Noncommutative differential calculus and lattice gauge theory

From continuum to lattice theory via deformation of the differential calculus

A differential calculus on an associative algebra A is an algebraic analogue of the calculus of differential forms on a smooth manifold. It supplies A with a structure on which dynamics and field theory can be formulated to some extent in very much the same way we are used to from the geometrical arena underlying classical physical theories and models. In previous work, certain differential calculi on a commutative algebra exhibited relations with lattice structures, stochastics, and parametrized quantum theories. This motivated the present systematic investigation of differential calculi on commutative and associative algebras. Various results about their structure are obtained. In particular, it is shown that there is a correspondence between first order differential calculi on such an algebra and commutative and associative products in the space of 1-forms. An example of such a product is provided by the Ito calculus of stochastic differentials. For the case where the algebra A is freely generated by `coordinates' x^i, i=1,...,n, we study calculi for which the differentials dx^i constitute a basis of the space of 1-forms (as a left A-module). These may be regarded as `deformations' of the ordinary differential calculus on R^n. For n < 4 a classification of all (orbits under the general linear group of) such calculi with `constant structure functions' is presented. We analyse whether these calculi are reducible (i.e., a skew tensor product of lower-dimensional calculi) or whether they are the extension (as defined in this article) of a one dimension lower calculus. Furthermore, generalizations to arbitrary n are obtained for all these calculi.

The paper deals with non-commutative differential calculi. It contains the description of all homogeneous coordinate differential calculi on the quantum plane and of those on the two-generated Grassmannian algebra. In addition, the optimum algebra for the Pusz-Woronowicz calculus on the quantum hyperplane is found.

The transition from strong coupling to weak coupling in the SU(2) lattice gauge theory

The action of SU( N) lattice gauge theory in terms of the heat kernel on the group manifold

In a previous paper all bicovariant differential calculi on the two-parameter quantum group GLp,q(2) were determined. In this work the authors elaborate some of their properties and discuss relations with work by other authors. Furthermore, they show that there are two different ways in which bicovariant differential calculi on GLq(2) (where p=q) induce corresponding calculi on the quantum subgroup SLq(2). It is shown that on SLq(2) there are only two different bicovariant differential calculi. From these one obtains the 4D+or- calculi on SUq(2). The classical limit of the two differential calculi on SLq(2) is investigated revealing a relation with recent work on deformed differential calculi on commutative (function) algebras.

In this paper, a set of De Rham complexes of quantum group GLq(N) determined by one parameter r is given, and it is proven that the differential calculi on the quantum group GLq(N) given in this paper are bicovariant. The noncommutative differential calculi on the quantum groups SLq(N) and SUq(N) are also discussed.

The gauge invariance is an important phenomenon widely occurring in various matters with many-body interactions. The gauge theories are very important for understanding the evolution of fundamental physical processes in particle physics, high-energy physics, and condensed matter physics. In this work, the origin of nonlocal effects is inspected, and the contributions of nontrivial topological structures to physical properties are investigated in detail for both the three-dimensional (3D) Ising model and the 3D Z 2 lattice gauge model. Then, the exact solution for the 3D Z 2 lattice gauge theory is derived by the duality between the two models. The partition function, the spontaneous magnetization, the true range of correlation, and the critical point are rigorously derived for the 3D Z 2 lattice gauge theory. The critical exponents of the 3D Z 2 lattice gauge theory are in the same universality class as the 3D Ising model, which are α = 0, β = 3/8, γ = 5/4, δ = 13/3, η = 1/8, and ν = 2/3. Several fundamental issues, such as dimensionality, duality, symmetry, manifold and degenerate states, are investigated for these many-body interacting spin systems. The connections with superfluid, superconductors, particle physics, etc. are evaluated. Furthermore, physical significances and mathematical aspects of the 3D Z 2 lattice gauge theory are discussed with respect to topology, geometry, and algebra. The present results for the 3D Z 2 lattice gauge theory are helpful for figuring out the basic features of 3D lattice gauge theories with other symmetries, such as U(1), SU(2), and SU(3). This work shines a light on the interdisciplinarity between many-body interacting systems, algebra, topology, and geometry.

A numerical simulation of quenched SU(2) lattice gauge theory

Ceci est le second volet d'une série de deux articles visant à construire et étudier des groupes de Galois motiviques dans le cadre des motifs triangulés. Ces groupes de Galois motiviques ont été construits dans le premier volet et leurs algèbres de fonctions régulières ont été décrites explicitement en termes de formes différentielles ou de cycles algébriques. Dans le présent article, nous avons regroupé des compléments importants au premier volet. Dans une première partie, nous décrivons le lien entre le groupe de Galois motivique et le groupe de Galois usuel d'un sous-corps de 𝔻. Dans une deuxième partie, nous développons les bases d'une théorie de la ramification pour les groupes de Galois motiviques en construisant des groupes de décomposition et d'inertie motiviques associés à une place géométrique. On introduit également la notion de groupe de Galois motivique relatif pour une extension K / k $K/k$ qui mesure la différence entre les groupes de Galois motiviques de k et K. Ce dernier s'avère plus accessible que son analogue absolu. En effet, on montrera que c'est un quotient du complété pro-algébrique du pro-groupe fondamental topologique de la pro-variété hom k ( K , ℂ ) $\hom _k(K,\mathbb {C})$ , du moins lorsque l'extension K / k $K/k$ est de type fini.

Motivated by the sign problem, we calculate the effective Polyakov line action corresponding to certain SU(3) lattice gauge theories on a ${16^3 \times 6}$ lattice via the "relative weights" method introduced in our previous articles. The calculation is carried out at $\beta=5.6,5.7$ for the pure gauge theory, and at $\beta=5.6$ for the gauge field coupled to a relatively light scalar particle. In the latter example we determine the effective theory also at finite chemical potential, and show how observables relevant to phase structure can be computed in the effective theory via mean field methods. In all cases a comparison of Polyakov line correlators in the effective theory and the underlying lattice gauge theory, computed numerically at zero chemical potential, shows accurate agreement down to correlator magnitudes of order $10^{-5}$. We also derive the effective Polyakov line action corresponding to a gauge theory with heavy quarks and large chemical potential, and apply mean field methods to extract observables.

Based on an interpretation of the quark–lepton symmetry in terms of the unimodularity of the color group SU(3) and on the existence of 3 generations, we develop an argumentation suggesting that the “finite quantum space” corresponding to the exceptional real Jordan algebra of dimension 27 (the Euclidean Albert algebra) is relevant for the description of internal spaces in the theory of particles. In particular, the triality which corresponds to the 3 off-diagonal octonionic elements of the exceptional algebra is associated to the 3 generations of the Standard Model while the representation of the octonions as a complex 4-dimensional space C⊕C3 is associated to the quark–lepton symmetry (one complex for the lepton and 3 for the corresponding quark). More generally it is suggested that the replacement of the algebra of real functions on spacetime by the algebra of functions on spacetime with values in a finite-dimensional Euclidean Jordan algebra which plays the role of “the algebra of real functions” on the corresponding almost classical quantum spacetime is relevant in particle physics. This leads us to study the theory of Jordan modules and to develop the differential calculus over Jordan algebras (i.e. to introduce the appropriate notion of differential forms). We formulate the corresponding definition of connections on Jordan modules.

A continuum limit of the chiral Jacobian in lattice gauge theory

We introduce a large class of bicovariant differential calculi on any quantum group A, associated to Ad-invariant elements. For example, the deformed trace element on SLq (2) recovers Woronowicz's 4D ± calculus. More generally, we obtain a class of differential calculi on each quantum group A(R), based on the theory of the corresponding braided groups B(R). Here R is any regular solution of the QYBE.

Does asymptotic freedom shine on the lattice?