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 measurements of the branching fractions of the decays, D-->K^0_{S,L}pi. The measured asymmetry shows that B(D^0--> K^0_S pi^0) is not equal to B(D^0--> K^0_L pi^0), as expected. We also find that B(D^+ --> K^0_S pi^+) is statistically compatible with B(D^+ --> K^0_L pi^+). Lastly, we present a recent measurement of the branching fraction of the doubly Cabibbo-suppressed decay, D^+ --> K^+ pi^0.
Using data collected by the high energy photoproduction experiment FOCUS at Fermilab we study the doubly and singly Cabibbo suppressed decays D+ and Ds+ --> K+ pi+ pi-. Branching ratios and Dalitz plot analyses are performed.
Using data collected with the BESII detector at $e^{+}e^{-}$ storage ring Beijing Electron Positron Collider, the measurements of relative branching fractions for seven Cabibbo suppressed hadronic weak decays $D^0 \to K^- K^+$, $π^+ π^-$, $K^- K^+ π^+ π^-$ and $π^+ π^+ π^- π^-$, $D^+ \to \bar{K^0} K^+$, $K^- K^+ π^+$ and $π^- π^+ π^+$ are presented.
The branching fractions for the inclusive Cabibbo-favored ~K*0 and Cabibbo-suppressed K*0 decays of D mesons are measured based on a data sample of 33 pb-1 collected at and around the center-of-mass energy of 3.773 GeV with the BES-II detector at the BEPC collider. The branching fractions for the decays D+(0) -> ~K*0(892)X and D0 -> K*0(892)X are determined to be BF(D0 -> K*0X) = (8.7 +/- 4.0 +/- 1.2)%, BF(D+ -> ~K*0X) = (23.2 +/- 4.5 +/- 3.0)% and BF(D0 -> K*0X) = (2.8 +/- 1.2 +/- 0.4)%. An upper limit on the branching fraction at 90% C.L. for the decay D+ -> K*0(892)X is set to be BF(D+ -> K…
We report the observation of the doubly Cabibbo-suppressed decay $D^+\to K^+ π^- π^+$ in data from Fermilab charm hadroproduction experiment E791. With a signal of 59 \pm 13 events we measured the ratio of the branching fraction for this mode to that of the Cabibbo-favored decay $D^+\to K^- π^+ π^+$ to be $B(D^+ \to K^+ π^- π^+) / B(D^+ \to K^- π^+ π^+) = (7.7 \pm 1.7 \pm 0.8) \times 10^{-3}$. A Dalitz plot analysis was performed to search for resonant structures.
We report the first observation of the doubly Cabibbo-suppressed decay $D^+_s\to K^+K^+π^-$ using 605 fb$^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The branching ratio with respect to its Cabibbo-favored counterpart $\mathcal{B}(D^+_s\to K^+K^+π^-)$ / $\mathcal{B}(D^+_s\to K^+K^-π^+)$ is (0.229$\pm0.028\pm$0.012)%, where the first uncertainty is statistical and the second is systematic. We also report a significantly improved measurement of the doubly Cabibbo-suppressed decay $D^+\to K^+π^+π^-$, with a branching ratio $\mathcal{B}(D^+\to K…
We study the decay of Ds meson into final states involving a Ks and report the discovery of Cabibbo suppressed decay modes Ds -> Kspi-pi+pi+ (179 +/- 36 events) and Ds -> Kspi+ (113 +/-26 events). The branching ratios for the new modes are Gamma(Ds -> Kspi-pi+pi+)/Gamma(Ds -> KsK-pi+pi+) = 0.18 +/- 0.04 +/- 0.05 and Gamma(Ds -> Kspi+)/Gamma(Ds -> KsK+) = 0.104 +/- 0.024 +/- 0.013.
We report the observation of the Cabibbo-suppressed decays \lcpkk\ and \lcpphi\ using data collected with the CLEO II detector at CESR. The latter mode, observed for the first time with significant statistics, is of interest as a test of color-suppression in charm decays. We have determined the branching ratios for these modes relative to \lcpkpi\ and compared our results with theory.
We present a measurement of the branching fraction for the doubly-Cabibbo-suppressed decay D+ to K+ pi0, using 281 pb-1 of data accumulated with the CLEO-c detector on the psi(3770) resonance. We find B(D+ to K+ pi0) = (2.28 +- 0.36 +- 0.15 +- 0.08) times 10^{-4}, where the first uncertainty is statistical, the second is systematic, and the last error is due to the uncertainty in the reference mode branching fraction.
We present a measurement of the branching fraction for the doubly-Cabibbo-suppressed decay D+ to K+ pi0, using 281 pb-1 of data accumulated with the CLEO-c detector on the psi(3770) resonance. We find B(D+ to K+ pi0) = (2.25 +- 0.36 +- 0.15 +- 0.07) times 10^{-4}, where the first uncertainty is statistical, the second is systematic, and the last error is due to the uncertainty in the reference mode. The results presented in this document are preliminary.
Using a 13.7 fb-1 data sample collected with the CLEO II and II.V detectors, we report new branching fraction measurements for two Cabibbo-suppressed decay modes of the D+ meson: BR(D+ -> pi+ pi0) = (1.31 +/- 0.17 +/- 0.09 +/- 0.09) x 10^(-3)and BR(D+ -> K+ K0bar) = (5.24 +/- 0.43 +/- 0.20 +/- 0.34) x 10^(-3) which are significant improvements over past measurements. The errors reflect statistical and systematical uncertainties as well as the uncertainty in the absolute D+ branching fraction scale. We also set the first 90% confidence level upper limit on the branching fraction of the doubly C…
We have observed the decay of the $B^-$ meson into $D^0 K^-$, using 3.3 million $B\bar B$ pairs collected with the CLEO II detector at the Cornell Electron Storage Ring. We find the branching fractions of this decay to be suppressed relative to the decay into $D^0 π^-$ by $0.055 \pm 0.014 \pm 0.005$.
We report the first observation of the Cabibbo-suppressed charm baryon decay Xi_c+ -> p K- pi+. We observe 150 +- 22 events for the signal. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600 GeV/c Sigma- beam. The branching fractions of the decay relative to the Cabibbo-favored Xi_c+ -> Sigma+ K- pi+ and Xi_c+ -> X- pi+ pi+ are measured to be B(Xi_c+ -> p K- pi+)/B(Xi_c+ -> Sigma+ K- pi+) = 0.22 +- 0.06 +- 0.03 and B(Xi_c+ -> p K- pi+)/B(Xi_c+ -> X- pi+ pi+) = 0.20 +- 0.04 +- 0.02, respectively.
Using a data sample corresponding to 13.7 fb^-1 collected with the CLEO II and II.V detectors, we report new branching fraction measurements for two Cabibbo-suppressed decay modes of the D^+ meson: Br(D^+ to pi^+ pi^0) = (1.3 +/- 0.2) x 10^-3 and Br(D^+ to \bar{K}^0 K^+) = (5.2 +/- 0.6) x 10^-3 which are significant improvements over past measurements. The errors include statistical and systematical uncertainties as well as the uncertainty in the absolute D^+ branching fraction scale. We also set the first 90% confidence level upper limit on the branching fraction of the doubly Cabibbo-suppres…
A phenomenological analysis of $D\to Kπ$ and $D_s^+\to K K $decays including both Cabibbo-favored and doubly-Cabibbo-suppressed modes have been presented by employing the present experimental data. SU(3) symmetry breaking effects from the decay constants and form factors have been taken into account in the analysis. Three asymmetries, $R(D^0)$, $R(D^+)$, and $R(D_s^+)$, which are generated through interference between Cabbibo-favored and doubly- Cabibbo-suppressed decays, are estimated. Theoretical results agree well with the current measurements.
Using 385 fb^-1 of e^+e^- collision data collected at center-of-mass energies around 10.6 GeV, we search for time-integrated CP violation in the singly Cabibbo-suppressed decays D0/D0bar --> pi^- pi^+ pi^0 and D0/D0bar --> K^- K^+ pi^0. Our model-independent and model-dependent analyses show no evidence of CP violation in these decays. The intermediate amplitudes include well-defined flavor states [e.g., rho(770)^+- pi^-+, K*(892)^+- K^-+] and CP-odd eigenstates [e.g., rho(770)^0 pi^0, phi(1020) pi^0]. With the null results of the previous analyses for CP-even eigenstates D0/D0bar --> K^+ K^- …
Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement for the branching ratios of the Cabibbo-suppressed decay modes D0-->Pi-Pi+ and D0-->K-K+. We measured: Gamma(D0-->K-K+)/Gamma(D0-->Pi-Pi+) = 2.81 +/- 0.10(stat) +/- 0.06(syst), Gamma(D0-->K-K+)/Gamma(D0-->K-Pi+) = 0.0993 +/- 0.0014(stat) +/- 0.0014(syst), and Gamma(D0-->Pi-Pi+)/Gamma(D0-->K-Pi+) = 0.0353 +/- 0.0012 (stat) +/- 0.0006(syst). These values have been combined with other experimental data to extract the ratios of isospin amplitudes and the phase shifts for the D-->KK and D-->PiPi decay channels.
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…
Cabibbo-suppressed decays $B \to D^{(*)} K^-$ using a 10.4 fb$^{-1}$ data sample accumulated at the $Υ(4S)$ resonance with the Belle detector at the KEKB $e^+ e^-$ storage ring. The high-momentum particle identification system of Belle is used to isolate signals for $B\to D^0 K^-$, $D^+K^-$, $D^{*0}K^-$ and $D^{*+}K^-$ from the $B\to D^{(*)}π^-$ decay processes which have much larger branching fractions. We report ratios of Cabibbo-suppressed to Cabibbo-favored branching fractions of: ${\cal B}(B^- \to D^0 K^-)/{\cal B}(B^- \to D^0π^-) = 0.079\pm0.009\pm0.006$; ${\cal B}(\bar{B^0} \to D^+ K^-)…
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. …
We report the first observation of two Cabibbo-suppressed decay modes, Xi_c+ -> Sigma+ pi- pi+ and Xi_c+ -> Sigma- pi+ pi+. We observe 59+/-14 over a background of 87, and 22+/-8 over a background of 13 events, respectively, for the signals. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600GeV/c Sigma- beam. The branching ratios of the decays relative to the Cabibbo--favored Xi_c+ -> Xi- pi+ pi+ are measured to be B(Xi_c+ -> Sigma+ pi- pi+)/B(Xi_c+ -> Xi- pi+ pi+) = 0.48+/-0.20, and B(Xi_c+ -> Sigma- pi+ pi+)/B(Xi_c+ ->…
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.…
We present measurements of the Cabibbo-suppressed decays Lambda_c^+ --> Lambda0 K+ and Lambda_c^+ --> Sigma0 K+ (both first observations), Lambda_c^+ --> Sigma+ K+ pi- (seen with large statistics for the first time), Lambda_c^+ --> p K+ K- and Lambda_c^+ --> p phi (measured with improved accuracy). Improved branching ratio measurements for the decays Lambda_c^+ --> Sigma+ K+ K- and Lambda_c^+ --> Sigma+ phi, which are attributed to W-exchange diagrams, are shown. We also present the first evidence for Lambda_c^+ --> Xi(1690)^0 K+ and set an upper limit on the non-resonant decay Lambda_c^+ --> …
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_…
Using 281/pb of data collected with the CLEO-c detector at the psi(3770) resonance, we have studied Cabibbo-suppressed decays of D mesons to final states with two kaons. We present results for the absolute branching fractions of the modes D^0 --> K^+ K^-, D^0 --> K^0_S K^0_S, and D^+ --> K^+ K^0_S. We measure B(D^0 --> K^+ K^-) = (4.08 +- 0.08 +- 0.09) x 10^-3, B(D^0 --> K^0_S K^0_S) = (1.46 +- 0.32 +- 0.09) x 10^-4, and B(D^+ --> K^+ K^0_S) = (3.14 +- 0.09 +- 0.08) x 10^-3. We also determine the ratio B(D^0 --> K^+ K^-)/B(D^0 --> pi^+ pi^-) = 2.89 +- 0.05 +- 0.06. For each measurement, the fi…
Using $2.93 \rm fb^{-1}$ of $e^+e^-$ collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, the first observation of the doubly Cabibbo-suppressed decay $D^+\to K^+π^+π^-π^0$ is reported. After removing decays that contain narrow intermediate resonances, including $D^+\to K^+η$, $D^+\to K^+ω$, and $D^+\to K^+ϕ$, the branching fraction of the decay $D^+\to K^+π^+π^-π^0$ is measured to be $(1.13 \pm 0.08_{\rm stat} \pm 0.03_{\rm syst})\times 10^{-3}$. The ratio of branching fractions of $D^+\to K^+π^+π^-π^0$ over $D^+\to K^-π^+π^+π^0$ is found to be $(1.81\pm0…
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 …
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 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 analyze the weak processes of anti-triplet charmed baryons decaying to octet baryons and mesons with the SU(3) flavor symmetry and topological quark diagram scheme. We study the decay branching ratios without neglecting the contributions from ${\cal O}(\overline{15})$ for the first time in the SU(3) flavor symmetry approach. The fitting results for the Cabibbo allowed and suppressed decays of $Λ_{c}^+$ are all consistent with the experimental data. We predict all singly Cabibbo suppressed decays. In particular, we find that ${\cal B}(Λ_c^+\to p π^0)=(1.3\pm0.7)\times 10^{-4}$, which is slig…
Using data collected on the psi(3770) resonance and near the Ds*+ Ds- peak production energy by the CLEO-c detector, we study the decays of the possible D->PP modes and report measurements of or upper limits on all branching fractions for Cabibbo-favored, singly-Cabibbo-suppressed, and doubly-Cabibbo-suppressed D->PP decays except modes involving K0L (and except D0->K+ pi-). We normalize with respect to the Cabibbo-favored D modes, D0->K- pi+, D+->K- pi+ pi+, and Ds+->K+ K0S.
A definite relative phase and amplitude exists between the doubly-Cabibbo-% suppressed amplitude for $D^0 \to \ko M^0$ and the Cabibbo-favored amplitude for $D^0 \to \ok M^0$, where $M^0 = (π^0,η,η')$: $A(D^0 \to \ko M^0) = - \tan^2 θ_C A(D^0 \to \ok M^0)$. Here $θ_C$ is the Cabibbo angle. This relation, although previously recognized (for $M^0 = π^0$) as a consequence of the U-spin subgroup of SU(3), is argued to be less sensitive to corrections involving SU(3) breaking than related U-spin relations involving charged kaons or strange $D$ mesons. A corresponding relation between $D^+ \to \ko π…
Using 281 pb^-1 of data collected with the CLEO-c detector, we report on first observations and new measurements of Cabibbo-suppressed decays of D mesons to 2, 3, 4, and 5 pions. Branching fractions of previously unobserved modes are measured to be: B(D^0\to pi^+pi^-pi^0pi^0)=(9.9\pm0.6\pm0.7\pm0.2\pm0.1)x10^-3, B(D^0\toπ^+π^+π^-π^-π^0)=(4.1\pm0.5\pm0.2\pm0.1\pm0.0)x10^-3, B(D^+\toπ^+π^0π^0)=(4.8\pm0.3\pm0.3\pm0.2)x10^-3, B(D^+\toπ^+π^+π^-π^0)=(11.6\pm0.4\pm0.6\pm0.4)x10^-3, B(D^0\toηπ^0)=(0.62\pm0.14\pm0.05\pm0.01\pm0.01)x10^-3, and B(D^0\toωπ^+π^-)=(1.7\pm0.5\pm0.2\pm0.0\pm0.0)x10^-3. The un…
Taking into account that the scalar $a_0(980)$ can be dynamically generated from the pseudoscalar-pseudoscalar interaction within the chiral unitary approach, we have studied the single Cabibbo-suppressed process $D^+\to π^+π^0η$. We find clear peaks of $a_0(980)^+$ and $a_0(980)^0$ in the $π^+η$ and $π^0η$ invariant mass distributions, respectively. The predicted Dalitz plots of $D^+\to π^+π^0η$ also manifest the significant signals for $a_0(980)^+$ and $a_0(980)^0$ states. The uncertainties of the results due to the free parameters are also discussed. Our study shows that the process $D^+\to…
Branching ratios for the dominant Cabibbo-suppressed decays of the $τ$ lepton have been measured by CLEO~II in $e^+ e^-$ annihilation at CESR ($\sqrt{s} \sim 10.6$~GeV) using kaons with momenta below $0.7\ \rm GeV/c$. The inclusive branching ratio into one charged kaon is $(1.60 \pm 0.12 \pm 0.19)\%$. For the exclusive decays, $B(τ\to K^-) = (0.66 \pm 0.07 \pm 0.09)\%$, $B(τ\to K^- π^0) = (0.51 \pm 0.10 \pm 0.07)\%$, and, based on three events, $B(τ\to K^- π^0 π^0) < 0.3\%$ at the 90\% confidence level. These represent significant improvements over previous results. $B(τ\to K^- π^0)$ is measur…
The problem of the $Ξ_{c}^{+}$ lifetime is considered in the framework of {\em Heavy-Quark Expansion} and $SU(3)_{flavor}$ symmetry. The lifetime of $Ξ_{c}^{+}$ is expressed in terms of measurable inclusive quantities of the other two charmed baryons belonging to the same $SU(3)_{flavor}$ multiplet in a model-independent way. In such a treatment, inclusive decay rates of singly Cabibbo suppressed decay modes have a prominent role. An analogous approach is applied to the multiplet of charmed mesons yielding interesting predictions on $D_{s}^{+}$ properties. The results obtained indicate that a …
In this work we study the $Σπ$ and $Λπ$ production off free nucleons driven by the strangeness-changing weak charged current. We calculate the total cross sections for all possible channels and estimate the flux-averaged total cross sections for experiments like MiniBooNE, SciBooNE, T2K, and Minerva. The model is based on the lowest order effective SU(3) chiral Lagrangians in the presence of an external weak charged current and contains Born and the lowest-lying decuplet resonant mechanisms that can contribute to these reaction channels. We also compare and discuss our results with others foll…
We study singly Cabibbo-suppressed two-body hadronic decays of the charmed baryon $Λ_c^+$, namely, $Λ_c^+\to ΛK^+, pπ^0, pη, nπ^+,Σ^0K^+,Σ^+ K^0$. We use the measured rate of $Λ_c^+\to pϕ$ to fix the effective Wilson coefficient $a_2$ for naive color-suppressed modes and the effective number of color $N_c^{\rm eff}$. We rely on the current-algebra approach to evaluate $W$-exchange and nonfactorizable internal $W$-emission amplitudes, that is, the commutator terms for the $S$-wave and the pole terms for the $P$-wave. Our prediction for $Λ_c^+\to pη$ is in excellent agreement with the BESIII mea…
The measurement of CP-violating asymmetries and branching ratios of $B \to DK$ modes allows a theoretically-clean extraction of the CKM angle $γ$. We report recent CDF measurements with Cabibbo suppressed ($ππ$, $KK$) or doubly Cabibbo suppressed ($K^+ π^-$) $D$ decays. These measurements are performed for the first time in hadron collisions.
We investigate a possible background of the type Omega_c^0 --> Xi_c^+ pi^- to the CLEO Xi_c^+ lifetime measurement. This decay mode may lead to an overestimate of the Xi_c^+ decay length and, therefore, increase the measured Xi_c^+ lifetime. The branching ratio Gamma(Omega_c^0 --> Xi_c^+ pi^-)/Gamma(Omega_c^0 --> Omega^- pi^+) is analyzed in the framework of the pole model and the modified current algebra. We find that the Omega_c^0 --> Xi_c^+ pi^- decay mode could not generate a substantial systematic error in the Xi_c^+ lifetime measurement. Also, it cannot significantly reduce the disagreem…
A U-spin relation among four ratios of amplitudes for $D^0 \to π^+K^-$, $K^+π^-$, $K^+K^-, π^+π^-$, including first, second and third order U-spin breaking, has been derived recently with a precision of $10^{-3}$. We study effects of new $|ΔC|=1$ operators on this relation. We find that it is not affected by U-spin scalar operators, including QCD penguin and chromomagnetic dipole operators occurring in supersymmetric and extra-dimensional models. The relation is modified by new $U=1$ operators with a sensitivity of a few percent characteristic of second order U-spin breaking. Combining this re…
We present an analysis of the m_s^2-corrections to Cabibbo-suppressed tau lepton decays employing contour improved resummation within an effective scheme which is an essential new feature as compared to previous analyses. The whole perturbative QCD dynamics of the tau-system is described by the beta-function of the effective coupling constant and by two gamma-functions for the effective mass parameters of the strange quark in different spin channels. We analyze the stability of our results with regard to high-order terms in the perturbative expansion of the renormalization group functions. A n…
Using 281 pb^-1 of data collected with the CLEO-c detector, we present new measurements of Cabibbo-suppressed decays of D0 and D+ mesons to eta and eta' final states. We make first observations of D0-->eta'pi0, eta eta, eta eta', and eta pi+ pi-, and find evidence for D+ --> eta pi+ pi0$, D+ --> eta' pi+ pi0 and D0 --> eta' pi+ pi-. We also report on improved measurements of D0-->eta pi0, D+ --> eta pi+ and D+ --> etap' pi+. Using the measured two-body Cabibbo-suppressed decays, we extract amplitudes for specific flavor topologies and compare them to those from Cabibbo-favored decays.
Using 4.8 fb$^{-1}$ of data taken with the CLEO II detector, the branching fraction for the Cabibbo-suppressed decay $D^+\toπ^0\ell^+ν$ measured relative to the Cabibbo favored decay $D^+\to\bar{K^0}\ell^+ν$ is found to be $0.046\pm 0.014\pm 0.017$. Using $V_{cs}$ and $V_{cd}$ from unitarity constraints, we determine $| f_+^π(0)/f_+^K(0)|^2=0.9\pm 0.3\pm 0.3$ We also present a 90% confidence level upper limit for the branching ratio of the decay $D^+ \to ηe^+ν_e$ relative to that for $D^+ \to π^0 e^+ν_e$ of 1.5.
We measure the branching fraction for the Singly Cabibbo-suppressed decay $D^0\rightarrow K^0_S\,K^0_S\,π^+π^-$, and we search for $CP$ violation via a measurement of the $CP$ asymmetry $A^{}_{CP}$ and also the $T$-odd triple-product asymmetry $a_{CP}^{T}$. The later two measurements are complementary. We use 922~fb$^{-1}$ of data recorded by the Belle experiment, which ran at the KEKB asymmetric-energy $e^+ e^-$ collider. The branching fraction is measured relative to the Cabibbo-favored normalization channel $D^0\rightarrow K^0_S\,π^+π^-$. Singly Cabibbo-suppressed charm decays are expected …
Doubly Cabibbo-suppressed (DCS) nonleptonic weak decays of antitriplet charmed baryons are studied systematically in this work. The factorizable and nonfactorizable contributions can be classified explicitly in the topological-diagram approach and treated separately. In particular, the evaluation of nonfactorizable terms is based on the pole model in conjunction with current algebra. All three types of relevant non-perturbative parameters contributing factorizable and nonfactorizable terms are estimated in the MIT bag model. Branching fractions of all the DCS decays are predicted to be of orde…
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…
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.
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.
We report the first observation of the doubly Cabibbo-suppressed decays $D^+ \rightarrow K^+ η^{(\prime)}$ using a 791 fb$^{-1}$ data sample collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The ratio of the branching fractions of doubly Cabibbo-suppressed relative to singly Cabibbo-suppressed $D^+ \rightarrow π^+ η^{(\prime)}$ decays are $\mathcal{B}(D^+ \rightarrow K^+ η)/\mathcal{B}(D^+ \rightarrow π^+ η)$ = (3.06 $\pm$ 0.43 $\pm$ 0.14)% and $\mathcal{B}(D^+ \rightarrow K^+ η')/\mathcal{B}(D^+ \rightarrow π^+ η')$ = (3.77 $\pm$ 0.39 $\pm$ 0.10)%. From these,…
Using data collected near the Ds*+ Ds- peak production energy Ecm = 4170 MeV by the CLEO-c detector, we study the decays of Ds+ mesons to two pseudoscalar mesons. We report on searches for the singly-Cabibbo-suppressed Ds+ decay modes K+ eta, K+ eta', pi+ K0S, K+ pi0, and the isospin-forbidden decay mode Ds+ to pi+ pi0. We normalize with respect to the Cabibbo-favored Ds+ modes pi+ eta, pi+ eta', and K+ K0S, and obtain ratios of branching fractions: Ds+ to K+ eta / Ds+ to pi+ eta = (8.9 +- 1.5 +- 0.4)%, Ds+ to K+ eta' / Ds+ to pi+ eta' = (4.2 +- 1.3 +- 0.3)%, Ds+ to pi+ K0S / Ds+ to K+ K0S = (…
We present the first clear observation of the doubly Cabibbo suppressed decay D+ --> K-K+K+ and the first observation of the singly Cabibbo suppressed decay Ds+ --> K-K+K+. These signals have been obtained by analyzing the high statistics sample of photoproduced charm particles of the FOCUS(E831) experiment at Fermilab. We measure the following relative branching ratios: Gamma(D+ --> K-K+K+)/Gamma(D+ --> K-pi+pi+) = (9.49 +/- 2.17(statistical) +/- 0.22(systematic))x10^-4 and Gamma(Ds+ --> K-K+K+)/Gamma(Ds+ --> K-K+pi+) = (8.95 +/- 2.12(statistical) +2.24(syst.) -2.31(syst.))x10^-3.
Motivated by some new experimental data, we carry out a phenomenological analysis of D --> K pi decays including both Cabibbo favored and doubly Cabibbo suppressed modes. Two asymmetries, R(D^0) and R(D+), which are generated through interference between Cabbibo favored and doubly Cabibbo suppressed D --> K pi transitions, are predicted. The relative strong phase, delta_{K pi}, between D^0 --> K- pi+ and D^0 --> K+ pi- decays, is estimated. The theoretical results agree well with the current measurements.
A very precise determination of V_us can be obtained from the semi-inclusive hadronic decay width of the tau lepton into final states with strangeness. The ratio of the Cabibbo-suppressed and Cabibbo-allowed tau decay widths directly measures (V_us/V_ud)^2, up to very small SU(3)-breaking corrections which can be theoretically estimated with the needed accuracy. Together with previous LEP and CLEO data, the recent measurements by Babar and Belle of some Cabibbo-suppressed tau decays imply V_us= 0.2165 +- 0.0026_exp +- 0.0005_th, which is already competitive with the standard extraction from K_…
We report the first observation of the doubly Cabibbo-suppressed decay, $D^{+}_{s} \to K^{+}K^{+}π^{-}$ and the significantly improved measurement of the doubly Cabibbo-suppressed decay, $D^{+} \to K^{+}π^{+}π^{-}$ using $\textrm{605 fb}^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The branching ratio with respect to its Cabibbo-favored counterpart are $\mathcal{B}(D^{+}_{s} \to K^{+}K^{+}π^{-})/\mathcal{B}(D^{+}_{s} \to K^{+}K^{-}π^{+}) = 0.229\pm0.028\pm0.012)%$ and $\mathcal{B}(D^{+} \to K^{+}π^{+}π^{-})/\mathcal{B}(D^{+} \to K^{-}π^{+…
We have searched for CP violation of charmed mesons in the decays $D\to K^0_S P$, where $D$ denotes $D^0$ and $D^+_{(s)}$, and $P$ denotes the pseudo-scalar mesons $π^+$, $K^+$, $π^0$, $η$, and $η'$. No evidence of CP violation in these decays is observed. We also have measured the CP asymmetry difference between the Cabibbo suppressed decay $D^+\toϕπ^+$ and the Cabibbo favored $D^+_s\toϕπ^+$ decays in the region of $|M(K^+K^-)-M^ϕ_{PDG}|<$16 MeV/$c^2$. The measured asymmetry is corrected for the residual asymmetry due to detector effects, and the contributions of both CP and forward-backward …
We present measurements of the branching fractions for the singly Cabibbo-suppressed decays $D^+\to K^{+}K^{-}π^{+}π^{0}$ and $D_s^{+}\to K^{+}π^{-}π^{+}π^{0}$, and the doubly Cabibbo-suppressed decay $D^{+}\to K^{+}π^{-}π^{+}π^{0}$, based on 980 ${\rm fb}^{-1}$ of data recorded by the Belle experiment at the KEKB $e^{+}e^{-}$ collider. We measure these modes relative to the Cabibbo-favored modes $D^{+}\to K^{-}π^{+}π^{+}π^{0}$ and $D_s^{+}\to K^{+}K^{-}π^{+}π^{0}$. Our results for the ratios of branching fractions are $B(D^{+}\to K^{+}K^{-}π^{+}π^{0})/B(D^{+}\to K^{-}π^{+}π^{+}π^{0}) = (11.32…
We review genetic programming principles, their application to FOCUS data samples, and use the method to study the doubly Cabibbo suppressed decay D+ -> K+ pi+ pi- relative to its Cabibbo favored counterpart, D+ -> K- pi+ pi+. We find that this technique is able to improve upon more traditional analysis methods. To our knowledge, this is the first application of the genetic programming technique to High Energy Physics data.
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…
Using 232 fb-1 of e+e- collision data recorded by the BaBar experiment, we measure the ratios of three-body Cabibbo-suppressed decay rates of the D^0 meson relative to that of the Cabibbo-favored decay: B(D0 --> pi- pi+ pi0)/ B(D0 --> K- pi+ pi0) = (10.59 +/- 0.06 +/- 0.13).10^{-2} and B(D0 --> K- K+ pi0)/ B(D0 --> K- pi+ pi0) = (2.37 +/- 0.03 +/- 0.04). 10^{-2}, where the errors are statistical and systematic respectively. The precisions of these measurements are significantly better than those of the current world average values.We note that the second result differs significantly from the c…
