Holographic Quantum Chromodynamics research - Qian Li, Ph.D
In order to study the strong coupling behavior of quantum chromodynamics in the low energy region, we experimentally collide leptons with hadrons, hadrons with hadrons, and nuclei with nuclei at high speed. The initial collision produced hadron jets and bifelton pairs of heavy taste quarks. Some molecules inside the nucleus are released by high-energy collisions, forming a dense material, inheriting strong interactions and presenting elliptical flows. Thermalized quark gluon plasma. Finally, it expands and cools. In the local thermal equilibrium region, hadrons with increasingly distant interactions are formed and can be ignored, which are received by the detector. In recent years, a variety of interesting phenomena, such as P/CP parity, chiral magnetic effect (CME), chiral vortex effect (CVE) and anomalous coefficient, have appeared in large hadron physics experiments (such as RHIC and LHC), which have become the emerging theoretical focus.
It is well known that quantum chromodynamics is not suitable for perturbation in low energy regions. T 'Hooft first proposed the large N limit to study, and used the color freedom of QCD N as the expansion parameter. When N tends to infinity, the theory of strong phase interaction becomes the classical theory of weak coupling. SU(N) theory is regarded as the theory of N overlapping D branes. The feynman diagram of the perturbation expansion of SU(N) theory changes from the circle diagram on the plane to the topological expansion of the closed Riemannian surface, which corresponds to the gravitational perturbation expansion of D-film in higher dimensional space-time. As an extension of this AdS/CFT duality, gauge/gravitational duality studies the nonperturbative properties of quantum chromodynamics.
In the large N limit, the quark with SU(N) basis represents the index, which is represented by a single line, and the gluon with adjoint represents the index. Because there are generative elements, it can be regarded as the positive and negative basic representation of direct product decomposition.
Perturbation expansion of any correlation function
Where G is deficient. The circle chart correction is depressed by large N.
There are different low energy efficient theories for different parameter regions of the same physical system. Take D3 membrane as an example :(1) at that time, that is, far away from D3 membrane
If n coincide D branes, the open chord endpoints have U(n) gauge symmetry.
Quarks have flavor and color degrees of freedom. D4 represents color film and D8 represents taste film. The low energy dynamics of D films can be described by the gauge field excited on them. D branes will have open string excitation. One end of the string is in the D4 color film, one end is in the D8 taste film, and the resulting canonical field degree of freedom is exactly
Because there is no direction perpendicular to both D4 and D8 branes, dual field theory quarks are massless. The background of supergravity needs to be in a certain direction of D4 film, where the fourth dimension is selected for compactification. D4 occupies the first 4 dimensions and obtains antiperiodic boundary conditions for Fermions on compact dimensions. So supersymmetry is completely broken. Low energy supergravity can be described in the near-horizon region by classical gravity theory in BULK or gauge theory on membrane.
D0-d4 solution of Type IIA supergravity in Einstein framework,