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Time-Integrated CPV

Time-Integrated CPV. CPV in the charm sector is expected to be small in the SM. If it is measured to be above the 0.1% level , it would signal NP. Experimentally we measure the decay rate asymmetry which includes both direct and indirect contributions.

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Time-Integrated CPV

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  1. Time-Integrated CPV • CPV in the charm sector is expected to be small in the SM. If it is measured to be above the 0.1% level, it would signal NP. • Experimentally we measure the decay rate asymmetry which includes both direct and indirect contributions. • New insight on systematics, improve uncertainties  ~(0.2-0.4)%. • Previous asymmetries were~0%with uncertainties~(1-10)% Singly Cabbibbo-suppressed SCS decays allow penguins  can lead to CPV F. Bucella et al., Phys. Rev. D51, 3478 (1995) S. Bianco et al., Riv. Nuovo Cim. 26N7, 1(2003) S. Bianco, F.L. Fabbri, D. Benson, and I. Bigi, Riv., Nuovo Cim. 26N7, 1 (2003). A.A. Petrov, Phys. Rev. D69, 111901 (2004) Y. Grossman, A.L. Kagan, and Y. Nir, Phys. Rev. D75,036008 (2007) = A~0. 01% Brian Meadows, U. Cincinnati TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AAAAAAAAAAAAAAA

  2. Measurements of ACP • Until 2008, systematic limit for precision of ACP was ~1%. 2007 Brian Meadows, U. Cincinnati

  3. D0 K+K-, K+K-0, +- and +-0 • D0’s produced in e+e- collisions at B factories are tagged by the sign of the slow pion from D* decay BaBar introduced a way round two main barriers to the “per mille” level: • Efficiencies fors+ands-are not the same Use DATA to find the asymmetry: • Use (several x106)untagged K -+to map efficiency asymmetry for K –and for+ • Repeat fortagged K -+to mapsasymmetry • D 0 ‘s are produced with asymmetry in * (relative to beam axis) and efficiency depends on * (from Z0/ and higher order effects) • Take average of each cos* range for |cos*| > 0 and < 0 as ACP • Take difference of each cos* range for |cos*| > 0 and < 0 as AFB Brian Meadows, U. Cincinnati

  4. D0 K+K- and +- Arxiv:0807.0148v1 (2008) NEW Phys.Rev.Lett.100:061803 (2008) • No evidence for CPV • Systematic uncertainties ~ 0.1% (Likely scale with luminosity-1/2) !! • No significant difference between KK and  Brian Meadows, U. Cincinnati

  5. D0-+0 and K-K+0 • There are two recent results on the CPV asymmetry measurement, integrated over the 3-body phase space for these channels: • Three search strategies (2 model-independent) for CPV in quasi two-body modes led to upper limit ~2%. Phys.Lett.B662:102-110,2008 532 fb-1 Phys.Rev.D (Accepted) 384 fb-1 Belle’s (earlier paper), did not do this. Babar used the technique described to correct for tracking asymmetries. • No evidence for CPV • Systematic uncertainties ~ 0.2% (Likely scale with luminosity-1/2) !! • No significant difference between KK  0 and  0 Brian Meadows, U. Cincinnati

  6. D+K-K++ Arxiv:0807.4545v1 (2008) 818 pb-1 • CLEO-c used 818 pb-1e+e- at the (3770) – nearD+D-threshold. • Tag one D§ to identify the other one • no asymmetry from D* tagging! • Laboratory system same as CMS • no production asymmetry. • Overall asymmetry • Amplitude analysis of Dalitz plot – integrated asymmetry D+K+K-+ x Tag D - Brian Meadows, U. Cincinnati

  7. CPV in D0-+0 and K-K+0 Phys.Rev.D (Accepted) 384 fb-1 • Exploited potential for extended search within these 3-body modes: • CPV is unlikely to be in all channels – but perhaps in one Search each channel - e.g. D0 0 + 0 • Each channel can be normalized to whole Dalitz plot. Systematic uncertainties from s+ tagging or from production asymmetries become 2nd o`rder effects • CPV is signalled by differences in phase behaviour between D0 and D0. Dalitz plot for these 3-body final states yields information on phase behaviour between channels. • BaBar used three search strategies • Two model-independent searches for CPV in exclusive parts of phase space. • A model-dependent search based on a to fit the Dalitz plot distributions Brian Meadows, U. Cincinnati

  8. Two Model-Independent Searches for CPV in D0-+0 and K-K+0 Phys.Rev.D (TBP, 2008) Dalitz plots for D0 and for D0 are normalized and compared, bin-for-bin Unbiassed frequentist test yields 16.6% conf. level there is no difference. Legendre polynomial moments up to order 8 for D0 and for D0 are normalized and compared, in each channel. Unbiassed frequentist test indicates 23-66% conf. level there are no differences in the various channels. [+-]+ 0 channel [+0]+ - channel Brian Meadows, U. Cincinnati

  9. Model-dependent Search for CPV in D0-+0 and K-K+0 Phys.Rev.D (TBP, 2008) Dalitz plots for D0 and for D0 were fitted to isobar model expansions of interfering amplitudes in each channel. Differences in magnitudes and phases For each amplitude were insignificant. Brian Meadows, U. Cincinnati

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