3,029 research outputs found
An anisotropic hybrid non-perturbative formulation for 4D N = 2 supersymmetric Yang-Mills theories
We provide a simple non-perturbative formulation for non-commutative
four-dimensional N = 2 supersymmetric Yang-Mills theories. The formulation is
constructed by a combination of deconstruction (orbifold projection), momentum
cut-off and matrix model techniques. We also propose a moduli fixing term that
preserves lattice supersymmetry on the deconstruction formulation. Although the
analogous formulation for four-dimensional N = 2 supersymmetric Yang-Mills
theories is proposed also in Nucl.Phys.B857(2012), our action is simpler and
better suited for computer simulations. Moreover, not only for the
non-commutative theories, our formulation has a potential to be a
non-perturbative tool also for the commutative four-dimensional N = 2
supersymmetric Yang-Mills theories.Comment: 32 pages, final version accepted in JHE
Absence of sign problem in two-dimensional N=(2,2) super Yang-Mills on lattice
We show that N=(2,2) SU(N) super Yang-Mills theory on lattice does not have
sign problem in the continuum limit, that is, under the phase-quenched
simulation phase of the determinant localizes to 1 and hence the phase-quench
approximation becomes exact. Among several formulations, we study models by
Cohen-Kaplan-Katz-Unsal (CKKU) and by Sugino. We confirm that the sign problem
is absent in both models and that they converge to the identical continuum
limit without fine tuning. We provide a simple explanation why previous works
by other authors, which claim an existence of the sign problem, do not capture
the continuum physics.Comment: 27 pages, 24 figures; v2: comments and references added; v3: figures
on U(1) mass independence and references added, to appear in JHE
Lattice formulation of two-dimensional N=(2,2) super Yang-Mills with SU(N) gauge group
We propose a lattice model for two-dimensional SU(N) N=(2,2) super Yang-Mills
model. We start from the CKKU model for this system, which is valid only for
U(N) gauge group. We give a reduction of U(1) part keeping a part of
supersymmetry. In order to suppress artifact vacua, we use an admissibility
condition.Comment: 16 pages, 3 figures; v2: typo crrected; v3: 18 pages, a version to
appear in JHE
Thermal phases of D1-branes on a circle from lattice super Yang-Mills
We report on the results of numerical simulations of 1+1 dimensional SU(N)
Yang-Mills theory with maximal supersymmetry at finite temperature and
compactified on a circle. For large N this system is thought to provide a dual
description of the decoupling limit of N coincident D1-branes on a circle. It
has been proposed that at large N there is a phase transition at strong
coupling related to the Gregory-Laflamme (GL) phase transition in the
holographic gravity dual. In a high temperature limit there was argued to be a
deconfinement transition associated to the spatial Polyakov loop, and it has
been proposed that this is the continuation of the strong coupling GL
transition. Investigating the theory on the lattice for SU(3) and SU(4) and
studying the time and space Polyakov loops we find evidence supporting this. In
particular at strong coupling we see the transition has the parametric
dependence on coupling predicted by gravity. We estimate the GL phase
transition temperature from the lattice data which, interestingly, is not yet
known directly in the gravity dual. Fine tuning in the lattice theory is
avoided by the use of a lattice action with exact supersymmetry.Comment: 21 pages, 8 figures. v2: References added, two figures were modified
for clarity. v3: Normalisation of lattice coupling corrected by factor of two
resulting in change of estimate for c_cri
Higher derivative corrections to black hole thermodynamics from supersymmetric matrix quantum mechanics
We perform a direct test of the gauge-gravity duality associated with the
system of N D0-branes in type IIA superstring theory at finite temperature.
Based on the fact that higher derivative corrections to the type IIA
supergravity action start at the order of \alpha'^3, we derive the internal
energy in expansion around infinite 't Hooft coupling up to the subleading term
with one unknown coefficient. The power of the subleading term is shown to be
nicely reproduced by the Monte Carlo data obtained nonperturbatively on the
gauge theory side at finite but large effective (dimensionless) 't Hooft
coupling constant. This suggests, in particular, that the open strings attached
to the D0-branes provide the microscopic origin of the black hole
thermodynamics of the dual geometry including \alpha' corrections. The
coefficient of the subleading term extracted from the fit to the Monte Carlo
data provides a prediction for the gravity side, which can be checked once the
complete form of the O(\alpha'^3) corrections to the supergravity action is
obtained.Comment: REVTeX4, 4 pages, 2 figures. Ver.2:intuitive derivation of the
subleading term adde
Cross-modal cue effects in motion processing
The everyday environment brings to our sensory systems competing inputs from different modalities. The ability to filter these multisensory inputs in order to identify and efficiently utilize useful spatial cues is necessary to detect and process the relevant information. In the present study, we investigate how feature-based attention affects the detection of motion across sensory modalities. We were interested to determine how subjects use intramodal, cross-modal auditory, and combined audiovisual motion cues to attend to specific visual motion signals. The results showed that in most cases, both the visual and the auditory cues enhance feature-based orienting to a transparent visual motion pattern presented among distractor motion patterns. Whereas previous studies have shown cross-modal effects of spatial attention, our results demonstrate a spread of cross-modal feature-based attention cues, which have been matched for the detection threshold of the visual target. These effects were very robust in comparisons of the effects of valid vs. invalid cues, as well as in comparisons between cued and uncued valid trials. The effect of intramodal visual, cross-modal auditory, and bimodal cues also increased as a function of motion-cue salience. Our results suggest that orienting to visual motion patterns among distracters can be facilitated not only by intramodal priors, but also by feature-based cross-modal information from the auditory system.First author draf
On Matrix Model Formulations of Noncommutative Yang-Mills Theories
We study stability of noncommutative spaces in matrix models and discuss the
continuum limit which leads to noncommutative Yang-Mills theories (NCYM). It
turns out that most of noncommutative spaces in bosonic models are unstable.
This indicates perturbative instability of fuzzy R^D pointed out by Van
Raamsdonk and Armoni et al. persists to nonperturbative level in these cases.
In this sense, these bosonic NCYM are not well-defined, or at least their
matrix model formulations studied in this paper do not work. We also show that
noncommutative backgrounds are stable in a supersymmetric matrix model deformed
by a cubic Myers term, though the deformation itself breaks supersymmetry.Comment: 24 pages, no figure, reference added, minor corrections, to be
published in PR
Numerical studies of the ABJM theory for arbitrary N at arbitrary coupling constant
We show that the ABJM theory, which is an N=6 superconformal U(N)*U(N)
Chern-Simons gauge theory, can be studied for arbitrary N at arbitrary coupling
constant by applying a simple Monte Carlo method to the matrix model that can
be derived from the theory by using the localization technique. This opens up
the possibility of probing the quantum aspects of M-theory and testing the
AdS_4/CFT_3 duality at the quantum level. Here we calculate the free energy,
and confirm the N^{3/2} scaling in the M-theory limit predicted from the
gravity side. We also find that our results nicely interpolate the analytical
formulae proposed previously in the M-theory and type IIA regimes. Furthermore,
we show that some results obtained by the Fermi gas approach can be clearly
understood from the constant map contribution obtained by the genus expansion.
The method can be easily generalized to the calculations of BPS operators and
to other theories that reduce to matrix models.Comment: 35 pages, 20 figures; reference added. The simulation code is
available upon request to [email protected]
Nonperturbative studies of supersymmetric matrix quantum mechanics with 4 and 8 supercharges at finite temperature
We investigate thermodynamic properties of one-dimensional U(N)
supersymmetric gauge theories with 4 and 8 supercharges in the planar large-N
limit by Monte Carlo calculations. Unlike the 16 supercharge case, the
threshold bound state with zero energy is widely believed not to exist in these
models. This led A.V. Smilga to conjecture that the internal energy decreases
exponentially at low temperature instead of decreasing with a power law. In the
16 supercharge case, the latter behavior was predicted from the dual black
0-brane geometry and confirmed recently by Monte Carlo calculations. Our
results for the models with 4 and 8 supercharges indeed support the exponential
behavior, revealing a qualitative difference from the 16 supercharge case.Comment: 16 pages, 7 figures, LaTeX2e, minor corrections in section 3, final
version accepted in JHE
- …