Beauty physics with B s and Λ b

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1 Beauty physics with B s and Λ b Rolf Oldeman INFN Roma 1 "La Sapienza" Selected topics Masses Lifetimes B s lifetime difference Charmless B s and Λ b decays B s oscillations Rare decays covered today by YoungJoon Kwon CP violation covered today by Emmanuel Olaiya Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

2 The B hadron family Not yet unambiguously observed: Ξ b - Ξ b 0 Ω b - bds bus bss Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

3 What's so special about spectator quarks? 1 2 b The spectator quarks makes or breaks a CP-Eigen state s c B d D s+ D - (CP mixed) vs B s D s+ D - s (CP even) c sizable lifetime difference in B s The spectator quark can exchange with the b vs B s oscillates >25 times faster than B d 3 The spectator quark can annihilate the b Br(B s µ + µ - ) Br(B d µ + µ - ) heavy B-hadrons provide unique window on B-physics Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

4 Producing heavy B hadrons Y(4S): B + / B 0 only B s at Y(5S): 10x smaller cross-section than Bd at Y(4S) Y(4S) e + e - above B s threshold: LEP 880k bb events/experiment SLC 85k bb events Y(5S) Fixed target E cm > 2m(B s ) Tried unsuccessfully at HERA-B σ(bb)/σ(total) 10-6 Hadron colliders: Operational: Tevatron, Chicago, 1.96 TeV pp σ bb /σ tot 10-3 Startup 2007: LHC, Geneve 14TeV pp σ bb /σ tot 10-2 Production ratio at high energy: B 0 : B - : B s : Λ b : B c 4 : 4 : 1 : 1 : 0.01 Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

5 Reconstructing B-decays Generally 3 types of B-decays accessible at hadron collider: Semi-leptonic B decays Pro: large branching ratios large yields Con: missing neutrino B decays to J/ψ Pro:muon provides easy trigger Con: small branching fractions Fully hadronic B decays Pro: 80% of branching fraction Con: requires silicon track trigger Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27, B + B + µ K + µ + D 0 π+ B + µ + ν µ K + π - D 0 K + π -

6 Tevatron detectors: CDF and DØ DØ: Larger muon coverage Better forward tracking Strong in J/ψ modes Strong in semi-leptonic modes CDF: Displaced track trigger PID: TOF and de/dx Better mass resolution Strong in fully hadronic modes Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

7 Forward is the future LHCb: startup 2007 BTeV: startup 2009 pp collisions at E cm =14TeV pp collisions at E cm =1.96TeV Forward region: High cross-sections High boost longer lifetimes Often both B's in acceptance Ring Imaging Cherenkov for π,k,p identification Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

8 Mass measurements Best mass measurements from fully reconstructed decays 100 events with 10MeV resolution give a 1 MeV mass measurement B c only observed in semileptonic decay large uncertainty on mass CDF Run I: m(b c )= GeV look forward to fully reconstructed B c J/ψ π + signal Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

9 New CDF m(b s ) and m(λ b ) results Dramatic improvements w.r.t to PDG2004: Little physics motivation to go below 1MeV level. Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

10 Beauty hadron lifetimes To first order: lifetime determined by fastest decaying quark τ(b + ) τ(b 0 ) τ(b s )τ(λ b )>> τ(b c ) Spectator effects can be calculated in Heavy Quark Expansion Dominated by (Λ QCD /m b ) 3 contributions Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

11 B s and Λ b lifetime measurements Best B +,B 0 lifetimes from Y(4S): 1% accuracy Best B s, Λ b results from semi-leptonic decays at CDF1, LEP : τ(b s )= ps τ(λ b )= ps τ(λ b )/τ(b d )= : shorter than predicted Needs correction for the missing neutrino. irreducible systematics from: decay model production model Fully reconstructed modes allow model-independent lifetime measurement Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

12 DØ/CDF B s and Λ b lifetime results Latest DØ and CDF fully reconstructed lifetimes approach competitive precision: CDF 220pb -1 : τ(b s J/ψφ)= ps DØ 115pb -1 : τ(b s J/ψφ)= ps CDF 65pb -1 : τ(λ b J/ψΛ)= ps Look forward this summer: B s, Λ b lifetime with more data semi-leptonic modes hadronic modes:b s D s π, Λ b Λ c π Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

13 B s lifetime difference B s has a large branching fraction to CP eigenstates Dominated by b ccs transition : B s D s( * )+ Ds ( * )- for B d : b ccd : Cabibbo suppressed 20 smaller SM prediction Γ s /Γ s = Γ L -Γ H = World average: Γ s /Γ s = ( < 0.29 at 95% CL) SLD,LEP,CDFI results + τ(b s )=τ(b d ) constraint Three ways to measure: Fit CP-mixed decay distribution to double exponential Only sensitive to ( Γ) 2 poor at low Γ Compare τ(b s CP even) to τ(b s CP mixed or CP odd) Angular analysis of B s J/ψ φ separates CP even and CP odd Semileptonic B s D s µν and hadronic B s D s π are CP mixed Indirect: measure Br ( B s D s( * )+ D s( * )- ) Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

14 B s J/ψ φ angular analysis Pseudoscalar Vector Vector decay 3 invariant angles: Θ K, Θ T, Φ T 3 (complex) amplitudes: A 0, A,A T Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

15 CDF angular analysis Using 180 B s J/ψ φ in 180pb -1 CDF finds: B s J/ψ φ is 80% CP-even expect τ(b s J/ψφ) < τ(b s D s µν) CP even short-lived CP odd long-lived Γ s is imminent Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

16 Charmless decays Rare b u transitions probe V ub and its phase γ In practice: spoiled by penguin transitions Compare B s, B d decays to disentangle penguin, V ub contributions 2-body decays challenging: B d K + π - overlaps B s K + K - CDF measures in 65pb -1 : Br(B s K + K - )/(B d K + π - ) = B s K + K - / B d π + π - SM OK! London, Matias hep-ph/ Statistical separation with 1.15σ de/dx and kinematics A CP,dir (Bd π + π - ) Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

17 New CDF search for Λ b pk,pπ Prediction: Mohanta, Giri, Khanna 2001 Br(Λ b pk) = ( )10-6 Br(Λ b pπ) = ( )10-6 Previous best limit from ALEPH: Br(Λ b pπ+pk) < Optimized search in the high-mass region of B ππ plot Compare to Br(B 0 K + π - )=(181) events in signal region 772 background events no signal observed Br(Λ b pπ+pk) < Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

18 First observation of B s φφ B sss penguin transition, The B s equivalent of B d φ K 0 S Predicted BR(B s φφ): Factorization: (0.4-25)10-6 Chen, Chen, Tseng 2003 QCD factorization: (18-37)10-6 Li, Lu, Yang 2003 Blind search: cuts optimized on signal MC and φ sidebands 12 observed, background BR(B s φφ)= (14 ± 6(stat.) ± 2(syst.) ± 5(BR's) ) 10-6 Wonderful channel with bright future for: Angular analyses Γ s measurement CP violation Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

19 B s oscillations B d oscillations are sensitive to V td Compromised by hadronic uncertainties Most cancel in B d /B s oscillation ratio: V td / V ts Double motivation: New physics may affect m s / m d m s measurement prerequisite for time-dependent CP violation measurements with B s Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

20 Current status of B s mixing Heavy Flavor Averaging group: Combined LEP,SLD,CDF1 Most analyses used partially reconstructed decays Poor sensitivity at high m s for m s > 15ps -1 σ(ct) above 67fs hurts! m s > 14.5 ps -1 more than 3 full oscillations per lifetime From CKM fit: m s < 30ps Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

21 Towards B s oscillations DØ has the largest yields in semileptonic modes: CDF has fully reconstructed hadronic decays The race is on! Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

22 Flavor tagging at hadron colliders For oscillations: compare flavor at production with flavor at decay Jet charge Soft lepton "opposite" side opposite Kaon b-hadron Vertexing side fragmentation Kaon Measure efficiency ε and dilution factor D εd 2 [%] Soft muon Soft electron Jet charge Same side (B + ) Opp. side kaon Same side kaon CDF 0.7 ± 0.1 in progress ± 0.5 in progress in progress Compare to B factories: ε D 2 30% DØ 1.6 ± 1.1 in progress 3.3 ± ± 2.0 Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27, B s D s - π + CDF Time-of Flight

23 Proof of principle: B d mixing 26k B 0 D* - µ + ν Opposite side muon tag 6k B 0 D - π +, J/ψ K* 0 same-side pion tag m d = ps -1 m d = ps -1 Both consistent with world average m d = Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

24 Conclusion Λ b and especially B s gives unique window on B physics CDF, DØ improved mass, lifetime using up to > 2 Run1 data B s J/ψ φ mostly CP even. Γ s measurements imminent New modes : Charmed hadronic: B s D s π, Λ b Λ c π Charmless hadronic: B s K + K -, B s φφ, new limit Λ b pk,pπ Ingredients for B s mixing getting ready The future for B s looks strange but beautiful Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

25 BACKUP Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

26 New results on B s µ + µ - Experimental B s µ + µ - B d µ + µ - CDFI DØ CDF Belle Babar Expected limit with 180pb -1 : Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

27 Mass scale calibration Critical: calibration of momentum scale to <1\times10-4 level Two components: B field calibration Material calibration use J/ψµ + µ - decays Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,

28 Tevatron performance RunII design: Record initial luminosity: on June 21, on June 22,2004 Delivered luminosity in 2004 already surpassed 2003 total High luminosity has a dark side: Less trigger bandwidth for B-physics Overlapping events degrade performance Rudolf Oldeman (INFN Roma 1 La Sapienza ) Physics in Collision 2004, Boston June 27,