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In this paper, we consider the Group Lasso estimator of the covariance matrix of a stochastic process corrupted by an additive noise. We propose to estimate the covariance matrix in a high-dimensional setting under the assumption that the…

Statistics Theory · Mathematics 2011-10-26 Jérémie Bigot , Rolando Biscay , Jean-Michel Loubes , Lilian Muniz Alvarez

Lattice gauge fixing is required to compute gauge-variant quantities, for example those used in RI-MOM renormalization schemes or as objects of comparison for model calculations. Recently, gauge-variant quantities have also been found to be…

High Energy Physics - Lattice · Physics 2024-10-07 William Detmold , Gurtej Kanwar , Yin Lin , Phiala E. Shanahan , Michael L. Wagman

We review our perturbative techniques for improved heavy quark actions. A new procedure for computing improvement coefficients is suggested, where the continuum limit of a lattice-regularized theory provides the matching conditions.We also…

High Energy Physics - Lattice · Physics 2009-11-10 Matthew Nobes , Howard Trottier

The study of nuclear physics using lattice QCD is hindered by an exponentially large signal-to-noise problem which is conventionally alleviated by raising the quark masses to unphysically high values. We propose a novel form of partial…

High Energy Physics - Lattice · Physics 2010-01-12 Amy N. Nicholson

We determine to order alpha^3 in the quenched approximation the so-called residual mass in the lattice regularisation of the Heavy Quark Effective Theory. We follow a gauge-invariant strategy which exploits the fact that this mass term…

High Energy Physics - Lattice · Physics 2010-02-03 F. Di Renzo , L. Scorzato

We explore a novel approach to compute the force between a static quark and a static antiquark with lattice gauge theory directly. The approach is based on expectation values of Wilson loops or Polyakov loops with chromoelectric field…

High Energy Physics - Lattice · Physics 2022-04-06 Nora Brambilla , Viljami Leino , Owe Philipsen , Christian Reisinger , Antonio Vairo , Marc Wagner

Re-weighting is a useful tool that has been employed in Lattice QCD in different contexts including, tuning the strange quark mass, approaching the light quark mass regime, and simulating electromagnetic fields on top of QCD gauge…

High Energy Physics - Lattice · Physics 2011-12-20 Abdou Abdel-Rehim , William Detmold , Kostas Orginos

A general class of loop quantizations for anisotropic models is introduced and discussed, which enhances loop quantum cosmology by relevant features seen in inhomogeneous situations. The main new effect is an underlying lattice which is…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald , Daniel Cartin , Gaurav Khanna

We consider robust covariance estimation with group symmetry constraints. Non-Gaussian covariance estimation, e.g., Tyler scatter estimator and Multivariate Generalized Gaussian distribution methods, usually involve non-convex minimization…

Machine Learning · Statistics 2013-06-19 Ilya Soloveychik , Ami Wiesel

Bayesian inference for high-dimensional inverse problems is computationally costly and requires selecting a suitable prior distribution. Amortized variational inference addresses these challenges via a neural network that approximates the…

Machine Learning · Statistics 2023-01-19 Ali Siahkoohi , Gabrio Rizzuti , Rafael Orozco , Felix J. Herrmann

In this paper, a shrinkage estimator for the population mean is proposed under known quadratic loss functions with unknown covariance matrices. The new estimator is non-parametric in the sense that it does not assume a specific parametric…

Methodology · Statistics 2014-11-07 Cheng Wang , Tiejun Tong , Longbing Cao , Baiqi Miao

We describe a stochastic technique which allows one to compute numerically the coefficients of the weak coupling perturbative expansion of any observable in Lattice Gauge Theory. The idea is to insert the exponential representation of the…

High Energy Physics - Lattice · Physics 2009-10-22 F. Di Renzo , G. Marchesini , P. Marenzoni , E. Onofri

In this work we investigate theoretical and computational aspects of novel lattice fermion formulations for the simulation of lattice gauge theories. The lattice approach to quantum gauge theories is an important tool for studying quantum…

High Energy Physics - Lattice · Physics 2017-03-21 Christian Zielinski

Building upon recent developments of force-based estimators with a reduced variance for the computation of densities, radial distribution functions or local transport properties from molecular simulations, we show that the variance can be…

Chemical Physics · Physics 2021-05-18 Samuel W. Coles , Etienne Mangaud , Daan Frenkel , Benjamin Rotenberg

We present a quenched lattice calculation of low energy constants using the chirally improved Dirac operator. Several lattice sizes at different lattice spacings are studied. We systematically compare various methods for computing these…

High Energy Physics - Lattice · Physics 2008-11-26 Christof Gattringer , Philipp Huber , C. B. Lang

Variational approximation methods have proven to be useful for scaling Bayesian computations to large data sets and highly parametrized models. Applying variational methods involves solving an optimization problem, and recent research in…

Methodology · Statistics 2017-01-13 Victor M. -H. Ong , David J. Nott , Michael S. Smith

In this paper will be presented methodology of encoding information in valuations of discrete lattice with some translational invariant constrains in asymptotically optimal way. The method is based on finding statistical description of such…

Information Theory · Computer Science 2008-11-02 Jarek Duda

Shrinkage can effectively improve the condition number and accuracy of covariance matrix estimation, especially for low-sample-support applications with the number of training samples smaller than the dimensionality. This paper investigates…

Information Theory · Computer Science 2018-10-22 Jun Tong , Rui Hu , Jiangtao Xi , Zhitao Xiao , Qinghua Guo , Yanguang Yu

Analyzing high-dimensional data with manifold learning algorithms often requires searching for the nearest neighbors of all observations. This presents a computational bottleneck in statistical manifold learning when observations of…

Machine Learning · Computer Science 2022-03-11 Fan Cheng , Anastasios Panagiotelis , Rob J Hyndman

We propose to estimate the weight matrix used for forecast reconciliation as parameters in a general linear model in order to quantify its uncertainty. This implies that forecast reconciliation can be formulated as an orthogonal projection…

Methodology · Statistics 2024-02-12 Jan Kloppenborg Møller , Peter Nystrup , Poul G. Hjorth , Henrik Madsen
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