49,951 research outputs found
On correspondences between toric singularities and (p,q) webs
We study four-dimensional N=1 gauge theories which arise from D3-brane probes of toric Calabi-Yau threefolds. There are some standing paradoxes in the literature regarding relations among (p,q)-webs, toric diagrams and various phases of the gauge theories, we resolve them by proposing and carefully distinguishing between two kinds of (p,q)-webs: toric and quiver (p,q)-webs. The former has a one to one correspondence with the toric diagram while the latter can correspond to multiple gauge theories. The key reason for this ambiguity is that a given quiver (p,q)-web can not capture non-chiral matter fields in the gauge theory. To support our claim we analyse families of theories emerging from partial resolution of Abelian orbifolds using the Inverse Algorithm of hep-th/0003085 as well as (p,q)-web techniques. We present complex inter-relations among these theories by Higgsing, blowups and brane splittings. We also point out subtleties involved in the ordering of legs in the (p,q) diagram
Professor Chen Ping Yang's early significant contributions to mathematical physics
In the 60's Professor Chen Ping Yang with Professor Chen Ning Yang published
several seminal papers on the study of Bethe's hypothesis for various problems
of physics. The works on the lattice gas model, critical behaviour in
liquid-gas transition, the one-dimensional (1D) Heisenberg spin chain, and the
thermodynamics of 1D delta-function interacting bosons are significantly
important and influential in the fields of mathematical physics and statistical
mechanics. In particular, the work on the 1D Heisenberg spin chain led to
subsequent developments in many problems using Bethe's hypothesis. The method
which Yang and Yang proposed to treat the thermodynamics of the 1D system of
bosons with a delta-function interaction leads to significant applications in a
wide range of problems in quantum statistical mechanics. The Yang and Yang
thermodynamics has found beautiful experimental verifications in recent years.Comment: 5 pages + 3 figure
Tunable Unidirectional Sound Propagation through a Sonic-Crystal-Based Acoustic Diode
Nonreciprocal wave propagation typically requires strong nonlinear materials to break time reversal symmetry. Here, we utilized a
sonic-crystal-based acoustic diode that had broken spatial inversion
symmetry and experimentally realized sound unidirectional transmission
in this acoustic diode. These novel phenomena are attributed to
different mode transitions as well as their associated different energy
conversion efficiencies among different diffraction orders at two sides
of the diode. This nonreciprocal sound transmission could be
systematically controlled by simply mechanically rotating the square
rods of the sonic crystal. Different from nonreciprocity due to the
nonlinear acoustic effect and broken time reversal symmetry, this new
model leads to a one-way effect with higher efficiency, broader
bandwidth, and much less power consumption, showing promising
applications in various sound devices
Two Particle States in a Box and the -Matrix in Multi-Channel Scattering
Using a quantum mechanical model, the exact energy eigenstates for
two-particle two-channel scattering are studied in a cubic box with periodic
boundary conditions.
A relation between the exact energy eigenvalue in the box and the two-channel
-matrix elements in the continuum is obtained. This result can be viewed as
a generalization of the well-known L\"uscher's formula which establishes a
similar relation in elastic scattering.Comment: 4 pages, typeset with ws-ijmpa.cls. Talk presented at International
Conference on QCD and Hadronic Physics, June 16-20, 2005, Beijing, China. One
reference adde
Parity-time electromagnetic diodes in a two-dimensional nonreciprocal photonic crystal
We propose a kind of electromagnetic (EM) diode based on a two-dimensional nonreciprocal gyrotropic photonic crystal. This
periodic microstructure has separately broken symmetries in both parity
(P) and time-reversal (T) but obeys parity-time (PT) symmetry. This
kind of diode could support bulk one-way propagating modes either for
group velocity or phase velocity with various types of negative and
positive refraction. This symmetry-broken system could be a platform to
realize abnormal photoelectronic devices, and it may be analogous to an
electron counterpart with one-way features
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