arXiv subjects

J. J. van der Bij

Publications and source records attributed to J. J. van der Bij.

65 records · Page 4Linked to original sources

arXiv1997

Nonperturbative Higgs propagator: NLO correction in the 1/N expansion

We derive a nonperturbative result for the Higgs propagator by calculating the NLO correction in the 1/N expansion of O(N) sigma models. For dealing with the 1/N expansion beyond leading order, we develop techniques to calculate certain infinite sets of multiloop Feynman diagrams. We then calculate the Higgs lineshape in fermion scattering, as seen for instance at a muon collider. We compare with the existing two-loop perturbative results. There is a considerable discrepancy between perturbation theory and the 1/N expansion in LO. By including the NLO correction, this discrepancy is reduced dramatically. The results are in very good agreement with the two-loop result even for masses as high as 850 GeV. A maximum of the mass is reached at 930 GeV. For phenomenological purposes, we give a simple approximate relation between the Higgs mass and width.

hep-ph↗

arXiv1996

Influence of strongly coupled, hidden scalars on Higgs signals

To investigate the possible effects of a light hidden sector on Higgs boson detection, we discuss a model of scalar singlets coupled to the Standard Model. The model effectively makes the Higgs width a free parameter due to additional invisible decay modes. This width can become arbitrarily large. Theoretical and experimental bounds on model parameters are presented. It is shown, how Standard Model predictions change and that in the case of large coupling, Higgs signals will be diluted. We study, to which extent such a strongly coupled, hidden sector can be excluded by present and future Higgs search experiments.

hep-ph↗

arXiv1996

The hidden Higgs model at the NLC

We investigate the influence of massless scalar singlets on Higgs signals at the NLC. An exclusion bound is presented which restricts large regions of the parameter space but on the other hand implies that for strong interactions between the Higgs boson and the singlet fields of the hidden sector, detection of such a non standard Higgs signal can become impossible.

hep-ph↗

arXiv1995

The hidden Higgs model at LEP2

The influence of massless scalar singlets on the Higgs signal at LEP2 is discussed. It is shown that for strong interactions between the Higgs boson and the singlet fields, detection of the Higgs signal can become impossible.

hep-ph↗

arXiv1995

The Higgs resonance shape in gluon fusion: Heavy Higgs effects

We study the influence of two--loop radiative corrections of enhanced electroweak strength on Higgs production at the LHC. We consider Higgs production by the gluon fusion mechanism, with the subsequent decay of the Higgs boson into a pair of Z bosons, and incorporate the resonance shape corrections up to order $(g^2 \, m_H^2 / m_W^2)^2$. We take into account the full $g g \rightarrow Z Z$ process and the $q \bar{q} \rightarrow Z Z$ background, as well as the subsequent decay of the Z pair into leptons. We also discuss the theoretical uncertainty related to the use of the equivalence theorem in this process.

hep-ph↗

arXiv1995

An axially-symmetric Newtonian Boson Star

A new solution to the coupled gravitational and scalar field equations for a condensed boson field is found in Newtonian approximation. The solution is axially symmetric, but not spherically symmetric. For N particles the mass of the object is given by $M = Nm - 0.02298 N^3 G_N^2 m^5$, to be compared with $M = Nm - 0.05426 N^3 G_N^2 m^5$ for the spherically symmetric case.

astro-ph↗

arXiv1995

Can gravity play a role at the electroweak scale?

A connection is made between a model for strongly interacting vector bosons and the spontaneously broken theory of gravity. The theory contains effectively no Higgs particle, but should have strong interactions at the electroweak scale. Some speculations about the nature of these interactions and possible experimental signatures are discussed.

hep-ph↗

arXiv1994

Massive two--loop diagrams: The Higgs propagator

Formulae are provided to express any two-loop scalar integral with arbitrary masses and arbitrary external momenta in terms of an integral of one fairly simple function or of its derivatives. Such integrals can be calculated numerically with high precision. Good agreement is found with known analytical expressions of specific two--loop diagrams. To prove the effectiveness of these techniques, the two--loop selfenergy of the Higgs boson to order $(g^{2} \frac{m_{H}^{2}}{m_{W}^{2}})^{2}$ is calculated, and the correctness of the result is checked by using the unitarity of the S matrix. This result allows one to disentangle the leading corrections to the shape of the Higgs resonance, and to derive a perturbative bound of $\sim$1.2 TeV on the mass of the Higgs boson.

hep-ph↗

arXiv1994

Leptonic Signals from off-shell Z Boson Pairs at Hadron Colliders

We study the gluon fusion into pairs of off-shell Z bosons and their subsequent decay into charged lepton pairs at hadron colliders. We do not restrict the intermediate state Z bosons to the narrow width approximation but allow for arbitrary invariant masses. We compare the strength of this process with the known leading order results for q q_bar -> Z Z -> 4 l and for g g -> H -> Z Z -> 4 l .

hep-ph↗

arXiv1993

The Hill Theorem

It is studied how strong interactions in the Higgs sector can lead to deviations in vector boson selfcouplings. Normally such effects are small due to Veltman's screening theorem. It is shown that strong interactions are possible, if there is a hierarchy of strong interactions in the Higgs sector. This is called Hill's theorem.

hep-ph↗

arXiv1993

Can gravity make the Higgs particle light?

The spontaneous symmetry breaking theory of gravity is examined, assuming that the vacuum expectation value of the standard model Higgs is also responsible for the generation of the Planck mass. In this model the physical Higgs couples only with gravitational strength to matter. At presently accessible energies the theory is indistinguishable from the standard model without Higgs boson and is in agreement with all existing data.At energies above the Fermi scale new dynamics should occur.

hep-th↗