43,790 research outputs found
Quantum parameter space in super Yang-Mills, II
In [1] (hep-th/0211069), the author has discussed the quantum parameter space
of the N=1 super Yang-Mills theory with one adjoint Higgs field Phi, tree-level
superpotential W_tree = m (Phi^2)/2 + g (Phi^3)/3$, and gauge group U(Nc). In
particular, full details were worked out for U(2) and U(3). By discussing
higher rank gauge groups like U(4), for which the classical parameter space has
a large number of disconnected components, we show that the phenomena discussed
in [1] are generic. It turns out that the quantum space is connected. The
classical components are related in the quantum theory either through standard
singularities with massless monopoles or by branch cuts without going through
any singularity. The branching points associated with the branch cuts
correspond to new strong coupling singularities, which are not associated with
vanishing cycles in the geometry, and at which glueballs can become massless.
The transitions discussed recently by Cachazo, Seiberg and Witten are special
instances of those phenomena.Comment: 12 pages including 2 large figure
Slalom in complex time: emergence of low-energy structures in tunnel ionization via complex time contours
The ionization of atoms by strong, low-frequency fields can generally be
described well by assuming that the photoelectron is, after the ionization
step, completely at the mercy of the laser field. However, certain phenomena,
like the recent discovery of low-energy structures in the long-wavelength
regime, require the inclusion of the Coulomb interaction with the ion once the
electron is in the continuum. We explore the first-principles inclusion of this
interaction, known as analytical R-matrix theory, and its consequences on the
corresponding quantum orbits. We show that the trajectory must have an
imaginary component, and that this causes branch cuts in the complex time plane
when the real trajectory revisits the neighbourhood of the ionic core. We
provide a framework for consistently navigating these branch cuts based on
closest-approach times, which satisfy the equation in the complex plane. We explore the geometry of these roots
and describe the geometrical structures underlying the emergence of LES in both
the classical and quantum domains.Comment: Supplementary information at
http://episanty.github.io/Slalom-in-complex-time
Geometrically Induced Phase Transitions at Large N
Utilizing the large N dual description of a metastable system of branes and
anti-branes wrapping rigid homologous S^2's in a non-compact Calabi-Yau
threefold, we study phase transitions induced by changing the positions of the
S^2's. At leading order in 1/N the effective potential for this system is
computed by the planar limit of an auxiliary matrix model. Beginning at the two
loop correction, the degenerate vacuum energy density of the discrete confining
vacua split, and a potential is generated for the axion. Changing the relative
positions of the S^2's causes discrete jumps in the energetically preferred
confining vacuum and can also obstruct direct brane/anti-brane annihilation
processes. The branes must hop to nearby S^2's before annihilating, thus
significantly increasing the lifetime of the corresponding non-supersymmetric
vacua. We also speculate that misaligned metastable glueball phases may
generate a repulsive inter-brane force which stabilizes the radial mode present
in compact Calabi-Yau threefolds.Comment: 47 pages, 7 figure
Phase Structure of a Brane/Anti-Brane System at Large N
We further analyze a class of recently studied metastable string vacua
obtained by wrapping D5-branes and anti-D5-branes over rigid homologous S^2's
of a non-compact Calabi-Yau threefold. The large N dual description is
characterized by a potential for the glueball fields which is determined by an
auxiliary matrix model. The higher order corrections to this potential produce
a suprisingly rich phase structure. In particular, at sufficiently large 't
Hooft coupling the metastable vacua present at weak coupling cease to exist.
This instability can already be seen by an open string two loop contribution to
the glueball potential. The glueball potential also lifts some of the
degeneracy in the vacua characterized by the phases of the glueball fields.
This generates an exactly computable non-vanishing axion potential at large N.Comment: v3: 55 pages, 11 figures, typos correcte
On Geometry and Matrix Models
We point out two extensions of the relation between matrix models,
topological strings and N=1 supersymmetric gauge theories. First, we note that
by considering double scaling limits of unitary matrix models one can obtain
large N duals of the local Calabi-Yau geometries that engineer N=2 gauge
theories. In particular, a double scaling limit of the Gross-Witten
one-plaquette lattice model gives the SU(2) Seiberg-Witten solution, including
its induced gravitational corrections. Secondly, we point out that the
effective superpotential terms for N=1 ADE quiver gauge theories is similarly
computed by large multi-matrix models, that have been considered in the context
of ADE minimal models on random surfaces. The associated spectral curves are
multiple branched covers obtained as Virasoro and W-constraints of the
partition function.Comment: 24 page
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