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تسجيل مستخدم جديدNew results on multiplicity, identified particles and spin measurements in e+e- collisions
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تأليف
Vasilii Nomokonov
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The analyses of recent LEP data provide us with a rich ground for pQCD and LPHD tests. A number of non-trivial effects predicted in the framework of MLLA are experimentally verified. Recent measurements also enrich our knowledge about the hadronization process.
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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 ${e^+e^-togamma a, a togammagamma}$ in the mass range ${0.2} ,< m_a <
{9.7},{text{GeV/$c$}^2}$ using data corresponding to an integrated luminosity of $(445pm 3),text{pb}^{-1}$. Light pseudoscalars interacting predominantly with standard model gauge bosons (so-called axion-like 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 $g_{agammagamma}$ of ALPs to photons at the level of $10^{-3},{text{GeV}^{-1}}$. The limits are the most restrictive to date for $0.2,<,m_a,<,1,{text{GeV/$c$}^2}$.
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