Related papers: Torsion in Extra Dimensions and One-Loop Observabl…
We attempt to build systematically the low-energy effective Lagrangian for the Einstein--Cartan formulation of gravity theory that generally includes the torsion field. We list all invariant action terms in certain given order; some of the…
Top interactions beyond the Standard Model can be conveniently described in the framework of gauge-invariant effective operators. We briefly review the general form of the fermion-fermion-gauge boson and fermion-fermion-Higgs interactions…
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…
Arkani-Hamed, Dimopoulos, and Dvali have proposed that the fundamental gravitational scale is close to 1 TeV, and that the observed weakness of gravity at long distances is explained by the presence of large extra compact dimensions. If…
Asymmetry measurements in $e^+e^-\to\tau^+\tau^-$ constitute a promising avenue to obtain competitive constraints on the $\tau$ dipole moments, the anomalous magnetic moment $a_\tau$ and the electric dipole moment $d_\tau$, especially, once…
The four-fermion gravitational interaction is induced by torsion, and gets essential on the Planck scale. On this scale, the axial-axial contribution dominates strongly in the discussed interaction. The energy-momentum tensor, generated by…
Limits on gravitational Cherenkov radiation by cosmic rays are obtained and used to constrain coefficients for Lorentz violation in the gravity sector associated with operators of even mass dimensions, including orientation-dependent…
We consider a model with extra compact dimensions in which only gravity exists in the 4+n dimensional bulk. If the gravitational connection is not assumed to be symmetric, that is, unless torsion is artificially set to zero, then a…
Astrophysical bounds severely limit the possibility of observing collider signals of gravity with less than 3 flat extra dimensions. However, small distortions of the compactified space can lift the masses of the lightest graviton…
We present collider tests of the recent proposal for weak-scale quantum gravity due to new large compact space dimensions in which only the graviton ($\G$) propagates. We show that the existing high precision LEP-I $Z$-pole data can impose…
A calculational scheme of quantum-gravitational effects on the physical quantities is proposed. The calculations are performed in 4-$\epsilon$ dimension with $1/N$-expansion scheme, where the Einstein gravity is renormalizable and it has an…
Physics from beyond the Standard Model can induce four fermion operators involving a quark, an anti-quark, a lepton and an anti-lepton. The coefficients of these operators can be constrained by various observations. We update the bounds…
In theories with large extra dimensions, constraints from cosmology lead to non-trivial lower bounds on the fundamental scale M_F, corresponding to upper bounds on the radii of the compact extra dimensions. These constraints are especially…
It has been proposed recently that the scale of strong gravity can be very close to the weak scale. Dimensions of sizes anywhere from $\sim $mm to $\sim $TeV$^{-1}$ can be populated by bulk gravitons, vector bosons and fermions. In this…
Four-fermion operators may have large anomalous scaling and become relevant operators in some strongly interacting gauge theories. We present a detailed model which illustrates some of the implications of such operators for the generation…
In the context of brane-world scenarios, we study the effects produced by the exchange of virtual massive branons. A one-loop calculation is performed which generates higher-dimensional operators involving SM fields suppressed by powers of…
Supergravity theory in $2+\epsilon$ dimensions is studied. It is invariant under supertransformations in 2 and 3 dimensions. One-loop divergence is explicitly computed in the background field method and a nontrivial fixed point is found. In…
Fermion compositeness, and other types of new physics that can be described by the exchange of very massive particles, can manifest themselves as the result of an effective four-fermion contact interaction. In the case of the processes…
We explore spacetime torsion in a two-dimensional setting, wherein it corresponds to a vector field. Without invoking field equations of a particular gravitational theory, we develop visualization techniques for such torsion fields,…
Fermion compositness, and other new physics which can be described by an exchange of very massive particles ($Z^\prime$ boson, leptoquarks, sparticles with R-parity violating couplings), can be manifest itself as the presence of a strong…