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We derive constraints on the couplings of light vector particles to all first-generation Standard Model fermions using leptonic decays of the charged pion, $\pi^+\to e^+ \nu_e X_\mu$. In models where the net charge to which $X_\mu$ couples…

High Energy Physics - Phenomenology · Physics 2023-09-12 Matheus Hostert , Maxim Pospelov

In the framework of the minimal ${SU}(3)_C\otimes {SU}(3)_L \otimes {U}(1)_N$ model, the lepton-flavour-violating decay $\pi^+ \ra \mu^- \nu_\mu e^+ e^+ $ is calculated without directly invoking lepton mixing. The branching ratio for this…

High Energy Physics - Phenomenology · Physics 2008-11-26 Hoang Ngoc Long

Limits from neutron beta decay on parameters describing physics beyond the Standard Model are presented. New Physics is described by the most general Lorentz invariant effective Hamiltonian involving vector, scalar and tensor operators and…

High Energy Physics - Phenomenology · Physics 2012-01-20 Jacek Holeczek , Michal Ochman , Elzbieta Stephan , Marek Zralek

We investigate lepton-number-violating decays $K^\mp \rightarrow \pi^\pm l^\mp l^\mp$ in the presence of sterile neutrinos. We consider minimal interactions with Standard-Model fields through Yukawa couplings as well as higher-dimensional…

High Energy Physics - Phenomenology · Physics 2022-07-13 Guanghui Zhou

The Auger collaboration has observed the number of muons which is higher than its prediction by existing hadronic interaction models. We explain this excess of muons by using Lorentz invariance violation (LIV) in photon sector. As an…

High Energy Physics - Phenomenology · Physics 2017-06-28 Gaurav Tomar

Precision measurements in allowed nuclear beta decays and neutron decay are reviewed and analyzed both within the Standard Model and looking for new physics. The analysis incorporates the most recent experimental and theoretical…

High Energy Physics - Phenomenology · Physics 2021-07-06 Adam Falkowski , Martín González-Alonso , Oscar Naviliat-Cuncic

A field-theoretical description of the photoproduction of two pions off the nucleon is presented that applies to real as well as virtual photons in the one-photon approximation. The Lorentz-covariant theory is complete at the level of all…

Nuclear Theory · Physics 2015-06-12 Helmut Haberzettl , Kanzo Nakayama , Yongseok Oh

The propagation of photons, electrons and positrons at ultra-high energies above 10^{19} eV can be changed considerably if the dispersion relations of these particles are modified by terms suppressed by powers of the Planck scale. We…

Astrophysics · Physics 2009-09-29 Matteo Galaverni , Guenter Sigl

The role of Lorentz symmetry in noncommutative field theory is considered. Any realistic noncommutative theory is found to be physically equivalent to a subset of a general Lorentz-violating standard-model extension involving ordinary…

High Energy Physics - Theory · Physics 2009-09-25 Sean M. Carroll , Jeffrey A. Harvey , V. Alan Kostelecky , Charles D. Lane , Takemi Okamoto

We investigate a dimension five Lorentz-violating (LV) nonminimal coupling between the neutral vector meson field strength and the pion current in the context of the Kroll-Lee-Zumino (KLZ) model. In this modified model we study the vector…

High Energy Physics - Phenomenology · Physics 2019-09-04 Victor E. Mouchrek-Santos , Manoel M. Ferreira , Carlisson Miller

The constraints on baryogenesis models obtained from an observation of neutrinoless double beta decay are discussed. The lepton number violating processes, which can underlie neutrinoless double beta decay, would together with sphaleron…

High Energy Physics - Phenomenology · Physics 2015-10-23 Lukas Graf , Julia Harz , Wei-Chih Huang

Parity violating asymmetry in inclusive scattering of longitudinally polarized electrons by unpolarized protons with $\pi^0$ or $\pi^+$ meson production, is calculated as a function of the momentum transfer squared $Q^2$ and the total…

Nuclear Theory · Physics 2009-11-06 Michail P. Rekalo , Jacques Arvieux , Egle Tomasi-Gustafsson

I discuss recent developments on non-leptonic and radiative kaon decays mainly related to direct CP-violation within the combined ChPT and 1/N_c expansion approaches. In particular, I review the status of K -> pi pi, epsilon_K', direct…

High Energy Physics - Phenomenology · Physics 2008-11-26 Joaquim Prades

We correct the fitting formula used in refs. [1,2] to obtain a robust limit on a violation of Lorentz invariance that depends linearly on the photon energy. The correction leads to a slight increase of the limit on the scale of the…

Lorentz invariance, the fundamental symmetry of Einstein's theory of Special Relativity, has been established and tested by many classical and modern experiments. However, many theories that unify the Standard Model of particle physics and…

High Energy Astrophysical Phenomena · Physics 2016-08-15 Fabian Kislat , Henric Krawczynski

We discuss the modified Maxwell action of a $K_{F}$-type Lorentz symmetry breaking theory and present a solution of Maxwell equations derived in the cases of linear and elliptically polarized electromagnetic waves in the vacuum of CPT-even…

General Physics · Physics 2017-05-30 Thiago Prudencio , Humberto Belich

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

In this paper, we derive the non-commutative corrections to the maximal acceleration of a massive particle. Using the eight-dimensional kappa-deformed phase-space metric, we obtain the kappa-deformed maximal acceleration, valid up to first…

High Energy Physics - Theory · Physics 2020-12-23 E. Harikumar , Vishnu Rajagopal

We propose a new Lorentz invariant violating extension for the pure photonic sector of the Standard Model due to the condensation of topological defects in the context of the Julia-Toulouse mechanism. Possible physical consequences leading…

High Energy Physics - Phenomenology · Physics 2008-11-26 Patricio Gaete , Clovis Wotzasek

In this work analyze the physical consistency of a nonbirefringent Lorentz-violating planar model via the analysis of the pole structure of its Feynman propagators. The nonbirefringent planar model, obtained from the dimensional reduction…

High Energy Physics - Theory · Physics 2012-08-14 Rodolfo Casana , Manoel M. Ferreira , Roemir P. M. Moreira