Publications [#349849] of Haiyan Gao

Papers Published

1. Larin, I; Zhang, Y; Gasparian, A; Gan, L; Miskimen, R; Khandaker, M; Dale, D; Danagoulian, S; Pasyuk, E; Gao, H; Ahmidouch, A; Ambrozewicz, P; Baturin, V; Burkert, V; Clinton, E; Deur, A; Dolgolenko, A; Dutta, D; Fedotov, G; Feng, J; Gevorkyan, S; Glamazdin, A; Guo, L; Isupov, E; Ito, MM; Klein, F; Kowalski, S; Kubarovsky, A; Kubarovsky, V; Lawrence, D; Lu, H; Ma, L; Matveev, V; Morrison, B; Micherdzinska, A; Nakagawa, I; Park, K; Pedroni, R; Phelps, W; Protopopescu, D; Rimal, D; Romanov, D; Salgado, C; Shahinyan, A; Sober, D; Stepanyan, S; Tarasov, VV; Taylor, S; Vasiliev, A; Wood, M; Ye, L; Zihlmann, B; PrimEx-II Collaboration, Precision measurement of the neutral pion lifetime., Science (New York, N.Y.), vol. 368 no. 6490 (May, 2020), pp. 506-509 (This high-impact paper presents the world most precise measurement of the neutral pion lifetime, and provides one of the most important tests of low-energy QCD. This paper reports on the thesis work of Duke graduate student Yang Zhang that I supervised. I contributed to the data analysis and the writing of the paper. The published version originated from the earlier version that Yang and I drafted..) [doi] [high impact paper]
   (last updated on 2026/01/14)

   Author's Comments:
   This paper reports on the thesis work of Duke graduate student Yang Zhang that I supervised. I contributed to the data analysis and the writing of the paper. The published version originated from the earlier version that Yang and I drafted.

   Abstract:
   The explicit breaking of the axial symmetry by quantum fluctuations gives rise to the so-called axial anomaly. This phenomenon is solely responsible for the decay of the neutral pion π⁰ into two photons (γγ), leading to its unusually short lifetime. We precisely measured the decay width Γ of the [Formula: see text] process. The differential cross sections for π⁰ photoproduction at forward angles were measured on two targets, carbon-12 and silicon-28, yielding [Formula: see text], where stat. denotes the statistical uncertainty and syst. the systematic uncertainty. We combined the results of this and an earlier experiment to generate a weighted average of [Formula: see text] Our final result has a total uncertainty of 1.50% and confirms the prediction based on the chiral anomaly in quantum chromodynamics.