Mixing in the D0 - D0bar system at BaBar

We report a preliminary result for D0-D0bar mixing and the doubly Cabibbo suppressed decay rate R_D based on an analysis of D0 -> K+ pi- decays from 57.1 inverse fb of data collected at or just below the Y(4S) resonance with the BaBar detector at the PEP-II collider. We set 95% confidence limits for the mixing parameters x'^2 and y' and find that our result is compatible with no mixing and no CP violation. In the limit of no mixing we find the doubly Cabibbo suppressed decay rate R_D = (0.357 +- 0.022 (stat.) +- 0.027 (syst.))% and the CP violating asymmetry A_D = 0.095 +- 0.061 (stat.) +- 0.083 (syst.).Comment: 5 pages, 2 postscript figues, contributed to the proceedings of the Frontier Science 2002 conferenc

Using Double Tagging to measure the Performance of the Same Side Kaon Tagger in Data

This note describes a method for the measurement of the wrong-tag fraction of the Same Side Kaon tagger, $\omega_{ss}$ in data using the Double Tagging procedure. The importance of such a measurement is explained and the method of Double Tagging described. This measurement was carried out using samples from reconstructed $Bs -> Ds\pi$ and $Bs -> Ds\mu\nu$ decays. The impact of background in both decay channels on the measurement of $\omega_{ss}$ was also studied. A general way of handling tagger correlations is presented. Finally, the Double Tagging measurement and the correlation investigation are performed on the present Monte Carlo data and the results presented. Results show that with 2fb-1 of data, the Double Tagging procedure can be used to measure the SS Kaon wrong-tag fraction to a statistical accuracy of 3.6% and 1.2% for the $Bs -> Ds\pi$ and $Bs -> Ds\mu\nu$ channels respectively

The Bˉd→Kˉ∗0μ+μ−\bar{B}_d \to \bar{K}^{*0} \mu^+ \mu^- decay

In this paper the potential for the discovery of new physics in the exclusive decay $\bar{B}_d \to \bar{K}^{*0} \mu^+ \mu^-$ is discussed. Attention is paid to constructing observables which are protected from uncertainties in QCD form factors and at the same time observe the symmetries of the angular distribution. We discuss the sensitivity to new physics in the observables including the effect of CP-violating phases.Comment: 6 pages, 5 figures, Third Workshop on Theory, Phenomenology and Experiments in Heavy Flavour Physics, Capri 201

Determination of the wrong sign decay rate D0 -> K+pi- and the sensitivity to D0-D0bar mixing

The D0 meson can decay to the wrong sign K+pi- state either through a doubly Cabibbo suppressed decay or via mixing to the D0bar state followed by the Cabibbo favoured decay D0bar -> K+ pi-. We measure the rate of wrong sign decays relative to the Cabibbo favoured decay to (0.383 +- 0.044 +- 0.022)% and give our sensitivity to a mixing signal

Electron Identification with the ATLAS Detector at the Large Hadron Collider

For the ATLAS experiment at LHC identification of leptons will be of extreme importance. Here is presented the general physics motivation for electron identification together with the approach used in ATLAS. Special emphasis is put on the use of a transition radiation detector to improve the rejection of jets provided by the calorimeters and tracking alone. A general overview is given of how electron identification will be used in the physics analysis. The analysis of data from a prototype of the transition radiation tracker shows a detector which can work at a high luminosity hadron collider

The exclusive B to K*(to K pi) l+ l- decay: CP conserving observables

We study the K* polarization states in the exclusive 4-body B meson decay B to K* (to K pi) l+ l- in the low dilepton mass region working in the framework of QCDF. We review the construction of the CP conserving transverse and transverse/longitudinal observables AT2, AT3, and AT4. We focus here, on analyzing their behaviour at large recoil energy in presence of right-handed currents.Comment: 7 pages, 3 figures, invited talk at Flavianet Meeting, Kazimierz, Poland, July, 200

New observables in the decay mode anti-B --> anti-K*0 l+ l-

We discuss the large set of observables available from the angular distributions of the decay anti-B --> anti-K*0 l+ l-. We present a NLO analysis of all observables based on the QCD factorization approach in the low-dilepton mass region and an estimate of \Lambda/m_b corrections. Moreover, we discuss their sensitivity to new physics. We explore the experimental sensitivities at LHCb (10 fb^-1) and Super-LHCb (100 fb^-1) based on a full-angular fit method and explore the sensitivity to right handed currents. We also show that the previously discussed transversity amplitude A_T^(1) cannot be measured at the LHCb experiment or at future B factory experiments as it requires a measurement of the spin of the final state particles.Comment: 30 pages, 14 figures. Changes: Typos in (4.3) and (4.11) corrected, analysis, results and figures unchange

More Benefits of Semileptonic Rare B Decays at Low Recoil: CP Violation

We present a systematic analysis of the angular distribution of Bbar -> Kbar^\ast (-> Kbar pi) l^+ l^- decays with l = e, mu in the low recoil region (i.e. at high dilepton invariant masses of the order of the mass of the b-quark) to account model-independently for CP violation beyond the Standard Model, working to next-to-leading order QCD. From the employed heavy quark effective theory framework we identify the key CP observables with reduced hadronic uncertainties. Since some of the CP asymmetries are CP-odd they can be measured without B-flavour tagging. This is particularly beneficial for Bbar_s,B_s -> phi(-> K^+ K^-) l^+ l^- decays, which are not self-tagging, and we work out the corresponding time-integrated CP asymmetries. Presently available experimental constraints allow the proposed CP asymmetries to be sizeable, up to values of the order ~ 0.2, while the corresponding Standard Model values receive a strong parametric suppression at the level of O(10^-4). Furthermore, we work out the allowed ranges of the short-distance (Wilson) coefficients C_9,C_10 in the presence of CP violation beyond the Standard Model but no further Dirac structures. We find the Bbar_s -> mu^+ mu^- branching ratio to be below 9*10^-9 (at 95% CL). Possibilities to check the performance of the theoretical low recoil framework are pointed out.Comment: 18 pages, 3 fig.; 1 reference and comment on higher order effects added; EOS link fixed. Minor adjustments to Eqs 4.1-4.3 to match the (lower) q^2-cut as given in paper. Main results and conclusions unchanged; v3+v4: treatment of exp. uncert. in likelihood-function in EOS fixed and constraints from scan on C9,C10 updated (Fig 2,3 and Eqs 3.2,3.3). Main results and conclusions absolutely unchange