Measurement of the HZγ coupling at the future linear e+e- collider

We examine the prospects for measuring the HZgamma coupling of a standard model-like Higgs boson with a mass between 120 and 160 GeV at the future TESLA linear e(+)e(-) collider, assuming an integrated luminosity of 1 ab(-1) and a center-of-mass energy of 500 GeV. We consider the Higgs boson produced in association with nu(e)(ν) over bar (e) via the W W fusion reaction e(+)e(-) --> nu(e)(ν) over bar H-e, followed by the rare decay into a Z boson and a photon, H --> Zgamma. Accounting for all main background contributions, a precision of 27% can be achieved in unpolarized e(+)e(-) collisions for M-H = 140 GeV. With appropriate initial state polarisations DeltaBF(H --> Zgamma)/BF( H --> Zgamma), or the precisions on the H --> Zgamma partial width, can be improved to 17% and provide valuable information on the HZgamma coupling. For M-H = 120 and 160 GeV, the small significance of the signals in unpolarized collisions sets upper limits of 79% respectively 72% at 90% confidence level on the H-->Zgamma branching fraction.