Browsing by Author "Ho, Pei-Ming"

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Comments on the high energy limit of bosonic open string theory
(2006-08-14)
Chan, Chuan-Tsung
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Ho, Pei-Ming
;
Lee, Jen-Chi
;
Teraguchi, Shunsuke
;
Yang, Yi
In previous works, ratios among four-point scattering amplitudes at the leading order in the high-energy limit were derived for the bosonic open string theory. The derivation was based on Ward identities derived from the decoupling of zero-norm states and was purely algebraic. The only assumption of the derivation was that the momentum polarization can be approximated by the longitudinal polarization at high energies. In this paper, using the decoupling of spurious states, we reduce this assumption to a much weaker one which can be easily verified by simple power counting in most cases. For the special cases which are less obvious, we verify the new assumption for an example by saddle-point approximation. We also provide a new perspective to our previous results in terms of DDF states. In particular, we show that, by using DDF states, one can easily see that there is only one independent high energy scattering amplitude for each fixed mass level. (c) 2006 Elsevier B.V. All rights reserved.
Zero-norm states and stringy symmetries
(2006)
Chan, Chuan-Tsung
;
Ho, Pei-Ming
;
Lee, Jen-Chi
;
Teraguchi, Shunsuke
;
Yi-Yang
We identify spacetime symmetry charges of string theory from an infinite number of zero-norm states (ZNS) with arbitrary high spin in the old covariant first quantized string spectrum. We give various evidences to support this identification. These include massive sigma-model calculation, Witten string field theory calculation, 2D string theory calculation and, most importantly, three methods of high-energy stringy scattering amplitude calculation. The last calculations explicitly prove Gross\'s conjectures in 1988 on high energy symmetry of string theory.