35,145 research outputs found
Study of and decays
We study the charmless two-body
and three-body decays. We obtain to agree with the
recent LHCb measurement. However, we find that is unable to explain the
LHCb observation of , which implies the possibility for other
contributions, such as that from the resonant decay with as a higher-wave baryon state. For
, we show that ,
which are consistent with the current data of , respectively. Our results also support the relation of ,
given by the previous study.Comment: 8 pages, 1 figure, revised version accepted by EPJ
Observational Test of Coronal Magnetic Field Models I. Comparison with Potential Field Model
Recent advances have made it possible to obtain two-dimensional line-of-sight
magnetic field maps of the solar corona from spectropolarimetric observations
of the Fe XIII 1075 nm forbidden coronal emission line. Together with the
linear polarization measurements that map the azimuthal direction of the
coronal magnetic field, these coronal vector magnetograms now allow for direct
observational testing of theoretical coronal magnetic field models. This paper
presents a study testing the validity of potential-field coronal magnetic field
models. We constructed a theoretical coronal magnetic field model of active
region AR 10582 observed by the SOLARC coronagraph in 2004 by a global
potential field extrapolation of the synoptic map of Carrington Rotation 2014.
Synthesized linear and circular polarization maps from thin layers of the
coronal magnetic field model above the active region along the line of sight
are compared with the observed maps. We found that reasonable agreement occurs
from layers located just above the sunspot of AR 10582, near the plane of the
sky. This result provides the first observational evidence that potential field
extrapolation can yield a reasonable approximation of the magnetic field
configuration of the solar corona for simple and stable active regions.Comment: 25 pages, 11 figures. ApJ in pres
Finite-size scaling of pseudo-critical point distributions in the random transverse-field Ising chain
We study the distribution of finite size pseudo-critical points in a
one-dimensional random quantum magnet with a quantum phase transition described
by an infinite randomness fixed point. Pseudo-critical points are defined in
three different ways: the position of the maximum of the average entanglement
entropy, the scaling behavior of the surface magnetization, and the energy of a
soft mode. All three lead to a log-normal distribution of the pseudo-critical
transverse fields, where the width scales as with and the
shift of the average value scales as with ,
which we related to the scaling of average and typical quantities in the
critical region.Comment: 4 pages, 2 figure
Recommended from our members
On the exceptional damage-tolerance of gradient metallic materials
An experimental study is described on the fracture toughness and micro-mechanisms associated with the initiation and propagation of cracks in metallic nickel containing marked gradients in grain size, ranging from ∼30 nm to ∼4 μm. Specifically, cracks are grown in a gradient structured (GS) nickel with grain-size gradient ranging from the coarse macro-scale to nano-scale (CG → NG) and vice versa (NG → CG), with the measured crack-resistance R-curves compared to the corresponding behavior in uniform nano-grained (NG) and coarse-grained (CG) materials. It is found that the gradient structures display a much-improved combination of high strength and toughness compared to uniform grain-sized materials. However, based on J-integral measurements in the gradient materials, the crack-initiation toughness is far higher for cracks grown in the direction of the coarse-to-nano grained gradient than vice versa, a result which we ascribe primarily to excessive crack-tip blunting in the coarse-grained microstructure. Both gradient structures, however, display marked rising R-curve behavior with exceptional crack-growth toughnesses exceeding 200 MPa.m½
- …