834 research outputs found
On the linear increase of the flux tube thickness near the deconfinement transition
We study the flux tube thickness of a generic Lattice Gauge Theory near the
deconfining phase transition. It is well known that the effective string model
predicts a logarithmic increase of the flux tube thickness as a function of the
interquark distance for any confining LGT at zero temperature. It is perhaps
less known that this same model predicts a linear increase in the vicinity of
the deconfinement transition. We present a precise derivation of this result
and compare it with a set of high precision simulations in the case of the 3d
gauge Ising model.Comment: 20 pages, 4 figures, minor changes. Accepted for publication in JHE
String effects in SU(2) lattice gauge theory
We discuss the effective string picture for the confining regime of lattice
gauge theories at zero and finite temperature. We present results of extensive
Monte Carlo simulations - performed with the Luscher and Weisz algorithm - for
SU(2) Yang-Mills theory in 2+1 dimensions. We also address the issue of "string
universality" by comparing our results with those obtained in other lattice
gauge theories.Comment: 3 pages, 2 figures, Lattice2003(topology
Static quark potential and effective string corrections in the (2+1)-d SU(2) Yang-Mills theory
We report on a very accurate measurement of the static quark potential in
SU(2) Yang-Mills theory in (2+1) dimensions in order to study the corrections
to the linear behaviour. We perform numerical simulations at zero and finite
temperature comparing our results with the corrections given by the effective
string picture in these two regimes. We also check for universal features
discussing our results together with those recently published for the (2+1)-d
Z(2) and SU(3) pure gauge theories.Comment: 29 pages, 6 figure
Short distance behaviour of the effective string
We study the Polyakov loop correlator in the (2+1) dimensional Z_2 gauge
model. An algorithm that we have presented recently, allows us to reach high
precision results for a large range of distances and temperatures, giving us
the opportunity to test predictions of the effective Nambu-Goto string model.
Here we focus on the regime of low temperatures and small distances. In
contrast to the high temperature, large distance regime, we find that our
numerical results are not well described by the two loop-prediction of the
Nambu-Goto model. In addition we compare our data with those for the SU(2) and
SU(3) gauge models in (2+1) dimensions obtained by other authors. We generalize
the result of L\"uscher and Weisz for a boundary term in the interquark
potential to the finite temperature case.Comment: 38 pages, 7 figures, version accepted for publication in JHE
Universal behaviour of interfaces in 2d and dimensional reduction of Nambu-Goto strings
We propose a simple effective model for the description of interfaces in 2d
statistical models, based on the first-order treatment of an action
corresponding to the length of the interface. The universal prediction of this
model for the interface free energy agrees with the result of an exact
calculation in the case of the 2d Ising model. This model appears as a
dimensional reduction of the Nambu-Goto stringy description of interfaces in
3d, i.e., of the capillary wave model.Comment: 14 pages, 1 figur
Flux tube delocalization at the deconfinement point
We study the behaviour of the flux tube thickness in the vicinity of the
deconfinement transition. We show, using effective string methods, that in this
regime the square width increases linearly and not logarithmically with the
interquark distance. The amplitude of this linear growth is an increasing
function of the temperature and diverges as the deconfinement transition is
approached from below. These predictions are in good agreement with a set of
simulations performed in the 3d gauge Ising model.Comment: 16 pages, 1 figure. Revised version, with an improved discussion of
the dimensional reduction approach. Accepted for publication in JHE
The Lorentz-invariant boundary action of the confining string and its universal contribution to the inter-quark potential
We study the boundary contribution to the low energy effective action of the
open string describing the confining flux tube in gauge theories. The form of
the boundary terms is strongly constrained by the requirement of Lorentz
symmetry, which is spontaneously broken by the formation of a long confining
flux tube in the vacuum. Writing the boundary action as an expansion in the
derivatives of the Nambu-Goldstone modes describing the transverse fluctuations
of the string, we single out and put in a closed form the first few Lorentz
invariant boundary terms. We also evaluate the leading deviation from the
Nambu-Goto string produced by the boundary action on the vacuum expectation
value of the Wilson loop and we test this prediction in the 3d Ising gauge
model. Our simulation attains a level of precision which is sufficient to test
the contribution of this term.Comment: 17 pages, 5 figures, LateX 2e. V2: Final version published on JHEP.
Fixed typos in eq.s 2.2, 2.3, 3.7, 3.8, A.4. Extended explanation of the
procedures used in sec 2 to determine the possible boundary terms up to field
redefinitions and of the procedure used in sec 4 to take the continuum limit.
V3: typos corrected in eq.s (4.3) (4.5) and (4.6), acknowledgements adde
A new universality class describing the insulating regime of disordered wires with strong spin-orbit scattering
We discuss the distribution of transmission eigenvalues in the strongly
localized regime in the presence of both a magnetic field and spin--orbit
scattering. We show that, under suitable conditions, this distribution can be
described by a new universality class labelled not only by the index
but also by a new index . This result is obtained by mapping the problem
into that of a suitable Calogero-Sutherland model.Comment: 4 pages, Revte
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