科研之友
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摘要
We describe two interesting effects in wormhole physics. First, we find that a genuinely charged matter source of gravity and electromagnetism may appear electrically neutral to an external observer -a phenomenon opposite to the famous Misner-Wheeler " charge without charge" effect. We show that this phenomenon takes place when coupling a bulk gravity/ nonlinear-gauge-field system self-consistently to a codimensionone charged lightlike brane as a matter source. The "charge-hiding" effect occurs in a self-consistent wormhole solution of the above coupled gravity/ nonlinear-gauge-field/ lightlike-brane system which connects a noncompact "universe," comprising the exterior region of Schwarzschild-(anti-) de Sitter (or purely Schwarzschild) black hole beyond the internal (Schwarzschild) horizon, to a Levi-Civita-Bertotti-Robinson-type ("tube-like") " universe" with two compactified dimensions via a wormhole "throat" occupied by the charged lightlike brane. In this solution the whole electric flux produced by the charged lightlike brane is expelled into the compactified Levi-Civita-Bertotti-Robinsontype universe" and, consequently, the brane is detected as neutral by an observer in the Schwarzschild-(anti-) de Sitter "universe." Next, the above "charge-hiding" solution can be further generalized to a truly charge-confining wormhole solution when we couple the bulk gravity/ nonlinear-gauge-field system self-consistently to two separate codimension-one charged lightlike branes with equal in magnitude but opposite charges. The latter system possesses a "two-throat" wormhole solution, where the "left-most" and the "right-most" "universes" are two identical copies of the exterior region of the neutral Schwarzschild-de Sitter black hole beyond the Schwarzschild horizon, whereas the " middle" "universe" is of generalized Levi-Civita-Bertotti-Robinson "tube-like" form with geometry dS2 x S2 (dS2 being the two-dimensional de Sitter space). It comprises the finite-extent intermediate region of dS2 between its two horizons. Both "throats" are occupied by the two oppositely charged lightlike branes and the whole electric flux produced by the latter is confined entirely within the middle finite-extent "tube-like" " universe." A crucial ingredient is the special form of the nonlinear gauge field action, which contains both the standard Maxwell term as well as a square root of the latter. This theory was previously shown to produce a QCD-like confining dynamics in flat space-time.
- 出版日期2011-12-20
