205 research outputs found
Spinorial flux tubes in SO(N) gauge theories in 2+1 dimensions
We investigate whether one can observe in SO(3) and SO(4) (lattice) gauge
theories the presence of spinorial flux tubes, i.e. ones that correspond to the
fundamental representation of SU(2); and similarly for SO(6) and SU(4). We do
so by calculating the finite volume dependence of the JP=2+ glueball in 2+1
dimensions, using lattice simulations. We show how this provides strong
evidence that these SO(N) gauge theories contain states that are composed of
pairs of (conjugate) winding spinorial flux tubes, i.e. ones that are in the
(anti)fundamental of the corresponding SU(N') gauge theories. Moreover, these
two flux tubes can be arbitrarily far apart. This is so despite the fact that
the fields that are available in the SO(N) lattice field theories do not appear
to allow us to construct operators that project onto single spinorial flux
tubes.Comment: 23 pages, 8 figures, reference to recent relevant paper, version to
be submitted to journa
Confinement and the effective string theory in SU(N->oo) : a lattice study
We calculate in the SU(6) gauge theory the mass of the lightest flux loop
that winds around a spatial torus, as a function of the torus size, taking care
to achieve control of the main systematic errors. For comparison we perform a
similar calculation in SU(4). We demonstrate approximate linear confinement and
show that the leading correction is consistent with what one expects if the
flux tube behaves like a simple bosonic string at long distances. We obtain
similar but less accurate results for stable (k-)strings in higher
representations. We find some evidence that for k>1 the length scale at which
the bosonic string correction becomes dominant increases as N increases. We
perform all these calculations not just for long strings, up to about 2.5`fm'
in length, but also for shorter strings, down to the minimum length, lc = 1/Tc,
where Tc is the deconfining temperature. We find that the mass of the
ground-state string, at all length scales, is not very far from the simple
Nambu-Goto string theory prediction, and that the fit improves as N increases
from N=4 to N=6. We estimate the mass of the first excited string and find that
it also follows the Nambu-Goto prediction, albeit more qualitatively. We
comment upon the significance of these results for the string description of
SU(N) gauge theories in the limit of infinite N.Comment: 21 pages, 5 figure
On the spectrum and string tension of U(1) lattice gauge theory in 2+1 dimensions
We calculate the low-lying spectra of glueballs and confining flux tubes in
the U(1) lattice gauge theory in 2+1 dimensions. We see that up to modest
lattice spacing corrections, the glueball states are consistent with being
multiparticle states composed of non-interacting massive JPC=0-- particles. We
observe that the ag^2 -> 0 limit is, as expected, unconventional, and follows
the well-known saddle-point analysis of Polyakov to a good approximation. The
spectrum of closed (winding) flux tubes exhibits the presence of a massive
world-sheet excitation whose mass is consistent with that of the bulk screening
mass. These U(1) calculations are intended to complement existing lattice
calculations of the properties of SU(N) and SO(N) gauge theories in D=2+1.Comment: 39 pages; 15 figures. Extra discussion, calculation, figures and
reference
Closed flux tubes in D=2+1 SU(N) gauge theories: dynamics and effective string description
We extend our earlier calculations of the spectrum of closed flux tubes in
SU(N) gauge theories in 2+1 dimensions, with a focus on questions raised by
recent theoretical progress on the effective string action of long flux tubes
and the world-sheet action for flux tubes of moderate lengths. Our new
calculations in SU(4) and SU(8) provide evidence that the leading O(1/l^gamma)
non-universal correction to the flux tube ground state energy does indeed have
a power gamma greater than or equal to 7. We perform a study in SU(2), where we
can traverse the length at which the Nambu-Goto ground state becomes tachyonic,
to obtain an all-N view of the spectrum. Our comparison of the k=2 flux tube
excitation energies in SU(4) and SU(6) suggests that the massive world sheet
excitation associated with the k=2 binding has a scale that knows about the
group and hence the theory in the bulk, and we comment on the potential
implications of world sheet massive modes for the bulk spectrum. We provide a
quantitative analysis of the surprising (near-)orthogonality of flux tubes
carrying flux in different SU(N) representations, which implies that their
screening by gluons is highly suppressed even at small N.Comment: 72 pages, including 42 figure
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