Direct measurement of the Higgs self-coupling in e+e− → ZH

Junya Nakamura,Ambresh Shivaji

doi:10.1016/j.physletb.2019.134821

Abstract

A new method to measure the trilinear Higgs self-coupling λ3 in a single Higgs production process is proposed. Time-reversal-odd (T-odd) asymmetries in the process e+e−→ZH, Z→ff¯ are computed from the absorptive part of the electroweak one-loop amplitude. Since the T-odd asymmetries measure the tree-level t-channel ZH→ZH scattering, they can be direct probes of λ3. The proposed method is quite challenging; a relatively large statistics and polarized e+e− beams are demanded. However, this is probably the only approach to directly measure λ3 in e+e− collisions, when a beam energy above the ZHH production threshold is not available.

Highlights

A new method to measure the trilinear Higgs self-coupling λ3 in a single Higgs production process is proposed
Unlike the couplings of the Higgs bosons with heavy fermions and gauge bosons, we do not have any meaningful information on λ3 and its value can be very different from the one predicted in the standard model (SM)
The measurements from the di-Higgs production processes, which are commonly referred as direct measurements, are challenging, because of their very small cross sections both at the LHC [1, 2, 4, 5, 9, 10, 15, 21] and at e+e− colliders [3, 6, 7, 17, 22], at which a relatively high beam energy is required

Summary

Introduction

A new method to measure the trilinear Higgs self-coupling λ3 in a single Higgs production process is proposed. The measurements from the di-Higgs production processes, which are commonly referred as direct measurements, are challenging, because of their very small cross sections both at the LHC [1, 2, 4, 5, 9, 10, 15, 21] and at e+e− colliders [3, 6, 7, 17, 22], at which a relatively high beam energy is required. The information on λ3 may be obtained from measurement of the (differential) cross sections of the single Higgs production processes [8, 11–14, 16–18, 22, 23, 27].

Results

Conclusion