Hiroyuki Hata

Baryons from Instantons in Holographic QCD

We consider aspects of dynamical baryons in a holographic dual of QCD that is formulated on the basis of a D4/D8-brane configuration. We construct a soliton solution carrying a unit baryon number and show that it is obtained as an instanton solution of four-dimensional Yang-Mills theory with fixed size. The Chern-Simons term on the flavor D8-branes plays a crucial role of protecting the instanton from collapsing to zero size. By quantizing the collective coordinates of the soliton, we derive the baryon spectra. Negative-parity baryons as well as baryons with higher spins and isospins can be obtained in a simple manner.

Manifestly covariant field theory of interacting string I

Abstract A manifestly covariant field theory is constructed for the interacting bosonic open string. A very simple string action is presented which is invariant under an inhomogeneous nilpotent BRS transformation. The on-shell scattering amplitudes in this theory reproduce the Koba-Nielsen amplitudes at the tree level, aside from a contributions from a necessary quartic interaction term.

BRST invariance of the non-perturbative vacuum in bosonic open string field theory

Tachyon condensation on a bosonic D-brane was recently demonstrated numerically in Wittens open string field theory with level truncation approximation. This non-perturbative vacuum, which is obtained by solving the equation of motion, has to satisfy furthermore the requirement of BRST invariance. This is indispensable in order for the theory around the non-perturbative vacuum to be consistent. We carry out the numerical analysis of the BRST invariance of the solution and find that it holds to a good accuracy. We also mention the zero-norm property of the solution. The observations in this paper are expected to give clues to the analytic expression of the vacuum solution.

Skew-symmetric tensor gauge field theory dynamically realized in the QCD U(1) channel

Abstract It is shown that, in order for the U(1) Goldstone boson to decouple from the physical sector, a third rank skew-symmetric tensor gauge field theory has to be realized dynamically by asymptotic fields of bound states in QCD. The abelian-like gauge invariance of this tensor gauge theory is just a realization of the original QCD gauge (BRS) invariance which hence assures the decoupling of all the bound-state modes by the “quarlet mechanism”. A general procedure for fixing gauges in such types of skew-symmetric tensor gauge theories is also presented.

3-STRING JUNCTION AND BPS SATURATED SOLUTIONS IN SU(3) SUPERSYMMETRIC YANG-MILLS THEORY

Abstract We construct BPS saturated regular configurations of N =4 SU(3) supersymmetric Yang-Mills theory carrying non-parallel electric and magnetic charges. These field theory BPS states correspond to the string theory BPS states of 3-string junctions connecting three different D3-branes by regarding the N =4 supersymmetric Yang-Mills theory as an effective field theory on parallel D3-branes.

Pregeometrical String Field Theory: Creation of Space-time and Motion

Abstract A space-time-metric-independent and gauge-invariant formulation of closed-string field theory is proposed. The action contains no kinetic term and consists solely of a cubic term in the string field. The kinetic term can be generated through the condensation of an infinitesimally small string.

Brane Configuration from Monopole Solution in Non-Commutative Super Yang-Mills Theory

We study the structure of the monopole configuration in U(2) non-commutative super Yang-Mills theory. Our analysis consists of two steps: solving the BPS equation and then the eigenvalue equation in the non-commutative space. Calculation to the first non-trivial order in the non-commutativity parameter θ shows that the monopole exhibits a certain non-locality. This structure is precisely the one expected from the recent predictions by the brane-configuration technique.

Stereoselective enzymatic oxidation and reduction system for the production of D(−)-pantoyl lactone from a racemic mixture of pantoyl lactone

Abstract A novel enzymatic process for the synthesis of d (−)-pantoyl lactone from a racemic mixture of pantoyl lactone is described. The process involves the stereospecific oxidation of the l (+)-isomer of pantoyl lactone to ketopantoyl lactone followed by its asymmetric reduction to the d (−)-isomer. The oxidation is carried out with cells of Nocardia asteroides AKU 2103 as the catalyst, which convert only the l (+)-isomer of pantoyl lactone to ketopantoyl lactone without any modification of the remaining d (−)-isomer. With 80 g l −1 dl -pantoyl lactone as the substrate, >90% of the added l (+)-isomer was converted to ketopantoyl lactone under the optimum reaction conditions. The ketopantoyl lactone that accumulated in the reaction mixture was almost specifically converted to the d (−)-isomer of pantoyl lactone on incubation with cells of Candida parapsilosis IFO 0784. Since this process is simple and requires no reracemization step, which is necessary for conventional chemical resolution, it is highly advantageous for the practical synthesis of d (−)-pantoyl lactone.

Test of the absence of kinetic terms around the tachyon vacuum in cubic string field theory

It has been conjectured that the bosonic open string theory around the non-perturbative tachyon vacuum has no open string dynamics at all. We explore, in the cubic open string field theory with level truncation approximation, the possibility that this conjecture is realized by the absence of kinetic terms of the string field fluctuations. We study the kinetic terms with two and four derivatives for the lower level scalar modes as well as their BRST transformation properties. The behavior of the coefficients of the kinetic terms in the neighborhood of the non-perturbative vacuum supports our expectation that the BRST invariant scalar component lacks its kinetic term.

Multi-Pronged Strings and BPS Saturated Solutions in SU(N) Supersymmetric Yang-Mills Theory

Extending our previous work on SU(3), we construct spherically symmetric BPS saturated regular configurations of N = 4 SU(N) supersymmetric Yang-Mills theory preserving 14 supersymmetry, and investigate their features. We also give exact solutions in the case some of the free parameters of the general solutions take certain values. These field theory BPS states correspond to the string theory BPS states of multi-pronged strings connecting N different D3-branes by regarding the N = 4 supersymmetric Yang-Mills theory as an effective field theory on parallel D3-branes. We compare our solutions with multi-pronged strings in the string picture.