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A. Krzywicki

Publications and source records attributed to A. Krzywicki.

33 records · Page 2Linked to original sources
arXiv1999

Wilson Fermions on a Randomly Triangulated Manifold

A general method of constructing the Dirac operator for a randomly triangulated manifold is proposed. The fermion field and the spin connection live, respectively, on the nodes and on the links of the corresponding dual graph. The construction is carried out explicitly in 2-d, on an arbitrary orientable manifold without boundary. It can be easily converted into a computer code. The equivalence, on a sphere, of Majorana fermions and Ising spins in 2-d is rederived. The method can, in principle, be extended to higher dimensions.

hep-lat↗
arXiv1999

The Likelihood of DCC Formation

We estimate the probability that a disoriented chiral condensate forms during the spherical expansion of a hot medium described by the linear sigma model.

hep-ph↗
arXiv1998

The Strong-Coupling Expansion in Simplicial Quantum Gravity

We construct the strong-coupling series in 4d simplicial quantum gravity up to volume 38. It is used to calculate estimates for the string susceptibility exponent gamma for various modifications of the theory. It provides a very efficient way to get a first view of the phase structure of the models.

hep-lat↗
arXiv1998

4d Simplicial Quantum Gravity: Matter Fields and the Corresponding Effective Action

Four-dimensional simplicial quantum gravity is modified either by coupling it to U(1) gauge fields or by introducing a measure weighted by the orders of the triangles. Strong coupling expansion and Monte Carlo simulations are used. Although the two modifications of the standard pure-gravity model are apparently very distinct, they produce strikingly similar results, as far as the geometry of random manifolds is concerned. In particular, for an appropriate choice of couplings, the branched polymer phase is replaced by a crinkled phase, characterized by the susceptibility exponent $γ< 0$ and the fractal dimension $d_H > 2$. The quasi-equivalence between the two models is exploited to get further insight into the extended phase diagram of the theory.

hep-lat↗
arXiv1997

4d Simplicial Quantum Gravity Interacting with Gauge Matter Fields

The effect of coupling non-compact $U(1)$ gauge fields to four dimensional simplicial quantum gravity is studied using strong coupling expansions and Monte Carlo simulations. For one gauge field the back-reaction of the matter on the geometry is weak. This changes, however, as more matter fields are introduced. For more than two gauge fields the degeneracy of random manifolds into branched polymers does not occur, and the branched polymer phase seems to be replaced by a new phase with a negative string susceptibility exponent $γ$ and fractal dimension $d_H \approx 4$.

hep-lat↗
arXiv1997

Focusing on the Fixed Point of 4D Simplicial Gravity

Our earlier renormalization group analysis of simplicial gravity is extended. A high statistics study of the volume and coupling constant dependence of the cumulants of the node distribution is carried out. It appears that the phase transition of the theory is of first order, contrary to what is generally believed.

hep-lat↗
arXiv1996

Branched Polymers with Loops

We propose a classification of critical behaviours of branched polymers for arbitrary topology. We show that in an appropriately defined double scaling limit the singular part of the partition function is universal. We calculate this partition function exactly in the generic case and perturbatively otherwise. In the discussion section we comment on the relation between branched polymer theory and Euclidean quantum gravity.

hep-th↗
arXiv1996

Phase transition and topology in 4d simplicial gravity

We present data indicating that the recent evidence for the phase transition being of first order does not result from a breakdown of the ergodicity of the algorithm. We also present data showing that the thermodynamical limit of the model is independent of topology.

hep-lat↗
arXiv1995

Perspectives in Lattice Gravity

We briefly overview the development of Euclidean quantum gravity in four dimensions regarded as a branch of statistical mechanics of discretized random manifolds.

hep-lat↗
arXiv1995

Towards a Non-Perturbative Renormalization of Euclidean Quantum Gravity

A real space renormalization group technique, based on the hierarchical baby-universe structure of a typical dynamically triangulated manifold, is used to study scaling properties of 2d and 4d lattice quantum gravity. In 4d, the $β$-function is defined and calculated numerically. An evidence for the existence of an ultraviolet stable fixed point of the theory is presented

hep-th↗
arXiv1994

Random Geometries and Real Space Renormalization Group

A method of ``blocking'' triangulations that rests on the self-similarity feature of dynamically triangulated random manifolds is proposed. The method is used to define the renormalization group for random geometries. As an illustration, the idea is applied to pure euclidean quantum gravity in two dimensions. Generalisation to more complicated systems and to higher dimensionalities of space-time appears straightforward.

hep-lat↗
arXiv1994

Dynamics of a Disoriented Chiral Condensate

We use the linear $σ$ model to analyse the dynamics of a disoriented chiral condensate. For idealized boundary conditions appropriate to high energy collisions, the problem can be reduced to a one dimensional one. The evolution of the chiral state is then that of a simple dynamical system and can be studied analytically.

hep-ph↗
arXiv1994

Grand-Canonical Ensemble of Random Surfaces with Four Species of Ising Spins

The grand-canonical ensemble of dynamically triangulated surfaces coupled to four species of Ising spins (c=2) is simulated on a computer. The effective string susceptibility exponent for lattices with up to 1000 vertices is found to be $γ= - 0.195(58)$. A specific scenario for $c > 1$ models is conjectured.

hep-th↗