LHCb overview. Polyakov Ivan Syracuse University. (on behalf of the LHCb collaboration)

Transcription

1 LHCb overview Polyakov Ivan Syracuse University (on behalf of the LHCb collaboration) Miami 2016, Florida 14 December 2016

2 LHCb Physics program CKM and CPV with b and c hadrons > 340 papers! > 50 in only 2016 link to LHCb public results Rare decays of b and c hadrons Heavy flavor production Spectroscopy in pp collisions and B decays EW, QCD + Exotica in forward region 2

3 LHCb detector High cross-section of heavy-quark production Excellent decay time resolution Excellent particle identification Excellent momentum resolution Cherenkov detectors ε(µ µ) ~ 97% at 1-3% π µ mis-identification bb-pair production σip ~ 20 μm for high pt tracks p IJMPA 30 (2015) Data collected in Run1: 1 fb-1 at 7 TeV 2 fb-1 at 8 TeV in Run2: 2 fb-1 at 13 TeV Muon system ε(k K) ~ 95% at 5% π K mis-identification VELO JINST 3 (2008) S08005 LHCb acceptance p B CMS/ATLAS acceptance Interaction point Tracking system Δp/p = 0.5% at 20 GeV/c to 0.8% at 100 GeV/c Calorimeters ECAL: σe/e ~ 1% 10%/ E [GeV] 3

4 Outlook LHCb detector & program (>50 new results in 2016) Measurements of CKM and CPV Rare decays Heavy quark production and spectroscopy. Exotic hadron states Electro-weak sector see talk by Elena Graverini Semi-tauonic physics Heavy flavor production at 13 TeV Prospects 4

5 CKM 5

6 CKM matrix and Unitarity Triangle The only SM source of CPV in quark sector Complex CKM matrix unitarity requirement Can't explain baryonic asymmetry in the universe should be additional mechanism beyond SM Measure the CKM parameters to find inconsistencies in UT clue to NP 6

7 Combination for in 2016 arxiv: Previous combination in 2014 Measurements performed (tree process dominated decays) NEW Updated to 3 fb-1 PLB 760 (2016) 117 New PRD 91 (2015) JHEP 10 (2014) 097 PLB 733 (2014) 36 New PRD 92 (2015) PRD 90 (2014) New New PRD 93 (2016) JHEP 08 (2016) 137 JHEP 11 (2014) 060 7

8 Combination for in 2016 arxiv: B DK and B Dπ measurements are well consistent Most sensitivity from B+ DK+ Full combination: DK measurements Twice more precise than B-factory combinations Agrees with and surpasses previous combination of DK measurements Plus recent result with Bs Ds-/+K+/- N NEEW W -1 based on 3 fb LHCb-CONF consistent with combination above within ~2σ 8

9 ACP in B K K /B π π 0 s + - Rich set of processes participating - B mixing - tree and penguin decay diagrams NEW Time-dependent CPV observables sensitive to γ and 2β(s) Precision improved by factor 2 most precise measurement of Sππ first measurement of AKK first observation of CPV in Bs K+K- with 5.3σ 36k-45k signal events LHCb-CONF in preparation 9

10 ACP in D0 K+K-/π+π Time dependence of CP asymmetry in case of slow D0-D0 oscillations if adir is negligible then aind=aг Time integrated analysis Mainly sensitive to adir as aind should cancel out in the difference: ΔACP = ACP(KK)-ACP(ππ) ~ Δadir Use D*+ D0π+slow and B Dlν tags SL: Prompt: JHEP 07 (2014) 041 PRL 116 (2016) Combination (Run1): N NEEW W arxiv:

11 ACP in D0 K+K-/π+π Time dependent analysis more sensitive to aind Use D*+ D0π+slow tag Perform analysis with two strategies: - binned in time - unbinned Assuming universality of AГ=aind get following AГ equal to - binned: - unbinned: LHCb-CONF LHCb-CONF Fluctuations due to background from B No evidence of CPV 11

12 Mixing and CPV in D0 Kπ NEW Explore time-dependent ratio R(t)=Г(D0 K+π-)/Г(D0 K-π+) No evidence for CPV in mixing has been report yet SM expectation: <10-3 Previously studied via D*+ D0π+ tag PRL 111 (2013) Now use B D*lν, D*+ D0π+ double tag + better purity + unbiased decay time trigger - 40 times fewer statistics arxiv: Improved results, no CPV seen 12

13 CPV in Λb pπ π π NEW CPV has never been observed in baryons before Investigate the following observables for local CPV effects as function of angle between pπ and ππ decay planes: from b-quark decay An evidence for CPV at 3.3σ (incl syst) is found arxiv: First evidence of CPV in baryons Asymmetry, % Nsig=6646±105 13

14 Rare decays 14

15 B0 K*0μ+μ FCNC process (similar diagram as for Bs μ+μ-) Angular variables less affected by QCD uncertainties more sensitive to NP JHEP 02 (2016) 104 Nsig=2398±57 15

16 B0 K*0μ+μ- Local deviation of >3σ in P'5 in 2011 analysis confirmed Vector coupling ΔRe(C9)=-1.04±0.25 while SM value: σ tension Sign of either hadronic effects or non-sm particles 3.7σ JHEP 02 (2016)

17 Photon polarization in Bs ϕγ arxiv: In SM right photon polarization in b sγ is suppressed as ms/mb Determine A from time-dependent rate: Δ Nsig=4072±112 in ratio with B0 K*0γ Measured for the first time: compatible with SM within 2σ Can be improved with tagging 17

18 Observation of B0 K+K NEW Can proceed only through annihilation/exchange diagrams test of QCD calculations Nsig=201±36 B0 K+K- observed for the first time with significance of 5.8σ The rarest decay into hadronic final state ever observed Agrees with pqcd estimation of ~10-7 within uncertainties arxiv: Xiao, Wang, Fan. PRD 85 (2012)

19 Searches for other rare decays First search for B(s)0 τ+τ- with τ- π+π-π- ντ SM: ~ in some NP scenarios (not forbidden by B(s)0 μ+μ-) BF could be enhanced up to percent level LHCb-CONF arxiv:1611:07704 New limits on B 4μ. In MSSM enhanced by sgoldstinos SP: B S( μ+μ-)p( μ+μ-) 0 (s) New limit for KS0 μ+μsm: previous limit: <11(9) at 95(90)% CL LHCb-CONF Evidence for Σ+ pμ+μ-, search for X0 μ+μ- with at 214 MeV LHCb-CONF Search for CPV in strong sector in η(') π+π decays through D(s)+ π+π-π+: arxiv:

20 Exotic hadron states 20

21 Λ J/ψpK 0 b In 2015 two pentaquarks in Λb0 J/ψpK decays were observed by 6D amplitude analysis. Only certain resonances in pk considered PRL 115 (2015) Pc+(4450) Pc+(4380) Model independent analysis of the same decay with unphysical spins allowed (up to 31/2) No restrictions on number/masses/widths of Λ* pk resonances, only spins are restricted Then, try to describe J/ψp mass represent cosθλ* as sum of Legendre polynomials with l<lmax with restrictions on spin of Λ* Reject only Λ* hypothesis with >9 standard deviations N=27469 fbkg=5.4% PRL 117 (2016)

22 Λb J/ψpπ 0 Explore Cabibbo suppressed Λb0 J/ψpπ decay Similar 6D amplitude analysis approach - consider 15 well-established N* resonances - probe for both Pc+ J/ψp and Zc(4200)- J/ψπ- observed by Belle PRD 88 (2013) PRL 117 (2016) Nsig=1885±50 fbkg~17% 22

23 Λb J/ψpπ 0 PRL 117 (2016) Evidence for exotic contribution with 3.1σ significance (Pc(4380)+, Pc(4450)+ and Zc(4200)- together) Individual contributions are not significant Pc+ production rates consistent with that from Λb Pc+K decay considering Cabibbo suppression M(pπ)>1.8 GeV M(pπ)>1.8 GeV 23

24 B+ J/ψϕK+ PRL 102 (2009) Observation of two structures in J/ψϕ system at 4140 and 4274 by CDF Later confirmations (D0, CMS, BaBar) and non-confirmations (Belle, LHCb, BaBar) PLB 734 (2014) 261 PRD 89 (2014) Moriond QCD 2014 LeptonPhoton 2009 PRL 104 (2010) arxiv: PRD 85 (2012) Contradictions in masses and the whole J/ψϕ mass spectra CDF Belle LHCb arxiv: CMS D0 BaBar The different efficiencies in phasespace can produce different interference patterns an amplitude analysis is essential! 24

25 B+ J/ψϕK+ Perform 6D amplitude analysis The highest statistics so far Allow floating masses and widths for K* ϕk excitations arxiv: arxiv: Nsig=4289±151 fbkg~23% established unconfirmed 25

26 B+ J/ψϕK+ arxiv: arxiv: Data can't be described with K* contributions only 4(!) resonances in J/ψϕ are required, with >5σ significance each 12K*+NR (p~10-7) arxiv: arxiv: substantially larger than in CDF/CMS/D0 1++: X(4140): M = ± MeV, Г = 83± MeV X(4274): M = ± MeV, Г = 56± MeV 0++: X(4500): M = 4506± MeV, Г = 92± MeV X(4700): M = 4704± MeV, Г = 120± MeV 7K*+NR+4X (p=0.22) For X(4140) a DsDs* cusp is preferred by 1.6σ. No success in describing other structures as cusps. Significant input to K* spectroscopy 26

27 Heavy Quark Spectroscopy N NEEW W Dalitz analysis of D+ K+K-K+ Dalitz analysis of B- D+π-π-, first observation of D*3(2760), D*2(3000) Study of DsJ(*)+ D*+/0K0/+ Observation of ηc(2s) pp and upper limit on X(3872) pp Bc χc0π+ First observation of Bc D0K+ Properties of Ξ*b Lifetime and mass of Ωb Most precise measurement of Λb mass Observation of Λb Λϕ Λb/Ξb Λhh' Non-observation of X(5568)+ Bsπ+ claimed by D0 LHCb-CONF PRD 94 (2016) JHEP 02 (2016) 133 arxiv: PRD 94 (2016) arxiv: JHEP 05 (2016) 161 PRD 93 (2016) JHEP 05 (2016) 132 PRL 116 (2016) JHEP 05 (2016) 081 PRL 117 (2016)

28 b&c production at 13 TeV 28

29 b-hadron x-sections at 13 TeV JHEP 10 (2015) 172 In 2015 measurement of J/ψ production from b-decays revealed higher rates for low rapidities than expected A dedicated analysis of B+,B0,Bs and Λb production has been performed using semileptonic decays with muon The trends at low η confirmed - future measurements with exclusive final states will provide further input for theory arxiv: N NEEW W c&b-hadron x-sections at 13 TeV are ~2 larger with respect to 7/8 TeV 2fb-1 data of 2015/2016 has ~30% more c&b-hadrons than 3fb-1 of Run1 29

30 Special mechanisms for charmonium production Central exclusive production of J/ψ and ψ(2s) 13k J/ψ and 382 ψ(2s) candidates LHCb-CONF Double J/ψ production in fiducial range pt(j/ψ)<10 GeV, 2<y(J/ψ)<5 N=1048±51 N NEEW W Comparable with theory predictions for SPS Preliminary Noticeable fraction of DPS contribution LHCb-PAPER in preparation 30

31 Prospects LHCb operation plan LHCb Upgrade Today L = 4x1032 L = 3-4x fb-1 L = 10-20x1032 8(=3+5) fb-1 >50 fb-1 Major improvements in key measurements: LHCb-TDR-12 31

32 LHCb Upgrade Operating at L=2x1033 cm-2s-1 requires some new detectors and 40MHz read-out clock new electronics VELO: new pixel vertex detector UT VELO Tracking system: new Scintillating Fibre tracker and silicon Upstream Tracker RICH1 SciFi RICH2 + Trigger PID: Hybrid photodetectors to be replaced by multi-anode PMTs Trigger: completely software-based trigger 32

33 Summary LHCb became the leading experiment to explore CKM matrix Rare decays Exotic hadrons (+ natural HF spectroscopy and production) EW & QCD and Exotica at forward region with such wide physics program LHCb is more like a general purpose experiment in forward region Data sample collected at 13 TeV is being analyzed And we are looking forward for larger statistics of Run2 (and Run3) for even more important results and discoveries 33

34 Backup 34

35 X(5568)± Bsπ± Observation with significance >5σ claimed by D0 M=5567.8± MeV Γ=21.9± MeV f(bs from X+)=8.6% PRL 117 (2016) NBs=5.5k LHCb has 20 times larger and much cleaner sample (J/ψϕ and Dsπ modes used) PRL 117 (2016) NBs=44k S/B=50 NBs=62k S/B=10 35

36 X(5568)± Bsπ± No evidence for any X± Bsπ± Set upper limit on fraction of Bs from X± as function of M and Γ: PRL 117 (2016) for M and Γ fixed to D0's ρlhcb<2.1 at 90% C.L. while ρd0=(8.6±1.9±1.4)% 36

37 Mixing in B0 D+D Time dependent analysis of decay to CP-even final state allows to probe sin2β B flavor ~sin(2β+δφ) Nonzero Δφ and C correspond to loop contributions, which BaBar and Belle measurements show to be the case arxiv: Though LHCb results consistent with SM arxiv:

38 CPV in BS mixing 0 Time-integrated asymmetry: Small in SM: Artuso, Borissov, Lenz. arxiv: p~0.5% Interest triggered by D0 observing large like-sign muon asymmetry PRD 89 (2014) Latest measurement with Bs DsμνX, Ds KKπ decays PRL 117 (2016)

39 ϕs in B ψ(2s)ϕ 0 s Several measurements at Tevatron and LHC World average ϕs=-30±33 mrad compatible with SM Latest measurement by LHCb using Bs ψ(2s)ϕ for the first time: ϕs=-230±290 mrad arxiv:

40 B0 K+π-μ+μ-, S-wave fraction arxiv: Determine S-wave in B0 K+π-μ+μunder B0 K*0μ+μ- and its BF Disentangle S- and P-waves as SM predictions are for P-wave only FS(q2) dependence is in agreement with that expected from FL(q2) (in 796<mKπ<996 MeV range) 40

41 B0 K+π-μ+μ-, K*0,2(1430)0 region arxiv: Analysis of differential BF and of angular moments in bins of q2 41

42 Evidence for Σ+ pμ+μ Another decay via FCNC process SM: 1.6x10-8<B < 9x10-8 Evidence by HyperCP PRL 94 (2005) all three candidates had almost the same μμ mass: 214.3±0.5 MeV Based on Run1 data the signal is observed with 4σ significance. Due to lack of events in independently triggered sample only an UL is defined: LHCb-CONF

43 Search for CP violating η(') ππ arxiv: CP in weak is not enough to explain baryon asymmetry in the universe might be in strong sector Current limits: KLOE, PLB606 (2005) 276 BESIII, PRD 84 (2011) Run1+2: ND=25M Run1+2: ND=24M Search in D(s)+ π+π-π+ decays, normalize to known B(D(s)+ η(')π+) No signal, the limits measured: 43

44 Flavor tagging at LHCb εd2, % Channel Bs0 ϕϕ Bs0 Ds+Ds Improvement Reference +64% [PRD 90 (2014) ] 5.33 [PRL 113 (2014) ] Bs0 Ds+K Bs0 J/ψK+K % [PRL 114 (2015) ] Bs0 J/ψπ+π % [PLB 736 (2014) 186] B0 J/ψKs % [PRL 115 (2015) ] [JHEP 11 (2014) 060] Significant improvements in performance in the last 3 years 44

45 Snapshot of EW&Exotica at LHCb W eν production at 8 TeV Z μμ production at 13 TeV JHEP 10 (2016) 030 JHEP 09 (2016) 136 W/Z + jets at 8 TeV JHEP 05 (2016) 131 Search for H cc/bb associated with W/Z LHCb-CONF tt, W+cc/bb at 8 TeV arxiv: Search for H decays into massive long-lived particles arxiv:

46 Prospects 46