Testing a 95 GeV Scalar at the CEPC with Machine Learning*

Several possible excesses around GeV hint at an additional light scalar beyond the Standard Model. We examine the capability of the Circular Electron-Positron Collider (CEPC) to test this hypothesis in the Higgs-strahlung channel with and . A full detector simulation shows that the optimal center-of-mass energy for studying the 95 GeV light scalar is 210 GeV. A deep neural network classifier reduces the luminosity required for discovery by half. At , the sensitivity of the CEPC to the signal strength reaches 0.016 and 0.020 for GeV and 240 GeV, respectively. The corresponding thresholds for a 5% precision measurement are and . At GeV (240 GeV), the coverage of all N2HDM-Flipped samples with requires (1.22 ). These results establish a 210 GeV run, augmented by machine-learning selection, as the most efficient strategy to confirm or refute the 95 GeV excess at future lepton colliders.