膜间相互作用、开弦对产生和增强效应及其可能的实验探测

D-brane interaction, the open string pair production and its enhancement plus its possible detection

本文较为详细地介绍了作者之一及其合作者近期在TypeⅡ弦理论中有关D膜间相互作用,开弦对产生以及这种对产生在一定情况下的增强效应的系列研究工作.具体包括计算了带有一般世界体常数电磁场情况下平行放置且有一定间距的两张D膜间的相互作用,讨论了相关特性,比如相互作用的吸引或排斥情况.当其中至少一张膜带电场时,这种相互作用振幅通常有一个虚部,反映了该系统的一种不稳定性即开弦对的产生,并给出相应的衰变率和开弦对产生率.另外,探讨了这种开弦对产生率的增强效应,发现其与所加的电场和磁场的方向和大小相关联.当其中一个膜的空间维度为3,另一个膜的空间维度为1时,这种开弦对产生率可以大到人类实验室条件下得以检验.开弦对的产生率与两膜沿额外维方向的间距密切关联,如果假定弦理论的正确性及人类的4维时空可以看成一张D3膜的话,测量开弦对产生所给出的(比如)电流并验证其与所加电磁场的关系符合预言,由此可以检验额外维的存在性.同时,这也为弦理论提供了一种实验检验,并且这是一种无须将该理论紧化到四维时空的全新方式.

This review article reports the recent studies,based on a series of publications by one of the present authors along with his collaborators,regarding the interaction between two D-branes,the open string pair production and its possible enhancement in Type Ⅱ superstring theories.Specifically,computed is the interaction amplitude between two D-branes,placed parallel at a separation,with each carrying a general worldvolume constant flux,and discussed are the amplitude properties,say,the repulsive or attractive nature of the interaction.When at least one of the D-branes carries an electric flux,the interaction amplitude can have an imaginary part,reflecting the instability of the underlying system via the open string pair production.The decay rate and the pair production rate are both computed.In addition,the enhancement of the latter is found when the added electric and magnetic fluxes are correlated in both magnitude and direction in a certain manner.In particular,when one of the branes is D3 and the other is D1,the corresponding pair production rate becomes large enough to be tested in an earthbound laboratory.Note that the pair production rate is related to the brane separation along the direction transverse to both branes,therefore,to the extra-dimensions with respect to the brane observer.So if the underlying string theory is relevant and the D3 can be taken as our own4-dimensional world,measuring,say,the electric current due to the pair production and comparing it against the added electric and magnetic fields to see if the measurements agree with the prediction of the computations.This can be used to verify the existence of extra-dimensions.Further,this provides also a potential new means to test the underlying string theory without the need of compactifying it to four dimensions.