Dip or nothingness of a Higgs resonance from the interference with a complex phase

Abstract

We show that new resonance shapes -a pure dip, nothingness and an enhanced pure peakcan be produced from the interference between resonance and continuum with a relative phase. Production conditions of those new shapes are derived based on a general parameterization of the interference. The narrow width approximation is modified to work with the non-zero imaginary part of interference, and the correction factor can characterize the resonance shape. We demonstrate that the new resonance shapes of heavy Higgs bosons, H 0 and A 0 in the Type II aligned two Higgs doublet model, generally show up in gg → H 0 /A 0 → tt as well as bb and γγ channels. The pure A 0 resonance dip in the tt channel is a particularly interesting signal as it can be probed well by the current search techniques that do not even take into account interferences; the high-luminosity LHC 14 TeV can perhaps probe a large part of its parameter space.

Scalar production and decay to top quarks including interference effects at NLO in QCD in an EFT approach

“…[21,22] and in more detail in refs. [23][24][25][26]. It appears to receive similar QCD corrections, as indicated by estimates in an effective field theory (EFT) approach in the soft gluon approximation [27], and in a simplified K-factor derived from the geometric mean of the background and signal K-factors [28].…”

“…It has been noticed in an earlier work [22], and discussed in a series of recent works [25,26,28,[48][49][50][51][52], that the production of a heavy scalar resonance leads to large interference with the SM tt background. This large interference could be further augmented by a nontrivial relative phase between the signal and the SM background amplitude, possibly leading to more complicated structures.…”

“…This large interference could be further augmented by a nontrivial relative phase between the signal and the SM background amplitude, possibly leading to more complicated structures. Possible lineshapes can vary from a pure Breit-Wigner (BW) resonance to peak-dip structures, pure dip structures, and even enhanced-peak structures, depending on the details of the underlying model [25].…”

“…For example, in the 2HDM, the heavy scalar and pseudoscalar couple to the gluons through top-quark loops. In this case the phase starts to appear as the mass of the resonance goes above the 2m t threshold, possibly leading to pure dip or enhanced peak structures [25].…”

Isolating top contributions in the production of the 750 GeV diphoton excess

“…Such a dependence will make the conclusion weaker. Second, it has been well known that the "peak" in the tt invariant mass spectrum from this process is suffered by the interference effect with the SM top-pair production [150][151][152][153][154]. This interference effect will smear the "peak" and make the discovery of the signal very difficult at the LHC, especially for the φ which is heavier than 700GeV.…”