On the Potential of Leptonic Minimal Flavour Violation

Minimal Flavour Violation can be realized in several ways in the lepton sector due to the possibility of Majorana neutrino mass terms. We derive the scalar potential for the fields whose background values are the Yukawa couplings, for the simplest See-Saw model with just two right-handed neutrinos, and explore its minima. The Majorana character plays a distinctive role: the minimum of the potential allows for large mixing angles -in contrast to the simplest quark case- and predicts a maximal Majorana phase. This points in turn to a strong correlation between neutrino mass hierarchy and mixing pattern.Comment: 6 pages; version published on Physics Letters

Large gauge invariant non-standard neutrino interactions

Theories beyond the Standard Model must necessarily respect its gauge symmetry. This implies strict constraints on the possible models of non-standard neutrino interactions, which we analyze. The focus is set on the effective low-energy dimension six and eight operators involving four leptons, decomposing them according to all possible tree-level mediators, as a guide for model building. The new couplings are required to have sizeable strength, while processes involving four charged leptons are required to be suppressed. For non-standard interactions in matter, only diagonal tau-neutrino interactions can escape these requirements and can be allowed to result from dimension six operators. Large non-standard neutrino interactions from dimension eight operators alone are phenomenologically allowed in all flavour channels and shown to require at least two new mediator particles. The new couplings must obey general cancellation conditions both at the dimension six and eight levels, which result from expressing the operators obtained from the mediator analysis in terms of a complete basis of operators. We illustrate with one example how to apply this information to model building.Comment: 34 pages, 4 figures, 5 tables. Final version in PR

Dark Coupling and Gauge Invariance

We study a coupled dark energy-dark matter model in which the energy-momentum exchange is proportional to the Hubble expansion rate. The inclusion of its perturbation is required by gauge invariance. We derive the linear perturbation equations for the gauge invariant energy density contrast and velocity of the coupled fluids, and we determine the initial conditions. The latter turn out to be adiabatic for dark energy, when assuming adiabatic initial conditions for all the standard fluids. We perform a full Monte Carlo Markov Chain likelihood analysis of the model, using WMAP 7-year data.Comment: 16 pages, 2 figures, version accepted for publication in JCA

El tratamiento de la amistad y el poder en “Amigo, amante y leal”, de Calderón, frente a otras comedias palatinas

Merece cierta atención el modo en que se articulan la intersección temática y genérica que parece darse en las comedias de amistad. En este trabajo, a través del análisis de las figuras del poderoso y de los nobles subalternos, nos proponemos mostrar cómo se imbrican las relaciones de amistad y de poder en varias comedias de Calderón y Tirso de Molina, partiendo de aquella que ha sido señalada como emblemática en este subgénero temático: la calderoniana Amigo, amante y leal. ¿Retratan las comedias la amistad entre los poderosos y quien les sirve, cumpliéndose la «difuminación de las desigualdades sociales» propia del género o la amistad está reservada solo para iguales? ¿Muestran las comedias palatinas una amistad sin fisuras que nace de la integridad moral o hay espacio para protagonistas que se mueven por otros intereses? ¿Influye el comportamiento del poderoso y del protagonista en la catalogación de la comedia?The thematic and generic intersection that seems to occur in friendship comedies deserves to devote some attention to the way they are articulated. In this work, through the analysis of the characters of the powerful and of the subordinate nobles, we propose to show how the relations of friendship and power are interwoven in various comedies by Calderón and Tirso de Molina, starting from the one that has been indicated as emblematic in this thematic subgenre, the Calderonian Amigo, amante y leal. Do comedies portray friendship between the powerful and those who serve them, fulfilling the «blurring of social inequalities» characteristic of the genre, or is friendship reserved only for equals? Do palatine comedies show a seamless friendship that is born of moral integrity or is there room for protagonists who are moved by other interests? Does the behavior of the powerful and the protagonist influence the cataloging of the comedy

La historia reciente, la materia bíblica y la ficción en la reescritura de Agustín Moreto

Las recientes investigaciones sobre la obra de Agustín Moreto han puesto de manifiesto la necesidad de desterrar, o cuando menos revisar minuciosamente, la idea de que el dramaturgo madrileño se limitaba a plagiar comedias ajenas. En el presente trabajo analizo el tratamiento dado por Moreto a materiales variopintos como los sucesos de la historia reciente, la Biblia o la ficción, a la hora de escribir, solo o en colaboración, El bruto de Babilonia, La cena del rey Baltasar y De fuera vendrá, a partir de comedias de otros autores. Este estudio me ha permitido observar unas técnicas que van mucho más allá de la simple copia. El autor selecciona sus antecedentes siguiendo criterios dramáticos, pero también intereses biográficos coyunturales; no duda en acudir a las fuentes anteriores o ajenas a su antecedente literario para mejorar la trama, actualizarla o ajustarla a sus deseos personales y, finalmente, no desecha los motivos sino que los reutiliza creando sugerentes intertextualidades dentro de su producción.Recent research about Agustín Moreto’s work have evidenced the need to do away with, or at least thoroughly revise, the idea that the playwright from Madrid limited himself to plagiarize somebody else’s plays. The present paper analyses how Moreto worked with diverse motifs such as the events of recent history, the Bible, or fiction when writing, alone or co-authoring a) El bruto de Babilonia, b) La cena del rey Baltasar and c) De fuera vendrá from other writers’ plays. In this work, we can observe techniques which go far beyond the mere copy. The author selects his antecedents following dramatic criteria, but also considering current biographic interests. He does not hesitate to turn to sources previous or alien to his literary antecedent to improve, update, or adjust the plot to his own desires. Finally, the author does not discard the motifs, but he re-uses them creating suggestive intertextuality within his own production

Baryogenesis from the Kobayashi-Maskawa Phase

The Standard Model fulfills the three Sakharov conditions for baryogenesis. The smallness of quark masses suppresses, however, the CP violation from the Kobayashi-Maskawa phase to a level that is many orders of magnitude below what is required to explain the observed baryon asymmetry. We point out that if, as a result of time variation in the Yukawa couplings, quark masses were large at the time of the electroweak phase transition, then the Kobayashi-Maskawa mechanism could be the source of the asymmetry. The Froggatt-Nielsen mechanism provides a plausible framework where the Yukawa couplings could all be of order one at that time, and settle to their present values before nucleosynthesis. The problems related to a strong first order electroweak phase transition may also be alleviated in this framework. Our scenario reveals a loophole in the commonly held view that the Kobayashi-Maskawa mechanism cannot be the dominant source of CP violation to play a role in baryogenesis.Comment: 4 page

First-Order Electroweak Phase Transition in the Standard Model with a Low Cutoff

We study the possibility of a first-order electroweak phase transition (EWPT) due to a dimension-six operator in the effective Higgs potential. In contrast with previous attempts to make the EWPT strongly first-order as required by electroweak baryogenesis, we do not rely on large one-loop thermally generated cubic Higgs interactions. Instead, we augment the Standard Model (SM) effective theory with a dimension-six Higgs operator. This addition enables a strong first-order phase transition to develop even with a Higgs boson mass well above the current direct limit of 114 GeV. The phi^6 term can be generated for instance by strong dynamics at the TeV scale or by integrating out heavy particles like an additional singlet scalar field. We discuss conditions to comply with electroweak precision constraints, and point out how future experimental measurements of the Higgs self couplings could test the idea.Comment: 5 pages, 4 figures. v2: corrected typos, improved discussion of the case lambda<0 and added references. To be published in PR

Relations among Zero Momentum Correlators for Heavy-Light Systems in QCD

Relations connecting various zero momentum correlators of interpolating fields for pseudoscalar and scalar channel, containing one heavy and one light quark field, are derived from the Euclidean space formulation of the QCD functional integral. These relations may serve as constraints on the phenomenological models or approaches motivated from QCD, and suggest a method to extract the chiral quark condensates. It is also found that the correlator for pseudoscalar channel differs from that for scalar channel even in the large heavy quark mass limit.Comment: 9 pages in ReVTeX, UMD preprint #94-14

Particle Currents in a Space-Time dependent and CP-violating Higgs Background: a Field Theory Approach

Motivated by cosmological applications like electroweak baryogenesis, we develop a field theoretic approach to the computation of particle currents on a space-time dependent and CP-violating Higgs background. We consider the Standard Model model with two Higgs doublets and CP violation in the scalar sector, and compute both fermionic and Higgs currents by means of an expansion in the background fields. We discuss the gauge dependence of the results and the renormalization of the current operators, showing that in the limit of local equilibrium, no extra renormalization conditions are needed in order to specify the system completely.Comment: 21 pages, LaTeX file, uses epsf.sty. 4 figures available as a compressed .ep