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Can dark energy be expressed as a power series of the Hubble parameter?Apr 30 2019May 02 2019In this work we examine the possibility that the dark energy (DE) density, $\rho_{de}$ can be dynamical and appear as a power series expansion of the Hubble rate (and its derivatives), i.e.$\rho_{de}(H,\dot{H},...)$. For the present universe, however, ... More

Cosmological constant and vacuum energy: old and new ideasJun 06 2013Jul 21 2013The cosmological constant (CC) term in Einstein's equations, Lambda, was first associated to the idea of vacuum energy density. Notwithstanding, it is well-known that there is a huge, in fact appalling, discrepancy between the theoretical prediction and ... More

The Top-Quark Width in the Light of $Z$-Boson PhysicsAug 21 1995Aug 30 1995We discuss possible non-standard contributions to the top-quark width, particularly the virtual effects on the standard decay $t\rightarrow W^+\,b$ within the context of the MSSM. We also place a renewed emphasis on the unconventional mode $t\rightarrow ... More

Brans-Dicke gravity: from Higgs physics to (dynamical) dark energyMay 24 2018Oct 31 2018The Higgs mechanism is one of the central pieces of the Standard Model of electroweak interactions and thanks to it we can generate the masses of the elementary particles. Its fundamental origin is nonetheless unknown. Furthermore, in order to preserve ... More

Cosmologies with a time dependent vacuumFeb 09 2011The idea that the cosmological term, Lambda, should be a time dependent quantity in cosmology is a most natural one. It is difficult to conceive an expanding universe with a strictly constant vacuum energy density, namely one that has remained immutable ... More

Vacuum energy and cosmological evolutionFeb 27 2014Mar 03 2014An expanding universe is not expected to have a static vacuum energy density. The so-called cosmological constant $\Lambda$ should be an approximation, certainly a good one for a fraction of a Hubble time, but it is most likely a temporary description ... More

Dynamical dark energy: scalar fields and running vacuumOct 27 2016Recent analyses in the literature suggest that the concordance $\Lambda$CDM model with rigid cosmological term, $\Lambda=$const., may not be the best description of the cosmic acceleration. The class of "running vacuum models", in which $\Lambda=\Lambda(H)$ ... More

'Steckbrief' LambdaJan 12 2001Jan 14 2001The phenomenology of the FLRW models with non-vanishing cosmological constant (CC) is briefly surveyed in the light of the recent astrophysical and cosmological observations. A subset of these models, which probably includes the world where we live, is ... More

Looking for quantum SUSY signatures in top quark decays at hadron collidersAug 29 1997Sep 01 1997We discuss the supersymmetric quantum effects on top quark decays within the MSSM. It turns out that t-> H+ b is the most promising candidate for carrying large quantum SUSY signatures. As a result, the recent (tan(beta) M_H) exclusion plots presented ... More

Cosmological constant vis-a-vis dynamical vacuum: bold challenging the $Λ$CDMDec 07 2016Next year we will celebrate 100 years of the cosmological term, $\Lambda$, in Einstein's gravitational field equations, also 50 years since the cosmological constant problem was first formulated by Zeldovich, and almost about two decades of the observational ... More

Supersymmetric Quantum Effects on the hadronic width of a heavy charged Higgs boson in the MSSMDec 22 1997We discuss the QCD and leading electroweak corrections to the hadronic width of the charged Higgs boson of the MSSM. In our renormalization framework, tan(beta) is defined through Gamma(H^+ -> tau^+ nu_{tau}). We show that a measurement of the hadronic ... More

Top and Higgs decays: looking for quantum SUSY signatures in hadron collidersFeb 21 1997Mar 14 1997I present an updated discussion of the one-loop corrections to the standard top quark decay, t-> W^+ b, and to the charged Higgs mode, t-> H^+ b, within the framework of the MSSM. These higher order contributions to the top width are compared with the ... More

The $H_0$ tension in light of vacuum dynamics in the UniverseMay 18 2017Sep 21 2017Despite the outstanding achievements of modern cosmology, the classical dispute on the precise value of $H_0$, which is the first ever parameter of modern cosmology and one of the prime parameters in the field, still goes on and on after over half a century ... More

Quantum SUSY signatures in low and high energy processesJul 03 1998In the search for phenomenological evidence of supersymmetry through the indirect method of quantum signatures, it is useful to seek correlations of the non-standard quantum effects in low and high energy proceses, such as those involving on one hand ... More

The cosmological constant and entropy problems: mysteries of the present with profound roots in the pastMay 21 2015Oct 27 2015An accelerated universe should naturally have a vacuum energy density determined by its dynamical curvature. The cosmological constant is most likely a temporary description of a dynamical variable that has been drastically evolving from the early inflationary ... More

Running Vacuum in the Universe: current phenomenological statusJan 07 2016Jan 13 2016I review the excellent phenomenological status of a class of dynamical vacuum models in which the vacuum energy density, $\rho_{\Lambda}=\rho_{\Lambda}(H)$, as a function of the Hubble rate, evolves through its interaction with dark matter and/or through ... More

Dark matter, dark energy and the time evolution of masses in the UniverseAug 19 2014Sep 03 2014The traditional "explanation" for the observed acceleration of the universe is the existence of a positive cosmological constant. However, this can hardly be a truly convincing explanation, as an expanding universe is not expected to have a static vacuum ... More

t --> W+ b and t --> H+ b at the quantum level in the MSSMFeb 19 1998We compare the standard top quark decay and the charged Higgs decay of the top quark, t --> W+ b and t --> H+ b, at the quantum level in the MSSM. While the SUSY loop corrections to the standard top quark decay are only of a few percent, it turns out ... More

Signs of Interacting Vacuum and Dark Matter in the UniverseApr 25 2019We consider the impact of dynamical dark energy (DDE) in the possible solution of the existing tensions in the $\Lambda$CDM. We test both interacting and non-interacting DE models with dark matter (DM). Among the former, the running vacuum model (RVM) ... More

MSSM and Z width: implications on top quark and Higgs physicsMay 14 1996We discuss the one-loop quantum corrections to the top quark width and to the hadronic widths of the Higgs bosons of the MSSM, and emphasize the results obtained in particular regions of the MSSM parameter space which have been proposed to alleviate the ... More

Cosmology with running parametersDec 05 2005The experimental evidence that the equation of state (EOS) of the dark energy (DE) could be evolving with time/redshift (including the possibility that it might behave phantom-like near our time) suggests that there might be dynamical DE fields that could ... More

Dark energy: a quantum fossil from the inflationary Universe?Oct 22 2007Feb 06 2008The 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 ... More

Matter Non-conservation in the Universe and Dynamical Dark EnergyFeb 23 2012Aug 30 2012In an expanding universe the vacuum energy density \rho_{\Lambda} is expected to be a dynamical quantity. In quantum field theory in curved space-time \rho_{\Lambda} should exhibit a slow evolution, determined by the expansion rate of the universe H. ... More

THE QUANTUM CORRELATION R_b-R_c IN THE MSSM: MORE HINTS OF SUPERSYMMETRY?Feb 16 1995We study the correlation of quantum effects on the ratios R_b and R_c within the framework of the MSSM. While in the SM the quantity R_b is in discrepancy with experiment at the 2 \sigma level from below, and R_c differs from the experimental result at ... More

Supersymmetric three-body decays of the Top Quark in the MSSMMar 29 1996Apr 17 1996We survey all possible supersymmetric three-body decays of the top quark in the framework of the MSSM and present detailed numerical analyses of the most relevant cases. Although the two-body channels are generally dominant, it is not inconceivable that ... More

On the scaling behavior of the cosmological constant and the possible existence of new forces and new light degrees of freedomOct 25 1999Nov 09 1999A large value of the cosmological constant (CC) is induced in the Standard Model (SM) of Elementary Particle Physics because of Spontaneous Symmetry Breaking. To provide a small value of the observable CC one has to introduce the vacuum term which cancels ... More

Implications on the Supersymmetric Higgs sector from Top quark decays at the TevatronJul 31 1997Oct 07 1997From the tau-lepton analysis of the charged Higgs decay of the top quark at the Tevatron, t -> H+ b -> tau+ nu_{tau} b, it is possible to set rather stringent bounds on the (tan(beta),M_{H+})-plane, if one assumes that H+ is a charged member of a generic ... More

Cosmology with variable parameters and effective equation of state for Dark EnergyJan 04 2006A 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 ... More

Matching the Low and High Energy Determinations of $α_s(M_z)$ in the MSSMMay 19 1995Jun 08 1995Recent calculations of supersymmetric corrections to the conflicting ratios $R_b$ and $R_c$ have shown that an alleged discrepancy between the SM predictions of these observables and the corresponding experimental values can be cured in the MSSM within ... More

FCNC top quark decay in the MSSM: a door to SUSY physics in high luminosity colliders?Jun 07 1999Jun 15 1999We study the FCNC top quark decays t -> c h in the framework of the MSSM, where h= h^0,H^0,A^0 is any of the supersymmetric neutral Higgs bosons. We include the leading set of SUSY-QCD and SUSY electroweak contributions. While the FCNC top quark decay ... More

Entropic-force dark energy reconsideredFeb 26 2014May 21 2014We reconsider the entropic-force model in which both kind of Hubble terms ${\dot H}$ and $H^{2}$ appear in the effective dark energy (DE) density affecting the evolution of the main cosmological functions, namely the scale factor, deceleration parameter, ... More

Top quark decays into neutral Higgs bosons and gluon in the MSSMSep 24 1999Flavour changing neutral decays of the top quark are know to be extremely suppressed in the SM. This is especially so for the top quark decay into the SM Higgs boson, whose rate is less than 10^-13. However, it turns out that the decay modes t->c h, with ... More

Effective equation of state for dark energy: mimicking quintessence and phantom energy through a variable LambdaMay 06 2005Aug 20 2005While there is mounting evidence in all fronts of experimental cosmology for a non-vanishing dark energy component in the Universe, we are still far away from understanding its ultimate nature. A fundamental cosmological constant, Lambda, is the most ... More

Dynamical dark energy or variable cosmological parameters?Jul 05 2005Dec 21 2005One of the main aims in the next generation of precision cosmology experiments will be an accurate determination of the equation of state (EOS) for the dark energy (DE). If the latter is dynamical, the resulting barotropic index \omega should exhibit ... More

Quantum Haplodynamics, Dark Matter and Dark EnergyFeb 17 2014Aug 04 2014In quantum haplodynamics (QHD) the weak bosons, quarks and leptons are bound states of fundamental constituents, denoted as haplons. The confinement scale of the associated gauge group SU(2)_h is of the order of $\Lambda_h\simeq 0.3$ TeV. One scalar state ... More

Fundamental constants and cosmic vacuum: the micro and macro connectionFeb 05 2015Mar 26 2015The idea that the vacuum energy density $\rho_{\Lambda}$ could be time dependent is a most reasonable one in the expanding Universe; in fact, much more reasonable than just a rigid cosmological constant for the entire cosmic history. Being $\rho_{\Lambda}=\rho_{\Lambda}(t)$ ... More

Effective equation of state for running vacuum: "mirage" quintessence and phantom dark energyJul 17 2013Nov 04 2013Past analyses of the equation of state (EoS) of the Dark Energy (DE) were not incompatible with a phantom phase near our time. This has been the case in the years of WMAP observations, in combination with the remaining cosmological observables. Such situation ... More

One-loop Higgs boson production at the Linear Collider within the general two-Higgs-doublet model: e+e- versus gamma-gammaJul 07 2011We 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, ... More

On the possible running of the cosmological "constant"Oct 26 2009Despite the many outstanding cosmological observations leading to a strong evidence for a nonvanishing cosmological constant (CC) term in the gravitational field equations, the theoretical status of this quantity seems to be lagging well behind the observational ... More

Cosmological constant, renormalization group and Planck scale physicsMay 25 2003Starting from generic quantum effects at the Planck scale M_P, we find that the renormalization group running of the cosmological constant (CC) at low energies is possible if there is a smooth decoupling of all massive particles from M_P to the mass of ... More

Relaxing the $σ_8$-tension through running vacuum in the UniverseNov 02 2017Jan 08 2018It has recently been shown that the class of running vacuum models (RVMs) has the capacity to fit the overall cosmological observations better than the concordance $\Lambda$CDM model, therefore supporting the possibility of dynamical dark energy (DE). ... More

A Friedmann-Lemaitre-Robertson-Walker cosmological model with running LambdaJan 03 2004Jan 25 2004The idea of a variable dark energy has been entertained many times in the literature and from many different points of view. Quintessence is just a popular way to implement this idea in recent times, but so far with little success. Another possibility ... More

Supersymmetric QCD corrections to the top quark decay of a heavy charged higgs bosonNov 10 1995Oct 24 1996The supersymmetric QCD corrections to the hadronic width of a heavy charged Higgs boson, basically dominated by the top-quark decay mode $H^{+}\rightarrow t \bar{b}$, are evaluated at ${\cal O}(\alpha_s)$ within the MSSM and compared with the standard ... More

Massive fields temper anomaly-induced inflation: the clue to graceful exit?Apr 18 2001Feb 11 2002A method of calculating the vacuum effective action for massive quantum fields in curved space-time is outlined. Our approach is based on the conformal representation of the fields action and on the integration of the corresponding conformal anomaly. ... More

Can the cosmological "constant" run? - It may runAug 03 2008Oct 04 2008Using standard quantum field theory, we discuss several theoretical aspects of the possible running of the cosmological constant (CC) term in Einstein's equations. The basic motivation for the present work is to emphasize that this possibility should ... More

Cosmological Constant Problems and Renormalization GroupNov 08 2006Jan 05 2007The 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 ... More

The $\barΛCDM$ cosmology: from inflation to dark energy through running $Λ$Jan 15 2015Perhaps the deepest mystery of our accelerating Universe in expansion is the existence of a tiny and rigid cosmological constant, $\Lambda$. Its size is many orders of magnitude below the expected one in the standard model of particle physics. However, ... More

Neutral Higgs-pair Production at one-loop from a Generic 2HDMJan 04 2010We present a one-loop analysis of the pairwise production of neutral Higgs bosons (h0A0, H0A0) at linear colliders, such as the ILC and CLIC, within the general Two-Higgs-Doublet Model (2HDM). We single out sizable radiative corrections, which can well ... More

A modified Starobinsky's model of inflation: Anomaly-induced inflation, SUSY and graceful exitOct 24 2002Oct 30 2002We present a model of inflation based on the anomaly-induced effective action of gravity in the presence of a conformally invariant Hilbert-Einstein term. Our approach is based on the conformal representation of the fields action and on the integration ... More

Single Higgs-boson production at a photon-photon collider: general 2HDM versus MSSMJun 16 2011Aug 25 2011We revisit the production of a single Higgs boson from direct \gamma \gamma -scattering at a photon collider. We compute the total cross section \sigma(\gamma \gamma \to h) (for h=h0, H0, A0), and the strength of the effective g_{h \gamma \gamma} coupling ... More

Neutral Higgs-pair production at Linear Colliders within the general 2HDM: quantum effects and triple Higgs boson self-interactionsAug 20 2009Jan 08 2010The pairwise production of neutral Higgs bosons is analyzed in the context of the future linear colliders, such as the ILC and CLIC, within the general Two-Higgs-Doublet Model (2HDM). The corresponding cross-sections are computed at the one-loop level ... More

The scaling evolution of cosmological constantDec 22 2000Feb 26 2002In quantum field theory the parameters of the vacuum action are subject to renormalization group running. In particular, the ``cosmological constant'' is not a constant in a quantum field theory context, still less should be zero. In this paper we continue ... More

Vacuum models with a linear and a quadratic term in H: structure formation and number counts analysisDec 11 2014Jan 29 2015We focus on the class of cosmological models with a time-evolving vacuum energy density of the form $\rho_\Lambda=C_0+C_1 H+C_2 H^2$, where $H$ is the Hubble rate. Higher powers of $H$ could be important for the early inflationary epoch, but are irrelevant ... More

Higgs boson production at Linear Colliders from a generic 2HDM: the role of triple Higgs self-interactionsApr 09 2012We review selected results for Higgs boson production at Linear Colliders in the framework of the general Two-Higgs-Doublet Model (2HDM). We concentrate on the analysis of i) the pairwise production of neutral Higgs bosons (hA,HA); and ii) the neutral ... More

Delta r in the Two-Higgs-Doublet Model at full one loop level -- and beyondNov 01 2012Apr 01 2013After the recent discovery of a Higgs-like boson particle at the CERN LHC-collider, it becomes more necessary than ever to prepare ourselves for identifying its standard or non-standard nature. The Electroweak parameter Delta r relating the values of ... More

Confronting the relaxation mechanism for a large cosmological constant with observationsSep 22 2011Jan 03 2012In order to deal with a large cosmological constant a relaxation mechanism based on modified gravity has been proposed recently. By virtue of this mechanism the effect of the vacuum energy density of a given quantum field/string theory (no matter how ... More

Dynamical vacuum energy in the expanding Universe confronted with observations: a dedicated studySep 24 2014Nov 27 2014Despite the many efforts, our theoretical understanding of the ultimate nature of the dark energy component of the universe still lags well behind the astounding experimental evidence achieved from the increasingly sophisticated observational tools at ... More

Single top-quark production by strong and electroweak supersymmetric flavor-changing interactions at the LHCOct 02 2007Dec 10 2007(Abridged) We report on a complete study of the single top-quark production by direct supersymmetric flavor-changing neutral-current (FCNC) processes at the LHC. The total cross section for pp(gg)->t\bar{c}+\bar{t}c is computed at the 1-loop order within ... More

Full one-loop corrections to sfermion decaysOct 08 2002We analyze the partial decay widths of sfermions decaying into charginos and neutralinos \Gamma(\sfermion -> f'\chi) at the one-loop level. We present the renormalization framework, and discuss the value of the corrections for top- and bottom-squark decays. ... More

Dynamically avoiding fine-tuning the cosmological constant: the "Relaxed Universe"Jun 20 2010Dec 28 2010We demonstrate that there exists a large class of action functionals of the scalar curvature and of the Gauss-Bonnet invariant which are able to relax dynamically a large cosmological constant (CC), whatever it be its starting value in the early universe. ... More

Single Higgs-boson production through gamma-gamma scattering within the general 2HDMMar 28 2009May 07 2009The production of a single neutral Higgs boson h through (loop-induced) gamma-gamma collisions is explored in the context of the linear colliders within the general Two-Higgs-Doublet Model (2HDM). Two different mechanisms are analyzed: on the one hand, ... More

Composite dark energy: cosmon models with running cosmological term and gravitational couplingSep 20 2006Dec 16 2006In the recent literature on dark energy (DE) model building we have learnt that cosmologies with variable cosmological parameters can mimic more traditional DE pictures exclusively based on scalar fields (e.g. quintessence and phantom). In a previous ... More

Electroweak radiative corrections to sfermion decaysJul 01 2003We analyze the partial decay widths of sfermions decaying into charginos and neutralinos $\Gamma(\tilde{f} -> f'\chi)$ at the one-loop level, including the electroweak and strong corrections. We present the renormalization framework, and discuss the value ... More

Higgs potential from extended Brans-Dicke theory and the time-evolution of the fundamental constantsSep 01 2016Nov 30 2016Despite the enormous significance of the Higgs potential in the context of the Standard Model of electroweak interactions and in Grand Unified Theories, its ultimate origin is fundamentally unknown and must be introduced by hand in accordance with the ... More

Higgs potential from extended Brans-Dicke theory and the time-evolution of the fundamental constantsSep 01 2016Despite the enormous significance of the Higgs potential in the context of the Standard Model of electroweak interactions and in Grand Unified Theories, its ultimate origin is fundamentally unknown and must be introduced by hand in accordance with the ... More

Higgs Boson Flavor-Changing Neutral Decays into Top Quark in a General Two-Higgs-Doublet ModelJul 10 2003Oct 03 2003Higgs boson decays mediated by flavor changing neutral currents (FCNC) are very much suppressed in the Standard Model, at the level of 10^{-15} for Higgs boson masses of a few hundred GeV. Therefore, any experimental vestige of them would immediately ... More

Full electroweak one-loop radiative corrections to squark decays in the MSSMJan 09 2001Jan 18 2001We present results on the full one-loop electroweak radiative corrections to the squark decay partial widths into charginos and neutralinos. We show the renormalization framework, and present numerical results for the third squark family. The corrections ... More

Yukawa-coupling corrections to scalar quark decaysFeb 16 1998Aug 01 1998Heavy squark decays into top and charginos or neutralinos could be an unexpected source of top quarks at hadron colliders. A detailed treatment of these processes is necessary for a reliable calculation of both the top quark production cross-section and ... More

Production of single top-quark final states at the LHC from supersymmetric FCNC interactionsJan 16 2008We discuss the production of single top-quark final states by direct supersymmetric flavor-changing interactions at the LHC. The total cross section pp(gg)->t\bar{c}+\bar{t}c is computed at the 1-loop order within the unconstrained MSSM. We prove that ... More

What is there in the black box of dark energy: variable cosmological parameters or multiple (interacting) components?Jan 08 2007The 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 ... More

Generalizing the running vacuum energy model and comparing with the entropic-force modelsApr 21 2012Jul 19 2012We generalize the previously proposed running vacuum energy model by including a term proportional to \dot{H}, in addition to the existing H^2 term. We show that the added degree of freedom is very constrained if both low redshift and high redshift data ... More

Fermionic decays of sfermions: a complete discussion at one-loop orderJul 31 2002Dec 03 2002We present a definition of an on-shell renormalization scheme for the sfermion and chargino-neutralino sector of the Minimal Supersymmetric Standard Model (MSSM). Then, apply this renormalization framework to the interaction between charginos/neutralinos ... More

Quantum effects on Higgs-strahlung events at Linear Colliders within the general 2HDMMar 23 2010Jun 24 2010The 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 ... More

SUSY Higgs boson flavor-changing neutral currents at the LHCJan 23 2006Jan 30 2006We compute and analyze the Flavor-Changing Neutral Current (FCNC) interactions of Minimal Supersymmetric Standard Model Higgs bosons (h = h0, H0, A0) with heavy quarks (top and bottom), focusing on the strongly-interacting sector. We correlate the Higgs ... More

Relaxing a large cosmological constant in the astrophysical domainMay 05 2011Oct 06 2011We study the problem of relaxing a large cosmological constant in the astrophysical domain through a dynamical mechanism based on a modified action of gravity previously considered by us at the cosmological level. We solve the model in the Schwarzschild-de ... More

Relaxing a large cosmological constantFeb 13 2009Jul 23 2009The cosmological constant (CC) problem is the biggest enigma of theoretical physics ever. In recent times, it has been rephrased as the dark energy problem in order to encompass a wider spectrum of possibilities. It is, in any case, a polyhedric puzzle ... More

Scalar Field Theory Description of the Running Vacuum Model: from the scalaron to the "vacuumon"Jan 20 2019Jan 23 2019We investigate the running vacuum model (RVM) in the framework of scalar field theory.This dynamical vacuum model provides an elegant global explanation of the cosmic history, namely the universe starts from a non-singular initial de Sitter vacuum stage, ... More

Brans-Dicke cosmology mimicking running vacuumSep 06 2018Nov 03 2018Brans-Dicke (BD) cosmology is reconsidered from an approach in which the model can be formulated in $\Lambda$CDM form, but at the expense of replacing the rigid cosmological constant $\Lambda$ with a dynamical quasivacuum component which depends on a ... More

Quantum Anomalies, Running Vacuum and Leptogenesis: an InterplayMay 14 2019We discuss a connection between gravitational-wave physics, quantum theory anomalies, right-handed (sterile) neutrinos, (spontaneous) CPT Violation and Leptogenesis, within the framework of string-inspired cosmological models. In particular, we present ... More

Running vacuum in the Universe and the time variation of the fundamental constants of NatureMay 19 2016May 30 2016We compute the time variation of the fundamental constants (such as the ratio of the proton mass to the electron mass, the strong coupling constant, the fine structure constant and Newton's constant) within the context of the so-called running vacuum ... More

Supersymmetric QCD Corrections to the Charged Higgs Boson Decay of the Top QuarkJul 31 1995The one-loop supersymmetric QCD quantum effects on the width of the unconventional top quark decay mode $t\rightarrow H^{+}\, b$ are evaluated within the MSSM. The study of this process is useful to hint at the supersymmetric nature of the charged Higgs ... More

Supersymmetric effects on heavy charged Higgs boson production in hadron collidersOct 17 2002The production of a heavy supersymmetric charged Higgs boson (M_{H^{\pm}}> 200 GeV) at the Tevatron and at the LHC is studied. We include the leading one-loop quantum effects within the MSSM in the relevant high \tan\beta region. Whereas the chances for ... More

Fermionic decays of sfermions in the MSSM: a full one-loop calculationOct 08 2002We present a full one-loop calculation of the electroweak corrections to the partial decay widths of the fermionic modes of sfermions \Gamma(\sfermion \to f'\chi). The main technical points of the renormalization are presented, and the main features of ... More

FCNC top quark decays beyond the Standard ModelJan 26 2001Flavor Changing Neutral Current decays of the top quark within the strict context of the Standard Model are known to be extremely rare. In fact, they are hopelessly undetectable at the Tevatron, LHC and LC in any of their scheduled upgradings. Therefore, ... More

Radiative corrections to top quark decay into charged Higgs at the TevatronMar 01 1999We present the computation of the leading one-loop electroweak radiative corrections to the non-standard top quark decay width Gamma(t->H+ b), using a physically motivated definition of tan(beta). We find that the corrections are large, both in the Minimal ... More

Running G and Λat low energies from physics at M_X: possible cosmological and astrophysical implicationsOct 06 2004Jan 03 2005The renormalization group (RG) approach to cosmology is an efficient method to study the possible evolution of the cosmological parameters from the point of view of quantum field theory in curved space-time. In this work we continue our previous investigations ... More

The Relaxed Universe: towards solving the cosmological constant problem dynamically from an effective action functional of gravityDec 03 2009Apr 28 2010We present an unconventional approach for addressing the old cosmological constant (CC) problem in a class of F(R,G) models of modified gravity. For a CC of arbitrary size and sign the corresponding cosmological evolution follows an expansion history ... More

Loop Induced Flavor Changing Neutral Decays of the Top Quark in a General Two-Higgs-Doublet ModelNov 07 2000Feb 13 2001Decays of the top quark induced by flavor changing neutral currents (FCNC) are known to be extremely rare events within the Standard Model. This is so not only for the decay modes into gauge bosons, but most notably in the case of the Higgs channels, ... More

Dark energy perturbations and a possible solution to the coincidence problemApr 21 2009May 04 2009We analyze some generic properties of the dark energy (DE) perturbations, in the case of a self-conserved DE fluid. We also apply a simple test (the "F-test") to compare a model to the data on large scale structure (LSS) under the assumption of negligible ... More

Cosmologies with variable parameters and dynamical cosmon: implications on the cosmic coincidence problemJan 16 2007Dynamical 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 ... More

LXCDM: a cosmon model solution to the cosmological coincidence problem?Apr 11 2006Aug 06 2006We consider the possibility that the total dark energy (DE) of the Universe is made out of two dynamical components of different nature: a variable cosmological term, Lambda, and a dynamical ``cosmon'', X, possibly interacting with Lambda but not with ... More

Dark energy perturbations and cosmic coincidenceSep 20 2008Apr 29 2009While there is plentiful evidence in all fronts of experimental cosmology for the existence of a non-vanishing dark energy (DE) density \rho_D in the Universe, we are still far away from having a fundamental understanding of its ultimate nature and of ... More

Radiative Corrections to scalar quark decays in the MSSMJan 25 2000Feb 10 2000We review the one-loop corrections to the partial decay width of sbottom-quark into a top quark and a chargino for the parameter space relevant to the TESLA e+e- linear collider. We present the results available in the literature for the QCD and the Yukawa ... More

Top quark and charged Higgs at the Tevatron-Run IISep 16 1999We shortly review the top quark decay into charged Higgs, and present new results on its production at the upgraded Tevatron. We have computed the MSSM cross-section for single charged Higgs in association with the top quark beyond the regime of on-shell ... More

Production and FCNC decay of supersymmetric Higgs bosons into heavy quarks in the LHCAug 03 2005Oct 31 2005We analyze the production and subsequent decay of the neutral MSSM Higgs bosons (h = h^0, H^0, A^0) mediated by flavor changing neutral currents (FCNC) in the LHC collider. We have computed the h-production cross-section times the FCNC branching ratio, ... More

LXCDM cosmologies: solving the cosmological coincidence problem?Sep 25 2006Sep 25 2006We explore the possibility of having a composite (self-conserved) dark energy (DE) whose dynamics is controlled by the quantum running of the cosmological parameters. We find that within this scenario it is feasible to find an explanation for the cosmological ... More

Gamma(H+ -> t \bar{b}) in the MSSM: a handle for SUSY charged Higgs at the Tevatron and the LHCMar 01 1999We compute Gamma(H+ -> t \bar{b}) at one-loop in the MSSM and show how future data at the Tevatron and/or at the LHC could be used to unravel the potential SUSY nature of the charged Higgs.

Background history and cosmic perturbations for a general system of self-conserved dynamical dark energy and matterSep 10 2015Nov 14 2015We determine the Hubble expansion and the general cosmic perturbations equations for a general system consisting of self-conserved matter and self-conserved dark energy (DE). While at the background level the two components are non-interacting, they do ... More

Starobinsky-like inflation and running vacuum in the context of SupergravityMay 17 2015Jul 21 2016We describe the primeval inflationary phase of the early Universe within a quantum field theoretical (QFT) framework that can be viewed as the effective action of vacuum decay in the early times. Interestingly enough, the model accounts for the "graceful ... More

Running vacuum in the Universe and the time variation of the fundamental constants of NatureMay 19 2016Mar 31 2017We compute the time variation of the fundamental constants (such as the ratio of the proton mass to the electron mass, the strong coupling constant, the fine structure constant and Newton's constant) within the context of the so-called running vacuum ... More