Numeric Energy Loss Of Jet In The Stongly Coupled Quark Gluon Plasma

Gauge/Gravity duality or AdS/CFT duality is a hot spot in theoretical physics re-searching in recent years. By combining gravity with the gauge field theory, we can solve the gauge field theory problem from gravity side. Some tricky strong coupled field theory problem can be solved due to the strong-weak duality in AdS/CFT. AdS/QCD means researching QCD problem by AdS/CFT duality. In QCD, jet in quark gluon plasma is a very important topic. In AdS/QCD, given that N= 4 SYM shares many common features with QCD but is more easy, N= 4 SYM is studied instead of QCD. In the dual string theory, a dual string whose end points represent quark is the duality of the jet. By computing the dual string itself or the dilaton or metric field perturbance on the AdS boundary caused by the string, we can learn the information of the dual jet such as energy loss rate. We calculate the perturbance of dilaton field from a falling string in AdS-Schwarzschild space time. We choose the part of the string which is above the thermal holographic coordinate following R. Morad and W. A. Horowitz.The thermal holographic coordinate is dual to a special energy scalar under which the jet can not be distinguished from the plasma medium, so we argue that the string below the thermal holographic coordinate won't be the jet. In this paper, the perturbance of the dilaton field on the AdS-Schwarzschild boundary due to the part above the thermal holographic coordinate of the string is numerically calculated. After numerical calculation,our the en-ergy loss rate is different from the results before:the energy of jet decay very fast in early stage. In the works before,the energy lost rate can be described as Bragge Peak(when the heavy ion enters into the electric plasma,energy of ion barely decay in the early stage, after some time a very fast energy loss appears, which is called Bragge peak). Considering that in our case, the light particle is shot into the strong coupled plasma(quark-gluon plasma), not the heavy particle into the weak coupled plasma(electric plasma), we deem that our result reflect the difference between the light/heavy particle and the weak/strong coupled plasma.