Constructing Nonabelian (1,0) Hypermultiplet Theories in Six Dimensions

We construct a class of nonabelian superconformal (1,0) hypermultiplet theories in six dimensions by introducing an abelian auxiliary field. The gauge fields of this class of theories are non-dynamical, and this class of theories can be viewed as Chern-Simons-matter theories in 6D.Comment: 5 pages, minor changes, reference adde

Spectral gap and logarithmic Sobolev constant for continuous spin systems

The aim of this paper is to study the spectral gap and the logarithmic Sobolev constant for continuous spin systems. A simple but general result for estimating the spectral gap of finite dimensional systems is given by Theorem 1.1, in terms of the spectral gap for one-dimensional marginals. The study of the topic provides us a chance, and it is indeed another aim of the paper, to justify the power of the results obtained previously. The exact order in dimension one (Proposition 1.4), and then the precise leading order and the explicit positive regions of the spectral gap and the logarithmic Sobolev constant for two typical infinite-dimensional models are presented (Theorems 6.2 and 6.3). Since we are interested in explicit estimates, the computations become quite involved. A long section (Section 4) is devoted to the study of the spectral gap in dimension one.Comment: 40 pages, 2 figure

Progress on Hardy-type Inequalities

This paper surveys some of our recent progress on Hardy-type inequa\-lities which consist of a well-known topic in Harmonic Analysis. In the first section, we recall the original probabilistic motivation dealing with the stability speed in terms of the $L^2$-theory. A crucial application of a result by Fukushima and Uemura (2003) is included. In the second section, the non-linear case (a general Hardy-type inequality) is handled with a direct and analytic proof. In the last section, it is illustrated that the basic estimates presented in the first two sections can still be improved considerably.Comment: 13 pages, 5 figures, Festschrift Masatoshi Fukushima: In Honor of Masatoshi Fukushima's Sanju. World Scientific, 201

Eigenvalues, inequalities and ergodic theory

This paper surveys the main results obtained during the period 1992-1999 on three aspects mentioned at the title. The first result is a new and general variational formula for the lower bound of spectral gap (i.e., the first non-trivial eigenvalue) of elliptic operators in Euclidean space, Laplacian on Riemannian manifolds or Markov chains (\S 1). Here, a probabilistic method-coupling method is adopted. The new formula is a dual of the classical variational formula. The last formula is actually equivalent to Poincar\'e inequality. To which, there are closely related logarithmic Sobolev inequality, Nash inequality, Liggett inequality and so on. These inequalities are treated in a unified way by using Cheeger's method which comes from Riemannian geometry. This consists of \S 2. The results on these two aspects are mainly completed by the author joint with F. Y. Wang. Furthermore, a diagram of the inequalities and the traditional three types of ergodicity is presented (\S 3). The diagram extends the ergodic theory of Markov processes. The details of the methods used in the paper will be explained in a subsequent paper under the same title.Comment: 6 page

Practical Criterion for Uniqueness of QQ-processes

The note begins with a short story on seeking for a practical sufficiency theorem for the uniqueness of time-continuous Markov jump processes, starting around 1977. The general result was obtained in 1985 for the processes with general state spaces. To see the sufficient conditions are sharp, a dual criterion for non-uniqueness was obtained in 1991. This note is restricted however to the discrete state space (then the processes are called $Q$-processes or Markov chains), for which the sufficient conditions just mentioned are showing at the end of the note to be necessary. Some examples are included to illustrate that the sufficient conditions either for uniqueness or for non-uniqueness are not only powerful but also sharp.Comment: 11 page

OSp(4|4) superconformal currents in three-dimensional N=4 Chern-Simons quiver gauge theories

We prove explicitly that the general D=3, N=4 Chern-Simons-matter (CSM) theory has a complete OSp(4|4) superconformal symmetry, and construct the corresponding conserved currents. We re-derive the OSp(5|4) superconformal currents in the general N=5 theory as special cases of the OSp(4|4) currents by enhancing the supersymmetry from N=4 to N=5. The closure of the full OSp(4|4) superconformal algebra is verified explicitly.Comment: 23 pages, published in PR

Symplectic Three-Algebra Unifying N=5,6 Superconformal Chern-Simons-Matter Theories

We define a 3-algebra with structure constants being symmetric in the first two indices. We also introduce an invariant anti-symmetric tensor into this 3-algebra and call it a symplectic 3-algebra. The general N=5 superconformal Chern-Simons-matter (CSM) theory with SO(5) R-symmetry in three dimensions is constructed by using this algebraic structure. We demonstrate that the supersymmetry can be enhanced to N=6 if the sympelctic 3-algebra and the fields are decomposed in a proper fashion. By specifying the 3-brackets, some presently known N=5, 6 superconformal theories are described in terms of this unified 3-algebraic framework. These include the N=5, Sp(2N) X O(M) CSM theory with SO(5) R-symmetry , the N=6, Sp(2N) X U(1) CSM theory with SU(4) R-symmetry, as well as the ABJM theory as a special case of U(M) X U(N) theory with SU(4) R-symmetry.Comment: 31 pages, minor changes, final results remain the sam

Criteria for Discrete Spectrum of 1D Operators

For discrete spectrum of 1D second-order differential/difference operators (with or without potential (killing), with the maximal/minimal domain), a pair of unified dual criteria are presented in terms of two explicit measures and the harmonic function of the operators. Interes\-tingly, these criteria can be read out from the ones for the exponential convergence of four types of stability studied earlier, simply replacing the `finite supremum' by `vanishing at infinity'. Except a dual technique, the main tool used here is a transform in terms of the harmonic function, to which two new practical algorithms are introduced in the discrete context and two successive approximation schemes are reviewed in the continuous context. All of them are illustrated by examples. The main body of the paper is devoted to the hard part of the story, the easier part but powerful one is delayed to the end of the paper.Comment: 31 pages, 1 figure in Commun. Math. Stat. (2015

OSp(5|4) Superconformal Symmetry of N=5 Chern-Simons Theory

We demonstrate that the general D=3, N=5 Chern-Simons matter theory possesses a full OSp(5|4) superconformal symmetry, and construct the corresponding superconformal currents. The closure of the superconformal algebra is verified in detail. We also show that the conserved OSp(6|4) superconformal currents in the general N=6 theory can be obtained as special cases of the OSp(5|4) currents by enhancing the R-symmetry of the N=5 theory from USp(4) to SU(4).Comment: 24 pages, minor changes, version published in Nucl.Phys.

Global algorithms for maximal eigenpair

This paper is a continuation of \ct{cmf16} where an efficient algorithm for computing the maximal eigenpair was introduced first for tridiagonal matrices and then extended to the irreducible matrices with nonnegative off-diagonal elements. This paper introduces two global algorithms for computing the maximal eigenpair in a rather general setup, including even a class of real (with some negative off-diagonal elements) or complex matrices.Comment: 20 page