Quenched and first unquenched lattice HQET determination of the Bs-Meson width difference

We present recent results for the prediction of the Bs lifetime difference from lattice Heavy Quark Effective Theory simulations. In order to get a next-to-leading order result we have calculated the matching between QCD and HQET and the two-loop anomalous dimensions in the HQET for all the \Delta B=2 operators, in particular for the operators which enter the width difference. We present results from quenched and, for the first time, from unquenched simulations. We obtain for the Bs lifetime difference, (\Delta\Gamma_Bs/\Gamma_Bs)^{(que.)}=(5.1+/- 1.9+/- 1.7)10^(-2) and (\Delta\Gamma_Bs/\Gamma_Bs)^{(unq.)}=(4.3+/- 2.0+/- 1.9)10^(-2) from the quenched and unquenched simulations respectivelyComment: Lattice 2000 (Heavy Quark Physics), 4 pages, LaTeX. Some misprints corrected. No result change

New Results From Lattice QCD: Non-Perturbative Renormalization and Quark Masses

For the first time, we compute non-perturbatively, i.e. without lattice perturbation theory, the renormalization constants of two-fermion operators in the quenched approximation at $\beta=6.0$, 6.2 and 6.4 using the Wilson and the tree-level improved SW-Clover actions. We apply these renormalization constants to fully non-perturbatively estimate quark masses in the $\bar{MS}$ scheme from lattice simulations of both the hadron spectrum and the Axial Ward Identity in the quenched approximation. Some very preliminary unquenched Wilson results obtained from the gluon configurations generated by the T$\chi$L Collaboration at $\beta=5.6$ and $N_{f}=2$ are also discussed.Comment: 4 pages, 2 figures. Invited talk given at the QCD 98 Euroconference, Montpellier, France, 2-8 July 199

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

Width difference in the Bs system from lattice HQET

We present recent results for the prediction of the Bs lifetime difference from lattice Heavy Quark Effective Theory simulations. In order to get a next-to-leading order result we have calculated the matching between QCD and HQET and the two loop anomalous dimension in the HQET for all the \Delta B=2 operators, in particular for the operators which enter in the width difference. We obtain for the Bs lifetime difference, (\Delta\Gamma_Bs/\Gamma_Bs)=(5.1+/- 1.9+/- 1.7)10^(-2).Comment: 4 pages, LaTeX. Talk given at International Conference on Hyperons, Charm and Beauty Hadrons, Valencia, Spain, 27-30 Jun 2000. Some misprints corrected. No result change

B-parameters of the complete set of matrix elements of (Delta B = 2) operators from the lattice

We compute on the lattice the ``bag'' parameters of the five (Delta B = 2) operators of the supersymmetric basis, by combining their values determined in full QCD and in the static limit of HQET. The extrapolation of the QCD results from the accessible heavy-light meson masses to the B-meson mass is constrained by the static result. The matching of the corresponding results in HQET and in QCD is for the first time made at NLO accuracy in the MSbar(NDR) renormalization scheme. All results are obtained in the quenched approximation.Comment: 27 pages (5 figures

B−BˉB - \bar B Mixing in the HQET

We present a high statistics, quenched lattice calculation of the B-parameters $B_{B_d}$ and $B_{B_s}$, computed at lowest order in the HQET. The results were obtained using a sample of 600 quenched gauge field configurations, generated by Monte Carlo simulation at $\beta=6.0$ on a $24^{3}\times 40$ lattice. For the light quarks the SW-Clover action was used; the propagator of the lattice HQET was also tree-level improved. Our best estimate of the renormalization scale independent B-parameter is $\hat{B}_{B_d} = 1.03 \pm 0.06 \pm 0.18$. $\hat{B}_{B_d}$ has been obtained by using ``boosted'' perturbation theory to calculate the renormalization constants which relate the matrix elements of the lattice operators to the corresponding amplitudes in the continuum. Due to the large statistics, the errors in the extraction of the matrix elements of the relevant bare operators are rather small. The main systematic error, corresponding to $\pm 0.18$ in the above result, comes from the uncertainty in the evaluation of the renormalization constants, for which the one-loop corrections are rather large. The non-perturbative evaluation of these constants will help to reduce the final error. We also obtain $\hat{B}_{B_s}/\hat{B}_{B_d} = 1.01 \pm 0.01$ and $f^2_{B_s}\hat{B}_{B_s}/f^2_{B_d}\hat{B}_{B_d} = 1.38 \pm 0.07$.Comment: 15 pages, Latex, 2 figures, Small numerical errors corrected, no conclusions change

Benchmark of the PenRed Monte Carlo framework for HDR brachytherapy

[EN] Purpose: The purpose of this study is to validate the PenRed Monte Carlo framework for clinical applications in brachytherapy. PenRed is a C++ version of Penelope Monte Carlo code with additional tallies and utilities. Methods and materials: Six benchmarking scenarios are explored to validate the use of PenRed and its improved bachytherapy-oriented capabilities for HDR brachytherapy. A new tally allowing the evaluation of collisional kerma for any material using the track length kerma estimator and the possibility to obtain the seed positions, weights and directions processing directly the DICOM file are now implemented in the PenRed distribution. The four non-clinical test cases developed by the Joint AAPM-ESTRO-ABG-ABS WG-DCAB were evaluated by comparing local and global absorbed dose differences with respect to established reference datasets. A prostate and a palliative lung cases, were also studied. For them, absorbed dose ratios, global absorbed dose differences, and cumulative dose-volume histograms were obtained and discussed. Results: The air-kerma strength and the dose rate constant corresponding to the two sources agree with the reference datatests within 0.3% (Sk) and 0.1% (¿). With respect to the first three WG-DCAB test cases, more than 99.8% of the voxels present local (global) differences within ±1%(±0.1%) of the reference datasets. For test Case 4 reference dataset, more than 94.9%(97.5%) of voxels show an agreement within ±1%(±0.1%), better than similar benchmarking calculations in the literature. The track length kerma estimator scorer implemented increases the numerical efficiency of brachytherapy calculations two orders of magnitude, while the specific brachytherapy source allows the user to avoid the use of error-prone intermediate steps to translate the DICOM information into the simulation. In both clinical cases, only minor absorbed dose differences arise in the low-dose isodoses. 99.8% and 100% of the voxels have a global absorbed dose difference ratio within ±0.2% for the prostate and lung cases, respectively. The role played by the different segmentation and composition material in the bone structures was discussed, obtaining negligible absorbed dose differences. Dose-volume histograms were in agreement with the reference data. Conclusions: PenRed incorporates new tallies and utilities and has been validated for its use for detailed and precise high-dose-rate brachytherapy simulations.This work is partially supported by the Ministerio de Ciencia e Innovación of Spain (MCIN) grants PID2020- 113126RB-I00 and PID2021-125096NB-I00 funded by MCIN/AEI/10.13039/501100011033. V. G. acknowledges partial support from AEI-MICINN under grant PID2020-1 13334GB-I00/AEI/10.13039/501100011033 and by Generalitat Valenciana through the project PROMETEO/2019/087. The work has also been supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) grant RGPIN-2019-05038. Francisco Berumen acknowledges support by the Fonds de Recherche du Québec ¿ Nature et Technologies (FRQNT). J.V. and F.B. would like to acknowledge funding by MCIN/ AEI/10.13039 and the Generalitat Valenciana (GVA) grant PROMETEO/2021/064. Our colleague Prof. Vicent Giménez Gómez passed away on November 16, 2022, during the proofs of this study. We dedicate it to his memory. The Universitat de València lost a dedicated and accomplished physicist.Oliver-Gil, S.; Giménez-Alventosa, V.; Berumen, F.; Giménez, V.; Beaulieu, L.; Ballester, F.; Vijande, J. (2023). Benchmark of the PenRed Monte Carlo framework for HDR brachytherapy. Zeitschrift für Medizinische Physik. 33(4):511-528. https://doi.org/10.1016/j.zemedi.2022.11.00251152833

Non-perturbative renormalization of lattice operators in coordinate space

We present the first numerical implementation of a non-perturbative renormalization method for lattice operators, based on the study of correlation functions in coordinate space at short Euclidean distance. The method is applied to compute the renormalization constants of bilinear quark operators for the non-perturbative O(a)-improved Wilson action in the quenched approximation. The matching with perturbative schemes, such as MS-bar, is computed at the next-to-leading order in continuum perturbation theory. A feasibility study of this technique with Neuberger fermions is also presented.Comment: 11 pages and 9 figures, LaTeX2

Matrix Elements without Quark Masses on the Lattice

We introduce a new parameterization of four-fermion matrix elements which does not involve quark masses and thus allows a reduction of systematic uncertainties in physical amplitudes. As a result the apparent quadratic dependence of e'/e on m_s is removed. To simplify the matching between lattice and continuum renormalization schemes, we express our results in terms of Renormalization Group Invariant B-parameters which are renormalization-scheme and scale independent. As an application of our proposal, matrix elements of DeltaI=3/2 and SUSY DeltaF=2 ($F=S,C,B$) four-fermion operators have been computed.Comment: LATTICE99(Matrix Elements), 3 pages, 1 figure, BUHEP-99-2