scholarly journals Effective action in a general chiral model: Next to leading order derivative expansion in the worldline method

2008 ◽  
Vol 793 (3) ◽  
pp. 425-450 ◽  
Author(s):  
Andres Hernandez ◽  
Thomas Konstandin ◽  
Michael G. Schmidt
Keyword(s):  
Effective Action ◽  
Order Derivative ◽  
Chiral Model ◽  
Leading Order ◽  
Derivative Expansion

scholarly journals The fermionic universal one-loop effective action

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Sebastian A. R. Ellis ◽  
Jérémie Quevillon ◽  
Pham Ngoc Hoa Vuong ◽  
Tevong You ◽  
Zhengkang Zhang
Keyword(s):  
Path Integral ◽  
Effective Action ◽  
Covariant Derivative ◽  
Heavy Fermion ◽  
Axial Vector ◽  
Derivative Expansion ◽  
Universal Structure ◽  
Pseudo Scalar ◽  
Matching Techniques ◽  
Analytical Expressions

Abstract Recent development of path integral matching techniques based on the covariant derivative expansion has made manifest a universal structure of one-loop effective Lagrangians. The universal terms can be computed once and for all to serve as a reference for one-loop matching calculations and to ease their automation. Here we present the fermionic universal one-loop effective action (UOLEA), resulting from integrating out heavy fermions (Dirac or Majorana) with scalar, pseudo-scalar, vector and axial-vector couplings. We also clarify the relation of the new terms computed here to terms previously computed in the literature and those that remain to complete the UOLEA. Our results can be readily used to efficiently obtain analytical expressions for effective operators arising from heavy fermion loops [13].

scholarly journals RENORMALIZATION GROUP FLOW EQUATIONS FOR THE SCALAR O(N) THEORY

2001 ◽  
Vol 16 (11) ◽  
pp. 2119-2124 ◽  
Author(s):  
B.-J. SCHAEFER ◽  
O. BOHR ◽  
J. WAMBACH
Keyword(s):  
Fixed Point ◽  
Renormalization Group ◽  
Three Dimensions ◽  
Leading Order ◽  
Renormalization Group Flow ◽  
Derivative Expansion ◽  
Scalar Theory ◽  
Flow Equations ◽  
Self Consistent ◽  
Group Flow

Self-consistent new renormalization group flow equations for an O(N)-symmetric scalar theory are approximated in next-to-leading order of the derivative expansion. The Wilson-Fisher fixed point in three dimensions is analyzed in detail and various critical exponents are calculated.

scholarly journals Hermitizing the HAL QCD potential in the derivative expansion

2020 ◽  
Vol 2020 (2) ◽  
Author(s):  
Sinya Aoki ◽  
Takumi Iritani ◽  
Koichi Yazaki
Keyword(s):  
Phase Shift ◽  
Wave Functions ◽  
Leading Order ◽  
Many Body ◽  
Derivative Expansion ◽  
Local Part ◽  
Scattering Phase ◽  
Many Body Systems ◽  
Local Term ◽  
Better Than

Abstract A formalism is given to hermitize the HAL QCD potential, which needs to be non-Hermitian except for the leading-order (LO) local term in the derivative expansion as the Nambu– Bethe– Salpeter (NBS) wave functions for different energies are not orthogonal to each other. It is shown that the non-Hermitian potential can be hermitized order by order to all orders in the derivative expansion. In particular, the next-to-leading order (NLO) potential can be exactly hermitized without approximation. The formalism is then applied to a simple case of $\Xi \Xi (^{1}S_{0}) $ scattering, for which the HAL QCD calculation is available to the NLO. The NLO term gives relatively small corrections to the scattering phase shift and the LO analysis seems justified in this case. We also observe that the local part of the hermitized NLO potential works better than that of the non-Hermitian NLO potential. The Hermitian version of the HAL QCD potential is desirable for comparing it with phenomenological interactions and also for using it as a two-body interaction in many-body systems.

scholarly journals Derivative expansion at small mass for the spinor effective action

2011 ◽  
Vol 83 (10) ◽  
Author(s):  
Gerald V. Dunne ◽  
Adolfo Huet ◽  
Jin Hur ◽  
Hyunsoo Min
Keyword(s):  
Effective Action ◽  
Small Mass ◽  
Derivative Expansion

scholarly journals An All-Orders Derivative Expansion

1997 ◽  
Vol 12 (06) ◽  
pp. 1143-1151 ◽  
Author(s):  
Gerald Dunne
Keyword(s):  
Magnetic Field ◽  
Effective Action ◽  
Exact Result ◽  
Inhomogeneous Magnetic Field ◽  
Derivative Expansion ◽  
Spatially Inhomogeneous ◽  
Convergent Expansion

We evaluate the exact QED2+1 effective action for fermions in the presence of a family of static but spatially inhomogeneous magnetic field profiles. This exact result yields an all-orders derivative expansion of the effective action, and indicates that the derivative expansion is an asymptotic, rather than a convergent, expansion.

One-loop nonlinear correction for QED

2016 ◽  
Vol 31 (27) ◽  
pp. 1650153
Author(s):  
J. S. N. Furtado ◽  
G. R. Silva
Keyword(s):  
Effective Action ◽  
External Momentum ◽  
Nonlinear Correction ◽  
Derivative Expansion

In this work, we study the generation of a nonlinear correction for QED, namely, the Euler–Heisenberg effective action. In order to achieve this, we consider two methods. The first method employed consists in make use of Feynman parametrization to solve the integrals properly, while in the second method a derivative expansion in the external momentum was considered.

scholarly journals The higher derivative expansion of the effective action by the string-inspired method. I

1994 ◽  
Vol 64 (1) ◽  
pp. 111-116 ◽  
Author(s):  
Denny Fliegner ◽  
Michael G. Schmidt ◽  
Christian Schubert
Keyword(s):  
Effective Action ◽  
Derivative Expansion ◽  
Higher Derivative
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