Suchergebnisse

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

We extend the coverage of resonant di-Higgs searches in the bb¯ bb¯ final state to the process pp → H1→ H2H2→ bb¯ bb¯ , where both H1,2 are spin-0 states beyond the Standard Model. Such a process constitutes a joint discovery mode for the new states H1 and H2. We present the first sensitivity study of this channel, using public LHC data to validate our analysis. We also provide a first estimate of the sensitivity of the search for the HL-LHC and future facilities like the HE-LHC and FCC-hh. We analyze the discovery potential of this search for several non-minimal scalar sector scenarios: an extension of the SM with two extra singlet scalar fields, the two-Higgs-doublet model and a two-Higgs doublet model plus a singlet, which captures the scalar potential features of the NMSSM. We find that this channel represents a novel, very powerful probe for extended Higgs sectors, offering complementary sensitivity to existing analyses ; K.M. is supported in part by the F.R.S.-FNRS under the Excellence of Science EOS be.h project n. 30820817 and by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 707983. J.M.N. was partially supported by the Programa Atracción de Talento de la Comunidad de Madrid under grant 2017-T1/TIC-5202, and by Ramón y Cajal Fellowship contract RYC-2017-22986. J.M.N also acknowledges support from the Spanish MINECO's "Centro de Excelencia Severo Ochoa" Programme under grant SEV-2016-0597, from the European Union's Horizon 2020 research and innovation programme under the Marie SklodowskaCurie grant agreements 690575 (RISE InvisiblesPlus) and 674896 (ITN ELUSIVES) and from the Spanish Proyectos de I+D de Generación de Conocimiento via grant PGC2018- 096646-A-I00. C.V. is supported by the SLAC Panofsky Fellowship. D.B. thanks the Galileo Galilei Institute for theoretical physics for hospitality while part of this work was carried out. J.M.N. thanks the Korean Institute for Advanced Study (KIAS) for hospitality during the last stages of this work

We consider the three dimensional electrodynamics described by a complex scalar field coupled with the U(1) gauge field in the presence of a Maxwell term, a Chern-Simons term and the Higgs potential. The Chern-Simons term provides a velocity dependent gauge potential and the presence of the Maxwell term makes the U(1) gauge field dynamical. We study the Hamiltonian formulation of this Maxwell-Chern-Simons-Higgs theory under the appropriate gauge fixing conditions.

In this work we explore the sensitivity to the Higgs self-coupling λ in the production of two Higgs bosons via vector boson scattering at the LHC. Although these production channels, concretely W+W−→HH and ZZ→HH, have lower rates than gluon-gluon fusion, they benefit from being tree level processes, being independent of top physics and having very distinctive kinematics that allow us to obtain very clean experimental signatures. This makes them competitive channels concerning the sensitivity to the Higgs self-coupling. In order to give predictions for the sensitivity to this coupling, we first study the role of λ at the subprocess level, both in and beyond the Standard Model, to move afterwards to the LHC scenario. We characterize the pp→HHjj case first and then provide quantitative results for the values of λ that can be probed at the LHC in vector boson scattering processes after considering the Higgs boson decays. We focus mainly on pp→bb¯bb¯jj, since it has the largest signal rates, and also comment on the potential of other channels, such as pp→bb¯γγjj, as they lead to cleaner, although smaller, signals. Our whole study is performed for a center of mass energy of s=14TeV and for various future expected LHC luminosities ; This work is supported by the European Union through the ITN ELUSIVES H2020-MSCA-ITN-2015//674896 and the RISE INVISIBLESPLUS H2020-MSCA-RISE-2015//690575, by the CICYT through the projects FPA2016-78645-P, by the Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042) and by the Spanish MINECO's "Centro de Excelencia Severo Ochoa" Programme under grant SEV-2016-0597. This work has also been partially supported by CONICET and ANPCyT projects no. PICT 2016-0164 and no. PICT-2017-2765 (E.A.)

Large mass splittings between new scalars in two-Higgs-doublet models (2HDM) open a key avenue to search for these new states via exotic heavy Higgs decays. We discuss in detail the different search channels for these new scalars at the LHC in the presence of a sizable mass splitting, i.e. a hierarchical 2HDM scenario, taking into account the theoretical and experimental constraints. We provide benchmark planes to exploit the complementarity among these searches, analyzing their potential to probe the hierarchical 2HDM parameter space during LHC Run 2. ; Munich Institute for Astro- and Particle Physics (MIAPP) of the DFG cluster of excellence "Origin and Structure of the Universe"; US Department of Energy [DE-FG02-04ER-41298]; Fermilab Graduate Student Research Program in Theoretical Physics; United States Department of Energy [DE-AC02-07CH11359]; European Union [PIEF-GA-2013-625809] ; Open Access Journal. ; This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.

Journal of High Energy Physics 2015.9 (2015): 210 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA) ; The measured values of the Higgs and top quark masses imply that the Standard Model potential is very likely to be unstable at large Higgs values. This is particularly problematic during inflation, which sources large perturbations of the Higgs. The instability could be cured by a threshold effect induced by a scalar with a large vacuum expectation value and directly connected to the Standard Model through a Higgs portal coupling. However, we find that in a minimal model in which the scalar generates inflation, this mechanism does not stabilize the potential because the mass required for inflation is beyond the instability scale. This conclusion does not change if the Higgs has a direct weak coupling to the scalar curvature. On the other hand, if the potential is absolutely stable, successful inflation in agreement with current CMB data can occur along a valley of the potential with a Mexican hat profile. We revisit the stability conditions, independently of inflation, and clarify that the threshold effect cannot work if the Higgs portal coupling is too small. We also show that inflation in a false Higgs vacuum appearing radiatively for a tuned ratio of the Higgs and top masses leads to an amplitude of primordial gravitational waves that is far too high, ruling out this possibility ; GB thanks Perimeter Institute for hospitality at the very beginning of this work. Research at Perimeter Institute is supported in part by the Government of Canada through Industry Canada, and by the Province of Ontario through the Ministry of Research and Information (MRI). GB thanks as well the Departament de Física Fondamental at the Universitat de Barcelona and the CERN Theory Division for hospitality at different stages of this work. CT acknowledges support of the Spanish Government through grant FPA2011-24568 (MICINN), and thanks Rhorry Gauld and Anupam Mazumdar for useful conversations. GB thanks Brando Bellazzini, Alberto Casas, Mikael Chala, José Ramón Espinosa, Mathias Garny, Gian Giudice and Felix Kahlhoefer for valuable discussions and comments on a draft version of this work. We also thank Isabella Masina and Alessio Notari for useful exchanges

A new Higgs-like boson with mass around 126 GeV has recently been discovered at the LHC. The available data on this new particle is analyzed within the context of two-Higgs doublet models without tree-level flavour-changing neutral currents. Keeping the generic Yukawa structure of the Aligned Two-Higgs Doublet Model framework, we study the implications of the LHC data on the allowed scalar spectrum. We analyze both the CP-violating and CP-conserving cases, and a few particular limits with a reduced number of free parameters, such as the usual models based on discrete Z(2) symmetries. ; We are grateful to Luca Fiorini for discussions about the experimental data. This work has been supported in part by the Spanish Government and ERDF funds from the EU Commission [grants FPA2007-60323, FPA2011-23778 and CSD2007-00042 (Consolider Project CPAN)]. The work of A. C. is funded through an FPU grant (AP2010-0308, MINECO, Spain). ; Peer reviewed

In July 2012, the two experiments ATLAS and CMS, operating at the CERN proton-proton collider LHC, announced the discovery of a new particle consistent with the Higgs boson. This observation confirms a key prediction of the Standard Model of particle physics, that the Universe is pervaded by a field which conveys mass to the elementary constituents of matter. This paper reviews the experimental effort which led to such a result, and the challanges that had to be overcome during the conception and constuction of LHC and its experiments, the most powerful accelerator and the most complex detectors ever built. Finally, the nature and role of CERN and the meaning and impact of fundamental research are briefly discussed.

Journal of High Energy Physics 2016.4 (2016): 141 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA) ; The Higgs portal to scalar Dark Matter is considered in the context of nonlinearly realised electroweak symmetry breaking. We determine the dominant interactions of gauge bosons and the physical Higgs particle h to a scalar singlet Dark Matter candidate. Phenomenological consequences are also studied in detail, including the possibility of distinguishing this scenario from the standard Higgs portal in which the electroweak symmetry breaking is linearly realised. Two features of significant impact are: i) the connection between the electroweak scale v and the Higgs particle departs from the (v + h) functional dependence, as the Higgs field is not necessarily an exact electroweak doublet; ii) the presence of specific couplings that arise at different order in the non-linear and in the linear expansions. These facts deeply affect the Dark Matter relic abundance, as well as the expected signals in direct and indirect searches and collider phenomenology, where Dark Matter production rates are enhanced with respect to the standard portal ; The work of K.M. and V.S. is supported by the Science Technology and Facilities Council (STFC) under grant number ST/L000504/1. I.B. research was supported by an ESR contract of the EU network FP7 ITN INVISIBLES (Marie Curie Actions, PITN-GA-2011-289442). I.B., M.B.G., L.M., R.dR. acknowledge partial support of the European Union network FP7 ITN INVISIBLES, of CiCYT through the project FPA2012-31880 and of the Spanish MINECO's "Centro de Excelencia Severo Ochoa" Programme under grant SEV-2012-0249. M.B.G. and L.M. acknowledge partial support by a grant from the Simons Foundation and the Aspen Center for Physics, where part of this work has been developed, which is supported by National Science Foundation grant PHY-1066293. J.M.N. is supported by the People Programme (Marie Curie Actions) of the European Union Seventh Framework Programme (FP7/2007-2013) under REA grant agreement PIEF-GA-2013-625809

An important task at future colliders is the measurement of the triple Higgs coupling. Depending on its size relative to the Standard Model (SM) value, certain collider options result in a higher experimental accuracy. Within the framework of Two Higgs Doublet Models (2HDM) types I and II we investigate the allowed ranges for all triple Higgs couplings involving at least one light, SM-like Higgs boson. We take into account theoretical constraints (unitarity, stability), experimental constraints from direct Higgs-boson searches, measurements of the SM-like Higgs-boson properties, flavor observables and electroweak precision data. We find that the SM-type triple Higgs coupling w.r.t. its SM value, λhhh/λSM, can range between ∼−0.5 and ∼1.5. Depending on which value is realized, the HL-LHC can compete with, or is clearly inferior to the ILC. We find the coupling λhhH between ∼−1.5 and ∼1.5. Triple Higgs couplings involving two heavy Higgs bosons, λhHH, λhAA and λhH+H− can reach values up to O(10), roughly independent of the 2HDM type. This can lead to potentially strongly enhanced production of two Higgs-bosons at the HL-LHC or high-energy e+e− colliders. ; The present work has received financial support from the 'Spanish Agencia Estatal de Investigación" (AEI) and the EU "Fondo Europeo de Desarrollo Regional" (FEDER) through the project FPA2016-78022-P and from the grant IFT Centro de Excelencia Severo Ochoa SEV-2016-0597. The work of S.H. was also supported in part by the MEINCOP Spain under contract FPA2016-78022-P and in part by the "Spanish Red Consolider MultiDark" FPA2017-90566-REDC. This work has also received partial funding/support from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 674896. The work of F.A. was also supported by the Spanish Ministry of Science and Innovation via a FPU grant with code FPU18/06634. ; Funded by SCOAP3. ; Peer reviewed