16459641
Interaction between Noncommutative Open Strings and Closed-String Tachyons
We construct a vertex operator that describes the emission of a ground-state tachyon of a closedstring out of a noncommutative open string. Such a vertex operator is shown to exist only when the momentum of the closed-string tachyon is subject to some constraints coming from the background B field. When the non-zero background B fieldis lying only on a D-brane, and both ends of the open string are on the D-brane, the closed-string tachyon is emittedfrom the open string in an orthogonal d irection to the D-brane. The vertex operator has a multiplicative coupling constant g(σ) which depends on σ as g(σ) = sin 2 σ in 0 ≤ σ ≤ π. This behavior is the same as in the ordinary B = 0 case.
120575563
Unitarity, Factorization Theorem and Removal of Level Degeneracy in Dual Resonance Model
It is shown that, by using a unitarity relation for a many-body scattering amplitude, a Regge residue appearing in this amplitude is factorized. This theorem is a generalization of that in the t~o-body case. According to this theorem the famous level degeneracy in dual resonance models is expected to be removed, if unitarity is taken into account. We propose an eguation for removing the degeneracy, which has a close resemblance to that in the quantum mechanical perturbation theory with degenerate levels. shown that the number of resonant states with mass Sn, sn being defined by n =a (sn), is given by exp (aVn), (a= 2n/ -/6), for a large n. In other words, the N-point Veneziano formula has the extremely large number of degenerate levels. On the other hand, we can see in § 2 that, by using a unitarity relation for a many-body scattering amplitude, a Regge residue appearing in this amplitude is factorized, that is, the number of the states having mass sn is only one. This theorem is a generalization of that in the two-body case. 2 > The Veneziano amplitude violates unitarity in a way similar to that in which the Born approximation does in the usual Feynman-Dyson theory. It may be expected, therefore, that the level degeneracy in the dual resonance model will be removed if unitarity is taken into account. If, for the purpose of imposing unitarity, we sum up all the higher order diagrams in the framework of the operator formalism, the poles of the amplitude appear as poles of the "clothed propagator". Though the self-energy part of this clothed propagator is strongly divergent, we expect that some kind of renormalization procedure will be· possible. 3 > (We do not consider this procedure in this paper.) ln order to obtain the "observed" masses, that is, the zeros of the inverse propagator, we propose in § 3 a method very similar to that in the quantum mechanical perturbation theory with degenerate levels.
122084216
Operator Formalism of the Dual Resonance Model with Different Trajectories
In the dual resonance model the generalized harmonic oscillator formalism is constructed when relevant particles lie on different trajectories. Requiring the factorization in the sense of the operator method, one can see that the Regge intercepts are expressed in terms of quark quantum numbers. Propagator, general vertex, gauge operator and so on, appearing in the usual dual resonance model with a single trajectory, are redefined. The duality of the four­ point tree diagram between general non-spurious virtual states can also be shown.
121289650
Schwarzian Connections in the Krichever-Novikov Algebra
In the local operator approach to higher-genus Riemann surface we point out an importance of
96438339
Sum Rules Based on Khuri Amplitudes and Degeneracy of Regge Trajectories
l) have proposed an idea that the Pomeranchuk trajec­ tory is mostly built (in the sense of finite-energy sum rule) from the nonresonating background part of the low-energy amplitude while all other trajectories; including pI, are mainly generated by the low-energy resonances. They have formulated their idea by using the conventional discrete moment sum rules for crossing even· (or odd) amplitudes. In this paper we derive in § 2 a finite-energy sum rule (FESR) based on the Khuri amplitude. 2 ) Crossing relations of the amplitudes are not used in this FESR, contrary to the case of the usual FESR. The new FESR is applied in § 3 to KN and nn scatterings. Disregarding the Pomeranchuk contribution, ac­ cording to the idea of Harari et aI., we show that pI, (J), P and R trajectories are degenerate, i.e. *)
123170513
Color-Magnetic Permeability of QCD Vacuum
In a preYious papern we have shown that the true ground-state yacuum of QCD (quantum chromodynamics) has lower energy than the "perturbative vacuum." The MIT bag constant may be given by the energy density difference between the perturbative vacuum and the true ground-state vacuum of QCD, because in the MIT bag model the perturbative vacuum is used inside the bag, while on the outside we have for the fields an impenetrable vacuum. In the present paper we calculate the color-magnetic permeability lie of the QCD true vacuum and show this value to be 1/2 within the quark-one-loop approximation. A gl uon-loop contribution to the QCD vacuum is shown to be neglected when the number of quark flavor is large. If lie= 0, the vacuum is the perfect diamagnet so that quarks and gluons may be confined inside Abrikosov flux lines by the Meissner effect. However, m view of our result fie= 1/2 this confinement is still imperfect at this stage. We begin with a review of our previous work. We adopt the following expression of the SU (2) background gauge field:
120181374
The study of hypernuclei with heavy ion beams at GSI
The international HypHI collaboration is proposing a hypernuclear spectroscopy with stable heavy ion beams and rare isotope beams at GSI and FAIR in order to study neutron/proton rich hypernuclei and eventually to measure hypernuclear magnetic moments. As Phase 0 of the HypHI project, we propose the feasibility study of heavy ion induced hypernuclear spectroscopy by observing a mesonic weak decay from H Λ 3 , H Λ 4 and He Λ 5 with 6Li beams at 2 A GeV impinging on a 12C target. The physics motivations, experimental setup and the expected results will be discussed.