Differential branching fraction and angular analysis of the decay B 0K ∗0 μ + μ


The angular distribution and differential branching fraction of the decay B 0K ∗0 μ + μ are studied using a data sample, collected by the LHCb experiment in pp collisions at \( \sqrt{s}=7 \) TeV, corresponding to an integrated luminosity of 1.0 fb−1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be \( q_0^2={{{4.9\pm 0.9\;\mathrm{Ge}{{\mathrm{V}}^2}}} \left/ {{{c^4}}} \right.} \), where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions.


  1. [1]

    W. Altmannshofer et al., Symmetries and asymmetries of BK μ + μ decays in the standard model and beyond, JHEP 01 (2009) 019 [arXiv:0811.1214] [INSPIRE].

    ADS  Article  Google Scholar 

  2. [2]

    C. Bobeth, G. Hiller and G. Piranishvili, CP asymmetries in \( \overline{B}\to {{\overline{K}}^{*}}\left( {\to \overline{K}\pi } \right)\overline{\ell}\ell \) and untagged \( {{\overline{B}}_s},{B_s}\to \phi \left( {\to {K^{+}}{K^{-}}} \right)\overline{\ell}\ell \) decays at NLO, JHEP 07 (2008) 106 [arXiv:0805.2525] [INSPIRE].

    ADS  Article  Google Scholar 

  3. [3]

    A. Ali, P. Ball, L. Handoko and G. Hiller, A comparative study of the decays B→(K,K )ℓ+ in standard model and supersymmetric theories,Phys. Rev. D 61 (2000) 074024 [hep-ph/9910221] [INSPIRE].

    ADS  Google Scholar 

  4. [4]

    F. Krüger and J. Matias, Probing new physics via the transverse amplitudes of B 0K ∗0(→ K π+)ℓ+ at large recoil, Phys. Rev. D 71 (2005) 094009 [hep-ph/0502060] [INSPIRE].

    ADS  Google Scholar 

  5. [5]

    LHCb collaboration, Differential branching fraction and angular analysis of the decay B 0K ∗0 μ + μ , Phys. Rev. Lett. 108 (2012) 181806 [arXiv:1112.3515] [INSPIRE].

    Article  Google Scholar 

  6. [6]

    BaBar collaboration, B. Aubert et al., Measurements of branching fractions, rate asymmetries and angular distributions in the rare decays BK+ and BK +, Phys. Rev. D 73 (2006) 092001 [hep-ex/0604007] [INSPIRE].

    ADS  Google Scholar 

  7. [7]

    BELLE collaboration, J.-T. Wei et al., Measurement of the differential branching fraction and forward-backword asymmetry for BK (∗)+, Phys. Rev. Lett. 103 (2009) 171801 [arXiv:0904.0770] [INSPIRE].

    ADS  Article  Google Scholar 

  8. [8]

    CDF collaboration, T. Aaltonen et al., Measurements of the angular distributions in the decays BK (∗) μ + μ at CDF, Phys. Rev. Lett. 108 (2012) 081807 [arXiv:1108.0695] [INSPIRE].

    ADS  Article  Google Scholar 

  9. [9]

    D. Becirevic and E. Schneider, On transverse asymmetries in BK +, Nucl. Phys. B 854 (2012) 321 [arXiv:1106.3283] [INSPIRE].

    ADS  Article  Google Scholar 

  10. [10]

    LHCb collaboration, The LHCb detector at the LHC, 2008 JINST 3 S08005 [INSPIRE].

  11. [11]

    M. Adinolfi et al., Performance of the LHCb RICH detector at the LHC, Eur. Phys. J. C 73 (2013) 2431 [arXiv:1211.6759] [INSPIRE].

    ADS  Article  Google Scholar 

  12. [12]

    R. Aaij et al., The LHCb trigger and its performance in 2011, 2013 JINST 8 P04022 [arXiv:1211.3055] [INSPIRE].

  13. [13]

    T. Sjöstrand, S. Mrenna and P.Z. Skands, PYTHIA 6.4 physics and manual, JHEP 05 (2006) 026 [hep-ph/0603175] [INSPIRE].

    ADS  Article  Google Scholar 

  14. [14]

    I. Belyaev et al., Handling of the generation of primary events in Gauss, the LHCb simulation framework, IEEE Nucl. Sci. Symp. Conf. Rec. (2010) 1155.

  15. [15]

    D. Lange, The EvtGen particle decay simulation package, Nucl. Instrum. Meth. A 462 (2001) 152 [INSPIRE].

    ADS  Article  Google Scholar 

  16. [16]

    P. Golonka and Z. Was, PHOTOS Monte Carlo: a precision tool for QED corrections in Z and W decays, Eur. Phys. J. C 45 (2006) 97 [hep-ph/0506026] [INSPIRE].

    ADS  Article  Google Scholar 

  17. [17]

    GEANT4 collaboration, J. Allison et al., GEANT4 developments and applications, IEEE Trans. Nucl. Sci. 53 (2006) 270.

    ADS  Article  Google Scholar 

  18. [18]

    GEANT4 collaboration, S. Agostinelli et al., GEANT4: a simulation toolkit, Nucl. Instrum. Meth. A 506 (2003) 250 [INSPIRE].

    ADS  Article  Google Scholar 

  19. [19]

    M. Clemencic et al., The LHCb simulation application, Gauss: design, evolution and experience, J. Phys. Conf. Ser. 331 (2011) 032023.

    ADS  Article  Google Scholar 

  20. [20]

    L. Breiman, J.H. Friedman, R.A. Olshen and C.J. Stone, Classification and regression trees, Wadsworth international group, Belmont, California U.S.A. (1984).

  21. [21]

    Y. Freund and R.E. Schapire, A decision-theoretic generalization of on-line learning and an application to boosting, J. Comput. Syst. Sciences 55 (1997) 119.

    MathSciNet  Article  MATH  Google Scholar 

  22. [22]

    LHCb collaboration, Measurement of the fragmentation fraction ratio f s /f d and its dependence on B meson kinematics, JHEP 04 (2013) 001 [arXiv:1301.5286] [INSPIRE].

    Google Scholar 

  23. [23]

    T. Skwarnicki, A study of the radiative cascade transitions between the \( {\varUpsilon^{\prime }} \) and \( \varUpsilon \) resonances, Ph.D. thesis, Institute of Nuclear Physics, Krakow, Poland (1986), DESY-F31-86-02.

  24. [24]

    Particle Data Group collaboration, J. Beringer et al., Review of particle physics, Phys. Rev. D 86 (2012) 010001 [INSPIRE].

    ADS  Google Scholar 

  25. [25]

    BaBar collaboration, B. Aubert et al., Measurement of branching fractions and charge asymmetries for exclusive B decays to charmonium, Phys. Rev. Lett. 94 (2005) 141801 [hep-ex/0412062] [INSPIRE].

    ADS  Article  Google Scholar 

  26. [26]

    C. Bobeth, G. Hiller and D. van Dyk, More benefits of semileptonic rare B decays at low recoil: CP-violation, JHEP 07 (2011) 067 [arXiv:1105.0376] [INSPIRE].

    ADS  Article  Google Scholar 

  27. [27]

    S. Descotes-Genon, T. Hurth, J. Matias and J. Virto, Optimizing the basis of BK + observables in the full kinematic range, JHEP 05 (2013) 137 [arXiv:1303.5794] [INSPIRE].

    ADS  Article  Google Scholar 

  28. [28]

    M. Beneke, T. Feldmann and D. Seidel, Systematic approach to exclusive BV+ , V γ decays, Nucl. Phys. B 612 (2001) 25 [hep-ph/0106067] [INSPIRE].

    ADS  Article  Google Scholar 

  29. [29]

    B. Grinstein and D. Pirjol, Exclusive rare BK + decays at low recoil: controlling the long-distance effects, Phys. Rev. D 70 (2004) 114005 [hep-ph/0404250] [INSPIRE].

    ADS  Google Scholar 

  30. [30]

    M. Beylich, G. Buchalla and T. Feldmann, Theory of BK (∗)+ decays at high q 2 : OPE and quark-hadron duality, Eur. Phys. J. C 71 (2011) 1635 [arXiv:1101.5118] [INSPIRE].

    ADS  Article  Google Scholar 

  31. [31]

    A. Khodjamirian, T. Mannel, A. Pivovarov and Y.-M. Wang, Charm-loop effect in BK (∗)+ and BK γ,JHEP 09 (2010) 089[arXiv:1006.4945] [INSPIRE].

    ADS  Article  Google Scholar 

  32. [32]

    P. Ball and R. Zwicky, B d,s → ρ, ω, K , 𝜙 decay form-factors from light-cone sum rules revisited, Phys. Rev. D 71 (2005) 014029 [hep-ph/0412079] [INSPIRE].

    ADS  Google Scholar 

  33. [33]

    U. Egede, T. Hurth, J. Matias, M. Ramon and W. Reece, New observables in the decay mode \( {{\overline{B}}_d}\to {{\overline{K}}^{*0 }}{\ell^{+}}{\ell^{-}} \), JHEP 11 (2008) 032[arXiv:0807.2589] [INSPIRE].

    ADS  Article  Google Scholar 

  34. [34]

    S. Jäger and J. Camalich, On BV ℓℓ at small dilepton invariant mass, power corrections and new physics, JHEP 05 (2013) 043 [arXiv:1212.2263] [INSPIRE].

    Article  Google Scholar 

  35. [35]

    BaBar collabortation, B. Aubert et al., Ambiguity-free measurement of cos 2β: Time-integrated and time-dependent angular analyses of BJ/ψ Kπ, Phys. Rev. D 71 (2005) 032005 [hep-ex/0411016] [INSPIRE].

    ADS  Google Scholar 

  36. [36]

    G.J. Feldman and R.D. Cousins, A unified approach to the classical statistical analysis of small signals, Phys. Rev. D 57 (1998) 3873 [physics/9711021] [INSPIRE].

    ADS  Google Scholar 

  37. [37]

    B. Sen, M. Walker and M. Woodroofe, On the unified method with nuisance parameters, Statistica Sinica 19 (2009) 301.

    MathSciNet  MATH  Google Scholar 

  38. [38]

    LHCb collaboration, Measurement of the CP asymmetry in B 0K ∗0 μ + μ decays, Phys. Rev. Lett. 110 (2013) 031801 [arXiv:1210.4492] [INSPIRE].

    Article  Google Scholar 

  39. [39]

    BaBar collaboration, B. Aubert et al., Measurement of decay amplitudes of BJ/ψK ,ψ(2S)K and χ c1 K with an angular analysis,Phys. Rev. D 76 (2007) 031102 [arXiv:0704.0522] [INSPIRE].

    ADS  Google Scholar 

  40. [40]

    LHCb collaboration, Differential branching fraction and angular analysis of the decay \( B_s^0\to \phi {\mu^{+}}{\mu^{-}} \), JHEP 07 (2013) 084 [arXiv:1305.2168] [INSPIRE].

    Google Scholar 

  41. [41]

    C.-D. Lu and W. Wang, Analysis of \( B\to K_j^{*}\left( {\to K\pi } \right){\mu^{+}}{\mu^{-}} \) in the higher kaon resonance region, Phys. Rev. D 85 (2012) 034014 [arXiv:1111.1513] [INSPIRE].

    ADS  Google Scholar 

  42. [42]

    D. Becirevic and A. Tayduganov, Impact of \( B\to K_0^{*}{\ell^{+}}{\ell^{-}} \) on the New Physics search in BK + decay,Nucl. Phys. B 868 (2013) 368[arXiv:1207.4004] [INSPIRE].

    ADS  Article  Google Scholar 

  43. [43]

    T. Blake, U. Egede and A. Shires, The effect of S-wave interference on the B 0K ∗0+ angular observables, JHEP 03 (2013) 027 [arXiv:1210.5279] [INSPIRE].

    ADS  Article  Google Scholar 

  44. [44]

    J. Matias, On the S-wave pollution of BK + observables, Phys. Rev. D 86 (2012) 094024 [arXiv:1209.1525] [INSPIRE].

    ADS  Google Scholar 

  45. [45]

    B. Efron, Bootstrap methods: another look at the jackknife, Ann. Statist. 7 (1979) 1.

    MathSciNet  Article  MATH  Google Scholar 

  46. [46]

    C. Bobeth, G. Hiller, D. van Dyk and C. Wacker, The decay BK+ at low hadronic recoil and model-independent ΔB = 1 constraints, JHEP 01 (2012) 107 [arXiv:1111.2558] [INSPIRE].

    ADS  Article  Google Scholar 

  47. [47]

    M. Beneke, T. Feldmann and D. Seidel, Exclusive radiative and electroweak bd and bs penguin decays at NLO, Eur. Phys. J. C 41 (2005) 173 [hep-ph/0412400] [INSPIRE].

    ADS  Article  Google Scholar 

  48. [48]

    A. Ali, G. Kramer and G.-h. Zhu, BK ++ decay in soft-collinear effective theory, Eur. Phys. J. C 47 (2006) 625 [hep-ph/0601034] [INSPIRE].

    ADS  Article  Google Scholar 

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