1,234 research outputs found
Quantum-Squeezing-Induced Point-Gap Topology and Skin Effect
We theoretically predict the squeezing-induced point-gap topology together
with a {\it symmetry-protected skin effect} in a one-dimensional
(1D) quadratic-bosonic system (QBS). Protected by a time-reversal symmetry,
such a topology is associated with a novel invariant (similar to
quantum spin-Hall insulators), which is fully capable of characterizing the
occurrence of skin effect. Focusing on zero energy, the
parameter regime of this skin effect in the phase diagram just corresponds to a
{\it real-gap and point-gap coexisted topological phase}. Moreover, this phase
associated with the {\it symmetry-protected skin effect} is
experimentally observable by detecting the steady-state power spectral density.
Our work is of fundamental interest in enriching non-Bloch topological physics
by introducing quantum squeezing, and has potential applications for the
engineering of symmetry-protected sensors based on the skin
effect.Comment: 6 pages, 4 figures + Supplemental Materia
A Comprehensive Analysis of Fermi Gamma-Ray Burst Data. IV. Spectral Lag and its Relation to E p Evolution
The spectral evolution and spectral lag behavior of 92 bright pulses from 84 gamma-ray bursts observed by the Fermi Gamma-ray Burst Monitor (GBM) telescope are studied. These pulses can be classified into hard-to-soft pulses (H2S; 64/92), H2S-dominated-tracking pulses (21/92), and other tracking pulses (7/92). We focus on the relationship between spectral evolution and spectral lags of H2S and H2S-dominated-tracking pulses. The main trend of spectral evolution (lag behavior) is estimated with ( ), where E p is the peak photon energy in the radiation spectrum, t + t 0 is the observer time relative to the beginning of pulse −t 0, and is the spectral lag of photons with energy E with respect to the energy band 8–25 keV. For H2S and H2S-dominated-tracking pulses, a weak correlation between and k E is found, where W is the pulse width. We also study the spectral lag behavior with peak time of pulses for 30 well-shaped pulses and estimate the main trend of the spectral lag behavior with . It is found that is correlated with k E . We perform simulations under a phenomenological model of spectral evolution, and find that these correlations are reproduced. We then conclude that spectral lags are closely related to spectral evolution within the pulse. The most natural explanation of these observations is that the emission is from the electrons in the same fluid unit at an emission site moving away from the central engine, as expected in the models invoking magnetic dissipation in a moderately high-σ outflow
The newly observed structure and its mode nonstrange partners
Inspired by the newly observed structure, we investigate
its strong decay behaviors under various assignments within the model.
Compared with the mass and total decay width, our results suggest that the
can be regarded as the lowest mode excitation in
family. Then, the strong decays of mode nonstrange partners
for the are calculated. It is found that the
and states are relatively narrow, and mainly decay into
the and final states, respectively.
These two states have good potentials to be observed in future experiments,
which may help us to distinguish the three-quark model and diquark model.Comment: 8 pages, 4 figures, comments and suggestions are welcom
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