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José Ramón Espinosa

Other affiliations: IFAE, University of Hamburg, CERN  ...read more
Bio: José Ramón Espinosa is an academic researcher from Spanish National Research Council. The author has contributed to research in topics: Higgs boson & Electroweak interaction. The author has an hindex of 54, co-authored 126 publications receiving 11942 citations. Previous affiliations of José Ramón Espinosa include IFAE & University of Hamburg.


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors presented the first complete next-to-next-toleading order analysis of the Standard Model Higgs potential, showing that at the Planck scale, absolute stability of the potential is not guaranteed at 98% C.L. for Mh < 126 GeV.
Abstract: We present the rst complete next-to-next-to-leading order analysis of the Standard Model Higgs potential. We computed the two-loop QCD and Yukawa corrections to the relation between the Higgs quartic coupling ( ) and the Higgs mass (Mh), reducing the theoretical uncertainty in the determination of the critical value of Mh for vacuum stability to 1 GeV. While at the Planck scale is remarkably close to zero, absolute stability of the Higgs potential is excluded at 98% C.L. for Mh < 126 GeV. Possible consequences of the near vanishing of at the Planck scale, including speculations about the role of the Higgs eld during ination, are discussed.

1,429 citations

Journal ArticleDOI
TL;DR: In this paper, the instability and metastability bounds of the Standard Model electroweak vacuum were updated in view of the recent ATLAS and CMS Higgs results, and the authors derived an upper bound on the mass of heavy right-handed neutrinos by requiring that their Yukawa couplings do not destabilize the Higgs potential.

575 citations

Journal ArticleDOI
TL;DR: In this article, a renormalization-group improved leading-log approximation was proposed for the Higgs spectrum and couplings, where the renormalisation scale is fixed to the top-quark pole mass.

521 citations

Journal ArticleDOI
TL;DR: In this article, it was shown that the effective-theory approach upon which that claim is based ceases to be valid beyond a cutoff scale, and that the extrapolation of the pure SM potential beyond this cutoff scale is unwarranted and the scenario is akin to other ad hoc inflaton potentials afflicted with significant fine-tuning.
Abstract: We critically examine the recent claim that the standard model (SM) Higgs boson $\mathcal{H}$ could drive inflation in agreement with observations if $|\mathcal{H}{|}^{2}$ has a strong coupling $\ensuremath{\xi}\ensuremath{\sim}{10}^{4}$ to the Ricci curvature scalar. We first show that the effective-theory approach upon which that claim is based ceases to be valid beyond a cutoff scale $\ensuremath{\Lambda}={m}_{p}/\ensuremath{\xi}$, where ${m}_{p}$ is the reduced Planck mass. We then argue that knowing the Higgs potential profile for the field values relevant for inflation ($|\mathcal{H}|g{m}_{p}/\sqrt{\ensuremath{\xi}}\ensuremath{\gg}\ensuremath{\Lambda}$) requires knowledge of the ultraviolet completion of the SM beyond $\ensuremath{\Lambda}$. In absence of such microscopic theory, the extrapolation of the pure SM potential beyond $\ensuremath{\Lambda}$ is unwarranted and the scenario is akin to other ad hoc inflaton potentials afflicted with significant fine-tuning. The appealing naturalness of this minimal proposal is therefore lost.

521 citations

Journal ArticleDOI
TL;DR: In this article, the authors study the hydrodynamics of bubble growth in first-order phase transitions and predict the size of the gravity wave signal resulting from bubble collisions, which depends on both the bubble wall velocity and the plasma fluid velocity.
Abstract: The study of the hydrodynamics of bubble growth in first-order phase transitions is very relevant for electroweak baryogenesis, as the baryon asymmetry depends sensitively on the bubble wall velocity, and also for predicting the size of the gravity wave signal resulting from bubble collisions, which depends on both the bubble wall velocity and the plasma fluid velocity. We perform such study in different bubble expansion regimes, namely deflagrations, detonations, hybrids (steady states) and runaway solutions (accelerating wall), without relying on a specific particle physics model. We compute the efficiency of the transfer of vacuum energy to the bubble wall and the plasma in all regimes. We clarify the condition determining the runaway regime and stress that in most models of strong first-order phase transitions this will modify expectations for the gravity wave signal. Indeed, in this case, most of the kinetic energy is concentrated in the wall and almost no turbulent fluid motions are expected since the surrounding fluid is kept mostly at rest.

506 citations


Cited by
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Journal ArticleDOI
Claude Amsler1, Michael Doser2, Mario Antonelli, D. M. Asner3  +173 moreInstitutions (86)
TL;DR: This biennial Review summarizes much of particle physics, using data from previous editions.

12,798 citations

Journal ArticleDOI
TL;DR: The Pythia program as mentioned in this paper can be used to generate high-energy-physics ''events'' (i.e. sets of outgoing particles produced in the interactions between two incoming particles).
Abstract: The Pythia program can be used to generate high-energy-physics ''events'', i.e. sets of outgoing particles produced in the interactions between two incoming particles. The objective is to provide as accurate as possible a representation of event properties in a wide range of reactions, within and beyond the Standard Model, with emphasis on those where strong interactions play a role, directly or indirectly, and therefore multihadronic final states are produced. The physics is then not understood well enough to give an exact description; instead the program has to be based on a combination of analytical results and various QCD-based models. This physics input is summarized here, for areas such as hard subprocesses, initial- and final-state parton showers, underlying events and beam remnants, fragmentation and decays, and much more. Furthermore, extensive information is provided on all program elements: subroutines and functions, switches and parameters, and particle and process data. This should allow the user to tailor the generation task to the topics of interest.

6,300 citations

Journal ArticleDOI
01 Dec 1949-Nature
TL;DR: Wentzel and Jauch as discussed by the authors described the symmetrization of the energy momentum tensor according to the Belinfante Quantum Theory of Fields (BQF).
Abstract: To say that this is the best book on the quantum theory of fields is no praise, since to my knowledge it is the only book on this subject But it is a very good and most useful book The original was written in German and appeared in 1942 This is a translation with some minor changes A few remarks have been added, concerning meson theory and nuclear forces, also footnotes referring to modern work in this field, and finally an appendix on the symmetrization of the energy momentum tensor according to Belinfante Quantum Theory of Fields Prof Gregor Wentzel Translated from the German by Charlotte Houtermans and J M Jauch Pp ix + 224, (New York and London: Interscience Publishers, Inc, 1949) 36s

2,935 citations

Journal ArticleDOI
TL;DR: In this article, theoretical and phenomenological aspects of two-Higgs-doublet extensions of the Standard Model are discussed and a careful study of spontaneous CP violation is presented, including an analysis of the conditions which have to be satisfied in order for a vacuum to violate CP.

2,395 citations

Journal ArticleDOI
TL;DR: In this article, the neutralino is considered as a superpartner in many supersymmetric theories, and the cosmological abundance of neutralino and the event rates for both direct and indirect detection schemes are discussed.
Abstract: There is almost universal agreement among astronomers that most of the mass in the Universe and most of the mass in the Galactic halo is dark. Many lines of reasoning suggest that the dark matter consists of some new, as yet undiscovered, weakly-interacting massive particle (WIMP). There is now a vast experimental effort being surmounted to detect WIMPS in the halo. The most promising techniques involve direct detection in low-background laboratory detectors and indirect detection through observation of energetic neutrinos from annihilation of WIMPs that have accumulated in the Sun and/or the Earth. Of the many WIMP candidates, perhaps the best motivated and certainly the most theoretically developed is the neutralino, the lightest superpartner in many supersymmetric theories. We review the minimal supersymmetric extension of the Standard Model and discuss prospects for detection of neutralino dark matter. We review in detail how to calculate the cosmological abundance of the neutralino and the event rates for both direct- and indirect-detection schemes, and we discuss astrophysical and laboratory constraints on supersymmetric models. We isolate and clarify the uncertainties from particle physics, nuclear physics, and astrophysics that enter at each step in the calculation. We briefly review other related dark-matter candidates and detection techniques.

2,047 citations