Abstract
The associated production of Higgs boson with a hard photon at lepton collider, i.e., e+e−→Hγ, is known to bear a rather small cross section in Standard Model, and can serve as a sensitive probe for the potential new physics signals. Similar to the loop-induced Higgs decay channels H→γγ,Zγ, the e+e−→Hγ process also starts at one-loop order provided that the tiny electron mass is neglected. In this work, we calculate the next-to-leading-order (NLO) QCD corrections to this associated H+γ production process, which mainly stem from the gluonic dressing to the top quark loop. The QCD corrections are found to be rather modest at lower center-of-mass energy range (s<300 GeV), thus of negligible impact on Higgs factory such as CEPC. Nevertheless, when the energy is boosted to the ILC energy range (s≈400 GeV), QCD corrections may enhance the leading-order cross section by 20%. In any event, the e+e−→Hγ process has a maximal production rate σmax≈0.08 fb around s=250 GeV, thus CEPC turns out to be the best place to look for this rare Higgs production process. In the high energy limit, the effect of NLO QCD corrections become completely negligible, which can be simply attributed to the different asymptotic scaling behaviors of the LO and NLO cross sections, where the former exhibits a milder decrement ∝1/s , but the latter undergoes a much faster decrease ∝1/s2.
Highlights
After the historical discovery of the 125 GeV boson by the ATLAS and CMS collaborations at LHC in 2012 [1, 2], a great amount of efforts have been devoted to unravelling its nature
The leading order (LO) predictions for the production rate of e+e− → Hγ in Standard Model (SM) are rather small at the next-generation e+e− colliders, which may render it a sensitive probe for the elusive beyond-SM signals
In this Letter, we have, for the first time, calculated the NLO QCD corrections to this associated H + γ production process, and conducted a comprehensive numerical study covering a wide range of CM energy
Summary
After the historical discovery of the 125 GeV boson by the ATLAS and CMS collaborations at LHC in 2012 [1, 2], a great amount of efforts have been devoted to unravelling its nature. Three promising next-generation e+e− colliders, International Linear Collider (ILC) in Japan [4, 5], Future Circular Collider (FCC-ee) at CERN [6] (formerly called TLEP), and Circular Electron-Positron Collider (CEPC) in China [7, 8], have been proposed in recent years All these three e+e− colliders plan to operate at center-of-mass (CM) energy around 250 GeV, where the dominant Higgs production channel is via the so-called Higgsstrahlung process, e+e− → HZ. For this reason, these e+e− machines are collectively referred to as Higgs factory. For the convenience of the readers, the compact expressions for the LO amplitude are collected in Appendix
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