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

A strategy to compute the b-quark mass with non-perturbative accuracy

We describe a strategy for a non-perturbative computation of the b-quark mass to leading order in 1/m in the Heavy Quark Effective Theory (HQET). The approach avoids the perturbative subtraction of power law divergencies, and the continuum limit may be taken. First numerical results in the quenched approximation demonstrate the potential of the method with a preliminary result m_b(4GeV)=4.56(2)(7) GeV. In principle, the idea may also be applied to the matching of composite operators or the computation of 1/m corrections in HQET.Comment: Lattice2001(heavyquark) ; 3 page

A High Statistics Lattice Calculation of The B-meson Binding Energy

We present a high statistics lattice calculation of the B--meson binding energy $\overline{\Lambda}$ of the heavy--quark inside the pseudoscalar B--meson. Our numerical results have been obtained from several independent numerical simulations at $\beta=6.0$, $6.2$ and $6.4$, and using, for the meson correlators, the results obtained by the APE group at the same values of $\beta$. Our best estimate, obtained by combining results at different values of $\beta$, is $\overline{\Lambda}=180^{+30}_{-20}$ MeV. For the $\overline{MS}$ running mass, we obtain $\overline{m}_{b}(\overline{m}_{b})=4.15 \pm 0.05 \pm 0.20$ GeV, in reasonable agreement with previous determinations. The systematic error is the truncation of the perturbative series in the matching condition of the relevant operator of the Heavy Quark Effective Theory.Comment: Latex, 13 pages, 1 figure appended in uuencoded gzip.tar.fil

Infrared Renormalons and Finite Volume

We analyze the perturbative expansion of a condensate in the O(N) non-linear sigma model for large N on a two dimensional finite lattice. On an infinite volume this expansion is affected by an infrared renormalon. We extrapolate this analysis to the case of the gluon condensate of Yang-Mills theory and argue that infrared renormalons can be detected by performing perturbative studies even on relatively small lattices.Comment: LaTeX file, 6 figures in postscrip

On The Difficulty of Computing Higher-Twist Corrections

We discuss the evaluation of power corrections to hard scattering and decay processes for which an operator product expansion is applicable. The Wilson coefficient of the leading-twist operator is the difference of two perturbative series, each of which has a renormalon ambiguity of the same order as the power corrections themselves, but which cancel in the difference. We stress the necessity of calculating this coefficient function to sufficiently high orders in perturbation theory so as to make the uncertainty of the same order or smaller than the relevant power corrections. We investigate in some simple examples whether this can be achieved. Our conclusion is that in most of the theoretical calculations which include power corrections, the uncertainties are at least comparable to the power corrections themselves, and that it will be a very difficult task to improve the situation.Comment: 27 pages, uuencoded file containing latex source and axodraw.sty fil

Can early switch to rituximab-bendamustine in a patient with follicular non-Hodgkin lymphoma progressing during R-CHOP be considered frontline treatment?: A case report

RATIONALE: Follicular non-Hodgkin lymphoma (fNHL) is a neoplasm characterized by an indolent course and chemosensitivity, but also by disease recurrence. Bendamustine is often used as frontline treatment or second line. HEADING DIAGNOSIS:: fNHL. PATIENT CONCERNS: A 63-year-old Caucasian male with diagnosis of fNHL lymphoma underwent to cyclophosphamide, doxorubicin, vincristine, and prednisone associated with rituximab chemoimmunotherapy, during which interim reevaluation showed progressive disease and severe toxicity. INTERVENTIONS: Early switch to rituximab-bendamustine. OUTCOMES: This regimen was well tolerated, patient compliance was optimal, there were no delays in administration and no infectious episodes. An interim reevaluation after 3 courses revealed that the patient was fit, the blood cell count was normal, and lymphadenopathies and nocturnal sweating had completely regressed. Of note, the PET/CT scan did not show fluorodeoxyglucose pathological uptake, clearly confirming disease regression. LESSONS: Early switching to a bendamustine-rituximab-based scheme, even during conventional chemotherapy, decreases toxicity and reduces the risk of treatment interruption or delay, with favorable effects on overall response and prognosis

An unquenched lattice QCD calculation of the mass of the bottom quark

We compute the b quark mass from dynamical lattice QCD with clover quarks. The calculation is done at a fixed lattice spacing with sea quark masses as low as half the strange quark mass. Our final result is m_b(m_b} = 4.25(2)(11) GeV, where the first error is statistical and the last error is the systematic uncertainty.Comment: 10 page

Perturbative expansions from Monte Carlo simulations at weak coupling: Wilson loops and the static-quark self-energy

Perturbative coefficients for Wilson loops and the static-quark self-energy are extracted from Monte Carlo simulations at weak coupling. The lattice volumes and couplings are chosen to ensure that the lattice momenta are all perturbative. Twisted boundary conditions are used to eliminate the effects of lattice zero modes and to suppress nonperturbative finite-volume effects due to Z(3) phases. Simulations of the Wilson gluon action are done with both periodic and twisted boundary conditions, and over a wide range of lattice volumes (from $3^4$ to $16^4$) and couplings (from $\beta \approx 9$ to $\beta \approx 60$). A high precision comparison is made between the simulation data and results from finite-volume lattice perturbation theory. The Monte Carlo results are shown to be in excellent agreement with perturbation theory through second order. New results for third-order coefficients for a number of Wilson loops and the static-quark self-energy are reported.Comment: 36 pages, 15 figures, REVTEX documen

Towards precision heavy flavour physics from lattice QCD

I convey an idea of the significant recent progress, which opens up good perspectives for high-precision ab-initio computations in heavy flavour physics based on lattice QCD. This report focuses on the strategy and the challenges of fully non-perturbative investigations in the B-meson sector, where the b-quark is treated within an effective theory, as followed by the ALPHA Collaboration. As an application, I outline its use to determine the b-quark mass and summarize the status of our ongoing project in the two dynamical flavour theory.Comment: Invited talk at the Third Workshop on Theory, Phenomenology and Experiments in Heavy Flavour Physics, 5-7 July 2010, Capri, Italy; 8 pages including figures, latex2e, uses espcrc2.st

Large Wilson loops with overlap and clover fermions: Two-loop evaluation of the b-quark mass shift and the quark-antiquark potential

We compute, to two loops in pertubation theory, the fermionic contribution to rectangular RxT Wilson loops, for different values of R and T. We use the overlap fermionic action. We also employ the clover action, for comparison with existing results in the literature. In the limit R, T -> Infinity our results lead to the shift in the b-quark mass. We also evaluate the perturbative static potential as T -> Infinity.Comment: 24 pages, 14 figures, 14 table