Les Houches

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Responsible: Ken Mimasu

Members: Jose Mi No, Chris Pollard, Sanjoy Biswas, Adam Falkowski

Idea

Can we see heavy Higgs bosons with masses above the ttbar threshold decaying into top pairs about the large continuum QCD background?

Things to take into account:

• The overwhelming size of said QCD background
• Large interference effects between signal and (t-channel mediated) background, producing a peak-dip structure

Literature

http://arxiv.org/abs/hep-ph/9404359

One of the earlier papers discussing this channel. They quantify the peak-dip structure of the signal and emphasise the fact that, depending on the heavy Higgs mass, the total cross section can be reduced, enhanced or stay roughly the same as the SM value. They conclude that the effect may potentially be observed at the LHC is the ttbar mass resolution is smaller than the width of the top, as we discussed.

http://arxiv.org/abs/1503.01656

Maltoni et al. implementation of HZ production in Madgraph5_aMC@NLO. The ZH production cross section looks to be O(1) fb in their benchmark scenarios what take masses of 350, 440 and 500 GeV. This is to be compared with a recent calculation by Frixione et al. (http://arxiv.org/abs/1504.03446) of the background ttZ process at LO quoting O(500) fb cross sections.