313 research outputs found
Hidden Modulus in the Extended Veneziano-Yankielowicz Theory
The issue of domain walls in the recently extended Veneziano-Yankielowicz
theory is investigated and we show that they have an interesting substructure.
We also demonstrate the presence of a noncompact modulus. The associated family
of degenerate solutions is physically due to the presence of a valley of vacua
in the enlarged space of fields. This is a feature of the extended
Veneziano-Yankielowicz theory. Unfortunately the above properties do not match
the ones expected for the domain walls of N=1 super Yang-Mills.Comment: LaTeX, 13 pages and 5 figs, v3 misprints correcte
Heat kernel for Newton-Cartan trace anomalies
We compute the leading part of the trace anomaly for a free non-relativistic
scalar in 2+1 dimensions coupled to a background Newton-Cartan metric. The
anomaly is proportional to 1/m, where m is the mass of the scalar. We comment
on the implications of a conjectured a-theorem for non-relativistic theories
with boost invariance.Comment: 18 page
Monopoles Can be Confined by 0, 1 or 2 Vortices
There are three types of monopole in gauge theories with fundamental matter
and N=2 supersymmetry broken by a superpotential. There are unconfined
0-monopoles and also 1 and 2-monopoles confined respectively by one or two
vortices transforming under distinct components of the unbroken gauge group. If
a Fayet-Iliopoulos term is added then there are only 2-monopoles. Monopoles
transform in the bifundamental representation of two components of the unbroken
gauge symmetry, and if two monopoles share a component they may form a
boundstate. Selection rules for this process are found, for example vortex
number is preserved modulo 2. We find the tensions of the vortices, which are
in general distinct, and also the conditions under which vortices are mutually
BPS. Results are derived in field theory and also in MQCD, and in quiver
theories a T-dual picture may be used in which monopoles are classified by
quiver diagrams with two colors of vertices.Comment: 46 pages, 13 figures, V2: Comment on non-BPS correction added; 1
figure adde
The holographic non-abelian vortex
We study a fully back-reacted non-abelian vortex solution in an extension of
the holographic superconductor setup. The thermodynamic properties of the
vortex are computed. We show that, in some regime of parameters, the
non-abelian vortex solution has a lower free energy than a competing abelian
vortex solution. The solution is dual to a finite-temperature perturbed
conformal field theory with a topological defect, on which operators related to
the Goldstone modes of a spontaneously broken symmetry are localized. We
compute numerically the retarded Green function of these operators and we find,
in the classical approximation in the bulk, a gapless
excitation on the vortex world line.Comment: 28 pages, 7 figure
Trace anomaly for non-relativistic fermions
We study the coupling of a 2+1 dimensional non-relativistic spin 1/2 fermion
to a curved Newton-Cartan geometry, using null reduction from an
extra-dimensional relativistic Dirac action in curved spacetime. We analyze
Weyl invariance in detail: we show that at the classical level it is preserved
in an arbitrary curved background, whereas at the quantum level it is broken by
anomalies. We compute the trace anomaly using the Heat Kernel method and we
show that the anomaly coefficients a, c are proportional to the relativistic
ones for a Dirac fermion in 3+1 dimensions. As for the previously studied
scalar case, these coefficents are proportional to 1/m, where m is the
non-relativistic mass of the particle.Comment: 23 page
On Newton-Cartan trace anomalies
We classify the trace anomaly for parity-invariant non-relativistic
Schr\"odinger theories in 2+1 dimensions coupled to background Newton-Cartan
gravity. The general anomaly structure looks very different from the one in the
z=2 Lifshitz theories. The type A content of the anomaly is remarkably
identical to that of the relativistic 3+1 dimensional case, suggesting the
conjecture that an a-theorem should exist also in the Newton-Cartan context.
Erratum: due to an overcounting of the number of linearly-independent terms
in the basis, the type A anomaly disappears if Frobenius condition is imposed.
See appended erratum for details. This crucial mistake was pointed out to us in
arXiv:1601.06795.Comment: 16 pages, V2:few equations corrected (final results unchanged),
references added, typos, V3: erratum include
Nonrelativistic trace and diffeomorphism anomalies in particle number background
Using the heat kernel method, we compute nonrelativistic trace anomalies for
Schr\"odinger theories in flat spacetime, with a generic background gauge field
for the particle number symmetry, both for a free scalar and a free fermion.
The result is genuinely nonrelativistic, and it has no counterpart in the
relativistic case. Contrary to the naive expectations, the anomaly is not
gauge-invariant; this is similar to the non-gauge covariance of the non-abelian
relativistic anomaly. We also show that, in the same background, the
gravitational anomaly for a nonrelativistic scalar vanishes.Comment: 20 pages; V2 minor changes also in title, typo
Higher Winding Strings and Confined Monopoles in N=2 SQCD
We consider composite string solutions in N=2 SQCD with the gauge group U(N),
the Fayet--Iliopoulos term \xi \neq 0 and N (s)quark flavors. These bulk
theories support non-Abelian strings and confined monopoles identified with
kinks in the two-dimensional world-sheet theory. Similar and more complicated
kinks (corresponding to composite confined monopoles) must exist in the
world-sheet theories on composite strings. In a bid to detect them we analyze
the Hanany--Tong (HT) model, focusing on a particular example of N=2. Unequal
quark mass terms in the bulk theory result in the twisted masses in the N=(2,2)
HT model. For spatially coinciding 2-strings, we find three distinct minima of
potential energy, corresponding to three different 2-strings. Then we find
BPS-saturated kinks interpolating between each pair of vacua. Two kinks can be
called elementary. They emanate one unit of the magnetic flux and have the same
mass as the conventional 't Hooft--Polyakov monopole on the Coulomb branch of
the bulk theory (\xi =0). The third kink represents a composite bimonopole,
with twice the minimal magnetic flux. Its mass is twice the mass of the
elementary confined monopole. We find instantons in the HT model, and discuss
quantum effects in composite strings at strong coupling. In addition, we study
the renormalization group flow in this model.Comment: 41 pages, 11 figure
- …