Scalar-isoscalar mesons in pion production at threshold

Abstract

We present the contributions of the non-linear chiral scalar field S to cross sections of $pp\to d{\pi }^{+},pp\to pn{\pi }^{+}$ and $pp\to pp{\pi }^0$ reactions at threshold. We compare our results with the meson $\sigma$ contribution from the $\sigma$-linear model. We show that the chiral scalar field S is almost 5 times bigger than the other contributions, which indicates that the two-pion exchange dynamics embebbed in the S field is the most important term for the pion production at threshold.

Comments: Non-relativistic approximations added, one new table inserted