Forschung im HLRN-Verbund 2011

161Higgs boson mass bounds [GeV ]70060050040030020010005001000 1500 2000 25003000Cutoff Λ [GeV ]Figure 1: The final result on the Higgs boson mass bounds. The solid lines are predictions from perturbation theory;the red curve denotes the effect of three fermion generations with a physical top quark mass of 175 GeVand a physical bottom quark mass of 4.2 GeV.removed (it assumes an infinitely large value) theself-interaction vanishes completely and leaves atrivial, non-interacting theory behind. Therefore, itonly makes sense to study the theory with a cut-offin place and to investigate the dependence of theHiggs boson mass bounds as a function of the cutoff.This cut-off dependence is the main result ofour work and it is shown in fig. 1.In our model, there are mass-less modes whichlead to large finite size effects of physical quantities.We have therefore performed a careful analysisof these effects by performing simulations onvarious size lattices up to 40 4 number of points.Hence we have about O(10 Million) degrees offreedom in the problem. The data shown in fig. 1are then obtained after an extrapolation to an infinitevolume is performed.In fig. 1, the area between the lower and the upperHiggs boson mass bounds gives directly theallowed range of Higgs boson masses consistentwith the electroweak standard model. However, thegraph can also be interpreted in an alternative way:if we assume that the Higgs boson mass has beendetermined experimentally at the LHC, we can directlyread off the maximal value of the cut-off upto which the standard model is valid. For example,if the Higgs boson mass would be found at around600 GeV, the maximal cut-off is about 1.5 TeV. Realizingthat the value of the cut-off is just a measurefor the scale where new physics beyond the standardmodel has to appear, such a scenario wouldlead then to the exciting conclusion that a new kindof physics will be detected at the LHC.We conclude this contribution by mentioning thatwe presently investigate the resonance parametersof the Higgs boson which will provide additional informationon the Higgs sector and which is anotherimportant information for Higgs boson searches atthe LHC. In addition, we are looking at effects of apossible heavy 4th quark generation on the Higgsboson mass bounds. First results [4] indicate thatwhile the upper Higgs boson mass bound is onlyshifted by about 20%, the lower mass bound isshifted almost by a factor of ten. This can providevery stringent bounds on the mass of such a heavynew fermion generation.More Information1. P. Gerhold, K. Jansen, Lower Higgs boson massbounds from a chirally invariant lattice Higgs-Yukawa model with overlap fermions, JHEP0907 (2009) 025.2. P. Gerhold, K. Jansen, Upper Higgs bosonmass bounds from a chirally invariant latticeHiggs-Yukawa model, JHEP 1004 (2010) 094.3. P. Gerhold, Upper and lower Higgs bosonmass bounds from a chirally invariant latticeHiggs-Yukawa model, PhD Thesis, HU Berlin,[arXiv:1002.2569 [hep-lat]].4. P. Gerhold, K. Jansen, J. Kallarackal,Higgs boson mass bounds in the presenceof a very heavy fourth quark generation,[arXiv:1011.1648 [hep-lat]], to appear in JHEP.FundingGerman Research Foundation (DFG), TelekomFoundationPhysik