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We propose a continuous real space renormalization group transformation based on gradient flow, allowing for a numerical study of renormalization without the need for costly ensemble matching. We apply our technique in a pilot study of…

High Energy Physics - Lattice · Physics 2018-11-19 Andrea Carosso , Anna Hasenfratz , Ethan T. Neil

We present a two-loop computation of the beta functions and the anomalous dimensions of a $\gamma_5$-Yukawa model using differential renormalization. The calculation is carried out in coordinate space without modifying the space-time…

High Energy Physics - Theory · Physics 2009-10-22 Cristina Manuel

Renormalization constants of vector ($Z_V$) and axial-vector ($Z_A$) currents are determined non-perturbatively in quenched QCD for a renormalization group improved gauge action and a tadpole improved clover quark action using the…

We present results concerning the non-perturbative evaluation of the renormalisation constant for the quark field, $Z_q$, from lattice simulations with twisted mass quarks and three values of the lattice spacing. We use the RI'-MOM scheme.…

High Energy Physics - Phenomenology · Physics 2011-05-05 B. Blossier , Ph. Boucaud , M. Brinet , F. De Soto , Z. Liu , V. Morenas , O. Pène , K. Petrov , J. Rodríguez-Quintero

We apply the method of graphical functions that was recently extended to six dimensions for scalar theories, to $\phi^3$ theory and compute the $\beta$ function, the wave function anomalous dimension as well as the mass anomalous dimension…

High Energy Physics - Theory · Physics 2021-07-07 M. Borinsky , J. A. Gracey , M. V. Kompaniets , O. Schnetz

QCD perturbation theory using quark and gluon propagators that have an extra term at zero four-momentum is equivalent to standard PQCD in the presence of massless quark and gluon pairs in the perturbative vacuum. We verify at low orders in…

High Energy Physics - Phenomenology · Physics 2009-11-07 Paul Hoyer

We present a non-perturbative determination of the renormalization factor Z_S of the scalar density in quenched QCD with overlap fermions. Results are obtained at four values of the lattice spacing. By combining Z_S with results for the…

High Energy Physics - Lattice · Physics 2009-11-11 Jan Wennekers , Hartmut Wittig

We calculate perturbative renormalization constants for the \Delta B=2 four-quark operators in lattice NRQCD. Continuum operators \bar{b}\gamma_{\mu}(1-\gamma_5)q~ \bar{b}\gamma_{\mu}(1-\gamma_5)q and…

High Energy Physics - Lattice · Physics 2009-10-31 S. Hashimoto , K-I. Ishikawa , T. Onogi , M. Sakamoto , N. Tsutsui , N. Yamada

Using non-perturbative techniques we have found the renormalisation factor, Z, in the RI-MOM scheme for quark bilinear operators in quenched QCD. We worked with overlap fermions using the Luescher-Weisz gauge action. Our calculation was…

High Energy Physics - Lattice · Physics 2016-09-01 M. Gürtler , R. Horsley , P. E. L. Rakow , C. J. Roberts , G. Schierholz , T. Streuer

We present results of a quenched QCD simulation with overlap fermions on a lattice of volume V = 16^3X32 at beta=6.0, which corresponds approximatively to a lattice cutoff of 2 GeV and an extension of 1.4 fm. From the two-point correlation…

High Energy Physics - Lattice · Physics 2015-06-25 L. Giusti , C. Hoelbling , C. Rebbi

The renormalization of the scalar diquark operator and its anomalous dimension is calculated at two-loop order in QCD, enabling higher-order QCD studies of diquarks. As an application of our result, the two-loop diquark anomalous dimension…

High Energy Physics - Phenomenology · Physics 2011-11-30 R. T. Kleiv , T. G. Steele

By considering the scaling behaviour of various Feynman graphs at leading order in large $\Nf$ at the non-trivial fixed point of the $d$-dimensional $\beta$-function of QCD we deduce the critical exponents corresponding to the quark, gluon…

High Energy Physics - Theory · Physics 2009-10-22 J. A. Gracey

We present results on the two-loop anomalous dimensions of the heavy baryon HQET currents $J=(q^TC\Gamma\tau q)\Gamma'Q$ with arbitrary Dirac matrices $\Gamma$ and $\Gamma'$. From our general result we obtain the two-loop anomalous…

High Energy Physics - Phenomenology · Physics 2009-10-28 S. Groote , J. G. Körner , O. I. Yakovlev

We evaluate the complete four-loop anomalous dimension matrix that is necessary for determining the effective flavour-changing neutral current couplings qbar-q'-gamma and qbar-q'-g at the next-to-next-to-leading order in QCD. The resulting…

High Energy Physics - Phenomenology · Physics 2010-10-27 Michal Czakon , Ulrich Haisch , Mikolaj Misiak

We report results of quark masses in quenched lattice QCD with the Kogut-Susskind fermion action, employing the Reguralization Independent scheme (RI) of Martinelli et al. to non-perturbatively evaluate the renormalization factor relating…

We comment on the recent attempt by M. Franz et al [1] to further justify their earlier calculation of the gauge-invariant electron propagator in the context of the QED_3 theory of the pseudogap phase in cuprates [2]. First, we use the…

Strongly Correlated Electrons · Physics 2007-05-23 D. V. Khveshchenko

Numerical Stochastic Perturbation Theory was able to get three- (and even four-) loop results for finite Lattice QCD renormalization constants. More recently, a conceptual and technical framework has been devised to tame finite size…

High Energy Physics - Lattice · Physics 2015-06-17 Michele Brambilla , Francesco Di Renzo

Three-loop counterterms for the Standard Model (SM) revealed that the matrix of anomalous dimensions ($\gamma$) of quarks is divergent in the $d \to 4$ limit unless a carefully chosen non-Hermitian square-root of $Z$ matrix is used in the…

High Energy Physics - Phenomenology · Physics 2021-10-04 Adrian Lewandowski

Dimensional Reduction is applied to \qcd{} in order to compute various renormalization constants in the \drbar{} scheme at higher orders in perturbation theory. In particular, the $\beta$ function and the anomalous dimension of the quark…

High Energy Physics - Phenomenology · Physics 2009-11-11 R. Harlander , P. Kant , L. Mihaila , M. Steinhauser

We extend the recent one loop analysis of the ultraviolet completion of the $CP(N)$ nonlinear $\sigma$ model in six dimensions to two loop order in the MSbar scheme for an arbitrary covariant gauge. In particular we compute the anomalous…

High Energy Physics - Theory · Physics 2020-08-26 J. A. Gracey