We present a search for the direct production of a light pseudoscalar $a$ decaying into two photons with the Belle II detector at the SuperKEKB collider. We search for the process $e^{+}{e}^{-}\to \gamma a$, $a\to \gamma \gamma$ in the mass range $0.2<m_a<9.7\mathrm{GeV}/c^2$ using data corresponding to an integrated luminosity of $(445\pm 3){\mathrm{pb}}^{-1}$. Light pseudoscalars interacting predominantly with standard model gauge bosons (so-called axionlike particles or ALPs) are frequently postulated in extensions of the standard model. We find no evidence for ALPs and set 95% confidence level upper limits on the coupling strength $g_{a\gamma \gamma }$ of ALPs to photons at the level of ${10}^{-3}{\mathrm{GeV}}^{-1}$. The limits are the most restrictive to date for $0.2<m_a<1\mathrm{GeV}/c^2$.

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搜索在Belle II上产生ine + e-碰撞的轴状粒子

我们提出了寻找直接产生轻伪标量的方法 $\mathrm{一种}$用SuperKEKB对撞机的Belle II探测器衰减成两个光子。我们寻找过程${Ë}^{+}{Ë}^{-}\to \gamma \mathrm{一种}$， $\mathrm{一种}\to \gamma \gamma$ 在质量范围内 $0.2<{米}_{\mathrm{一种}}<9.7\mathrm{GeV}/C^2$ 使用对应于 $（445\pm 3）{铅}^{-\mathrm{1个}}$。通常在标准模型的扩展中假定主要与标准模型规格玻色子（所谓的轴突颗粒或ALP）相互作用的轻拟标量。我们没有找到有关ALP的证据，并为耦合强度设置了95％的置信度上限$G_{\mathrm{一种}\gamma \gamma }$ ALP到光子的水平 ${10}^{-3}{\mathrm{GeV}}^{-\mathrm{1个}}$。该限制是迄今为止对日期最严格的限制$0.2<{米}_{\mathrm{一种}}<\mathrm{1个}\mathrm{GeV}/C^2$。