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Gunion J.F.,University of California at Davis | Jiang Y.,University of California at Davis | Kraml S.,CNRS Laboratory of Subatomic Physics & Cosmology
Physical Review Letters | Year: 2013

We develop diagnostic tools that would provide incontrovertible evidence for the presence of more than one Higgs boson near 125 GeV in the LHC data. © 2013 American Physical Society.


Gunion J.F.,University of California at Davis | Jiang Y.,University of California at Davis | Kraml S.,CNRS Laboratory of Subatomic Physics & Cosmology
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

We assess the extent to which various constrained versions of the NMSSM are able to describe the recent hints of a Higgs signal at the LHC corresponding to a Higgs mass in the range 123-128 GeV. © 2012 Elsevier B.V.


Gunion J.F.,University of California at Davis | Jiang Y.,University of California at Davis | Kraml S.,CNRS Laboratory of Subatomic Physics & Cosmology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We examine next-to-minimal supersymmetric model scenarios with partial parameter unification at the grand unification scale in which both h 1 and h 2 lie in the 123-128 GeV mass range. Very substantially enhanced γγ and other rates are possible. Broadened mass peaks are natural. © 2012 American Physical Society.


Klempt E.,University of Bonn | Richard J.-M.,CNRS Laboratory of Subatomic Physics & Cosmology | Richard J.-M.,University Claude Bernard Lyon 1
Reviews of Modern Physics | Year: 2010

About 120 baryons and baryon resonances are known, from the abundant nucleon with u and d light-quark constituents up to the Ξb- = (bsd), which contains one quark of each generation and to the recently discovered Ωb- = (bss). In spite of this impressively large number of states, the underlying mechanisms leading to the excitation spectrum are not yet understood. Heavy-quark baryons suffer from a lack of known spin parities. In the light-quark sector, quark-model calculations have met with considerable success in explaining the low-mass excitations spectrum but some important aspects such as the mass degeneracy of positive-parity and negative-parity baryon excitations remain unclear. At high masses, above 1.8 GeV, quark models predict a very high density of resonances per mass interval which is not yet observed. In this review, issues are identified discriminating between different views of the resonance spectrum; prospects are discussed on how open questions in baryon spectroscopy may find answers from photoproduction and electroproduction experiments which are presently carried out in various laboratories. © 2010 The American Physical Society.


Ashtekar A.,Pennsylvania State University | Barrau A.,CNRS Laboratory of Subatomic Physics & Cosmology
Classical and Quantum Gravity | Year: 2015

The Planck collaboration has provided us rich information about the early Universe, and a host of new observational missions will soon shed further light on the 'anomalies' that appear to exist on the largest angular scales. From a quantum gravity perspective, it is natural to inquire if one can trace back the origin of such puzzling features to Planck scale physics. Loop quantum cosmology provides a promising avenue to explore this issue because of its natural resolution of the big bang singularity. Thanks to advances over the last decade, the theory has matured sufficiently to allow concrete calculations of the phenomenological consequences of its pre-inflationary dynamics. In this article we summarize the current status of the ensuing two-way dialog between quantum gravity and observations. © 2015 IOP Publishing Ltd.


Fichet S.,Federal University of Rio Grande do Norte | Fichet S.,CNRS Laboratory of Subatomic Physics & Cosmology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We present a formulation of naturalness made in the framework of Bayesian statistics, which unravels the conceptual problems related to previous approaches. Among other things, the relative interpretation of the measure of naturalness turns out to be unambiguously established by Jeffreys' scale. Also, the usual sensitivity formulation (the so-called Barbieri-Giudice measure) appears to be embedded in our formulation under an extended form. We derive the general sensitivity formula applicable to an arbitrary number of observables. Several consequences and developments are further discussed. As a final illustration, we work out the map of combined fine-tuning associated with the gauge hierarchy problem and neutralino dark matter in a classic supersymmetric model. © 2012 American Physical Society.


Parattu K.M.,Inter-University Center for Astronomy and Astrophysics | Wingerter A.,CNRS Laboratory of Subatomic Physics & Cosmology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

Current experimental data on the neutrino parameters are in good agreement with tribimaximal mixing and may indicate the presence of an underlying family symmetry. For 76 flavor groups, we perform a systematic scan for models: The particle content is that of the standard model plus up to three flavon fields, and the effective Lagrangian contains all terms of mass dimension ≤6. We find that 44 groups can accommodate models that are consistent with experiment at 3σ, and 38 groups can have models that are tribimaximal. For A 4×Z3, T7, and T13 we look at correlations between the mixing angles and make a prediction for θ13 that will be testable in the near future. We present the details of a model with θ12=33.9°, θ23=40. 9°, θ13=5.1° to show that the recent tentative hints of a nonzero θ13 can easily be accommodated. The smallest group for which we find tribimaximal mixing is T7. We argue that T 7 and T13 are as suited to produce tribimaximal mixing as A4 and should therefore be considered on equal footing. In the appendixes, we present some new mathematical methods and results that may prove useful for future model building efforts. © 2011 American Physical Society.


Linsefors L.,CNRS Laboratory of Subatomic Physics & Cosmology | Barrau A.,CNRS Laboratory of Subatomic Physics & Cosmology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Loop quantum cosmology with a scalar field is known to be closely linked with an inflationary phase. In this article, we study probabilistic predictions for the duration of slow-roll inflation, by assuming a minimalist massive scalar field as the main content of the Universe. The phase of the field in its "prebounce" oscillatory state is taken as a natural random parameter. We find that the probability for a given number of inflationary e-folds is quite sharply peaked around 145, which is consistent with the most favored minimum values. In this precise sense, a satisfactory inflation is therefore a clear prediction of loop gravity. In addition, we derive an original and stringent upper limit on the Barbero-Immirzi parameter. The general picture of inflation, superinflation, deflation, and superdeflation is also much clarified in the framework of bouncing cosmologies. © 2013 American Physical Society.


Bernon J.,CNRS Laboratory of Subatomic Physics & Cosmology | Smith C.,CNRS Laboratory of Subatomic Physics & Cosmology
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

The recently observed diphoton anomaly at the LHC appears to suggest the presence of a rather broad resonance. In this note, it is pointed out that this broadness is not called for if the two photons are produced along with an extra state. Specifically, the diphoton invariant mass arising from various A→. Bγγ processes, with A, B being scalars, fermions, or vectors, though peaked at a rather large value, would naturally be broad and could fit rather well the observed deviations. This interpretation has a number of advantages over the two-photon resonance hypothesis, for example with respect to the compatibility with the 8 TeV diphoton, dilepton or dijet searches, and opens many new routes for New Physics model construction. © 2016 The Authors.


Wingerter A.,CNRS Laboratory of Subatomic Physics & Cosmology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

We revisit the stability and triviality bounds on the Higgs boson mass in the context of the standard model with three and four generations (SM3 and SM4, respectively). In light of the recent results from LHC, the triviality bound in the SM3 has now become obsolete, and the stability bound implies for a Higgs mass of e.g. mH=115GeV the onset of new physics before Λ=650TeV, whereas there are no limits for mH 133GeV. For the SM4, the stability and triviality curves intersect and bound a finite region. As a consequence, the fourth generation fermions place stringent theoretical limits on the Higgs mass, and there is a maximal scale beyond which the theory cannot be perturbatively valid. We find that the Higgs mass cannot exceed 700 GeV for any values of the fourth generation fermion masses. Turning the argument around, the absence of a Higgs signal for mH≤600GeV excludes a fourth generation with quark masses below 300 GeV and lepton masses below 350 GeV. In particular, the quark bounds also hold for the small mixing scenarios for which the direct limits from Tevatron and LHC are not applicable, and the lepton bounds we obtain are stronger than the collider limits. If a Higgs boson lighter than 700 GeV is not observed, a fourth generation of chiral fermions with perturbative Yukawa couplings will be conclusively excluded for the full range of parameters. © 2011 American Physical Society.

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