The Vector and Scalar Form Factors of the Pion to Two Loops
نویسندگان
چکیده
We calculate the vector and scalar form factors of the pion to two loops in Chiral Perturbation Theory. We estimate the unknown O(p6) constants using resonance exchange. We make a careful comparison to the available data and determine two O(p4) constants rather precisely, and two O(p6) constants less precisely. We also use Chiral Perturbation Theory to two loops to extract in a model–independent manner the charge radius of the pion from the available data, and obtain 〈r〉V = 0.437± 0.016 fm.
منابع مشابه
Covariance Analysis of a vector tracking GPS receiver based on MMSE multiuser Detection
In high dynamic conditions, using vector tracking loops instead of scalar tracking loops in GPS receivers is proved as an efficient method to compensate the performance. The Minimum Mean Squared Error detector as a multiuser detector is applied in the vector tracking loop for more reliability and efficiency. The Kalman filter does the two tasks of tracking and extracting the navigation data aft...
متن کاملVirtual photons in the pion form factors and the energy–momentum tensor
We evaluate the vector and scalar form factor of the pion in the presence of virtual photons at next–to–leading order in two–flavor chiral perturbation theory. We also consider the scalar and tensor pion form factors of the energy–momentum tensor. We find that the intrinsic electromagnetic corrections are very small for the vector and charged pion scalar form factor. The scalar radius of the ne...
متن کاملPion form factors from lattice QCD with exact chiral symmetry
We calculate pion vector and scalar form factors in two-flavor lattice QCD and study the chiral behavior of the vector and scalar radii 〈r〉V,S. For a direct comparison with chiral perturbation theory (ChPT), chiral symmetry is exactly preserved by employing the overlap quark action. We utilize the all-to-all quark propagator in order to calculate the scalar form factor including the contributio...
متن کاملCasimir effects of nano objects in fluctuating scalar and electromagnetic fields: Thermodynamic investigating
Casimir entropy is an important aspect of casimir effect and at the nanoscale is visible. In this paper, we employ the path integral method to obtain a general relation for casimir entropy and internal energy of arbitrary shaped objects in the presence of two, three and four dimension scalar fields and the electromagnetic field. For this purpose, using Lagrangian and based on a perturb...
متن کاملPractical Implementation of Scalar and Vector Control Methods on a Rotor Surface Type Permanent Magnent Synchronous Machine Drive/System Using a PC
In this paper, using a personal computer (PC), the practical implementation of scalar and vector control methods on a three–phase rotor surface- type permanent magnet synchronous machine drive is discussed. Based on the machine dynamic equations and the above control strategies, two block diagrams are presented first for closed-loop speed controlling of the machine drive/system. Then, the desig...
متن کامل