Related papers: Constraints on extra-dimensional theories from vir…
In theories with many copies of the Standard Model virtual black hole exchange may produce effective higher dimensional operators that can be treated below the cutoff scale as fundamental vertices of interspecies non-gravitational…
We perform a global analysis of the bounds from charged lepton flavour violating observables to new physics. We parametrize generic new physics through the Effective Field Theory formalism and perform global fits beyond the common…
This work sets out to compute and discuss effects of spin, velocity and dimensionality on inter-particle potentials systematically derived from gauge field-theoretic models. We investigate the interaction of fermionic particles by the…
We explore the nature of higher dimensional operators generated by quantum gravity. Calculating the tree-level and one-loop effective operators generated by graviton exchange between fields of the standard model and those of a hidden…
We consider the production of gravitons via two photon fusion in Kaluza-Klein theories which allow TeV scale gravitational interactions. We find that the processes l+ l- to l+ l- + graviton, with l=electron or muon can put quite stringent…
We investigate the ability of LEP2 to detect possible $R$-parity violation, especially for the case where direct production cross-sections are too small for all superparticles. We demonstrate that for coupling strengths allowed by present…
Theories of scalars and gravity, with non-minimal interactions, $\sim (M_P^2 +F(\phi) )R +L(\phi)$, have graviton exchange induced contact terms. These terms arise in single particle reducible diagrams with vertices $\propto q^2$ that…
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…
We study the effects of virtual leptoquark exchange on charged current and neutral current processes at HERA, on di-lepton production at the Tevatron, and on quark pair production at LEP II. We present the areas of parameter space that can…
Motivated by recent interest in TeV-scale gravity and especially by the possibility of fast baryon decay mediated by virtual black holes, we study another dangerous aspect of spacetime foam interactions: lepton flavor violation. We…
We discuss the possibility of explaining the excess in the cross section at high-Q^2 recently found at HERA in terms of four-fermion effective interactions. To avoid the constraints from low-energy data, we select three special cases in…
In models with large extra dimensions, where quantum gravity effects become strong at the TeV scale, the rho-parameter can receive large contributions from one-loop diagrams involving exchange of multiple graviton and dilaton states. These…
No theory of four-dimensional quantum gravity exists as yet. In this situation the two-dimensional theory, which can be analyzed by conventional field-theoretical methods, can serve as a toy model for studying some aspects of quantum…
The structure of one, two and three loop counterterms imposes strong constraints on several non--BPS interactions in the low momentum expansion of the three loop four graviton amplitude in maximal supergravity. The constraints are imposed…
We derive constraints on the four dimensional energy-momentum tensor from gravitational and gauge anomalies. Our work can be considered an extension of Duff's analysis [1] to include parity-odd terms and explicit symmetry breaking. The…
Pairs of Standard Model fermions form dimension-3 singlet operators that can couple to new dark sector states. This "fermion portal" is to be contrasted with the lower-dimensional Higgs, vector and neutrino singlet portals. We characterise…
Theories beyond the Standard Model must necessarily respect its gauge symmetry. This implies strict constraints on the possible models of non-standard neutrino interactions, which we analyze. The focus is set on the effective low-energy…
Gravity can become strong at the TeV scale in the theory of extra dimensions. An effective Lagrangian can be used to describe the gravitational interactions below a cut-off scale. In this work, we study the diphoton production in…
We study the constraints on gravity scale $M_P$ in extra-dimension gravitational theory, obtained from gravity-induced processes. The obtained constraints are subdivided into strong (though not robust) and reliable (though less strong). The…
We examine the phenomenological consequences of a supersymmetric bulk in the scenario of large extra dimensions. We assume supersymmetry is realized in the bulk and study the interactions of the resulting bulk gravitino Kaluza-Klein (KK)…