LHCb prospects in flavour physics and CP violation Stephan Eisenhardt, University of Edinburgh On behalf of the LHCb experiment Introduction – LHCb Physics Programme fs: BS  J/Y f g: B±  DK± rare decays: BS  mm, B0K*0mm Conclusions EPS 2007, Manchester, 20.07.2007

LHCb Physics Programme  g ~Vub* ~Vtd ~Vts g b a ~Vub* ~Vtd ~Vcb g-2 g and g Rare decays - very sensitive to NP Radiative penguin e.g. Bd  K* g, Bs  f g Electroweak penguin e.g. Bd  K*0 m+m- Gluonic penguin e.g. Bs  ff, Bd  fKs Rare loop diagram e.g. Bs m+m- B production, Bc, b-baryon physics Charm decays Tau Lepton flavour violation EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

_ fS: BsJ/Yf bccs  fS = fSSM+fSNP BS mixing phase is very small in SM: fS = -0.037 ± 0.002 rad (BsJ/Yf : fS=-2c) not yet measured could be much larger if New Physics adds to BS0-BS0 transitions BS0f BS0BS0f +NP? measure time-dependent asymmetry in decay rates: need flavour tagging need very good proper time resolution to resolve BS0-BS0 oscillations need angular analysis to separate CP-even and CP-odd contributions  fS = fSSM+fSNP EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

fS: BsJ/Yf wtag, s(t) fS = 0.2 = 5SM full LHCb MC Flavour tagging: Tagging efficiency: etag – probability that tagging procedure gives an answer Wrong tag fraction: wtag – probability for the answer to be wrong Dilution of the observed asymmetry: D = 1 – 2wtag Effective tagging efficiency: eeff = etagD2 = 7.08 ± 0.23 % fS = 0.2 = 5SM + wrong tag fraction + proper-time resolution + acceptance BS0 tag full LHCb MC Proper time resolution: dependent on reconstruction errors of final states LHCb: most channels have proper-time resolution ~ 40fs BsJ/Yf: s(t) = 36.0 fs EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

fS: BsJ/Yf angular analysis BSJ/Y(l+l-)f(K+K-): golden channel theoretically clean experimentally easy: mm trigger and 4 charged tracks LHCb: yield in 2 fb-1: 131k, B/S=0.12 angular analysis: disentangle mixture of CP-even (hf=-1, A0, A||) and CP odd (hf=+1, A) 1-angle analysis: qtr wrong-tag fraction: wtag from control sample BSDSp needs external DmS gives: fS, DGS 3-angle analysis: qtr, ftr, qf better separation power indication: wtag and DmS can be measured as well (to lower accuracy wrt. external measurements) total CP even CP odd flat background EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

fS: BsJ/Yf sensitivity BSJ/Y(l+l-)f(K+K-): for 1-angle analysis: sensitivity for s(fS) = 0.023 rad, s(DGS/GS) = 0.0092 2 fb-1 = “1 yr of LHCb”: Add other CP-even final states: combined relative weight: only 13% total sensitivity for 2 fb-1: s(fS) = 0.021 rad Constraining New Physics in BS mixing from fS measurement: Parameterise NP with mixing amplitude ASNP/ASSM and phase fSNP ASNP/ASSM fSNP hep-ph/200604112 >90% CL >32% CL >5% CL CDF: DmS 04/2006 included ASNP/ASSM fSNP After LHCb measurement of fS with s(fS)=±0.1 (~0.2 fb-1) EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

g: B±D0K± ADS method Charged B decays to D0 or D0 and K: D0 and D0 can both decay into K-p+ (and K+p-): Four decay rates: two favoured with small interferences (opposite-sign p) two suppressed with large interferences (like-sign p) Counting experiment: no flavour tagging, no proper time analysis Only through D0 mixing sensitive to NP 3 relative decay rates vs. 5 parameters: rB, rD, dB, dD, g rD well measured; but dD poorly constraint by CLEO-c (Dcos dD ~ 20%) Atwood, Dunietz and Soni, Phys. Rev. Lett. 78, 3257 (1997). rB = 0.075±0.030 colour favoured colour suppressed Amplitude ratio rD = 0.060±0.003 doubly Cabibbo suppressed Cabibbo favoured EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

g: B±D0K± ADS+GLW method Improvements: add D0 decay mode: D0Kppp adds: 3 observables, 1 unknown strong phase dK3p, 1 well measured rel. decay rate rDK3p add D0 decay mode into CP eigenstates: D0KK/pp (GLW method) adds: 1 observable, 0 unknown Simultaneous fit to all B±D0K± decays (ADS+GLW) LHCb performance: Charged B decays: Neutral B decays: (same method can be applied) Gronau, London, Wyler, PLB. 253, 483 (1991), PLB 265, 172 (1991). Expected event yield / 2fb-1 B/S B-D0[Kp,K3p]K- + c.c. 112k B-D0[Kp,K3p]K- + c.c. 1.4k B-D0CP[KK,pp]K- + c.c. 7.6k 0.6 ~3 ~2 Sensitivity with 2 fb-1: s(g) ~ 5°-15° (depends on strong phase dD) Expected event yield / 2fb-1 B/S B0D0[K+p-]K*0 + c.c. 3.4k B0D0[K-p+]K*0 + c.c. 0.5k B0D0CP[KK,pp]K*0 + c.c. 0.6k <0.3 <1.7 <1.4 Sensitivity with 2 fb-1: s(g) ~ 7°-10° (depends on strong phase dD) EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

g: B±D0K± GGSZ method When D0 decays into a 3- or 4-particle CP Eigenmode: no significant CP violation in D decays D decay model: ‘exclusive’ point-by-point in phase space or ‘inclusive’ (integrating) measure magnitudes (rD) from Dflavour tags phases (dD) from DCP tags choice: D0KS0p+p- (or KS0K+K-)  phase space = Dalitz plot invariant mass: m±= KS0p± Dalitz amplitudes: A(D0KS0p+p-) = f(m+2,m-2) A(D0KS0p-p+) = f(m-2,m+2) B decay amplitudes: A(B-(KSp+p-)DK-)  f(m-2,m+2) + f(m+2,m-2) rB ei(dB-g) A(B+(KSp+p-)DK+)  f(m-2,m+2) + f(m-2,m+2) rB ei(dB+g) With known f : fit simultaneously for: rB, dB, g rB & dB depend on mode: B-DCPK- B-D*CPK- B-DCPK*- Giri, Grossman, Soffer, Zupan, PRD 68, 050418 (2003). many resonances needed m+2 [GeV2/C4] m-2 [GeV2/C4] D0 EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

current Dalitz uncertainty 11% g: B±D0K± GGSZ method Select B decays: “Cartesian parameters”: to better disentangle parameters in fit (x±, y±) = (rB cos (dB±g), rB sin (dB±g)) B± Dalitz plot distribution depends on x±, y± Fit (x±, y±) Dalitz plots: Extract g: BaBar: g = (92 ± 41 ± 11 ± 12)° Belle: f3 = (53 +15 -18 ± 3 ± 9)° LHCb performance: 2g BaBar: 232M BB event yield N(DK+) N(DK-) B±D0(K-p+)K± B±D0CP+(K-K+)K± B±D0CP+(p-p+)K± B±D0CP-(K0Sp0)K± B±D0CP-(K0Sf)K± B±D0CP-(K0Sw)K± 649±29 26±9.. 18±7.. 39±9.. 15±5.. 25±7.. 611±28 70±10 17±7.. 42±9.. 13±4.. 14±6.. x y PRD 73 051105(R) (2006). Sensitivity with 2 fb-1: s(g) ~ 8° current Dalitz uncertainty 11% (to be improved) Expected event yield / 2fb-1 B-(KSp+p-)DK- + c.c. 5k 0.2 < B/S < 1.0 (90% CL) EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

Very rare B decays: BSm+m- Very rare loop decay, sensitive to New Physics: BR 3.4±0.410–9 in SM, can be strongly enhanced in SUSY Current limit from CDF+D0 is: 1 fb–1: 7510–9 (90% CL ) CMSSM: prediction of BR(BSm+m-) wrt. gaugino mass m1/2 ~ a few 10-9 – 10-7: much higher than SM Main issue is background rejection With limited MC statistics, indication that main background is bX, bX SM (C)MSSM ? ~tan6b or ~tan4b 10-9 10-8 10-7 m1/2 [GeV] BR(BSmm) hint from m: g-2 EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

BSm+m- sensitivity Limit at 90% C.L. 5 3 1 year of LHCb 0.05 fb–1  overtake CDF+D0 0.5 fb–1  exclude BR values down to SM Limit at 90% C.L. (only bkg is observed) Integrated Luminosity (fb-1) Uncertainty in background prediction Expected final CDF+D0 Limit BR (x10–9) SM prediction LHCb Sensitivity (signal+bkg is observed) Integrated Luminosity (fb-1) 5 3 BR (x10–9) SM prediction 2 fb–1  3 evidence of SM signal 10 fb–1  >5 observation of SM signal 1 year of LHCb EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

Rare B decays: B0K*0m+m- Suppressed by loop decay: BR ~1.210–6 Forward-Backward Asymmetry AFB(s) in the  rest-frame is sensitive probe of New Physics LHCb sensitivity: 7.7k signal events/2fb–1 (~1yr LHCb) Bbb/S = 0.4 ± 0.1 S0= S(AFB(s)=0): s(S0) = ±0.52 GeV2  determine ratio of Wilson coefficients C7eff/C9eff with 13% stat error (SM) s = (m)2 [GeV2] AFB(s), theory position of S0 integral + – K* B0 q LHCb: 2 fb–1, fast MC S0=4.0 GeV2 AFB(s) s = (m)2 [GeV2] EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

B0K*0m+m- transversity angles Transversity amplitudes: LHCb study for 2 fb-1 Matias hep-ph/0612166. Longitudinal polarisation FL Asymmetry AT(2) SUSY 1 SM NLO SUSY II EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

LHCb Status LHCb Construction on Schedule Muon Calorimeters RICH2 Trackers Magnet RICH1 VELO EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt

Conclusions BSJ/Y(l+l-)f(K+K-): sensitivity on fS with 2 fb-1: s(fS) = ±0.023 rad significant coverage of phase space for NP with 0.2 fb-1 B±D0K± : clean channel, different methods explored sensitivity on g with 2 fb-1: s(g) ~ 5°-15° rare decays : big potential for search for NP BSm+m- : with 2 fb-1  3 evidence of SM signal B0K*0m+m- : with 2 fb-1  s(S0)= ±0.52 GeV2 LHCb waiting for physics data in 2008 many new and exciting physics results in flavour physics (and NP?) stay tuned! EPS 2007, Manchester, 20.07.2007 Stephan Eisenhardt