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Measurement of lepton momentum moments in the decay B ¯ → X l ν ¯ </mml:…

2003; American Physical Society; Volume: 67; Issue: 7 Linguagem: Inglês

10.1103/physrevd.67.072001

1538-4500

A. H. Mahmood, S. E. Csorna, I. Dankó, G. Bonvicini, D. Cinabro, M. Dubrovin, S. McGee, A. Bornheim, E. Lipeles, S. P. Pappas, A. Shapiro, W. Sun, A. J. Weinstein, R. A. Briere, G. P. Chen, T. Ferguson, G. Tatishvili, H. Vogel, N. E. Adam, J. Alexander, K. Berkelman, V. Boisvert, D. G. Cassel, P. S. Drell, J. E. Duboscq, K. M. Ecklund, R. Ehrlich, R. S. Galik, L. Gibbons, B. Gittelman, S. W. Gray, D. L. Hartill, B. K. Heltsley, L. Hsu, C. D. Jones, J. Kandaswamy, D. L. Kreinick, A. Magerkurth, H. Mahlke-Krüger, T. O. Meyer, N. B. Mistry, J. R. Patterson, D. Peterson, J. Pivarski, S. J. Richichi, D. Riley, A. J. Sadoff, H. Schwarthoff, M. R. Shepherd, J. G. Thayer, D. Urner, T. Wilksen, A. Warburton, M. Weinberger, S. B. Athar, P. Avery, L. Breva-Newell, V. Potlia, H. Stoeck, J. Yelton, K. Benslama, B. I. Eisenstein, G. D. Gollin, I. Karliner, N. Lowrey, C. Plager, C. Sedlack, M. Selen, J. J. Thaler, J. S. Williams, K. W. Edwards, R. Ammar, D. Besson, X. Zhao, S. Anderson, V. Frolov, D. T. Gong, Y. Kubota, S. Z. Li, R. Poling, A. Smith, C. J. Stepaniak, J. Urheim, Z. Metreveli, K. K. Seth, A. Tomaradze, P. Zweber, S. Ahmed, M. S. Alam, J. Ernst, L. Jian, M. Saleem, F. Wappler, K. Arms, E. Eckhart, K. K. Gan, C. Gwon, K. Honscheid, D. Hufnagel, H. Kagan, R. Kass, T. K. Pedlar, E. von Toerne, M. M. Zoeller, H. Severini, P. Skubic, S. A. Dytman, J. Mueller, S. Nam, V. Savinov, S. Chen, J. W. Hinson, J. Lee, D. H. Miller, V. Pavlunin, E. I. Shibata, I. P. J. Shipsey, D. Cronin-Hennessy, A. L. Lyon, C. S. Park, W. Park, J. B. Thayer, E. H. Thorndike, T. E. Coan, Y. S. Gao, F. Liu, Y. Maravin, R. Stroynowski, M. Artuso, C. Boulahouache, S. Blusk, K. Bukin, E. Dambasuren, R. Mountain, H. Muramatsu, R. Nandakumar, T. Skwarnicki, S. Stone, J. C. Wang,

High-Energy Particle Collisions Research

We measure the primary lepton momentum spectrum in $\overline{B}\ensuremath{\rightarrow}X\mathcal{l}\overline{\ensuremath{\nu}}$ decays, for ${p}_{\mathcal{l}}>~1.5\mathrm{GeV}/c$ in the B rest frame. From this, we calculate various moments of the spectrum. In particular, we find ${R}_{0}\ensuremath{\equiv}{\ensuremath{\int}}_{1.7\mathrm{GeV}}(d\ensuremath{\Gamma}{/dE}_{\mathrm{sl}}{)dE}_{\mathcal{l}}/{\ensuremath{\int}}_{1.5\mathrm{GeV}}(d\ensuremath{\Gamma}{/dE}_{\mathrm{sl}}{)dE}_{\mathcal{l}}=0.6187\ifmmode\pm\else\textpm\fi{}{0.0014}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.0016}_{\mathrm{sys}}$ and ${R}_{1}\ensuremath{\equiv}{\ensuremath{\int}}_{1.5\mathrm{GeV}}{E}_{\mathcal{l}}(d\ensuremath{\Gamma}{/dE}_{\mathrm{sl}}{)dE}_{\mathcal{l}}/{\ensuremath{\int}}_{1.5\mathrm{GeV}}(d\ensuremath{\Gamma}{/dE}_{\mathrm{sl}}{)dE}_{\mathcal{l}}=(1.7810\ifmmode\pm\else\textpm\fi{}{0.0007}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.0009}_{\mathrm{sys}})\mathrm{GeV}.$ We use these moments to determine non-perturbative parameters governing the semileptonic width. In particular, we extract the heavy quark expansion parameters $\overline{\ensuremath{\Lambda}}=(0.39\ifmmode\pm\else\textpm\fi{}{0.03}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.06}_{\mathrm{sys}}\ifmmode\pm\else\textpm\fi{}{0.12}_{\mathrm{th}})\mathrm{GeV}$ and ${\ensuremath{\lambda}}_{1}=(\ensuremath{-}0.25\ifmmode\pm\else\textpm\fi{}{0.02}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.05}_{\mathrm{sys}}\ifmmode\pm\else\textpm\fi{}{0.14}_{\mathrm{th}}){\mathrm{GeV}}^{2}.$ The theoretical constraints used are evaluated through order ${1/M}_{B}^{3}$ in the non-perturbative expansion and ${\ensuremath{\beta}}_{0}{\ensuremath{\alpha}}_{s}^{2}$ in the perturbative expansion. We use these parameters to extract $|{V}_{\mathrm{cb}}|$ from the world average of the semileptonic width and find $|{V}_{\mathrm{cb}}|=(40.8\ifmmode\pm\else\textpm\fi{}{0.5}_{{\ensuremath{\Gamma}}_{\mathrm{sl}}}\ifmmode\pm\else\textpm\fi{}{0.4}_{({\ensuremath{\lambda}}_{1},\overline{\ensuremath{\Lambda}}{)}_{\mathrm{exp}}}\ifmmode\pm\else\textpm\fi{}{0.9}_{\mathrm{th}})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}.$ In addition, we extract the short range b-quark mass ${m}_{b}^{1\mathrm{S}}=(4.82\ifmmode\pm\else\textpm\fi{}{0.07}_{\mathrm{exp}}\ifmmode\pm\else\textpm\fi{}{0.11}_{\mathrm{th}})\mathrm{GeV}{/c}^{2}.$ Finally, we discuss the implications of our measurements for the theoretical understanding of inclusive semileptonic processes.