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Physics 222 UCSD/225b UCSB

Physics 222 UCSD/225b UCSB. Lecture 7 Mixing & CP violation (3 of 3) Today, we focus on how to measure things, and what the present knowledge is from the combination of theory and experiment. Take 2 sources as references: David MacFarlane at SSI 2002 Soeren Prell at Lepton-Photon 2009.

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Physics 222 UCSD/225b UCSB

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  1. Physics 222 UCSD/225b UCSB Lecture 7 Mixing & CP violation (3 of 3) Today, we focus on how to measure things, and what the present knowledge is from the combination of theory and experiment. Take 2 sources as references: David MacFarlane at SSI 2002 Soeren Prell at Lepton-Photon 2009

  2. CKM Matrix Element Magnitudes ν ν e- e- e- Vud Vus Vub ν ν ν n K B p π π e- e- e- Vcb Vcd Vcs ν D Bd D π D K Vtd W Vts Vtb b Bd Bs Bs Bd t Lepton Photon 2009 Expt. Status of the CKM Matrix (S.Prell) 2

  3. Why does this matter? Heavy Quark Symmetry predicts that the B -> D* transition in B -> D* l nu has trivial form factor for the part of phase space when the D* is at rest in the B restframe. However, this also leads to minimal pT for the slow pion in the D* -> D pi decay. |Vcb| is theoretically most accurately extracted from experimental data where it is experimentally most difficult.

  4. Luminosity accumulated by Belle reached 1000/fb on November 29th 2009.

  5. β from b →(cc) s decays BaBar, PRD 79,072009 (2009) statistically limited Theor. clean measurement of |S| = sin2β with B → J/ψ K0, J/ψ K*, ψ(2S)KS, ηcKS, & χc1KS by BaBar and Belle Lepton Photon 2009 Expt. Status of the CKM Matrix (S.Prell) 22

  6. Lepton-photon 2009 Dalitz analysis now clearly dominates the precision.

  7. Basic idea: b -> u transition with c-bar quark from virtual W interferes with b -> c transition, IFF one chooses a decay of the D meson that is common for D and anti-D meson. The resonance structure then provides the CP conserving “phase analyzer” to measure gamma from the interference. Poluektov @ EPS’09

  8. Global CKM Fit All constraints Other constraints CKM angles • Consistency of angles • Consistency of angles and sides from global fit • Overall good fit (CKMFitter: global p-value 45%) • ~2σ tension between sin2β and εK / Vub • correction to εK will make it worse (Buras, Guadagnoli, PRD78, 033005 (2008)) Lepton Photon 2009 Expt. Status of the CKM Matrix (S.Prell) 29

  9. Future directions • Ever more precise measurement of: • sin2 from J/ Ks •  from Dalitz analysis • Measurements of processes that only occur at 2nd order weak interaction in standard model • B -> s l+ l- • B -> s nu nubar • Measurements of helicity suppressed decays • B to mu+mu- • CP violation in the Bs system

  10. βs from Bs → J/ψФ decays New physics in BsBs mixing CDF/PHYS/BOTTOM/CDFR/9787, DØ Note 5928-CONF D0 and CDF measure βs with angular dependent fit to decay time distributions of Bs → J/ψФ • Simultaneous fit for ΔΓs and βs • SM predicts βs very small (~0.02) • sensitive to new physics in Bs mixing • Prospects • D0 and CDF working on updates with 2x samples • LHCb sensitivity with 0.5 fb-1: σ(βs) = 0.02 Lepton Photon 2009 Expt. Status of the CKM Matrix (S.Prell) 31

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