A higher-dimensional explanation of the excess of Higgs-like events at CERN LEP

Abstract

Searches for the SM Higgs boson by the four LEP experiments have found a 2.3 σ excess at 98 GeV and a smaller 1.7 σ at around 115 GeV. We interpret these excesses as evidence for a Higgs boson coupled to a higher dimensional singlet scalar. The fit implies a relatively low dimensional mixing scale µ lhd < 50 GeV, which explains the low confidence level found for the background fit in the range s 1/2 > 100 GeV. The data show a slight preference for a fivedimensional over a six-dimensional field. This Higgs boson cannot be seen at the LHC, but can be studied at the ILC.With the latest developments from high energy colliders like LEP and the Tevatron the standard model (SM) has been established up to the loop level. The main missing ingredient is the direct detection of the SM Higgs boson. The four LEP experiments ALEPH, DELPHI, L3 and OPAL have extensively searched for the Higgs boson. The final combined result has been published in [1]. The absence of a clear signal has led to a lower limit on the Higgs boson mass of 114.4 GeV at the 95% confidence level. Although no clear signal was found the data have some intriguing features, that can be interpreted as evidence for Higgs bosons beyond the standard model. There is a 2.3 σ effect seen by all experiments at around 98 GeV. A somewhat less significant 1.7 σ excess is seen around 115 GeV. Finally over the whole range s 1/2 > 100 GeV the confidence level is less than expected from background.Within the minimal supersymmetric standard model (MSSM) and other extensions [2][3][4][5], the excesses at 98 GeV and 115 GeV were interpreted as evi-1

New spectra in the HEIDI Higgs models

“…Another way to analyze the data was presented in [8]. If there is one peak plus a continuum one can do the following.…”

“…In this case we follow the procedure from [8]. We will take the excess at 98 GeV at face value and interpret it as the delta-peak in the propagator.…”

“…In a previous paper [8] these models were compared with the LEP-2 data and it was shown that a good fit was possible, though in a somewhat narrow range of parameters. In this paper we extend the study of [8], by including an extra parameter, a mass term mixing the higher dimensional fields among each other. This extra term would be generated by renormalization effects in any case and should therefore be included when comparing with the data.…”

“…Here m 2 k = m 2 + m 2 γ k 2 , where k is a γ-dimensional vector, m γ = 2π/L and m is a d-dimensional mass term for the field H. This Lagrangian differs from the one in [8] through the presence of the H i H j term. This term however would be present in general, while it is generated via loop effects in the propagator through the Φ † Φ H k interactions.…”

“…It is now straightforward to follow the steps of [8]. One expands around the minimum of the potential and inverts the quadratic part of the Lagrangian, in order to get the propagator.…”