Space/time non-commutativity and causality

Citation
N. Seiberg et al., Space/time non-commutativity and causality, J HIGH EN P, 2000(6), 2000, pp. NIL_830-NIL_845
Citations number
14
Categorie Soggetti
Physics
Journal title
JOURNAL OF HIGH ENERGY PHYSICS
ISSN journal
10298479 → ACNP
Volume
2000
Issue
6
Year of publication
2000
Pages
NIL_830 - NIL_845
Database
ISI
SICI code
1029-8479(200006)2000:6<NIL_830:SNAC>2.0.ZU;2-K
Abstract
Field theories based on non-commutative spacetimes exhibit very distinctive non-local effects which mix the ultraviolet with the infrared in bizarre w ays. In particular if the time coordinate is involved in the non-commutativ ity the theory seems to be seriously acausal and inconsistent with conventi onal hamiltonian evolution. To illustrate these effects we study the scatte ring of wave packets in a field theory with space/time non-commutativity. I n this theory we find effects which seem to precede their causes and rigid rods which grow instead of Lorentz contract as they are boosted. These fiel d theories are evidently inconsistent and violate causality and unitarity. On the other hand open string theory in a background electric field is expe cted to exhibit space/time non-commutativity. This raises the question of w hether they also lead to acausal behavior. We show that this is not the cas e. Stringy effects conspire to cancel the acausal effects that are present for the non-commutative field theory.