3,821 research outputs found
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, 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 and decays. The impact of background in both decay channels on the measurement of 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 and channels respectively
The decay
In this paper the potential for the discovery of new physics in the exclusive
decay 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
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