Semileptonic and leptonic B/Bs decays

Semileptonic and leptonic B/Bs decays Christoph Schwanda Ins$tute of High Energy Physics Austrian Academy of Sciences 7th Belle PAC Mee7ng 2013 March 10-­‐11, 2013, KEK, Tsukuba, Japan Overview •  Determina7on of |Vcb| and |Vub| B → X (e,µ,τ) ν B → (e,µ,τ) ν
–  Precise measurement of SM parameters –  Test of the CKM mechanism •  Search for physics beyond the SM –  Right-­‐handed currents not in loops –  NP scenarios with extended Higgs sector March 11, 2013 Christoph Schwanda 2 |Vcb| from exclusive decays B → D*lν
B → Dlν
•  Theory input: Form factors F(1) and G(1) at zero recoil (w=1) from laZce QCD calcula7ons •  Experimental method: Measure the differen7al width dΓ as a func7on of w and extrapolate to zero recoil (typically assuming a parameteriza7on of the form factors) March 11, 2013 Christoph Schwanda 3 |Vcb| from inclusive decays B → Xlν
•  Based on the Operator Product Expansion (OPE) •  <Oi>: hadronic matrix elements (non-­‐perturba7ve) ci: coefficients (perturba7ve) •  Parton-­‐hadron duality → the hadronic ME depend only on the ini7al state •  We can determine the hadronic ME from other observables in inclusive B decays (moments of El and M2X) → global fit Kine7c scheme [JHEP 1109 (2011) 055] 1S scheme [PRD70, 094017 (2004)] O(1) mb, mc mb O(1/m2b) µ2π, µ2G λ1, λ2 O(1/m b) ρ3D, ρ3LS Christoph Schwanda ρ1, τ1-­‐3 3
March 11, 2013 4 |Vcb| Exclusive (D*lν)
|Vcb| = (39.54 +/-­‐ 0.50exp +/-­‐ 0.74th) x 10-­‐3
Inclusive (kine7c)
|Vcb| = (41.88 +/-­‐ 0.73) x 10-­‐3
HFAG preprint [arXiv:1207.1158] •  Exclusive and inclusive agree at the level of ~2 sigma March 11, 2013 Christoph Schwanda 5 Determina7on of |Vub| Exclusive B → πlν
•  Form factor f+ from laZce QCD [PRD73, 074502; PRD79, 054507] or from QCD sum rules [PRD83, 094031; PRD 71, 014015] Inclusive B → Xulν
March 11, 2013 •  Also based on the OPE [NPB699, 335; JHEP01, 097; JHEP10, 058] •  Experimental selec7ons can comprise the convergence of the OPE → shape func7on Christoph Schwanda 6 |Vub| Exclusive (BCL fit)
|Vcb| = (3.23 +/-­‐ 0.30) x 10-­‐3
Inclusive (BLNP)
|Vcb| = (4.40 +/-­‐ 0.15exp +/-­‐ 0.20th) x 10-­‐3
HFAG preprint [arXiv:1207.1158] •  Exclusive and inclusive agree at the level of ~3 sigma March 11, 2013 Christoph Schwanda 7 Unitarity triangle Average |Vub| used by CKM firer (ICHEP 2012)
|Vub| = (3.75 +/-­‐ 0.29) x 10-­‐3
UT fit result
|Vub| = (3.49 +0.21/-­‐0.09) x 10-­‐3
•  Exclusive/inclusive average nicely fits SM •  However, given the exclusive/inclusive discrepancy, there is clearly room for NP in the UT March 11, 2013 Christoph Schwanda 8 Right-­‐handed currents •  Add right-­‐handed currents (|Vub|=|VubL|) –  B → πlν goes as |VubL+VubR|2 –  B → τν goes as |VubL-­‐VubR|2 –  B → Xulν goes as |VubL|2+|VubR|2 •  Can fit the data with ~17% RHC contribu7on Florian Bernlochner CKM 2012 workshop March 11, 2013 Christoph Schwanda 9 Search for the charged Higgs in B → τν
H-
SM 2HDM Type II W.S.Hou, PRD 48, 2342 (1993) •  SM expecta7on –  Br(B → τν) = (1.20 +/-­‐ 0.25) x 10-­‐4 •  UT fit result –  Br(B → τν) = (0.72 +0.12/-­‐0.08) x 10-­‐4 March 11, 2013 (10-­‐4) Christoph Schwanda 10 2HDM Type II effect in B → D(*)τν
•  Observables –  R(D*) = Br(D*τν)/Br(D*lν) –  R(D) = Br(Dτν)/Br(Dlν) BaBar [PRL 109, 101802]
Belle D(*)τν average
March 11, 2013 Christoph Schwanda 11 B → D**lν mystery Sascha Turczyk CKM 2012 workshop March 11, 2013 Christoph Schwanda •  Inclusive-­‐exclusive gap of (1.45 +/-­‐ 0.29)% •  1/2 vs. 3/2 puzzle •  Belle II might clarify the situa7on by measuring B → D(*)nπlν
12 New Belle hadronic tag •  New hadronic tag based on Neurobayes •  2-­‐3x sta7s7cal gain over previous analyses March 11, 2013 Christoph Schwanda 13 CABIBBO FAVORED DECAYS March 11, 2013 Christoph Schwanda 14 B → D(*)sKlν
[PRD 86, 072007 (2012)] •  657 million BB events •  Simultaneous measurement of DsK and D*sK modes •  6σ sigma significance for Ds and D*s combined Ds sample
D*s sample
March 11, 2013 Christoph Schwanda 15 Bs → Xlν inclusive semileptonic Submired to PRD •  121/t Belle Y(5S) data •  Tag Bs decays with a fully reconstructed Ds •  Measure same sign Ds-­‐l-­‐ rela7ve to the number of Ds •  Bu,d contamina7on es7mated using PDG parameters March 11, 2013 Christoph Schwanda 16 Bs → Xlν inclusive semileptonic Ds-­‐ sample
R = N(Ds-­‐l-­‐)/N(Ds-­‐)
March 11, 2013 Ds-­‐e-­‐ sample
Submired to PRD Ds-­‐µ-­‐ sample
Br(Bs → Xlν)
Christoph Schwanda 17 B → D(*)Xlν with hadronic tag Shown at ICHEP 2012 •  703/t Belle Y(4S) data •  Second B meson fully reconstructed (hadronic tag) •  Charmed meson reconstructed •  Secondary and fake lepton bkg. subtracted from a fit to lepton momentum •  Signals extracted from a 2d fit to Mbc and MD (D modes) and Mbc and Δm (D* modes) March 11, 2013 Christoph Schwanda 18 B → D(*)Xlν with hadronic tag Shown at ICHEP 2012 B0 → D0lνX
Br
March 11, 2013 •  Results compared to current HFAG/PDG expecta7on Christoph Schwanda 19 CABIBBO SUPPRESSED DECAYS March 11, 2013 Christoph Schwanda 20 B → πlν with hadronic tag Shown at Lake Louise 2012 •  703/t of Belle Y(4S) data •  Hadronic tag •  Yield extracted from M2miss in 13 (7) bins of q2 for B0 → π+lν (B+ → π0lν) March 11, 2013 Christoph Schwanda 21 B → ρlν with hadronic tag Shown at Lake Louise 2012 •  703/t of Belle Y(4S) data •  Hadronic tag •  Yield extracted from M2miss in 11 (6) bins of q2 for B+ → ρ0lν (B0 → ρ+lν) March 11, 2013 Christoph Schwanda 22 B+ → ωlν and B+ → η(‘)lν
Shown at Lake Louise 2012 •  703/t of Belle Y(4S) data •  Soon to be submired to Phys. Rev. D March 11, 2013 Christoph Schwanda 23 Evidence for B → pplν
• 
• 
• 
• 
Shown at Moriond EW 2013 703/t Y(4S) data Hadronic tag Detailed study of proton id Signal extracted from M2miss March 11, 2013 Christoph Schwanda 24 LEPTONIC AND/OR RARE DECAYS March 11, 2013 Christoph Schwanda 25 Leptonic B decays •  Helicity suppression Γ(eν) << Γ(µν) << Γ(τν) •  Very clean theore7cally, might be affected by NP (2HDM, lepto-­‐quark) •  B → eν and B → µν are also experimentally clean but beyond the reach of Belle •  B → τν has 2-­‐3 neutrinos in the final state and kinema7cs cannot be fully reconstructed even with hadronic tagging (high background measurement) March 11, 2013 Christoph Schwanda 26 Search for B → lν
Shown at ICHEP 2012 •  703/t of Y(4S) data •  Hadronic tag •  Limits extracted from lepton momentum distribu7on e
March 11, 2013 Christoph Schwanda µ
27 Measurement of B → τν
• 
• 
• 
• 
To appear in Phys. Rev. Ler. 703/t of Y(4S) data 4 signal tau modes: τ → eνν, µνν, πν, ρν
New hadronic tag (sample x3 compared to 2006 analysis) 2d fit to EECL and M2miss (2006: EECL only) –  Improve sensi7vity by 20% –  More robust against peaking backgrounds March 11, 2013 Christoph Schwanda 28 Measurement of B → τν To appear in Phys. Rev. Ler. •  Simultaneous fit to all four tau modes •  Signal yield: 62 +23/-­‐22 +/-­‐ 6 (3σ including systema7cs) •  Br(B → τν) = (0.72 +0.27/-­‐0.25 +/-­‐ 0.11) x 10-­‐4 [arXiv:1208.4678, to appear in PRL] March 11, 2013 Christoph Schwanda 29 Measurement of B → τν
To appear in Phys. Rev. Ler. •  Consistency between tau modes March 11, 2013 Christoph Schwanda 30 SUMMARY March 11, 2013 Christoph Schwanda 31 Summary of recent Belle results Cabibbo favored decays •  Evidence for B-­‐ → Ds+K-­‐l-­‐ν
Br(B → D(*)sKlν) = (0.59 +/-­‐ 0.12stat +/-­‐ 0.15syst) x 10-­‐3 •  Measurement of Bs → Xslν
Br(Bs → Xln) = (10.6 +/-­‐ 0.5stat +/-­‐ 0.4syst +/-­‐ 0.6ext)% •  Measurement of B → D(*)Xlν
8 semi-­‐inclusive BRs are measured Cabibbo suppressed decays •  Exclusive decays B → Xulν and extrac7on of |Vub| Br(B0 → π-­‐lν) = (1.49 +/-­‐ 0.09stat +/-­‐ 0.07syst) x 10-­‐4 Br(B+ → π0lν) = (0.80 +/-­‐ 0.08stat +/-­‐ 0.04syst) x 10-­‐4 B → ρ0lν, ρ+lν, ωlν, η(‘)lν also measured q2 distribu7ons are obtained March 11, 2013 Christoph Schwanda 32 Summary of recent Belle results Cabibbo suppressed decays •  First evidence for B → pplν Br(B → pplν) = (5.78 +2.42/-­‐2.13 +/-­‐ 0.86) x 10-­‐6 Leptonic/rare •  Search for B → lν with hadronic tag Br(B → eν) < 3.5 x 10-­‐6 at 90% C.L. Br(B → µν) < 2.5 x 10-­‐6 at 90% C.L. •  Measurement of B → τν with hadronic tag Br(B → τν) = (0.72 +0.27/-­‐0.25 +/-­‐ 0.11) x 10-­‐4 (3.0 σ) Belle average: (0.96 +/-­‐ 0.26) x 10-­‐4 (4.0 σ) March 11, 2013 Christoph Schwanda 33