14,601 research outputs found

    B Physics on the Lattice: Λ\overline{\Lambda}, λ1\lambda_{1}, mb(mb)\overline{m}_{b}(\overline{m}_{b}), λ2\lambda_2, B0Bˉ0B^{0}-\bar{B}^{0} mixing, \fb and all that

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    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, Λ\overline{\Lambda} and the kinetic energy of the b quark in the B meson, λ1\lambda_1, which due to the presence of power divergences require a non--perturbative renormalization to be defined; the MS\overline{MS} running mass of the b quark, mb(mb)\overline{m}_{b}(\overline{m}_{b}); the BB^{*}--BB mass splitting, whose value in the HQET is determined by the matrix element of the chromo--magnetic operator between B meson states, λ2\lambda_2; the B parameter of the B0B^{0}--Bˉ0\bar{B}^{0} mixing, BBB_{B}, and the decay constant of the B meson, fBf_{B}. All these quantities have been computed using a sample of 600600 gauge field configurations on a 243×4024^{3}\times 40 lattice at β=6.0\beta=6.0. For Λ\overline{\Lambda} and mb(mb)\overline{m}_{b}(\overline{m}_{b}), we obtain our estimates by combining results from three independent lattice simulations at β=6.0\beta=6.0, 6.26.2 and 6.46.4 on the same volume.Comment: 3 latex pages, uses espcrc2.sty (included). Talk presented at LATTICE96(heavy quarks

    Results from a Non-Perturbative Renormalization of Lattice Operators

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    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 163×3216^3 \times 32 lattice, at β=6.0\beta=6.0.Comment: 3 pages postscript file. Contribution to Lattice '9

    Logical Specification and Analysis of Fault Tolerant Systems through Partial Model Checking

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    This paper presents a framework for a logical characterisation of fault tolerance and its formal analysis based on partial model checking techniques. The framework requires a fault tolerant system to be modelled using a formal calculus, here the CCS process algebra. To this aim we propose a uniform modelling scheme in which to specify a formal model of the system, its failing behaviour and possibly its fault-recovering procedures. Once a formal model is provided into our scheme, fault tolerance - with respect to a given property - can be formalized as an equational µ-calculus formula. This formula expresses in a logic formalism, all the fault scenarios satisfying that fault tolerance property. Such a characterisation understands the analysis of fault tolerance as a form of analysis of open systems and thank to partial model checking strategies, it can be made independent on any particular fault assumption. Moreover this logical characterisation makes possible the fault-tolerance verification problem be expressed as a general µ-calculus validation problem, for solving which many theorem proof techniques and tools are available. We present several analysis methods showing the flexibility of our approach

    Lattice computation of structure functions

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    Recent lattice calculations of hadron structure functions are described.Comment: Plenary talk presented at LATTICE96, LaTeX, 7 pages, 5 figures, espcrc2.sty and epsfig.sty include

    A High-Statistics Lattice Calculation of λ1\lambda_1 and λ2\lambda_2 in the BB meson

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    We present a high-statistics lattice calculation of the kinetic energy λ1/2mb-\lambda_1/2 m_b of the heavy quark inside the BB-meson and of the chromo-magnetic term λ2\lambda_2, related to the BB^*--BB mass splitting, performed in the HQET. Our results have been obtained from a numerical simulation based on 600 gauge field configurations generated at β=6.0\beta=6.0, on a lattice volume 243×4024^3 \times 40 and using, for the meson correlators, the results obtained with the SW-Clover O(a)O(a) improved lattice action for the light quarks. For the kinetic energy we found λ1=Bhˉ(iD)2hB/(2MB)=(0.09±0.14)-\lambda_1=\langle B \vert \bar h (i\vec{D})^{2} h \vert B \rangle /(2 M_B )=-(0.09 \pm 0.14)~GeV2^2, which is interesting for phenomenological applications. We also find λ2=0.07±0.01\lambda_2= 0.07 \pm 0.01 GeV2^2, corresponding to MB2MB2=4λ2=0.280±0.060M^2_{B^*}-M^2_B= 4 \lambda_2= 0.280 \pm 0.060 GeV2^2, which is about one half of the experimental value. The origin of the discrepancy with the experimental number needs to be clarified.Comment: 26 pages, latex, 5 figure

    DEPENDENCE OF THE CURRENT RENORMALISATION CONSTANTS ON THE QUARK MASS

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    We study the behaviour of the vector and axial current renormalisation constants ZVZ_V and ZAZ_A as a function of the quark mass, mqm_q. We show that sizeable O(amq)O(am_q) and O(g02amq)O(g_0^2 a m_q) systematic effects are present in the Wilson and Clover cases respectively. We find that the prescription of Kronfeld, Lepage and Mackenzie for correcting these artefacts is not always successful.Comment: Contribution to Lattice'94, 3 pages PostScript, uuencoded compressed

    Hermite Calculus

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    We develop a new method of umbral nature to treat blocks of Her mite and of Hermite like poly- nomials as independent algebraic quantities. The Calculus we propose allows the formulation of a number of ”practical rules” allowing significant simplific ations in computational problem

    Computing the Slope of the Isgur-Wise Function

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    We propose a method for evaluating the slope (and higher derivatives) of the Isgur-Wise function at the zero recoil point using lattice simulations. These derivatives are required for the extrapolation of the experimental data for BDlνˉB\rightarrow D^*l\bar\nu decays to the zero recoil point, from which the VcbV_{cb} element of the CKM-matrix can be determined.Comment: Latex File Southampton Preprint 93/94-07; Rome Preprint 93/98

    Non-perturbative renormalization in kaon decays

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    We discuss the application of the MPSTV non-perturbative method \cite{NPM} to the operators relevant to kaon decays. This enables us to reappraise the long-standing question of the ΔI=1/2\Delta I=1/2 rule, which involves power-divergent subtractions that cannot be evaluated in perturbation theory. We also study the mixing with dimension-six operators and discuss its implications to the chiral behaviour of the BKB_K parameter.Comment: Talk presented at LATTICE96(improvement), LaTeX 3 pages, uses espcrc2, 2 postscript figure
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