Advertisement

Measurement of |V cb | using the semileptonic decay \(\overline{\rm {B^{0}_{d}}} \rightarrow {\rm D}^* \ell^- \overline{\nu}_{\ell}\)

  • The DELPHI Collaboration
experimental physics

Abstract.

Data from Z decays in DELPHI have been searched for \(\overline{\rm B^0_d}\rightarrow {\rm D}^{* + } \ell^- \overline{\nu}_{\ell}\) with the \({\rm D}^{* + }\) decaying to \({\rm D}^0 \pi^ + \) and \({\rm D}^0 \rightarrow {\rm K}^- \pi^ + \), \({\rm K}^- \pi^ + \pi^ + \pi^-\) or \({\rm K}^- \pi^ + (\pi^0)\). These events are used to measure the CKM matrix element \(\left\vert{\rm V}_{cb} \right\vert\) and the form factor slope, \(\rho_{A_1}^2\): \({\cal F}_{D^*}(1) \left\vert{\rm V}_{cb} \right\vert = 0.0392 \pm 0.0018 \pm 0.0023; \rho_{A_1}^2 = 1.32 \pm 0.15 \pm 0.33 \) corresponding to a branching fraction: \({\rm BR}(\overline{\rm B^0_d}\rightarrow {\rm D}^{* + } \ell^- \overline{\nu}_{\ell}) = (5.90 \pm 0.22 \pm 0.50)\%. \) Combining these and previous DELPHI measurements gives: \( {\cal F}_{D^*}(1)\left|{\rm V}_{cb} \right|= 0.0377 \pm 0.0011 \pm 0.0019,\quad \rho_{A_1}^2 = 1.39 \pm 0.10 \pm 0.33\) and \({\rm BR}(\overline{\rm B^0_d}\rightarrow {\rm D}^{* + } \ell^- \overline{\nu}_{\ell}) = (5.39 \pm 0.11 \pm 0.34)\% \) Using \({\cal F}_{D^*}(1) = 0.91 \pm 0.04\), yields: \( \left|{\rm V}_{cb} \right|= 0.0414 \pm 0.0012\textrm{(stat.)} \pm 0.0021\textrm{(syst.)} \pm 0.0018\textrm{(theory)}. \) The b-quark semileptonic branching fraction into a \({\rm D}^{* + }\) emitted from higher mass charmed excited states has also been measured to be: \({\rm BR}(b \rightarrow {\rm D}^{* + } {\rm X} \ell^- \overline{\nu}_{\ell}) = (0.67\pm 0.08\pm0.10)\% \)

Keywords

Excited State Matrix Element Form Factor High Mass Factor Slope 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    A.F. Falk, M. Neubert, Phys. Rev. D 47, 2965 (1993) and 2982; T. Mannel, Phys. Rev. D 50, 428 (1994); M.A. Shifman, N.G. Uraltsev, A.I. Vainshtein, Phys. Rev. D 51, 2217 (1995), Erratum-ibid. D 52, 3149 (1995)CrossRefGoogle Scholar
  2. 2.
    P. Abreu et al., DELPHI Collaboration, Z. Phys. C 71, 539 (1996)CrossRefGoogle Scholar
  3. 3.
    M. Neubert, Phys. Rept. 245, 259-396 (1994)CrossRefGoogle Scholar
  4. 4.
    J.E. Dubosq et al., CLEO Collaboration, Phys. Rev. Lett. 76, 3898 (1996)CrossRefGoogle Scholar
  5. 5.
    I. Caprini, L. Lellouch, M. Neubert, Nucl. Phys. B 530, 153 (1998)CrossRefGoogle Scholar
  6. 6.
    C.G. Boyd, B. Grinstein, R.F. Lebed, Phys. Rev. D 56, 6895 (1997)CrossRefGoogle Scholar
  7. 7.
    N. Isgur, M. Wise, Phys. Lett. B 232, 113 (1989); Phys. Lett. B 237, 527 (1990)CrossRefGoogle Scholar
  8. 8.
    A. F. Falk, H. Georgi, B. Grinstein, M. B. Wise, Nucl. Phys. B 343, 1 (1990)CrossRefGoogle Scholar
  9. 9.
    Particle Data Group, K. Hagiwara et al., Phys. Rev. D 66, 010001 (2002)CrossRefGoogle Scholar
  10. 10.
    DELPHI Collaboration, P. Abreu et al., Nucl. Instr. Methods A 378, 57 (1996)Google Scholar
  11. 11.
    T. Sjöstrand, Comp. Phys. Comm. 82, 74 (1994)CrossRefGoogle Scholar
  12. 12.
    R. Barate et al., ALEPH Collaboration, Eur. Phys. J. C 4, 387 (1998)CrossRefGoogle Scholar
  13. 13.
    B. Aubert et al., BaBar Collaboration, SLAC-PUB-9736, hep-ex/0305003Google Scholar
  14. 14.
    Combined results on b-hadron production rates, lifetimes, oscillations and semileptonic decays (ALEPH, CDF, DELPHI, L3, OPAL, SLD), CERN-EP/2001-050, hep-ex/0112028Google Scholar
  15. 15.
    A.H. Hoang, Z. Ligeti, A.V. Manohar, Phys. Rev. D 59, 074017 (1999)CrossRefGoogle Scholar
  16. 16.
    ALEPH Collaboration, Phys. Lett. B 512, 30 (2001)CrossRefGoogle Scholar
  17. 17.
    P. Abreu et al., DELPHI Collaboration, Phys. Lett. B 425, 399 (1998)CrossRefGoogle Scholar
  18. 18.
    P. Abreu et al., DELPHI Collaboration. Eur. Phys. J. C 20, 455 (2001)Google Scholar
  19. 19.
    A.K. Leibovich, Z. Ligeti, I.W. Stewart, M.B. Wise, Phys. Rev. D 57, 308 (1998)Google Scholar
  20. 20.
    P. Abreu et al., DELPHI Collaboration, Phys. Lett. B 510, 55 (2001)CrossRefGoogle Scholar
  21. 21.
    D. Buskulic et al., ALEPH Collaboration, Phys. Lett. B 395, 373 (1997)CrossRefGoogle Scholar
  22. 22.
    G. Abbiendi et al., OPAL Collaboration, Phys. Lett. B 482, 15 (2000)CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin/Heidelberg 2004

Authors and Affiliations

  • The DELPHI Collaboration

There are no affiliations available

Personalised recommendations