Pion decay constant

In particle physics, the pion decay constant is the square root of the coefficient in front of the kinetic term for the pion in the low-energy effective action. It is dimensionally an energy scale and it determines the strength of the chiral symmetry breaking. The values are:

f_{\pi^{\pm}} = 130.41 \pm 0.03 \pm 0.20~\mbox{MeV}
f_{\pi^{0}} = 130 \pm 5~\mbox{MeV}

Beware: There are several conventions which differ by powers of \scriptstyle \sqrt{2}. The textbook by Weinberg uses the value 184 MeV. The textbook by Peskin and Schroeder uses the value 93 MeV.

References

  1. Particle Data Group: W.-M. Yao et al., J. Phys. G 33, 1 (2006).
  2. Griffiths, David J. (1987). Introduction to Elementary Particles. Wiley, John & Sons, Inc. ISBN 0-471-60386-4.
  3. Particle Data Group: Decay constants of charged pseudoscalar mesons

External links

  1. Particle Data Group & WWW edition of Review of Particle Physics