Effective Field Theories of the QCD Flux Tube: Can They Be Tested and What Can We Learn?

Il Prof. Marshall Baker (Dept. of Physics, University of Washington, Seattle, USA) terrà il seguente seminario:
Effective Field Theories of the QCD Flux Tube: Can They Be Tested and What Can We Learn?
(Aula multimediale 1° piano, giovedì 25 gennaio, ore 16:00)
ABSTRACT:
We consider effective field theories coupling magnetic SU(N) gauge potentials to magnetically charged Higgs scalar fields in the adjoint representation of SU(N). These fields interact via a Higgs potential which has a minimum at a non-vanishing value of the Higgs fields, such that in the confining vacuum the SU(N) symmetry is completely broken and all particles become massive. As a consequence, the chromoelectric field between a static quark and antiquark is distributed in tube-like structures whose width is determined by the mass M of the vector particle.

At large quark-antiquark separations R the heavy quark potential ? ⟶ ??, where string tension ? is the energy per unit length of the classical flux tube.
Long wavelength fluctuations of the axis of the flux tube give rise to an effective string theory yielding a heavy quark potential as an expansion in powers of 1/??(.

The leading order terms in this expansion are the linear potential ?? and the universal Luscher term – ?/12? arising from string fluctuations.
In this talk I focus on the features of effective field theory that do not depend on the details of the specific Lagrangian, and ask what we can test and what we can learn about this approach from lattice simulations of Yang-Mills theory.

We propose a new physical quantity characterizing the QCD flux tube, the total torque Τ(?) acting across any half plane through the flux tube passing through its axis. This characteristic distinguishes the QCD flux tube from flux tubes arising from other theories.

We obtain an expression to determine Τ(?) from lattice simulations.

A first step in testing and using effective field theory is to determine whether there is an interval of intermediate separations ? where the predictions of effective field theory at the classical level are not washed out by string fluctuations.

Making use of the results of recent lattice simulations, we find there is such an interval where the classical expression of the torque can be determined from lattice calculations.

Dr. Leonardo Cosmai, This email address is being protected from spambots. You need JavaScript enabled to view it., +39 0805443207