95 research outputs found
Higher-group structure in lattice Abelian gauge theory under instanton-sum modification
We consider the gauge theory on a four-dimensional torus, where the
instanton number is restricted to an integral multiple of . This theory
possesses the nontrivial higher-group structure, which can be regarded as a
generalization of the Green--Schwarz mechanism, between -form
and -form symmetries. Here, is a subgroup of
the center of~. Following the recent study of the lattice construction of
the principal bundle, we examine how such a structure is
realized on the basis of lattice regularization.Comment: 16 pages, to appear in EPJ
Theory of Ferromagnetism in Ca1-xLaxB6
Novel ferromagnetism in CaLaB is studied in terms of the
Ginzburg-Landau theory for excitonic order parameters, taking into account
symmetry of the wavefunctions. We found that the minima of the free energy
break both inversion and time-reversal symmetries, while the product of these
two remains preserved. This explains various novelties of the ferromagnetism
and predicts a number of magnetic properties, including the magnetoelectric
effect, which can be tested experimentally.Comment: 5 pages, accepted for publication in Phys.Rev.Let
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