8450139
Electrodynamics modified by some dimension-five Lorentz-violating interactions: radiative corrections
We study radiative corrections to massless quantum electrodynamics modified by two dimension-five LV interactions $$\bar{\Psi } \gamma ^{\mu } b'^{\nu } F_{\mu \nu }\Psi $$Ψ¯γμb′νFμνΨ and $$\bar{\Psi }\gamma ^{\mu }b^{\nu } \tilde{F}_{\mu \nu } \Psi $$Ψ¯γμbνF~μνΨ in the framework of effective field theories. All divergent one-particle-irreducible Feynman diagrams are calculated at one-loop order and several related issues are discussed. It is found that massless quantum electrodynamics modified by the interaction $$\bar{\Psi } \gamma ^{\mu } b'^{\nu } F_{\mu \nu }\Psi $$Ψ¯γμb′νFμνΨ alone is one-loop renormalizable and the result can be understood on the grounds of symmetry. In this context the one-loop Lorentz-violating beta function is derived and the corresponding running coefficients are obtained.
119152066
The Lee–Wick fields out of gravity
Abstract We study the Maxwell–Einstein theory in the framework of effective field theories. We show that the modified one-loop renormalizable Lagrangian due to quantum gravitational effects contains a Lee–Wick vector field as an extra degree of freedom in the theory. Thus gravity provides a natural mechanism for the emergence of this exotic particle.
118566169
Role of t-channel meson exchange in S-wave pi N and K N scattering
The low-energy S-wave pi N and K N scatterings are studied by the K-matrix approach within the meson exchange framework. The t-channel meson exchanges, especially rho and sigma exchanges, are found to play a very important role in these two processes. The t-channel rho exchange determines the isospin structure of the scattering amplitudes, it gives attractive force in the low isospin state but repulsive force in the high isospin state. The t-channel sigma exchange gives a very large contribution in these two processes, while it is negligible in meson-meson S-wave scatterings.