18 research outputs found
Higgs physics as a window of the electroweak epoch
No full textThis dissertation investigates three well-motivated scalar extensions of the Standard Model and shows that the combination of constraints from collider experiments, from the evolution of the early Universe, and from future astrophysical experiments, such as GW interferometers, will be very valuable for probing the parameter space of those models.In particular, extensions of the Higgs sector of the Standard Model allow for a rich cosmological history around the electroweak scale. In the two-Higgs-doublet model (2HDM) and its real singlet extension (the N2HDM), we determine the parameter regions featuring a first-order EW phase transition (FOEWPT), but also the regions where other effects occur such as electroweak symmetry non-restoration (SnR) at high temperature. We further show that the presence of vacuum trapping can impede a strong FOEWPT in parameter space regions that previously were considered promising for the realisation of electroweak baryogenesis.We analyse these phenomena and in particular their relation to each other, and discuss their connection to the predicted phenomenology at the LHC. Specifically for the 2HDM, we study whether the parameter space region featuring a strong FOEWPT can be probed in the future with the space-based gravitational-wave (GW) telescope LISA via the detection of the associated stochastic GW background. We find that only very contrived regions of the parameter space can give rise to GW signals that are detectable at LISA. We point out that these regions predict indications of new physics at energy scales that will already be probed at the HL-LHC by means of searches for new physics at the TeV scale or the experimental information on the self-coupling of the Higgs boson at 125 GeV. We also investigate a complex singlet extension of the 2HDM, the S2HDM, which contains a pseudo-Nambu-Goldstone dark matter (DM) candidate. In this model, the cross sections for the scattering of the DM on nuclei vanish at tree-level in the limit of zero momentum-transfer due to a U(1) symmetry. However, this symmetry is softly broken in order to give a mass to the DM particle. As a consequence, non-vanishing scattering cross sections arise at the loop level. On one hand, we confront the model with a multitude of theoretical and experimental constraints and discuss the complementarity between constraints related to the DM sector and to the Higgs sector. On the other hand, we calculate the leading radiative corrections to the DM-nucleon scattering in the S2HDM, and we find that the current cross-section limits from DM direct-detection experiments can hardly constrain the parameter space of the S2HDM. However, the loop-corrected predictions for the scattering cross sections can be well within the reach of future direct-detection experiments
Direct detection of pseudo-Nambu-Goldstone dark matter in a two Higgs doublet plus singlet extension of the SM
No full textWe calculate the leading radiative corrections to the dark-matter-nucleon
scattering in the pseudo-Nambu-Goldstone dark matter model augmented with a
second Higgs doublet (S2HDM). In this model, the cross sections for the
scattering of the dark-matter on nuclei vanishes at tree-level in the limit of
zero momentum-transfer due to a U(1) symmetry. However, this symmetry is softly
broken in order to give a mass to the dark-matter particle. As a consequence,
non-vanishing scattering cross sections arise at the loop level. We find that
the current cross-section limits from dark-matter direct-detection experiments
can hardly constrain the parameter space of the S2HDM. However, the
loop-corrected predictions for the scattering cross sections can be well within
the reach of future direct-detection experiments. As a consequence, future
phenomenological analyses of the S2HDM should take into account cross-section
predictions beyond tree-level and the experimental constraints from dark-matter
direct-detection experiments.Comment: 27 pages, 9 figures, v2: matches published versio
Electroweak Asymmetric Early Universe via a Scalar Condensate
No full textFinite temperature effects in the Standard Model tend to restore the electroweak symmetry in the early universe, but new fields coupled to the higgs field may as well reverse this tendency, leading to the so-called electroweak symmetry non-restoration (EW SNR) scenario. Previous works on EW SNR often assume that the reversal is due to the thermal fluctuations of new fields with negative quartic couplings to the higgs, and they tend to find that a large number of new fields are required. We observe that EW SNR can be minimally realized if the field(s) coupled to the higgs field develop(s) a stable condensate. We show that one complex scalar field with a sufficiently large global-charge asymmetry can develop a condensate as an outcome of thermalization and keep the electroweak symmetry broken up to temperatures well above the electroweak scale. In addition to providing a minimal benchmark model, our work hints on a class of models involving scalar condensates that yield electroweak symmetry non-restoration in the early universe
Reconciling Higgs physics and pseudo-Nambu-Goldstone dark matter in the S2HDM using a genetic algorithm
No full textWe investigate a possible realization ofpseudo-Nambu-Goldstone (pNG) dark matterin the framework of a singlet-extended 2 Higgsdoublet model (S2HDM). pNG dark matter gainedattraction due to the fact that direct-detectionconstraints can be avoided naturally because of themomentum-suppressed scattering cross sections,whereas the relic abundance of dark matter cannevertheless be accounted for via the usual thermalfreeze-out mechanism. We confront the S2HDM witha multitude of theoretical and experimentalconstraints, paying special attention to thetheoretical limitations on the scalar potential,such as vacuum stability and perturbativity.In addition, we discussthe complementarity between constraintsrelated to the dark matter sector, on theone hand, and to the Higgs sector, on the other hand.In our numerical discussion we explore theHiggs funnel region with dark mattermasses around 60GeV using a genetic algorithm.We demonstrate that the S2HDM can easilyaccount for the measured relic abundance whilebeing in agreement with all relevant constraints.We also discuss whether the so-calledcenter-of-galaxy excesses can beaccommodated,possibly incombination with a Higgsboson at about 96GeV that can be the originof the LEP- and the CMS-excess observed at this massin the -quark andthe diphoton final state, respectively
Magnetogenesis with gravitational waves and primordial black hole dark matter
No full textStrongly supercooled first order phase transitions (FOPTs) can produce
primordial black hole (PBH) dark matter (DM) along with observable
gravitational waves (GWs) from bubble collisions. Such FOPTs may also produce
coherent magnetic fields generated by bubble collisions and by turbulence in
the primordial plasma. Here we find that the requirement for PBH DM can produce
large primordial magnetic fields which subsequently yield intergalactic
magnetic fields in the present universe (with magnitude pG across
coherence length scales of - Mpc, assuming maximally
helical magnetic fields) that easily exceed lower bounds from blazar
observations. We follow a largely model independent approach and highlight the
possibility of producing DM and observable multi-messenger magnetic fields and
GW signals visible in next generation experiments.Comment: 8 pages, 3 figure
Fate of electroweak symmetry in the early Universe: Non-restoration and trapped vacua in extended Higgs sectors
No full textExtensions of the Higgs sector of the Standard Model allow for a rich cosmological history around the electroweak scale. We show that besides the possibility of strong first-order phase transitions, which have been thoroughly studied in the literature, also other important phenomena can occur, like the non-restoration of the electroweak symmetry or the existence of vacua in which the Universe becomes trapped, preventing a transition to the electroweak minimum. Focusing on the next-to-minimal two-Higgs-doublet model (N2HDM) of type II and taking into account the existing theoretical and experimental constraints, we identify the scenarios of electroweak symmetry non-restoration, vacuum trapping and first-order phase transition in the thermal history of the Universe. We analyze these phenomena and in particular their relation to each other, and discuss their connection to the predicted phenomenology of the N2HDM at the LHC. Our analysis demonstrates that the presence of a global electroweak minimum of the scalar potential at zero temperature does not guarantee that the corresponding N2HDM parameter space will be physically viable: the existence of a critical temperature at which the electroweak phase becomes the deepest minimum is not sufficient for a transition to take place, necessitating an analysis of the tunnelling probability to the electroweak minimum for a reliable prediction of the thermal history of the Universe
Gravitational Wave Production During Reheating: From the Inflaton to Primordial Black Holes
No full textInternational audienceWe calculate the gravitational waves (GWs) produced by primordial black holes (PBHs) in the presence of the inflaton condensate in the early Universe. Combining the GW production from the evaporation process, the gravitational scattering of the inflaton itself, and the density fluctuations due to the inhomogeneous distribution of PBHs, we propose for the first time a complete coherent analysis of the spectrum, revealing three peaks, one for each source. Three frequency ranges ( kHz, GHz, and PHz, respectively) are expected, each giving rise to a similar GW peak amplitude . We also compare our predictions with current and future GWs detection experiments
Fate of the electroweak symmetry in the early universe: Non-restoration and trapped vacua in the N2HDM
No full textFate of electroweak symmetry in the early Universe: Non-restoration and trapped vacua in the N2HDM
No full textExtensions of the Standard Model (SM) Higgs sectorallow for a rich cosmological history around the electroweak(EW) scale. We show that besides strong firstorder phase transitions, which have thoroughly been studied in the literature in two-Higgs doublet models (2HDM),in the context of the next-to 2HDM (N2HDM)other phenomena like EW symmetry non-restoration or vacuum trappingcan occur in certain regions of theparameter space.Focusing on the type~II N2HDM and taking into accountvarious theoretical and experimental constraints,we demonstrate how these novel finite-temperatureeffects are related and how they can be used to furtherconstrain the parameter space of the model.In particular, we show that the presenceof global EW minimum at zero temperature mightnot be a sufficient requirement for the validityof the vacuum configuration. Moreover, weargue that a calculation of the tunneling probabilityis required to accurately predict the thermalhistory of a parameter point, whereas the appearanceof a critical temperature at which the EW phase becomes the deepest minimum is not sufficientfor a transition to take place
La exposición La memoria del otro en la era de lo global: cuando la curaduría condensa un extenso trabajo de investigación
No full textThe curatorial work of Professor Anna Maria Guasch in the exhibition The memory of the other in the era of the global is rooted in her academic and research career. This exhibition, which toured Bogotá, Santiago de Chile and Havana between 2009 and 2011, reflects the approaches of this author with respect to some of her topics of interest, such as interculturality and the impact of globalization on contemporary art. The proposal is framed in a genealogy of “identity exhibitions”, that begun in 2002 with the curatorship of Okwui Enwezor for Documenta 11 in Kassel, which has been reviewed by the curator herself in her theoretical works and publications. The careful list of artists was expanded with each roaming. Professor Guasch considers the selected projects as “memory repositories” and observes transversal features in them, such as their approach to translation and mediation processes with respect to the contemporary infosphere. In this way, the set proposes a specific planetary geography of places and moments in which dialogues occur between the local and the global, generating a more dynamic understanding of identity narratives under the prism of interculturality.La labor curatorial de la profesora Anna Maria Guasch en la exposición La memoria del otro en la era de lo global enraiza en su trayectoria académica e investigadora. Esta muestra, que itineró por Bogotá, Santiago de Chile y La Habana entre 2009 y 2011, refleja los enfoques de esta autora con respecto a algunos de sus temas de interés, como son la interculturalidad y el impacto de la globalización en el arte contemporáneo. La propuesta se enmarca en una genealogía de “exposiciones identitarias” iniciada en 2002 con la curaduría de Okwui Enwezor para la Documenta 11 de Kassel, que ha sido revisada por la propia comisaria en sus trabajos teóricos y publicaciones. La cuidada lista de artistas fue ampliándose en cada itinerancia. La profesora Guasch considera los proyectos seleccionados como “repositorios de memoria” y observa en ellos rasgos transversales, tales como su abordaje de los procesos de traducción y de mediación respecto a la infoesfera contemporánea. De este modo, el conjunto propone una geografía planetaria específica de lugares y momentos en los que se producen diálogos entre lo local y lo global, generándose una comprensión más dinámica de las narrativas identitarias bajo el prisma de la interculturalidad
