Testing minimal universal extra dimensions using Higgs boson searches at the LHC

Abstract

Large Hadron Collider (LHC) searches for the SM Higgs boson provide a powerful limit on models involving Universal Extra Dimensions (UED) where the Higgs production is enhanced. We have evaluated all one-loop diagrams for Higgs production gg → h and decay h → γγ within "minimal" UED (mUED), independently confirming previous results, and we have evaluated enhancement factors for Higgs boson production and decay over the mUED parameter space. Using these we have derived limits on the parameter space, combining data from both ATLAS and CMS collaborations for the most recent 7 TeV and 8 TeV LHC data. We have performed a rigorous statistical combination of several Higgs boson search channels which is important because mUED signatures from the Higgs boson are not universally enhanced.We have found that R −1 < 500 GeV is excluded at 95% CL, while for larger R −1 only a very narrow (±1−4 GeV) mass window around m h = 125 GeV and another window (up to 2 GeV wide for R −1 > 1000 GeV) around m h = 118 GeV are left. The latter is likely to be excluded as more data becomes available whereas the region around m h = 125 GeV is where the recently discovered Higgs-like particle was observed and therefore where the exclusion limit is weaker.It is worth stressing that mUED predicts an enhancement for all channels for gg → h production and decay while the vector boson fusion process W W/ZZ → h → γγ is generically suppressed and W W/ZZ → h → W W * /ZZ * is standard. Therefore, as more 8 TeV LHC data becomes available, the information on individual Higgs boson production and decay processes provided by the CMS and ATLAS experiments can be effectively used to favour mUED or exclude it further.2

Hydrogen atom in space with a compactified extra dimension and potential defined by Gauss’ law

“…Because R crit was found to be of the order of the Bohr radius, we did not obtain a stronger constraint on models involving one extra dimension, as the latest calculations based on the LHC data, cf. [17] and also [18,19,20], give the value of about 10 −18 m as the upper bound. In more detail, the lower bound on the compactification scale R −1 obtained at 3σ and coming from the LEP collider precision electroweak tests is about R −1 > 260GeV.…”

A review on non-minimal universal extra dimensions

“…UED models predict an enhanced Higgs production rate via gluon fusion as well as a modified decay rate for h → γγ because the top KK modes and (for the decay) W KK modes contribute to these one-loop induced processes [36,38,39]. Within the minimal UED model, the current ATLAS and CMS Higgs measurements [40,41] imply a lower bound of R −1 460GeV (from ATLAS data) and R −1 1300GeV (from CMS data) [42].…”

Constraining compressed versions of MUED and MSSM using soft tracks at the LHC

“…When subjected to the constraint regarding the observed value of the relic density measurement of the recent Planck data [41], it immediately puts a strong bound on the radius of compactification as [42] 1.40 TeV R −1 1.46 TeV. (2.4) Various collider signatures of MUED have been studied extensively over many years [43][44][45][46][47][48][49]. One usually looks for missing transverse energy (coming from LKP) accompanied by decay products from KK particles in the cascade.…”