21,900 research outputs found
Kaon and pion parton distribution amplitudes to twist-three
We compute all kaon and pion parton distribution amplitudes (PDAs) to
twist-three and find that only the pseudotensor PDA can reasonably be
approximated by its conformal limit expression. At terrestrially accessible
energy scales, the twist-two and pseudoscalar twist-three PDAs differ
significantly from those functions commonly associated with their forms in
QCD's conformal limit. In all amplitudes studied, SU(3) flavour-symmetry
breaking is typically a 13% effect. This scale is determined by nonperturbative
dynamics; namely, the current-quark-mass dependence of dynamical chiral
symmetry breaking. The heavier-quark is favoured by this distortion, for
example, support is shifted to the s-quark in the negative kaon. It appears,
therefore, that at energy scales accessible with existing and foreseeable
facilities, one may obtain reliable expectations for experimental outcomes by
using these "strongly dressed" PDAs in formulae for hard exclusive processes.
Following this procedure, any discrepancies between experiment and theory will
be significantly smaller than those produced by using the conformal-limit PDAs.
Moreover, the magnitude of any disagreement will either be a better estimate of
higher-order, higher-twist effects or provide more realistic constraints on the
Standard Model.Comment: 14 pages, 4 figures, 2 tables. arXiv admin note: text overlap with
arXiv:1406.335
Semileptonic Decays of Meson to a P-Wave Charmonium State or
The semileptonic decays of meson to a P-wave charmonium state
or are computed. The results show that the decays
are sizable so they are accessible in Tevatron and in LHC, especially, with the
detectors LHCB and BTeV in the foreseeable future, and of them, the one to the
charmonium state potentially offers us a novel window to see the
unconfirmed particle. In addition, it is pointed out that since the two
charmonium radiative decays have sizable
branching ratios, the cascade decays of the concerned decays and the charmonium
radiative decays may affect the result of the observing the meson through
the semileptonic decays substantially.Comment: 8 pages, 2 figure
Quantum state transmission via a spin ladder as a robust data bus
We explore the physical mechanism to coherently transfer the quantum
information of spin by connecting two spins to an isotropic antiferromagnetic
spin ladder system as data bus. Due to a large spin gap existing in such a
perfect medium, the effective Hamiltonian of the two connected spins can be
archived as that of Heisenberg type, which possesses a ground state with
maximal entanglement. We show that the effective coupling strength is inversely
proportional to the distance of the two spins and thus the quantum information
can be transferred between the two spins separated by a longer distance, i.e.
the characteristic time of quantum state transferring linearly depends on the
distance.Comment: 7 pages, 5 figures, 1 tabl
Pilot Study of Labor Induction with Titrated oral Misoprostol
SummaryObjectiveTo evaluate the safety and efficacy of titrated oral misoprostol for labor induction at term.Materials and MethodsSeventy-seven pregnant women (37 nullipara and 40 multipara), with medical or obstetric indications for labor induction after 37 weeks of gestation and unfavorable cervices (Bishop's score < 7), were induced according to the principles of titrated oral doses of misoprostol against uterine response. Our primary outcome measurements were the percentage of patients who had a vaginal delivery within 24 hours of induction and the interval from induction to vaginal delivery. Secondary measurements included oxytocin requirement, total misoprostol dosage, number of cesarean deliveries, induction failure, uterine hyper-stimulation rates and neonatal outcomes.ResultsSeventy-five women (97.4%) experienced active labor within 24 hours, with 72 (93.5%) completing vaginal delivery within 24 hours. The mean interval from induction to vaginal delivery for all the women was 9.7 hours, with a 2.3-hour active phase. The mean misoprostol dosage was 206 mg, with eight women (10.4%) requiring oxytocin augmentation. There was no uterine hyperstimulation or induction failure, except for seven cases of uterine tachysystole (9.1%).ConclusionTitrated oral misoprostol is a safe and effective method of labor induction because the dosage can be adjusted according to individual response
Sandpile Prediction on Structured Undirected Graphs
We present algorithms that compute the terminal configurations for sandpile
instances in time on trees and time on paths, where is
the number of vertices. The Abelian Sandpile model is a well-known model used
in exploring self-organized criticality. Despite a large amount of work on
other aspects of sandpiles, there have been limited results in efficiently
computing the terminal state, known as the sandpile prediction problem.
Our algorithm improves the previous best runtime of on trees
[Ramachandran-Schild SODA '17] and on paths [Moore-Nilsson '99].
To do so, we move beyond the simulation of individual events by directly
computing the number of firings for each vertex. The computation is accelerated
using splittable binary search trees. We also generalize our algorithm to adapt
at most three sink vertices, which is the first prediction algorithm faster
than mere simulation on a sandpile model with sinks.
We provide a general reduction that transforms the prediction problem on an
arbitrary graph into problems on its subgraphs separated by any vertex set .
The reduction gives a time complexity of where
denotes the total time for solving on each subgraph. In addition, we give
algorithms in time on cliques and time on pseudotrees.Comment: 66 pages, submitted to SODA2
- …