One-loop Higgs boson production at the Linear Collider within the general two-Higgs-doublet model: e+e− versus γγ

present an updated overview on the phenomenology of one-loop Higgs boson production at Linear Colliders within the general Two-Higgs-Doublet Model (2HDM). First we report on the Higgs boson pair production, and associated Higgs-Z boson production, at O(α3ew) from e+e− collisions. These channels furnish cross-sections in the range of 10–100 fb for √s = 0.5TeV and exhibit potentially large radiative corrections (|δr| ∼ 50%), whose origin can be traced back to the genuine enhancement capabilities of the triple Higgs boson self-interactions. Next we consider the loop-induced production of a single Higgs boson from direct γγ scattering. We single out sizable departures from the expected γγ → h rates in the Standard Model, which are again correlated to trademark dynamical features of the 2HDM—namely the balance of the non-standard Higgs/gauge, Higgs/fermion and Higgs self-interactions, which leads to sizable (destructive) interference effects. This pattern of quantum effects is unmatched in the MSSM, and could hence provide distinctive footprints of non-supersymmetric Higgs boson physics. Both calculations are revisited within a common, brought-to-date framework and include, in particular, the most stringent bounds from unitarity and flavor physics

What is there in the black box of dark energy: variable cosmological parameters or multiple (interacting) components?

The coincidence problems and other dynamical features of dark energy are studied in cosmological models with variable cosmological parameters and in models with the composite dark energy. It is found that many of the problems usually considered to be cosmological coincidences can be explained or significantly alleviated in the aforementioned models.Comment: 6 pages, 1 figure, talk given at IRGAC2006 (Barcelona, July 11-15, 2006), to appear in J. Phys.

Dark energy: a quantum fossil from the inflationary Universe?

The discovery of dark energy (DE) as the physical cause for the accelerated expansion of the Universe is the most remarkable experimental finding of modern cosmology. However, it leads to insurmountable theoretical difficulties from the point of view of fundamental physics. Inflation, on the other hand, constitutes another crucial ingredient, which seems necessary to solve other cosmological conundrums and provides the primeval quantum seeds for structure formation. One may wonder if there is any deep relationship between these two paradigms. In this work, we suggest that the existence of the DE in the present Universe could be linked to the quantum field theoretical mechanism that may have triggered primordial inflation in the early Universe. This mechanism, based on quantum conformal symmetry, induces a logarithmic, asymptotically-free, running of the gravitational coupling. If this evolution persists in the present Universe, and if matter is conserved, the general covariance of Einstein's equations demands the existence of dynamical DE in the form of a running cosmological term whose variation follows a power law of the redshift.Comment: LaTeX, 14 pages, extended discussion. References added. Accepted in J. Phys. A: Mathematical and Theoretica

Cosmologies with variable parameters and dynamical cosmon: implications on the cosmic coincidence problem

Dynamical dark energy (DE) has been proposed to explain various aspects of the cosmological constant (CC) problem(s). For example, it is very difficult to accept that a strictly constant Lambda-term constitutes the ultimate explanation for the DE in our Universe. It is also hard to acquiesce in the idea that we accidentally happen to live in an epoch where the CC contributes an energy density value right in the ballpark of the rapidly diluting matter density. It should perhaps be more plausible to conceive that the vacuum energy, is actually a dynamical quantity as the Universe itself. More generally, we could even entertain the possibility that the total DE is in fact a mixture of vacuum energy and other dynamical components (e.g. fields, higher order terms in the effective action etc) which can be represented collectively by an effective entity X (dubbed the ``cosmon''). The ``cosmon'', therefore, acts as a dynamical DE component different from the vacuum energy. While it can actually behave phantom-like by itself, the overall DE fluid may effectively appear as standard quintessence, or even mimic at present an almost exact CC behavior. Thanks to the versatility of such cosmic fluid we can show that a composite DE system of this sort (``LXCDM'') may have a key to resolving the mysterious coincidence problem.Comment: LaTeX, 13 pages, 5 figure

Cosmology with variable parameters and effective equation of state for Dark Energy

A cosmological constant, Lambda, is the most natural candidate to explain the origin of the dark energy (DE) component in the Universe. However, due to experimental evidence that the equation of state (EOS) of the DE could be evolving with time/redshift (including the possibility that it might behave phantom-like near our time) has led theorists to emphasize that there might be a dynamical field (or some suitable combination of them) that could explain the behavior of the DE. While this is of course one possibility, here we show that there is no imperative need to invoke such dynamical fields and that a variable cosmological constant (including perhaps a variable Newton's constant too) may account in a natural way for all these features.Comment: LaTeX, 9 pages, 1 figure. Talk given at the 7th Intern. Workshop on Quantum Field Theory Under the Influence of External Conditions (QFEXT 05

Variabilidad de peso vivo: Efectos sobre el rendimiento y la gestión de los cebaderos porcinos

publishedTomo I . Sección: Sistemas Ganaderos-Economía y Gestión. Sesión: Conejos, abejas, peces y cerdos. Ponencia nº 2

Simulación de procesos con controladores lógico-programables (PLC’s)

La realización de prácticas en el laboratorio de control de procesos presenta como mayor dificultad el coste asociado al funcionamiento del proceso, debido al consumo de reactivos, de energía o a la generación de residuos. Por tanto se propone trabajar con un proceso simulado en un controlador lógico- programable o PLC, con lo que se realiza una práctica de bajo coste y más cercana a la realidad que la pura simulación numérica

Quantum effects on Higgs-strahlung events at Linear Colliders within the general 2HDM

The associated production of neutral Higgs bosons with the Z gauge boson is investigated in the context of the future linear colliders, such as the ILC and CLIC, within the general two-Higgs-doublet model (2HDM). We compute the corresponding production cross-sections at one-loop, in full consistency with the available theoretical and phenomenological constraints. We find that the wave-function renormalization corrections to the external Higgs fields are the dominant source of the quantum effects, which turn out to be large and negative, and located predominantly in the region around \tan\beta=1 and moderate values of the parameter \lambda_5 (being \lambda_5 < 0). This behavior can be ultimately traced back to the enhancement potential of the triple Higgs boson self-couplings, a trademark feature of the 2HDM with no counterpart in the Higgs sector of the Minimal Supersymmetric Standard Model. The predicted Higgs-strahlung rates comfortably reach a few tens of femtobarn, which means barely 10^3 - 10^4 events per 500 inverse femtobarn of integrated luminosity. Due to their great complementarity, we argue that the combined analysis of the Higgs-strahlung events and the previously computed one-loop Higgs-pair production processes could be instrumental to probe the structure of the Higgs sector at future linac facilities.Comment: LaTeX, 16 pages, 9 Figures, 2 Tables. Extended discussion, references added, matches published version in Phys. Rev.

Knee function through finite element analysis and the role of Miocene hominoids in our understanding of the origin of antipronograde behaviours: the Pierolapithecus catalaunicus patella as a case study

Although extensive research has been carried out in recent years on the origin and evolution of human bipedalism, a full understanding of this question is far from settled. Miocene hominoids are key to a better understanding of the locomotor types observed in living apes and humans. Pierolapithecus catalaunicus, an extinct stem great ape from the middle Miocene (c. 12.0 Ma) of the Vallès-Penedès Basin (north-eastern Iberian Peninsula), is the first undoubted hominoid with an orthograde (erect) body plan. Its locomotor repertoire included above-branch quadrupedalism and other antipronograde behaviours. Elucidating the adaptive features present in the Pierolapithecus skeleton and its associated biomechanics helps us to better understand the origin of hominoid orthogrady. This work represents a new biomechanical perspective on Pierolapithecus locomotion, by studying its patella and comparing it with those drawn from a large sample of extant anthropoids. This is the first time that the biomechanical patellar performance in living non-human anthropoids and a stem hominid has been studied using finite element analysis (FEA). Differences in stress distribution are found depending on body plan and the presence/absence of a distal apex, probably due to dissimilar biomechanical performances. Pierolapithecus’ biomechanical response mainly resembles that of great apes, suggesting a similar knee joint use in mechanical terms. These results underpin previous studies on Pierolapithecus, favouring the idea that a relevant degree of some antipronograde behaviour may have made up part of its locomotor repertoire. Moreover, our results corroborate the presence of modern great ape-like knee biomechanical performances back in the Miocene

Cosmological Constant Problems and Renormalization Group

The Cosmological Constant Problem emerges when Quantum Field Theory is applied to the gravitational theory, due to the enormous magnitude of the induced energy of the vacuum. The unique known solution of this problem involves an extremely precise fine-tuning of the vacuum counterpart. We review a few of the existing approaches to this problem based on the account of the quantum (loop) effects and pay special attention to the ones involving the renormalization group.Comment: 12 pages, LaTeX, based on the on the talk at IRGAC-2006 (Barcelona, July 11-15, 2006), misprints corrected, comment on anthropic approach modified, some references added, accepted in Journal of Physics