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Full-Text Articles in Physics
Contributions To Pion Decay From Lorentz Violation In The Weak Sector, Brett David Altschul
Contributions To Pion Decay From Lorentz Violation In The Weak Sector, Brett David Altschul
Faculty Publications
Lorentz violation in the weak sector would affect the β-decay lifetimes of pions. The decay amplitude may be rendered anisotropic, but only an isotropic violation of boost invariance can affect the net lifetime in the center-of-mass frame. However, since the rest frames of the pions that produce the NuMI neutrino beam at Fermilab vary with the rotation of the Earth, it is possible to constrain anisotropic Lorentz violation using prior analyses of sidereal variations in the event rate at the MINOS near detector. The resulting bounds on weak-sector Lorentz violation are at the 10−4 level, a substantial improvement over …
Neutrino Beam Constraints On Flavor-Diagonal Lorentz Violation, Brett David Altschul
Neutrino Beam Constraints On Flavor-Diagonal Lorentz Violation, Brett David Altschul
Faculty Publications
Breaking of isotropy and Lorentz boost invariance in the dynamics of second-generation leptons would lead to direction-dependent changes in the lifetimes of charged pions. This would make the intensity of a neutrino beam produced via pion decay a function of the beam orientation. The experimental signature of this phenomenon—sidereal variations in the event rate at a downstream neutrino detector—has already been studied, in searches for Lorentz-violating neutrino oscillations. Existing analyses of MINOS near detector data can be used to constrain the flavor-diagonal Lorentz violation coefficients affecting muon neutrino speeds at roughly the 10−5 level.
Coupling Right- And Left-Handed Photons Differently To Charged Matter, Brett David Altschul
Coupling Right- And Left-Handed Photons Differently To Charged Matter, Brett David Altschul
Faculty Publications
We consider a modification of electrodynamics in which right- and left-circularly polarized photons are coupled to charged sources differently. Even though photon helicity is a Lorentz invariant quantity, such a modification breaks Lorentz symmetry, as well as locality. The modified theory includes novel magnetic forces between perpendicular currents. Existing data can be used to constrain the modification at approximately a 2 x 10^(-3) level.
Lorentz Violation And The Higgs Mechanism, Brett David Altschul
Lorentz Violation And The Higgs Mechanism, Brett David Altschul
Faculty Publications
We consider scalar quantum electrodynamics in the Higgs phase and in the presence of Lorentz violation. Spontaneous breaking of the gauge symmetry gives rise to Lorentz-violating gauge field mass terms. These may cause the longitudinal mode of the gauge field to propagate superluminally. The theory may be quantized by the Faddeev-Popov procedure, although the Lagrangian for the ghost fields also needs to be Lorentz violating.
Consequences Of Neutrino Lorentz Violation For Leptonic Meson Decays, Brett David Altschul
Consequences Of Neutrino Lorentz Violation For Leptonic Meson Decays, Brett David Altschul
Faculty Publications
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 another observable, the charged pion decay rate. The rate decreases by an factor [1 - 3/(1 - (m_mu)^2 / (m_pi) ^ 2) (< v_(nu) > - 1)], where < v_(nu) > is the (directionally averaged) neutrino speed in the pion's rest frame. This provides a completely independent experimental observable that is sensitive to the same forms of Lorentz violation as a neutrino time of flight measurement.
Bounding Lorentz Violation At Particle Colliders By Tracking The Motion Of Charged Particles, Brett David Altschul
Bounding Lorentz Violation At Particle Colliders By Tracking The Motion Of Charged Particles, Brett David Altschul
Faculty Publications
In the presence of Lorentz violation, the motion of a charged particle in a magnetic field is distorted. By measuring the eccentricities of particles’ elliptical orbits and studying how those eccentricities vary with the absolute orientation of the laboratory, it is possible to constrain the Lorentz-violating cJK parameters. For each observed species, this method can provide constraints on four linear combinations of coefficients for which, in some species, there are presently no two-sided bounds.
Lorentz Violation With An Antisymmetric Tensor, Brett David Altschul, Quentin G. Bailey, Alan Kostelecky
Lorentz Violation With An Antisymmetric Tensor, Brett David Altschul, Quentin G. Bailey, Alan Kostelecky
Faculty Publications
Field theories with spontaneous Lorentz violation involving an antisymmetric 2-tensor are studied. A general action including nonminimal gravitational couplings is constructed, and features of the Nambu-Goldstone and massive modes are discussed. Minimal models in Minkowski spacetime exhibit dualities with Lorentz-violating vector and scalar theories. The post-Newtonian expansion for nonminimal models in Riemann spacetime involves qualitatively new features, including the absence of an isotropic limit. Certain interactions producing stable Lorentz-violating theories in Minkowski spacetime solve the renormalization-group equations in the tadpole approximation.
Bounding Isotropic Lorentz Violation Using Synchrotron Losses At Lep, Brett David Altschul
Bounding Isotropic Lorentz Violation Using Synchrotron Losses At Lep, Brett David Altschul
Faculty Publications
Some deviations from special relativity—especially isotropic effects—are most efficiently constrained using particles with velocities very close to 1. While there are extremely tight bounds on some of the relevant parameters coming from astrophysical observations, many of these rely on our having an accurate understanding of the dynamics of these high-energy sources. It is desirable to have reliable laboratory constraints on these same parameters. The fastest-moving particles in a laboratory were electrons and positrons at LEP. The energetics of the LEP beams were extremely well understood, and measurements of the synchrotron emission rate indicate that the isotropic Lorentz violation coefficient |˜κ …