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Register a new userCPT Violation in $boldsymbol{B^0_s}$--$boldsymbol{bar B^0_s}$ mixing and the measurement of CP Violation in $boldsymbol{B_sto K^+K^-}$
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A simple analysis of time-dependent $B_sto K^+K^-$ transitions, based on recent results from the LHCb experiment, is presented. The benefits of adopting a fully consistent theoretical description of the $B^0_s$--$bar B^0_s$ mixing are stressed. It is shown that bounds on CPT violation in the $B^0_s$--$bar B^0_s$ system can be consistently obtained and that direct CP violation in $B_sto K^+K^-$ can be robustly established, even in the presence of CPT violation in the mixing.
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The three-body charmless hadronic decay $B^0_s rightarrow K^{0}_{rm S} pi^{+}pi^{-}$ provides a number of novel possibilities to search for CP violation effects and test the Standard Model of particle physics. These include fits to the Dalitz-plot distributions of the decay-time-integrated final state, decay-time-dependent (but without initial state flavour tagging) fits to the Dalitz-plot distribution, as well as full decay-time-dependent and flavour tagged fits. The relative sensitivities of these different approaches are investigated.
Measurements are presented of the $CP$ violation observables $S$ and $C$ in the decays of $B^0$ and $overline{B}{}^0$ mesons to the $J/psi K^0_S$ final state. The data sample corresponds to an integrated luminosity of $3.0,text{fb}^{-1}$ collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of $7$ and $8,text{TeV}$. The analysis of the time evolution of $41500$ $B^0$ and $overline{B}{}^0$ decays yields $S = 0.731 pm 0.035 , text{(stat)} pm 0.020 ,text{(syst)}$ and $C = -0.038 pm 0.032 , text{(stat)} pm 0.005,text{(syst)}$. In the Standard Model, $S$ equals $sin(2beta)$ to a good level of precision. The values are consistent with the current world averages and with the Standard Model expectations.
The $B^0_s$ and $B^0$ mixing frequencies, $Delta m_s$ and $Delta m_d$, are measured using a data sample corresponding to an integrated luminosity of 1.0 fb^{-1} collected by the LHCb experiment in $pp$ collisions at a centre of mass energy of 7 TeV during 2011. Around 1.8x10^6 candidate events are selected of the type $B^0_{(s)} to D^-_{(s)} mu^+$ (+ anything), where about half are from peaking and combinatorial backgrounds. To determine the B decay times, a correction is required for the momentum carried by missing particles, which is performed using a simulation-based statistical method. Associated production of muons or mesons allows us to tag the initial-state flavour and so to resolve oscillations due to mixing. We obtain Delta m_s = (17.93 pm 0.22 (stat) pm 0.15 (syst)) ps^{-1}, Delta m_d = (0.503 pm 0.011 (stat) pm 0.013 (syst)) ps^{-1}. The hypothesis of no oscillations is rejected by the equivalent of 5.8 standard deviations for $B^0_s$ and 13.0 standard deviations for $B^0$. This is the first observation of $B^0_s$ mixing to be made using only semileptonic decays.
We determine hadronic matrix elements relevant for the mass and width differences, $Delta M_s$ & $Delta Gamma_s$ in the $B^0_s - bar{B^0_s}$ meson system using fully unquenched lattice QCD. We employ the MILC collaboration gauge configurations that include $u$, $d$ and $s$ sea quarks using the improved staggered quark (AsqTad) action and a highly improved gluon action. We implement the valence $s$ quark also with the AsqTad action and use Nonrelativistic QCD for the valence $b$ quark. For the nonperturbative QCD input into the Standard Model expression for $Delta M_s$ we find $f_{B_s} sqrt{hat{B}_{B_s}} = 0.281(21)$GeV. Results for four-fermion operator matrix elements entering Standard Model formulas for $Delta Gamma_s$ are also presented.
We report a study of the decay $D^0 to K^0_S K^0_S$ using 921~fb$^{-1}$ of data collected at or near the $Upsilon(4S)$ and $Upsilon(5S)$ resonances with the Belle detector at the KEKB asymmetric energy $e^+e^-$ collider. The measured time-integrated $CP$ asymmetry is $ A_{CP}(D^0 to K^0_S K^0_S) = (-0.02 pm 1.53 pm 0.02 pm 0.17) %$, and the branching fraction is $mathcal{B} (D^{0}rightarrow K_{S}^{0}K_{S}^{0})$ = (1.321 $pm$ 0.023 $pm$ 0.036 $pm$ 0.044) $times$ 10$^{-4}$, where the first uncertainty is statistical, the second is systematic, and the third is due to the normalization mode ($D^0 to K_S^0 pi^0$). These results are significantly more precise than previous measurements available for this mode. The $A_{CP}$ measurement is consistent with the standard model expectation.
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