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Isabel Campos

Publications and source records attributed to Isabel Campos.

31 records · Page 2Linked to original sources
arXiv2018

Controlling quark mass determinations non-perturbatively in three-flavour QCD

The determination of quark masses from lattice QCD simulations requires a non-perturbative renormalization procedure and subsequent scale evolution to high energies, where a conversion to the commonly used MS-bar scheme can be safely established. We present our results for the non-perturbative running of renormalized quark masses in Nf=3 QCD between the electroweak and a hadronic energy scale, where lattice simulations are at our disposal. Recent theoretical advances in combination with well-established techniques allows to follow the scale evolution to very high statistical accuracy, and full control of systematic effects.

hep-lat↗
arXiv2018

Non-perturbative quark mass renormalisation and running in $N_f=3$ 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%.

hep-lat↗
arXiv2018

Enabling rootless Linux Containers in multi-user environments: the udocker tool

Containers are increasingly used as means to distribute and run Linux services and applications. In this paper we describe the architectural design and implementation of udocker, a tool which enables the user to execute Linux containers in user mode. We also present a few practical applications, using a range of scientific codes characterized by different requirements: from single core execution to MPI parallel execution and execution on GPGPUs.

cs.SE↗
arXiv2017

openQ*D simulation code for QCD+QED

The openQ*D code for the simulation of QCD+QED with C$^\star$ boundary conditions is presented. This code is based on openQCD-1.6, from which it inherits the core features that ensure its efficiency: the locally-deflated SAP-preconditioned GCR solver, the twisted-mass frequency splitting of the fermion action, the multilevel integrator, the 4th order OMF integrator, the SSE/AVX intrinsics, etc. The photon field is treated as fully dynamical and C$^\star$ boundary conditions can be chosen in the spatial directions. We discuss the main features of openQ*D, and we show basic test results and performance analysis. An alpha version of this code is publicly available and can be downloaded from http://rcstar.web.cern.ch/ .

hep-lat↗
arXiv2016

Non-perturbative running of quark masses in three-flavour QCD

We present our preliminary results for the computation of the non-perturbative running of renormalized quark masses in $N_f = 3$ QCD, between the electroweak and hadronic scales, using standard finite-size scaling techniques. The computation is carried out to very high precision, using massless $\mathcal{O}(a)$-improved Wilson quarks. Following the strategy adopted by the ALPHA Collaboration for the running coupling, different schemes are used above and below a scale $μ_0 \sim m_b$, which differ by using either the Schrödinger Functional or Gradient Flow renormalized coupling. We discuss our results for the running in both regions, and the procedure to match the two schemes.

hep-lat↗
arXiv2001

Monte Carlo study of the magnetic properties of the 3D Hubbard model

We investigate numerically the magnetic properties of the 3D Isotropic and Anisotropic Hubbard model at half-filling. The behavior of the transition temperature as a function of the anisotropic hopping parameter is qualitatively described. In the Isotropic model we measure the scaling properties of the susceptibility finding agreement with the magnetic critical exponents of the 3D Heisenberg model. We also describe several particularities concerning the implementation of our simulation in a cluster of personal computers.

cond-mat.str-el↗
arXiv2000

Global Anomalies in chiral gauge theories on the lattice

We discuss the issue of global anomalies in chiral gauge theories on the lattice. In Luscher's approach, these obstructions make it impossible to define consistently a fermionic measure for the path integral. We show that an SU(2) theory has such a global anomaly if the Weyl fermion is in the fundamental representation. The anomaly in higher representations is also discussed. We finally show that this obstruction is the lattice analogue of the SU(2) anomaly first discovered by Witten.

hep-lat↗
arXiv1999

Global anomalies in Chiral Lattice Gauge Theory

As first realized by Witten an SU(2) gauge theory coupled to a single Weyl fermion suffers from a global anomaly. This problem is addressed here in the context of the recent developments on chiral gauge theories on the lattice. We find Witten's anomaly manifests in the impossibility of defining globally a fermion measure that reproduces the proper continuum limit. Moreover, following Witten's original argument, we check numerically the crossing of the lowest eigenvalues of Neuberger's operator along a path connecting two gauge fields that differ by a topologically non-trivial gauge transformation.

hep-lat↗
arXiv1998

The U(1) phase transition on toroidal and spherical lattices

We have studied the properties of the phase transition in the U(1) compact pure gauge model paying special atention to the influence of the topology of the boundary conditions. From the behavior of the energy cumulants and the observation of an effective ν-> 1/d on toroidal and spherical lattices, we conclude that the transition is first order.

hep-lat↗
arXiv1998

A study of the phase transition in 4D pure compact U(1) LGT on toroidal and spherical lattices

We have performed a systematic study of the phase transition in the pure compact U(1) lattice gauge theory in the extended coupling parameter space (β, γ) on toroidal and spherical lattices. The observation of a non-zero latent heat in both topologies for all investigated γin the interval [+0.2,-0.4], together with an effective exponent ν= 1/d when large enough lattices are considered, lead us to conclude that the phase transition is first order. For negative γ, our results point to an increasingly weak first order transition as γis made more negative.

hep-lat↗
arXiv1997

On the SU(2)-Higgs Phase Transition

The properties of the Confinement-Higgs phase transition in the SU(2)-Higgs model with fixed modulus are investigated. We show that the system exhibits a transient behavior up to L=24 along which the order of the phase transition cannot be discerned. To get stronger conclusions about this point, without going to prohibitive large lattice sizes, we have introduced a second (next-to-nearest neighbors) gauge-Higgs coupling, k2. On this extended parameter space we find a line of phase transitions which become increasely weaker as k2 tends to 0. The results point to a first order character for the transition with the standard action (k2 = 0).

hep-lat↗
arXiv1996

Antiferromagnetic 4-d O(4) Model

We study the phase diagram of the four dimensional O(4) model with first (beta1) and second (beta2) neighbor couplings, specially in the beta2 < 0 region, where we find a line of transitions which seems to be second order. We also compute the critical exponents on this line at the point beta1 =0 (F4 lattice) by Finite Size Scaling techniques up to a lattice size of 24, being these exponents different from the Mean Field ones.

hep-lat↗