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Exclusive rare B (s,c) decays in light-front quark model

Exclusive rare B (s,c) decays in light-front quark model. Ho-Meoyng Choi (Kyungpook Nat’l Univ.). Based on: PRD 81, 054003(2010) JPG 37, 085005(2010). Outline. Motivation Rare B (s,c) decays Why Light-Front?

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Exclusive rare B (s,c) decays in light-front quark model

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  1. Exclusive rare B(s,c) decays in light-front quark model Ho-Meoyng Choi (Kyungpook Nat’l Univ.) Based on: PRD 81, 054003(2010) JPG 37, 085005(2010) Outline • Motivation • Rare B(s,c) decays • Why Light-Front? • 4. Light-front quark model(LFQM) calculation of rare B(s,c) decays • -Bc D(s)l+l-and Bs (K,η,η’)l+l- • 5. Conclusion APFB2011, Seoul, Korea, Aug 22~26

  2. 1. Motivation Exclusive heavy meson decays provides useful testing ground of SM and beyond SM: Experiment: easy to access (LHCb, Barbar, Belle etc.) Theory: difficult to understand due to the nonperturbative hadronic form factors Theoretical uncertainty! In our previous work, we have analyzed (I) (P,V) ln , (II) P  (P,V)ln , (III) V  Pg, (IV) B  Kl+l- decays using Light-Front Quark Model(LFQM)[PLB 460,461(99), PRD 80, 054016(09) , NPA 856, 95 (11), PLB 696, 518(11) by Choi & Ji; PRD75, 073016(07) by Choi; PRD 65, 074032(02) by Choi, Ji, Kisslinger] To extend the applicability of our LFQM, we thus investigate Bc D(s)l+l-and Bs (K,η,η’)l+l- decays

  3. 2. Semileptonic rare Bq F(d,s) (l+l–, ν ν)decays 1) In SM: Z(γ)-Penguin and W-Box l (ν) l (ν) s(d) b Flavor Changing Neutral Current(FCNC) 2) Beyond SM : New heavy particles q Bq Fs(d) Transition amplitude for Bq F: Aim to compute Short distance(SD) contribution Long distance(LD) contribution

  4. 3. Why Light-Front? Equal t Equal t

  5. Energy-Momentum Dispersion Relation Equal t (Instant form) Equal t (Front form) k1 k1+ k2+ k2 k3+ k3 t Not allowed ! since k+>0 t k1+ + k2+ + k3+=0 k1+k2+k3=0

  6. Covariant vs. time-ordered diagram LF nonvalence LF valence Usually, LF nonvalence contribution vanishes as q+ 0 LF Zero-mode = nonvanishing LF nonvalence as q+ 0

  7. 4. Light-Front Quark Model PRD59, 074015(99); PLB460, 461(99) by Choi and Ji Key idea of our LFQM: Using the variational principle to the QCD-motivated effective Hamiltonian, we fix the model parameters! Variational Principle radial spin-orbit PRD80,054016(09)

  8. Experiment Linear potential Harmonic oscillator (HO)potential Input masses Optimized model parameters(in unit of GeV) and meson mass spectra

  9. q2=-Q2 x,k^ x,k^- q^ yf yi analytic continuation f(Q2) f(q2) (in spacelike) (in timelike) LFQM calculation of LD contributions to Bq → F decays P=P1+P2 q= P1-P2 Calculational Method: In q+=q0+q3=0 frame where q2= -q^2=-Q2: f(+,-,T) ≈ ò[dx][d2k^] y*f(x,k^+(1-x)q^) yi(x,k^) P2 P1

  10. Bs (K,η,η’)l+l-

  11. Non-resonant branching ratio (in units of 10-7) Bs Kτ+τ- Bs Kμ+μ- Bs Kνν B  K[PRD 65, 074032(02)]

  12. Bs (K,η,η’)l+l- JPG 37, 085005(10) by Choi

  13. Bc D(s)l+l- Bc Dsμ+μ- Bc Dsτ+τ- PRD 81, 054003(10) by Choi

  14. Lepton Polarization Asymmetry(LPA): Bs ημ+ μ- Bs ητ+ τ-

  15. 5. Conclusions 1. Study exclusive rare Bc D(s)l+l-and Bs (K,η,η’)l+l- decays within the SM and LFQM: - Our model parameters obtained from the variational principle uniquely determine the processes - LF covariant form factors f+, f-, fT are obtained in q+=0 frame (Effective inclusion of zero-mode to f- was made in the valence region) - Computed BR and LPA and compared with other models - Bs (η,η’)may help in determining the η-η’ mixing angle 2. Future work: - Extend the present work to include more processes such as PV

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