Massimo Pietroni

Massimo Pietroni
INFN - Istituto Nazionale di Fisica Nucleare | INFN · Padua

About

95
Publications
6,349
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4,104
Citations
Additional affiliations
January 1991 - April 1994
University of Padua
Position
  • PhD Student
February 1997 - present

Publications

Publications (95)
Article
Full-text available
We investigate the role played by symmetries in the perturbative expansion of the large-scale structure. In particular, we establish which of the coefficients of the perturbation theory kernels are dictated by symmetries and which not. Up to third order in perturbations, for the dark matter density contrast (and for the dark matter velocity) only t...
Article
Consistency relations for the large scale structure are exact equalities between correlation functions of different order. These relations descend from the equivalence principle and hold for primordial perturbations generated by single-field models of inflation. They are not affected by nonlinearities and hold also for biased tracers and in redshif...
Article
Full-text available
A model for cold dark matter is given by the solution of a coupled Schrödinger–Poisson equation system. We present a numerical scheme for integrating these equations, discussing the problems arising from their nonlinear and nonlocal character. After introducing and testing our numerical approach, we illustrate key features of the system by numerica...
Preprint
Consistency Relations for the Large Scale Structure are exact equalities between correlation functions of different order. These relations descend from the equivalence principle and hold for primordial perturbations generated by single-field models of inflation. They are not affected by nonlinearities and hold also for biased tracers and in redshif...
Preprint
In order to extract the acoustic scale from galaxy power spectra nonlinear effects have to be modelled accurately. In practice, this is done by adding extra parameters to the theoretical power spectra, which can be determined from N-body simulations, or just treated as nuisance parameters to be marginalized over. However, most of these parameters d...
Article
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Structure formation in 1+1 dimensions is considered, with emphasis on the effects of shell-crossing. The breakdown of the perturbative expansion beyond shell-crossing is discussed, and it is shown, in a simple example, that the perturbative series can be extended to a transseries including nonperturbative terms. The latter converges to the exact re...
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We study a new procedure to measure the sound horizon scale via Baryonic Acoustic Oscillations (BAO). Instead of fitting the measured power spectrum (PS) to a theoretical model containing the cosmological informations and all the nonlinear effects, we define a procedure to project out (or to `extract') the oscillating component from a given nonline...
Article
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We define a procedure to extract the oscillating part of a given nonlinear Power Spectrum, and derive an equation describing its evolution including the leading effects at all scales. The intermediate scales are taken into account by standard perturbation theory, the long range (IR) displacements are included by using consistency relations, and the...
Preprint
We study a new procedure to measure the sound horizon scale via Baryonic Acoustic Oscillations (BAO). Instead of fitting the measured power spectrum (PS) to a theoretical model containing the cosmological informations and all the nonlinear effects, we define a procedure to project out (or to "extract") the oscillating component from a given nonline...
Preprint
We define a procedure to extract the oscillating part of a given nonlinear Power Spectrum, and derive an equation describing its evolution including the leading effects at all scales. The intermediate scales are taken into account by standard perturbation theory, the long range (IR) displacements are included by using consistency relations, and the...
Article
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Many of the methods proposed so far to go beyond Standard Perturbation Theory break invariance under time-dependent boosts (denoted here as extended Galilean Invariance, or GI). This gives rise to spurious large scale effects which spoil the small scale predictions of these approximation schemes. By using consistency relations we derive fully non-p...
Preprint
Many of the methods proposed so far to go beyond Standard Perturbation Theory break invariance under time-dependent boosts (denoted here as extended Galilean Invariance, or GI). This gives rise to spurious large scale effects which spoil the small scale predictions of these approximation schemes. By using consistency relations we derive fully non-p...
Article
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We study the impact of neutrino masses on the shape and height of the BAO peak of the matter correlation function, both in real and redshift space. In order to describe the nonlinear evolution of the BAO peak we run N-body simulations and compare them with simple analytic formulae. We show that the evolution with redshift of the correlation functio...
Preprint
We study the impact of neutrino masses on the shape and height of the BAO peak of the matter correlation function, both in real and redshift space. In order to describe the nonlinear evolution of the BAO peak we run N-body simulations and compare them with simple analytic formulae. We show that the evolution with redshift of the correlation functio...
Article
Time modulations at per mil level have been reported to take place in the decay constant of about 15 nuclei with period of one year (most cases) but also of about one month or one day. In this paper we give the results of the activity measurement of a 40K source and a 232Th one. The two experiments have been done at the Gran Sasso Laboratory during...
Article
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Standard cosmological perturbation theory (SPT) for the Large Scale Structure (LSS) of the Universe fails at small scales (UV) due to strong nonlinearities and to multistreaming effects. In Pietroni et al. 2011 a new framework was proposed in which the large scales (IR) are treated perturbatively while the information on the UV, mainly small scale...
Article
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We present fully nonlinear consistency relations for the squeezed bispectrum of Large Scale Structure. These relations hold when the matter component of the Universe is composed of one or more species, and generalize those obtained in [1,2] in the single species case. The multi-species relations apply to the standard dark matter + baryons scenario,...
Article
Time modulations at per mil level have been reported to take place in the decay constant of about 15 nuclei with period of one year (most cases) but also of about one month or one day. In this paper we give the results of the activity measurement of a 4040K source and a 232232Th one. The two experiments have been done at the Gran Sasso Laboratory d...
Article
Full-text available
Time modulations at per mil level have been reported to take place in the decay constant of about 15 nuclei with period of one year (most cases) but also of about one month or one day. In this paper we first investigate the possibility of an annual modulation induced by the coupling with a scalar field sourced by the Sun. Then, we give the results...
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We study the gravitational clustering of spherically symmetric overdensities and the statistics of the resulting dark matter halos in the "symmetron model", in which a new long range force is mediated by a $Z_2$ symmetric scalar field. Depending on the initial radius of the overdensity, we identify two distinct regimes: for small initial radii the...
Article
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We discuss the constraints imposed on the nonlinear evolution of the Large Scale Structure (LSS) of the universe by galilean invariance, the symmetry relevant on subhorizon scales. Using Ward identities associated to the invariance, we derive fully nonlinear consistency relations between statistical correlators of the density and velocity perturbat...
Article
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A new computational scheme for the nonlinear cosmological matter power spectrum (PS) is presented. Our method is based on evolution equations in time, which can be cast in a form extremely convenient for fast numerical evaluations. A nonlinear PS is obtained in a time comparable to that needed for a simple 1-loop computation, and the numerical impl...
Article
We address the issue of the cosmological bias between matter and galaxy distributions, looking at dark matter haloes as a first step to characterize galaxy clustering. Starting from the linear density field at high redshift, we follow the centre-of-mass trajectory of the material that will form each halo at late times (protohalo). We adopt a fluid-...
Article
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Semi-analytical methods, based on Eulerian perturbation theory, are a promising tool to follow the time evolution of cosmological perturbations at small redshifts and at mildly nonlinear scales. All these schemes are based on two approximations: the existence of a smoothing scale and the single-stream approximation, where velocity dispersion of the...
Article
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We consider a dark energy fluid with arbitrary sound speed and equation of state and discuss the effect of its clustering on the cold dark matter distribution at the non-linear level. We write the continuity, Euler and Poisson equations for the system in the Newtonian approximation. Then, using the time renormalization group method to resum perturb...
Article
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One of the nicest results in cosmological perturbation theory is the analytical resummaton of the leading corrections at large momentum, which was obtained by Crocce and Scoccimarro for the propagator. Using an exact evolution equation, we generalize this result, by showing that a class of next-to-leading corrections can also be resummed at all ord...
Article
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We consider cosmologies in which a dark-energy scalar field interacts with cold dark matter. The growth of perturbations is followed beyond the linear level by means of the time-renormalization-group method, which is extended to describe a multicomponent matter sector. Even in the absence of the extra interaction, a scale-dependent bias is generate...
Article
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We apply the time-renormalization group approach to study the effect of primordial non-Gaussianities in the non-linear evolution of cosmological dark matter density perturbations. This method improves the standard perturbation approach by solving renormalization group-like equations governing the dynamics of gravitational instability. The primordia...
Article
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All the non-trivial features of the Universe we see around us, such as particles, stars, galaxies, and clusters of galaxies, are the result of non-equilibrium processes in the cosmic evolution. These lectures aim to provide some general background in cosmology and to examine specific, and notable, examples of departures from thermal equilibrium. Th...
Article
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Future large scale structure observations are expected to be sensitive to small neutrino masses, of the order of 0.05 eV or more. However, forecasts are based on the assumption that by the time at which these datasets will be available, the non-linear spectrum in presence of neutrino mass will be predicted with an accuracy at least equal to the neu...
Article
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Non-linear effects are crucial for computing the cosmological matter power spectrum to the accuracy required by future generation surveys. Here, a new approach is presented, in which the power spectrum, the bispectrum and higher order correlations are obtained—at any redshift and for any momentum scale—by integrating a system of differential equati...
Article
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We determine under what conditions Scalar Tensor cosmologies predict an expansion rate which is reduced as compared to the standard General Relativity case. We show that ST theories with a single matter sector typically predict an enchanced Hubble rate in the past, as a consequence of the requirement of an attractive fixed point towards General Rel...
Article
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This Conference is the fifth of a series of Workshops on High Energy Gamma- ray Experiments, following the Conferences held in Perugia 2003, Bari 2004, Cividale del Friuli 2005, Elba Island 2006. This year the focus was on the use of gamma-ray to study the Dark Matter component of the Universe, the origin and propagation of Cosmic Rays, Extra Large...
Article
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Inflationary observables, like the power spectrum, computed at one-order and higher-order loop level seem to be plagued by large infra-red corrections. In this short note, we point out that these large infra-red corrections appear only in quantities which are not directly observable. This is in agreement with general expectations concerning infra-r...
Article
Many interesting cosmological models predict an enhancement of the Hubble expansion rate in the early Universe. Among these are some braneworld models, models with a kination phase and scalar-tensor models. In this paper we show that the pre Big Bang Nucleosynthesis (pre-BBN) enhancement can be strongly constrained by the combined use of the bounds...
Article
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The physical equivalence of Einstein and Jordan frames in scalar–tensor theories was explained by Dicke in 1962: they are related by a local transformation of units. We discuss this point in a cosmological framework. Our main result is the construction of a formalism in which all the physical observables are frame-invariant. The application of this...
Article
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Considering the general Lagrangian of k-essence models, we study and classify them through variables connected to the fluid equation of state parameter w_\kappa. This allows to find solutions around which the scalar field describes a mixture of dark matter and cosmological constant-like dark energy, an example being the purely kinetic model propose...
Article
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Renormalization Group techniques, successfully employed in quantum field theory and statistical physics, are applied to study the dynamics of structure formation in the Universe. A semi-analytic approach to the computation of the nonlinear power-spectrum of dark matter density fluctuations is proposed. The method can be applied down to zero redshif...
Article
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Renormalization Group (RG) techniques have been successfully employed in quantum field theory and statistical physics. Here we apply RG methods to study the non-linear stages of structure formation in the Universe. Exact equations for the power spectrum, the bispectrum, and all higher order correlation functions can be derived for any underlying co...
Preprint
Considering the general Lagrangian of k-essence models, we study and classify them through variables connected to the fluid equation of state parameter w_\kappa. This allows to find solutions around which the scalar field describes a mixture of dark matter and cosmological constant-like dark energy, an example being the purely kinetic model propose...
Preprint
The physical equivalence of Einstein and Jordan frame in Scalar Tensor theories has been explained by Dicke in 1962: they are related by a local transformation of units. We discuss this point in a cosmological framework. Our main result is the construction of a formalism in which all the physical observables are frame-invariant. The application of...
Article
Full-text available
A host of dark energy models and non-standard cosmologies predict an enhanced Hubble rate in the early Universe: perfectly viable models, which satisfy Big Bang Nucleosynthesis (BBN), cosmic microwave background and general relativity tests, may nevertheless lead to enhancements of the Hubble rate up to many orders of magnitude. In this paper we sh...
Article
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Scalar-Tensor theories of gravity can be formulated in different frames, most notably, the Einstein and the Jordan one. While some debate still persists in the literature on the physical status of the different frames, a frame transformation in Scalar-Tensor theories amounts to a local redefinition of the metric, and then should not affect physical...
Article
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The two most popular candidates for dark energy, i.e. a cosmological constant and quintessence, are very difficult to distinguish observationally, mostly because the quintessence field does not have sizable fluctuations. We study a scalar field model for dark energy in which the scalar field is invariant under reflection symmetry, phi -> -phi. Unde...
Article
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A scalar field interacting differently with dark matter and baryons may explain why their ratio is of order unity today. We provide three working examples, checking them against the observations of CMB, Large Scale Structure, supernovae Ia, and post-newtonian tests of gravity. Such a scenario could make life much easier for supersymmetric dark matt...
Article
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In Scalar-Tensor theories of gravity, the expansion rate of the universe in the past may differ considerably from the standard one. After imposing the constraints coming from nucleosynthesis, CMB, type Ia supernovae, and solar system tests of General Relativity, we consider the expansion rate of the universe at WIMP decoupling, showing that it can...
Article
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Scalar-tensor theories of gravity provide a consistent framework to accommodate an ultra-light quintessence scalar field. While the equivalence principle is respected by construction, deviations from General Relativity and standard cosmology may show up at nucleosynthesis, CMB, and solar system tests of gravity. After imposing all the bounds coming...
Article
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Can local fluctuations of a “quintessence” scalar field play a dynamical role in the gravitational clustering and cosmic structure formation process? We address this question in the general framework of scalar-tensor theories of gravity. Nonlinear energy density perturbations, both in the scalar field and matter component, and linear metric perturb...
Article
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Non-linear gravitational clustering in a universe dominated by dark energy, modelled by a `quintessence' scalar field, and cold dark matter with space-time varying mass is studied. Models of this type, where the variable mass is induced by dependence on the scalar field, as suggested by string theory or extra-dimensions, have been proposed as a via...
Article
It is a puzzle why the densities of dark matter and dark energy are nearly equal today when they scale so differently during the expansion of the universe. This conundrum may be solved if there is a coupling between the two dark sectors. In this paper we assume that dark matter is made of cold relics with masses depending exponentially on the scala...
Article
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The so called `cosmic coincidence' problem seems to suggest a coupling between dark energy and dark matter. A possibility could be given by dark matter particles with masses depending exponentially on the scalar field associated to dark energy. If the latter also has an exponential potential, attractor solutions exist with constant Omega_{DM} and O...
Article
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We report on an educational project in particle physics based on Feynman diagrams. By dropping the mathematical aspect of the method and keeping just the iconic one, it is possible to convey many different concepts from the world of elementary particles, such as antimatter, conservation laws, particle creation and destruction, real and virtual part...
Article
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Brane world models with `large' extra dimensions with radii in the r_l ~ 0.01- 0.1 mm range and smaller ones at r_s < (1 TeV)^(-1) have the potential to solve the cosmic coincidence problem, i.e. the apparently fortuitous equality between dark matter and dark energy components today. The main ingredient is the assumption of a stabilization mechanis...
Article
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The noncommutative version of the Euclidean g2phi4 theory is considered. By using Wilsonian flow equations the ultraviolet renormalizability can be proved to all orders in perturbation theory. On the other hand, the infrared sector cannot be treated perturbatively and requires a resummation of the leading divergences in the two-point function. This...
Article
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The aim of this project is to communicate the basic laws of particle physics with Feynman diagrams - visual tools which represent elementary particle processes. They were originally developed as a code to be used by physicists and are still used today for calculations and elaborations of theoretical nature. The technical and mathematical rules of F...
Article
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Viene presentato un progetto di comunicazione scientifica dei concetti di base della fisica delle particelle basato sull'uso dei diagrammi di Feynman. Questi sono rappresentazioni dei processi tra particelle elementari nate all'interno della comunità dei fisici e tuttora correntemente utilizzati come strumento di calcolo e di elaborazione teorica....
Article
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Matsumoto and Yoshimura have recently argued that the number density of heavy particles in a thermal bath is not necessarily Boltzmann-suppressed for T<<M, as power law corrections may emerge at higher orders in perturbation theory. This fact might have important implications on the determination of WIMP relic densities. On the other hand, the defi...
Article
Full-text available
We study the IR/UV connection of the four-dimensional non-commutative phi^4 theory by using the Wilsonian Renormalization Group equation. Extending the usual formulation to the non-commutative case we are able to prove UV renormalizability to all orders in perturbation theory. The full RG equations are finite in the IR, but perturbative approximati...
Article
Full-text available
Matsumoto and Yoshimura have recently argued that the number density of heavy particles in a thermal bath is not necessarily Boltzmann-suppressed for T << M, as power law corrections may emerge at higher orders in perturbation theory. This fact might have important implications on the determination of WIMP relic densities. On the other hand, the de...
Preprint
Matsumoto and Yoshimura have recently argued that the number density of heavy particles in a thermal bath is not necessarily Boltzmann-suppressed for T << M, as power law corrections may emerge at higher orders in perturbation theory. This fact might have important implications on the determination of WIMP relic densities. On the other hand, the de...
Article
Full-text available
Recent data point in the direction of a cosmological constant dominated universe. We investigate the role of supersymmetric QCD with Nf<Nc as a possible candidate for a dynamical cosmological constant (“quintessence”). When Nf>1, the multiscalar dynamics is fully taken into account, showing that a certain degree of flavor symmetry in the initial co...
Article
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Scalar fields with inverse power-law effective potentials may provide a negative pressure component to the energy density of the universe today, as required by cosmological observations. In order to be cosmologically relevant today, the scalar field should have a mass $m_\phi = O(10^{-33} {\mathrm eV})$, thus potentially inducing sizable violations...
Article
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The formation of topological defects in a second order phase transition in the early universe is an out-of-equilibrium process. Condensed matter experiments seem to support Zurek's mechanism, in which the freezing of thermal fluctuations close to the critical point (critical slowing down) plays a crucial role. We discuss how this picture can be ext...
Article
The presence of a primordial magnetic field in the early universe affects the dynamic of the electroweak phase transition enhancing its strength. This effect may enlarge the window for electroweak baryogenesis in the minimal supersymmetric extension of the standard model or even resurrect the electroweak baryogenesis scenario in the standard model....
Article
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The Thermal Renormalization Group can be employed to study the dynamics of $T\neq 0$ Quantum Field Theories close to second order phase transitions, where neither resummed perturbation theory nor first principle lattice simulations can be employed. As an example, I discuss the computation of the plasmon damping rate in the scalar field theory from...
Article
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The plasmon damping rate in scalar field theory is computed close to the critical temperature. It is shown that the divergent result obtained in perturbation theory is a consequence of neglecting the thermal renormalization of the coupling. Taking this effect into account, a vanishing damping rate is obtained, leading to the critical slowing down o...
Article
We apply a gauge invariant formulation of Wilson Renormalization Group (RG) to the computation of the Debye and transverse gluon masses in pure gauge SU(N) at high temperature. Following the Hard Thermal Loop effective field theory as a guideline, we develop an approximation scheme to the exact evolution equations.The Debye mass receives sizable co...
Preprint
We apply a gauge invariant formulation of Wilson Renormalization Group (RG) to the computation of the Debye and transverse gluon masses in pure gauge SU(N) at high temperature. Following the Hard Thermal Loop effective field theory as a guideline, we develop an approximation scheme to the exact evolution equations. The Debye mass receives sizable c...
Article
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I describe an application of Wilson Renormalization group to the real time formalism of finite temperature field theory. The approach has two nice features: 1) the RG flow equations describe non-perturbatively the effect of thermal fluctuations only, and, 2) the flow is gauge invariant. I then describe the application of the method to the study of...
Article
We discuss the question of inverse symmetry breaking at non-zero temperature using the exact renormalization group. We study a two-scalar theory and concentrate on the nature of the phase transition during which the symmetry is broken. We also examine the persistence of symmetry breaking at temperatures higher than the critical one.
Article
The paper ``Transversality of the Gluon Self-Energy at Finite Temperature in General Covariant Gauges'' has been withdrawn.
Preprint
We discuss the question of inverse symmetry breaking at non-zero temperature using the exact renormalization group. We study a two-scalar theory and concentrate on the nature of the phase transition during which the symmetry is broken. We also examine the persistence of symmetry breaking at temperatures higher than the critical one.
Article
We propose a gauge-invariant version of Wilson Renormalization Group for thermal field theories in real time. The application to the computation of the thermal masses of the gauge bosons in an SU(N) Yang-Mills theory is discussed. Comment: 23 pages, latex2e, 1 EPS figure. The discussions of BRS identities and of the RG kernel have been modified. Fi...
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Motivated by cosmological applications such as electroweak baryogenesis, we develop a field theoretic approach to the computation of particle currents on a space-time-dependent and {ital CP}-violating Higgs background in the adiabatic limit. We consider the standard model with two Higgs doublets and {ital CP} violation in the scalar sector, and com...
Article
We apply Renormalization Group techniques to the Real Time formulation of thermal field theory. Due to the separation between the $T=0$ and the $T\neq 0$ parts of the propagator in this formalism, one can derive exact evolution equations for the Green functions describing the effect of integrating out thermal fluctuations of increasing wavelengths,...
Preprint
We apply Renormalization Group techniques to the Real Time formulation of thermal field theory. Due to the separation between the $T=0$ and the $T\neq 0$ parts of the propagator in this formalism, one can derive exact evolution equations for the Green functions describing the effect of integrating out thermal fluctuations of increasing wavelengths,...
Article
We reconsidered the spontaneous baryogenesis mechanism by Cohen, Kaplan and Nelson. Using linear response theory, we calculate the modifications on the thermal averages of the charges of the system due to the presence of a space time dependent “charge potential” l'or a quantum number not orthogonal to baryon number. The local equilibrium configurat...
Article
We compute the particle currents induced on a bubble wall background at finite temperature in a model with CP violation in the Higgs sector. Using a field theory approach we show that fermionic currents arise at one loop, so that a suppression factor with respect to previous computations is found. The contributions to the Higgs currents are also de...
Preprint
We compute the particle currents induced on a bubble wall background at finite temperature in a model with CP violation in the Higgs sector. Using a field theory approach we show that fermionic currents arise at one loop, so that a suppression factor ${\cal O}(h_t \phi/\pi T)^2$ with respect to previous computations is found. The contributions to t...
Article
We study the implications of a light stop for the spontaneous CP breaking at finite temperature in the Higgs sector of the Minimal Supersymmetric Standard Model with a gauge singlet. Assuming CP conservation at zero temperature, we show that the presence of a large mixing between the left- and the right-handed stops can trigger easily the spontaneo...
Article
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We study spontaneous CP breaking at finite temperature in the Higgs sector in the minimal supersymmetric standard model with a gauge singlet. We consider the contribution of the standard model particles and that of top squarks, charginos, neutralinos, and charged and neutral Higgs bosons to the one-loop effective potential. Plasma effects for all b...
Article
Full-text available
The spontaneous baryogenesis mechanism by Cohen, Kaplan and Nelson is reconsidered taking into account the transport of particles inside the electroweak bubble walls. Using linear response theory, we calculate the modifications on the thermal averages of the charges of the system due to the presence of a space time dependent `charge potential' for...
Preprint
We study the spontaneous CP breaking at finite temperature in the Higgs sector in the Minimal Supersymmetric Standard Model with a gauge singlet. We consider the contribution of the standard model particles and that of stops, charginos, neutralinos, charged and neutral Higgs boson to the one-loop effective potential. Plasma effects for all bosons a...
Article
We reconsider the possibility of spontaneous breaking of R parity in the minimal supersymmetric standard model. By a renormalization group analysis we find the parameter space in which a sneutrino gets a vacuum expectation value, leading to the spontaneous breaking of the lepton number and to the appearance of a phenomenologically unacceptable mass...
Article
We investigate the effects of the spontaneous CP violation at finite temperature in the Minimal Supersymmetric Standard Model on the baryogenesis at the weak scale. After a brief discussion of the case in which the electroweak phase transition is of second order, we study in details the baryogenesis scenario when the transition proceeds via bubble...
Preprint
We reconsider the possibility of spontaneous breaking of $R$ parity in the Minimal Supersymmetric Standard Model. By a renormalization group analysis we find the parameter space in which a sneutrino gets a vacuum expectation value, leading to the spontaneous breaking of the lepton number and to the appearance of a phenomenologically unacceptable ma...
Article
We investigate the implications of neutrino electromagnetic dipole moments for the radiative decay $\pi \rightarrow e \nu \gamma$. We show that the dominant new effect comes from the interference between the amplitude of the process with the photon emitted by the neutrino and the structure dependent standard amplitude. Such interference takes place...
Preprint
We investigate the implications of neutrino electromagnetic dipole moments for the radiative decay $\pi \rightarrow e \nu \gamma$. We show that the dominant new effect comes from the interference between the amplitude of the process with the photon emitted by the neutrino and the structure dependent standard amplitude. Such interference takes place...
Article
We show that in the Minimal Supersymmetric Standard Model one-loop effects at finite temperature may lead to a spontaneous breaking of CP invariance in the scalar sector. Requiring that the breaking takes place at the critical temperature for the electroweak phase transition, we find that the parameter space is compatible with a mass of the Higgs p...
Article
We study the supersymmetrized version of the singlet majoron model and, performing an analysis of the renormalization-group improved potential, we find that a spontaneous breaking of R-parity can be achieved for a wide range of the parameters. Studying the finite-temperature effective potential, we show that the phase transition leading to R-parity...
Article
We study the electroweak phase transition in a supersymmetric version of the Standard Model, in which a gauge singlet superfield is added to the Higgs sector. We show that the order of the transition is determined by the trilinear soft supersymmetry breaking terms rather than by the $O ( m^{3} T )$ term in the 1-loop, $T\neq0$ corrections. This fac...
Article
By using a QCD relativistic potential model we compute several physical quantities for heavy-light-quark Qq¯ mesons: current-particle matrix elements, leptonic decay constants in the limit mQ-->∞, and the Kobayashi-Maskawa matrix elements Vbu and Vbc from recent CLEO and ARGUS data on semileptonic inclusive B decays. A comparison with other theoret...