arXiv subjects
Publications and source records attributed to Yoji Michishita.
We consider first order symmetry operators for the equations of motion of differential $p$-form fields in general $D$-dimensional background geometry of any signature for both massless and massive cases. For $p=1$ and $p=2$ we give the general forms of the symmetry operators. Then we find a class of symmetry operators for arbitrary $p$ and $D$, which is naturally suggested by the lower $p$ results.
We determine the general form of the first order linear symmetry operators for the linearized field equation of metric perturbations in the spacetimes of dimension D>=4. Apart from the part derived easily from the invariance under general coordinate transformations, we find a part consisting of a Killing-Yano 3-form.
We consider first order linear operators commuting with the operator appearing in the linearized equation of motion of Rarita-Schwinger fields which comes directly from the action. First we consider a simplified operator giving an equation equivalent to the original equation, and classify first order operators commuting with it in four dimensions. In general such operators are symmetry operators of the original operator, but we find that some of them commute with it. We extend this result in four dimensions to arbitrary dimensions and give first order commuting operators constructed of odd rank Killing-Yano and even rank closed conformal Killing-Yano tensors with additional conditions.
We give a solution to the classical master equation of D=11 supergravity in the conventional component formulation. Based on a careful investigation of the symmetry algebra including terms proportional to the equation of motion, we construct an explicit expression of the master action in an order-by-order manner.
It has been known that SU(N) supermembrane matrix model has continuous energy spectrum, and it has also been conjectured that it has a normalizable energy eigenstate. Assuming that there exists a normalizable energy eigenstate for each N, we show that there exists a branch of continuous energy spectrum for each partition of N.
The explicit, near the origin, form of the ground state of the SU(2) supermembrane matrix model is studied. We evaluate the 2nd order terms of the Taylor expansion of the wave-function, which together with the 0th and the 1st order terms can be used to determine other terms by recurrence equations coming from the Schroedinger equation.
We investigate the structure of the spectrum of states in D=2 SU(N) supersymmetric Yang-Mills matrix quantum mechanics, which is a simplified model of Matrix theory. We compute the thermal partition function of this system and give evidence for the correctness of naively conjectured structure of the spectrum. It also suggests that Claudson-Halpern-Samuel solution is the unique eigenfunction of simultaneously diagonalizable hermitian operators, and we show that it is true in N=3 and N=4 cases.
We consider decomposition of coordinate independent states into SO(9)xSU(2) representations in SU(2) Matrix theory. To see what and how many representations appear in the decomposition, we compute the character, which is given by a trace over the coordinate independent states, and decompose it into the sum of products of SO(9) and SU(2) characters.
We investigate coordinate independent SO(9) vector states in SU(2) Matrix theory. There are 36 vector states, and we determine what representations of SU(2) they are decomposed into. Among them we find a unique set of states transforming in adjoint representation. We show that this set of states can appear as the linear term in the coordinate matrices in Taylor expansion of zero energy bound state wavefunction around the origin i.e. it satisfies the condition of full supersymmetry.
We construct a kappa symmetric WZNW model for the OSp(2|2) supergroup, whose bosonic part is AdS3xS1 space. The field equation gives the chiral current conservation and the right/left factorization is shown after the kappa symmetry is fixed. The right-moving modes contain both bosons and fermions while the left-moving modes contain only bosons.
We investigate analytic solutions to Witten's bosonic string field theory and Berkovits' WZW-type superstring field theory. We construct solutions with parameters out of simpler ones, using a commutative monoid that includes the family of wedge states. Our solutions are generalizations of solutions for marginal deformations by nonsingular currents, and can also reproduce Schnabl's tachyon vacuum solution in bosonic string field theory. This implies that such known solutions are generated from simple solutions which are based on the identity state. We also discuss gauge transformations and induced field redefinitions for our solutions in both bosonic and super string field theory.
We investigate classical solutions in closed bosonic string field theory and heterotic string field theory that are obtained order by order starting from solutions of the linearized equations of motion, and we discuss the ``field redefinitions'' which relate massless fields in the string field theory side and the low energy effective theory side. Massless components of the string field theory solutions are not corrected and from them we can infer corresponding solutions in the effective theory: the chiral null model and the pp-wave solution with B-field, which have been known to be alpha'-exact. These two sets of solutions in the two sides look slightly different because of the field redefinitions. It turns out that T-duality is a useful tool to determine them: We show that some part of the field redefinitions can be determined by using the correspondence between T-duality rules in the two sides, irrespective of the detail of the interaction terms and the integrating-out procedure. Applying the field redefinitions, we see that the solutions in the effective theory side are reproduced from the string field theory solutions.
In Witten's open cubic bosonic string field theory and Berkovits' superstring field theory we investigate solutions of the equations of motion with appropriate source terms, which correspond to Callan-Maldacena solution in Born-Infeld theory representing fundamental strings ending on the D-branes. The solutions are given in order by order manner, and we show some full order properties in the sense of (alpha)'-expansion. In superstring case we show that the solution is 1/2 BPS in full order.
In a way analogous to type IIB supergravity, we give a covariant action for the fermion field supplemented with a constraint which should be imposed on equations of motion, in Berkovits' open superstring field theory. From this action we construct Feynman rules for computing perturbative amplitudes for fermions. We show that on-shell tree level 4-point amplitudes computed by using these rules coincide with those of the first quantization formalism.
We study gauge invariant quantities in the open superstring field theory proposed by Berkovits, extending the precedent discussion in bosonic string field theory. Our gauge invariants are ``on-shell''. As its applications, we define quantities which are expected to be related to the U(1) field strength -- a RR coupling and a ``component'' of the string field equation of motion, and consider their naive extensions to off-shell. Order by order calculations show that the field strength extracted from the RR coupling is not gauge invariant, while from the component of the equation of motion we obtain an off-shell field strength which is gauge invariant under full gauge transformation if on-shell, and under linearized gauge transformation even off-shell.
We investigate boundary conditions for open strings in NSNS and RR pp-wave backgrounds constructed by Russo and Tseytlin, which are S-dual to each other. We show that if we do not turn on any boundary term (i.e. gauge field), D-branes in the RR background cannot move away from the origin in most cases, while those in the NSNS background can move anywhere. We construct RR counterparts of D3-branes in the NSNS background as D3-branes with gauge fluxes and show that indeed they can move anywhere, in accord with S-duality.
We consider a D-brane probe in unstable string background associated with flux branes. The twist in spacetime metric reponsible for the supersymmetry breaking is shown to manifest itself in mixing of open Wilson lines with the phases of some adjoint matter fields, resulting in a nonlocal and nonsupersymmetric form of Yang-Mills theory as the probe dynamics. This provides a setup where one can study fate of a large class of unstable closed string theories that include as a limit type 0 theories and various orbifolds of type II and type 0 theories. We discuss the limit of ${\bf C}/Z_n$ orbifold in some detail and speculate on couplings with closed string tachyons.
We investigate D-branes with maximal symmetry on general group manifolds in terms of boundary states and effective actions. We show that in large $k$ limit boundary states with an suitable Wilson line form boundary states of the other types of D-branes, extending the known fact in SU(2) case. We also show that fluctuation mass spectrum around D-brane solutions of the effective action agrees with that of boundary CFT in large $k$ limit.