Rencontres de Blois 2014

Transcription

1 Rencontres de Blois 14 Hadronic b decays and the Unitarity triangle angle γ at Jeremy alseno on behalf of the collaboration J.alseno [at] bristol.ac.k May 14 Hadronic b decays and the Unitarity triangle angle γ at 1

2 Otline 1. B ± [ π π ] ±. B ± [ ± π ± ] ± 3. B c J/ψ3π π 4. Λ b pπ φ 3 = γ arg( Vd V b V cd V cb α V d V* b V td V* tb γ β V cd V* cb Hadronic b decays and the Unitarity triangle angle γ at

3 γ from B ecays Theoretically cleanest tandard Model measrement of γ from B decays δγ O(1 7 from electroweak corrections: J. Brod and J. Zpan, JHEP 141 (14 1 When and decay to the same final state, f Interference between the dominant b cūs with the corresponding C b cs - B b A B A f V cb W V s s c - r B e i(δ Bγ Ā f - B V b b W V cs c s - Amplitde ratio: r B = A(B A(B trong phase difference between A(B and A(B : δ B Hadronic b decays and the Unitarity triangle angle γ at 3

4 GGZ Method Measre r B, δ B and γ, throgh interference in the alitz plot of decays to CP eigenstates A. Bondar, Proceedings of BINP pecial Analysis Meeting on alitz Analysis, 4-6 ep., npblished A. Giri, Y. Grossman, A. offer, J. Zpan, Phys. Rev. 68 (3 418 eg. π π and π π alitz plots defined as scatterplot of m ( π vs m ( π Contains complete qantm information of the decay inclding phase relationships A(B = A r B e i(δ Bγ A r B e i(δ Bγ Hadronic b decays and the Unitarity triangle angle γ at 4

5 B ± [ π π ] ± First model-dependent measrement of γ from sing the GGZ method Integrated data sample of 1 fb 1 recorded at centre-of-mass energy of 7 TeV e to the long lifetime, data divided in depending on reconstrction Long : Pion tracks located within the silicon verte detector ownstream : decayed beyond the silicon verte detector Most dangeros backgrond is B ± [ π π ]π ± where π ± was misidentified as ± Ecellent RICH PI performance spresses this by O(1 for minimal signal loss Partially reconstrcted backgronds Mostly contains real [ π π ] decays, bt involve processes with additional particles eg. B ± ρ ±, B ± h ± where h = or π Combinatorial pressed by B candidate displacement from primary pp interaction verte Hadronic b decays and the Unitarity triangle angle γ at

6 Yield Etraction Analysis performed in stages etermine signal yield from fit to the B ± candidate mass Gives the signal and backgrond fractions for the sbseqent alitz analysis Perform fit simltaneosly with control sample B ± [ π π ]π ± Candidates / ( 1 MeV/c (a Long Long Preliminary ± ± B Cross-feed from ± ± B π Partiallyreconstrcted backgrond m, inclding combinatoric backgrond m B [MeV/c ] Candidates / ( 1 MeV/c ownstream 14 ± ± (a Preliminary B Cross-feed from 1 ± ± B π 1 ownstream Partiallyreconstrcted 8 backgrond m, inclding 6 combinatoric backgrond m B [MeV/c ] B ± ± yield: 17 ± 17 events B ± ± yield: 4 ± 7 events Hadronic b decays and the Unitarity triangle angle γ at 6

7 alitz Amplitde Amplitde model fied to that determined by the BaBar Collaboration P. del Amo anchez et al. (BaBar Collab., Phys. Rev. Lett. 1 ( Restrict fit region to 3σ arond B mass γ manifests as a difference in the strctre between these alitz plots B B Candidates / (.6 GeV /c 4 ] 4 /c [GeV - m [GeV /c ] m m- (GeV Candidates / (.6 GeV /c 4 Candidates / (.18 GeV /c Preliminary m [GeV /c 4 ] m [GeV /c 4 ] Candidates / (.6 GeV /c 4 ] 4 /c [GeV - m [GeV /c ] m 1 m- [GeV /c 4 ] Candidates / (.6 GeV /c 4 Candidates / (.18 GeV /c Preliminary - 1 m [GeV /c 4 ] m [GeV /c 4 ] Hadronic b decays and the Unitarity triangle angle γ at 7

8 Reslts y±.3 Technical detail: Instead of fitting for rb, δb and γ directly. B Likelihood.1 contors Fit for transformed parameters -.1 ± rb cos(δb ± γ B δb[ ] y± rb sin(δb ± γ 3 Preliminary ± 3 Preliminary Reslts =.84 ±.4 ±.9 ± y =.3 ±.48 ±.9 ±.7.8 ±.3 y =.13 ±.48.6 Uncertainties 1: statistical, : systematic, 3: model Convert to γ, negligible miing effect ry in a 1 Pr el im ±.1 rb =.7 ± γ [ ] γ [ ] Residal confidence level Hadronic b decays and the Unitarity triangle angle γ at 8

9 Reslts : 1 fb 1 Preliminary Reslts γ = ( Belle: 67M B B pairs PR 81 (1 11 γ = ( Incldes B ( BaBar: 468M B B pairs PRL 1 ( γ = (68 ± 1 Incldes B ( ( Incldes There are also model-independent binned alitz measrements with inpt from CLEO J. Libby et al. (CLEO Collab. Phys. Rev.. 8 (1 116 : 1 fb 1 Belle: 77M B B pairs PLB 718 (1 43 γ = ( Incldes PR 8 ( γ = (77 ± 16 γ soltion consistent with tandard Model chosen Uncertainties comparable Hadronic b decays and the Unitarity triangle angle γ at 9

10 A-Like Adaptation - B b Color-favored V cb W V s s c - - B Color-sppressed V b b ifference in magnitdes mean that reslting asymmetries tend to be small, however (89 from spectator (sppressed c V cs W V s s s - * W V cs (89 from W (favored Amplitdes of similar magnitde can enhance the effect of CP asymmetries. Atwood, I. nietz, A. oni, Phys. Rev. Lett. 78 ( c Hadronic b decays and the Unitarity triangle angle γ at 1 V cs W V s s s c s - * -

11 A Method ingly Cabibbo ppressed (C decays across the alitz plot Y. Grossman, Z. Ligeti and A. offer, Phys. Rev 67 ( Consider B followed by π For a given B charge, possibilities for kaon charge configration Charged kaons with Opposite ign (O Γ O r B r r B r κ f cos(δ B γ δ f Charged kaons with ame ign ( Γ 1 r B r r B r κ f cos(δ B γ δ f Amplitde ratio: r = A( π A( π 3-body decay, so resonant strctre varies across the alitz plot, m vs m π ecay rate in region of a resonance depends on integral of the interference term in that region Coherence factor κ f, and average strong phase difference δ f Hadronic b decays and the Unitarity triangle angle γ at 11

12 A Method κ f e iδ f A π (m, m πa π (m, m πdm dm π π and π are flavor non-specific final states Correlated pairs can tag the flavor Amplitdes measred by the CLEO Collaboration J. Insler et al. (CLEO Collab. Phys. Rev.. 8 (1 916 Hadronic b decays and the Unitarity triangle angle γ at 1

13 Reslts World s first measrement of γ sing C π decays Fll data sample of 3 fb 1 : 1 fb 7 TeV and fb 8 TeV R. Aaij et al. ( Collab. Phys. Lett. B 733 (14 36 Γ O r B r rbrκf cos(δbγ δf Γ O r B r rbrκf cos(δbγ δf B [ ] (g Entries / (1 MeV/c B [ π ] (e 3 π 3 m, incl. combinatorics m, incl. combinatorics ignal ignal Mis-I Mis-I Partially reconstrcted Partially reconstrcted 1 1 Entries / (1 MeV/c [MeV/c ] [MeV/c ] π ] ] π m([ m([ γ manifests as a difference in the rates when kaons have opposite charge Hadronic b decays and the Unitarity triangle angle γ at 13

14 Reslts γ constraint acconting for miing effects, contors represent change in likelihood Whole alitz plot (89 region r B.3 r B (a γ nσ contors with n = 1 (dark ble, n = (medim ble and n = 3 (light ble ata point: average from other B modes R. Aaij et al. ( Collab. Phys. Lett. B 76 (13 11 Agreement within σ Constraint tighter in (89 region becase coherence factor is larger (b γ Hadronic b decays and the Unitarity triangle angle γ at 14

15 B c J/ψ3π π B c (b c the only meson containing heavy qarks of different flavor Test of QC factorisation Form factor of B c J/ψW π.1 pectral fragmentation of the W into nπ Measre ratio of branching fractions R π = B(B c J/ψ3π π B(B c J/ψπ - Bc b c W c c π n J/ ψ Predictions range from.9 to 1.1 A. V. Lchinsky, Phys. Rev. 86 (1 744 Hadronic b decays and the Unitarity triangle angle γ at 1

16 Reslts World s first measrement Fll data sample of 3 fb 1 : 1 fb 7 TeV and fb 8 TeV R. Aaij et al. ( Collab., arxiv: (14 J/ψ reconstrcted in di-mon channel pion distribtion generated according to varios QC factorisation models B c J/ψ3π π B c J/ψπ 1 Preliminary Preliminary Yield: 3 ± 8 events Yield: 71 ± 63 events 4.σ significance Hadronic b decays and the Unitarity triangle angle γ at 16

17 Reslts Efficiency ratio from MC ǫ(b c J/ψπ ǫ(b c J/ψ3π π Error from MC statistics only Ratio of brancing fractions = 13.8 ±.6 R π = N(B c J/ψ3π π N(B c J/ψπ ǫ(b c J/ψπ ǫ(b c J/ψ3π π = 1.74 ±.44 ±.4 ominant systematic ncertainty on π model Affects ǫ(b c J/ψ3π π Backgrond-sbtracted π distribtion 1 1 Preliminary Uncertainty 1: statistical, : systematic Consistent with theoretical predictions Consistent with analogos measrements with B and B. 3 Red: Model prediction Ble: -body phase space Reweight to data distribtion Hadronic b decays and the Unitarity triangle angle γ at 17

18 Λ b pπ No hadronic charmless 3-body decays yet observed in b baryons Interesting area to search for CP violating effects Analogos to large CP violating effects in hadronic charmless 3-body B mesons decays R. Aaij et al. ( Collab., PRL 111 ( ; PRL 11 ( W W Λb b g s - p B b d g s d - π d d Unknown heavy particle in the loop may case nepected CP violating effects Potential for New Physics Hadronic b decays and the Unitarity triangle angle γ at 18

19 Reslts data sample of 1 fb 7 TeV R. Aaij et al. ( Collab., arxiv:14.77 (14 Veto significant backgrond from Λ b Λ c [p ]h B π π sed as normalisation channel Candidates / ( 16.7 MeV/c ownstream Preliminary Candidates / ( 16.7 MeV/c Long Preliminary m( pπ [MeV/c ] m( pπ [MeV/c ] 8.6σ significance inclding systematic ncertainties, first observation Green crve shows concrrent search for Ξ b (sb baryon, not significant Hadronic b decays and the Unitarity triangle angle γ at 19

20 Reslts [GeV /c 4 ] m (p 3 1 Preliminary Backgrond sbtracted Λ b pπ alitz plot ignal detection efficiency weighted by alitz plot m 16 ( 18 [GeV /c 4 4 ] No clear peaking strctre ecept for low pπ mass Cold be from ecited ncleon states B(Λ b pπ = (1.6 ±.19 ±.9 ±.34 ±. 1 Uncertainties 1: statistical, : systematic, 3: f Λ b /f d, 4: B(B π π Measre integrated direct CP violation over the alitz plot A Raw CP = (N f N f /(N f N f Remove prodction and detection asymmetries with Λ b Λ c [ p]π control sample A CP (Λ b pπ =. ±.13 (stat ±.3 (syst Hadronic b decays and the Unitarity triangle angle γ at

21 mmary First model-dependent measrement of γ at sing B ± [ π π ] ± Consistent with tandard Model epectations imilar precision to model independent methods First A-like constraint of γ with B ± [ ± π ± ] ± Amplitde from CLEO γ consistent with other measrements First evidence of B c J/ψ3π π Branching fraction consistent with epectations from QC factorisation First observation of 3-body hadronic charmless b baryon decays No evidence for direct CP at this time Hadronic b decays and the Unitarity triangle angle γ at 1

22 Backp Hadronic b decays and the Unitarity triangle angle γ at

23 B ± [ π π ]π ± Long ownstream Candidates / ( 1 MeV/c (b Long Preliminary ± ± B π Cross-feed from ± ± B Partiallyreconstrcted backgrond m, inclding combinatoric backgrond m B [MeV/c ] Candidates / ( 1 MeV/c (b ownstream Preliminary ± ± B π Cross-feed from ± ± B Partiallyreconstrcted backgrond m, inclding combinatoric backgrond m B [MeV/c ] Table 1: Fitted signal and backgrond yields in the signal invariant mass region ( B mass after refit - world average < MeV/c for components contribting to the CP fit. Fit component B ± ±, long B ± ±, downstream ignal 17±17 4±7 Cross-feed backgrond (from B ± π ± 3.9±.7 76±1 Combinatoric backgrond Random h backgrond π backgrond.36±.8 6±7 ρ backgrond.±. 4±11 B s backgrond.9±. 4± Fit component B ± π ±, long B ± π ±, downstream ignal 96±6 96±8 Cross-feed backgrond (from B ± ± 7± 3±3 Combinatoric backgrond Random h backgrond π backgrond 6.6±.4.±.7 Hadronic b decays and the Unitarity triangle angle γ at 3

24 B ± [ π π ]π ± B π 1 3 [GeV /c m 4 ] 1 m [GeV /c 4 ] - m [GeV /c 4 ] Candidates / (.6 GeV /c B π 1 - m [GeV /c 4 ] m [GeV /c 4 ] Candidates / (.6 GeV /c 4 Candidates / (.18 GeV /c 4 - m [GeV /c Candidates / (.6 GeV /c 4 4 ] Preliminary [GeV /c 1 m - m 4 ] [GeV /c 4 ] m [GeV /c 4 ] Preliminary Candidates / (.6 GeV /c Candidates / (.18 GeV /c m [GeV /c 4 ] Hadronic b decays and the Unitarity triangle angle γ at 4

25 B ± [ π π ] ± escription δ ( 1 3 δy ( 1 3 δ ( 1 3 δy ( 1 3 (a -matri 1st soltion (b -matri nd soltion (c Remove slowly varying part in P-vector (d Generalised LA relativistic Breit-Wigner (e Gonaris-akrai relativistic Breit-Wigner (f m δm (g m δm (168 (h Γ δγ (i Γ δγ (j m δm (k m δm f (17 (l Γ δγ (m Γ δγ (n m δm (o (143 m δm (p Γ δγ (q Γ δγ (r r BW =. GeV (s r BW = 3. GeV (t Add (141 and ρ( Table : mmary of the model related systematic ncertainties for each alternative model. Hadronic b decays and the Unitarity triangle angle γ at

26 B ± [ π π ] ± orce of ncertainty δ ( 1 3 δy ( 1 3 δ ( 1 3 δy ( 1 3 Combinatoric yield estimate Inclsion of semileptonic backgrond Charged kaon detection asymmetry Amplitdes for backgronds Combinatoric Random h B s partially-reconstrcted r B ± π ± Efficiency over the phase space CP fit bias Total eperiment or fit related Total model related Table 3: mmary of absolte vales of systematic ncertainties Hadronic b decays and the Unitarity triangle angle γ at 6

27 B ± [ ± π ± ] ± candidates Entries / (1 MeV/c 3 1 B m, incl. combinatorics ignal Mis-I Partially reconstrcted [ π ] (a Entries / (1 MeV/c 3 1 B [ m, incl. combinatorics ignal π ] π (b Partially reconstrcted m([ π ] [MeV/c ] m([ π ] π [MeV/c ] Entries / (1 MeV/c 3 1 B [ m, incl. combinatorics ignal Mis-I π ] (c Partially reconstrcted Entries / (1 MeV/c 3 1 B [ m, incl. combinatorics ignal π ] π (d Partially reconstrcted m([ π ] [MeV/c ] m([ π ] π [MeV/c ] Hadronic b decays and the Unitarity triangle angle γ at 7

28 B ± [ ± π ± ] ± O candidates Entries / (1 MeV/c 3 1 B [ m, incl. combinatorics ignal Mis-I π ] (e Partially reconstrcted Entries / (1 MeV/c 3 1 B [ m, incl. combinatorics ignal π ] π (f Partially reconstrcted m([ π ] [MeV/c ] m([ π ] π [MeV/c ] Entries / (1 MeV/c 3 1 B m, incl. combinatorics ignal Mis-I Partially reconstrcted [ π ] (g Entries / (1 MeV/c 3 1 B m, incl. combinatorics ignal Partially reconstrcted [ π ] π (h m([ π ] [MeV/c ] m([ π ] π [MeV/c ] Hadronic b decays and the Unitarity triangle angle γ at 8

29 B ± [ ± π ± ] ± Table 1: ignal yields and their statistical ncertainties derived from the fit to the whole alitz plot region, and in the restricted region of phase space arond the (89 ± resonance. Whole alitz plot (89 ± region Mode ± π ± ± π ± 14±1 1841±47 97±1 136±38 O 71±1 167±37 6± 6 3±4 Table : Reslts for the observables measred in the whole alitz plot region, and in the restricted region of phase space arond the (89 ± resonance. The first ncertainty is statistical and the second is systematic. The corrections for prodction and detection asymmetries are applied, as is the efficiency correction defined in Eq. (. Observable Whole alitz plot (89 ± region R /O 1.8±.8±..7±.13 ±.6 R /π,.9±.9±.4.84±.11±.3 R /π, O.66±.9±..6±.13±. A,.4±.91±.18.6±.19±.9 A O,.33±.19±.4.336±.8±.6 A, π.±.4±.1.1±.8±.1.±.9±.17.4±.43±.17 A O, π Hadronic b decays and the Unitarity triangle angle γ at 9

30 B ± [ ± π ± ] ± Table 3: Absolte vales of systematic ncertainties, in nits of 1, for the fit to the whole alitz plot. Observable Eff. correction Fit PFs Prod. and det. PI Total asymms. R /O R /π, R /π, O A, A O, A, π...99 <.1.99 A O, π < Table 4: Absolte vales of systematic ncertainties, in nits of 1, for the fit in the restricted region. Observable Eff. correction Fit PFs Prod. and det. PI Total asymms. R /O R /π,.1... R /π, O A, A O, A, π <.1 1. A O, π < Hadronic b decays and the Unitarity triangle angle γ at 3

31 B c J/ψ3π π Table : Relative systematic ncertainties for the ratio R π. The total ncertainty is the qadratic sm of the individal components. orce Uncertainty [%] Fit model 6.6 ecay model m 3π π reweighting 7.7 ψ( mass veto 3.1 ata-simlation agreement Hadron interactions 4. Track qality selection 4.6 Trigger 1.1 Pion identification.7 election variables 1. B c lifetime.9 tability for varios data taking conditions. Acceptance.8 Total 13.9 Hadronic b decays and the Unitarity triangle angle γ at 31

32 Λ b Λ c [ p]π Candidates / ( 6 MeV/c ownstream Preliminary 6 7 m( pπ [MeV/c ] Candidates / ( 6 MeV/c Long Preliminary 6 7 m( pπ [MeV/c ] Table 1: Fitted yields and efficiency for each channel, separated by type. Yields are given with both statistical and systematic ncertainties, whereas for the efficiencies only the ncertainties de to the limited Monte Carlo sample sizes are given. The three rows for the B π π decay correspond to the different BT selections for charmless signal modes and the channels containing Λ c or s hadrons. Mode ownstream Long Yield Efficiency ( 1 4 Yield Efficiency ( 1 4 Λ b pπ 16.1±1.± 3.7.4±.1 9.9±14.6± 1..6±.6 Λ b p 11.±1.7± 1..34± ± 8.±.8.87±.7 Ξb pπ.3±1.7±.7.3±.1 6.4± 8.±..67±.7 Ξb p 1.± 8.8±. 6.1±.1 6.3±.6±.4.91±.7 Λ b Λ c ( pπ ±39.6± ± ±4.6± ±. Λ b Λ c ( p 7.±1.3± ± ± 7.1± ±.3 Λ b s p 6.3±.1±.6.69±. 6.± 3.7±..89±.3 B π π (ph 913.±4.±1..7± ±31.8± 7..86±.6 B π π (Λ c h ±6.7± ± ±33.3± ±.6 B π π (s p ±77.1± ± ±38.3± ±.7 Hadronic b decays and the Unitarity triangle angle γ at 3

33 Λ b pπ Control sample B π π with selection criteria of Λ b pπ Candidates / ( 16 MeV/c ownstream Preliminary m( π π [MeV/c ] m( π π [MeV/c ] Table : Relative systematic ncertainties on the branching fraction ratios (% with respect to B π π decays. The total is obtained from the sm in qadratre of all contribtions ecept that from knowledge of the fragmentation fractions. ownstream imlation PHP PI Fit model Fit bias Vetoes Total f Λ b /f d B(Λ b pπ < B(Λ b p B(Ξb pπ B(Ξb p B(Λ b Λ c ( pπ 6 <1 <1 8 7 B(Λ b Λ c ( p 4 < B(Λ b s ( p Long B(Λ b pπ <1 8 7 B(Λ b p B(Ξb pπ B(Ξb p B(Λ b Λ c ( pπ <1 <1 8 7 B(Λ b Λ c ( p < B(Λ b s ( p Candidates / ( 16 MeV/c Long Preliminary Hadronic b decays and the Unitarity triangle angle γ at 33