Probing Higgs-radion mixing in warped models through complementary searches at the LHC and the ILC (original) (raw)

Mixed Higgs–radion states at the LHC – a detailed study

Nuclear Physics B

Light radions constitute one of the few surviving possibilities for observable new particle states at the sub-TeV level which arise in models with extra spacetime dimensions. It is already known that the 125 GeV state discovered at CERN is unlikely to be a pure radion state, since its decays resemble those of the Standard Model Higgs boson too closely. However, due to experimental errors in the measured decay widths, the possibility still remains that it could be a mixture of the radion with one (or more) Higgs states. We use the existing LHC data at 8 and 13 TeV to make a thorough investigation of this possibility. Not surprisingly, it turns out that this model is already constrained quite effectively by direct LHC searches for an additional scalar heavier than 125 GeV. We then make a detailed study of the so-called 'conformal point', where this heavy state practically decouples from (most of) the Standard Model fields. Some projections for the future are also included.

Radion-Higgs mixing effects on bounds from LHC Higgs boson searches

Physical Review D, 2012

The radion, a scalar particle associated with the radius of a compact warped extra dimension, may be the lightest new particle in this class of models. Its couplings to SM particles are proportional to the their masses, similar to the usual Higgs boson, but suppressed by a scale à r , the radion vacuum expectation value. The main differences are the coupling to massless gauge bosons that receives contribution from the trace anomaly of the energy-momentum tensor due to the nonvanishing functions and the mixing with the Higgs boson arising from a nonminimal coupling to gravity parametrized by a dimensionless coefficient. In particular, these differences can result in significant modifications of the radion phenomenology. We use current LHC data on Higgs searches to find exclusion regions on the parameters of a radion model, à r , and the radion mass m r. We find that, even for low values of à r , the radion can still have a mass in the region where the Standard Model Higgs has been excluded, for a narrow range of values for the mixing parameter. Some signals at the LHC for this scenario are discussed. We also find that it is possible to hide the Higgs boson in the current searches in this model, due to a suppression of its couplings.

Radion and Higgs mixing at the LHC

Physics Letters B, 2002

We study the resonance production of radions and Higgs via gluon-gluon fusion in the Randall-Sundrum model with Higgs-curvature mixing at the LHC. We find that radion can be detected both in mixed (with Higgs boson) and unmixed case if the radion vacuum expectation value Λ φ is around 1 TeV. The Λ φ ∼ 10 TeV case is also promising for certain values of mixing parameters and radion masses. The mixing can affect the production and decay of Higgs boson in a significant way. Thus Higgs search strategies at the LHC may need refinements in case of radion-Higgs mixing in the Randall-Sundrum model.

Effects of Radion Mixing on the Standard Model Higgs Boson

2002

We discuss how mixing between the Standard Model Higgs boson and the radion of the Randall-Sundrum model can lead to significant shifts in the expected properties of the Higgs boson. In particular we show that the total and partial decay widths of the Higgs, as well as the h → gg branching fraction, can be substantially altered from their SM expectations, while the remaining branching fractions are modified less than about 5% for most of the parameter space volume. Precision measurements of Higgs boson properties at at a Linear Collider are shown to probe a large region of the Randall-Sundrum model parameter space.

O ct 2 00 3 HIP-2003-35 / TH hep-ph / yymmddd Hunting Radions at Linear Colliders

2003

We investigate the possibility to disentangle the radions in the Randall-Sundrum scenario from higgs boson at the next generation high energy ee linear colliders. Due to trace anomaly, the radion coupling (and in turn the branching ratio) to gluons is enhanced over the same for the Standard Model (SM) higgs. We study the radion φ production at electron-positron colliders, via the process ee → νν̄φ, and propose to investigate radion decay to a pair of gluons. At 500 GeV center of mass energy, our signal is not very promising. We find our results are encouraging for finding radion and differentiating it from higgs for center of mass energies of 1 TeV and above. Recently proposed models [1, 2], aiming to cure the hierarchy problem between electroweak (EW) and Planck scale, offer an exciting possibility to test the gravitational interactions at the TeV colliders. The models in [1, 2] require our universe to have (3 + n) + 1 space-time dimensions, of which the extra, n, space-like dimens...

Constraining hypothetical extensions to the Higgs sector at the LHC

2019

With Run 2 of the LHC currently under way at a record-breaking centre of mass energy of 13 TeV, new physics searches are becoming more feasible than ever before. In particular, the ATLAS and CMS collaborations are beginning to focus more on searches which may extend the Higgs sector of the Standard Model. Here it is shown that Run 1 data from both ATLAS and CMS hint at the existence of a new heavy scalar with a mass around 270 GeV. This work will also extend this idea by introducing a full Two-Higgs Doublet Model and outlining the potential Run 2 searches which could constrain the parameters of such a model, should it exist in nature. This will be presented in the context of searches for Higgs production in association with missing energy, leptons and large jet multiplicities. Some preliminary studies related to the rates and kinematic distributions of processes of interest are presented and their implications are discussed in the context of the ATLAS Z+MET search.

Probing intermediate mass Higgs interactions at the CERN large hadron collider

Physics Letters B, 2000

We analyze the potentiality of the CERN Large Hadron Collider to probe the Higgs boson couplings to the electroweak gauge bosons. We parametrize the possible deviations of these couplings due to new physics in a model independent way, using the most general dimension-six effective lagrangian where the SU (2) L ⊗ U (1) Y is realized linearly. For intermediate Higgs masses, the decay channel into two photons is the most important one for Higgs searches at the LHC. We study the effects of these new interactions on the Higgs production mechanism and its subsequent decay into two photons. We show that the LHC will be sensitive to new physics scales beyond the present limits extracted from the LEP and Tevatron physics.