Abstract
We study discovery prospects for a real triplet extension of the Standard Model scalar sector at the Large Hadron Collider (LHC) and a possible future 100 TeV pp collider. We focus on the scenario in which the neutral triplet scalar is stable and contributes to the dark matter relic density. When produced in pp collisions, the charged triplet scalar decays to the neutral component plus a soft pion or soft lepton pair, yielding a disappearing charged track in the detector. We recast current 13 TeV LHC searches for disappearing tracks, and find that the LHC presently excludes a real triplet scalar lighter than 248 (275) GeV, for a mass splitting of 172 (160) MeV with ℒ = 36 fb−1. The reach can extend to 497 (520) GeV with the collection of 3000 fb−1. We extrapolate the 13 TeV analysis to a prospective 100 TeV pp collider, and find that a ∼ 3 TeV triplet scalar could be discoverable with ℒ = 30 ab−1, depending on the degree to which pile up effects are under control. We also investigate the dark matter candidate in our model and corresponding present and prospective constraints from dark matter direct detection. We find that currently XENON1T can exclude a real triplet dark matter lighter than ∼ 3 TeV for a Higgs portal coupling of order one or larger, and the future XENON20T will cover almost the entire dark matter viable parameter space except for vanishingly small portal coupling.
Highlights
(Y = 0), which is the simplest extension of the SM scalar sector involving particles carrying electroweak charge
We find that currently XENON1T can exclude a real triplet dark matter lighter than ∼ 3 TeV for a Higgs portal coupling of order one or larger, and the future XENON20T will cover almost the entire dark matter viable parameter space except for vanishingly small portal coupling
When the triplet is heavy, which is relevant for our DM study as detailed below, since the gluon-gluon fusion process (ggF) process will be suppressed as discussed above, the most relevant NLO QCD corrections are those applicable to the electroweak Drell-Yan process.√As summarized in ref. [43], the corresponding Kfactor is about 1.18 for the Large Hadron Collider (LHC) with s = 13 TeV, which corresponds to mild corrections to our leading order (LO) results
Summary
With the Higgs vacuum expectation value (VEV) v 246 GeV. The covariant derivative acting on Σ is defined by DμΣ = ∂μΣ + ig2 [Wμ, Σ] with the product of the SU(2) gauge boson and Pauli matrices Wμ = Wμaτ a/2 (the corresponding expression for DμH is standard). In the case of m0 mW , the above expression can be simplified, leading to ∆m = (166 ± 1) MeV This mass splitting ensures the decay channel Σ± → Σ0π± is kinematically allowed, and the corresponding rate is. Where the other quantities in this expression are the Fermi constant GF , pion decay constant fπ (= 131 MeV), the CKM matrix Vud and pion mass mπ.1 This decay mode accounts for 98% of the branching ratio, and the remaining modes are Σ± → Σ0μ±νμ and Σ± → Σ0e±νe. In the presence of the Higgs portal coupling, an additional production mechanism, gluon-gluon fusion process (ggF ) in the right diagram of figure 2, can increase the number of disappearing track events. In what follows, including the ggF process, we analyze the reach with disappearing track searches, including a mass range for mΣ0 consistent with the observed relic density
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