1,029 research outputs found

    On plane wave and vortex-like solutions of noncommutative Maxwell-Chern-Simons theory

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    We investigate the spectrum of the gauge theory with Chern-Simons term on the noncommutative plane, a modification of the description of the Quantum Hall fluid recently proposed by Susskind. We find a series of the noncommutative massive ``plane wave'' solutions with polarization dependent on the magnitude of the wave-vector. The mass of each branch is fixed by the quantization condition imposed on the coefficient of the noncommutative Chern-Simons term. For the radially symmetric ansatz a vortex-like solution is found and investigated. We derive a nonlinear difference equation describing these solutions and we find their asymptotic form. These excitations should be relevant in describing the Quantum Hall transitions between plateaus and the end transition to the Hall Insulator.Comment: 17 pages, LaTeX (JHEP), 1 figure, added references, version accepted to JHE

    Search for Invisible Decays of η\eta and η′\eta^\prime in J/ψ→ϕηJ/\psi \to \phi\eta and ϕη′\phi \eta^\prime

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    Using a data sample of 58×10658\times 10^6 J/ψJ/\psi decays collected with the BES II detector at the BEPC, searches for invisible decays of η\eta and η′\eta^\prime in J/ψJ/\psi to ϕη\phi\eta and ϕη′\phi\eta^\prime are performed. The ϕ\phi signals, which are reconstructed in K+K−K^+K^- final states, are used to tag the η\eta and η′\eta^\prime decays. No signals are found for the invisible decays of either η\eta or η′\eta^\prime, and upper limits at the 90% confidence level are determined to be 1.65×10−31.65 \times 10^{-3} for the ratio B(η→invisible)B(η→γγ)\frac{B(\eta\to \text{invisible})}{B(\eta\to\gamma\gamma)} and 6.69×10−26.69\times 10^{-2} for B(η′→invisible)B(η′→γγ)\frac{B(\eta^\prime\to \text{invisible})}{B(\eta^\prime\to\gamma\gamma)}. These are the first searches for η\eta and η′\eta^\prime decays into invisible final states.Comment: 5 pages, 4 figures; Added references, Corrected typo

    Ethnic differences translate to inadequacy of high-risk screening for gestational diabetes mellitus in an Asian population: a cohort study

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    Background: universal and high-risk screening for gestational diabetes mellitus (GDM) has been widely studied and debated. Few studies have assessed GDM screening in Asian populations and even fewer have compared Asian ethnic groups in a single multi-ethnic population.Methods: 1136 pregnant women (56.7% Chinese, 25.5% Malay and 17.8% Indian) from the Growing Up in Singapore Towards healthy Outcomes (GUSTO) birth cohort study were screened for GDM by 75-g oral glucose tolerance test (OGTT) at 26–28 weeks of gestation. GDM was defined using the World Health Organization (WHO) criteria. High-risk screening is based on the guidelines of the UK National Institute for Health and Clinical Excellence.Results: universal screening detected significantly more cases than high-risk screening [crude OR 2.2 (95% CI 1.7-2.8)], particularly for Chinese women [crude OR = 3.5 (95% CI 2.5-5.0)]. Pre-pregnancy BMI > 30 kg/m2 (adjusted OR = 3.4, 95% CI 1.5-7.9) and previous GDM history (adjusted OR = 6.6, 95% CI 1.2-37.3) were associated with increased risk of GDM in Malay women while GDM history was the only significant risk factor for GDM in Chinese women (adjusted OR = 4.7, 95% CI 2.0-11.0).Conclusion: risk factors used in high-risk screening do not sufficiently predict GDM risk and failed to detect half the GDM cases in Asian women. Asian women, particularly Chinese, should be screened to avoid under-diagnosis of GDM and thereby optimize maternal and fetal outcome

    Radiofrequency ablation versus hepatic resection for hepatocellular carcinoma within the Milan criteria – A comparative study

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    AbstractBackgroundTo compare the results of radiofrequency ablation (RFA) with hepatic resection in the treatment of hepatocellular carcinoma (HCC) within the Milan criteria.MethodsA nonrandomized comparative study was performed with 111 consecutive patients who underwent laparoscopic RFA (n = 31) or curative hepatic resection (n = 80) for HCC within Milan criteria.ResultsProcedure related complications were less often and severe after RFA than resection (3.2% vs. 25%). There was no significant difference in hospital mortality (0% vs. 3.8%). Hospital stay was significantly shorter in the RFA group than in the resection group (mean, 3.8 vs. 6.8 days). The 1-, 3-, and 5-year disease-free survival rates for the RFA group and the resection group were 76%, 40%, 40% and 76%, 60%, 60%, respectively. Disease-free survival was significantly lower in the RFA group than in the resection group. The corresponding 1-, 3-, and 5-year overall survival rates for the RFA group and the resection group were 100%, 92%, 84%, and 92%, 75%, 71%, respectively. The overall survival for RFA and resection were not significantly different.ConclusionsOur result showed comparable overall survival between RFA and surgery, although RFA was associated with a significantly higher tumor recurrence rate. RFA had the advantages over surgical resection in being less invasive and having lower morbidity

    Scaling violations: Connections between elastic and inelastic hadron scattering in a geometrical approach

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    Starting from a short range expansion of the inelastic overlap function, capable of describing quite well the elastic pp and pˉp\bar{p}p scattering data, we obtain extensions to the inelastic channel, through unitarity and an impact parameter approach. Based on geometrical arguments we infer some characteristics of the elementary hadronic process and this allows an excellent description of the inclusive multiplicity distributions in pppp and pˉp\bar{p}p collisions. With this approach we quantitatively correlate the violations of both geometrical and KNO scaling in an analytical way. The physical picture from both channels is that the geometrical evolution of the hadronic constituents is principally reponsible for the energy dependence of the physical quantities rather than the dynamical (elementary) interaction itself.Comment: 16 pages, aps-revtex, 11 figure

    Partial wave analysis of J/\psi \to \gamma \phi \phi

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    Using 5.8×107J/ψ5.8 \times 10^7 J/\psi events collected in the BESII detector, the radiative decay J/ψ→γϕϕ→γK+K−KS0KL0J/\psi \to \gamma \phi \phi \to \gamma K^+ K^- K^0_S K^0_L is studied. The ϕϕ\phi\phi invariant mass distribution exhibits a near-threshold enhancement that peaks around 2.24 GeV/c2c^{2}. A partial wave analysis shows that the structure is dominated by a 0−+0^{-+} state (η(2225)\eta(2225)) with a mass of 2.24−0.02+0.03−0.02+0.032.24^{+0.03}_{-0.02}{}^{+0.03}_{-0.02} GeV/c2c^{2} and a width of 0.19±0.03−0.04+0.060.19 \pm 0.03^{+0.06}_{-0.04} GeV/c2c^{2}. The product branching fraction is: Br(J/ψ→γη(2225))⋅Br(η(2225)→ϕϕ)=(4.4±0.4±0.8)×10−4Br(J/\psi \to \gamma \eta(2225))\cdot Br(\eta(2225)\to \phi\phi) = (4.4 \pm 0.4 \pm 0.8)\times 10^{-4}.Comment: 11 pages, 4 figures. corrected proof for journa

    Interacting new agegraphic viscous dark energy with varying GG

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    We consider the new agegraphic model of dark energy with a varying gravitational constant, GG, in a non-flat universe. We obtain the equation of state and the deceleration parameters for both interacting and noninteracting new agegraphic dark energy. We also present the equation of motion determining the evolution behavior of the dark energy density with a time variable gravitational constant. Finally, we generalize our study to the case of viscous new agegraphic dark energy in the presence of an interaction term between both dark components.Comment: 12 pages, accepted for publication in IJTP (2010

    Search for the Rare Decays J/Psi --> Ds- e+ nu_e, J/Psi --> D- e+ nu_e, and J/Psi --> D0bar e+ e-

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    We report on a search for the decays J/Psi --> Ds- e+ nu_e + c.c., J/Psi --> D- e+ nu_e + c.c., and J/Psi --> D0bar e+ e- + c.c. in a sample of 5.8 * 10^7 J/Psi events collected with the BESII detector at the BEPC. No excess of signal above background is observed, and 90% confidence level upper limits on the branching fractions are set: B(J/Psi --> Ds- e+ nu_e + c.c.)<4.8*10^-5, B(J/Psi --> D- e+ nu_e + c.c.) D0bar e+ e- + c.c.)<1.1*10^-5Comment: 10 pages, 4 figure

    A study of charged kappa in J/ψ→K±Ksπ∓π0J/\psi \to K^{\pm} K_s \pi^{\mp} \pi^0

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    Based on 58×10658 \times 10^6 J/ψJ/\psi events collected by BESII, the decay J/ψ→K±Ksπ∓π0J/\psi \to K^{\pm} K_s \pi^{\mp} \pi^0 is studied. In the invariant mass spectrum recoiling against the charged K∗(892)±K^*(892)^{\pm}, the charged κ\kappa particle is found as a low mass enhancement. If a Breit-Wigner function of constant width is used to parameterize the kappa, its pole locates at (849±77−14+18)−i(256±40−22+46)(849 \pm 77 ^{+18}_{-14}) -i (256 \pm 40 ^{+46}_{-22}) MeV/c2c^2. Also in this channel, the decay J/ψ→K∗(892)+K∗(892)−J/\psi \to K^*(892)^+ K^*(892)^- is observed for the first time. Its branching ratio is (1.00±0.19−0.32+0.11)×10−3(1.00 \pm 0.19 ^{+0.11}_{-0.32}) \times 10^{-3}.Comment: 14 pages, 4 figure
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