Numerical Evaluation of Six-Photon Amplitudes

We apply the recently proposed amplitude reduction at the integrand level method, to the computation of the scattering process 2 photons -> 4 photons, including the case of a massive fermion loop. We also present several improvements of the method, including a general strategy to reconstruct the rational part of any one-loop amplitude and the treatment of vanishing Gram-determinants.Comment: 21 pages, 3 figures. Version accepted for publication in JHE

Top quark pair production in association with a jet with NLO parton showering

We compute the production cross section of a top-antitop pair in association with a jet at hadron colliders at next-to-leading order accuracy matched with parton shower algorithms to make predictions at the hadron level. The parton shower allows for including the decay of the top quarks at the leading order accuracy. We use a framework based on three well established numerical codes, the POWHEG-BOX, used for the calculation of the cross section, HELAC, which generates the matrix elements for the Born-level, real emission and the virtual part, and finally a parton shower program, such as PYTHIA or HERWIG, which generate the parton-shower and hadronization.Comment: changed title, bug in HERWIG analysis corrected, published version with restructured discussion, but main conclusions unchange

On the Rational Terms of the one-loop amplitudes

The various sources of Rational Terms contributing to the one-loop amplitudes are critically discussed. We show that the terms originating from the generic (n-4)-dimensional structure of the numerator of the one-loop amplitude can be derived by using appropriate Feynman rules within a tree-like computation. For the terms that originate from the reduction of the 4-dimensional part of the numerator, we present two different strategies and explicit algorithms to compute them.Comment: 14 pages, 3 figures, uses axodraw.st

CutTools: a program implementing the OPP reduction method to compute one-loop amplitudes

We present a program that implements the OPP reduction method to extract the coefficients of the one-loop scalar integrals from a user defined (sub)-amplitude or Feynman Diagram, as well as the rational terms coming from the 4-dimensional part of the numerator. The rational pieces coming from the epsilon-dimensional part of the numerator are treated as an external input, and can be computed with the help of dedicated tree-level like Feynman rules. Possible numerical instabilities are dealt with the help of arbitrary precision routines, that activate only when needed.Comment: Version published in JHE

Development and reliability of questionnaires for the assessment of diet and physical activity behaviors in a multi-country sample in Europe the Feel4Diabetes Study

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Complete off-shell effects in top quark pair hadroproduction with leptonic decay at next-to-leading order

Results for next-to-leading order QCD corrections to the pp(p\bar{p}) -> t \bar{t} -> W^+W^- b\bar{b} -> e^{+} \nu_{e} \mu^{-} \bar{\nu}_{\mu} b \bar{b} +X processes with complete off-shell effects are presented for the first time. Double-, single- and non-resonant top contributions of the order {\cal{O}}(\alpha_{s}^3 \alpha^4) are consistently taken into account, which requires the introduction of a complex-mass scheme for unstable top quarks. Moreover, the intermediate W bosons are treated off-shell. Comparison to the narrow width approximation for top quarks, where non-factorizable corrections are not accounted for is performed. Besides the total cross section and its scale dependence, several differential distributions at the TeVatron run II and the LHC are given. In case of the TeVatron the forward-backward asymmetry of the top is recalculated afresh. With inclusive selection cuts, the forward-backward asymmetry amounts to A^{t}_{FB} = 0.051 +/- 0.0013. Furthermore, the corrections with respect to leading order are positive and of the order 2.3% for the TeVatron and 47% for the LHC. A study of the scale dependence of our NLO predictions indicates that the residual theoretical uncertainty due to higher order corrections is 8% for the TeVatron and 9% for the LHC.Comment: 35 pages, 39 figures, 3 tables. References and note added, version to appear in JHE

Conducta suicida no letal en Castellón: un estudio descriptivo y comparativo.

Treball Final de Grau en Medicina. Codi: MD1158. Curs acadèmic: 2018/2019.Background: Due to the suicidal behavior variability regarding the sociocultural values of each territory, we conducted this study to define the sociodemographic and clinical features of the patients from Castellon. The objective is to obtain deeper knowledge that facilitate the detection and implementation of effective interventions. In addition, we carried out a comparative analysis between non-lethal suicide cases (our sample) and completed suicide cases. Methods: Our sample includes every person assisted for non-lethal suicidal behavior in the Psychiatric Emergency room at Castellon’s Provincial Hospital from January 19th to February 15th, performing an 8 year follow-up. Our completed suicide sample was taken from a previous study conducted in 2018.2 Results: Our sample showed an average age of 39, with a majority of women (56.1%) and psychiatric pathology diagnosis (74.2%, mainly anxiety-depressive disorders). Most of them were being followed by a health service (81.2%, generally their GP). The most frequent suicide method was drug overdose (94.4%). After the suicide episode, only 27 patients (40.9%) attended the healthcare service they were referred to, what may explain the persistance of the suicidal behavior during the follow-up (7.7% suicidal threats and 34.5% attempts) Conclusions: Non-lethal suicidal behavior in Castellon is more frequent among young, women, and those with psychiatric disorders, using as main suicidal method drug overdose. Most of them don’t attend the health care service responsible for their follow-up. Moreover, it was found that the completed suicide profile differs from the non-lethal; it is therefore required to develop different therapeutical and preventive strategies for each one.Introducción: Dada la variabilidad en la conducta suicida según los valores socioculturales de cada territorio, realizamos este estudio para definir las características sociodemográficas y clínicas de los pacientes con comportamiento suicida no letal de nuestra provincia. Pretendemos ampliar nuestro conocimiento para facilitar la detección de individuos en riesgo e implantar intervenciones efectivas. Además, realizamos una comparativa entre las características de nuestra muestra con las de suicidio consumado. Material y métodos: La muestra incluye toda conducta suicida no letal registrada en el Hospital Provincial de Castellón entre el 19 de enero y 15 de febrero de 2009, realizándose un seguimiento hasta febrero de 2017. La muestra de suicidio consumado es tomada de un proyecto previo de 2018. Resultados: La muestra la integran mayormente individuos jóvenes (media de 39 años), de sexo femenino (56.1%), con patología psiquiátrica (74.2%, principalmente trastornos ansioso-depresivos) y en seguimiento sanitario (81.2%, predominantemente MAP (77.3%)). El método de suicidio más frecuente fue la sobreingesta medicamentosa (94.4%). Sólo 27 pacientes (40.9%) acudieron tras el episodio a los servicios de salud remitidos, facilitándose así la persistencia de la conducta durante el seguimiento (7.7% amenazas, 34.5% tentativas). Conclusiones: La conducta suicida no letal de Castellón predomina entre adultos jóvenes, de sexo femenino, con trastornos psiquiátricos, que recurren como método a la sobredosis medicamentosa e incumplen el seguimiento a posteriori. Además, se comprobó que el perfil del comportamiento suicida letal difiere de los rasgos de la conducta suicida no letal, evidenciando la necesidad de desarrollar estrategias preventivas y terapéuticas distintas entre ellos

Counting to one: reducibility of one- and two-loop amplitudes at the integrand level

Calculation of amplitudes in perturbative quantum field theory involve large loop integrals. The complexity of those integrals, in combination with the large number of Feynman diagrams, make the calculations very difficult. Reduction methods proved to be very helpful, lowering the number of integrals that need to be actually calculated. Especially, the reduction at the integrand level technique, improves the speed and set-up of these calculations. In this article we demonstrate, by counting the numbers of tensor structures and independent coefficients, how to write such relations at the integrand level for one- and two-loop amplitudes. We clarify their connection to the so-called spurious terms at one loop and discuss their structure in the two-loop case. This method is also applicable to higher loops, and the results obtained apply to both planar and non-planar diagrams

Phosphoglycerate dehydrogenase diverts glycolytic flux and contributes to oncogenesis

Most tumors exhibit increased glucose metabolism to lactate, however, the extent to which glucose-derived metabolic fluxes are used for alternative processes is poorly understood [1, 2]. Using a metabolomics approach with isotope labeling, we found that in some cancer cells a relatively large amount of glycolytic carbon is diverted into serine and glycine metabolism through phosphoglycerate dehydrogenase (PHGDH). An analysis of human cancers showed that PHGDH is recurrently amplified in a genomic region of focal copy number gain most commonly found in melanoma. Decreasing PHGDH expression impaired proliferation in amplified cell lines. Increased expression was also associated with breast cancer subtypes, and ectopic expression of PHGDH in mammary epithelial cells disrupted acinar morphogenesis and induced other phenotypic alterations that may predispose cells to transformation. Our findings show that the diversion of glycolytic flux into a specific alternate pathway can be selected during tumor development and may contribute to the pathogenesis of human cancer.National Institutes of Health (U.S.)National Cancer Institute (U.S.)Smith Family FoundationDamon Runyon Cancer Research FoundationBurroughs Wellcome Fun