Large NN scaling and factorization in SU(N)\mathrm{SU}(N) Yang-Mills theory

We present results for Wilson loops smoothed with the Yang-Mills gradient flow and matched through the scale $t_0$. They provide renormalized and precise operators allowing to test the $1/N^2$ scaling both at finite lattice spacing and in the continuum limit. Our results show an excellent scaling up to $1/N = 1/3$. Additionally, we obtain a very precise non-perturbative confirmation of factorization in the large $N$ limit.Comment: 8 pages, 7 figures. Presented at the 35th International Symposium on Lattice Field Theory, Granada, Spain, 18-24 June 2017 (Lattice 2017

A multilevel algorithm for flow observables in gauge theories

We study the possibility of using multilevel algorithms for the computation of correlation functions of gradient flow observables. For each point in the correlation function an approximate flow is defined which depends only on links in a subset of the lattice. Together with a local action this allows for independent updates and consequently a convergence of the Monte Carlo process faster than the inverse square root of the number of measurements. We demonstrate the feasibility of this idea in the correlation functions of the topological charge and the energy density.Comment: Minor modifications to the text. Version accepted to be published in PRD. 18 pages, 5 figure

Large NN scaling and factorization in SU(NN) Yang-Mills gauge theory

The large $N$ limit of SU($N$) gauge theories is well understood in perturbation theory. Also non-perturbative lattice studies have yielded important positive evidence that 't Hooft's predictions are valid. We go far beyond the statistical and systematic precision of previous studies by making use of the Yang-Mills gradient flow and detailed Monte Carlo simulations of SU($N$) pure gauge theories in 4 dimensions. With results for $N=3,4,5,6,8$ we study the limit and the approach to it. We pay particular attention to observables which test the expected factorization in the large $N$ limit. The investigations are carried out both in the continuum limit and at finite lattice spacing. Large $N$ scaling is verified non-perturbatively and with high precision; in particular, factorization is confirmed. For quantities which only probe distances below the typical confinement length scale, the coefficients of the $1/N$ expansion are of $\mathrm{O}(1)$, but we found that large (smoothed) Wilson loops have rather large $\mathrm{O}(1/N^2)$ corrections. The exact size of such corrections does, of course, also depend on what is kept fixed when the limit is taken.Comment: 25 pages, 11 figure

Employment and Unemployment Transitions in Spain from 1996 to 2005

In this paper, we have studied the employment and nonemployment transitions in Spain from 1996 to 2005. To do so, we have used a multi-state multiepisode duration model and a censored continuous-time Markovian matrix. By using the censored Markovian matrix, we have been able to balance the negative effect that censore has on the estimated parameters. The results obtained suggest that women have a probability of employment six percent lower than men. In addition, we have been able to show that Spanish employees experience three different stages of employment during their first decade in the labor market.Employment and Nonemployment Transitions; Multi-state Multi-episode Duration Model; Hazard Rate; Censored Continuous-time Markovian Matrix

Path Integral approach to nonequilibrium potentials in multiplicative Langevin dynamics

We present a path integral formalism to compute potentials for nonequilibrium steady states, reached by a multiplicative stochastic dynamics. We develop a weak-noise expansion, which allows the explicit evaluation of the potential in arbitrary dimensions and for any stochastic prescription. We apply this general formalism to study noise-induced phase transitions. We focus on a class of multiplicative stochastic lattice models and compute the steady state phase diagram in terms of the noise intensity and the lattice coupling. We obtain, under appropriate conditions, an ordered phase induced by noise. By computing entropy production, we show that microscopic irreversibility is a necessary condition to develop noise-induced phase transitions. This property of the nonequilibrium stationary state has no relation with the initial stages of the dynamical evolution, in contrast with previous interpretations, based on the short-time evolution of the order parameter.Comment: 6 pages, 1 figure. Final version accepted for publication in EP

Projectivity of Planar Zeros in Field and String Theory Amplitudes

We study the projective properties of planar zeros of tree-level scattering amplitudes in various theories. Whereas for pure scalar field theories we find that the planar zeros of the five-point amplitude do not enjoy projective invariance, coupling scalars to gauge fields gives rise to tree-level amplitudes whose planar zeros are determined by homogeneous polynomials in the stereographic coordinates labelling the direction of flight of the outgoing particles. In the case of pure gauge theories, this projective structure is generically destroyed if string corrections are taken into account. Scattering amplitudes of two scalars with graviton emission vanish exactly in the planar limit, whereas planar graviton amplitudes are zero for helicity violating configurations. These results are corrected by string effects, computed using the single-valued projection, which render the planar amplitude nonzero. Finally, we discuss how the structure of planar zeros can be derived from the soft limit behavior of the scattering amplitudes.Comment: 39 page, 5 figures. v2: typos corrected. It matches the version published in Journal of High Energy Physic

Absceso hepático que simula un tumor: reporte de un caso pediátrico

A case report of a 3-year-old boy with past medical history of intestinal partially treated amebiasis, is presented. The patient was admitted to Pediatric Unit, San Cristóbal Central Hospi- tal, Táchira, Venezuela, with abdominal pain and fever. An abdominal bloating and a 3 cm palpable hepatomegaly below the right costal margin were assessed. Abdominal ultrasound revealed a liver enlarged in the right antero-superior area. A rounded space-occupying lesion, predominantly solid, with mixed-echo patterns, was assessed using ultrasound. The preliminary diagnosis issued was of acute medical abdomen with hepatic space-occupying lesion considered amebic liver abscess or liver tumor, moderate hypochromic microcytic anemia, and malnutrition with short stature. During the case evolution, a frst computerized tomography exploration was necessary in order to exploit the capacity of this imaging tech- nique to scan an abscess as a peripheral pseudo-capsule showing rim enhancement. Nevertheless, this theoretical shape associated with abscesses on computerized tomog- raphy scans was unable to verify in this study. At this point, the mixed-echo patterns of the preliminary ultrasound study and the imprecision of the computerized tomography scan to categorize the lesion as an abscess or a tumor, do not allow establishing a defnitive diagnosis. A management based on antibiotic therapy is then proposed. The progression of the space-occupying lesion was performed using ultrasound and computerized tomography scans during the clinical evolution. The imaging controls probe a slight decrease of the liver le- sion, which is diagnosed as a liver abscess. Percutaneous transhepatic drainage was performed. An amoebic liver ab- scess in resolution was fnally diagnosed.Se presenta un case clínico de un niño de 3 años con antece- dentes médicos de amebiasis intestinal parcialmente tratada. El paciente ingresó en la Unidad de Pediatría del Hospital Central San Cristóbal, Táchira, Venezuela, con dolor abdomi- nal y febre. Se evaluó un abdomen plano y una hepatomega- lia palpable de 3 cm por debajo del reborde costal derecho. La ecografía abdominal reveló un hígado agrandado en el área anterosuperior derecha. Se evaluó una lesión ocupan- te de espacio redondeado, predominantemente sólida, con patrones de eco mixto, mediante ultrasonido. El diagnóstico preliminar emitido fue de abdomen médico agudo con lesión hepática ocupante de espacio considerada absceso hepático amebiano o tumor hepático, anemia microcítica hipocrómica moderada y desnutrición con talla baja. Durante la evolución del caso, fue necesaria una primera exploración de tomogra- fía computarizada para explotar la capacidad de esta técnica de imagen para escanear un absceso como una pseudocáp- sula periférica que muestra el borde realzado. Sin embar- go, esta forma teórica asociada con abscesos en tomografía computarizada no se pudo verifcar en este estudio. En este punto, los patrones de eco mixto del ultrasonido preliminar y la imprecisión de la tomografía computarizada para clasifcar la lesión como un absceso o un tumor, no permiten estable- cer un diagnóstico defnitivo. Se propone terapia con antibió- ticos. La progresión de la lesión ocupante de espacio se rea- lizó mediante ecografía y tomografía computarizada durante la evolución clínica. Los controles de imágenes refejan una ligera disminución de la lesión hepática, que se diagnostica como un absceso hepático. Se realizó drenaje transhepático percutáneo. Finalmente se diagnosticó un absceso hepático amebiano en resolución