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Register a new userGeneral CPT-even dimension-five nonminimal couplings between fermions and photons yielding EDM and MDM
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In this letter, we examine a new class of CPT-even nonminimal interactions, between fermions and photons, deprived of higher order derivatives, that yields electric dipole moment (EDM) and magnetic dipole moment (MDM) in the context of the Dirac equation. The couplings are dimension-five CPT-even and Lorentz-violating nonminimal structures, composed of a rank-2 tensor, $T_{mu u}$, the electromagnetic tensor, and gamma matrices, being addressed in its axial and non-axial Hermiti
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We examine a new class of CPT-even and dimension-five nonminimal interactions between fermions and photons, deprived of higher-order derivatives, yielding electric dipole moment and magnetic dipole moment in the context of the Dirac equation. These couplings are Lorentz-violating nonminimal structures, composed of a rank-2 tensor, the electromagnetic tensor, and gamma matrices, being addressed in its axial and non-axial hermiti
The electric dipole moment (EDM) of an atom could arise also from $P$-odd and $T$-odd electron-nucleon couplings. In this work we investigate a general class of dimension-$6$ electron-nucleon ($e$-$N$) nonminimal interactions mediated by Lorentz-violating (LV) tensors of rank ranging from $1$ to $4$. The possible couplings are listed as well as their behavior under $C$, $P$ and $T$, allowing us to select the couplings compatible with EDM physics. The unsuppressed contributions of these couplings to the atoms Hamiltonian can be read as EDM-equivalent. The LV coefficients magnitudes are limited using EDM experimental data to the level of $3.2times 10^{-13} text{(GeV)}^{-2}$ or $1.6times10^{-15} text{(GeV)}^{-2}$.
Electric dipole moments of atoms can arise from P-odd and T-odd electron--nucleon couplings. This work studies a general class of dimension-six electron--nucleon interactions mediated by Lorentz-violating tensors of ranks ranging from $1$ to $4$. The possible couplings are listed as well as their behavior under C, P, and T, allowing us to select the couplings compatible with electric-dipole-moment physics. The unsuppressed contributions of these couplings to the atoms hamiltonian can be read as equivalent to an electric dipole moment. The Lorentz-violating coefficients magnitudes are limited using electric-dipole-moment measurements at the levels of $3.2times10^{-31}text{(eV)}^{-2}$ or $1.6times10^{-33}text{(eV)}^{-2}$.
We perform a general analysis of the R-parity conserving dimension-five operators that can be present beyond the Minimal Supersymmetric Standard Model. Not all these operators are actually independent. We present a method which employs spurion-dependent field redefinitions that removes this redundancy and establishes the minimal, irreducible set of these dimension-five operators. Their potential effects on the MSSM Higgs sector are discussed to show that the tree level bound $m_hleq m_Z$ cannot be easily lifted within the approximations used, and quantum corrections are still needed to satisfy the LEPII bound. An ansatz is provided for the structure of the remaining couplings in the irreducible set of D=5 operators, which avoids phenomenological constraints from flavor changing neutral currents. The minimal set of operators brings new couplings in the effective Lagrangian, notably wrong-Higgs Yukawa couplings and contact fermion-fermion-scalar-scalar interactions, whose effects are expected to be larger than those generated in the MSSM at loop or even tree level. This has implications in particular for LHC searches for supersymmetry by direct squark production.
In this paper, we consider an electrodynamics of higher derivatives coupled to a Lorentz-violating background tensor. Specifically, we are interested in a dimension-five term of the CPT-odd sector of the nonminimal Standard-Model Extension. By a particular choice of the operator $hat{k}_{AF}$, we obtain a higher-derivative version of the Carroll-Field-Jackiw (CFJ) term, $frac{1}{2}epsilon^{kappalambdamu u}A_{lambda}D_{kappa}square F_{mu u}$, with a Lorentz-violating background vector $D_{kappa}$. This modification is subject to being investigated. We calculate the propagator of the theory and from its poles, we analyze the dispersion relations of the isotropic and anisotropic sectors. We verify that classical causality is valid for all parameter choices, but that unitarity of the theory is generally not assured. The latter is found to break down for certain configurations of the background field and momentum. In an analog way, we also study a dimension-five anisotropic higher-derivative CFJ term, which is written as $epsilon^{kappalambdamu u}A_{lambda}T_{kappa}(Tcdotpartial)^{2}F_{mu u}$ and is directly linked to the photon sector of Myers-Pospelov theory. Within the second model, purely timelike and spacelike $T_{kappa}$ are considered. For the timelike choice, one mode is causal, whereas the other is noncausal. Unitarity is conserved, in general, as long as the energy stays real - even for the noncausal mode. For the spacelike scenario, causality is violated when the propagation direction lies within certain regimes. However, there are particular configurations preserving unitarity and strong numerical indications exist that unitarity is guaranteed for all purely spacelike configurations. The results improve our understanding of nonminimal CPT-odd extensions of the electromagnetic sector.
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