Due to an excellent mass resolution and a large amount of available data, the CDF experiment, located at the Tevatron proton-antiproton accelerator, allows the precise measurement of spectroscopic properties, like mass and decay width, of a variety of states. This was exploited to examine the first orbital excitations of the Lambdac baryon, the resonances Lambdac(2595) and Lambdac(2625), in the decay channel Lambdac+ pi+ pi-, as well as the Lambdac spin excitations Sigmac(2455) and Sigmac(2520) in its decays to Lambdac+ pi- and Lambdac+ pi+ final states in a data sample corresponding to an integrated luminosity of 5.2 invfb. We present measurements of the mass differences with respect to the Lambdac and the decay widths of these states, using significantly higher statistics than previous experiments.
We present measurements of charmonium and bottomonium production using a data sample collected by CDF during the 1992-93 p-pbar collider run at the Fermilab Tevatron.
After many upgrades to the CDF detector and to the accelerator complex, Run II began in April 2001. The new detector has improved capabilities for charm physics, and first results from the analysis of early Tevatron Run II data are reported here.
Reporting, for the CDF and D0 collaborations, results from the 1992-93 Fermilab Tevatron Collider run concerning charm and beauty quark production and beauty meson decay properties.
he CDF experiment at the Fermilab Tevatron p-pbar collider pioneered the exploration of charmless b-hadron decays in hadron collisions. This provided a unique, rich and highly successful program of measurements that is currently reaching its full maturity. I report here results on two-body decays and the new analysis of B0s-->phiphi decays in a event sample corresponding to 2.9 fb-1.
The study of the charm quark continues to have wide interest as a possible avenue for the discovery of physics beyond the Standard Model and can as well be used as a tool for understanding the non-perturbative aspects of the strong interactions. Owning to the large production cross-section available at the Tevatron collider and to the flexibility of a trigger on fully hadronic final states, the CDF experiment, in a decade of successful operations, collected millions of charmed mesons decays which can be used to investigate the details of the physics of the production and decay processes of the…
We present CDF results on the branching fractions and time-integrated direct CP asymmetries for Bd, Bs and Lb decay modes into pairs of charmless charged hadrons (pions, kaons and protons). The data-set for these measurements amounts to 1fb^{-1} of pbar-p collisions at a center of mass energy 1.96TeV. We report on the first observation of the Bs->Kpi, Lb-ppi and Lb->pK decay modes and on the measurement of their branching fractions and direct CP asymmetries.
We present new CDF results on the branching fractions and time-integrated direct CP asymmetries for $B^0$ and $B^0_s$ decay modes into pairs of charmless charged hadrons (pions or kaons). The data-set for this update amounts to 1 $\mathrm{fb}^{-1}$ of $p\bar p$ collisions at a center of mass energy 1.96 $\mathrm{TeV}$. We report the first observation of the $B_s \to K^- π^+$ mode and a measurement of its branching fraction and direct CP asymmetry. We also observe for the first time two charmless decays of the $Λ_b^0$-baryon: $Λ_b^0 \to pπ^-$ and $Λ_b^0 \to pK^-$.
Penguin transitions play a key role in the search of New Physics hints in the heavy flavor sector. During the last decade CDF has been exploring this opportunity with a rich study of two--body charmless decays of neutral B mesons into charged final--state particles. After briefly introducing the aspects of this physics peculiar to the hadron collision environment, I report on two interesting results: the first polarization measurement of the B^0_s --> phi phi decay and the update of the B^0(_s) --> h^+h'^- decays analysis.
Exploiting the full Run II data sample collected by the CDF trigger on displaced vertices, we present a search for CP violation in neutral D mesons decays to hadronic final states. We use the strong D^{*+}\to D^{0}π^{+} (and c.c.) decay to identify the flavor of the charmed meson at production time and exploit CP-conserving strong c\bar{c} pair-production in p\bar{p} collisions. The results are the world's most precise measurements to date and confirm the presence of sizable CP-violating effects in the charm sector as recently observed by the LHCb Collaboration
We report the recent evidence for a new narrow structure, Y(4140), decaying to the $J/ψϕ$ final state, in exclusive $B^+\to J/ψϕK^+$ decays in a data sample corresponding to an integrated luminosity of 2.7 \ifb collected at the CDF II detector. This narrow structure with its mass well above open charm pairs is unlikely to be a candidate for a conventional charmonium state. From a study of the X(3872) mass and width based on the world's largest sample of $X(3872)\to J/ψπ^+π^-$ decays, we find that our X(3872) signal is consistent with a single state, and leads to the most precise measurement of…
A summary of the results of several recent studies of charm mixing is presented. A number of different methods were used, including the measurement of lifetime ratios for final states of different CP, time dependence of wrong-sign hadronic decays, fits to time-dependent Dalitz plots, and searches for wrong-sign semi-leptonic decays. Taken together, they suggest mixing is of order 1%. The status of searches for indirect CP violation is also reported.
We 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…
The CDF II detector has the capability of triggering on displaced tracks. Because of this ability, CDF II has accrued large samples of charmed meson decays to fully hadronic final states in 64 pb^-1 of ppbar collision data gathered at sqrt(s) = 1.96 TeV. Using initial Run II data samples, the production cross sections for J/psi, D0, D+, D*+ and Ds+ mesons have been measured. Ratios of branching ratios for Cabibbo suppressed final states and CP asymmetries in D0 meson decays have been studied. A measurement of the mass difference m(Ds+) - m(D+) has been done, and a limit for the branching fract…
I present recent results of measurements of branching fractions and CP-violating asymmetries in B0, Bs, and Lambda_B two-body charmless decays at the upgraded Collider Detector at the Fermilab Tevatron. Measurements of rates of flavor-changing neutral current B0, Bs -->mu+mu- and B+/B0/Bs --> mu+mu- K+/K*0/phi decays are also reported. The results are extracted from samples corresponding to time-intergrated luminosities ranging from 0.78 to 1 fb-1.
First charm physics results from the CDF and D0 experiments at the Tevatron Run II are presented. With the addition of the Secondary Vertex Trigger CDF has become a competitive charm experiment.
Results for the production of charm and beauty quarks in proton anti-proton collisions at ECM=1.96 TeV (Tevatron) with the two multi purpose experiments CDF and D0 using an integrated luminosity of up to 1 fb^-1 are presented. With the data measurement of the production me chanism for charm and beauty quarks are done. These measurements are leading to a better understanding of the QCD in the transition region between pertubative a nd nonpertubative QCD. The charm-charm angular correlation is measured with D me sons at the CDF experiment. The Quarkonium production for charm and beauty final sta…
We present world-leading results on CP-violating asymmetries and branching fractions of several decay modes of B0, B0s, and Λb hadrons into charmless two-body, and of B\pm into charm, final states collected by the CDF detector. We also report a new measurement of CP-violating asymmetries in D\ast\pm-tagged D0 \rightarrow h+h- (h = K or π) decays, where any enhancement from the Standard Model prediction would be unambiguous evidence for New Physics.
We present the latest results on the search of bottom baryon states Sigma_b using 1 fb^-1 of CDF data. The study is performed with the world's largest sample of fully reconstructed Lambda_b decays collected by CDF II detector at the collision energy of 1.96 TeV in the hadronic trigger path. We observe 4 new states consistent with Sigma_b(*)+/- bottom baryons.
We report on the observation of $D^0$--$\bar{D}^0$ oscillations by measuring the time-dependent ratio of yields for the rare decay $D^0 \rightarrow K^+π^-$ to the favored decay $D^0 \rightarrow K^-π^+$ at the Collider Detector at Fermilab (CDF). Using 9.6 fb$^{-1}$ of integrated luminosity of $\sqrt{s}$ = 1.96 TeV $p$$\bar{p}$ collisions recorded in the full CDF Run II, the signals of $7.6 \times 10^6$ $D^0\rightarrow K^-π^+$ and $33 \times 10^3$ $D^0\rightarrow K^+π^-$ decays are reconstructed in $D^{*}$-tagged events, with proper decay times between 0.75 and 10 mean $D^0$ lifetimes. We measu…
We present measurements of the masses and widths of four bottom baryon resonances, Sigma_b(*)+-, reconstructed in the Lambda_b pi+- hadron decay modes. The isospin mass splittings for the Sigma_b and Sigma_b* multiplets are extracted as well. The analysis is based on a data sample corresponding to an integrated luminosity of 6 fb^-1 .
We report the observation of new bottom baryon states. The most recent result is the observation of the baryon Ξ_b^- through the decay Ξ_b^- to J/ψΞ^-. The significance of the signal corresponds to 7.7 sigma and the Ξ_b^- mass is measured to be 5792.9 \pm 2.5(stat.) \pm 1.7(syst.) MeV/c^2. In addition we observe four resonances in the Λ_b^0 π^{\pm} spectra, consistent with the bottom baryons Σ_b^{(*)\pm}. All observations are in agreement with theoretical expectations.
I discuss the measurement of CP-violating asymmetries ($A_Γ$) between effective lifetimes of $D^0$ or $\bar{D}^0$ mesons. Fully reconstructed $D^0\to K^+ K^-$ and $D^0\to π^+π^-$ decays collected in $p\bar{p}$ collisions by the Collider Detector at Fermilab experiment and corresponding to a data set of $9.7$~fb$^{-1}$ of integrated luminosity are used. The flavor of the charm meson at production is determined by exploiting the decay $D^{*+} \to D^0 π^+$. Contamination from mesons originated in $b$-hadron decays is subtracted from the sample. Signal yields as functions of the observed decay-tim…
For data collected with the CDF Run II detector, measurements of the charm and bottom production cross-sections are presented. The results are based both on large samples of fully reconstructed hadron decay products of charm and bottom made available by the tracking triggers and on a calorimeter jet triggered sample tagged by the presence of a secondary vertex. The experimental data are compared with theoretical predictions from recent next-to-leading order (NLO) QCD calculations.
We report on mass and mean life measurements of several ground state $b-$baryons, using 9.6 $\textrm{fb}^{-1}$ of data from $p\bar p$ collisions at $\sqrt{s}=1.96$ TeV, and recorded with the Collider Detector at Fermilab. Data collected with triggers designed to collect events with $J/ψ\rightarrow μ^+ \, μ^-$ candidates and events with hadrons displaced from the beamline are used to measure the masses and lifetimes of $Λ_b, Ξ_b^-, Ξ_b^0$, and $Ω_b^-$. The first evidence for the process $Ω_b^- \rightarrow Ω_c^0 \, π^-$ is also shown. The results supersede our previous measurements of these quan…
Recent rate measurements of B_s mesons and Lambda_b baryons produced in sqrt{s} = 1.96 TeV proton-antiproton and Upsilon(5S) electron-positron collisions are reviewed, including the first observations of six new decay modes: B_s -> D_s^+ K^- (CDF), B_s -> D_s^- D_s^+ (CDF), B_s -> D_{s1}^-(2536) mu^+ nu_mu X (DZero), B_s -> phi gamma (Belle), Lambda_b -> p pi^- (CDF), and Lambda_b -> p K^- (CDF). Also examined are branching-fraction measurements or limits for the B_s -> D_s^{(*)} D_s^{(*)} modes (Belle, CDF, and DZero), the B_s -> gamma gamma radiative penguin decay (Belle), and three two-body…
From a study of the X(3872) mass and width based on the world's largest sample of $X(3872)\to J/ψπ^+π^-$ decays, we find that our X(3872) signal is consistent with a single state, and leads to the most precise measurement of the X(3872) mass. We also report the recent evidence for a new narrow structure, Y(4140), decaying to the $J/ψϕ$ final state, in exclusive $B^+\to J/ψϕK^+$ decays in a data sample corresponding to an integrated luminosity of 2.7 \ifb collected at the CDF II detector. This narrow structure with its mass well above open charm pairs is unlikely to be a candidate for a convent…
Using data from proton-antiproton collisions at Ecms=1.96 TeV recorded by the CDF II detector at the Fermilab Tevatron, evidence for the excited resonance state Lambda_b* is presented in its Lambda_b0 pi+ pi- decay, followed by the Lambda_b0 -->Lambda_c+ (-->proton K- pi+) pi- decays. The analysis is based on a data sample corresponding to an integrated luminosity of 9.6/fb collected by an online event selection based on charged-particle tracks displaced from the proton-antiproton interaction point. The significance of the observed signal is 3.5 Gaussian sigmas. The mass of the observed state …
A review of the experimental results on charmed baryons, with an accent on those reported most recently. Talk given at FPCP conference, U. Penn, May 2002.
Recent results on open charm production at HERA are presented. Charm quarks are identified via the reconstruction of D-mesons. The charm contribution to the proton structure function is shown. Evidence for an exotic anti-charmed baryon state observed by H1 is presented. The data show a narrow resonance in the D*p invariant mass combination at 3099+-3(stat)+-5(syst) MeV. The resonance is interpreted as an anti-charmed baryon with minimal constituent quark content uuddcbar together with its charge conjugate. Such a signal is not observed in a similar preliminary ZEUS analysis.
We present recent CDF results based on approximately 1 fb$^{-1}$ of $p\bar p$ collisions at $\sqrt s = 1.96$ TeV delivered at Fermilab Tevatron. Results shown include the observation of the $B_s$ oscillation frequency, the first observation of bottom baryon $Σ_b^{(*)\pm}$ states, updates on $B$ hadrons lifetimes, and searches for rare decays in the $b\to sμ^+μ^-$ transition and in charmless two-body B decays.
Using data from proton-antiproton collisions at Ecms=1.96 TeV recorded by the CDF II detector at the Fermilab Tevatron, we present evidence for the excited resonance state Lambda_b* in its fully reconstructed decay mode to Lambda_b0 pi+ pi- where Lambda_b0 -->Lambda_c+ (-->proton K- pi+) pi-. The analysis is based on a data sample corresponding to an integrated luminosity of 9.6/fb collected by an online event selection based on tracks displaced from the proton-antiproton interaction point. The local significance of the observed signal is 4.6 Gaussian sigmas. while the significance of the sign…
We report recent observations of baryonic B decays with charmless and charmed baryons in the final state. We show the angular distributions of the di-baryon low-mass enhancements in the charmless three-body baryonic B decays andthe branching fractions of B decays with two charmed baryons or charmonium in the final states. We also report the observation of the decay $η_c \to Λ\barΛ$ at Belle.
We report on several studies of charm baryon production and decays by the BaBar collaboration. We confirm previous observations of the $Ξ_c^{'0/+}$, $Ξ_c(2980)^+$ and $Ξ_c(3077)^+$ baryons, measure branching ratios for Cabibbo-suppressed $Λ_c^+$ decays and use baryon decays to study the properties of the light-quark baryons, $Ω^-$ and $Ξ(1690)^0$.
Recent studies of charmed baryon spectroscopy, performed by the Belle collaboration, are briefly described. We report the observation of an isotriplet of baryons $Σ_c(2800)$ and evidence for two new baryons $Ξ_{cx}(2980)$ and $Ξ_{cx}(3077)$. Finally we present a precise determination of the masses of $Ξ_c$ and $Ξ_c(2645)$.
The angular distributions of the baryon-antibaryon low-mass enhancements seen in the charmless three-body baryonic B decays B^+ \to p pbar K^+, B^0 \to p pbar K_S^0, and B^0 \to p Lambdabar pi^- are reported. Searches for the pentaquarks Theta^+ and Theta^{++} in the relevant decay modes and possible glueball states in the p pbar systems are presented. The analysis is based on a 140 fb^{-1} data sample recorded on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider.
Using ~13.7 fb^{-1} of e^+e^- collision data recorded at near the Upsilon(4S) resonance by the CLEO II and CLEO II.V detector configurations on the Cornell Electron Storage Ring, we present the world's most precise measurements of the Sigma_c^0, Sigma_c^+, and Sigma_c^{++} charmed-baryon masses as well as the first measurements of the intrinsic widths of the Sigma_c^0 and Sigma_c^{++} baryons. We also report on the first observation and mass measurement of the Sigma_c^{*+} charmed baryon, M(Sigma_c^{*+}) - M(Lambda_c^+) = (231.0 +- 1.1[stat] +- 2.0[syst]) MeV/c^2, and the first CLEO observatio…
Results are presented for the 500 GeV/c pion production asymmetry and polarization of the Lambda_c (anti-Lanbda_c) charmed baryon from Fermilab experiment E791. An analysis of the decay to the p anti-K pi final state is described. Resonant sub-channel fractions and phases are given and possible resonant effects in the low mass p anti-K system discussed. Significant decay to Lambda_c --> Delta++ K- establishes for the first time the importance of a W exchange mechanism in charmed baryon decay.
We report the recent results of charmed baryon decays, based on the data collected by the Belle experiment at the KEKB collider. This includes the observation of the doubly Cabibbo-suppressed decay $Λ_c^+\toπ^-K^+p$, search for the decay $Λ_c^+\toϕp π^0$, and the branching fraction measurement of $Λ_c^+\toπ^+K^-pπ^0$.
The SELEX experiment (E781) at Fermilab has candidates for high mass states decaying to Lambda_c+ K- pi+ and Lambda_c+ K- pi+ pi+, Cabibbo-allowed decay modes of doubly-charmed baryons Xi_cc+ and Xi_cc++. The masses are consistent with theoretical considerations, but the spectroscopy is surprising. Limited lifetime information suggests that tau_{Xi_cc++} \sim tau_{Xi_cc+}.
Some recent CDF results on heavy quarks (mainly $b$) are presented, including baryon masses and lifetimes, CP violation in charmless baryon decays, $B_c$ production, $A_{FB}$ at high $m(b \bar b)$, and excited $B$ mesons. Typographic corrections.
Spectroscopy and strong decays of the charmed baryons are reviewed. Possible spin-parity quantum numbers of several newly observed charmed baryon resonances are discussed. Strong decays of charmed baryons are analyzed in the framework of heavy hadron chiral perturbation theory in which heavy quark symmetry and chiral symmetry are synthesized.
Recent measurements of charm-baryon production at midrapidity by the ALICE collaboration show baryon-to-meson yield ratios significantly higher than those measured in $\rm e^+e^-$ collisions, suggesting that the charm fragmentations are not universal across different collisions systems. Thus, measurements of charm-baryon production are crucial to study the charm quark hadronisation in proton--proton (pp) collisions. In proton--lead (p--Pb) collisions, the measurements of charm baryons provide important information about cold nuclear matter effects and help to understand how the possible presen…
We report a measurement of the difference (Delta Acp) between time-integrated CP--violating asymmetries in D0-> K+ K- and D0-> pi+pi- decays reconstructed in the full data set of proton-antiproton collisions collected by the Collider Detector at Fermilab, corresponding to 9.7 fb-1 of integrated luminosity. The strong decay D*+->D0 pi+ is used to identify the charm meson at production as D0 or anti-D0. We measure Delta Acp = [-0.62 +- 0.21 (stat) +- 0.10 (syst)] %, which differs from zero by 2.7 Gaussian standard deviations.This result supports similar evidence for CP violation in charm-quark d…
With the one-boson-exchange model we have studied the possible existence of the very loosely bound hidden-charm molecular baryons composed of anti-charmed meson and charmed baryon. Our numerical results indicate that there exist $Σ_c\bar{D}^*$ states with $I(J^P)=1/2(1/2^-), 1/2(3/2^-), 3/2(1/2^-), 3/2(3/2^-)$ and $Σ_c\bar{D}$ state with $3/2(1/2^-)$. But the $Λ_c \bar{D}$ and $Λ_c \bar{D}^*$ molecular states do not exist.
The CLEO Collaboration recently has announced the discovery of an excited charmed and strange baryon. We estimate the expected width of this new member of the Xi_c family. We discuss the phenomenology of the excited csq and css states, and consider what additional charmed baryons might be observable in the future. We point out that the final state Xi_c + K could be an interesting new channel to examine.
Recent measurements of prompt charm-baryon production at midrapidity in pp and p--Pb collisions show baryon-to-meson yield ratios significantly higher than those in $\rm e^+e^-$ collisions, suggesting that the charm fragmentation is not universal across different collision systems. Thus, more precise and broader measurements of prompt charm-baryon production are crucial to study the charm quark hadronization in a partonic-rich environment like the one produced in pp collisions at the LHC energies. Prompt charm baryon-to-meson yield ratios in proton--nucleus collisions provide important informa…
After the discovery of the double-charm baryon $Ξ_{cc}^{++}$ by LHCb, one of the most important topics is to search for the bottom-charm baryons which contain a $b$ quark, a $c$ quark and a light quark. In this work, we study the two-body non-leptonic weak decays of a bottom-charm baryon into a spin-$1/2$ bottomed baryon and a light pseudoscalar meson with the short-distance contributions calculated under the factorization hypothesis and the long-distance contributions considering the final-state-interaction effects. The branching fractions of all fifty-seven decay channels are estimated. The …
Using information on B-meson fragmentation functions from CERN LEP 1 and adopting the nonrelativistic QCD factorization formalism proposed by Bodwin, Braaten, and Lepage, we predict the transverse-momentum distribution of J/psi mesons originating from the inclusive decays of b hadrons produced in p p-bar collisions at the Fermilab Tevatron. We determine the relevant colour-octet charmonium matrix elements from fits to CDF data on prompt charmonium hadroproduction and to CLEO data on charmonium production from B-meson decay. Our predictions are found to agree well with recent CDF and D0 data.
Several baryons containing a heavy b-quark, the b-baryons, have been discovered. The charmless two-body decays of b-baryons can provide a new platform for CP violating studies in a similar way as charmless two-body decays of B-meson. In b-baryon decays there are new CP violating observable related to baryon polarization. We show that in the flavor $SU(3)$ limit there exist relations involve different combinations of the decay amplitudes compared with those in CP violating rate asymmetry. These new relations therefore provide interesting tests for the mechanism of CP in the standard model (SM) …
We present a new method for detection of multiply charmed baryons via their decays into strange baryons, using `strangeness tracking'. This method makes use of the state-of-the-art upgraded silicon detectors in ALICE during Runs 3, 4 and beyond will enable the novel possibility of tracking strange hadrons directly before they decay, leading to a very significant improvement in impact-parameter resolution. In this work, we will discuss how this new technique will be crucial to distinguish secondary strange baryons originating from charm decays from primary strange baryons. This is a particularl…
We study the mass spectrum of baryons with two and three charmed quarks. For double charm baryons the spin splitting is found to be smaller than standard quark-model potential predictions. This splitting is not influenced either by the particular form of the confining potential or by the regularization taken for the contact term of the spin-spin potential. We consistently predict the spectra for triply charmed baryons.
