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1 (what are all those B factory talks really about ?)
Section 5: B mesons (what are all those B factory talks really about ?) :

2 Bo Bo systems Decays of Bo Bo are the same,
so lifetimes of B1 and B2 are similar Two types of neutral B mesons: Bd = (bd) ; Bd = (bd) Bs = (bs) ; Bs = (bs) Difference in B1 and B2 lifetimes is small Difference in B1 and B2 masses is large Oscillation parameter o o

3 Mixing - B0 B0 Dominated by top quark contribution
(and similarly for Bs) o b d W- u, c, t u, c, t _ _ W+ d b - B0 B0 d b u, c, t W- _ _ _ W+ _ _ u, c, t d b Dominated by top quark contribution For Bo For Bo s

4 Bd Mixing EPS,2005 BELLE 152 106 BB . Full B reconstruction
Time-dependent probability for a at t=0 to be observed as or at time t BELLE BB . Full B reconstruction Asymmetry  cos(Dmdt) |Dt| (ps) Dmd : a high precision measurement (~1%) dominated by B factories results Dmd = 0.5090.005 ps-1

5 Amplitude method search:
ms EPS 2005 68%CL 95%CL Dms= 22.2 3.1 ps-1 Dms > 14.4 ps-1 at 95%CL Expectation from fits to the Unitarity Triangle Amplitude method search: LEP, SLD, Tevatron ( )

6 Bs Mixing - xs wtag backgroundst st = 43 fs s DMs= 8fs-1
CDF DMs/Gs = xs <60 SM 22< xs < 31 Si detector & disp. track trigger combine with Bd mixing - xd xs/xd a |Vts/Vtd| (s - theoretical unc.) constrain side of CKM triangle Flavour at Decay Flavour at Production - other B proper time wtag backgroundst LHCb st = 43 fs s DMs= 8fs-1 DMs = 10 ps-1


8 CP Violation in B Decays
TYPES: 1) neutral to CP eigenstates 2) neutral to non-CP eigenstates 3) charged B-decays CP Possibilities: Mixing Decay Interference between mixing and decay Channels: Far too many to discuss! A few well known ‘benchmark channels’

9 BdJ/Ks (CP=-1) J/ ( ) o c b c o o s K  K mixing s d d o
( ) BdJ/Ks (CP=-1) o c b J/ c o o s K K mixing s d d o Look at decay (l+l-)(+-), Br(BdJ/Ks) ~ 5x10-4 Minus for CP odd state

10 ( ) BdJ/Ks (CP=-1) Asymmetry

11 B  charmonium EPS 2005 B0 tag _ B0 tag golden mode C=0 S=sin(2b)
B0  f B0  B0  f B  charmonium (_) B0 tag B0 tag _ Dominant penguin contribution : same weak phase ( no direct CP violation) The only diagram with a different weak phase is suppressed by O(l2) (+OZI) golden mode C=0 S=sin(2b) New BELLE result for J/K0 ( BB) EPS 2005

12 Discovery of Direct CP in B system
Look at B-> K+ - Cf. anti-B->K- + Tree and Penguin Diagrams Contribute Sign of Kaon Tags B rather than anti-B meson


14 Sin(2a) from Bdgp+p- Penguin Pollution BR 5x10-6 Tree only:
Penguin Pollution BR 5x10-6 No sub-mass constraint Other 2 body backgrounds Tree only: Due to Penguin: a, d, |P/T| Hard to interpret in terms of a P in BgKp, or isospin Bgp0p0 Another possibility, clean theory, complex analysis a from Bdgrpgp+p-p0

15 Benchmark g BdgD*-p+ BsgDsK+ - g-2dg 2b + g Tree only BR 10-3
- BdgD*-p+ BsgDsK+ 2b + g Tree only Mixing and decay BR 10-3 But bgu doubly cabibbo suppressed (~ 2% bgc) Bs counterparts g-2dg Similar strength diagrams Larger asymmetry BS BR 10-4 Better Bet (if RICH) Dsp background

16 Brief Angles Prospects Summary
BdgJ/Ks Measured accurately by BaBar/Belle Bdgp+p-, with |P/T| knowledge. Bdgrpgp+p-p0, time dep. Dalitz plot As BdgD*-p+ or BsgDsK+ Bdgp+p- - What is it good for ? Comparing with BsgK+K-  BdgJ/, obtain CP eigenstates from angular correlations Probe higher order unitarity r o o o o o - o o o

17 The Experiments B Factories (2000): TeVatron (2001 ):
BaBar, Belle (also CLEO) TeVatron (2001 ): CDF, D0, (proposed BTev) LHC (start 2007) LHCb (also ATLAS,CMS)

18 Flavour Tagging B Signal B Other B use particles accompanying signal B
e – tagging efficiency w – wrong tagging fraction D=1-2w, Dilution Identify other b hadron - deduce initial flavour Semileptonic decay bgl kaon tag bgcgs jet charge

19 Systematic Errors measure e,e w,w Precision 10-3 Untaggeda f+ / f-
Production Asymmetries Initial fraction b , b e , e e.g. detector response asymmetry in magnetic field w , w Final State acceptance Control Channels e.g. measure e,e w,w Precision 10-3 Untaggeda f+ / f- + -

20 B Factories: BaBar/PEPII, Belle/KEKB
Asymmetric beams boosted B Time difference between B decays  z At decay time on b one bbar (c.f. EPR ‘Paradox’)

21 Why study CP at a hadron collider ?
e+ e- (BaBar) pp(bar) (D0) Rate statistics limited channel Clean environment no additional tracks Initial state B0B0 or B+B- B mesons ~ 20% stot simpler triggering Bs DMs Bs Extracting g Bs J/Yf

22 Hadronic b production h = - ln (tan (q/2))
LHC 1012 bb per year h = - ln (tan (q/2)) 2 < h<5 LHCb/BTeV for larger |h | B boost bg increases rapidly (B factories ~ 108) B quark pair produced preferentially at small q highly correlated

23 LHCb Detector Forward single arm spectrometer
Two RICH detectors for particle ID Multi-level Trigger system, using displaced vertices Precision Silicon Vertex Detector 40MHz beam crossing rate Series of Discs Detectors separated 6cm during injection

24 Bdgp+p- No identification Purity = 9.5% With pion identification
Purity = 85%, Eff. =90%

25 Remarks on CP Violation
Section 6: Concluding Remarks on CP Violation :

26 CKM triangle status, ICHEP 2004
Compatibility obtained between all constraints 2002: first non-trivial compatibility test for CKM triangle Next step to measure alpha and beta angles


28 Final Comments CP violation: a fundamental symmetry broken Next Decade
Good reasons to believe SM is not final answer Sensitive to new physics Next Decade Promises to be v. exciting for CP studies BaBar/Belle , TeVatron, LHC Overconstrain CKM triangle

29 Not the whole picture…. Do mixing CP violation in the lepton sector
Not yet observed Slow oscillations x< 0.01 Sensitive to new physics CP violation in the lepton sector Massive neutrinos  Neutrino mixing between flavour eigenstates to produce mass eigenstates Neutrino Oscillations between 3 famillies and CP phase. Neutrino Factory would produce enough neutrinos for CP violation test. See Paul’s neutrino course

30 Further Reading SLAC-R-504 The BaBar Physics Book,
Chapter 1, A CP Violation Primer CP Violation, Bigi & Sanda, Cambridge University Press, 2000 FERMILAB-Pub-01/197 B Physics at the Tevatron: Run II and Beyond CERN Proceedings of the workshop on Standard Model Physics (and more) at the LHC B Decays Chapter Hep-ph/ , Y. Nir, Lectures at the SLAC Summer Institute (1999)

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