Abstract
We evaluate the QED corrections due to initial state radiation (ISR) to associated Higgs boson production in electron–positron (e+e−) annihilation at typical energies of interest for the measurement of the Higgs properties at future e+e− colliders, such as CEPC and FCC–ee. We apply the QED Structure Function approach to the four-fermion production process e+e−→μ+μ−bb¯, including both signal and background contributions. We emphasize the relevance of the ISR corrections particularly near threshold and show that finite third order collinear contributions are mandatory to meet the expected experimental accuracy. We analyze in turn the rôle played by a full four-fermion calculation and beam energy spread in precision calculations for Higgs physics at future e+e− colliders.
Highlights
The discovery of a new scalar particle at the LHC in 2012 by the ATLAS [1] and CMS collaborations [2] has opened a new chapter in particle physics, and immediately has triggered the question of the real nature of this boson
The relevance of Initial State Radiation (ISR) QED contributions to associated Higgs boson production, neglected in previous studies, is shown in Fig. 1, where the line shape of the signal process e+e− → ZH → μ+μ−bb in the lowest order approximation (Born) is compared to the corresponding QED corrected cross section (QED) computed according to Eq (1); the relative impact of ISR corrections is shown in the lower panel of Fig. 1
We have provided clear evidence that third order collinear contributions must be taken into account in order to meet the expected experimental accuracy of future Higgs factories
Summary
The discovery of a new scalar particle at the LHC in 2012 by the ATLAS [1] and CMS collaborations [2] has opened a new chapter in particle physics, and immediately has triggered the question of the real nature of this boson. A muon collider Higgs factory [3, 6] could produce the Higgs boson in the s–channel and perform an energy scan to map out the Higgs resonance line shape at tens of MeV level [11] This approach would provide the most direct measurement of the Higgs boson total width, the Yukawa coupling to muons and other fermions, and would enable to investigate the existence of other scalar bosons predicted by natural extensions of the SM.
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