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...

J. P. Lees, V. Poireau, E. Prencipe, V. Tisserand, J. Garra Tico, E. Grauges, M. Martinelli, A. Palano, M. Pappagallo, G. Eigen, B. Stugu, L. Sun, M. Battaglia, D.N. Brown, B. Hooberman, L. T. Kerth, Yu. G. Kolomensky, G. Lynch, I. L. Osipenkov, T. Tanabe, C.M. Hawkes, N. Soni, A. T. Watson, H. Koch, T. Schroeder, D. J. Asgeirsson, C. Hearty, T. S. Mattison, J. A. McKenna, M. Barrett, A. Khan, ...

If you are uncertain about the meaning of the terms “quadratic form” or “linear form”, definitions will appear in Section 2. Interestingly enough, this problem has a simple solution, and was answered several centuries ago. However, many people we talked to found it intriguing and were surprised they had not thought about or seen this problem before. A solution will be a part of what we present ...

Logarithmically enhanced effects due to radiation of soft gluons at large angles in 2 → 2 QCD scattering processes are treated in terms of the ”fifth form factor” that accompanies the four collinear singular Sudakov form factors attached to incoming and outgoing hard partons. Unexpected symmetry under exchange of internal and external variables of the problem is pointed out for the anomalous di...

We find the leading order result for the anapole form factor of the deuteron using effective field theory. The momentum dependence of the anapole form factor is different from that of the matrix element of the strange currents in the deuteron, which may provide a way for disentangling these two competing effects when analyzing parity violating electron-deuteron scattering experiments. We give c...

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...

We analyze within a semiclassical approximation the form factor for the fluctuations of quantum matrix elements around their classical average. We find two contributions. One is proportional to the form factor for the density of states, with an amplitude determined by the squared average of the matrix elements. The other is constant and related to the fluctuations of finite time classical traje...

We calculate the electromagnetic form factor of the pion in quenched lattice QCD. The non-perturbatively improved Sheikoleslami-Wohlert lattice action is used together with the O(a) improved current. We calculate form factor for pion masses down to mπ = 360 MeV . We compare the mean square radius for the pion extracted from our form factors to the value obtained from the ’Bethe Salpeter amplitu...

B. Aubert, Y. Karyotakis, J. P. Lees, V. Poireau, E. Prencipe, X. Prudent, V. Tisserand, J. Garra Tico, E. Grauges, M. Martinelli, A. Palano, M. Pappagallo, G. Eigen, B. Stugu, L. Sun, M. Battaglia, D.N. Brown, L. T. Kerth, Yu. G. Kolomensky, G. Lynch, I. L. Osipenkov, K. Tackmann, T. Tanabe, C.M. Hawkes, N. Soni, A. T. Watson, H. Koch, T. Schroeder, D. J. Asgeirsson, B.G. Fulsom, C. Hearty, T....