Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userObservation of D0-D0bar oscillations
160
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report a measurement of the time-dependent ratio of D0->K+pi- to D0->K-pi+ decay rates in D*+-tagged events using 1.0 fb^{-1} of integrated luminosity recorded by the LHCb experiment. We measure the mixing parameters x2=(-0.9+-1.3)x10^{-4}, y=(7.2+-2.4)x10^{-3} and the ratio of doubly-Cabibbo-suppressed to Cabibbo-favored decay rates R_D=(3.52+-0.15)x10^{-3}, where the uncertainties include statistical and systematic sources. The result excludes the no-mixing hypothesis with a probability corresponding to 9.1 standard deviations and represents the first observation of D0-D0bar oscillations from a single measurement.
rate research
Read More
We measure the time dependence of the ratio of decay rates for D0 -> K+ pi- to the Cabibbo-favored decay D0 -> K- pi+. The charge conjugate decays are included. A signal of 3.3 x 10^4 D*+ -> pi+ D0, D0 -> K+ pi- decays is obtained with D0 proper decay times between 0.75 and 10 mean D0 lifetimes. The data were recorded with the CDF II detector at the Fermilab Tevatron and correspond to an integrated luminosity of 9.6 fb-1 for p-pbar collisions at sqrt(s) = 1.96 TeV. Assuming CP conservation, we search for D0-D0bar mixing and measure the mixing parameters to be R_D = (3.51 +/- 0.35) x 10^{-3}, y = (4.3 +/- 4.3) x 10^{-3}, and x^2 = (0.08 +/- 0.18) x 10^{-3}. We report Bayesian probability intervals in the x^2 - y plane and find that the significance of excluding the no-mixing hypothesis is equivalent to 6.1 Gaussian standard deviations, providing the second observation of D0-D0bar mixing from a single experiment.
Measurements of charm mixing parameters from the decay-time-dependent ratio of D0->K+pi- to D0->K-pi+ rates and the charge-conjugate ratio are reported. The analysis uses data, corresponding to 3 fb^{-1} of integrated luminosity, from proton-proton collisions at 7 and 8 TeV center-of-mass energies recorded by the LHCb experiment. In the limit of charge-parity (CP) symmetry, the mixing parameters are determined to be x^2=(5.5 +- 4.9)x10^{-5}, y= (4.8 +- 1.0)x10^{-3}, and R_D=(3.568 +- 0.066)x10^{-3}. Allowing for CP violation, the mixing parameters are determined separately for D0 and D0bar mesons yielding A_D = (-0.7 +- 1.9)%, for the direct CP-violating asymmetry, and 0.75 < |q/p|< 1.24 at the 68.3% confidence level, where q and p are parameters that describe the mass eigenstates of the neutral charm mesons in terms of the flavor eigenstates. This is the most precise determination of these parameters from a single experiment and shows no evidence for CP violation.
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.
We exploit the quantum coherence between pair-produced D0 and D0bar in psi(3770) decays to study charm mixing, which is characterized by the parameters x and y, and to make a first determination of the relative strong phase delta between doubly Cabibbo-suppressed D0 -> K+pi- and Cabibbo-favored D0bar -> K+pi-. We analyze a sample of 1.0 million D0D0bar pairs from 281 pb^-1 of e+e- collision data collected with the CLEO-c detector at E_cm = 3.77 GeV. By combining CLEO-c measurements with branching fraction input and time-integrated measurements of R_M = (x^2+y^2)/2 and R_{WS} = Gamma(D0 -> K+pi-)/Gamma(D0bar -> K+pi-) from other experiments, we find cosdelta = 1.03 +0.31-0.17 +- 0.06, where the uncertainties are statistical and systematic, respectively. In addition, by further including external measurements of charm mixing parameters, we obtain an alternate measurement of cosdelta = 1.10 +- 0.35 +- 0.07, as well as xsindelta = (4.4 +2.7-1.8 +- 2.9) x 10^-3 and delta = 22 +11-12 +9-11 degrees.
The first observation of the decay B0 -> D0bar K+ K- is reported from an analysis of 0.62 fb-1 of pp collision data collected with the LHCb detector. Its branching fraction is measured relative to that of the topologically similar decay B0 -> D0bar pi+ pi- to be BR(B0 -> D0bar K+ K-)/BR(B0 -> D0bar pi+ pi-) = 0.056+-0.011+-0.007, where the first uncertainty is statistical and the second is systematic. The significance of the signal is 5.8 sigma. Evidence, with 3.8 sigma significance, for Bs -> D0bar K+ K- decays is also presented, with a relative branching fraction of BR(Bs -> D0bar K+ K-)/BR(B0 -> D0bar K+ K-) = 0.90+-0.27+-0.20.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
