Diquark-antidiquark states with hidden or open charm

Some features and predictions of a recently proposed model based on diquark-antidiquark bound states are illustrated. Its ability in accomodating newly discovered charmed resonances around 4 GeV is discussed.Comment: To appear in the proceedings of the HEP2005 International Europhysics Conference on High Energy Physics, July 21st-27th 2005, Lisboa, Portuga

Theoretical developments on Quartic Gauge Boson Couplings at LEP

The search for quartic anomalous gauge couplings (QAGC) at LEP requires appropriate predictions for the radiative processes e+ e- \to \nu\bar\nu \gamma\gamma, e+ e- \to q\bar{q}\gamma\gamma and e+ e- \to 4 fermions+\gamma. The current knowledge on dimension-six operators giving rise to QAGC is briefly reviewed, together with their implementation in event generators. The accuracy of calculations based on real approximations (used up to now for the LEP experimental analysis) is examined by comparing them with the available exact matrix element calculations.Comment: LaTeX, JHEP style, 5 pag. Talk presented at EPS HEP2001, Budapest, Hungary, 12 - 18 July, 200

TOPAZ0 2.0 - A Program for Computing De-Convoluted and Realistic Observables Around the Z0Z^0 Peak

The program {\tt TOPAZ0} is designed for computing $Z^0$ parameters, de-convoluted and QED-dressed cross sections and forward-backward asymmetries of $e^+ e^-$ annihilation into fermion pairs and of Bhabha scattering around the $Z^0$ peak, over both a completely inclusive experimental set-up and a realistic one, i.e. with cuts on acollinearity, energy or invariant mass and angular acceptance of the outgoing fermions. The new version, 2.0, offers the possibility of imposing different experimental cuts on cross sections and forward-backward asymmetries in a single run, and includes radiative corrections whose effect can become relevant in view of the present and foreseen experimental accuracy. Moreover, an additional option is included, which allows an estimate of the theoretical uncertainty due to unknown higher-order effects, both of electroweak and QCD origin. With respect to the version 1.0, the code is available in the form of {\tt SUBROUTINE}, in order to render more viable the use of the program for aims not planned by the {\tt TOPAZ0} package itself.Comment: 12 pages, LateX, no macros, no figure

SABSPV - A Monte Carlo Integrator for Small-Angle Bhabha Scattering

SABSPV is a code designed to perform a theoretical evaluation of small-angle Bhabha scattering cross sections by suitably matching fixed-order perturbative calculations and structure-function techniques. The implementation of realistic experimental triggering conditions is achieved by using Monte Carlo integration.Comment: 12 pages, LaTeX, no figures, no macro

Radiative four-fermion processes at LEP2

The production of four fermions plus a visible photon in electron-positron collisions is analyzed, with particular emphasis on the LEP2 energy range. The study is based on the calculation of exact matrix elements, including the effect of fermion masses. In the light of the present measurements performed at LEP, triple and quartic anomalous gauge couplings are taken into account. Due to the presence of a visible photon in the final state, particular attention is paid to the treatment of higher-order QED corrections. Explicit results for integrated cross sections and differential distributions are shown and commented. The features of the Monte Carlo program WRAP, used to perform the calculation and available for experimental analysis, are described.Comment: LaTeX, 14 pages, 6 tables, 13 figures. Numerical results added, version to appear in Eur. Phys. J.

The observation of light nuclei at ALICE and the X(3872) conundrum

The new data reported by ALICE on the production of light nuclei with pT < 10 GeV in Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV are used to compute an order-of-magnitude estimate of the expected production cross sections of light nuclei in proton-proton collisions at high transverse momenta. We compare the hypertriton, helium-3 and deuteron production cross sections to that of X(3872), measured in prompt pp collisions by CMS. The results we find suggest a different production mechanism for the X(3872), making questionable any loosely bound molecule interpretation.Comment: 5 pages, 2 figures. Version accepted on PR