In physics

Physics

Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

, a quiver diagram is a graph representing the matter

Matter

Matter is a general term for the substance of which all physical objects consist. Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume...

 content of a gauge theory

Gauge theory

In physics, gauge invariance is the property of a field theory in which different configurations of the underlying fundamental but unobservable fields result in identical observable quantities. A theory with such a property is called a gauge theory...

 that describes D-branes on orbifold

Orbifold

In the mathematical disciplines of topology, geometry, and geometric group theory, an orbifold is a generalization of a manifold...

s.

Each node of the graph corresponds to a factor U(N)

Unitary group

In mathematics, the unitary group of degree n, denoted U, is the group of n×n unitary matrices, with the group operation that of matrix multiplication. The unitary group is a subgroup of the general linear group GL...

 of the gauge group, and each link represents a field in the bifundamental representation

Bifundamental representation

In mathematics and theoretical physics, a bifundamental representation is a representation obtained as a tensor product of two fundamental or antifundamental representations....

.

The relevance of quiver diagrams for string theory

String theory

String theory is an active research framework in particle physics that attempts to reconcile quantum mechanics and general relativity. It is a contender for a theory of everything , a manner of describing the known fundamental forces and matter in a mathematically complete system...

 was pointed out and studied by Michael Douglas

Michael R. Douglas

Michael R. Douglas is an American theoretical physicist and professor currently at Stony Brook University.Michael R. Douglas was born in Baton Rouge, Louisiana, the son of Nancy and Ronald G. Douglas, a mathematician specializing in operator algebras. He received his bachelor's degree in physics...

 and Greg Moore.

While string theorists use the words quiver diagram, many of their colleagues in particle physics

Particle physics

Particle physics is a branch of physics that studies the existence and interactions of particles that are the constituents of what is usually referred to as matter or radiation. In current understanding, particles are excitations of quantum fields and interact following their dynamics...

call these diagrams mooses.