库仑田对几个GEV重型离子碰撞中带电的pion光谱的影响

论文标题

库仑田对几个GEV重型离子碰撞中带电的pion光谱的影响

Impact of the Coulomb field on charged-pion spectra in few-GeV heavy-ion collisions

论文作者

Adamczewski-Musch, J., Arnold, O., Behnke, C., Belounnas, A., Belyaev, A., Berger-Chen, J. C., Blanco, A., Blume, C., Böhmer, M., Bordalo, P., Chernenko, S., Chlad, L., Ciepał, I., Deveaux, C., Dreyer, J., Epple, E., Fabbietti, L., Fateev, O., Filip, P., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Galatyuk, T., Garzon, J. A., Gernhäuser, R., Golubeva, M., Greifenhagen, R., Guber, F., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Hlavac, S., Höhne, C., Holzmann, R., Ierusalimov, A., Ivashkin, A., Kämpfer, B., Karavicheva, T., Kardan, B., Koenig, I., Koenig, W., Kohls, M., Kolb, B. W., Korcyl, G., Kornakov, G., Kornas, F., Kotte, R., Kugler, A., Kunz, T., Kurepin, A., Kurilkin, A., Kurilkin, P., Ladygin, V., Lalik, R., Lapidus, K., Lebedev, A., Linev, S., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Mangiarotti, A., Markert, J., Matulewicz, T., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Morozov, S., Müntz, C., Münzer, R., Nabroth, M., Naumann, L., Nowakowski, K., Parpottas, Y., Parschau, M., Pechenov, V., Pechenova, O., Petukhov, O., Piasecki, K., Pietraszko, J., Przygoda, W., Pysz, K., Ramos, S., Ramstein, B., Rathod, N., Reshetin, A., Rodriguez-Ramos, P., Rosier, P., Rost, A., Rustamov, A., Sadovsky, A., Salabura, P., Scheib, T., Schuldes, H., Schild, N., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Selyuzhenkov, I., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Sobolev, Yu. G., Spataro, S., Spies, S., Ströbele, H., Stroth, J., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Usenko, E., Wagner, V., Wendisch, C., Wiebusch, M. G., Wirth, J., Zanevsky, Y., Zumbruch, P.

论文摘要

在核碰撞中，入射质子产生的库仑场作用于产生的带电颗粒。这些相互作用对带电的Pion横向质量和速度光谱以及对Pion-Pion动量相关性的影响在$ \ sqrt {s_ {nn}} $ = 2.4 GEV的AU+AU碰撞中进行了研究。我们表明，可以用库仑修饰的玻尔兹曼分布来很好地描述数据的低MT部分（$ M_T <0.2 $ GEV/C $^2 $），在考虑到火球扩展期间，该库仑的Boltzmann发行版也可以更改库仑场。拟合平均库仑电势的观察到的中心性依赖性与$ a_ {part}^{2/3} $缩放强烈偏离，表明必须考虑到火球旁边，必须考虑非交互带电的观众。对于最中心的碰撞，发现HBT源半径的库仑修饰与从单杆横质量分布中提取的电势一致。这一发现表明，从两杆子相关性获得的同质性区域与促旋流冻结的区域一致。使用冻结时电荷分布的推断均方根半径，我们推断了重子密度，这与从统计强化模型获得的值符合粒子产量的值。

In nuclear collisions the incident protons generate a Coulomb field which acts on produced charged particles. The impact of these interactions on charged pion transverse-mass and rapidity spectra, as well as on pion-pion momentum correlations is investigated in Au+Au collisions at $\sqrt{s_{NN}}$ = 2.4 GeV. We show that the low-mt part of the data ($m_t < 0.2$ GeV/c$^2$) can be well described with a Coulomb-modified Boltzmann distribution that also takes changes of the Coulomb field during the expansion of the fireball into account. The observed centrality dependence of the fitted mean Coulomb potential deviates strongly from a $A_{part}^{2/3}$ scaling, indicating that, next to the fireball, the non-interacting charged spectators have to be taken into account. For the most central collisions, the Coulomb modifications of the HBT source radii are found to be consistent with the potential extracted from the single-pion transverse-mass distributions. This finding suggests that the region of homogeneity obtained from two-pion correlations coincides with the region in which the pions freeze-out. Using the inferred mean-square radius of the charge distribution at freeze-out, we have deduced a baryon density, in fair agreement with values obtained from statistical hadronization model fits to the particle yields.

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