Symmetry energy investigation with pion production from Sn+Sn systems
Creators: name: Jhang, G.
name: Estee, J.
name: Barney, J.
name: Cerizza, G.
name: Kaneko, M.
name: Lee, J. W.
name: Lynch, W. G.
name: Isobe, T.
name: Kurata-Nishimura, M.
name: Murakami, T.
name: Tsang, C. Y .
name: Tsang, M. B.
name: Wang, R.
name: Ahn, D. S.
name: Atar, L.
name: Aumann, T.
name: Baba, H.
name: Boretzky, K.
name: Brzychczyk, J.
name: Chiga, N.
name: Fukuda, N.
name: Gasparic, I.
name: Hong, B.
name: Horvat, A.
name: Ieki, K.
name: Inabe, N.
name: Kim, Y. J.
name: Kobayashi, T.
name: Kondo, Y.
name: Lasko, P.
name: Lee, H. S.
name: Leifels, Y.
name: Łukasik, J.
name: Manfredi, J.
name: McIntosh, A. B.
name: Morfouace, P.
name: Nakamura, T.
name: Nakatsuka, N.
name: Nishimura, S.
name: Olsen, R.
name: Otsu, H.
name: Pawłowski, P.
name: Pelczar, K.
name: Rossi, D.
name: Sakurai, H.
name: Santamaria, C.
name: Sato, H.
name: Scheit, H.
name: Shane, R.
name: Shimizu, Y.
name: Simon, H.
name: Snoch, A.
name: Sochocka, A.
name: Sosin, Z.
name: Sumikama, T.
name: Suzuki, H.
name: Suzuki, D.
name: Takeda, H.
name: Tangwancharoen, S.
name: Toernqvist, H.
name: Togano, Y.
name: Xiao, Z. G.
name: Yennello, S. J.
name: Yurkon, J.
name: Zhang, Y.
name: Colonna, Maria
name: Cozma, Dan
name: Danielewicz, Paweł
name: Elfner, Hannah
name: Ikeno, Natsumi
name: Ko, Che Ming
name: Mohs, Justin
name: Oliinychenko, Dmytro
name: Ono, Akira
name: Su, Jun
name: Wang, Yong Jia
name: Wolter, Hermann
name: Xu, Jun
name: Zhang, Ying-Xun
name: Zhang, Zhen
Publisher: name: arXiv
Year: 2020
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: In the past two decades, pions created in the high density regions of heavy ion collisions have been predicted to be sensitive at high densities to the symmetry energy term in the nuclear equation of state, a property that is key to our understanding of neutron stars. In a new experiment designed to study the symmetry energy, the multiplicities of negatively and positively charged pions have been measured with high accuracy for central $^{132}$Sn+$^{124}$Sn, $^{112}$Sn+$^{124}$Sn, and $^{108}$Sn+$^{112}$Sn collisions at $E/A=270~\mathrm{MeV}$ with the S$π$RIT Time Projection Chamber. While the uncertainties of individual pion multiplicities are measured to 4\%, those of the charged pion multiplicity ratios are measured to 2\%. We compare these data to predictions from seven major transport models. The calculations reproduce qualitatively the dependence of the multiplicities and their ratios on the total neutron to proton number in the colliding systems. However, the predictions of the transport models from different codes differ too much to allow extraction of reliable constraints on the symmetry energy from the data. This finding may explain previous contradictory conclusions on symmetry energy constraints obtained from pion data in Au+Au system. These new results call for better understanding of the differences among transport codes, and new observables that are more sensitive to the density dependence of the symmetry energy.
description: 8 pages, 4 figures, 1 table (accepted for publication in PLB)