A crowd of hundreds stopped traffic on city streets surrounding the Yale University campus Monday in a march to show solidarity with minority students who say they are barred from full participation at the Ivy League school. Winding their way past the university’s four cultural centers — and the Yale chapter of Sigma Alpha Epsilon, where brothers have been accused of turning black women away from a party last weekend — students displayed signs urging the university to support women of color, faculty of color and ethnic studies. One sign read: “Your move Yale.”