Hitoshi Nishino

Stability analysis of p-adic string solitons

Abstract An effective field theory built on the tachyonic vacuum of the p -adic bosonic string was shown by Brekke et al. to possess soliton solutions of positive energy in a shifted lower-energy vacuum. It is shown here that such solitons should be interpreted not as real-mass particles but as vacuum decay to yet a third vacuum of unboundedly low energy.

Topological gauging of N=16 supergravity in three-dimensions

We present a topologically non-trivial generalization of gauged N=16 supergravity on the coset E_8 / SO(16) in three-dimensions. This formulation is based on a combination of BF-term and a Chern-Simons term for an SO(16) gauge field A_m{}^{I J}. The fact that an additional vector field B_m{}^{I J} is physical and propagating with couplings to sigma-model fields makes our new gauging non-trivial and different from the conventional one. Even though the field strength of the A_m{}^{I J}-field vanishes on-shell, the action is topologically non-trivial due to non-vanishing pi_3-homotopy. We also present an additional modifications by an extra Chern-Simons term. As by-products, we give also an application to N=9 supergravity coupled to a sigma-model on the coset F_4 / SO(9), and a new BF-Chern-Simons theory coupled to ^forall N extended supergravity.

Dimensional reduction of the Green-Schwarz superstring on a Calabi-Yau manifold

Compactifying the ten-dimensional (D = 10), N = 1 Green-Schwarz superstring on a six-dimensional internal Calabi-Yau manifold, we obtain a D = 4, N = 1 Green-Schwarz superstring model. A consistent dimensional reduction rule is established in superspace. The problem of the compactification of the supervielbien is avoided by using the technique of background-quantum splitting in the Green-Schwarz σ-model. The satisfaction of the condition of vanishing for the σ-model β-functions in D = 10 guarantees the consistency of our dimensional reduction scheme. Quantum consistency of the resulting model is also checked by the satisfaction of the condition of vanishing for the β-functions directly in D = 4.

Sarks as additional fermions

An extension of the standard model is proposed. The gauge group is SU(2)X ⊗ SU(3)C ⊗ SU(2)S ⊗ U(1)Q, where all gauge symmetries are unbroken. The colour and electric charge are combined with SU(2)S which becomes strongly coupled at approximately 500 GeV and binds preons to form fermionic and vector bound states. The usual quarks and leptons are singlets under SU(2)X but additional fermions, called sarks. transform under it and the electroweak group. The present model explains why no more than three light quark-lepton families can exist. Neutral sark baryons, called narks, are candidates for the cosmological dark matter having the characteristics designed for WIMPS. Further phenomenological implications of sarks are analyzed i including electron-positron annihilation. Z0 decay, flavor-changing neutral currents. baryon-number non-conservation, sarkonium and the neutron electric dipole moment.

ß-function approach to the p-adic string☆

Abstract Using a σ -model approach to the p adic string in the presence of tachyonic background fields, we compute the s -function corresponding to a discrete scale invariance. It is shown, up to second order in tachyon fields, that the requirement of vanishing s -function reproduces the tachyonic field equation previously derived from the analysis of p -adic tree amplitudes.

N=4supersymmetric Yang-Mills multiplet in nonadjoint representations

We formulate a theory for an N=4 supersymmetric Yang-Mills multiplet in a nonadjoint representation R of SO(N), as an important application of our recently proposed model for N=1 supersymmetry. This system is obtained by dimensional reduction from an N=1 supersymmetric Yang-Mills multiplet in a nonadjoint representation in ten dimensions. The consistency with supersymmetry requires that a nonadjoint representation R with the indices i,j,... satisfy the three conditions {eta}{sup ij}={delta}{sup ij}, (T{sup I}){sup ij}=-(T{sup I}){sup ji}, and (T{sup I}){sup [ij|}(T{sup I}){sup |k]l}=0 for the metric {eta}{sup ij} and the generators T{sup I}, which are the same as the N=1 case.

ℵ0hypergravity in three dimensions

We construct hypergravity theory in three-dimensions with the gravitino {psi}{sub {mu}}{sub m{sub 1}}{sub {center_dot}}{sub {center_dot}}{sub {center_dot}}{sub m{sub n}}{sup A} with an arbitrary half-integral spin n+3/2, carrying also the index A for certain real representations of any gauge group G. The possible real representations are restricted by the condition that the matrix representation of all the generators are antisymmetric: (T{sup I}){sup AB}=-(T{sup I}){sup BA}. Since such a real representation can be arbitrarily large, this implies aleph{sub 0} hypergravity with infinitely many (aleph{sub 0}) extended local hypersymmetries.

Aleph_null Hypergravity in Three-Dimensions

We construct hypergravity theory in three-dimensions with the gravitino {psi}{sub {mu}}{sub m{sub 1}}{sub {center_dot}}{sub {center_dot}}{sub {center_dot}}{sub m{sub n}}{sup A} with an arbitrary half-integral spin n+3/2, carrying also the index A for certain real representations of any gauge group G. The possible real representations are restricted by the condition that the matrix representation of all the generators are antisymmetric: (T{sup I}){sup AB}=-(T{sup I}){sup BA}. Since such a real representation can be arbitrarily large, this implies aleph{sub 0} hypergravity with infinitely many (aleph{sub 0}) extended local hypersymmetries.

Wormhole effects on masses of vector and gravitino fields

Abstract We examine the effect of wormholes on the masses of vector and gravitino fields, by explicit harmonic expansions on S 4 in the unitary gauge after the (super) Higgs effect. We find that wormholes tend to destabilize any small masses of these fields, and drive the vector mass and the gravitino mass towards the wormhole scale.

Spontaneous gauge symmetry breaking in conformal theories of a four-dimensional superstring

Abstract We formulate a mechanism of spontaneous gauge symmetry breaking with continuous parameters, in the superconformal theory approach to four-dimensional superstring theories. As an example, we inspect the 1 9 -model with the breaking of the gauge group SO(26). Supersymmetry is unbroken, maintaining the zero cosmological constant, and realistic gauge groups such as E 8 ⊗ SU(3) ⊗ SU(2) ⊗ U(1) 11 are obtained after the gauge breaking for the 1 × 16 3 -model with three generations.