Search for low mass vector resonances decaying into quark-antiquark pairs in proton-proton collisions at s=13  TeV

Abstract

A search for low mass narrow vector resonances decaying into quark-antiquark pairs is presented. The analysis is based on data collected in 2017 with the CMS detector at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 41.1 fb −1. The results of this analysis are combined with those of an earlier analysis based on data collected at the same collision energy in 2016, corresponding to 35.9 fb −1. Signal candidates will be recoiling against initial state radiation and are identified as energetic, large-radius jets with two pronged substructure. The invariant jet mass spectrum is probed for a potential narrow peaking signal over a smoothly falling background. No evidence for such resonances is observed within the mass range of 50-450 GeV. Upper limits at the 95% confidence level are set on the coupling of narrow resonances to quarks, as a function of the resonance mass. For masses between 50 and 300 GeV these are the most sensitive limits to date. This analysis extends the earlier search to a mass range of 300-450 GeV, which is probed for the first time with jet substructure techniques.

Asymmetric heavy-quark hadroproduction at LHCb: predictions and applications

“…One sees that for the parameters (5.6) only Z bosons with masses in the range M Z ∈ [108, 135] GeV , (5.8) are compatible with the LHCb measurements of Z → bb production at the 95% CL. In fact, the minimum of ∆χ 2 is located at M Z 120 GeV in close proximity to the local excess in the CMS measurement [66] observed for dijet masses around 115 GeV. The corresponding χ 2 /dof is 1.9 and thus slightly better than the SM fit which leads to χ 2 /dof = 2.0.…”

“…For the benchmark parameters (5.5) the combination of the constraints [66][67][68] can however be shown to be fulfilled for most of the Z -boson masses in (5.7). In fact, the search [66] features an 2.9σ local excess for dijet invariant masses around 115 GeV, which has been interpreted in [63] as a Z boson in the U (1) D model with M Z 115 GeV and (5.6). In the following, we point out that Z boson with the properties (5.6) and (5.7), can also be probed by the LHCb measurement of Z → bb production in the forward direction [17].…”

“…As pointed out in [63], the presence of a Z boson in this mass range is subject to several constraints. The first constraint comes from the CMS search [66] for narrow spin-1 resonances decaying to a qq pair in association with a high-transverse momentum jet from ISR. Other relevant constraints arise from the Z → + − searches [67,68].…”

“…Other relevant constraints arise from the Z → + − searches [67,68]. For the benchmark parameters (5.5) the combination of the constraints [66][67][68] can however be shown to be fulfilled for most of the Z -boson masses in (5.7). In fact, the search [66] features an 2.9σ local excess for dijet invariant masses around 115 GeV, which has been interpreted in [63] as a Z boson in the U (1) D model with M Z 115 GeV and (5.6).…”

Higgs bosons with large couplings to light quarks

“…For second-Higgs doublet masses, m H 300 GeV, the best collider constraints come from searches for the boosted topologies at the LHC [85,89,90]. In this work we recast the CMS limits presented in ref.…”