Study of chiral property of nuclear matter based on the dispersion of vector meson.

本课题是完成对KEK-PS-E325实验数据的分析，目的是寻找12 GeV质子-核反应中核物质中矢量介子的谱形变化。这些现象在理论上可以用核介质中手性对称的部分恢复来预测。通过本课题的研究，我们已经完成了对所获得的所有数据的数据分析，并在physics上发表了《12-GeV p + A反应中rho和omega介子介质修饰的实验签名》。启。统计数据高出100倍，再次证实了我们之前的公开结果。我们还首次发现了π介子的修饰，并在《物理学》上发表了论文《首次观察到正常核密度下π介子的介质内修饰》。启。我们还得到了作为横向动量和速度函数的ω和φ介子的绝对产生截面，并在《物理学》上发表了《12-GeV p + A碰撞中ω和φ介子包涵产生的核质量数依赖》一文。这篇论文不是耸人听闻的，但对我们上述发现的基础是非常重要的。我们还比较了介子的K+K衰变和e+e衰变。这一结果对讨论核物质中衰变分支的修饰具有重要意义。这篇论文发表在《物理学》杂志上。启。目前实验的所有目标都已经达到，我们将在不久的将来在全文中总结我们的所有结果。我们认为目前的研究项目已圆满结束，有了新的重要发现。

This research project is to complete the data analyses of the experiment KEK-PS-E325 which has been performed to search for the modification of spectral shape of vector mesons in nuclear matter, in 12 GeV proton-nuclear reactions. Such phenomena are theoretically predicted in term of partial restoration of chiral symmetry in nuclear media.Through the present research project, we have completed the data analyses for all the data we have acquired, and have reported "Experimental signature of the medium modification for rho and omega mesons in 12-GeV p + A reactions" in Phys. Rev. Lett. with 100 times higher statistics and reconfirmed our previous publicafirst results.We have also discovered the modification of phi meson for the first time, and the paper "First observation of in-medium modification of phi meson at normal nuclear density" was published in Phys. Rev. Lett.We have also obtained the absolute production cross section for omega and phi mesons as functions of transverse momentum and rapidity, and the paper the paper "Nuclear mass number dependence of inclusive production of omega and phi mesons in 12-GeV p + A collisions" was published in Phys. Rev. C. This paper is not sensational, but very important to give the basis of our discoveries described above. We have also compared K+K-decays and e+e-decays of phi meson. This result reads to the discussion on the modification of decay branch in nuclear matter. The paper is was published in Phys. Rev. Lett.All the goals of the present experiment have been reached, and we will summarize all our results in the full paper near future. We conclude that the present research project is successfully concluded with new and important discoveries.