Measurements of CP violating phases in B decays at LHCb

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1 Measurements of CP violating phases in B decays at Sevda Esen [Heidelberg University] on behalf of the collaboration Les Rencontres de Physique de la Vallée d Aoste, 1-7 March 215

2 CP Violation in the SM Source of CPV: the complex phase in the CKM matrix ( ) ( Vud V us V ub V cd V cs V cb V td V ts V tb Unitarity requirements: Σ i V ij V ik = δ jk V ud Vub + V cdvcb + V tdvtb = V us Vub + V csvcb + V tsvtb = 1 λ 2 /2 λ Aλ 3 (ρ iη) λ 1 λ 2 /2 Aλ 2 Aλ 3 (1 ρ iη) Aλ 2 1 ) Wolfenstein, PRL 51, 1945 (1983) η excluded area has CL >.95 sin 2β γ α ρ CKM f i t t e r Summer 14 sol. w/ cos 2β < (excl. at CL >.95).1 α γ β α Check consistency of the CKM framework: measure three angles and two sides of the UT search for potential new physics contributions S. Esen / Heidelberg University CPV in La Thuile / 17

3 (1) CPV in decay: (2) CPV in mixing P(B f ) P( B f ) P(B B) P( B B) Mass eigenstates: B H = p B q p/q 1 B B L = p B + q B CPV New J. Phys. 15 (213) 5321 (3) CPV in the interference of decay and mixing P(B f CP ) P(B B f CP ) λ = q Ā( B f CP ) p A(B f CP ) φ f q = arg(η f λ f ) = φ M 2φ D φ M B φ D s S. Esen / Heidelberg University CPV in La Thuile / 17 B s φ D f

4 Theoretical time dependent CP asymmetry A CP (t) = Γ( B q f ) Γ(B q f ) Γ( B q f )+Γ(B q Experimentally Adir CP = cos( Mqt)+Amix CP sin( Mqt) f ) cosh( Γ qt/2)+a Γ sinh( Γ qt/2) A CP (1 2w)e 1 2 m2 s σ2 t A theory CP w Probability of getting the initial flavor wrong σ t Decay time resolution η f CP eigenvalue angular analysis Minimum requirements: excellent decay time resolution 4 5 fs good flavor tagging Effective tagging power: 3 4% large statistics trigger efficiencies: 9 % for dimuon channels track reconstruction efficiency: > 96 % for long tracks for negligible penguin contr. A dir A mix CP CP C η f sin φ q S for B s : φ s and λ for B : C and S S. Esen / Heidelberg University CPV in La Thuile / 17

5 B s J/ψK + K PRL 114, 4181 SM prediction: φ s = (.36 ±.2)rad and λ 1 Signal: 9569±35 events 4d fit in bins of m KK : decay time and angles in helicity frame Results φ s [rad].58 ±.49 ±.6 λ.964 ±.19 ±.7 Candidates / (.2 ps) Decay time [ps] Candidates / (.5π rad) ϕ h [rad] Candidates / Candidates / cosθ µ cosθ K CP-even - - CP-odd S-wave total S. Esen / Heidelberg University CPV in La Thuile / 17

6 B s J/ψK + K : Polarization dependence PRL 114, 4181 For non-negligible penguin contributions size of pollution could be different for 3 P-wave and the S-wave states CPV might be polarization dependent complicates the search for NP effects e.g.,bhattacharya, Datta, Int. J. Mod, Phys. A28(213) We measure: Ā f A f λ f = q p = λ f e iφf s for each f =,,, S assume zero CPV in mixing PLB 728, (214) 67 φ s [rad].45 ±.53 ±.7 φ s φ s [rad].18 ±.43 ±.9 φ s φ s [rad].14 ±.35 ±.6 φ S s φ s [rad].15 ±.61 ±.21 λ 1.12 ±.58 ±.13 λ /λ 1.2 ±.12 ±.5 λ /λ.97 ±.16 ±.1 λ S /λ.86 ±.12 ±.4 S. Esen / Heidelberg University CPV in La Thuile / 17

7 B s J/ψπ + π Phys. Lett. B 736 (214) ± 2 signal events 6 dimensional fit: m ππ, m J/ψππ, decay time decay angles in helicity frame Events/ (2 MeV) Data Fit Signal Background f (98) f 2 (1525) f 2 (127) f (15) f (179) NR B J/ψπ + π from the amplitude analysis 2.3% CP 95% CL 1 largest component f (98) m(π + π ) [GeV] S. Esen / Heidelberg University CPV in La Thuile / 17

8 B s J/ψπ + π Phys. Lett. B 736 (214) 186 SM prediction: φ s = (.36 ±.2)rad and λ ± 2 signal events Results φ s [rad].7 ±.68 ±.8 λ.89 ±.5 ±.1 Combinations/ (.1 ps) Total Signal Backg Decay time [ps] 5 S. Esen / Heidelberg University CPV in La Thuile / 17

9 φ s - Γ s world average.14 Dfl 8fb CDF 9.6 fb 1 CMS 2 fb 1 68% CL contours ( ) 3fb 1 ATLAS 4.9 fb SM Combined S. Esen / Heidelberg University CPV in La Thuile / 17

10 B J/ψK S NEW ) 2 Candidates / ( 1 MeV/c precise measurement of sin(2β) mostly by B-factories so far update with 3fb 1 - increased data set - improved flavor tagging signal: 4156 ± 27 preliminary (MeV/c ) m J ψ/ K S BaBar PRD 79 (29) 729 BaBar χ c K S PRD 8 (29) 1121 BaBar J/ψ (hadronic) K S PRD 69 (24) 521 Belle PRL 18 (212) ALEPH PLB 492, 259 (2) OPAL EPJ C5, 379 (1998) CDF PRD 61, 725 (2) PLB 721 (213) 24 Belle5S PRL 18 (212) Average HFAG sin(2β) sin(2φ 1 ) H F A G Moriond 214 PRELIMINARY.69 ±.3 ±.1.69 ±.52 ±.4 ± ±.42 ± ±.2 ± ± ± ±.7 ±.4.57 ±.58 ±.6.68 ± S. Esen / Heidelberg University CPV in La Thuile / 17

11 B J/ψK S NEW Preliminary C =.38 ±.32 ±.5 S =.731 ±.35 ±.2 Candidates / (.2 ps ) preliminary consistent with current WA and the SM precision similar to B factories more details by Frank Meier on Wednesday at YSF Signal yield asymmetry t (ps) t (ps) S. Esen / Heidelberg University CPV in La Thuile / preliminary

12 Penguin Pollution in φ q What we really measure: φ q = φ SM + δφ NP + δφ pen B d(s) b Colour Singlet Exchange u, c, t W c c s(d) J/ψ K S - doubly Cabibbo suppressed d(s) - non-perturbative hadronic enhancements? d(s) Control penguins via flavor symmetry: R. Fleischer, Eur. Phys. J. C 1, 299 (1999) use U-spin-related modes with increased relative penguin influence ex: B s J/ψK S, B s J/ψK, B J/ψρ, B J/ψπ to be published soon ongoing analysis Phys.Lett. B742 (215) can extract δφ pen need to take into account SU(3) breaking S. Esen / Heidelberg University CPV in La Thuile / 17

13 B s J/ψK S ) Candidates / ( 2 MeV/c 2 Pull Preliminary B Downstream K S B s A Γ = ±.6 C =.28 ±.41 ±.8 S =.8 ±.4 ±.8 preliminary (MeV/c 2 ) m J/ψ KS S. Esen / Heidelberg University CPV in La Thuile / 17 K S split into two categories: Long and Downstream Signal Bs Yield: 37 ± 2 Long and 61 ± 3 Downstream Candidates / (.15 ps ) Pull preliminary 3 1 Downstream K S more details by Frank Meier on t (ps) Wednesday at YSF

14 γ from B Decays Can be determined entirely from tree decays typical decays are B Dh: interference between D and D contributions small theoretical uncertainty ( γ/γ 1 6 ) A B α A f + r B e i(δ B γ)ā f Amplitude ratio: r B = A(B DK) / A(B DK) Strong phase difference: δ B Several methods: GSW, ADS, GSGZ... S. Esen / Heidelberg University CPV in La Thuile / 17

15 Combination Measurements considered in combination: robust combination: Decay Method Data B + D( hh)h + GLW/ADS 1 fb 1 B + D( Kπππ)h + ADS 1 fb 1 B + D( KS hh)k + GGSZ 3 fb 1 B + D( KS Kπ)K + GLS 3 fb 1 B D( hh)k GLW/ADS 3 fb 1 Bs D s ± K time-dependent 1 fb 1 only B DK-like channels γ = full combination: + B Dπ-like channels γ = more details by Rose Koopman on Tuesday at YSF S. Esen / Heidelberg University CPV in La Thuile / 17

16 Summary I Precision measurements of CP violating phases at Updated measurements of B B mixing phases [3 fb 1 ] - experimental sensitivity σ(φ s ) <.38 - first polarization dependent φ s measurements - sin(2β) competitive precision with Belle and Babar good prospects for run II - limits on penguin contributions precise measurement of γ through combination S. Esen / Heidelberg University CPV in La Thuile / 17

17 Summary II good agreement with the SM overall, but not the end of the story... S. Esen / Heidelberg University CPV in La Thuile / 17

18 BACKUP S. Esen / Heidelberg University CPV in La Thuile / 17