Non-perturbative renormalization of tensor currents: strategy and results for Nf= 0 and Nf= 2 QCD: ALPHA Collaboration

Tensor currents are the only quark bilinear operators lacking a non-perturbative determination of their renormalisation group (RG) running between hadronic and electroweak scales. We develop the setup to carry out the computation in lattice QCD via standard recursive finite-size scaling techniques, and provide results for the RG running of tensor currents in Nf= 0 and Nf= 2 QCD in the continuum for various Schrödinger Functional schemes. The matching factors between bare and renormalisation group invariant currents are also determined for a range of values of the lattice spacing relevant for large-volume simulations, thus enabling a fully non-perturbative renormalization of physical amplitudes mediated by tensor current

FLAG review 2019: Flavour lattice Averaging Group (FLAG)

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UA

Large Nc scaling of meson masses and decay constants

We perform an ab initio calculation of the Nc scaling of the low-energy couplings of the chiral Lagrangian of low-energy strong interactions, extracted from the mass dependence of meson masses and decay constants. We compute these observables on the lattice with four degenerate fermions, Nf= 4 , and varying number of colours, Nc= 3 –6, at a lattice spacing of a≃ 0.075 fm. We find good agreement with the expected Nc scaling and measure the coefficients of the leading and subleading terms in the large Nc expansion. From the subleading Nc corrections, we can also infer the Nf dependence, that we use to extract the value of the low-energy couplings for different values of Nf. We find agreement with previous determinations at Nc= 3 and Nf= 2 , 3 and also, our results support a strong paramagnetic suppression of the chiral condensate in moving from Nf= 2 to Nf=

FLAG Review 2021

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, los autores pertenecientes a la UAM y el nombre del grupo de colaboración, si lo hubiereWe review lattice results related to pion, kaon, D-meson, B-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More specifically, we report on the determination of the light-quark masses, the form factor f+(0) arising in the semileptonic K→ π transition at zero momentum transfer, as well as the decay constant ratio fK/ fπ and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2) L× SU(2) R and SU(3) L× SU(3) R Chiral Perturbation Theory. We review the determination of the BK parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. For the heavy-quark sector, we provide results for mc and mb as well as those for the decay constants, form factors, and mixing parameters of charmed and bottom mesons and baryons. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. We review the status of lattice determinations of the strong coupling constant αs. We consider nucleon matrix elements, and review the determinations of the axial, scalar and tensor bilinears, both isovector and flavor diagonal. Finally, in this review we have added a new section reviewing determinations of scale-setting quantitie

A comparison of Wilson and twisted mass valence quarks for charmed semileptonic form factors

39th International Symposium on Lattice Field Theory, LATTICE 2022 Bonn 8 August 2022 through 13 August 2022 Code 187776We present two calculations of heavy quark physics, with respectively non-perturbatively improved Wilson and twisted mass Wilson fermions, both on Nf = 2 + 1 CLS configurations with open boundary conditions. We evaluate those discretisations through a Ward identity on the three-point functions. We also check the universality of our continuum results. All our results are compatible with an O (a2) scaling for both action

Non-perturbative quark mass renormalisation and running in Nf = 3 QCD

We determine from first principles the quark mass anomalous dimension in Nf= 3 QCD between the electroweak and hadronic scales. This allows for a fully non-perturbative connection of the perturbative and non-perturbative regimes of the Standard Model in the hadronic sector. The computation is carried out to high accuracy, employing massless O(a)-improved Wilson quarks and finite-size scaling techniques. We also provide the matching factors required in the renormalisation of light quark masses from lattice computations with O(a)-improved Wilson fermions and a tree-level Symanzik improved gauge action. The total uncertainty due to renormalisation and running in the determination of light quark masses in the SM is thus reduced to about 1

Towards precision charm physics with a mixed action

39th International Symposium on Lattice Field Theory, LATTICE 2022 Bonn 8 August 2022 through 13 August 2022 Code 187776We report on our first set of results for charm physics, using a mixed-action setup with maximally twisted valence fermions on CLS Nf = 2+1 ensembles. This setup avoids the need of improvement coefficients to subtract O (amc) effects. The charm quark mass, D and Ds decay constants are computed on a subset of CLS ensembles, which allows to take the continuum limit and extrapolate to the physical pion mass, and assess the scaling properties. Special attention is paid to the implementation of techniques to deal with systematic uncertainties. Our results show excellent prospects for high-precision computations on the full set of ensemblesWe acknowledge PRACE and RES for giving us access to computational resources at MareNostrum (BSC). We thank CESGA for granting access to Finis Terrae II. This work is supported by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 813942 and by the Spanish MINECO through project PGC2018-094857-B-I00, the Centro de Excelencia Severo Ochoa Programme through SEV-2016-0597 and the Ramón y Cajal Programme RYC-2012-024

Nuevas aplicaciones de la regularización reticular al estudio de teorías Gauge

Tesis doctoral inédita leida en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica. Fecha de lectura: 23-06-200