Related papers: Expectation Values, Lorentz Invariance, and CPT in…
We propose that local Lorentz invariance is spontaneously violated at high energies, due to a nonvanishing vacuum expectation value of a vector field \phi^\mu, as a possible explanation of the observation of ultra-high energy cosmic rays…
Over the past several decades, dozens of tests have sought Lorentz violation in the nonrelativistic limit of the minimal matter sector of the Standard-Model Extension. Of the 132 Lorentz-violating degrees of freedom that are observable in…
Two-point tree-level amplitudes in bosonic closed string theory are described by a correlation function within the BRST formalism, which respects manifest Lorentz and conformal invariance. In the derivation of the two-point amplitudes, we…
We present how to further the search for Lorentz and CPT violation in the top-quark sector after the first measurement in this sector by D0. We compute the Lorentz-violating matrix element for top pair production via gluon fusion, which…
We supplement the string field theory action with boundary terms to make its variational principle well-posed. Central to our considerations is the violation of the stress-energy tensor conservation in non-compact CFTs due to the boundary…
If Lorentz symmetry is broken, it must have occurred dynamically, via a vector or tensor field whose potential energy forces it to take on a non-zero background expectation value "in vacuum". If the set of minima of this potential (the…
The CPT theorem has been tested to very high precision in a variety of experiments involving particles and antiparticles confined within Penning traps. These tests include comparisons of anomalous magnetic moments and charge-to-mass ratios…
Investigation of conservation/violation of CP symmetry in the leptonic sector is very essential in understanding the evolution of the universe. Lorentz invariance and CPT are fundamental symmetries of nature. The violation of Lorentz…
Spontaneous breaking of CPT is possible in string theory. We show that it can arise at a level within reach of experiments at meson factories currently being built or designed. For $\phi$, $B$, and $\tau$-charm factories, we discuss the…
A popular framework for exploring Lorentz violation is the Standard Model Extension. This extension contains a large number of parameters that can be bounded in various experiments. Most studies, however, focus on the fermion or photon…
A new family of non critical bosonic string backgrounds in arbitrary space time dimension $D$ and with $ISO(1,D-2)$ Poincar\'e invariance are presented. The metric warping factor and dilaton agree asymptotically with the linear dilaton…
We develop a perturbative framework with which to discuss departures from exact Lorentz invariance and explore their potentially observable ramifications. Tiny non-invariant terms introduced into the standard model Lagrangian are assumed to…
A number of different approaches to quantum gravity are at least partly phenomenologically characterized by their treatment of Lorentz symmetry, in particular whether the symmetry is exact or modified/broken at the smallest scales. For…
In Witten's open cubic bosonic string field theory and Berkovits' superstring field theory we investigate solutions of the equations of motion with appropriate source terms, which correspond to Callan-Maldacena solution in Born-Infeld…
Colladay and Kostelecky have proposed a framework for studying Lorentz and CPT violation in a natural extension of the Standard Model. Although numerous bounds exist on the Lorentz and CPT violating parameters in the gauge boson and fermion…
Lorentz invariance violation is a feature of several quantum gravity models in which Lorentz symmetry is broken at high energies, possibly leading to changes in particle behavior and interactions. In this work, we investigate vacuum…
We study a recently proposed generalization of the relativistic particle by Kosteleck\'y, that includes explicit Lorentz violation. We present an alternative action for this system and we show that this action can be interpreted as a…
Open string field theory in the level truncation approximation is considered. It is shown that the energy conservation law determines existence of rolling tachyon solution. The coupling of the open string field theory action to a…
We consider the static potential in theories exhibiting spontaneous symmetry breaking. We use our findings to calculate the static potential of the Standard Model at one-loop order. We do so in both the Wilson loop and scattering amplitude…
Tiny violations of the Lorentz symmetry of relativity and the associated discrete CPT symmetry could emerge in a consistent theory of quantum gravity such as string theory. Recent evidence for linear polarization in gamma-ray bursts…