We measured invariant mass spectra of e~+e~- pairs produced in 12-GeV p + A interaction to investigate in-medium mass modification of vector mesons. We observed the excess over the known hadronic sources below the ω meson mass peak. The obtained ρ/ω ratio and velocity dependence of excess/ω ratio imply that this excess mainly results from ρ meson whose mass was modified in nuclear matter.
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机译：我们测量了12-GEV P + A相互作用中产生的E〜+ E〜 - 对的不变质谱，以研究载体胶叶中的中等大量质量修改。我们观察到过量超过ωMESON质量峰以下的已知的辐射源。所获得的ρ/ω比和过量/ω比的速度依赖性意味着这种多余的主要是ρmeson的结果，其质量在核物质中被修改。
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