Related papers: Low Energy String: An Aristotelian Top ?
A theory of low temperature (T) electron spin resonance (ESR) in half-integer spin antiferromagnetic chains is developed using field theory methods and avoiding previous approximations. It is compared to experiments on Cu benzoate. Power…
The natural excitations of an interacting one-dimensional system at low energy are hydrodynamic modes of Luttinger liquid, protected by the Lorentz invariance of the linear dispersion. We show that beyond low energies, where quadratic…
We parametrize in a model-independent way possible departures from the minimal Standard Model predictions in the matter sector. We only assume the symmetry breaking pattern of the Standard Model and that new particles are sufficiently heavy…
We show that the electroweak $Z-$string can be stabilized by the presence of bound states of a complex scalar field. We argue that fermions coupled to the scalar field of the string can also make the string stable and discuss the physical…
The Standard Model is the low-energy limit of a microscopic theory which includes extra dimensions and new symmetries. A part of my thesis consisted in constructing a new class of models with two extra dimensions. We showed that these…
Experiment shows that the top quark is far heavier than the other elementary fermions. This finding has stimulated research on theories of electroweak and flavor symmetry breaking that include physics beyond the standard model. Efforts to…
Above the Hagedorn energy density closed fundamental strings form a long string phase. The dynamics of weakly interacting long strings is described by a simple Boltzmann equation which can be solved explicitly for equilibrium distributions.…
We review a class of non-topological defects in the standard electroweak model, and their implications. Starting with the semilocal string, which provides a counterexample to many well known properties of topological vortices, we discuss…
The ten dimensional string theories as well as eleven dimensional supergravity are conjectured to arise as limits of a more basic theory, traditionaly dubbed M--theory. This notion is confined to the ten dimensional supersymmetric theories.…
A fundamental task for the heterotic superstring theory is the determination of the effective action describing the physics of massless string excitations at low energies. This is necessary for the phenomenological applications of string…
These four lectures, addressed to an audience of graduate students in experimental high energy physics, survey some of the basic concepts in string theory. The purpose is to convey a general sense of what string theory is and what it has…
A new dynamical symmetry breaking of $SU(2)_{L}\times U(1)$ caused by the combination of the axial-vector component and the fermion mass is found in electroweak theory. We obtain (m^{2}_{W}={1/2}g^{2}m^{2}_{t}) and (m^{2}_{Z}=\rho…
We construct a simple class of exact solutions of the electroweak theory including the naked $Z$--string and fermion fields. It consists in the $Z$--string configuration ($\phi,Z_\theta$), the {\it time} and $z$ components of the neutral…
Fundamental string theory has been used to show that low energy excitations of certain black holes are described by a two dimensional conformal field theory. This picture has been found to be extremely robust. In this paper it is argued…
The discovery of the Higgs boson at the LHC supports the hypothesis that the Standard Model provides an effective parameterisation of all subatomic experimental data up to the Planck scale. String theory, which provides a viable…
Studying interacting fermions in 1D at high energy, we find a hierarchy in the spectral weights of the excitations theoretically and we observe evidence for second-level excitations experimentally. Diagonalising a model of fermions (without…
We propose a renormalizable theory with minimal particle content and symmetries, that successfully explains the number of Standard Model (SM) fermion families, the SM fermion mass hierarchy, the tiny values for the light active neutrino…
We examine the Standard Model field configurations near cosmic strings in a particular class of models. This class is defined by the condition that the generator of the flux in the string, $T_s$, commutes with the Standard Model Lie…
The top quark is by far the heaviest known fermion [1]. In consequence, experiment is just beginning to explore its properties, and some of them may yet prove to be distinctly non-standard. The very size of the top quark's mass even hints…
Based on a detailed symmetry analysis, we state the general rules to build up the effective low energy field theory describing a system of electrons weakly interacting with the lattice degrees of freedom. The basic elements in our…