A search is presented for the decay Y(1S) -> gamma A0, A0 -> cc-bar, where A0 is a candidate for the CP-odd Higgs boson of the next-to-minimal supersymmetric standard model. The search is based on data collected with the BABAR detector at the Y(2S) resonance. A sample of Y(1S) mesons is selected via the decay Y(2S) -> pi+pi-Y(1S). The A0 -> cc-bar decay is identified through the reconstruction of hadronic D0, D+, and D*(2010)+ meson decays. No significant signal is observed. The measured 90% confidence-level upper limits on the product branching fraction B(Y(1S) -> gamma A0) x B(A0 -> cc-bar) range from 7.4 x 10^-5 to 2.4 x 10^-3 for A0 masses from 4.00 to 8.95 GeV/c^2 and 9.10 to 9.25 GeV/c^2, where the region between 8.95 and 9.10 GeV/c^2 is excluded because of background from Y(2S) -> gamma chi_bJ(1P), chi_bJ(1P) -> gamma Y(1S) decays.
The study of the process $e^+e^- \to W^+W^-$ at Linear Collider energies presents a good opportunity to investigate anomalous triple gauge boson couplings and $W^+_LW^-_L$ rescattering. The helicity analysis of the $e^+e^- \to W^+_LW^-_L$ decays will benefit if the charm quark containing jet can be identified for events which contain one hadronic $W$ boson decay to a charm and another quark. A JAVA implementation of the SLD collaboration's topological vertex finding algorithm (ZVTOP) in the linear collider analysis framework has been used to extract charm tag efficiencies and purities based on…
We report a new measurement of A_c using data obtained by SLD in 1993-98. This measurement uses a vertex tag technique, where the selection of a c hemisphere is based on the reconstructed mass of the charm hadron decay vertex. The method uses the 3D vertexing capabilities of SLD's CCD vertex detector and the small and stable SLC beams to obtain a high c-event tagging efficiency and purity of 28% and 82%, respectively. Charged kaons identified by the CRID detector and the charge of the reconstructed vertex provide an efficient quark-antiquark tag, with the analyzing power calibrated from the da…
We have measured, with electron tagging, the forward-backward asymmetries of charm- and bottom-quark pair productions at $<\sqrt{s} >$=58.01GeV, based on 23,783 hadronic events selected from a data sample of 197pb$^{-1}$ taken with the TOPAZ detector at TRISTAN. The measured forward-backward asymmetries are $A_{FB}^c = -0.49 \pm 0.20(stat.) \pm 0.08 (sys.)$ and $A_{FB}^b = -0.64 \pm 0.35(stat.) \pm 0.13 (sys.)$, which are consistent with the standard model predictions.
Using 230.2 fb^(-1) of e+e- annihilation data collected with the BABAR detector at and near the peak of the Y(4S) resonance, 489 +/- 55 events containing the pure leptonic decay D_s^+ --> mu^+ nu_mu have been isolated in charm-tagged events. The ratio of partial widths Gamma(D_s^+ --> mu^+ nu_mu)/Gamma(D_s^+ --> phi pi^+) is measured to be 0.143 +/- 0.018 +/- 0.006 allowing a determination of the pseudoscalar decay constant f_{D_s} = (283 +/- 17 +/- 7 +/- 14) MeV. The errors are statistical, systematic, and from the D_s^+ --> phi pi^+ branching ratio, respectively.
The analysis of quantum-correlated $D-\bar{D}$ decays produced at the $ψ(3770)$ resonance gives unique insight into quantities such as strong-phase differences and coherence factors. Knowledge of these parameters is invaluable for measurements of the CKM-angle $γ$ ($ϕ_3$) in $B \to DK$ decays. Results from CLEO-c analyses performed at the $ψ(3770)$ resonance in a variety of decay channels are reported, and their consequences for the determination of $γ$ is assessed. Future prospects are given for extensions to the present studies.
Precision determination of the CKM angle $γ/ϕ_3$ depends upon constraints on charm mixing amplitudes, measurements of doubly-Cabibbo suppressed amplitudes and relative phases, and studies of charm Dalitz plots tagged by flavor or CP eigenstates. In this note we describe the technique used at CLEO-c to constrain the $K_{S,L}ππ$ model uncertainty, and its impact on $γ/ϕ_3$ measurements at B-factories presented at the Charm 2007 Workshop.
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 introduce a method to discover the Higgs boson at the Large Hadron Collider (LHC) through its decay to W^+W^-, where one boson decays to leptons, and the other decays to c+jet. This mechanism is complementary to the decay into dileptons, but has the potential to measure the invariant mass peak of the Higgs boson, and to avoid large recently discovered QCD backgrounds from heavy flavor decays. In addition, this mechanism motivates the study and creation of a dedicated charm jet tagger at LHC experiments. Existing charm jet tagging, in the form of fakes to bottom jet tagging, provides sensiti…
We report on a study of inclusive $B^-$ and $\bar{B}^0$ meson decays to ${D^0 X}$, ${\bar{D}^0 X}$, ${D^+ X}$, ${D^- X}$, ${D_s^+ X}$, ${D_s^- X}$, ${Λ_c^+ X}$, ${\barΛ_c^- X}$, based on a sample of 231 million $B\bar{B}$ events recorded with the BABAR detector at the $Υ{(4S)}$ resonance. Events are selected by completely reconstructing one $B$ and searching for a reconstructed charm particle in the rest of the event. From the measured branching fractions of these decays, we infer the number of charm and anti-charm particles per $\bar{B}$ decay, separately for charged and neutral parents. We d…
We report on the inclusive branching fractions of $B^-$ and of ${\bar B}^0$ mesons decaying to ${D^0 X}$, ${{\bar D}^0 X}$, ${D^+ X}$, ${D^- X}$, ${D_s^+ X}$, ${D_s^- X}$, ${Λ_c^+ X}$, ${{\bar Λ}_c^- X}$, based on a sample of 88.9 million $B \bar B$ events recorded with the $BABAR$ detector at the $Υ(4S)$ resonance. Events are selected by completely reconstructing one $B$ and searching for a reconstructed charmed particle in the rest of the event. We measure the number of charmed and of anti-charmed particles per $B$ decay and derive the total charm yield per $B^-$ decay, $n_c^- = 1.313 \pm 0.…
Several different vertex detector designs for the Linear Collider Detector(LCD) are evaluated in the context of measurements of the branching ratio of the standard model Higgs particle decaying into charm/anti-charm final states. Fast Monte Carlo simulations are used to model the detector and neural network-optimized flavor tagging is used to perform the measurements. These tools are used to study the effects of pixel resolution, material thickness, and inner layer radius on the flavor tagging efficiency-purity curve and ultimately on the branching ratio measurement error.
Using samples of 102 million $Υ(1S)$ and 158 million $Υ(2S)$ event samples collected with the Belle detector, we report on the first search for charge-parity-even charmonium and charmonium-like states in $Υ(1S)$ and $Υ(2S)$ radiative decays. No significant $χ_{cJ}$ or $η_c$ signal is observed and 90% C.L. limits on $\BR(Υ(nS)\to γχ_{cJ})$ ($n=1,2$ and $J=1,2,3$) are obtained. No significant signal of any charmonium-like state is observed. The product branching fraction limits $\BR(Υ(nS)\to γX(3872))$ $\BR(X(3872)\toπ^+π^-\jpsi)$, $\BR(Υ(nS)\to γX(3872))$ $\BR(X(3872)\toπ^+π^-π^0 \jpsi)$, $\BR(…
We report a search for non-Standard Model physics through the measurement of CP-violating asymmetry in the Cabibbo suppressed D0->pi+pi- and D0->K+K- decays reconstructed in about 5.94/fb of CDF data. We use the strong D*+->D0pi+ decay ("D* tag") to identify the flavor of the charmed meson at production time and exploit CP-conserving strong c-cbar pair-production in p-pbar collisions. Large samples of Cabibbo favored D0->K-pi+ decays with and without D* tag are used to highly suppress systematic uncertainties due to detector effects. The results are the world's most precise measurements to dat…
We present a preliminary measurement of the inclusive charmless semileptonic branching fraction of the B meson, based on $140 fb^{-1}$ of data collected by the Belle detector at the KEKB $e^+e^-$ asymmetric collider. Events are tagged by fully reconstructing one of the B mesons, produced in pairs from $Υ(4S)$. The signal for $b \to u$ semileptonic decay is distinguished from the $b \to c$ semileptonic background using the hadronic and leptonic invariant mass distributions $M_X$ and $q^2$. We find the partial branching fraction for the kinematical region given by $M_X < 1.7 GeV/c^2$ and $q^2>8 …
Using a sample of 158 million Υ(2S) events collected with the Belle detector, charmonium and charmonium-like states with even charge parity are searched for in Υ(2S) radiative decays. No significant χ_{cJ} or η_c signal is observed and the following upper limits at 90% confidence level (C.L.) are obtained: BR(Υ(2S)\to γχ_{c0})< 1.0 \times 10^{-4}, BR(Υ(2S) \to γχ_{c1})<3.6 \times 10^{-6}, BR(Υ(2S) \to γχ_{c2})<1.5 \times 10^{-5}, and BR(Υ(2S) \to γη_c)< 2.7 \times 10^{-5}. No significant signal of any charmonium-like state is observed, and we obtain the limits \BR(Υ(2S)\to γX(3872))\times\BR(X…
A brief review of experimental results on charmonium and charmonium-like hadron spectroscopy at B-factories is presented. A special focus is put on recent results of eta_c and eta_c(2S) study, X(3872) radiative decays, omega J/psi final state study and search for charmonium production in radiative Upsilon decays.
We present a measurement of the Cabibbo-Kobayashi-Maskawa matrix element |V_ub|, based on 253 fb^-1 of data collected by the Belle detector at the KEKB e^+e^- asymmetric collider. Events are tagged by fully reconstructing one of the B mesons, produced in pairs from Upsilon(4S). The signal for b->u semileptonic decay is distinguished from the b->c background using the hadronic mass M_X, the leptonic invariant mass squared q^2 and the variable P_+ = E_X-|\vec{p}_X|. The results are obtained for events with the prompt-lepton momentum, p_l^* >= 1GeV/c, in three kinematic regions (1) M_X < 1.7 Gev/…
Search for supersymmetry in final states with missing transverse momentum and charm-tagged jets using 139 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}=$ 13 TeV with the ATLAS detector
Using 24 million $ψ' \equiv ψ(2S)$ decays in CLEO-c, we have searched for higher multipole admixtures in electric-dipole-dominated radiative transitions in charmonia. We find good agreement between our data and theoretical predictions for magnetic quadrupole (M2) amplitudes in the transitions $ψ' \to γχ_{c1,2}$ and $χ_{c1,2} \to γJ/ψ$, in striking contrast to some previous measurements. Let $b_2^J$ and $a_2^J$ denote the normalized M2 amplitudes in the respective aforementioned decays, where the superscript $J$ refers to the angular momentum of the $χ_{cJ}$. By performing unbinned maximum like…
Based on the data samples collected at the energies of $J/ψ$, $ψ(3686)$, $ψ(3770)$ and $ψ(4040)$ resonances with the BESIII detector at the BEPCII storage ring, we present charmonium decays in two aspects. One is the search for baryonic decays of $ψ(3770)$ and $ψ(4040)$, including $Λ\barΛπ^+π^-$, $Λ\barΛπ^0$, $Λ\barΛη$, $Σ^+ \barΣ^-$, $Σ^0 \barΣ^0$, $Ξ^-\barΞ^+$ and $Ξ^0\barΞ^0$. None are observed, and upper limits are set at the 90% confidence level. The other is the light hadron spectroscopy from charmonium radiative decays, including the spin-parity analysis of the $p\bar p$ mass-threshold …
Recent results in studies of bottomonium especially relevant to charmonium are reviewed. This report covers dipion transition matrix elements, $η$ production in $Υ$ transitions, $Υ$ decays to invisible particles, a search for a non-standard-model pseudoscalar Higgs in $Υ$ radiative decays, and $Υ$ radiative decays to $\rm{f_2(1270)}$, $η$, and $η'$.
We have searched for $D^0 - \bar{D}^0$ mixing in $D^{*+} \to π^+ D^0$ decays with $D^0 \to K^{(*)} e ν$ in a sample of $e^+ e^- \to {c\bar c}$ events produced near 10.58 GeV. The charge of the slow pion from charged $D^*$ decay tags the charm flavor at production, and it is required to be consistent with the flavor of a fully reconstructed second charm decay in the same event. We observe 3 mixed candidates compared to 2.85 background events expected from simulation. We ascribe a 50% systematic uncertainty to this expected background rate. We find a central value for the mixing rate of $0.4 \ti…
The rate of secondary charm-quark-pair production has been measured in 4.4 million hadronic Z0 decays collected by OPAL. By selecting events with three jets and tagging charmed hadrons in the gluon jet candidate using leptons and charged D* mesons, the average number of secondary charm-quark pairs per hadronic event is found to be (3.20+-0.21+-0.38)x10-2.
Using an inclusive method, BR(b -> D\bar{D}X) has been measured in hadronic Z^0 decays with the OPAL detector at LEP. The impact parameter significance of tracks opposite tagged b-jets is used to differentiate b -> D\bar{D}X decays from other decays. Using this result, the average number of charm and anti-charm quarks produced per beauty quark decay, n_c, is determined.
We report a measurement of the branching fraction of the exclusive charmless semileptonic decay B+ --> omega l+ nu, where l is either an electron or a muon. We use samples of B+ mesons tagged by a reconstructed charmed semileptonic decay of the other B meson in the event. The measurement is based on a dataset of 426.1 fb-1 of e+e- collisions at a center-of-mass energy of 10.58 GeV recorded with the BABAR detector at the PEP-II asymmetric-energy e+e- storage rings. We measure a branching fraction of BF(B+ --> omega l+ nu) = (1.35 +/- 0.21 +/- 0.11) x 10(-4), where the uncertainties are statisti…
Recent experimental bounds on rare charm decays offer a chance to improve our theoretical understanding of physics present in $c \to u γ$ and $c \to u l^+ l^-$ transitions. Standard Model and New Physics contributions are reviewed for inclusive and exclusive $D \to Vγ$, $D^+ \to π^+ l^+ l^-$, $D \to l^+ l^-$ decays. Observables important for search of New Physics are discussed. Possibility to observe CP violation in rare charm decays is questioned.
We have measured the probability, n(g->cc~), of a gluon splitting into a charm-quark pair using 1.7 million hadronic Z decays collected by the L3 detector. Two independent methods have been applied to events with a three-jet topology. One method relies on tagging charmed hadrons by identifying a lepton in the lowest energy jet. The other method uses a neural network based on global event shape parameters. Combining both methods, we measure n(g->cc~)= [2.45 +/- 0.29 +/- 0.53]%.
We report a preliminary study of the branching fractions and $q^2$ distributions of exclusive charmless semileptonic B decays, using events tagged by fully reconstructing one of the $B$ mesons in a hadronic decay mode. These results are obtained from a data sample that contains 535 $\times 10^6\ B\bar{B}$ pairs, collected near the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^+ e^-$ collider.
In this work, we investigate the decay widths and the line shapes of the open-charm radiative and pionic decays of Y(4274) with the $D_s\bar{D}_{s0}(2317)$ molecular charmonium assignment. Our calculation indicates that the decay widths of $Y(4274)\to D^{+}_{s}D^{*-}_{s}γ$ and $Y(4274)\to D^+_{s}D^-_{s}π^0$ can reach up to 0.05 keV and 0.75 keV, respectively. In addition, the result of the line shape of the photon spectrum of $Y(4274)\to D_s^+ {D}_s^{*-} γ$ shows that there exists a very sharp peak near the large end point of photon energy. The line shape of the pion spectrum of $Y(4274)\to D_…
We present a measurement of the branching fractions for the Cabibbo-favored radiative decay, $D^{0} \to {\bar K}^{*0} γ$, and the Cabibbo-suppressed radiative decay, $D^{0} \to ϕγ$. These measurements are based on a data sample corresponding to an integrated luminosity of $387.1 fb^{-1}$, recorded with the BaBar detector at the PEP-II $e^+e^-$ asymmetric-energy collider operating at center-of-mass energies 10.58 and 10.54 GeV. We measure the branching fractions relative to the well-studied decay $D^{0} \to K^{-} π^{+}$ and find ${\cal B}(D^{0} \to {\bar K}^{*0} γ)/{\cal B}(D^{0} \to K^{-} π^{+…
Motivated by very recent measurement of the radiative decays of $Υ(1S)$ to $χ_{c1}$ at Belle, we use the nonrelativistic QCD factorization theory and calculate the branching fractions of the radiative decays of bottomonium into S-wave and P-wave charmonium, i.e. $Υ(nS) \to η_c(nS)+γ$ and $Υ(nS)\to χ_{cJ}+γ$. We systematically studied the branching fractions of the radiative decays of bottomonium into charmonium. Compared to the previous calculation, we obtained the analytical expression for the decay widths and considered the color-octet contributions. For $Υ(nS) \to η_c(nS)+γ$, the relativist…
This review briefly outlines recent experimental results from the charmonium system. These include new measurements of the M1 radiative transition rates $B(ψ(1S,2S)\toγη_c(1S))$; new insights into the mass of the $η_c(1S)$; the observation of $J/ψ(1S)$ decays to three photons; new measurements of the two-photon widths of the $χ_{cJ}(1P)$; the observation of radiative decays of the $χ_{cj}(1P)$ to light quarks; a precise measurement of the $h_c(1P)$ mass; and an update on properties of the $η_c(2S)$. Each result adds piecemeal to our understanding of the strong force.
Knowing the mass of the b-quark is essential to the study of the structure and decays of B mesons as well as to future tests of the Higgs mechanism of mass generation. We present recent preliminary measurements of the b-quark mass and related nonperturbative parameters from moments of kinematic distributions in charmed and charmless semileptonic and radiative penguin B decays. Their determination from charmless semileptonic B decays is the first measurement in this mode. The data were collected by the BABAR detector at the PEP-II asymmetric-energy e+e- -collider at the Stanford Linear Accelera…
We discuss the possibilities of producing the X(3872), which is assumed to be a D \bar D^* bound state, in radiative decays of charmonia. We argue that the ideal energy regions to observe the X(3872) associated with a photon in e^+e^- annihilations are around the Y(4260) mass and around 4.45 GeV, due to the presence of the S-wave D \bar D_1(2420) and D^* \bar D_1(2420) threshold, respectively. Especially, if the Y(4260) is dominantly a D \bar D_1 molecule and the X(3872) a D \bar D^* molecule, the radiative transition strength will be quite large.
We construct a CP-violating observable which does not require flavor or CP tagging of the initial state. The proposed decay asymmetry could be measured at both threshold and non-threshold charm physics experiments and provide better sensitivity to small CP-violating parameters in charm decays.
We review current experimental results on charm mixing and CP violation. We survey experimental techniques, including time-dependent, time-independent, and quantum-correlated measurements. We review techniques that use a slow pion tag from D*+ --> pi+ D0 + c.c. decays and those that do not, and cover two-body and multi-body D0 decay modes. We provide a summary of D-mixing results to date and comment on future experimental prospects at the LHC and other new or planned facilities.
Using a sample of 102 million $Υ(1S)$ events collected with the Belle detector, we report on the first search for charge-parity-even charmonium and charmonium-like states in $Υ(1S)$ radiative decays. No significant $χ_{cJ}$ or $η_c$ signal is observed and 90% C.L. limits on $\BR(Υ(1S)\to γχ_{c0})<6.5 \times 10^{-4}$, $\BR(Υ(1S)\to γχ_{c1})<2.3\times 10^{-5}$, $\BR(Υ(1S)\to γχ_{c2})<7.6 \times 10^{-6}$, and $\BR(Υ(1S)\to γη_c)<5.7\times 10^{-5}$ are obtained. The product branching fraction limits $\BR(Υ(1S)\to γX(3872)) \BR(X(3872)\toπ^+π^-\jpsi)< 1.6 \times 10^{-6}$, $\BR(Υ(1S)\to γX(3872)) \B…
We study the $Z^\pm(4430)$ meson within a heavy hadron molecule interpretation where the $Z$ is considered as a bound state of a vector $D^\ast(2010)$ and an axial-vector $D_1(2420)$. We give predictions for the strong hidden-charm $Z^\pm(4430) \to π^\pm ψ$ and $π^\pmψ^\prime$ decay widths and also study the radiative $Z^\pm\;(J^P=1^-) \to π^\pmγ$ decay properties in a phenomenological Lagrangian approach. Our findings are qualitatively in line with the experimental observation that the $π^\pmψ^\prime$ transition dominates over the $π^\pmψ$ decay mode despite a smaller phase space. The width f…
Spectroscopy results for Belle and BaBar are reported. A particular focus is put on new results of the X(3872) state with its radiative decays to $J$/$ψ$$γ$ and $ψ'$$γ$, its decay into $J$/$ψ$3$π$ and the search for production in radiative Upsilon decays. Another focus is $L$=2 mesons, in particlar a possible $D$-wave assignment to the X(3872) and the confirmation of an Upsilon $D$-wave state.
Coupled-channel effects due to coupling of charmonia to the charmed and anticharmed mesons are of current interest in heavy quarkonium physics. However, the effects have not been unambiguously established. In this paper, a clean method is proposed in order to examine the coupled-channel effects in charmonium transitions. We show that the hindered M1 radiative transitions from the 2P to 1P charmonia are suitable for this purpose. We suggest to measure one or more of the ratios Gamma(h_c'-->chi_{cJ} gamma)/Gamma(chi_{cJ}'-->chi_{cJ} pi^0) and Gamma(chi_{cJ}'-->h_c gamma)/Gamma(chi_{cJ}'-->chi_{c…
The production of charm jets in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=7$ TeV was measured with the ALICE detector at the CERN Large Hadron Collider. The measurement is based on a data sample corresponding to a total integrated luminosity of $6.23$ ${\rm nb}^{-1}$, collected using a minimum-bias trigger. Charm jets are identified by the presence of a D$^0$ meson among their constituents. The D$^0$ mesons are reconstructed from their hadronic decay D$^0\rightarrow$K$^{-}π^{+}$. The D$^0$-meson tagged jets are reconstructed using tracks of charged particles (track-based…
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
We present the prospects for studying quantum correlated charm decays at the ψ(3770) using 0.5--1.0 ab^{-1} of data at SuperB. The impact of studying such double tagged decays upon measurements in other charm environments will be discussed.
Quantum correlations in $ψ(3770) \to D^0\bar{D}^0$ provide unique access to information about strong phase differences. Precision determination of the CKM phase $γ/ϕ_3$ via $B \to D K$ decays depends upon constraints on charm mixing amplitudes, measurements of doubly-Cabibbo suppressed amplitudes and relative phases, and studies of correlated charmed meson decays tagged by flavor or CP eigenstates. CP-tagged $D^0 \to K^-π^+π^-π^+$ decays and CP-tagged $D^0 \to K^0_Sπ^+π^-$ Dalitz plots are only available at CLEO-c. Using the 818 pb$^{-1}$ CLEO-c data sample produced by the Cornell Electron Sto…
The experimental program of the Seventh International Workshop on Charm Physics (CHARM 2015) is summarized. Highlights of the workshop include results from heavy flavor production, quarkonium and exotic states, hadronic decays and Dalitz analyses, semileptonic and leptonic decays, rare and radiative decays, charm mixing, and CP and T violation.
$B^0_d$-$\bar{B}{}^0_d$ oscillations are observed in ``self-tagged'' samples of partially reconstructed $B$ mesons decaying into a lepton and a charmed meson collected in $p\bar p$ collisions at $\sqrt{s} = 1.8$ TeV. A flavor tagging technique is employed which relies upon the correlation between the flavor of $B$ mesons and the charge of nearby particles. We measure the flavor oscillation frequency to be $Δm_d = 0.471 ^{+0.078}_{-0.068} \pm 0.034 ps^{-1}$. The tagging method is also demonstrated in exclusive samples of $B^+_u \to J/ψK^+$ and $B^0_d \to J/ψK^{*0}(892)$, where similar flavor-ch…
Belle II is a major upgrade of the Belle experiment and will operate at the $B$-factory SuperKEKB in Japan. Here we discuss the expected sensitivity of Belle II for $D^0 - \bar{D}^0$ mixing and $CP$ violation measurements in the charm sector, which will benefit from a factor 50 increase in statistics and an improved vertex detection and particle identification. The impact on the determination of CKM parameters from the measurements of purely leptonic $D$ mesons decays is discussed. Finally a novel method of flavour tagging to substantially increase the sample of $D^0$ and $\bar{D}^0$ is presen…
A search for charge-parity (CP) violation in $D^0 \to K^- K^+$ and $D^0 \to π^-π^+$ decays is reported, using $pp$ collision data corresponding to an integrated luminosity of 5.9 $\mathrm{fb}^{-1}$ collected at a center-of-mass energy of 13 TeV with the LHCb detector. The flavor of the $D^0$ meson is determined from the charge of the pion in $D^*(2010)^+ \to D^0 π^+$ decays or from the charge of the muon in $\kern 0.18em\overline{\kern -0.18em B}{} \to D^0 μ^- \barν_μX$ decays. The difference between the CP asymmetries in $D^0 \to K^- K^+$ and $D^0 \to π^-π^+$ decays is measured to be $ΔA_{\rm…
We report a preliminary branching fraction of (1.80 +/- 0.37(stat.) +/- 0.23(syst.)) x 10^-4 for the charmless exclusive semileptonic B+ -> pi0 l+ nu decay, where l can be either a muon or an electron. This result is based on data corresponding to an integrated luminosity of 81 fb^-1 collected at the Upsilon(4S) resonance with the BABAR detector. The analysis uses BBbar events that are tagged by a B meson reconstructed in the semileptonic B- -> D0 l- nubar (X) decays, where X can be either a gamma or a pi0 from a D* decay.
We report on recent results on charmless hadronic and radiative rare $B_s^0$ decays, based on the data collected by the Belle experiment at the KEKB $e^+e^-$ collider. These include the studies of $B_s^0\rightarrow K^0\bar{K^0}$, $B_s^0\rightarrowϕγ$ and $B_s^0\rightarrowγγ$.
Fermilab E791, a very high statistics charm particle experiment, recently completed its data taking at Fermilab's Tagged Photon Laboratory. Over 20 billion events were recorded through a loose transverse energy trigger and written to 8mm tape in the the 1991-92 fixed target run at Fermilab. This unprecedented data sample containing charm is being analysed on many-thousand MIP RISC computing farms set up at sites in the collaboration. A glimpse of the data taking and analysis effort is presented. We also show some preliminary results for common charm decay modes. Our present analysis indicates …
We present a direct measurement of the parity-violation parameter A_c. The measurement is based on 550k Z^0 decays collected by the SLD detector. The mean electron-beam polarization is |P_e| = 73 %. The tagging of c-quark events was performed using two methods: The exclusive reconstruction of D^*+, D^+, and D^0 mesons, and the inclusive P_T spectrum of soft-pions (pi_s) in the decay of D^*+ -> D^0 pi_s^+. The results of these two methods are combined to give A_c = 0.688 +- 0.035(stat.) +- 0.025(sys.) (preliminary).
The inclusive production of D*+- mesons in photon-photon collisions has been measured using the OPAL detector at LEP at e+e- centre-of-mass energies of 183 and 189GeV. The D* mesons are reconstructed in their decay to D0pi+ with the D0 observed in the two decay modes Kpi+ and Kpi+pi-pi+. After background subtraction, 100.4+-12.6(stat) D*+- mesons have been selected in events without observed scattered beam electron ("anti-tagged") and 29.8+-5.9 (stat) D*+- mesons in events where one beam electron is scattered into the detector ("single-tagged"). Direct and single-resolved events are studied se…
We study the radiative charmless $B_{(s)}\to V(A)γ$ decays in perturbative QCD (pQCD) approach to the leading order in $α_s$ (here $V$ and $A$ denotes vector mesons and two kinds of axial-vector mesons: $^3P_1$ and $^1P_1$ states, respectively.). Our predictions of branching ratios are consistent with the current available experimental data. We update all $B_{(s)}\to V$ form factors and give the predictions for $B\to A$ form factors using the recent hadronic inputs. In addition to the dominant factorizable spectator diagrams, which is form factor like, we also calculate the so-called ``power s…
