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A complete, gauge-invariant computation of two loop virtual corrections involving closed fermion loops to the polarized M{\o}ller scattering asymmetry is presented. The set of contributions involving two closed fermion loops and the set…

High Energy Physics - Phenomenology · Physics 2021-04-07 Yong Du , Ayres Freitas , Hiren H. Patel , Michael J. Ramsey-Musolf

Two-loop contributions to the muon (g-2) from fermion/sfermion loops in the MSSM are presented, and an overview of the full MSSM prediction for (g-2) is given with emphasis on the behaviour in scenarios which are compatible with LHC data,…

High Energy Physics - Phenomenology · Physics 2015-06-17 Helvecio Fargnoli , Christoph Gnendiger , Sebastian Passehr , Dominik Stöckinger , Hyejung Stöckinger-Kim

The partition function of two dimensional massless staggered fermions interacting with U(N) gauge fields is rewritten in terms of loop variables in the strong coupling limit. We use this representation of the theory to devise a non-local…

High Energy Physics - Lattice · Physics 2009-11-07 Shailesh Chandrasekharan

We present preliminary result for the study of the renormalization group evolution of tensor bilinears in Schr\"odinger Functional (SF) schemes for $N_f=0$ and $N_f=2$ QCD with non-perturbatively $\mathcal{O}(a)$-improved Wilson fermions.…

High Energy Physics - Lattice · Physics 2015-11-26 Patrick Fritzsch , Carlos Pena , David Preti

We investigate the continuum limit of the rooted staggered action in the 2-dimensional Schwinger model. We match both the unrooted and rooted staggered determinants with an overlap fermion determinant of two (one) flavors and a local pure…

High Energy Physics - Lattice · Physics 2008-11-26 Anna Hasenfratz , Roland Hoffmann

We perform a perturbative calculation of the influence of dynamical HISQ fermions on the perturbative improvement of the gluonic action in the same way as we have previously done for asqtad fermions. We find the fermionic contributions to…

High Energy Physics - Lattice · Physics 2009-06-09 A. Hart , G. M. von Hippel , R. R. Horgan

We present preliminary results for $\epsilon'/\epsilon$ calculated using HYP staggered fermions in the quenched approximation. We compare different choices of quenched penguin operators.

High Energy Physics - Lattice · Physics 2008-11-26 Tanmoy Bhattacharya , George T. Fleming , Rajan Gupta , Greg Kilcup , Weonjong Lee , Stephen Sharpe

The coefficient $c_{\rm sw}$ appearing in the Sheikholeslami-Wohlert improved action is computed to one loop perturbation theory for improved gluon actions including six-link loops. The O($a$) improvement coefficients for the dimension…

High Energy Physics - Lattice · Physics 2009-10-31 Sinya Aoki , Roberto Frezzotti , Peter Weisz

Linear and non-linear QCD evolutions at high energy suffer from severe issues related to convergence, due to higher order corrections enhanced by large double and single transverse logarithms. We resum double logarithms to all orders by…

High Energy Physics - Phenomenology · Physics 2015-09-29 E. Iancu , J. D. Madrigal , A. H. Mueller , G. Soyez , D. N. Triantafyllopoulos

A new formulation of chiral fermions on the lattice is presented. It is a version of overlap fermions, but built from the computationally efficient staggered fermions rather than the previously used Wilson fermions. The construction reduces…

High Energy Physics - Lattice · Physics 2011-05-18 David H. Adams

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

The Fat Link Irrelevant Clover (FLIC) fermion action is a variant of the $O(a)$-improved Wilson action where the irrelevant operators are constructed using smeared links. While the use of such smearing allows for the use of highly improved…

High Energy Physics - Lattice · Physics 2008-11-26 Waseem Kamleh , Ben Lasscock , Derek B. Leinweber , Anthony G. Williams

We have investigated a system with two sets of staggered fermions with charges 1 and -1/2 coupling to a non-compact U(1) gauge field in 4 dimensions. The model exhibits breaking of chiral symmetries of both fermions at different values of…

High Energy Physics - Lattice · Physics 2009-10-22 Arifa Ali Khan

We discuss the improvement of flavour non-singlet point and one-link lattice quark operators, which describe the quark currents and the first moment of the DIS structure functions respectively. Suitable bases of improved operators are…

High Energy Physics - Lattice · Physics 2008-11-26 S. Capitani , M. Goeckeler , R. Horsley , H. Perlt , P. E. L. Rakow , G. Schierholz , A. Schiller

We present recent results from lattice simulations of 2+1 flavors of improved staggered fermions at zero baryon number density near the high temperature crossover. Included are new results from simulations of asqtad fermions at Nt = 12 and…

High Energy Physics - Lattice · Physics 2011-01-27 Wolfgang Söldner

A compact general integral formula is derived from which the fermionic contribution to the one-loop coefficient in the perturbative expansion of the MSbar coupling in powers of the bare lattice coupling can be extracted. It is seen to…

High Energy Physics - Lattice · Physics 2008-11-26 David H. Adams

We derive bases of improved operators for all bilinear quark currents up to spin two (including the operators measuring the first moment of DIS Structure Functions), and compute their one-loop renormalization constants for arbitrary…

High Energy Physics - Lattice · Physics 2008-11-26 S. Capitani , M. Goeckeler , R. Horsley , H. Perlt , P. Rakow , G. Schierholz , A. Schiller

We present and test a new method for simulating dynamical fermions with fat links. Our construction is based on the introduction of auxiliary but dynamical gauge fields and works with any fermionic action and can be combined with any…

High Energy Physics - Lattice · Physics 2009-10-31 F. Knechtli , A. Hasenfratz

We present a semi-numerical algorithm to calculate one-loop virtual corrections to scattering amplitudes. The divergences of the loop amplitudes are regulated using dimensional regularization. We treat in detail the case of amplitudes with…

High Energy Physics - Phenomenology · Physics 2008-11-26 R. K. Ellis , W. T. Giele , G. Zanderighi

Smeared link fermionic actions can be straightforwardly simulated with partial-global updating. The efficiency of this simulation is greatly increased if the fermionic matrix is written as a product of several near-identical terms. Such a…

High Energy Physics - Lattice · Physics 2009-11-07 Andrei Alexandru , Anna Hasenfratz