De sitter space and perpetuum mobile

The general arguments that any interacting nonconformal classical field theory in de Sitter space leads to the possibility of constructing a perpetuum mobile is given. The arguments are based on the observation that massive free falling particles can radiate other massive particles on the classical level as seen by the free falling observer. The intensity of the radiation process is not zero even for particles with any finite mass, i.e., with a wavelength which is within causal domain. Hence, we conclude that either de Sitter space cannot exist eternally or that one can build a perpetuum mobile.     

The electroweak axion,dark energy,inflation and baryonic matter

Journal of Experimental and Theoretical Physics - In a previous paper [1], the standard model was generalized to include an electroweak axion which carries baryon plus lepton number, B + L. It was...     

The superlight axion and neutrino masses

Zeitschrift für Physik C Particles and Fields - It is argued that the Peccei—QuinnU(1) PQ symmetry, needed to solve the strong CP-problem, and the localB−L symmetry of weak...     

The horizontal axion alternative: The interplay of vacuum structure and flavor interactions

We classify all minimal N-generational SU(3) × SU(2) × U(1) axion models according to the structure of their vacuum manifold M, showing that n ≡ π₀(M) is such that 1 ? n ? N. For n < N, the purely axial U(1)_A must be explicitly broken in the Yukawa sector, implying that U(1)_PQ necessarily distinguishes some quark families. In fact, a complete distinction, i.e. a fully horizontal realization of U(1)_PQ does exist for arbitrary N, leading to definite flavor interaction patterns with non-trivial relative structure of the mass matrices M_u versus M_d. For each n, in particular for the domain-wall-free n = 1 case, we find a unique Yukawa pattern embeddable in unified SU(5), whereas SO(10) can only host n = N. It is emphasized that axion invisibility guarantees the invisibility of flavor changing neutral currents.     

Strong CP problem and mirror world: the Weinberg–Wilczek axion revisited

A new possibility for solving the strong CP problem is suggested. It is based on the concept of a mirror world of particles, with the gauge symmetry and Lagrangian completely identical to that of the observable particles. We assume that the ordinary and mirror sectors share the same Peccei–Quinn symmetry realized à la Weinberg–Wilczek, so that the θ-terms are simultaneously canceled by the axion VEV in both worlds. This property remains valid even if the symmetry between two sectors is spontaneously broken and the weak scale of the mirror world is larger than the ordinary weak scale, in which case also the mirror QCD scale becomes larger than the ordinary one. In this situation our axion essentially represents a Weinberg–Wilczek axion of the mirror world with quite a large mass, while it couples the ordinary particles like an invisible axion. The experimental and astrophysical limits are discussed and an allowed parameter window is found with the Peccei–Quinn scale f_a10⁴–10⁵ GeV and the axion mass m_a1 MeV, which can be accessible for future experiments. We also show that our solution to the strong CP problem is stable against the Planck scale induced effects.     

Type IIB orientifolds,D‐brane instantons and the LARGE volume scenario

This review article is concerned with three topics important for the construction of four‐dimensional models of particle physics in the context of type II String Theories. Special emphasis is put on a consistent presentation of these topics as well as on highlighting their interconnections. The first of the three topics deals with the tadpole cancellation conditions and the cancellation of chiral anomalies for type IIB orientifolds with orientifold three‐ and seven‐planes. The second topic is related to non‐perturbative effects originating from D‐brane instantons. In particular, in the presence of a realistic particle physics sector, a chiral zero‐mode constraint for contribution of instantons to the superpotential arises. The third topic is about moduli stabilisation in type IIB string compactifications. Two scenarios, the KKLT and Large Volume Scenario, are reviewed and a model for the latter scenario with the chiral zero‐mode constraint taken into account is presented.     

Primakoff effect: Synchrotron and coulomb mechanisms of axion emission

The Primakoff effect-induced radiative emission of axions by an alternating electromagnetic field, F _a → γa, is considered for the first time. The synchrotron mechanism and the Coulomb mechanism—in the latter case, the alternating field is formed when a charge executes an infinite motion in the field of a Coulomb center—are considered as specific examples. The contributions of these effects to the axion emissivity of magnetic neutron stars and of the Sun are estimated.     

Self-Similarity Breaking: Anomalous Nonequilibrium Finite-Size Scaling and Finite-Time Scaling

Symmetry breaking plays a pivotal role in modern physics.Although self-similarity is also a symmetry,and appears ubiquitously in nature,a fundamental question arises as to whether self-similarity breaking makes sense or not.Here,by identifying an important type of critical fluctuation,dubbed‘phases fluctuations’,and comparing the numerical results for those with self-similarity and those lacking self-similarity with respect to phases fluctuations,we show that self-similarity can indeed be broken,with significant consequences,at least in nonequilibrium situations.We find that the breaking of self-similarity results in new critical exponents,giving rise to a violation of the well-known finite-size scaling,or the less well-known finite-time scaling,and different leading exponents in either the ordered or the disordered phases of the paradigmatic Ising model on two-or three-dimensional finite lattices,when subject to the simplest nonequilibrium driving of linear heating or cooling through its critical point.This is in stark contrast to identical exponents and different amplitudes in usual critical phenomena.Our results demonstrate how surprising driven nonequilibrium critical phenomena can be.The application of this theory to other classical and quantum phase transitions is also anticipated.     

Two-Dimensional Critical Percolation: The Full Scaling Limit

We use SLE ₆ paths to construct a process of continuum nonsimple loops in the plane and prove that this process coincides with the full continuum scaling limit of 2D critical site percolation on the triangular lattice – that is, the scaling limit of the set of all interfaces between different clusters. Some properties of the loop process, including conformal invariance, are also proved.Research partially supported by a Marie Curie Intra-European Fellowship under contract MEIF-CT-2003-500740 and by a Veni grant of the Dutch Organization for Scientific Research (NWO).Research partially supported by the U.S. NSF under grant DMS-01-04278.