32nd International Symposium on Lattice Field Theory (Lattice 2014)

Session

Standard model parameters and renormalization

8

24 Jun 2014, 14:15

Columbia University

Conveners

Standard model parameters and renormalization: Parallel 3G

• Georg von Hippel (University of Mainz)

Standard model parameters and renormalization: Parallel 4G

• Tanmoy Bhattacharya (Los Alamos National Laboratory)

Standard model parameters and renormalization: Parallel 7G

• Christopher Monahan (College of William and Mary)

Standard model parameters and renormalization: Parallel 9E

• Gunnar Bali (University of Regensburg)

237. A perturbative study of the chirally rotated Schrödinger functional in QCD

Dr Pol Vilaseca Mainar (Instituto Nazionale di FIsica Nucleare)

24/06/2014, 14:15

Standard Model Parameters and Renormalization

Talk

The chirally rotated Schrödinger functional renders the mechanism of automatic O(a) improvement compatible with the Schrödinger functional (SF) formulation. We here report on the determination to 1-loop order in perturbation theory of the renormalization coefficients necessary to achieve automatic O(a) improvement and the boundary improvement coefficients needed to eliminate the extra...

159. A dynamical study of the chirally rotated Schrödinger functional in QCD

Mr Mattia Dalla Brida (Trinity College Dublin)

24/06/2014, 14:35

Standard Model Parameters and Renormalization

Talk

The chirally rotated Schrödinger functional for Wilson quarks allows for finite-volume, mass-independent renormalization schemes compatible with automatic O(a)-improvement. So far, in QCD, the setup has only been studied in the quenched approximation. Here we present first results for Nf=2 dynamical flavors for several renormalization factors of quark bilinears. We discuss how such...

284. Non perturbative renormalization and running of Delta F=2 four-fermion operators in the SF scheme.

Dr Mauro Papinutto (Universita "La Sapienza" and INFN Sez. di Roma)

24/06/2014, 14:55

Standard Model Parameters and Renormalization

Talk

We present preliminary results of a non-perturbative study of the scale-dependent renormalization constants of a complete basis of Delta F=2 parity-odd four-fermion operators that enter the computation of hadronic B-parameters within the SM and beyond. We consider non-perturbatively O(a) improved Wilson fermions and our gauge configurations contain two flavors of massless sea quarks. The...

331. Non-perturbative improvement of the axial current in N_f=3 lattice QCD

Dr Jochen Heitger (University of Muenster)

24/06/2014, 15:15

Standard Model Parameters and Renormalization

Talk

We present the results of a non-perturbative determination of the improvement coefficient c_A of the axial vector current in three-flavour lattice QCD with O(a) improved Wilson quarks and tree-level Symanzik improved gauge action. Our computation involves an improvement condition which is imposed at a constant physical volume of about 1.2 fm and employs the PCAC relation in the Schrödinger...

333. Non-perturbative renormalization of the axial current in N_f=3 lattice QCD

Mr Christian Wittemeier (Westfälische Wilhelms-Universität Münster)

24/06/2014, 15:35

Standard Model Parameters and Renormalization

Talk

We report on a non-perturbative computation of the renormalization factor Z_A of the axial vector current in three-flavour O(a) improved lattice QCD with Wilson quarks and tree-level Symanzik improved gauge action. Our normalization condition is formulated at constant physics in the same Schrödinger functional setup as is being used for the determination of the improvement coefficient c_A. It...

180. Renormalization constants for $N_{\mathrm{f}}=2+1+1$ twisted mass QCD

Dr Savvas Zafeiropoulos (LPC Universite Blaise Pascal CNRS)

24/06/2014, 16:30

Standard Model Parameters and Renormalization

Talk

We summarize recent non-perturbative results obtained for renormalization constants computed in the RI’-MOM scheme for $N_{\mathrm{f}}=2+1+1$ twisted mass QCD. Our implementation employs the Iwasaki gauge action and four dynamical degenerate twisted mass fermions. Renormalization constants for scalar, pseudo-scalar, vector and axial operators, as well as for the quark propagator, are computed at...

344. NPR step-scaling across the charm threshold

Dr Julien Frison (University of Edinburgh)

24/06/2014, 16:50

Standard Model Parameters and Renormalization

Talk

While Non-Perturbative Renormalisation by itself can be done at any scale, converting it to a perturbative scheme introduces a systematic error decreasing with the scale. In the case of the B_K four quark operator, this is now the dominant error on the MSbar result at 3 GeV. Increasing this scale requires both the access to finer lattices and a correct treatment of the charm effects. We will...

210. Non-perturbative Renormalization of Four-fermion Operators Relevant to B_K with Staggered Quarks.

Mr Jangho Kim (Seoul National University)

24/06/2014, 17:10

Standard Model Parameters and Renormalization

Talk

We present matching factors for the four-fermion operators obtained using the non-perturbative renormalization method (NPR) in RI-MOM scheme for improved staggered fermions on the MILC asqtad lattice (N_f = 2+1). Using 20^3 * 64 lattice (a = 0.12 fm, am_l/am_s = 0.01/0.05), we obtain the matching factor of B_K operator. Also we are in the middle of data analysis on the BSM...

216. Nonperturbative renormalization of bilinear operators with Mobius domain-wall fermions in the coordinate space

Mr Masaaki Tomii (Graduate university for advanced studies)

24/06/2014, 17:30

Standard Model Parameters and Renormalization

Talk

We study a non-perturbative determination of the renormalization constants of flavor non-singlet quark bilinear operators. The renormalization condition is imposed on correlation functions of bilinear operators in the coordinate space. The results are converted to the value in the MSbar scheme by a perturbative matching. The calculation is done on gauge configurations generated with the Mobius...

286. Physical and cut-off effects of heavy charm-like sea quarks

Prof. Francesco Knechtli (University of Wuppertal)

24/06/2014, 17:50

Standard Model Parameters and Renormalization

Talk

We simulate a theory with two dynamical O(a) improved Wilson quarks whose mass M is close the charm quark mass and at three values of the lattice spacing ranging from 0.066 to 0.038 fm. This theory is a prototype to study the decoupling of heavy quarks. We measure the mass and cut-off dependence of ratios of gluonic observables defined from the Wilson flow or the static potential. The...

280. Towards a new determination of the QCD Lambda parameter from running couplings in the three-flavour theory

Dr Patrick Fritzsch (Humboldt University Berlin)

26/06/2014, 14:15

Standard Model Parameters and Renormalization

Talk

We review our new strategy and current status towards a high precision computation of the Lambda parameter from three-flavour simulations in QCD. To reach this goal we combine specific advantages of the Schroedinger functional and gradient flow couplings.

152. A Feynman-Hellmann approach to nonperturbative renormalization of lattice operators

Dr Holger Perlt (Leipzig university)

26/06/2014, 14:35

Standard Model Parameters and Renormalization

Talk

Renormalization factors are needed to related lattice quantities to their corresponding continuum counterparts. In order to renormalize singlet observables one has to include connected and disconnected diagrams. Especially, the disconnected contributions are very difficult to calculate using the standard three-point function technique. The Feynman-Hellmann method provides the possibility to...

268. Determination of \(c_{\rm sw}\) in \(N_f=3+1\) Lattice QCD with massive Wilson fermions

Felix Stollenwerk (Humboldt University Berlin)

26/06/2014, 14:55

Standard Model Parameters and Renormalization

Talk

We develop a strategy for the non-perturbative determination of the O(\(a\))-improvement coefficient \(c_{\rm sw}\) for Wilson fermions with massive sea quarks. The improvement condition is defined via the PCAC relation in the Schrödinger functional. It is imposed along a line of constant physics designed to be close to the correct mass of the charm quark. The numerical work uses the...

222. Using NSPT for the Removal of Hypercubic Lattice Artifacts

Mr Jakob Simeth (University of Regensburg)

27/06/2014, 16:30

Standard Model Parameters and Renormalization

Talk

The quantification and subtraction of hypercubic lattice artifacts is essential for the calculation of non-perturbative renormalization constants. It has been shown that for the RI'-MOM scheme a large part of these artifacts can be calculated using Lattice Perturbation Theory (LPT), but these calculations are typically restricted to 1-loop order and to bilinear quark operators with one...

425. An update on the status of NSPT computations

Dr Michele Brambilla (Università di Parma and INFN)

27/06/2014, 16:50

Standard Model Parameters and Renormalization

Talk

In recent years Numerical Stochastic Perturbation Theory (NSPT) has proven to be a viable tool to perform perturbative computation at high order on the lattice. Despite final results are equivalent to standard Feynman diagrams the approach is rather different and allows a numerical implementation similar to usual (nonperturbative) MonteCarlo. I will discuss final results for the computation...

154. Calculating the glue helicity on the lattice with comments about renormalization

Dr Michael Glatzmaier (University of Kentucky)

27/06/2014, 17:10

Standard Model Parameters and Renormalization

Talk

We discuss recent preliminary results for a lattice calculation of the glue helicity ${\mathrm{\Delta }}_G$ in the Coulomb gauge. We have used the gauge field tensor defined from the overlap Dirac operator. The calculation is carried out with valence overlap quarks on 2+1 DWF gauge configurations on the ${24}^3\times 64$ lattice which corresponds to a pion mass of 330 MeV. Finally, we discuss the...

295. Isospin Effects by Mass Reweighting

Mr Jacob Finkenrath (University of Wuppertal)

27/06/2014, 17:30

Standard Model Parameters and Renormalization

Talk

Most of today's lattice simulations are performed in the isospin symmetric limit in the light quark sector. A technique with moderate numerical cost to include effects of isospin breaking in the sea quark sector is mass reweighting. We will give a summary of the recent results on fine lattices with light quark masses. In general reweighting corrects the weight of an ensemble which is...

366. Renormalization of Flavor Singlet and Nonsinglet Fermion Bilinear Operators

Prof. Haralambos (Haris) Panagopoulos (Univeristy of Cyprus)

27/06/2014, 17:50

Standard Model Parameters and Renormalization

Talk

We compute the difference in the renormalization of flavor singlet and nonsinglet fermion bilinear operators, to 2 loops in perturbation theory. Our results are applicable to a rather wide class of lattice actions with Symanzik improved gluons, stout links and clover fermions, including the Twisted Mass and SLiNC actions.