at CESR. Using an unbinned maximum likelihood fit, the $Λ_{c}^{+}$ lifetime is measured to be $(179.6 \pm 6.9(stat.) \pm 4.4(syst.))$ fs. The precision of this colliding beam measurement is comparable to other measurements, which are based on fixed target experiments with different systematic errors.

hep-ex↗