105 research outputs found
Non-Abelian Moduli on Domain Walls
We study a simple model supporting domain walls which possess two
orientational moduli in addition to the conventional translational modulus.
This model is conceptually close to Witten's cosmic strings. We observe an
sigma model on the wall world volume in the low-energy limit. We solve
(numerically) classical static equations of motion and find the wall profile
functions and the value of the coupling of the model in terms of the
bulk parameters. In the second part a term describing a spin-orbit interaction
in the bulk is added, which gives rise to an entanglement between rotational
and translational moduli. The corresponding extra term in the low-energy
Lagrangian is calculated.Comment: 11 pages, 4 figure
A note on C-Parity Conservation and the Validity of Orientifold Planar Equivalence
We analyze the possibility of a spontaneous breaking of C-invariance in gauge
theories with fermions in vector-like - but otherwise generic - representations
of the gauge group. QCD, supersymmetric Yang-Mills theory, and orientifold
field theories, all belong to this class. We argue that charge conjugation is
not spontaneously broken as long as Lorentz invariance is maintained.
Uniqueness of the vacuum state in pure Yang-Mills theory (without fermions) and
convergence of the expansion in fermion loops are key ingredients. The fact
that C-invariance is conserved has an interesting application to our proof of
planar equivalence between supersymmetric Yang-Mills theory and orientifold
field theory on R4, since it allows the use of charge conjugation to connect
the large-N limit of Wilson loops in different representations.Comment: 9 pages, LaTex. v2: minor changes, accepted to Phys.Lett.
BPS Spectrum of Supersymmetric CP(N-1) Theory with Z_N Twisted Masses
We revisit the BPS spectrum of the supersymmetric CP(N-1) two-dimensional
model with Z_N-symmetric twisted masses m_l (l=0,1, ..., N-1). A related issue
we address is that of the curves of marginal stability (CMS) in this theory.
Previous analyses were incomplete. We close the gap by exploiting a number of
consistency conditions. In particular, we amend the Dorey formula for the BPS
spectrum. Our analysis is based on the exact Veneziano--Yankielowicz-type
superpotential and on the strong-coupling spectrum of the theory found from the
mirror representation at small masses, |m_l| << \Lambda . We show that at weak
coupling the spectrum, with necessity, must include N-1 BPS towers of states,
instead of just one, as was thought before. Only one of the towers is seen in
the quasiclassical limit. We find the corresponding CMS for these towers, and
argue that in the large-N limit they become circles, filling out a band on the
plane of a single mass parameter of the model at hand. Inside the CMS, N-1
towers collapse into N stable states.Comment: 40 pages, 14 figures; minor correction
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