We present updated measurements of time-dependent CP asymmetries in fully reconstructed neutral B decays containing a charmonium meson. The measurements reported here use a data sample of (465+/-5) million Upsilon(4S)->BBbar decays collected with the Babar detector at the PEPII asymmetric energy e+e- storage rings operating at the SLAC National Accelerator Laboratory. The time-dependent CP asymmetry parameters measured from JpsiKs, JpsiKL, Psi(2S)Ks, Chi_c1Ks, eta_cKs and JpsiK*0 decays are: C_f = 0.024+/-0.020(stat)+/-0.016(syst) and -η_f S_f = 0.687+/-0.028(stat)+/-0.012(syst).
We perform the first three-dimensional measurement of the amplitudes of $B\toψ{(2S)}K^*$ and $B\toχ_{c1}K^*$ decays and update our previous measurement for $B\to{J\mskip -3mu/\mskip -2muψ\mskip 2mu}K^*$. We use a data sample collected with the {\slshape BABAR} detector at the PEP-II storage ring, representing 232 million produced $B{\kern 0.18em\bar{\kern -0.18em B}}$ pairs. The longitudinal polarization of decays to the $1^{++} χ_{c1}$ meson together with a $K^*$ meson, is found to be larger than that for the decay to the $1^{--} Ψ$ mesons. No direct CP-violating charge asymmetry is observed.
Recent measurements of sin2Beta and cos2Beta using b --> ccbars decays are presented using data collected by the BaBar experiment at the PEP-II asymmetric-energy B-factory.
Recent results in the field of Heavy Quarkonia are reviewed, with results either providing new precision measurements or addressing key unanswered questions.
In a search for B --> ccbar gamma K decays with the BaBar detector, where ccbar includes J/psi and psi(2S), and K includes K+, Ks, and K*(892), we find evidence for X(3872) --> J/psi gamma and X(3872) --> psi(2S) gamma with 3.6 sigma and 3.5 sigma significance, respectively. We measure the product of branching fractions BR(B+ --> X(3872) K+) x BR(X(3872) --> J/psi gamma) = (2.8 +/- 0.8(stat.) +/- 0.2(syst.)) x 10^(-6) and BR(B+ --> X(3872) K+) x BR(X(3872) --> psi(2S) gamma) = (9.9 +/- 2.9(stat.) +/- 0.6(syst.)) x 10^(-6).
The rate of gluons splitting into $c \bar{c}$ pairs in hadronic $Z$ decays is measured using the data sample collected by ALEPH from 1991 to 1995. The selection is based on the identification of leptons (electrons and muons) originating from semileptonic charm decays, and on the topological properties of signal events. The result derived from the selected sample is $g_{c \bar{c}}=(3.26 \pm 0.23 \rm{(stat)} \pm 0.42 \rm{(syst)}) %$
We present an updated measurements of time-dependent CP asymmetries in fully reconstructed neutral B decays to several CP eigenstates containing a charmonium meson. The measurements use a data sample of (347.5 +/- 3.8) x 10^{6} $\FourS \to B\Bbar$ decays collected with the babar detector at the PEP-II B factory between 1999 and 2006. We determine sin2beta = 0.710 +/- 0.034(stat) +/- 0.019(syst) and |λ| = 0.932 +/- 0.026(stat) +/- 0.017(syst). Both of these results are preliminary.
We present results on time-dependent CP asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 227 million Upsilon(4S) -> BBbar decays collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The amplitude of the CP asymmetry, sin2Beta in the Standard Model, is derived from decay-time distributions from events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other $B$ meson is determined to be either a B0 or B0bar from its decay products. We measure sin2Beta = 0.7…
The inclusive charm hadron semileptonic branching fractions B(c to e) and B(c to mu) in Z to ccbar events have been determined using 4.4 million hadronic Z decays collected with the OPAL detector at LEP. A charm-enriched sample is obtained by selecting events with reconstructed D*+- mesons. Using leptons found in the hemisphere opposite that of the D*+- mesons, the semileptonic branching fractions of charm hadrons are measured to be B(c to e) = 0.103 +-0.009 +0.009 -0.008 and B(c to mu) = 0.090 +-0.007 +0.007 -0.006 where the first errors are in each case statistical and the others systematic.…
The production of charmed particles by Sigma- of 340 Gev/c momentum was studied in the hyperon beam experiment WA89 at the CERN-SPS, using the Omega-spectrometer. In two data-taking periods in 1993 and 1994 an integrated luminosity of 1600 microb^-1 on copper and carbon targets was recorded. From the reconstruction of 930 +- 90 charm particle decays in 10 decay channels production cross sections for D, antiD, Ds and Lambdac were determined in the region xF>0. Assuming an A^1 dependence of the cross section on the nucleon number, we calculate a total ccbar production cross section of sigma(x_F …
The data set collected with the ALEPH detector from 1991 to 1995 at LEP has been analysed to measure the charm forward-backward asymmetry at the Z. Out of a total of 4.1 million hadronic Z decays, about 36000 high momentum D*+, D+ and D0 decays were reconstructed, of which 80% originate from Z -> ccbar events...
We have analyzed 116 fb^-1 of data collected by the BABAR detector for Xic0 production. In this paper we describe the observation of Xic0 production from ccbar continuum and from B decays, with the Xic0 decaying into (Xi- pi+) and (Omega- K+) modes. The ratio of the branching fractions of the Xic0 decays into these two final states measured in the ccbar continuum is: B(Xic0 -> Omega- K+) / B(Xic0 -> Xi- pi+) = 0.296 +- 0.018 (stat.) +- 0.030 (sys.). All results in this note are preliminary.
We propose a new explanation for the longstanding puzzle of the tiny branching fraction of psi' -> rho pi relative to that for J/psi -> rho pi. In the case of J/psi, we argue that this decay is dominated by a higher Fock state in which the ccbar pair is in a color-octet ^3S_1 state and via annihilate process ccbar -> qqbar. In the case of the psi', we argue that the probability for the ccbar pair in this higher Fock state to be close enough to annihilate is suppressed by a dynamical effect related to the small energy gap between the mass of the psi' and the DDbar threshold.
We present preliminary results of a study of the two-body B-meson decays to a charmonium state (ccbar) and a K+ or K*0(892) meson using a sample of about 349 fb-1 of data collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. Here ccbar indicates either the eta_c state, reconstructed in the K_S K+- pi-+ and K+K-pi0 decay channels, or the h_c state, reconstructed in its decay to eta_c gamma. We measure BR(B0 -> eta_c K*0)=(6.1+-0.8_stat +- 1.1_syst) * 10-4, BR(B+ -> h_c K+) * BR(h_c -> eta_c gamma)<5.2 * 10-5 and BR(B0 -> h_c K*0) * BR(h_c -> eta_c gamma)<2.41 * 10…
Based on an a high statistics e+e- -> ccbar data sample, we report on the inclusive rate for charmed baryons to decay into / particles using charm-event tagging. We select e+e- -> ccbar events which have a clear anti-charm tag and measure the / content in the hemisphere opposite the tag (charge conjugate modes are implicit). This allows us to determine the product branching fraction: B(/)=B(c->Theta_c)*B(Theta_c->/\X), where Theta_c represents a sum over all charmed baryons produced in e+e- fragmentation at sqrt(s)=10.5 GeV, given our specific tags. We obtain B(/)=(1.87+/-0.03+/-0.33)%
We present a review of the measurements of the CKM angle beta (phi_1) by the BaBar and Belle experiments at the asymmetric-energy e+e- B Factories PEP-II and KEKB. The angle beta (phi_1) is measured by time-dependent CP analyses of neutral B meson decays in a Upsilon(4S)->BBbar system, where one B meson is fully reconstructed in a final state that can be accessed to by both B0 and B0bar, usually a CP eigenstate. This angle has been measured at a high precision through B0-> (ccbar)K0 channels. We also review another tree-dominated decay B0-> D(*)0 h0 (h0 = pi0, eta^{'}, omega); tree decays with…
Hadronic Z0 decays with identified electrons or muons have been used to measure the forward-backward asymmetries of e^+e^- --> Z0 --> bbbar and e^+e^- --> Z0 --> ccbar events. The asymmetries at three centre-of-mass energies, and the average B mixing parameter, chi, are determined in a simultaneous fit to events with one or two lepton candidates.
We present a new measurement of the time-dependent CP asymmetry of B0->D*+D*- decays using (471+-5) million BBbar pairs collected with the BaBar detector at the PEP-II B Factory at the SLAC National Accelerator Laboratory. Using the technique of partial reconstruction, we measure the time-dependent CP asymmetry parameters S=-0.34+-0.12+-0.05$ and C=+0.15+-0.09+-0.04. Using the value for the CP-odd fraction R_perp=0.158+-0.028+-0.006, previously measured by BaBar with fully reconstructed B0->D*+D*- events, we extract the CP-even components S+=-0.49+-0.18+-0.07+-0.04 and C+=+0.15+-0.09+-0.04. In…
The LHCb experiment will search for New Physics in Bs mixing. The Bs mixing phase will be extracted from the measurement of the time-dependent CP asymmetry in exclusive Bs decays governed by the b -> ccbar s quark-level transition. Large New Physics effects can be discovered or excluded with the data collected during the very first physics run of LHC. Based on Monte Carlo simulations of the LHCb detector, the expected sensitivity with 2 inverse fb on the CP-violation parameter phi_s is sigma(phi_s) = 0.022.
The X(3872) and Z(4430) are candidates of tetraquark state with a ccbar pair. We present results from Belle recently updated for the mass, branching fractions etc. in different production/decay processes of the X(3872). Results from a Dalitz analysis for B --> Z(4430) K --> psi' pi^+- K are also presented.
We present an analysis of inclusive Omega_c^0 baryon production and decays in 230.5 fb^-1 of data recorded with the BABAR detector at the PEP-II asymmetric-energy e+ e- collider at the Stanford Linear Accelerator Center. Omega_c^0 baryons are reconstructed in four final states (Omega- pi+, Omega- pi+ pi0, Omega- pi+ pi+ pi-, Xi- K- pi+ pi+) and the ratios of branching fractions for these final states are measured. We also measure the momentum spectrum of the Omega_c^0 baryons in the e+ e- center-of-mass frame. From the spectrum, we observe Omega_c^0 production from B decays and in ccbar events…
Using 13.6/fb of continuum two-jet e+e- -> ccbar events collected with the CLEO detector, we have searched for baryon number correlations at the primary quark level. We have measured the likelihood for a /\c+ charmed baryon to be produced in the hemisphere opposite a /\c- relative to the likelihood for a /\c+ charmed baryon to be produced opposite an anticharmed meson Dbar; in all cases, the reconstructed hadrons must have momentum greater than 2.3 GeV/c. We find that, given a /\c- (reconstructed in five different decay modes), a /\c+ is observed in the opposite hemisphere (0.72+/-0.11)% of th…
The production rates of D*+-, Ds*+-, D+-, D0 / D0bar, Ds+, and Lambda_c in Z to ccbar decays are measured using the LEP I data sample recorded by the ALEPH detector. The fractional energy spectrum of the D*+- is well described as the sum of three contributions: charm hadronisation, b hadron decays and gluon splitting into a pair of heavy quarks. The probability for a c quark to hadronise into a D*+ is found to be f(c to D*+) = 0.233 +- 0.010 (stat.) +- 0.011 (syst.). The average fraction of the beam energy carried by D*+- mesons in Z to cc events is measured to be < X_E (D*+-) >_cc = 0.4878 +-…
We present a measurement of the direct CP violating asymmetry in the decay B0 -> K+pi- using 227 x 10^6 Y(4S) -> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we observe a total signal yield of n(K-pi+) + n(K+pi-) = 1606 +- 51 decays and measure the asymmetry [n(K-pi+)-n(K+pi-)]/[n(K-p+-)+n(K+pi-)] = -0.133+-0.030 (stat) +- 0.009 (syst). The probability of observing such an asymmetry in the absence of direct CP violation is 1.3 x 10^-5, corresponding to 4.2 standard deviations.
In data taken with the NA48 experiment at the CERN SPS in 1999, 730 candidates of the weak radiative hyperon decay Xi0 -> Lambda gamma have been found with an estimated background of 58+-8 events. From these events the Xi0 -> Lambda gamma decay asymmetry has been determined to alpha(Xi0 -> Lambda gamma) = -0.78 +- 0.18_stat +- 0.06_syst, which is the first evidence of a decay asymmetry in Xi0 -> Lambda gamma. The branching fraction of the decay has been measured to be Br(Xi0 -> Lambda gamma) = (1.16 +- 0.05_stat +- 0.06_syst) x 10^-3.
Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement of the weak decay-asymmetry parameter alpha(Lambdac) in Lambdac --> Lambda pi decay. Comparing particle with antiparticle decays, we obtain the first measurement of the CP violation parameter : A = [alpha(Lambdac)+alpha(antiLambda_c)]/[alpha(Lambdac)-alpha(antiLambda_c)]. We obtain alpha(Lambdac)=-0.78+-0.16+-0.13 and A = -0.07+-0.19+-0.12 where errors are statistical and systematic.
A precise measurement of the direct CP violating charge asymmetry parameter $A_g$ in $K^\pm\toπ^\pmπ^+π^-$ decays by the NA48/2 experiment at CERN SPS is presented. The experiment has been designed not to be limited by systematic uncertainties in the asymmetry measurement. A preliminary result for the charge asymmetry $A_g=(-1.3\pm2.3)\times 10^{-4}$ has been obtained with a sample of $3.11\times 10^9$ selected events corresponding to the full collected statistics. The precision of the result is limited by the statistics used.
We present a preliminary measurement of the time-dependent CP asymmetry in B0 --> K*0 (K_S0 pi0) gamma decays based on 431 x 10^6 Upsilon(4S) --> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC. In a sample containing 316 +/- 22 signal events we measure S_{K* gamma} = -0.08 +/- 0.31 +/- 0.05 and C_{K* gamma} = -0.15 +/- 0.17 +/- 0.03. The uncertainties are statistical and systematic, respectively.
We present an update on total and partial branching fractions and on CP asymmetries in the semi-inclusive decay B -> Xs l+l-. Further, we summarize our results on branching fractions and CP asymmetries for semi-inclusive and fully-inclusive B -> Xs gamma decays. We present the first result on the CP asymmetry difference of charged and neutral B -> Xs gamma$ decays yielding the first constraint on the ratio of Wilson coefficients Im (C8/C7).
We present the first measurement of the CP violating charge asymmetry in $B^\pm \to μ^\pm ν_μ{D}^0$ decays using the full Run II integrated luminosity of 10.4 fb$^{-1}$ in proton-antiproton collisions collected with the D0 detector at the Fermilab Tevatron Collider. We measure a difference in the yield of $B^-$ and $B^+$ mesons in these decays by fitting the reconstructed invariant mass distributions. This results in an asymmetry of $A^{μD^{0}} =\left[ -0.14 \pm 0.20 \right]\%$, which is consistent with standard model predictions.
As a followup to the latest BABAR amplitude analysis of the decay $B^+ \rightarrow K^+ K^- K^+$, we investigate the $K^+ K^-$ invariant-mass dependence of the CP asymmetry and compare it to that obtained by the LHCb collaboration. The results are based on a data sample of approximately $470 \times 10^6 B\bar{B}$ decays, collected with the BABAR detector at the PEP-II asymmetric-energy $B$ factory at the SLAC National Accelerator Laboratory.
We have measured the weak decay asymmetry parameters ($\aLC $) for two \LC\ decay modes. Our measurements are $\aLC = -0.94^{+0.21+0.12}_{-0.06-0.06} $ for the decay mode $Λ_c^+ \to Λπ^+ $ and $\aLC = -0.45\pm 0.31 \pm 0.06$ for the decay mode $Λ_c \to Σ^+π^0 $. By combining these measurements with the previously measured decay rates, we have extracted the parity-violating and parity-conserving amplitudes. These amplitudes are used to test models of nonleptonic charmed baryon decay.
We present a measurement of the direct $CP$-violating charge asymmetry in $D_s^\pm \to ϕπ^{\pm}$ decays where the $ϕ$ meson decays to $K^+K^-$, using the full Run II data set with an integrated luminosity of 10.4 fb$^{-1}$ of proton-antiproton collisions collected using the D0 detector at the Fermilab Tevatron Collider. The normalised difference $A_{CP}$ in the yield of $D_s^+$ and $D_s^-$ mesons in these decays is measured by fitting the difference between their reconstructed invariant mass distributions. This results in an asymmetry of $A_{CP} =\left[ -0.38 \pm 0.27 \right]%$, which is the m…
A study of CP violation in $B\to J/ψK^*(K_S^0π^0)$ decays by time dependent angular analysis is discussed. Status of time independent analyses for other $B\to VV$ decays is also reported. The data used for the analyses are taken with the Belle detector at KEK.
We have studied the rare weak radiative hyperon decay Cascade0-->Sigma0/gamma in the KTeV experiment at Fermilab. We have identified 4045 signal events over a background of 804 events. The dominant Cascade0-->Lambda/pi0 decay, which was used for normalization, is the only important background source. An analysis of the acceptance of both modes yields a branching ratio of BR(Cascade0-->Sigma0/gamma)=(3.34 +/- 0.05 +/- 0.09) x 10^(-3). By analyzing the final state decay distributions, we have also determined that the Sigma0 emission asymmetry parameter for this decay is alpha = -0.63 +/- 0.09.
The fraction of Z to bbbar events in hadronic Z decays has been measured by the OPAL experiment using the data collected at LEP between 1992 and 1995. The Z to bbbar decays were tagged using displaced secondary vertices, and high momentum electrons and muons. Systematic uncertainties were reduced by measuring the b-tagging efficiency using a double tagging technique. Efficiency correlations between opposite hemispheres of an event are small, and are well understood through comparisons between real and simulated data samples. A value of Rb = 0.2178 +- 0.0011 +- 0.0013 was obtained, where the fi…
We present a measurement of the muon charge asymmetry from W boson decays using 0.3 fb^{-1} of data collected at \sqrt{s}=1.96 GeV between 2002 and 2004 with the D0 detector at the Fermilab Tevatron ppbar Collider. We compare our findings with expectations from next-to-leading-order calculations performed using the CTEQ6.1M and MRST04 NLO parton distribution functions. Our findings can be used to constrain future parton distribution function fits.
The decay B0 -> J/psi K0_S is reconstructed with J/psi -> e+ e- or mu+ mu- and K0_S -> pi+ pi-. From the full ALEPH dataset at LEP1 of about 4 million hadronic Z decays, 23 candidates are selected with an estimated purity of 71%. They are used to measure the CP asymmetry of this decay, given by sin 2beta in the Standard Model, with the result sin 2beta = 0.84 +0.82-1.04 +-0.16. This is combined with existing measurements from other experiments, and increases the confidence level that CP violation has been observed in this channel to 98%.
We report improved measurements of the partial rate asymmetry (Acp) in B -> h h decays with 140fb^-1 of data collected with the Belle detector at the KEKB e+e- collider. Here h stands for a charged or neutral pion or kaon and in total five decay modes are included: K-+ pi+-, K0s pi-+, K-+ pi0, pi-+ pi0 and K0s pi0. The flavor of the last decay mode is determined from the accompanying B meson. Using a data sample 4.7 times larger than that of our previous measurement, we find Acp(K-+ pi+-) -0.088+-0.035+-0.013, 2.4 sigma from zero. Results for other decay modes are also presented.
Based on a sample of $58\times10^6J/ψ$ decays collected with the BESII detector at the BEPC, the $\barΛ$ decay parameter $α_{\barΛ}$ for $\barΛ\to \bar p π^+$ is measured using about 9000 $J/ψ\toΛ\barΛ\to p \bar p π^+π^-$ decays. A fit to the joint angular distributions yields $α_{\barΛ}(\barΛ\to \bar pπ^+)=-0.755\pm0.083\pm0.063$, where the first error is statistical, and the second systematic.
We present updated measurements of the CP-violating parameters S_pipi and C_pipi in B0 -> pi+pi- decays. Using a sample of 227 million Y(4S) -> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we observe 467 +- 33 signal decays and measure S_pipi = -0.30 +- 0.17 (stat) +- 0.03 (syst), and C_pipi = -0.09 +- 0.15 (stat) +- 0.04 (syst).
We report an improved measurement of the B+ -> D+ D0bar and B0 -> D0 D0bar decays based on 657 10^6 BBar events collected with the Belle detector at KEKB. We measure the branching fraction and charge asymmetry for the B+ -> D+ D0bar decay: B(B+ -> D+ D0bar)=(3.85 +- 0.31 +- 0.38) 10^{-4} and Acp(B+ -> D+ D0bar)=0.00 +- 0.08 +- 0.02, where the first error is statistical and the second is systematic. We also set the upper limit for the B0 -> D0 D0bar decay: B(B0 -> D0 D0bar)< 0.43 10^{-4}at 90% CL.
We present the first study of the time-dependent CP-violating asymmetry in B0 -> J/psi pi0 decays using e+e- annihilation data collected with the BaBar detector at the Upsilon(4S) resonance during the years 1999-2002 at the PEP-II asymmetric-energy B Factory at SLAC. Using approximately 88 million BBbar pairs, our results for the coefficients of the cosine and sine terms of the CP asymmetry are C_(J/psi pi0) = 0.38 +/- 0.41 (stat) +/- 0.09 (syst) and S_(J/psi pi0) = 0.05 +/- 0.49 (stat) +/- 0.16 (syst).
The charge asymmetry has been measured using $19,039~W$ decays recorded by the CDF detector during the 1992-93 run of the Tevatron Collider. The asymmetry is sensitive to the ratio of $d$ and $u$ quark distributions to $x<0.01$ at $Q^2 \approx M_W^2$, where nonperturbative effects are minimal. It is found that of the two current sets of parton distributions, those of Martin, Roberts and Stirling (MRS) are favored over the sets most recently produced by the CTEQ collaboration. The $W$ asymmetry data provide a stronger constraints on $d/u$ ratio than the recent measurements of $F_2^{μn}/F_2^{μp}…
We measure the CP-violating asymmetries in decays to the D0 -> K+K- and D0 -> pi+pi- CP eigenstates using 540 fb^{-1} of data collected with the Belle detector at or near the Upsilon(4S) resonance. Cabibbo-favored D0 -> K-pi+ decays are used to correct for systematic detector effects. The results, A_{CP}^{KK} = (-0.43 +- 0.30 +- 0.11)% and A_{CP}^{pipi} = (+0.43 +- 0.52 +- 0.12)%, are consistent with no CP violation.
We present preliminary results of a time-dependent measurement of CP-violating asymmetry in fully reconstructed B0->D^(*)+-pi-+ decays in a data sample of approximately 88 million Y(4S)->BB decays collected with the BaBar detector at the PEP-II asymmetric-energy B factory at SLAC. We interpret the results in terms of the angles of the Cabibbo-Kobayashi-Maskawa unitarity triangle, and set the bound |sin(2beta+gamma)|>0.69 at 68% confidence level. We exclude sin(2beta+gamma) = 0 at 83% confidence level.
The CP violating asymmetry asl is studied with a sample of Bs0 or Bs0bar semi-muonic decays in proton-proton collisions at a centre-of-mass energy of 7 TeV at LHCb with an integrated luminosity of 1 fb^-1. The final state studied is Dsμ, with Ds reconstructed in the final state ϕπ. The Dsμ yields are summed over untagged Bs0 and Bs0bar initial states, and integrated with respect to decay time. Data driven methods have been developed to measure all the efficiency ratios needed to determine asl from the measured raw asymmetry. We obtain asl= (-0.24+/-0.54+/-0.33)%, where the first uncertainty is…
We describe a measurement of the charge asymmetry of leptons from W boson decays in the rapidity range 0<|y_l|<2.5 using W --> enu, munu events from 110+/-7 pb^{-1}of data collected by the CDF detector during 1992-95. The asymmetry data constrain the ratio of d and u quark momentum distributions in the proton over the x range of 0.006 to 0.34 at Q2 \approx M_W^2. The asymmetry predictions that use parton distribution functions obtained from previously published CDF data in the central rapidity region (0.0<|y_l|<1.1) do not agree with the new data in the large rapidity region (|y_l|>1.1).
We present our first study of the time-dependent CP-violating asymmetry in B0 --> J/psi pi0 decays using e^+e^- annihilation data collected with the BABAR detector at the Y(4S) resonance during the years 1999--2002 at the PEP-II asymmetric-energy B Factory at SLAC. With about 88 million B Bbar pairs, our preliminary results for the coefficients of the cosine and sine terms of the CP asymmetry are C_{J/psi pi0} = 0.38 +/- 0.41 (stat) +/- 0.09 (syst) and S_{J/psi pi0} = 0.05 +/- 0.49 (stat) +/- 0.16 (syst).
Using the CLEO II detector at the Cornell Electron Storage Ring we have measured the $Ξ_c^{0}$ decay asymmetry parameter in the decay $Ξ_c^{0} \to Ξ^{-} π^+$. We find $α_{Ξ_c^{0}} α_Ξ = 0.26 \pm 0.18{(stat)}^{+0.05}_{-0.04}{(syst)}$, using the world average value of $α_Ξ = -0.456 \pm 0.014$ we obtain $α_{Ξ_c^{0}} = -0.56 \pm 0.39{(stat)}^{+0.10}_{-0.09}{(syst)}$. The physically allowed range of a decay asymmetry parameter is $-1<α<+1$. Our result prefers a negative value: $α_{Ξ_c^{0}}$ is $<0.1$ at the 90% CL. The central value occupies the middle of the theoretically expected range but is not…
We describe a measurement of the direct CP asymmetry between inclusive b -> s gamma and bbar -> sbar gamma decays. This asymmetry is expected to be less than 0.01 in the Standard Model, but could be enhanced up to about 0.10 by new physics contributions. We use a sample of 89 million BB pairs recorded with the BaBar detector at PEP-II, from which we reconstruct a set of 12 exclusive b -> s gamma final states containing one charged or neutral kaon and one to three pions. We measure an asymmetry of A_CP(b -> s gamma) = 0.025 +/- 0.050(stat.) +/- 0.015(syst.), corresponding to an allowed range of…
We present updated measurements of time-dependent CP asymmetries in fully reconstructed neutral B decays containing a charmonium meson. The measurements reported here use a data sample of $(465\pm 5)\times 10^6$ $Υ(4S) \to B \bar{B}$ decays collected with the BABAR detector at the PEP-II $B$ factory. The time-dependent CP asymmetry parameters measured from $J/ψK_S^0$, $J/ψK_L^0$, $ψ(2S) K_S^0$, $χ_{c1} K_S^0$, $η_c K_S^0$, and $J/ψK^{*0}$ decays are \begin{eqnarray} C_f &=& 0.026 \pm 0.020(stat) \pm 0.016(syst), S_f &=& 0.691 \pm 0.029(stat) \pm 0.014(syst). \end{eqnarray}
We report an improved measurement of the partial-rate CP asymmetry in B+ => K0pi+ and B- => K0bar pi- decays. The analysis is based on a data sample of 85 million BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e+ e- storage ring. We measure Acp(K0pi+-) = 0.07^{+0.09 +0.01}_{-0.08 -0.03}, where the first and second errors are statistical and systematic, respectively; the corresponding 90% confidence-level interval is -0.10 < Acp(K0pi+-) < 0.22 .
We present a measurement of the branching fraction and time-dependent CP violation parameters for B0 -> D*+ D*- Ks decays. We also obtain an upper limit on the product branching fraction for the possible two-body decay, B0 -> Ds1+(2536) D*-. These results are obtained from a 414 fb-1 data sample that contains 449e10^6 BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e+e- collider.
We present a measurement of the time-integrated flavor-specific semileptonic charge asymmetry in the decays of Bs mesons that have undergone flavor mixing, a^s_ls, using B_s^0 (barB_s^0) -> D_s^-/+ mu^+/- X decays, with D_s^-/+ -> phi pi^-/+ and phi K^+ K^-, using 10.4 fb^-1 of proton-antiproton collisions collected by the D0 detector during Run II at the Fermilab Tevatron Collider. A fit to the difference between the time-integrated D_s^-$ and D_s^+ mass distributions of the B_s^0 and barB^0_s candidates yields the flavor-specific asymmetry a^s_ls = [-1.12 pm 0.74 (stat) +/-0.17 (syst)]% whic…
We report the observation of the decay $B^- \to D_{π^+π^-π^0} K^-$, where $D_{π^+π^-π^0}$ indicates a neutral $D$ meson detected in the final state $π^+π^-π^0$, excluding $K_S π^0$. This doubly Cabibbo-suppressed decay chain can be used to measure the CKM phase $γ$. Using about 229 million $e^+e^- \to B \bar B$ events recorded by the BaBar experiment at the PEP-II $e^+e^-$ storage ring, we measure the branching fraction ${\cal B}(B^- \to D_{π^+π^-π^0} K^-) = (5.5 \pm 1.0 {\rm(stat.)} \pm 0.7 {\rm(syst.)})\times 10^{-6}$ and the decay rate asymmetry $A = 0.02 \pm 0.16 {\rm(stat.)} \pm 0.03 {\rm…
We report a measurement of the decay B0 --> rho0 pi0, using 386 x 10^6 BB-bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We detect 51^{+14}_{-13} signal events with a significance of 4.2 standard deviations, including systematic uncertainties, and measure the branching fraction to be B(B0 --> rho0 pi0) = (3.12^{+0.88}_{-0.82} (stat) +/- 0.33 (syst) ^{+0.50}_{-0.68} (model)) x 10^{-6}. We also perform the first measurement of direct CP violating asymmetry in this mode.
The longitudinal polarization, the transverse polarization, and the forward-backward asymmetry of Lambda baryons have been measured using a sample of 4.34 million hadronic Z^0 decays collected with the OPAL detector at LEP between 1990 and 1995. These results are important as an aid to the understanding of hadronization mechanisms. Significant longitudinal polarization has been observed at intermediate and high momentum. For x_E = 2 E_{Lambda}/\sqrt{s}) > 0.3, the longitudinal polarization has been measured to be -32.9 +/- 5.5(stat) +/- 5.2(syst)%. We have observed no transverse polarization. …
We have measured the CP asymmetry A_CP = [BF(b -> s gamma) - BF(bbar -> sbar gamma)]/ [BF(b -> s gamma) + BF(bbar -> sbar gamma)] to be A_CP = (-0.079 +/- 0.108 +/- 0.022)(1.0 +/- 0.030), implying that, at 90% confidence level, A_CP lies between -0.27 and +0.10. These limits rule out some extreme non-Standard Model predictions, but are consistent with most, as well as with the Standard Model.
