We have measured the Lambda_b lifetime using the exclusive decay Lambda_b to J/psi Lambda, based on 1.2 fb-1 of data collected with the D0 detector during 2002-2006. From 171 reconstructed Lambda_b decays, where the J/psi and Lambda are identified via the decays J/psi to mu+ mu- and Lambda to p pi, we measured the Lambda_b lifetime to be tau(Lambda_b) = 1.218(+0.130,-0.115)(stat) +/- 0.042(syst)ps. We also measured the B0 lifetime in the decay B0 to J/psi(mu+ mu-)K0_S(pi+ pi-) to be tau(B0) = 1.501(+0.078,-0.074)(stat) +/ -0.050(syst)ps, yielding a lifetime ratio of tau(Lambda_b)/tau(B0) = 0.811(+0.096,-0.087)(stat) +/ -0.034(syst). These measurements are consistent with the current world averages and support the shorter lifetime of the Lambda_b with respect to B mesons, in contrast to another recent measurement of significant precision.
We report on a study of the isospin-violating and conserving decays of the J/psi and psi(2S) charmonium state to Lambda Lambdabar pi0 and Lambda Lambdabar eta, respectively. The data are based on 225 million J/psi and 106 million psi(2S) events that were collected with the BESIII detector. The most accurate measurement of the branching fraction of the isospin-violating process J/psi ->Lambda Lambdabar pi0 is obtained, and the isospin-conserving processes J/psi ->Lambda Lambdabar eta and psi(2S) ->Lambda Lambdabar eta are observed for the first time. The branching fractions are measured to be B…
We measure the Lambda_b^0 lifetime in the fully reconstructed decay Lambda_b^0 -> J/psi Lambda^0 using 10.4 fb^-1 of ppbar collisions collected with the D0 detector at sqrt(s)=1.96 TeV. The lifetime of the topologically similar decay channel B^0 -> J/psi K^0_S is also measured. We obtain tau(Lambda_b^0) = 1.303 +- 0.075 (stat.) +- 0.035 (syst.) ps and tau(B^0) = 1.508 +- 0.025 (stat.) +- 0.043 (syst.) ps. Using these measurements, we determine the lifetime ratio of tau(Lambda_b^0)/tau(B^0) = 0.864 +- 0.052 (stat.) +- 0.033 (syst.).
The Lambda(b) differential production cross section and the cross section ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Lambda(b) decays reconstructed in the exclusive final state J/Psi Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and Lambda to proton pion, using a data sample corresponding to an integrated luminosity of 1.9 inverse femtobarns. The product of the cross se…
A measurement of the parity-violating decay asymmetry parameter, alpha_b, and the helicity amplitudes for the decay Lambda_b->J/psi(mu mu)+Lambda(p pi) is reported. The analysis is based on 1400 Lambda_b and anti-Lambda_b baryons selected in 4.6/fb of proton-proton collision data with a center-of-mass energy of 7 TeV recorded by the ATLAS experiment at the LHC. By combining the Lambda_b and anti-Lambda_b samples under the assumption of CP conservation, the value of alpha_b is measured to be 0.30+/-0.16(stat)+/-0.06(syst). This measurement provides a test of theoretical models based on perturba…
The polarizations of prompt J/psi and psi(2S) mesons are measured in proton-proton collisions at sqrt(s) = 7 TeV, using a dimuon data sample collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.9 inverse femtobarns. The prompt J/psi and psi(2S) polarization parameters lambda[theta], lambda[phi], and lambda[theta,phi], as well as the frame-invariant quantity lambda(tilde), are measured from the dimuon decay angular distributions in three different polarization frames. The J/psi results are obtained in the transverse momentum range 14 < pt < 70 GeV, in the r…
In this contribution we report on the investigations of the exclusive production of J/psi and psi(2S) states in proton-proton and nucleus-nucleus reactions at the LHC using the theoretical framework of light-cone dipole formalism.
We report on a measurement of $b$-hadron lifetimes in the fully reconstructed decay modes B^+ -->J/Psi K+, B^0 --> J/Psi K*, B^0 --> J/Psi Ks, and Lambda_b --> J/Psi Lambda using data corresponding to an integrated luminosity of 4.3 ${\rm fb}^{-1}$, collected by the CDF II detector at the Fermilab Tevatron. The measured lifetimes are $τ$B^+ = $1.639 \pm 0.009 ({\rm stat}) \pm 0.009 {\rm (syst) ~ ps}$, $τ$B^0 = $1.507 \pm 0.010 ({\rm stat}) \pm 0.008 {\rm (syst) ~ ps}$ and $τ$Lambda_b = $1.537 \pm 0.045 ({\rm stat}) \pm 0.014 {\rm (syst) ~ ps}$. The lifetime ratios are $τ$B^+/$τ$B^0 = $1.088 \p…
We present properties of weakly decaying bottom baryons, Xi_b and Omega_b, using 4.2 fb^-1 of data from p-pbar collisions at sqrt{s}=1.96 TeV, and recorded with the Collider Detector at Fermilab. We report the observation of the Omega_b through the decay chain Omega_b -> J/psi Omega^-, where J/psi -> mu^+ mu^-, Omega^- -> Lambda K^-, and Lambda -> p pi^-. Significance of the observed signal is estimated to be 5.5 Gaussian standard deviations. The Omega_b mass and lifetime are measured to be 6054.4 +- 6.8 (stat.) +- 0.9 (syst.) MeV/c^2 and 1.13^{+0.53}_{-0.40}(stat.) +- 0.02(syst.) ps, respecti…
We report the observation of the bottom, doubly-strange baryon Omega^-_b through the decay chain Omega^-_b -> J/psi Omega^-, where J/psi -> mu^+ mu^-, Omega^- -> Lambda K^-, and Lambda -> p pi^-, using 4.2 fb^{-1} of data from p\bar p collisions at sqrt{s}=1.96 TeV, and recorded with the Collider Detector at Fermilab. A signal is observed whose probability of arising from a background fluctuation is 4.0 * 10^{-8}, or 5.5 Gaussian standard deviations. The Omega^-_b mass is measured to be 6054.4 +/- 6.8 (stat.) +/- 0.9 (syst.) MeV/c^2. The lifetime of the Omega^-_b baryon is measured to be 1.13^…
We have observed the reactions p+pbar --> p+X+pbar, with X being a centrally produced J/psi, psi(2S) or chi_c0, and gamma+gamma --> mu+mu-, in proton- antiproton collisions at sqrt{s} = 1.96 TeV using the Run II Collider Detector at Fermilab. The event signature requires two oppositely charged muons, each with pseudorapidity |eta| < 0.6, with M(mumu) in [3.0,4.0] GeV/c2, and either no other particles, or one additional photon, detected. The J/psi and the psi(2S) are prominent, on a continuum consistent with the QED process gamma+gamma --> mu+mu-. Events with a J/psi and an associated photon ca…
The cross section for exclusive psi(2S) ultraperipheral production at the LHC is calculated using gluon parametrisations extracted from exclusive J/psi measurements performed at HERA and the LHC. Predictions are given at leading and next-to-leading order for pp centre-of-mass energies of 7, 8 and 14 TeV, assuming the non-relativistic approximation for the psi(2S) wave function.
A measurement of the Lambda(b)0 lifetime using the decay Lambda(b)0 to J/Psi Lambda in proton-proton collisions at sqrt(s) = 7 TeV is presented. The data set, corresponding to an integrated luminosity of about 5 inverse femtobarns, was recorded with the CMS experiment at the Large Hadron Collider using triggers that selected dimuon events in the J/Psi mass region. The Lambda(b)0 lifetime is measured to be 1.503 +/- 0.052 (stat.) +/- 0.031 (syst.) ps.
In this work we investigate the exclusive photoproduction of J/psi and the radially excited psi(2S) state off nucleon in proton-proton collisions. The theoretical framework considered in the analysis is the light-cone dipole formalism and predictions are done for proton-proton collisions at the CERN-LHC energy of 7 TeV. The theoretical uncertainties are investigated and comparison is done to the recent LHCb Collaboration data for the exclusive charmonium production.
The Collider Detector at Fermilab, CDF, observed for the first time in hadron-hadron collisions photon-photon to e+e- and mu+mu-, photon-pomeron to J/psi and psi(2S), and pomeron-pomeron to photon+photon and to chi_c. Exclusive pi+pi- production by double pomeron exchange was also measured at p+pbar CM energies 900 GeV and 1960 GeV, showing f0 and f2 resonance structures.
We review recent experimental results on Bd and Bs mesons decays by the BaBar and Belle experiments. These include measurements of the color-suppressed decays B0bar to D(*)0h0, h0=pi0, eta, etaprime, omega, observation of the baryonic decay B0bar to Lambdac+ Lambdabar K-, measurements of the charmless decays B to eta h, h=K, pi, B to Kpi and observation of CP eigenstates in the Bs decays: B0s to J/psi f0(980), B0s to J/psi f0(1370) and B0s to J/psi eta. The theoretical implications of these results will be considered.
Using a sample of $1.06\times10^8$ $ψ^\prime$ mesons collected with the BESIII detector at the BEPCII $e^+e^-$ collider and $χ_{cJ}$ mesons produced via radiative transitions from the $ψ^\prime$, we report the first observation for $ψ^\prime\to \bar{p}K^+Σ^0 +c.c.$ (charge-conjugate), as well as improved measurements for the $χ_{cJ}$ hyperon decays $χ_{cJ}\to\bar{p}K^+Λ+c.c.$. The branching fractions are measured to be $\mathcal{B}(ψ^\prime\to \bar{p}K^+Σ^0+c.c)= (1.67\pm0.13\pm0.12)\times10^{-5}$, $\mathcal{B}(χ_{c0}\to\bar{p}K^+Λ+c.c.)= (13.2\pm0.3\pm1.0)\times10^{-4}$, $\mathcal{B}(χ_{c1}\t…
We studied the decay psi(2S) to gamma eta_c(2S) with 25.9 million psi(2S) events collected with the CLEO-c detector. No psi(2S) to gamma eta_c(2S) decays were observed in any of the eleven exclusive eta_c(2S) decay modes studied. The product branching fraction upper limits were determined for all modes. The 90% confidence level upper limit of branching fraction of psi(2S) to gamma eta_c (2S) was obtained.
We present the latest B physics results from the CDF experiment at the Fermilab Tevatron collider. We focus on a number of analyses, including a measurement of the forward-backward asymmetry of B -> K^(*) mu mu decays, determination of the CP violating phase sin2beta_s in B^0_s-> J/psi phi decays, B -> J/psi X lifetime measurements, observation of resonance structure in Lambda_b -> Lambda_c 3pi, and Upsilon(1S) polarization.
Using 805 pb^-1 of e+e- annihilation data taken with the CLEO-c detector at psi(3770), sqrt{s}=3770 MeV, we report the first measurements of the electromagnetic form factors of the Lambda0, Sigma0, Sigma+, Xi0, Xi-, and Omega- hyperons for the large timelike momentum transfer of |Q^2|=14.2 GeV^2. The form factors for the different hyperons are found to vary by nearly a factor two. It is found that |G_M(Lambda0)|=1.66(24) x |G_M(Sigma0)|. The Lambda0 and Sigma0 hyperons have the same uds quark content, but differ in their isospin, and therefore the spin of the $ud$ quark pair. It is suggested t…
As a test of the color-singlet mechanism of the nonrelativistic QCD (NRQCD) factorization approach, we consider the exclusive two-quarkonium productions in electron-positron annihilation e+ e- -> eta_c + gamma and e+ e- -> J/psi + J/psi at B factories. The cross sections are computed to the next-to-leading order in alpha_s and are resummed to all orders in half the relative velocity v of the charm quark in each meson rest frame. The available theoretical prediction of the cross section for e+ e- -> J/psi + eta_c at the same level of theoretical accuracies is consistent with the available exper…
B-hadrons are an ideal tool for advancing our current understanding of the flavor sector of the Standard Model (SM). The study of B-meson production and decays is one of the key physics themes at the Large Hadron Collider (LHC) thanks to the large production rate and the fact that B-hadrons are relatively easy to trigger on and identify due to their long lifetime and decays to muons. This talk presents the cross section measurement for the exclusive final state Bs->J/psi phi and an evaluation of the decay branching fraction from the previously published exclusive-B production cross sections. B…
A c.m. energy scan below the J/Psi peak foreseen in the next future at BESIII can probe the existence in all the exclusive possible final states of an interference pattern between the resonant e+e- => J/Psi => hadrons and non-resonant e+e+ => hadrons amplitudes. The relative phase of the strong J/Psi decay amplitude with respect to the electromagnetic one can hence be accessed for the first time in a model independent way.
