308,826 research outputs found
Polarized Curvature Radiation in Pulsar Magnetosphere
The propagation of polarized emission in pulsar magnetosphere is investigated
in this paper. The polarized waves are generated through curvature radiation
from the relativistic particles streaming along curved magnetic field lines and
co-rotating with the pulsar magnetosphere. Within the 1/{\deg} emission cone,
the waves can be divided into two natural wave mode components, the ordinary
(O) mode and the extraord nary (X) mode, with comparable intensities. Both
components propagate separately in magnetosphere, and are aligned within the
cone by adiabatic walking. The refraction of O-mode makes the two components
separated and incoherent. The detectable emission at a given height and a given
rotation phase consists of incoherent X-mode and O-mode components coming from
discrete emission regions. For four particle-density models in the form of
uniformity, cone, core and patches, we calculate the intensities for each mode
numerically within the entire pulsar beam. If the co-rotation of relativistic
particles with magnetosphere is not considered, the intensity distributions for
the X-mode and O-mode components are quite similar within the pulsar beam,
which causes serious depolarization. However, if the co-rotation of
relativistic particles is considered, the intensity distributions of the two
modes are very different, and the net polarization of out-coming emission
should be significant. Our numerical results are compared with observations,
and can naturally explain the orthogonal polarization modes of some pulsars.
Strong linear polarizations of some parts of pulsar profile can be reproduced
by curvature radiation and subsequent propagation effect.Comment: 12 pages, 9 figures, Accepted for publication in MNRA
QCD Evolutions of Twist-3 Chirality-Odd Operators
We study the scale dependence of twist-3 distributions defined with
chirality-odd quark-gluon operators. To derive the scale dependence we
explicitly calculate these distributions of multi-parton states instead of a
hadron. Taking one-loop corrections into account we obtain the leading
evolution kernel in the most general case. In some special cases the evolutions
are simplified. We observe that the obtained kernel in general does not get
simplified in the large- limit in contrast to the case of those twist-3
distributions defined only with chirality-odd quark operators. In the later,
the simplification is significant.Comment: 9 pages, 2 figure
Quantum phase transitions of polar molecules in bilayer systems
We investigate the quantum phase transitions of bosonic polar molecules in a
two-dimensional double layer system. We show that an interlayer bound state of
dipoles (dimers) can be formed when the dipole strength is above a critical
value, leading to a zero-energy resonance in the interlayer s-wave scattering
channel. In the positive detuning side of the resonance, the strong repulsive
interlayer pseudopotential can drive the system into a maximally entangled
state, where the wave function is a superposition of two states that have all
molecules in one layer and none in the other. We discuss how the zero-energy
resonance, dimer states, and the maximally entangled state can be measured in
time-of-flight experiments.Comment: Minor correction
Breakdown of QCD Factorization for P-Wave Quarkonium Production at Low Transverse Momentum
Quarkonium production at low transverse momentum in hadron collisions can be
used to extract Transverse-Momentum-Dependent(TMD) gluon distribution
functions, if TMD factorization holds there. We show that TMD factorization for
the case of P-wave quarkonium with holds at one-loop
level, but is violated beyond one-loop level. TMD factorization for other
P-wave quarkonium is also violated already at one-loop.Comment: Published version in Physics Letters B (2014), pp. 103-10
Transverse Momentum Dependent Factorization for Quarkonium Production at Low Transverse Momentum
Quarkonium production in hadron collisions at low transverse momentum
with as the quarkonium mass can be used for probing
transverse momentum dependent (TMD) gluon distributions. For this purpose, one
needs to establish the TMD factorization for the process. We examine the
factorization at the one-loop level for the production of or .
The perturbative coefficient in the factorization is determined at one-loop
accuracy. Comparing the factorization derived at tree level and that beyond the
tree level, a soft factor is, in general, needed to completely cancel soft
divergences. We have also discussed possible complications of TMD factorization
of p-wave quarkonium production.Comment: Title changed in the journal, published versio
Room-Temperature Ferrimagnet with Frustrated Antiferroelectricity: Promising Candidate Toward Multiple State Memory
On the basis of first-principles calculations we show that the M-type
hexaferrite BaFe12O19 exhibits frustrated antiferroelectricity associated with
its trigonal bipyramidal Fe3+ sites. The ferroelectric (FE) state of BaFe12O19,
reachable by applying an external electric field to the antiferroelectric (AFE)
state, can be made stable at room temperature by appropriate element
substitution or strain engineering. Thus M-type hexaferrite, as a new type of
multiferoic with coexistence of antiferroelectricity and ferrimagnetism,
provide a basis for studying the phenomenon of frustrated antiferroelectricity
and realizing multiple state memory devices.Comment: supporting material available via email. arXiv admin note: text
overlap with arXiv:1210.7116 by other author
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