Andreas Athenodorou

Closed flux tubes and their string description in D=2+1 SU(N) gauge theories

We carry out lattice calculations of the spectrum of confining flux tubes that wind around a spatial torus of variable length l, in 2 + 1 dimensions. We compare the energies of the lowest ∼30 states to the free string Nambu-Goto model and to recent results on the universal properties of effective string actions. Our most useful calculations are in SU(6) at a small lattice spacing, which we check is very close to the N → ∞ continuum limit. We find that the energies, En(l), are remarkably close to the predictions of the free string Nambu-Goto model, even well below the critical length at which the expansion of the Nambu-Goto energy in powers of 1/l2 diverges and the series needs to be resummed. Our analysis of the ground state supports the universality of the O(1/l) and the O(1/l3) corrections to σl, and we find that the deviations from Nambu-Goto at small l prefer a leading correction that is O(1/l7), consistent with theoretical expectations. We find that the low-lying states that contain a single phonon excitation are also consistent with the leading O(1/l7) correction dominating down to the smallest values of l. By contrast our analysis of the other light excited states clearly shows that for these states the corrections at smaller l resum to a much smaller effective power. Finally, and in contrast to our recent calculations in D = 3 + 1, we find no evidence for the presence of any non-stringy states that could indicate the excitation of massive flux tube modes.

Infrared regime of SU(2) with one adjoint Dirac flavor

SU(2) gauge theory with one Dirac flavor in the adjoint representation is investigated on a lattice. Initial results for the gluonic and mesonic spectrum, static potential from Wilson and Polyakov loops, and the anomalous dimension of the fermionic condensate from the Dirac mode number are presented. The results found are not consistent with conventional confining behavior, pointing instead tentatively towards a theory lying within or very near the onset of the conformal window, with the anomalous dimension of the fermionic condensate in the range 0.9≲γ∗≲0.95. The implications of our work for building a viable theory of strongly interacting dynamics beyond the standard model are discussed.

Topological charge using cooling and the gradient flow

The equivalence of cooling to the gradient flow when the cooling step

On the zero crossing of the three-gluon vertex

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Neutron electric dipole moment using

and the continuous flow step of gradient flow

N_{f} =2+1+1

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twisted mass fermions

are matched is generalized to gauge actions that include rectangular terms. By expanding the link variables up to subleading terms in perturbation theory, we relate

SU(N ) gauge theories in 2+1 dimensions: glueball spectra and k-string tensions

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Closed flux tubes in D = 2 + 1 SU(N ) gauge theories: dynamics and effective string description

and

The spectrum of closed loops of fundamental flux in D=2+1 SU(N) gauge theories.

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