6 pages, 4 figures; Submitted to the proceedings of the XLIInd Rencontres de Moriond Electroweak Interactions and Unified Theories, March 10-17 2007, and the XLIInd Rencontres de Moriond QCD and Hadronic Interactions, March 17-24 2007, La Thuile, Italy
We present evidence for D0-D0bar mixing in $D^0 \to K^{+}π^{-}$ decays from 384 fb^{-1} of e+e- colliding-beam data recorded near sqrt(s)=10.6 GeV with the Babar detector at the PEP-II storage rings at SLAC. We find the mixing parameters ${x^{\prime}}^2 = [-0.22 \pm 0.30 (stat.) \pm 0.21 (syst.)] \times 10^{-3}$ and $y^{\prime} = [9.7 \pm 4.4 (stat.) \pm 3.1 (syst.)] \times 10^{-3}$, and a correlation between them of -0.94. This result is inconsistent with the no-mixing hypothesis with a significance of 3.9 standard deviations. We measure $R_{\rm D}$, the ratio of doubly Cabibbo-suppressed to Cabibbo-favored decay rates, to be $[0.303 \pm 0.016 (stat.) \pm 0.010 (syst.)] %$. We find no evidence for CP violation.
Preliminary limits on the D^0 mixing parameter y = ΔΓ/ 2 Γare obtained using about 57.8 fb^-1 of data collected by BaBar in 2000 and 2001:y = (1.4 \pm 1.0 (stat.) +0.6 -0.7 (syst.))%. y is extracted, provided that CP is conserved, by measuring separately the D^0 lifetime for the Cabibbo-suppressed decay modes K- K+, π- π+ and the Cabibbo-favoured mode K- π+. Backgrounds are suppressed by D*-tag and particle identification requirements.
BaBar measurements involving semileptonic decays of B mesons are reviewed. Attention is focused on the extraction of |Vub| and |Vcb| elements of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. Recent results of inclusive and exclusive approaches are presented.
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.) +- 0.0…
We report on our recent measurements of the Cabibbo-Kobayashi-Maskawa CP-violating phase gamma and of related CP-asymmetries and branching fraction ratios. The measurements have been performed on samples of up to 465 million BBbar pairs collected by the BaBar detector at the SLAC PEP-II asymmetric-energy B factory in the years 1999-2007.
The results of several studies of charmed mesons and baryons at BABAR are presented. First, searches for the rare decays D0 --> l+ l- are presented and new upper limits on these processes are established. Second, a measurement of the branching fraction of the isospin-violating hadronic decay Ds*(2112)+ --> Ds+ pi0 relative to the radiative decay Ds*(2112)+ --> Ds+ gamma is made. Third, the decays of DsJ*(2317)+ and DsJ(2460)+ mesons are studied and ratios of branching fractions are measured. Fourth, Cabibbo-suppressed decays of the Lambdac+ are examined and their branching fractions measured r…
We present a study of B- -> D^0_CP K^- decays, where D^0_CP is reconstructed in CP-even channels, based on a sample of 88.8 million Upsilon(4S)->BBbar decays collected with the BaBar detector at the PEP-II e^+e^- storage ring. We measure the ratio of Cabibbo-suppressed to Cabibbo-favored branching fractions Br(B- -> D^0_CP K^-)/Br(B- -> D^0_CP pi^-)= (8.8 +/- 1.6(stat) +/- 0.5(syst))\times 10^{-2} and the CP asymmetry A_CP= 0.07 +/- 0.17(stat) +/- 0.06(syst). We also measure Br(B- ->D0K-)/Br(B- ->D0pi-)=(8.31 +/- 0.35(stat) +/- 0.20(syst))\times 10^{-2} using a sample of 61.0 million BBbar pai…
With 12.3 fb-1 collected by the BaBar experiment in 2001, the mixing parameter y = Delta(Gamma)/(2 Gamma) is determined from the ratio of the D0 lifetimes measured in the D0 --> K- pi+ and in the D0 --> K- K+ decay modes. The preliminary result y = (-1.0 +- 2.2(stat.) +- 1.7(syst.))% is obtained. Also presented is the status of measuring the mixing parameters y and x^2 = [Delta(M)/Gamma]^2 from a simultaneous fit to the time evolution of the decay time distributions of Cabibbo-favored right-sign (D0 --> K- pi+) and doubly Cabibbo-suppressed wrong-sign (D0 --> K+ pi-) decays. The wrong-sign dec…
We report on several studies of charm baryon production and decays by the BaBar collaboration. We confirm previous observations of the $Ξ_c^{'0/+}$, $Ξ_c(2980)^+$ and $Ξ_c(3077)^+$ baryons, measure branching ratios for Cabibbo-suppressed $Λ_c^+$ decays and use baryon decays to study the properties of the light-quark baryons, $Ω^-$ and $Ξ(1690)^0$.
Using data collected with the BaBar detector at PEP-II at SLAC, we report on several tau lepton measurements that are used to determine the modulus of the Cabibbo-Kobayashi-Maskawa matrix element Vus, and to check the Standard Model predictions of lepton universality and CPT conservation.
We report on the measurement of the Cabibbo-Kobayashi-Maskawa angle gamma through a Dalitz analysis of neutral D decays to K0s pi- pi+ in the processes B-+ -> D^(*) K-+ and B-+ -> D K^*-+, D^* -> D pi0, D gamma, with the Babar detector at the SLAC PEP-II e^+ e^- asymmetric-energy collider.
We report on new measurements of the Cabibbo-Kobayashi-Maskawa matrix elements |V_{cb}| and |V_{ub}| with inclusive and exclusive semileptonic B decays, highlighting the recent precision measurements with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC.
We present some recent BABAR measurements of the magnitudes of the elements Vub and Vcb of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix, and of the angles alpha and gamma of the unitary triangle of the standard model of the electroweak interactions. Most of the measurements presented here are based on the full BABAR Y(4S) dataset, consisting of about 467 million B anti-B pairs.
We report on measurements of branching fractions for several hadronic tau decays to final states with kaons, which can be used to determine the strange quark mass and the element |V_us| of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix. The results are obtained from data collected with the BaBar and Belle detectors at the PEP-II and KEKB asymmetric-energy e+e- colliders at SLAC and KEK, respectively, both operating at center-of-mass energies near the Y(4S) resonance.
The BABAR experiment has completed its first year of data-taking during which 21 $fb^{-1}$ of data were accumulated. We present preliminary results on two types of charmless B decays based on this data sample. The first, $B^0 \to K^{*0}γ$, is a so-called electromagnetic penguin. And the second, $B^0 \to h^+h^{'-}$, where $h^{(')}$ can be either a pion or kaon, can come from either penguin diagrams or Cabibbo suppressed tree diagrams.
We search for CP violation in a sample of 4.7x10^4 Cabibbo suppressed D0 -> K+K-pi+pi- decays. We use 470 fb-1 of data recorded by the BaBar detector at the PeP2 asymmetric-energy e+e- storage rings running at center-of-mass energies near 10.6 GeV. CP violation is searched for in the difference between the T-odd asymmetries, obtained using triple product correlations, measured for D0 and D0b decays. The measured At violation parameter is At = (1.0 +- 5.1_sta +- 4.4_sys) x 10^-3.
The BaBar and Belle collaborations have recently found evidence for mixing within the D meson system. We present some of the mixing search techniques used by BaBar and their status as of the beginning of the summer 2007. These have culminated in a measurement in the K decay final state of the D that is inconsistent with the no-mixing hypothesis with a significance of 3.9 standard deviations.
The time-dependent CP asymmetries in fully reconstructed B0 --> D(*)pi/rho decays (new preliminary result), and in partially reconstructed B0 --> D(*)pi decays, are measured with the BaBar detector at the PEP-II asymmetric B factory at SLAC, using 232 million Y(4S) -> BB decays. We combine the above results and, using other measurements and theoretical assumptions, we interpret them in terms of the angles of the unitarity triangle describing the Cabibbo-Kobayashi-Maskawa matrix. We find |sin(2beta+gamma)|>0.64(0.42) at 68%(90%) confidence level using a frequentistic approach and |2beta+gamma|=…
Recent BaBar measurements on lifetime and mixing of B mesons are reported. Various techniques are used, ranging from the full reconstruction of hadronic B decays, to partial reconstruction techniques, and to a totally inclusive approach with dilepton events. The results presented are based on a data sample collected by BaBar during the 1999-2000 data taking, and should be considered as preliminary.
We present results of a search for $D^0$-$\kern 0.2em\bar{\kern -0.2em D}{}^0$~mixing and a measurement of $R_{\rm D}$, the ratio of doubly Cabibbo-suppressed decays to Cabibbo-favored decays, based on an analysis of $D^0 \to K^{+}π^{-}$ decays in 57.1~${fb}^{-1}$ of data collected at or just below the $Υ{(4S)}$ resonance with the {\slshape BABAR} detector at the PEP-II collider. Our results are compatible with no mixing and no $CP$ violation. At the 95% C.L., allowing for CP violation, we find the mixing parameters ${x^{\prime}}^2<0.0022$ and $-0.056<y^{\prime}<0.039$, and the mixing rate $R_…
Evidence from the \babar, Belle and CDF experiments for the phenomenon of \dzdzb\ oscillations is reviewed. A summary is made of the current understanding of the parameters defining the mixing of mass eigenstates that give rise to the oscillations. Results of searches for CP violation induced by mixing, are given, and estimates for the precision of measurements that can be expected in future experiments are made.
Using a sample of four million hadronic Z events collected in ALEPH from 1991 to 1995, the decays D*+ -> D0pi^+_s, with D0 decaying to K-pi+ or to K+pi-, are studied. The relative branching ratio B(D0 -> K+pi-)/B(D0 -> K-pi+) is measured to be (1.84+-0.59(stat.)+-0.34(syst.))%. The two possible contributions to the D0 -> K+pi- decay, doubly cabibbo-suppressed decays and D0-Dbar0 mixing, are disentangled by measuring the proper-time ditribution of the reconstructed D0's. Assuming no interference between the two processes, the upper limit obtained on the mixing rate is 0.92% at 95% CL. The possi…
We overview recent measurements in B -> rho rho decays which are based on data samples collected at the PEP-II and KEKB asymmetric-energy e+e- colliders with the BABAR and Belle detectors. Special emphasis is given to the determination of the CP-violating coefficients A and S from an analysis of B -> rho+ rho- decays. The values of A and S, branching fractions, and longitudinal polarization fractions of B -> rho rho decays are used to constrain the Cabibbo-Kobayashi-Maskawa phase alpha/phi2 using an isospin analysis; the solution consistent with the standard model is 71 deg. < alpha < 113 deg.…
We have searched for mixing in the D0-D0bar system by measuring the decay-time distribution of D0->K+pi- decays. The analysis uses 90 fb^{-1} of data collected by the Belle detector at the KEKB e+e- collider. We fit the decay-time distribution for the mixing parameters x' and y' and also for the parameter R_D, which is the ratio of the rate for the doubly-Cabibbo-suppressed decay D0->K+pi- to that for the Cabibbo-favored decay D0->K-pi+. We do these fits both assuming CP conservation and allowing for CP violation. We use a frequentist method to obtain a 95% C.L. region in the x'^2 - y' plane. …
The $B^0\bar{B^0}$ oscillation frequency $Δm_d$ has been measured with the BaBar detector at the PEP-II asymmetric $B$ factory with different experimental techniques. The discussion here is focused on the recent simultaneous measurement of $Δm_d$ and $τ_{B^0}$ with exclusively reconstructed $B^0 \to D^{*-}l^+ν_l$ decays, based on 23 million $B\bar{B}$ pairs collected by BaBar. The measurements of $Δm_d$ with fully reconstructed hadronic decays and with dilepton events are also reviewed. The average BaBar result is $Δm_d = 0.500 \pm 0.008 \pm 0.006$ $ps^{-1}$.
Presented are selected results of semileptonic B decays at BaBar. Two measurements of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ are reported. One using moments of the hadronic-mass spectrum in inclusive $\bar{B} \to X_{c} \ell^{-} \barν$ decays, and the other, exclusive $\bar{B} \to D \ell^- \barν_{\ell}$ decays. These results are based on data samples of 232 (inclusive $\bar{B} \to X_{c} \ell^{-} \barν$) and 460 (exclusive $\var{B} \to D \ell^- \barν_{\ell}$) million $Υ(4S) \to B\bar{B}$ decays, recorded by the $BaBar$ detector at the PEP-II $e^+e^-$-storage rings. Semileptonic …
We present results of a search for D0-D0bar mixing and doubly-Cabibbo-suppressed decays of the D0 in Fermilab experiment E791, a fixed-target charm hadroproduction experiment. We look for evidence of mixing in the decay chain D* -> pi D0 -> (K pi or K pi pi pi). If the charge of the pion from the D* decay is the same as the charge of the kaon from the D decay (a ``wrong-sign'' event), mixing may have occurred. Mixing can be distinguished from other sources of wrong-sign events (such as doubly-Cabibbo-suppressed decays) by analyzing the distribution of decay times. We see no evidence of mixing.…
Time-dependent B0-antiB0 flavor oscillations and B0 and B+ lifetimes are studied in a sample of fully reconstructed B mesons collected with the BaBar detector, running at the PEP-II asymmetric e+e- B Factory with center-of-mass energies near the Upsilon(4S) resonance. This is the first time that time-dependent mixing and lifetime measurements have been performed at Upsilon(4S) energies.
We report the determination of the Cabibbo-Kobayashi-Maskawa CP-violating angle gamma through the combination of various measurements involving B^{+-} --> D K^{+-}, B^{+-} --> D^{*} K^{+-}, and B^{+-} --> D K^{*+-} decays performed by the BaBar experiment at the PEP-II e^{+}e^{-} collider at SLAC National Accelerator Laboratory. Using up to 474 million B\bar{B} pairs, we obtain gamma = (69 ^{+17}_{-16})^\circ (modulo 180^\circ). The total uncertainty is dominated by the statistical component, with the experimental and amplitude-model systematic uncertainties amounting to +-4^\circ. The corresp…
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 present the measurements of the CKM matrix parameters Vub, Vcb and of the B mixing oscillation frequency with the BaBar experiment at the asymmetric B-factory PEPII. Data were collected in the years 2000-2002 and the total available statistics corresponds to 91 fb-1. The Vub, Vcb measurements utilize both inclusive and exclusive semileptonic decays of the $B$ meson. The Delta(md) parameter is measured by using the time evolution of the B, determined from the flight length difference between the two B mesons.
We report updates on two analyses of inclusive semileptonic B decays based on a dataset of 89 million BB events recorded with the BABAR detector at the Y(4S) resonance. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other B meson. In the first analysis, the measurement of the first and second moment of the hadronic mass distribution in Cabibbo-favored B ->X_c l nu decays allows for the determination of the nonperturbative parameters $\barΛ$ and $λ_1$ of Heavy Quark Effective Theory (HQET) and |Vcb|. In the second anal…
A summary of the results of several recent studies of charm mixing is presented. A number of different methods were used, including the measurement of lifetime ratios for final states of different CP, time dependence of wrong-sign hadronic decays, fits to time-dependent Dalitz plots, and searches for wrong-sign semi-leptonic decays. Taken together, they suggest mixing is of order 1%. The status of searches for indirect CP violation is also reported.
We present a preliminary search for D0--anti-D0 mixing using the decays D0 --> K+ pi- pi0, additionally presenting Dalitz-plot distributions and a measurement of the branching ratio for this mode. A new tagging technique is used to produce the doubly Cabibbo-suppressed Dalitz plot, which in turn is used to motivate the method used for the D-mixing search. We analyze 230.4fb-1 of data collected from the BaBar detector at the PEP-II collider. Assuming CP conservation, we find R_M < 0.054% with 95% confidence, and we estimate that the data are consistent with no mixing at a 4.5% confidence level.…
We present results on semileptonic B decays obtained with the BABAR detector. The large data set accumulated at the PEP-II asymmetric-energy B-Factory allows a new measurement technique, where the hadronic decay of one B meson is fully reconstructed and the semileptonic decay of the recoiling B meson is studied. Traditional analysis techniques of inclusive and exclusive B decays complement this approach with very high statistics data samples. These measurements play an important role in the tests of the description of CP violation in the Standard Model: The determinations of the Cabibbo-Kobaya…
We present an analysis of the decay $D^0 \to K^+π^-$ based on FOCUS data. From a sample of 234 signal events, we find a branching ratio of $\frac{Γ(D^0 \to K^+π^-)}{Γ(D^0 \to K^-π^+)} = (0.429^{+0.063}_{-0.061}\pm 0.027)%$ under the assumptions of no mixing and no CP violation. Allowing for CP violation, we find a branching ratio of $(0.429 \pm 0.063 \pm 0.028)%$ and a \textit{CP} asymmetry of $0.18 \pm 0.14 \pm 0.04$. The branching ratio for the case of mixing with no CP violation is $(0.381^{+0.167}_{-0.163} \pm 0.092)%$. We also present limits on charm mixing.
We describe measurements of CP and CPT violation parameters in B^0B^0bar oscillations, performed at BaBar by using BBbar events collected at the Y(4S) mass peak. These are obtained from two different B-reconstruction methods, namely: searching for two inclusive semileptonic B^0 decays in an event or partially reconstructing one of the B^0 mesons in the D* l nu_l channel. The results are in agreement with one another and with the most recent theoretical calculations in the Standard Model scenario.
Recent results from BaBar and Belle experiments on $B \bar B$ mixing and $\sin 2ϕ_1$ are presented. Accuracy of $Δm_d$ measurements has reached 1.2%. Higher order effects within the Standard Model or possible new physics effect that might appear in the $B \bar B$ mixing through non-zero $ΔΓ/Γ$, CP violation, or $CPT$ violation have been explored. The BaBar and Belle results on $\sin 2ϕ_1$ from the $b \to c \bar{c} s$ modes are in good agreement with each other and a combined result with an accuracy of 8% is in good agreement with a global CKM fit. A simple average of the $\sin 2ϕ_1$ values tha…
The BABAR detector, which operates at the SLAC PEPII asymmetric e+e- collider at energies near the Y(4S) resonance has collected about 23M B-anti-B pairs in year 2000. Based on this data sample, we present the first study of sin(2b), with samples of B^0 --> J/psi K0S, B^0 --> psi(2S) K0S and B^0 --> J/psi K0L decays. The measured value is 0.34+-0.20+-0.05. In addition, we present preliminary measurements of charged and neutral B meson lifetimes and B^0-anti-B^0 oscillation frequency.
With an integrated luminosity of 7.7 fb-1 collected on resonance by BABAR at the PEP-II asymmetric B Factory, we measure the difference in mass between the neutral B eigenstates, Delta(m_d), to be (0.507+/-0.015+/-0.022)x 10^{12} hbar s^{-1} with dileptons events and present preliminary results for the B^0 lifetime, tau(B^0) = 1.55+/-0.05+/-0.07 ps and tau(B^0) = 1.62+/-0.02+/-0.09 ps obtained from partial reconstruction of the two B^0 decay processes respectively B^0-->D^{*-}pi^+ and B^0-->D^{*-} l^+ nu_l.
The BaBar collaboration has analysed 60M BB_ pairs collected at the Upsilon (4S) resonance at the PEP II asymetric collider at SLAC. Using this data sample we have measured the CP violation parameters sin (2beta)=0.75+/- 0.09 (STAT) +/-0.04 (SYST) and lambda =0.92+/- 0.06 (STAT) +/- 0.02 (SYST) from B0 to cc_+K*0 + c.c. decays. From charmless 2-body B decays we measure A_Kpi =-0.05 +/- 0.06 +/- 0.01(-0.14,+0.05), S_pipi = -0.01 +/- 0.37 +/- 0.07(-0.66,+0.62), C_pipi =-0.02 +/- 0.29 +/- 0.07(-0.54,+0.48). A number of B lifetime and mixing parameters, extracted from subsamples of this data set, …
We report the observation of CP violation in the $B^0$ meson system. Using a novel technique for time-dependent measurements, we measure a non-zero value for the CP-violating amplitude $\sin 2β$ at the 4.1 $σ$ level. We also report on precision measurements of the $B^+$ and $B^0$ lifetimes and the $B^0\bar{B}^0$ mixing frequency $Δm_d$ obtained with the same technique and on a first measurement of the time-dependent CP-violating amplitude in $B^0\to π^+π^-$ decays.
In view of the new data from the Daya Bay and RENO collaborations, King has presented a very natural deformation of tri-bimaximal mixing. Here we show that L/E flatness of the e-like event ratio in the atmospheric neutrino data, when coupled with King's observation that the smallest neutrino mixing angle, θ_{13}, seems to be related to the largest quark mixing angle (the Cabibbo angle θ_C), leads to a CP violating tri-bimaximal-Cabibbo mixing. King's tri-bimaximal-Cabibbo mixing follows as a leading order approximation from our result.
Results of recent searches for new physics in CP violation in charm decays from the BABAR experiment are presented. These results include a measurement of $D^0$ - $\bar{D}^0$ mixing and searches for CP violation in two-body $D^0$ decays, a search for CP violation in the charm decays $D^{\pm} \to K^0_S K^{\pm}$ and $D^{\pm}_s \to K^0_S K^{\pm}$, $K^0_S π^{\pm}$, and a search for direct CP violation in the singly-Cabibbo suppressed $D^{\pm} \to K^+ K^- π^{\pm}$ decays. These studies are based on the final dataset collected by BABAR at the PEP-II B factory at SLAC in the period 1999-2008. No evid…
We report on a measurement of the Cabibbo-Kobayashi-Maskawa CP-violating phase gamma through a Dalitz analysis of neutral D decays to K0s pi- pi+ in the processes B-+ -> D(*)K-+, D* -> D pi0, D gamma. Using a sample of 227 million BBbar pairs collected by the BaBar detector, we measure the amplitude ratios rB = 0.12+/-0.08+/-0.03+/-0.04 and rB* = 0.17+/-0.10+/-0.03+/-0.03, the relative strong phases deltaB = 104+/-45+17-21+16-24, and deltaB*= -64+/-41+14-12+/-15 between the amplitudes A(B- -> Dbar(*)0 K-) and A(B- -> D(*)0 K-), and gamma = 70+/-31+12-10+14-11. The first error is statistical, t…
The BaBar detector at the PEP-II asymmetric B Factory at SLAC collected a sample of 23M B-anti-B pairs in the years 1999 and 2000. Using this data sample, we measure the amplitude of the time-dependent CP-violating asymmetry in neutral B decays to the CP eigenstates B0 --> J/psi K0S, B0 --> psi(2S) K0S and B0 --> J/psi K0L. We find a value of sin2beta = 0.34 +/- 0.20 (stat) +/- 0.05 (syst). We also present preliminary measurements of the B^0-anti-B^0 oscillation frequency and of the lifetimes of charged and neutral B mesons.
We report on a measurement of D0-D0bar mixing and a search for CP violation in the D0->K+K-, pi+pi- and K+-pi-+ channels. We use D0's coming from D*+ decays, so that the flavour of the D0 at production is tagged by the charge of the pion that is also emitted. We also use an independent set of D0's coming directly from the hadronization of the charm quark, but in this case the flavour of the charmed meson is not known. We analyze events collected by the BaBar experiment at the PEP-II asymmetric-energy e+e- collider, corresponding to an integrated luminosity of 468 fb-1. We measure the mixing pa…
Mixing and CP violation in charm meson decays provide a unique probe of possible physics beyond the standard model. In this paper, we give a brief review of the current measurements from the BABAR experiment.
We measure the branching ratios of the Cabibbo-suppressed decays $Λ^+_c$ $\to$ $Λ$ $K^+$ and $Λ^+_c$ $\to$ $Σ^{0}$ $K^+$ %(measured with improved accuracy). relative to the Cabibbo-favored decay modes $Λ^+_c$ $\to$ $Λ$ $π^+$ and $Λ^+_c$ $\to$ $Σ^{0}$ $π^+$ to be $ 0.044 \pm 0.004 (\textnormal{stat.}) \pm 0.003 \ (\textnormal{syst.})$ and $ 0.039 \pm 0.005 (\textnormal{stat.}) \pm 0.003 (\textnormal{syst.})$, respectively. We set an upper limit on the branching ratio at 90 % confidence level for $Λ^+_c$ $\to$ $Λ$ $K^+ π^+ π^-$ to be $ 4.1 \times 10^{-2}$ relative to $Λ^+_c$ $\to$ $Λ$ $π^+$ and …
In this proceedings we present a measurement of mixing, and searches for direct and indirect CP asymmetries in the charm sector using the full \babar data sample of $469 \invfb$. Searches for direct CP asymmetries have been performed in the $D^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$, $D_s^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$, $D_s^{\pm}\to K^0_{\scriptscriptstyle S} π^\pm$, and $D^{\pm} \to K^+ K^- π^\pm$ decay channels, with both model-dependent and model-independent approaches being exploited for the last mode. The mixing measurement and the search for indirect CP asymmetry have b…
CP violation in B0B0bar mixing is characterized by the value of the parameter |q/p| being different from 1, and the Standard Model predicts this difference to be smaller than 10^{-3}. We present a measurement of this parameter using a partial reconstruction of one of the B mesons in the semileptonic channel D*- l+ nu_l, where only the hard lepton and the soft pion from the D*- --> D0bar pi- decay are reconstructed. The flavor of the other B is determined by means of lepton tagging. The determination of |q/p| is then performed with a fit to the proper time difference of the two B decays. We use…
We have measured the branching fractions of the Cabibbo-suppressed decays $Λ^+_c$ $\to$ $Λ^{0}$ $K^+$ and $Λ^+_c$ $\to$ $Σ^0$ $K^+$ %(measured with improved accuracy). relative to the Cabibbo-allowed decay modes $Λ^+_c$ $\to$ $Λ^{0}$ $π^+$ and $Λ^+_c$ $\to$ $Σ^0$ $π^+$ to be $ 0.044 \pm 0.004 (\textnormal{stat.}) \pm 0.002 (\textnormal{syst.})$ and $ 0.040 \pm 0.005 (\textnormal{stat.}) \pm 0.004 (\textnormal{syst.})$, respectively. We also present the first observation of $Λ^+_c$ $\to$ $Λ^{0}$ $K^+ π^+ π^-$ and have measured the branching fraction relative to $Λ^+_c$ $\to$ $Λ^{0}$ $π^+$ to be…
We report the measurement of the Cabibbo-Kobayashi-Maskawa CP-violating angle $γ$ through a Dalitz plot analysis of neutral $D$ meson decays to $K_S^0 π^+ π^-$ and $K_S^0 K^+ K^-$ produced in the processes $B^\mp \to D K^\mp$, $B^\mp \to D^{*} K^\mp$ with $D^* \to D π^0,D γ$, and $B^\mp \to D K^{*\mp}$ with $K^{*\mp} \to K_S^0 π^\mp$, using 468 million $B\bar{B}$ pairs collected by the BABAR detector at the PEP-II asymmetric-energy $e^+e^-$ collider at SLAC. We measure $γ=(68 \pm 14 \pm 4 \pm 3)^\circ$ ({\rm mod $180^\circ$}), where the first error is statistical, the second is the experimenta…
We present an updated study of charm mixing and the relative strong phase between doubly Cabibbo-suppressed D0 --> K+pi- and Cabibbo-favored D0bar --> K+pi- decay amplitudes using 3 x 10^6 quantum-correlated D0D0bar pairs from 818 pb^-1 of e+e- collision data collected with the CLEO-c detector at E_cm=3.77 GeV.
The parameter $y_{CP}$ is used to characterize mixing in the $D^0$-$\bar{D}{}^0$ meson system. To determine $y_{CP}$, one measures the effective decay width of a $D^0$ or $\bar{D}{}^0$ decaying to a $CP$ eigenstate, relative to the effective width for a decay to a Cabibbo-favored, flavor-specific final state. When using $y_{CP}$ to extract information about $D^0$-$\bar{D}{}^0$ mixing and $CP$ violation, the decay width of the Cabibbo-favored decay is usually assumed to equal $1/τ$, the reciprocal of the $D^0$ lifetime. However, there is a small correction to this that should be taken into acco…
Using a data sample of 62 million \FourS\to B\Bbar decays collected between 1999 and 2001 by the BaBar detector at the PEP2 asymmetric-energy B Factory at SLAC we study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the flavour of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin(2 beta), is derived from the decay time distributions. We measure sin(2 beta) = 0.75 \pm 0.09 (stat) \pm 0.04 (syst) and |λ| = 0.92 \pm 0.06 (sta…
We report a measurement of the time-dependent ratio of $D^0\to K^+π^-$ to $D^0\to K^-π^+$ decay rates in $D^{*+}$-tagged events using 1.0\,fb$^{-1}$ of integrated luminosity recorded by the LHCb experiment. We measure the mixing parameters $x'^2=(-0.9\pm1.3)\times10^{-4}$, $y'=(7.2\pm2.4)\times10^{-3}$ and the ratio of doubly-Cabibbo-suppressed to Cabibbo-favored decay rates $R_D=(3.52\pm0.15)\times10^{-3}$. The result excludes the no-mixing hypothesis with a probability corresponding to 9.1 standard deviations and represents the first observation of charm mixing from a single measurement
A review of the latest results on charm lifetimes and D-mixing is presented. The e+e- collider experiments are now able to measure charm lifetimes quite precisely, however comparisons with the latest results from fixed-target experiments show that possible systematic effects could be evident. The new D-mixing results from the B-factories have changed the picture that is emerging. Although the new world averaged value of y_CP is now consistent with zero, there is still a very interesting and favoured scenario if the strong phase difference between the Doubly-Cabibbo-suppressed and the Cabibbo-f…
We present the results of a search for a dark photon decaying to $e^+e^-$ or $μ^+μ^-$ in the \babar\ detector. We find no evidence for such a dark photon and set upper limits on the dark mixing as a function mass, tightening the constraints on the parameter space of several dark sector theories.
