Suchergebnisse

The minimal SO(5) / SO(4) linear σ model is extended including an additional complex scalar field, singlet under the global SO(5) and the Standard Model gauge symmetries. The presence of this scalar field creates the conditions to generate an axion à la KSVZ, providing a solution to the strong CP problem, or an axion-like-particle. Different choices for the PQ charges are possible and lead to physically distinct Lagrangians. The internal consistency of each model necessarily requires the study of the scalar potential describing the SO(5) → SO(4) , electroweak and PQ symmetry breaking. A single minimal scenario is identified and the associated scalar potential is minimised including counterterms needed to ensure one-loop renormalizability. In the allowed parameter space, phenomenological features of the scalar degrees of freedom, of the exotic fermions and of the axion are illustrated. Two distinct possibilities for the axion arise: either it is a QCD axion with an associated scale larger than ∼ 105TeV and therefore falling in the category of the invisible axions; or it is a more massive axion-like-particle, such as a 1 GeV axion with an associated scale of ∼ 200 TeV, that may show up in collider searches. ; The authors acknowledge partial financial support by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant agreements No 690575 and No 674896. L.M. acknowledges partial financial support by the Spanish MINECO through the "Ramón y Cajal" programme (RYC-2015- 17173), and by the Spanish "Agencia Estatal de Investigación" (AEI) and the EU "Fondo Europeo deDesarrollo Regional" (FEDER) through the project FPA2016-78645-P, and through the Centro de excelencia Severo Ochoa Program under Grant SEV-2016-0597

Journal of High Energy Physics 2016.4 (2016): 016 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA) ; Artículo escrito por un elevado número de autores, sólo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiera, y los autores pertenecientes a la UAM ; In Alonso et al., JHEP 12 (2014) 034, the CP-even sector of the effective chiral Lagrangian for a generic composite Higgs model with a symmetric coset has been constructed, up to four momenta. In this paper, the CP-odd couplings are studied within the same context. If only the Standard Model bosonic sources of custodial symmetry breaking are considered, then at most six independent operators form a basis. One of them is the weak-θ term linked to non-perturbative sources of CP violation, while the others describe CP-odd perturbative couplings between the Standard Model gauge bosons and an Higgs-like scalar belonging to the Goldstone boson sector. The procedure is then applied to three distinct exemplifying frameworks: the original SU (5) /SO (5) Georgi-Kaplan model, the minimal custodial-preserving SO (5) /SO (4) model and the minimal SU (3) / (SU (2) × U (1)) model, which intrinsically breaks custodial symmetry. Moreover, the projection of the high-energy electroweak effective theory to the low-energy chiral effective Lagrangian for a dynamical Higgs is performed, uncovering strong relations between the operator coefficients and pinpointing the differences with the elementary Higgs scenario ; The work of I.M.H. is supported by an ESR contract of the European Union network FP7 ITN INVISIBLES (Marie Curie Actions, PITN-GA-2011-289442). L.M. acknowledges partial support of the European Union network FP7 ITN INVISIBLES, of CiCYT through the project FPA2012- 31880, of the Spanish MINECO's "Centro de Excelencia Severo Ochoa" Programme under grant SEV-2012-0249, and by a grant from the Simons Foundation. S.R. acknowledges partial support of the European Union network FP7 ITN INVISIBLES and of the COFIN program PRIN 2010. This work was partially performed at the Aspen Center for Physics, which is supported by National Science Foundation grant PHY-1066293

The Higgs-fermion couplings are sensitive probes of possible new physics behind a stable light Higgs particle. It is then essential to identify the flavor pattern of those interactions. We consider the case in which a strong dynamics lies behind a light Higgs and explore the implications within the minimal flavor violation ansatz. The dominant effects on flavor-changing Higgs-fermion couplings stem in this context from operators with mass dimension ≤5, and we analyze all relevant chiral operators up to that order, including loop corrections induced by four-dimensional ones. Bounds on the operator coefficients are derived from a plethora of low-energy flavor transitions, providing a guideline on which flavor-changing Higgs interactions may be open to experimental scrutiny. In particular, the coefficient of a genuinely CP-odd operator is only softly constrained and therefore its impact is potentially interesting ; We acknowledge partial support by European Union FP7 ITN INVISIBLES (Marie Curie Actions, PITN-GA-2011-289442), CiCYT through Project No. FPA2009-09017, CAM through Project No. HEPHACOS P-ESP-00346, European Union FP7 ITN UNILHC (Marie Curie Actions, PITN-GA-2009-237920), MICINN through Grant No. BES-2010-037869 and the Juan de la Cierva program (JCI-2011-09244), ERC Advance Grant ''FLAVOUR'' (267104), Technische Universität München—Institute for Advanced Study—funded by the German Excellence Initiative, Italian Ministero dell'Università e della Ricerca Scientifica through the COFIN program (PRIN 2008) and Contracts No. MRTN-CT-2006-035505 and No. PITN-GA-2009-237920 (UNILHC)

Journal of High Energy Physics 2016.6 (2016): 038 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA) ; In the context of the minimal SO(5) linear σ-model, a complete renormalizable Lagrangian -including gauge bosons and fermions- is considered, with the symmetry softly broken to SO(4). The scalar sector describes both the electroweak Higgs doublet and the singlet σ. Varying the σ mass would allow to sweep from the regime of perturbative ultraviolet completion to the non-linear one assumed in models in which the Higgs particle is a low-energy remnant of some strong dynamics. We analyze the phenomenological implications and constraints from precision observables and LHC data. Furthermore, we derive the d ≤ 6 effective Lagrangian in the limit of heavy exotic fermions ; The authors (each identified by the first letter of her/his last name) acknowledge partial financial support by the European Union through the FP7 ITN INVISIBLES (PITN-GA-2011-289442) (FGKMRS), by the Horizon2020 RISE InvisiblesPlus 690575 (FGKMRS), by CiCYT through the project FPA2012-31880 (GS), and by the Spanish MINECO through the Centro de excelencia Severo Ochoa Program under grant SEV-2012-0249 (GMS). The work of K.K. is supported by an ESR contract of the European Union network FP7 ITN INVISIBLES mentioned above. The work of S.S. is supported through the grant BES-2013-066480 of the Spanish MICINN and she also received support during from the Spanish MICINN grant EEBB-I-15-10242. We would also like to thank the Kavli Institute for Theoretical Physics — Santa Barbara (GM) (National Science Foundation grant PHY11-25915), the Mainz Institute for Theoretical Physics (M), the Physics Department of the University of California San Diego (S), the Aspen Center for Physics (GM) (National Science Foundation grant PHY-1066293 and the Simons Foundation) and the Institute for Theoretical Physics IFT-UAM/CSIC (F) for hospitality and/or partial support during the completion of this work

Journal of High Energy Physics 2013.8 (2013): 069 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA) ; A dynamical origin of the Yukawa couplings is a promising scenario to explain the flavour puzzle. The focus of this letter is set on the role of the neutrino Majorana character: when an O(2)N flavour symmetry acts on the right-handed neutrino sector, the minimum of the scalar potential allows for large mixing angles -in contrast to the simplest quark case- and predicts a maximal Majorana phase. This leads to a strong correlation between neutrino mass hierarchy and mixing pattern. Realistic solutions point to the existence of three heavy right-handed neutrinos ; We acknowledge partial support by European Union FP7 ITN INVISIBLES (Marie Curie Actions, PITNGA-2011-289442), CiCYT through the project FPA2009-09017, CAM through the project HEPHACOS P-ESP-00346, MICINN through the grant BES-2010-037869 and the Juan de la Cierva programme (JCI-2011-09244), Italian Ministero dell'Universitá e della Ricerca Scientifica through the COFIN program (PRIN 2008) and the contracts MRTN-CT-2006- 035505 and PITN-GA-2009-237920 (UNILHC). The authors also acknowledge the support of the Spanish MINECO's "Centro de Excelencia Severo Ochoa" Programme under grant SEV-2012-0249

30 pages, 10 figures, 3 tables.-- Pre-print archive. ; The two dark sectors of the universe—dark matter and dark energy—may interact with each other. Background and linear density perturbation evolution equations are developed for a generic coupling. We then establish the general conditions necessary to obtain models free from non-adiabatic instabilities. As an application, we consider a viable universe in which the interaction strength is proportional to the dark energy density. The scenario does not exhibit ``phantom crossing'' and is free from instabilities, including early ones. A sizeable interaction strength is compatible with combined WMAP, HST, SN, LSS and H(z) data. Neutrino mass and/or cosmic curvature are allowed to be larger than in non-interacting models. Our analysis sheds light as well on unstable scenarios previously proposed. ; The work of M.B.G., D.H. and L.L-H. was partially supported by CICYT through the project FPA2006-05423 and by CAM through the project HEPHACOS, P-ESP-00346. Furthermore, the work of all authors is partially supported by the PAU (Physics of the accelerating universe) Consolider Ingenio 2010. D.H. also acknowledges financial support from the spanish government through a FPU fellowship AP20053603. The work of L.L-H receives financial support through a postdoctoral fellowship of the PAU Consolider Ingenio 2010 and partially through F.M.R.S. and I.I.S.N. The work of O. M. is financially supported by the spanish Ramon y Cajal program. The work of S.R. was partially supported an Excellence Grant of Fondazione Cariparo. ; Peer reviewed

The pattern of deviations from Standard Model predictions and couplings is different for theories of new physics based on a non-linear realization of the SU(2)L × U(1)Y gauge symmetry breaking and those assuming a linear realization. We clarify this issue in a model-independent way via its effective Lagrangian formulation in the presence of a light Higgs particle, up to first order in the expansions: dimension-six operators for the linear expansion and four derivatives for the non-linear one. Complete sets of gauge and gauge-Higgs operators are considered, implementing the renormalization procedure and deriving the Feynman rules for the non-linear expansion. We establish the theoretical relation and the differences in physics impact between the two expansions. Promising discriminating signals include the decorrelation in the non-linear case of signals correlated in the linear one: some pure gauge versus gauge-Higgs couplings and also between couplings with the same number of Higgs legs. Furthermore, anomalous signals expected at first order in the non-linear realization may appear only at higher orders of the linear one, and vice versa. We analyze in detail the impact of both type of discriminating signals on LHC physics. ; We also acknowledge partial support of the European Union network FP7 ITN INVISIBLES (Marie Curie Actions, PITN-GA-2011-289442), of CiCYT through the project FPA2009-09017, of CAM through the project HEPHACOS P-ESP-00346, of the European Union FP7 ITN UNILHC (Marie Curie Actions, PITN-GA- 2009-237920), of MICINN through the grant BES-2010-037869, of the Spanish MINECO's "Centro de Excelencia Severo Ochoa" Programme under grant SEV-2012-0249, and of the Italian Ministero dell'Universit`a e della Ricerca Scientifica through the COFIN program (PRIN 2008) and the contract MRTN-CT-2006-035505. The work of I.B. is supported by an ESR contract of the European Union network FP7 ITN INVISIBLES mentioned above. The work of L.M. is supported by the Juan de la Cierva programme (JCI-2011-09244). The work of O.J.P.E. is supported in part by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and by Funda¸c˜ao de Amparo `a Pesquisa do Estado de S˜ao Paulo (FAPESP), M.C.G-G and T.C are supported by USA-NSF grant PHY-09-6739, M.C.G-G is also supported by CUR Generalitat de Catalunya grant 2009SGR502 and together with J.G-F by MICINN FPA2010-20807 and consolider-ingenio 2010 program CSD-2008-0037. J.G-F is further supported by ME FPU grant AP2009-2546. I.B., J.G-F., M.C.G-G., B.G., L.M, and S.R. acknowledge CERN TH department and J.G-F. also acknowledges ITP Heidelberg for hospitality during part of this work. ; Peer reviewed