Search for higher dimensions through their gravitational effects in high energy collisions

We consider the use of a microwave parametric converter for the direct detection of gravitational effects at the LHC. Because of the extra dimensions the strength of the gravitational interaction in the bulk grows at high energies. This leads to possibly detectable signals. The existence of additional dimensions has been widely discussed in connection with string theory [1]. It has been proposed that the extra dimensions would modify the gravitational interaction so that it becomes strong at an energy scale well below the Planck mass, possibly as low as a few TeV. Experimental signatures at the Large Hadron Collider (LHC) have been identified [2,3]. Here we speculate on the direct detection of the gravitational effects in high energy particle collisions by using an electromagnetic detector which couples directly to deformations of the space-time (3+1) metric [4]. We consider two cases and in both instances we exploit the periodic nature of the signal which is related to the collision frequency at the LHC, f = 31.6 MHz. In the first case we examine the deformation of the metric due to the passage of the particle bunch in the vicinity of the detector. This is a kinematic rather than a dynamic effect. In the second case we assume that during the collision, gravitational radiation is emitted into the higher dimensions (the bulk). We argue that as a consequence an “evanescent” gravitational wave is generated on the brane, and it is this disturbance of the metric that is detected [5] 1. Passage of a relativistic particle When a fast-moving particle of mass m passes by a stationary observer the metric is deformed and at closest approach, at a distance b, is