Invariant Regularization of Supersymmetric Chiral Gauge Theory

We present a regularization scheme which respects the supersymmetry and the maximal background gauge covariance in supersymmetric chiral gauge theories. When the anomaly cancellation condition is satisfied, the effective action in the superfield background field method automatically restores the gauge invariance without counterterms. The scheme also provides a background gauge covariant definition of composite operators that is especially useful in analyzing anomalies. We present several applications: The minimal consistent gauge anomaly; the super-chiral anomaly and the superconformal anomaly; as the corresponding anomalous commutators, the Konishi anomaly and an anomalous supersymmetric transformation law of the supercurrent (the ``central extension'' of N=1 supersymmetry algebra) and of the R-current.Comment: uses PTPTeX, 16 pages, based on the invited talk in the workshop on ``Gauge Theory and Integrable Models,'' January 1999, Kyot

A no-go theorem for the Majorana fermion on a lattice

A variant of the Nielsen--Ninomiya no-go theorem is formulated. This theorem states that, under several assumptions, it is impossible to write down a doubler-free Euclidean lattice action of a single Majorana fermion in $8k$ and $8k+1$ dimensions.Comment: 8 pages, uses PTPTeX. The final version to appear in Prog. Theor. Phy

Remark on the energy-momentum tensor in the lattice formulation of 4D N=1\mathcal{N}=1 SYM

In a recent paper, arXiv:1209.2473 \cite{Suzuki:2012gi}, we presented a possible definition of the energy-momentum tensor in the lattice formulation of the four-dimensional $\mathcal{N}=1$ supersymmetric Yang--Mills theory, that is conserved in the quantum continuum limit. In the present Letter, we propose a quite similar but somewhat different definition of the energy-momentum tensor (that is also conserved in the continuum limit) which is superior in several aspects: In the continuum limit, the origin of the energy automatically becomes consistent with the supersymmetry and the number of renormalization constants that require a (non-perturbative) determination is reduced to two from four, the number of renormalization constants appearing in the construction in Ref. \cite{Suzuki:2012gi}.Comment: 13 pages, the final version to appear in Phys. Lett.

Calculation Rule for Aoyama-Tamra's Prescription for Path Integral with Quantum Tunneling

We derive a simple calculation rule for Aoyama--Tamra's prescription for path integral with degenerated potential minima. Non-perturbative corrections due to the restricted functional space (fundamental region) can systematically be computed with this rule. It becomes manifest that the prescription might give Borel summable series for finite temperature (or volume) system with quantum tunneling, while the advantage is lost at zero temperature (or infinite volume) limit.Comment: phyzzx, 8 page

Background field method in the gradient flow

In perturbative consideration of the Yang--Mills gradient flow, it is useful to introduce a gauge non-covariant term ("gauge-fixing term") to the flow equation that gives rise to a Gaussian damping factor also for gauge degrees of freedom. In the present paper, we consider a modified form of the gauge-fixing term that manifestly preserves covariance under the background gauge transformation. It is shown that our gauge-fixing term does not affect gauge-invariant quantities as the conventional gauge-fixing term. The formulation thus allows a background gauge covariant perturbative expansion of the flow equation that provides, in particular, a very efficient computational method of expansion coefficients in the small flow time expansion. The formulation can be generalized to systems containing fermions.Comment: 19 pages, the final version to appear in PTE