Studies of b-hadron production and CKM matrix elements using semileptonic decays

Transcription

1 BEACH 218 Penihe, June 17-23, 218 Studies of b-hadron prodution and CKM matrix elements using semileptoni deays Olaf Steinkamp on behalf of the LHCb ollaboration Physik-Institut der Universität Zürih Winterthurerstrasse 19 CH-857 Zürih

2 LHCb [JINST 3(28)S85] Vertex loator p RICH detetors p B Traking system Muon system Calorimeters BEACH 218 Semileptoni LHCb (2) 2<η<5

3 LHCb [JINST 3(28)S85] Vertex loator RICH detetors Muon system Optimized for beauty and harm deays: p Low-pT trigger thresholds p B Exellent momentum and mass resolution Unique partile-identifiation apabilities Unique forward overage Traking system Calorimeters BEACH 218 Semileptoni LHCb (3) 2<η<5

4 Semileptoni Deays A deay aused by the weak fore in whih one lepton (and the orresponding neutrino) is produed in addition to one or more hadrons [ ℓ+ W Hb + νℓ b q q BEACH 218 Semileptoni LHCb (4)

5 Semileptoni Deays A deay aused by the weak fore in whih one lepton (and the orresponding neutrino) is produed in addition to one or more hadrons [ ℓ+ W Hb + νℓ b q q Ideal lab for, e.g., tests of Lepton Flavour Universality BEACH 218 Semileptoni LHCb (5)

6 Semileptoni Deays A deay aused by the weak fore in whih one lepton (and the orresponding neutrino) is produed in addition to one or more hadrons [ ℓ+ W Hb + νℓ b q q Ideal lab for, e.g., tests of Lepton Flavour Universality and measurements of CKM matrix elements BEACH 218 Semileptoni LHCb (6)

7 Semileptoni Deays Expet almost 1 million reonstruted semileptoni b deays from Run 1 + Run 2 All b flavours (B, B+, Bs, B+, Λb) Clean signatures for muoni modes low bakgrounds from non-semileptoni deays CP violating asymmetry assl in Bs - Bs mixing Tests of τ μ Flavour Universality [PRL 117(216)6183] [PRL 115(215)11183] BEACH 218 Semileptoni LHCb (7)

8 Semileptoni Deays Expet almost 1 million reonstruted semileptoni b deays from Run 1 + Run 2 All b flavours (B, B+, Bs, B+, Λb) Clean signatures for muoni modes low bakgrounds from non-semileptoni deays talk by Mark Smith yesterday morning CP violating asymmetry assl in Bs - Bs mixing Tests of τ μ Flavour Universality [PRL 117(216)6183] [PRL 115(215)11183] BEACH 218 Semileptoni LHCb (8)

9 Semileptoni Deays Preision measurements require good understanding of the hadroni part of the interation W+ ℓ+ νℓ b Hb q hadroni form fator q BEACH 218 Semileptoni LHCb (9)

10 Outline CKM matrix elements Vub Prodution of b hadrons Λb Λ+ form fator Fration of D, D*, D** in B D X μ νμ Flavour-speifi Bs lifetime Ω lifetime BEACH 218 Semileptoni LHCb (1)

11 Vub

12 Vub [Nature Phys 1(215)138] One side of the CKM Unitarity Triangle Can be determined from branhing frations of b u ℓ + νℓ transitions Long-standing disrepany between determinations from inlusive and exlusive deays LHCb measurement of νℓ 2 BF ( Λ b p μ ν μ ) V ub = R FF 2 V b BF (Λ b Λ μ ν μ ) b Vu()b ℓ u () Λb u u d d BEACH 218 Semileptoni LHCb (12)

13 Vub [Nature Phys 1(215)138] One side of the CKM Unitarity Triangle Can be determined from branhing frations of b u ℓ + νℓ transitions Long-standing disrepany between determinations from inlusive and exlusive deays LHCb measurement of 2 BF ( Λ b p μ ν μ ) V ub = R FF 2 V b BF (Λ b Λ μ ν μ ) Disriminating variable 2 2 m orr m p μ + p + p BEACH 218 Semileptoni LHCb (13)

14 Vub [Nature Phys 1(215)138] One side of the CKM Unitarity Triangle Can be determined from branhing frations of b u ℓ + νℓ transitions Long-standing disrepany between determinations from inlusive and exlusive deays LHCb measurement of 2 BF ( Λ b p μ ν μ ) V ub = R FF 2 V b BF (Λ b Λ μ ν μ ) Disriminating variable 2 2 m orr m p μ + p + p BEACH 218 Semileptoni LHCb (14)

15 Vub [Nature Phys 1(215)138] One side of the CKM Unitarity Triangle Can be determined from branhing frations of b u ℓ + νℓ transitions Long-standing disrepany between determinations from inlusive and exlusive deays LHCb measurement of 2 BF ( Λ b p μ ν μ ) V ub = R FF 2 V b BF (Λ b Λ μ ν μ ) Vb from exlusive measurements Form-fators from Lattie QCD BEACH 218 Semileptoni LHCb (15)

16 Vub [Nature Phys 1(215)138] One side of the CKM Unitarity Triangle Can be determined from branhing frations of b u ℓ + νℓ transitions Long-standing disrepany between determinations from inlusive and exlusive deays LHCb measurement of 2 BF ( Λ b p μ ν μ ) V ub = R FF 2 V b BF (Λ b Λ μ ν μ ) Vb from exlusive measurements Form-fators from Lattie QCD BEACH 218 Semileptoni LHCb (16)

17 Λ Λ form fator b +

18 Λb Λ+ form fator Chek preise preditions from Lattie QCD Showase the potential for form-fator measurements in LHCb Detmold, Lehner, Meinel [PRD92(215)3453] Heavy Quark limit form fators redue to one Isgur-Wise funtion Perform a Taylor expansion and fit the first two terms ξ B (w ) = 1 ρ 2 (w 1) σ 2 (w 1)2 + with w m 2Λ + m 2Λ q 2 b + 2 mλ mλ b + BEACH 218 Semileptoni LHCb (18)

19 Λb Λ+ form fator [PRD96(217)1125] Analysis based on Run-1 data sample: 3 fb-1 at 7 and 8 TeV Clean event sample of 2.7 million Λ+ μ andidates with Λ+ p K π+ Bakground from prompt Λ+ found to be negligible Bakgrounds from exited Λ+ resonanes estimated from Λ b Λ π + π μ νμ Λ(2625)+ Λ(2595)+ Λ(2765)+ Λ(288)+ BEACH 218 Semileptoni LHCb (19)

20 Λb Λ+ form fator [PRD96(217)1125] Two-fold ambiguity in determination of w due to missing neutrino: Use solution with smaller value of Λb momentum (orret in 5-6 % of ases) Determine resolution and bias on w from simulation Unfold measured distribution using Single Value Deomposition BEACH 218 Semileptoni LHCb (2) Hoeker and Kartvelishvili [NIM A372(1996)469]

21 Λb Λ+ form fator [PRD96(217)1125] Extrat ρ2 and σ2/2 from χ2 fits to d N orr /d w K (w ) = onst ξ B (w ) ( K(w): kinematial fator ) Results ompatible with expetation from theory 2 ρ = 1.63 ±.7 (stat ) ±.8 (syst ) [PLB 629(25)27] [PRD 57(1998)6948] [PRD 73(26)942] BEACH 218 Semileptoni LHCb (21)

22 f (D,D*,D** ) in B D X μ νμ

23 f (D,D*,D**) in B D X μ νμ [LHCb-PAPER ] (in preparation) Frations of D, D*, D** produed in semileptoni b deays not yet well known Relevant, sine higher resonanes onstitute bakground for exlusive deays B D ℓ ν and B D* ℓ ν, e.g. in measurements of R(D) or R(D*) Use B andidates from Bs2* B K+ Reonstrut B momentum vetor from known Bs2*, B and K+ masses, B prodution and deay verties, K momentum and flight diretion preliminary BEACH 218 Semileptoni LHCb (23)

24 f (D,D*,D**) in B D X μ νμ [LHCb-PAPER ] (in preparation) Frations of D, D*, D** produed in semileptoni b deays not yet well known Relevant, sine higher resonanes onstitute bakground for exlusive deays B D ℓ ν and B D* ℓ ν, e.g. in measurements of R(D) or R(D*) Use B andidates from Bs2* B K+ Reonstrut B momentum vetor from known Bs2*, B and K+ masses, B prodution and deay verties, K momentum and flight diretion Reonstrut D K π+ and alulate preliminary 2 m miss p B2 p D2 μ to distinguish between D, D*,D** BEACH 218 Semileptoni LHCb (24)

25 f (D,D*,D**) in B D X μ νμ [LHCb-PAPER ] (in preparation) Frations of D, D*, D** produed in semileptoni b deays not yet well known Relevant, sine higher resonanes onstitute bakground for exlusive deays B D ℓ ν and B D* ℓ ν, e.g. in measurements of R(D) or R(D*) Use B andidates from Bs2* B K+ Reonstrut B momentum vetor from known Bs2*, B and K+ masses, B prodution and deay verties, K momentum and flight diretion preliminary Reonstrut D K π+ and alulate 2 m miss p B2 p D2 μ to distinguish between D, D*,D** BEACH 218 Semileptoni LHCb (25)

26 f (D,D*,D**) in B D X μ νμ [LHCb-PAPER ] (in preparation) Signal: B D X μ νμ with B from Bs2* B K+ preliminary Dominant bakground from deays of B and B not from Bs2* Modeled using same-sign Kaon andidates Bakground from B D X D and B D X τ ντ modeled using simulation preliminary Bakground from Bs and Λb deays and mis-reonstruted deays modeled using data-driven methods BEACH 218 Semileptoni LHCb (26)

27 f (D,D*,D**) in B D X μ νμ [LHCb-PAPER ] (in preparation) Signal: B D X μ νμ with B from Bs2* B K+ preliminary Dominant bakground from deays of B and B not from Bs2* Modeled using same-sign Kaon NEW: shown here andidates for the first time Bakground from B D X D and B D X τ ντ modeled using simulation preliminary Bakground from Bs and Λb deays and mis-reonstruted deays modeled using data-driven methods BEACH 218 Semileptoni LHCb (27)

28 f (D,D*,D**) in B D X μ νμ [LHCb-PAPER ] (in preparation) preliminary f (D ) =.27 ±.6 ry a n i m i rel f (D ) =.14 ±.7 p f (D ) 1 f (D ) f (D ) BEACH 218 Semileptoni LHCb (28)

29 Flavour-speifi B lifetime s

30 Flavour-speifi Bs lifetime [PRL119(217)1181] D Measure flavour-speifi Bs lifetime in ( ) Bs Ds Ds + μ νμ Sensitive to deay-width differene between heavy and light eigenstates in the Bs Bs system Large yields, but systematis from missing neutrino Perform measurement relative to B D ( ) + μ νμ reonstruting Ds(*) and D(*) in deay to K+ K π D (s ) π + veto BEACH 218 Semileptoni LHCb (3)

31 Flavour-speifi Bs lifetime [PRL119(217)1181] Analysis based on Run-1 data sample: 3 fb-1 at 7 and 8 TeV Event samples of 468 k Ds μ+ and 141 k D μ+ andidates 1 Δ Γ B =.115 ±.53 (stat) ±.41 (syst) ps fs τ B = ±.13 (stat) ±.1 (syst) ±.1 ( τ B ) ps s BEACH 218 Semileptoni LHCb (31)

32 Flavour-speifi Bs lifetime [PRL119(217)1181] By-produt: measurement of Ds lifetime 1 Δ Γ D = ±.117 (stat) ±.65 (syst) ps τ D =.546 ±.3 ( stat) ±.17 (syst) ±.17 ( τ D ) ps s BEACH 218 Semileptoni LHCb (32)

33 Ω lifetime

34 Ω lifetime [LHCb-PAPER ] (in preparation) Ω lifetime so far known only to 17 % preision More preise measurement interesting, e.g. to test hierarhy expeted from Pauli interferene: τξ > τλ > τξ > τω e.g. Browder, Honsheid, Pedrini [arxiv:hep-ph/966354] Measurement uses sample of Ω b Ω μ ν μ X with Ω p K K π To minimize systematis, measure lifetime relative to D+ lifetime from B D + μ ν μ X with D+ K π π BEACH 218 Semileptoni LHCb (34)

35 Ω lifetime [LHCb-PAPER ] (in preparation) Ω lifetime so far known only to 17 % preision More preise measurement interesting, e.g. to test hierarhy expeted from Pauli interferene: τξ > τλ > τξ > τω e.g. Browder, Honsheid, Pedrini [arxiv:hep-ph/966354] NEW: first shown at LHCP two weeks ago Measurement uses sample of Ω b Ω μ ν μ X with Ω p K K π To minimize systematis, measure lifetime relative to D+ lifetime from B D + μ ν μ X with D+ K π π BEACH 218 Semileptoni LHCb (35)

36 Ω lifetime [LHCb-PAPER ] (in preparation) Ω lifetime so far known only to 17 % preision More preise measurement interesting, e.g. to test hierarhy expeted from Pauli interferene: τξ > τλ > τξ > τω e.g. Browder, Honsheid, Pedrini [arxiv:hep-ph/966354] From analysis of Run-1 data sample: 3 fb-1 at 7 and 8 TeV τω τ D =.258 ±.23 (stat ) ±.1 (syst) + τ Ω = 268 ± 24 (stat) ± 1 (syst ) ± 2 ( τ D ) fs + ry a n i m i prel BEACH 218 Semileptoni LHCb (36)

37 Ω lifetime [LHCb-PAPER ] (in preparation) Ω lifetime so far known only to 17 % preision More preise measurement interesting, e.g. to test hierarhy expeted from Pauli interferene: τξ > τλ > τξ > τω e.g. Browder, Honsheid, Pedrini [arxiv:hep-ph/966354] Four times larger than urrent PDG average BEACH 218 Semileptoni LHCb (37)

38 Ω lifetime [LHCb-PAPER ] (in preparation) Ω lifetime so far known only to 17 % preision More preise measurement interesting, e.g. to test hierarhy expeted from Pauli interferene: τξ > τλ > τξ > τω e.g. Browder, Honsheid, Pedrini [arxiv:hep-ph/966354] Four times larger than urrent PDG average τξ > τω > τ Λ > τξ Learn something about the dynamis of the ss quark pair? BEACH 218 Semileptoni LHCb (38)

39 Summary No news from LHCb (yet) on Vub Analyses in progress, see bakup slides New measurements on Λb Λ+ form fator Fration of D, D*, D** in B D X μ νμ Preliminary Presented here for the first time Flavour-speifi Bs lifetime Ω lifetime BEACH 218 Semileptoni LHCb (39) Preliminary

40 Summary No news from LHCb (yet) on Vub Analyses in progress, see bakup slides New measurements on Λb Λ+ form fator [PRD96(217)1125] Fration of D, D*, D** in B D X μ νμ [LHCb-PAPER ] (in preparation) Flavour-speifi Bs lifetime [PRL119(217)1181] Ω lifetime [LHCb-PAPER ] (in preparation) ( Ds± prodution asymmetry ) [arxiv: ] BEACH 218 Semileptoni LHCb (4)

41 Thank You

42 Ds± prodution asymmetry [arxiv: ] By-produt of the assl analysis [PRL 117(216)6183] Reonstrut prompt Ds± ϕ π± with ϕ K+ K Measure raw asymmetry + Araw N (D s ) N (D s ) N (D +s )+N (D s ) in bins of pt and rapidity Corret for Ds-from-B bakground and detetion asymmetries AP = 1 1 f bkg ( Araw AD f bkg AP (B) ) Bakground fration and asymmetries from simulation and literature Detetion asymmetries from data-driven methods BEACH 218 Semileptoni LHCb (42)

43 Ds± prodution asymmetry [arxiv: ] Analysis based on Run-1 data sample: 3 fb-1 at 7 and 8 TeV ( ) million D andidates with 97 % purity ± s 8.5 < pt < 25 GeV/ 3.5 < y < 4.5 Mag down BEACH 218 Semileptoni LHCb (43)

44 Ds± prodution asymmetry [arxiv: ] Analysis based on Run-1 data sample: 3 fb-1 at 7 and 8 TeV ( ) million Ds± andidates with 97 % purity Compatible results for the two field orientations of spetrometer magnet BEACH 218 Semileptoni LHCb (44)

45 Ds± prodution asymmetry [arxiv: ] Analysis based on Run-1 data sample: 3 fb-1 at 7 and 8 TeV ( ) million Ds± andidates with 97 % purity Compatible results for the two field orientations of spetrometer magnet Find no signifiant dependene on rapidity or pt In ontrast to expetation from Pythia BEACH 218 Semileptoni LHCb (45)

46 Ds± prodution asymmetry Learn something about the s-quark ontent of the proton? BEACH 218 Semileptoni LHCb (46)

47 Vub BEACH 218 Semileptoni LHCb (47)

48 Vub νℓ Work ongoing towards a measurement of 2 s s + BF (B K μ ν μ ) V ub = R FF 2 + BF (B D s μ ν μ ) V b b Vu()b s ℓ u () s preliminary BEACH 218 Semileptoni LHCb (48)

49 Vub Working on a searh for B μ μ μ νμ Branhing fration sensitive to Vub Extra μ+ μ pair breaks heliity suppression provides deay vertex Deay not yet observed, expet BF(B μ μ μ ν μ ) 1 [EPJ Web Conf 158(217)35] Analysis uses full Run-1 data set fb-1 from Run-2 Expet to be able to exlude signal down to few 1-8 BEACH 218 Semileptoni LHCb (49)

50 Vub BEACH 218 Semileptoni LHCb (5) [Nature Phys 1(215)138]

51 Λb Λ+ form fator BEACH 218 Semileptoni LHCb (51) [PRD96(217)1125]

52 f (D,D*,D**) in B D X μ νμ [LHCb-PAPER ] (in preparation) ary n i m i l p re BEACH 218 Semileptoni LHCb (52)

53 Flavour-speifi Bs lifetime [PRL119(217)1181] BEACH 218 Semileptoni LHCb (53)

54 Ω lifetime [LHCb-PAPER ] (in preparation) ry a n i m i prel BEACH 218 Semileptoni LHCb (54)