23,217 research outputs found
Maximally Non-Abelian Vortices from Self-dual Yang--Mills Fields
A particular dimensional reduction of SU(2N) Yang--Mills theory on , with a Riemann surface, yields an
gauge theory on , with a matrix Higgs field. The SU(2N) self-dual
Yang--Mills equations reduce to Bogomolny equations for vortices on .
These equations are formally integrable if is the hyperbolic plane,
and we present a subclass of solutions.Comment: 11 page
More on a holographic dual of QCD
We investigate the interactions among the pion, vector mesons and external
gauge fields in the holographic dual of massless QCD proposed in a previous
paper, hep-th/0412141, on the basis of probe D8-branes embedded in a D4-brane
background in type IIA string theory. We obtain the coupling constants by
performing both analytic and numerical calculations, and compare them with
experimental data. It is found that the vector meson dominance in the pion form
factor as well as in the Wess-Zumino-Witten term holds in an intriguing manner.
We also study the \omega to \pi\gamma and \omega to 3\pi decay amplitudes. It
is shown that the interactions relevant to these decay amplitudes have the same
structure as that proposed by Fujiwara et al. Various relations among the
masses and the coupling constants of an infinite tower of mesons are derived.
These relations play crucial roles in the analysis. We find that most of the
results are consistent with experiments.Comment: Latex2e, 40 pages, 6 figures, v2: references added, typos corrected,
v3: PTP-style, typos corrected, v4: minor correction
T-duality of the Green-Schwarz superstring
We study T-duality in the Green-Schwarz formalism to all orders in superspace
coordinates. We find two analogs of Buscher rules for the supervielbein and
clarify their meaning from the superstring point of view. The transformation
rules for the dilaton, spin 1/2 fermions and Ramond-Ramond superfields are also
derived.Comment: 21 pages, late
Triangle singularities in and
We study the appearance of structures in the decay of the into and final states by forming
invariant mass distributions of and pairs,
respectively. The structure in the distribution is associated to the
kinematical triangle singularity that appears when the () decay process is followed by the decay
of the into and the subsequent rescattering of the () pair forming the ()
resonance. We find this type of non-resonant peaks at 2850 MeV in the invariant
mass of pairs from decays and
around 3000 MeV in the invariant mass of pairs from decays. By employing the measured branching ratios of
the and decays, we
predict the branching ratios for the processes into and , in the vicinity of the
triangle singularity peak, to be about and ,
respectively. The observation of this reaction would also give extra support to
the molecular picture of the and .Comment: 18 pages, 15 figures, accepted version for publication in Eur. Phys.
J.
Quantum Monte Carlo study for multiorbital systems with preserved spin and orbital rotational symmetries
We propose to combine the Trotter decomposition and a series expansion of the
partition function for Hund's exchange coupling in a quantum Monte Carlo (QMC)
algorithm for multiorbital systems that preserves spin and orbital rotational
symmetries. This enables us to treat the Hund's (spin-flip and pair-hopping)
terms, which is difficult in the conventional QMC method. To demonstrate this,
we first apply the algorithm to study ferromagnetism in the two-orbital Hubbard
model within the dynamical mean-field theory (DMFT). The result reveals that
the preservation of the SU(2) symmetry in Hund's exchange is important, where
the Curie temperature is grossly overestimated when the symmetry is degraded,
as is often done, to Ising (Z). We then calculate the spectral
functions of SrRuO by a three-band DMFT calculation with tight-binding
parameters taken from the local density approximation with proper rotational
symmetry.Comment: 9 pages, 9 figures. Typos corrected, some comments and references
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