The Improvement On The Calculation Of Low-Energy Constants

Chiral perturbation theory, in which the chiral effective Lagrangian has already been expanded by momentum orders, provides a feasible way to describe the strong interaction of the low-energy microscopic particles. However, as the fact that the low-energy constants are unknown under the theory, now, how to obtain them has become one of the research hotspots in the chiral perturbation theory. The newly-developed techniques have been able to calculate the all low-energy constants, but the errors are not very small. In order to make the technique more accurately to determine all the low-energy constants, we should ensure the differences between the new p4 order results and experiment data as mall as possible.In order to achieve these purposes, we attempt to find where the large error come from through two aspects below:first we suspect the errors is caused by the ultraviolet cutoff A appearing in the calculation, and we introduce another method which can avoid the problem to calculate the p4 order low-energy constants again, but the obtained result in the two flavors cannot consistent with the correspond experiment values. The errors can also be come from the formula of the chiral effective action, because of the formula is obtained by neglecting some terms. We consider the contributions in the leading order of some terms. Obtained the p4 and p6 results can indeed closer the experiment data than old ones.