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Chiral symmetry serves as a guiding principle in low-energy hadron dynamics. An effective lagrangian, which explicitly breaks chiral symmetry via a small mass term, allows for a systematic method of calculating higher order corrections to…

Nuclear Theory · Physics 2007-05-23 F. Myhrer

The behavior of fermions in the presence of Lorentz and CPT violation is studied. Allowing for operators of any mass dimension, we classify all Lorentz-violating terms in the quadratic Lagrange density for free fermions. The result is…

High Energy Physics - Phenomenology · Physics 2015-06-03 Alan Kostelecky , Matthew Mewes

Two-point functions related to the pion weak decay constant $f_\pi$ are calculated from the generating functional of chiral perturbation theory in the mean field approximation and the heavy-baryon limit. The aim is to demonstrate that…

High Energy Physics - Phenomenology · Physics 2016-09-06 M. Kirchbach , A. Wirzba

We provide an introduction to the power-counting issue in baryon chiral perturbation theory and discuss some recent developments in the manifestly Lorentz-invariant formulation of the one-nucleon sector. As explicit applications we consider…

High Energy Physics - Phenomenology · Physics 2014-11-20 Stefan Scherer

The issue of Lorentz fine-tuning in effective theories containing higher-order operators is studied. To this end, we focus on the Myers-Pospelov extension of QED with dimension-five operators in the photon sector and standard fermions. We…

High Energy Physics - Phenomenology · Physics 2015-05-18 Carlos M. Reyes , Sebastian Ossandon , Camilo Reyes

The effects of perturbative Lorentz and CPT violation on neutrino oscillations are studied. Features include neutrino-antineutrino oscillations, direction dependence, and unconventional energy behavior. Leading-order corrections arising…

High Energy Physics - Phenomenology · Physics 2009-10-20 Jorge S. Diaz , Alan Kostelecky , Matthew Mewes

We place several new limits on Lorentz violating effects, which can modify particles' dispersion relations, by considering the highest energy cosmic rays observed. Since these are hadrons, this involves considering the partonic content of…

High Energy Physics - Phenomenology · Physics 2009-11-10 Olivier Gagnon , Guy D. Moore

The hadronic sector of the standard model at low energies is described by a non--decoupling effective field theory, chiral perturbation theory. An introduction is given to the construction of effective chiral Lagrangians, both in the purely…

High Energy Physics - Phenomenology · Physics 2011-04-15 G. Ecker

Parity violating (PV) contributions due to interference between $\gamma$ and $Z^0$ exchange are calculated for pion electroproduction off the nucleon. A phenomenological model with effective Lagrangians is used to determine the resulting…

Nuclear Theory · Physics 2015-06-26 H. -W. Hammer , D. Drechsel

Neutrino oscillations provide an opportunity for sensitive tests of Lorentz invariance. This talk reviews some aspects of Lorentz violation in neutrinos and the prospect of testing Lorentz invariance in neutrino-oscillation experiments. A…

High Energy Physics - Phenomenology · Physics 2016-11-03 Matthew Mewes

In pure chiral perturbation theory (ChPT) the couplings of higher order Lagrangian terms are running parameters and hence can be determined only empirically from various low-energy hadronic processes. While this scenario works well for…

High Energy Physics - Phenomenology · Physics 2007-05-23 Hai-Yang Cheng

The effects of Lorentz Invariance Violation(LIV) operators up to dimension 6 in long baseline neutrino experiments are discussed, in specific for DUNE and T2K. A phenomenological Lagrangian is proposed followed by a computation of the…

High Energy Physics - Phenomenology · Physics 2018-07-04 H. Jurkovich , Pedro Pasquini , C. P. Ferreira

If the observation by OPERA of apparently superluminal neutrinos is correct, the Lagrangian for second-generation leptons must break Lorentz invariance. We calculate the effects of an energy-independent change in the neutrino speed on…

High Energy Physics - Phenomenology · Physics 2011-11-15 Brett Altschul

Exceptional sensitivity to spacetime torsion can be achieved by searching for its couplings to fermions. Recent experimental searches for Lorentz violation are exploited to extract new constraints involving 19 of the 24 independent torsion…

General Relativity and Quantum Cosmology · Physics 2009-11-13 Alan Kostelecky , Neil Russell , Jay Tasson

The effects of the CP violating $\theta$ term in the QCD Lagrangian upon low energy hadronic phenomenology are reconsidered. Strong CP violating interactions among Goldstone bosons and octet baryons are incorporated into an effective chiral…

High Energy Physics - Phenomenology · Physics 2010-11-01 Peter Cho

This brief review discusses Lorentz-violating operators of arbitrary dimension within the photon and neutrino sectors of the Standard-Model Extension.

High Energy Physics - Phenomenology · Physics 2017-08-23 Matthew Mewes

A scheme to derive hadronic interactions induced by effective multi-quark terms is presented within the framework of chiral effective field theory. It is employed to work out the list of parity- and time-reversal-symmetry-violating hadronic…

High Energy Physics - Phenomenology · Physics 2015-05-19 J. Bsaisou , Ulf-G. Meißner , A. Nogga , A. Wirzba

Charm and bottom mesons and baryons are incorporated into a low energy chiral Lagrangian. Interactions of the heavy hadrons with light octet Goldstone bosons are studied in a framework which represents a synthesis of chiral perturbation…

High Energy Physics - Phenomenology · Physics 2010-11-01 Peter Cho

In this thesis we explore a diverse array of issues that strike at the inherently nonperturbative structure of hadrons at momenta below the QCD confinement scale. In so doing, we mainly seek a better control over the partonic substructure…

High Energy Physics - Phenomenology · Physics 2014-08-26 T. J. Hobbs

We construct the most general low-energy effective lagrangian including local parity violating terms parametrized by an axial chemical potential or chiral imbalance $\mu_5$, up to ${\cal O}(p^4)$ order in the chiral expansion for two light…

High Energy Physics - Phenomenology · Physics 2020-07-15 Domènec Espriu , Angel Gómez Nicola , Andrea Vioque-Rodríguez