21,900 research outputs found

    Kaon and pion parton distribution amplitudes to twist-three

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    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 BcB_c Meson to a P-Wave Charmonium State χc\chi_c or hch_c

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    The semileptonic decays of meson BcB_c to a P-wave charmonium state χc(3PJ)\chi_c(^3P_J) or hc(1P1)h_c(^1P_1) 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 1P1^1P_1 charmonium state potentially offers us a novel window to see the unconfirmed hch_c particle. In addition, it is pointed out that since the two charmonium radiative decays χc(3P1,2)J/ψ+γ\chi_c(^3P_{1,2}) \to J/\psi+\gamma have sizable branching ratios, the cascade decays of the concerned decays and the charmonium radiative decays may affect the result of the observing the BcB_c meson through the semileptonic decays BcJ/ψ+l+νlB_{c}\to {J/\psi}+{l}+\nu_{l} substantially.Comment: 8 pages, 2 figure

    Quantum state transmission via a spin ladder as a robust data bus

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    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

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    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

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    We present algorithms that compute the terminal configurations for sandpile instances in O(nlogn)O(n \log n) time on trees and O(n)O(n) time on paths, where nn 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 O(nlog5n)O(n \log^5 n) on trees [Ramachandran-Schild SODA '17] and O(nlogn)O(n \log n) 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 PP. The reduction gives a time complexity of O(logPnT)O(\log^{|P|} n \cdot T) where TT denotes the total time for solving on each subgraph. In addition, we give algorithms in O(n)O(n) time on cliques and O(nlog2n)O(n \log^2 n) time on pseudotrees.Comment: 66 pages, submitted to SODA2
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