Temperature effects on the electromagnetic couplings of pions in hot hadronic matter are studied with an effective chiral Lagrangian. We show that the Ward-Takahashi identity is satisfied at non-zero temperature in the soft pion limit. The in-medium electromagnetic form factor of the pion is obtained in the time-like region and shown to be reduced in magnitude, especially near the vector-meson ...

The Standard Model prediction for the magnetic moment of the muon requires a determination of the electromagnetic form factor of the pion at high precision. It is shown that the recent progress in ππ scattering allows us to obtain an accurate representation of this form factor on the basis of the data on e+e− → π+π−. The same method also applies to the form factor of the weak vector current, wh...

The electromagnetic form factor of the pion in the space-like region, and at finite temperature, Fπ(Q 2, T ), is obtained from a QCD Finite Energy Sum Rule. The form factor decreases with increasing T, and vanishes at some critical temperature, where the pion radius diverges. This divergence may be interpreted as a signal for quark deconfinement. John Simon Guggenheim Fellow 1994-1995 The possi...

We calculate the electromagnetic pion form factor at intermediate spacelike momentum transfer from the QCD sum rule for the correlation function of two pseudoscalar interpolating fields and the electromagnetic current. This correlator receives essential contributions from direct (i.e. small-scale) instantons, which we evaluate under the assumption of an instanton size distribution consistent wi...