The anomalous production of multi-leptons and its impact on the measurement of Wh production at the LHC

Yesenia Hernandez,Xifeng Ruan,Bruce Mellado,Yaquan Fang,Alan S Cornell,Salah-Eddine Dahbi,Mukesh Kumar,Kgomotso Monnakgotla,Benjamin Lieberman,Shuiting Xin

doi:10.1140/epjc/s10052-021-09137-1

Abstract

Anomalies in multi-lepton final states at the Large Hadron Collider (LHC) have been reported in Refs. (von Buddenbrock et al., J Phys G 45(11):115003, arXiv:1711.07874 [hep-ph], 2018; Buddenbrock et al., JHEP 1910:157, arXiv:1901.05300 [hep-ph], 2019). These can be interpreted in terms of the production of a heavy boson, H, decaying into a standard model (SM) Higgs boson, h, and a singlet scalar, S, which is treated as a SM Higgs-like boson. This process would naturally affect the measurement of the Wh signal strength at the LHC, where h is produced in association with leptons and di-jets. Here, h would be produced with lower transverse momentum, p_{Th}, compared to SM processes. Corners of the phase-space are fixed according to the model parameters derived in Refs. (von Buddenbrock et al., J Phys G 45(11):115003, arXiv:1711.07874 [hep-ph], 2018; von Buddenbrock et al., Eur Phys J C 76(10):580, arXiv:1606.01674 [hep-ph], 2016) without additional tuning, thus nullifying potential look-else-where effects or selection biases. Provided that no stringent requirements are made on p_{Th} or related observables, the signal strength of Wh is mu (Wh)=2.41 pm 0.37. This corresponds to a deviation from the SM of 3.8sigma . This result further strengthens the need to measure with precision the SM Higgs boson couplings in e^+e^-, and e^-p collisions, in addition to pp collisions.

Highlights

The discovery of a Higgs boson (h) [4,5,6,7] at the Large Hadron Collider (LHC) by the ATLAS [8] and CMS [9] experiments has opened a new chapter in particle physics
Measurements provided so far indicate that the quantum numbers of this boson are consistent with those predicted by the Standard Model (SM) [10,11], and that the relative branching ratios (BRs) to SM particles follow what is predicted by the SM
While this paper focuses on the anomalous production of the SM Higgs boson in association with leptons, it is relevant to investigate if these findings do not contradict measurement of inclusive observables made by the experiments

Summary

Introduction

The discovery of a Higgs boson (h) [4,5,6,7] at the Large Hadron Collider (LHC) by the ATLAS [8] and CMS [9] experiments has opened a new chapter in particle physics. Measurements provided so far indicate that the quantum numbers of this boson are consistent with those predicted by the Standard Model (SM) [10,11], and that the relative branching ratios (BRs) to SM particles follow what is predicted by the SM With this in mind, a window of opportunity opens for the search for new bosons and how these would affect the h boson measurements. [12] the impact on the measurement of the process H → Sh was evaluated in final states including h → γ γ in association with hadronic jets. The paper is organised as follows: Sect. 2 succinctly describes the simplified model used to model the BSM signal described above; Sect. 3 reports on the available data and the methodology used to study it; Sect. 4 points to the compatibility of the results with the measurements of inclusive observables made by the experiments; Sect. 5 summarises the findings of the paper and quantifies the size of the observed anomaly in the Higgs boson data

The simplified model

Methodology

Pythia8

Results and conclusions