The e+ e- -> P1 P2 gamma processes close to the Phi peak: toward a model-independent analysis

We discuss the general decomposition and possible general parameterizations of the processes $e^+ e^- \to \gamma^* \to P_1 P_2 \gamma$, where $P_1 P_2=\pi^0 \pi^0$, $\pi^0\eta$, or $\pi^+\pi^-$, for $\sqrt{s}\approx M_\Phi$. Particular attention is devoted to the amplitude where the two pseudoscalar mesons are in a $J^{CP}= 0^{++}$ state, where we propose a general parameterization which should help to shed light on the nature of light scalar mesons.Comment: 12 pages, Late

On lattice chiral gauge theories

The Smit-Swift-Aoki formulation of a lattice chiral gauge theory is presented. In this formulation the Wilson and other non invariant terms in the action are made gauge invariant by the coupling with a nonlinear auxilary scalar field, omega. It is shown that omega decouples from the physical states only if appropriate parameters are tuned so as to satisfy a set of BRST identities. In addition, explicit ghost fields are necessary to ensure decoupling. These theories can give rise to the correct continuum limit. Similar considerations apply to schemes with mirror fermions. Simpler cases with a global chiral symmetry are discussed and it is shown that the theory becomes free at decoupling. Recent numerical simulations agree with those considerations

B Physics on the Lattice: Λ‾\overline{\Lambda}, λ1\lambda_{1}, m‾b(m‾b)\overline{m}_{b}(\overline{m}_{b}), λ2\lambda_2, B0−Bˉ0B^{0}-\bar{B}^{0} mixing, \fb and all that

We present a short review of our most recent high statistics lattice determinations in the HQET of the following important parameters in B physics: the B--meson binding energy, $\overline{\Lambda}$ and the kinetic energy of the b quark in the B meson, $\lambda_1$, which due to the presence of power divergences require a non--perturbative renormalization to be defined; the $\overline{MS}$ running mass of the b quark, $\overline{m}_{b}(\overline{m}_{b})$; the $B^{*}$--$B$ mass splitting, whose value in the HQET is determined by the matrix element of the chromo--magnetic operator between B meson states, $\lambda_2$; the B parameter of the $B^{0}$--$\bar{B}^{0}$ mixing, $B_{B}$, and the decay constant of the B meson, $f_{B}$. All these quantities have been computed using a sample of $600$ gauge field configurations on a $24^{3}\times 40$ lattice at $\beta=6.0$. For $\overline{\Lambda}$ and $\overline{m}_{b}(\overline{m}_{b})$, we obtain our estimates by combining results from three independent lattice simulations at $\beta=6.0$, $6.2$ and $6.4$ on the same volume.Comment: 3 latex pages, uses espcrc2.sty (included). Talk presented at LATTICE96(heavy quarks

The post-Higgs MSSM scenario: Habemus MSSM?

We analyze the Minimal Supersymmetric extension of the Standard Model that we have after the discovery of the Higgs boson at the LHC, the hMSSM (habemus MSSM?), i.e. a model in which the lighter $h$ boson has a mass of approximately 125 GeV which, together with the non-observation of superparticles at the LHC, indicates that the SUSY-breaking scale $M_S$ is rather high, $M_S > 1$ TeV. We first demonstrate that the value $M_h \approx 125$ GeV fixes the dominant radiative corrections that enter the MSSM Higgs boson masses, leading to a Higgs sector that can be described, to a good approximation, by only two free parameters. In a second step, we consider the direct supersymmetric radiative corrections and show that, to a good approximation, the phenomenology of the lighter Higgs state can be described by its mass and three couplings: those to massive gauge bosons and to top and bottom quarks. We perform a fit of these couplings using the latest LHC data on the production and decay rates of the light $h$ boson and combine it with the limits from the negative search of the heavier $H,A$ and $H^\pm$ states, taking into account the current uncertainties.Comment: 1+12 pages, pdflatex, 7 figure

Plasma antioxidants from chocolate

There is some speculation that dietary flavonoids from chocolate, in particular (-)epicatechin, may promote cardiovascular health as a result of direct antioxidant effects or through antithrombotic mechanisms. Here we show that consumption of plain, dark chocolate results in an increase in both the total antioxidant capacity and the (-)epicatechin content of blood plasma, but that these effects are markedly reduced when the chocolate is consumed with milk or if milk is incorporated as milk chocolate. Our findings indicate that milk may interfere with the absorption of antioxidants from chocolate in vivo and may therefore negate the potential health benefits that can be derived from eating moderate amounts of dark chocolate

Two-body non-leptonic decays on the lattice

We show that, under reasonable hypotheses, it is possible to study two-body non-leptonic weak decays in numerical simulations of lattice QCD. By assuming that final-state interactions are dominated by the nearby resonances and that the couplings of the resonances to the final particles are smooth functions of the external momenta, it is possible indeed to overcome the difficulties imposed by the Maiani-Testa no-go theorem and to extract the weak decay amplitudes, including their phases. Under the same assumptions, results can be obtained also for time-like form factors and quasi-elastic processes.Comment: 15 pages, 1 Postscript figur

Commissioning of the ATLAS Muon Trigger System with early data

An overview of the early results on commissioning and performance of the ATLAS Muon Trigger System is shown. The ATLAS Muon Trigger has been designed to cope with the high interaction rate expected at the LHC. The presented performance studies have been obtained using both cosmic-ray and 900GeV collision data

Results from a Non-Perturbative Renormalization of Lattice Operators

We propose a general renormalization method, which avoids completely the use of lattice perturbation theory. We present the results from its numerical applications to two-fermion operators on a $16^3 \times 32$ lattice, at $\beta=6.0$.Comment: 3 pages postscript file. Contribution to Lattice '9

Chiral behaviour of the lattice BKB_K-parameter with the Wilson and Clover Actions at β=6.0\beta = 6.0

We present results for the kaon $B$-parameter $B_K$ from a sample of $200$ configurations using the Wilson action and $460$ configurations using the SW-Clover action, on a $18^3 \times 64$ lattice at $\beta=6.0$. We compare results obtained by renormalizing the relevant operator with different ``boosted" values of the strong coupling constant $\alpha_s$. In the case of the SW-Clover action, we also use the operator renormalized non-perturbatively. In the Wilson case, we observe a strong dependence of $B_K$ on the prescription adopted for $\alpha_s$, contrary to the results of the Clover case which are almost unaffected by the choice of the coupling. We also find that the matrix element of the operator renormalized non-perturbatively has a better chiral behaviour. This gives us our best estimate of the renormalization group invariant $B$-parameter, $\hat B_K=0.86 \pm 0.15$.Comment: LaTeX, 17 pages, 3 postscript figures uuencode

Model independent determination of the shape function for inclusive B decays and of the structure functions in DIS

We present a method to compute, by numerical simulations of lattice QCD, the inclusive semileptonic differential decay rates of heavy hadrons and the structure functions which occur in deep inelastic scattering. The method is based on first principles and does not require any model assumption. It allows the prediction of the differential rate in B semileptonic decays for values of the recoiling hadronic mass W ~ sqrt(M_B Lambda_QCD), which is in the relevant region to extract |V_ub| from the end-point of the lepton spectrum in inclusive decays.Comment: 16 pages, LaTeX fil