Comparing 2HDM + scalar and pseudoscalar simplified models at LHC

Abstract

In this work we compare the current experimental LHC limits of the 2HDM + scalar and pseudoscalar for the tt, mono-Z and mono-h signatures and forecast the reach of future LHC upgrades for the mono-Z channel. Furthermore, we comment on the possibility, in case of a signal detection, to discriminate between the two models. The 2HDM+S and 2HDM+PS are two notable examples of the so-called next generation of Dark Matter Simplified Models. They allow for a renormalizable coupling of fermionic, Standard Model singlet, Dark Matter with a two Higgs doublet sector, through the mixing of the latter with a scalar or pseudoscalar singlet.

The THDMa Revisited

“…In order to guarantee the positivity of the potential, several relations between the potential parameters need to be obeyed (as can be seen, e.g., in [6,12,14]). In the notation introduced here, they are given by…”

“…Furthermore, the models' parameter space is subject to a large number of theoretical and experimental constraints which we will discuss in detail below. Reference [6] contains a detailed discussion as well as benchmark recommendations for the LHC experimental collaborations; these can also be seen in refs [7][8][9][10][11][12][13][14][15] which performed more recent work on this model. Finally, refs [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] report on the experimental constraints of current collider searches on the parameter space in specific parameter regions.…”

On the interplay between astrophysical and laboratory probes of MeV-scale axion-like particles

“…Since the ALP coupling strength to SM particles as well as their precise cosmological history are -1 -JHEP07(2020)050 model-dependent, they have been studied in literature in a wide phenomenological range, e.g. in the context of dark matter [5][6][7][8][9][10][11][12][13][14][15], flavour physics [16][17][18][19][20], astrophysics [21][22][23][24][25][26] and cosmology [27][28][29][30][31][32]. Consequently, there are many experimental efforts to search for different ALP candidates, see e.g.…”

Exploring direct detection suppressed regions in a simple 2-scalar mediator model of scalar dark matter

“…There are, however, many possible variations of this simple picture that can give rise to cancellations in the direct detection cross section. An incomplete list of possibilities appearing in the literature consists of the scalar portal being replaced with a pseudoscalar portal [22,55,[65][66][67][68][69][70][71][72], or having a complex scalar which gives rise to a second scalar portal [20,26,26,57,73,74], a two Higgs doublet model [22,23,55,63,64,[69][70][71][74][75][76][77], higher Higgs representations [78], or supersymmetric models [22,52,54,[79][80][81][82]. Before proceeding, we note that, given that we simply want to push the simplest of models as far as we could, we haven't dealt with the issue of UV completeness.…”