Glauber gluons, i.e. soft gluons with momentum scaling dominated by the transverse component, are the most challenging aspect in the derivations of factorization theorems, in particular at hadron colliders. For a number of different observables, it has been explicitly demonstrated that the exchanges of Glauber gluons between different collinear sectors violate factorization. Examples include event-shape variables and total transverse momentum in production of colored particles.
For a number of different observables, it has been explicitly demonstrated that factorization is violated due to the exchange of soft gluons with momentum scaling dominated by the transverse component. These Glauber gluons constitute the most challenging aspect of the derivations of factorization theorems, separating the long- and short-distance physics at colliders.
There has been a number of recent developments and breakthroughs in the theoretical treatment of factorization violating gluon exchanges. Glauber gluons have been included in the effective theory framework of Soft Collinear Effective Theory. In full QCD the Glauber momentum regions have been isolated and treated explicitly. A connection between multiparton interactions and factorization violating gluons has been established. Further, in non-global observables the Glauber gluons produce super-leading logarithms, and at amplitude level they can violate collinear factorization.
The Scientific Program brings together the leading experts of the different approaches to identify, calculate and when possible cure the factorization violating effects.