Search for soft unclustered energy patterns in association with a massive vector boson in proton-proton collisions at 13 TeV

A search for soft unclustered energy patterns (SUEPs) produced in association with a massive vector boson is presented. This search extends existing SUEP searches by probing the previously inaccessible case of a scalar mediator with a mass of 125 GeV, using 138 fb^-1 of proton-proton collision data collected at √s=13 TeV, with the CMS experiment at the LHC. SUEPs are predicted by Hidden Valley models with a new, confining force with a large 't Hooft coupling, resulting in a spray of low-momentum, isotropically distributed particles. These characteristics are used in events with a vector boson recoiling against the SUEP candidate to reject the Standard Model (SM) background. The remaining backgrounds in the signal region are estimated using the data-driven extended-ABCD method. The signal-enriched region is fit alongside multiple signal-depleted regions in data, to constrain uncertainties. The large phase space of SUEPs produced from a 125 GeV scalar mediator will be tightly constrained using both the W and Z associated production channels. A model-agnostic framework is also presented for the re-interpretation of these results.