719 research outputs found

    Evolving Indications for Tricuspid Valve Surgery

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    More attention has been paid to the mitral valve (MV) than the tricuspid valve (TV), and this relative paucity of data has led to confusion regarding the timing of TV surgery. We review the American College of Cardiology/American Heart Association and European Society of Cardiology guidelines to identify areas of concordance (severe tricuspid regurgitation [TR] in a patient undergoing mitral valve surgery); discordance (less than severe TR but with markers for late TR recurrence such as pulmonary hypertension, a dilated TV annulus, atrial fibrillation, permanent transtricuspid pacing wires and others); and disagreement (surgery for primary TR). We provide our perspective from Northwestern University on these issues and where the guidelines are silent (TR in patients undergoing non-mitral valve operations). Finally, we review recent publications on the results of TV repair and replacement. Although there have been scant publications in the past, there have been more useful publications in recent years to guide our decision making

    Search for the decay J/ψ→γ+invisibleJ/\psi\to\gamma + \rm {invisible}

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    We search for J/ψJ/\psi radiative decays into a weakly interacting neutral particle, namely an invisible particle, using the J/ψJ/\psi produced through the process ψ(3686)→π+π−J/ψ\psi(3686)\to\pi^+\pi^-J/\psi in a data sample of (448.1±2.9)×106(448.1\pm2.9)\times 10^6 ψ(3686)\psi(3686) decays collected by the BESIII detector at BEPCII. No significant signal is observed. Using a modified frequentist method, upper limits on the branching fractions are set under different assumptions of invisible particle masses up to 1.2  GeV/c2\mathrm{\ Ge\kern -0.1em V}/c^2. The upper limit corresponding to an invisible particle with zero mass is 7.0×10−7\times 10^{-7} at the 90\% confidence level

    Measurement of proton electromagnetic form factors in e+e−→ppˉe^+e^- \to p\bar{p} in the energy region 2.00-3.08 GeV

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    The process of e+e−→ppˉe^+e^- \rightarrow p\bar{p} is studied at 22 center-of-mass energy points (s\sqrt{s}) from 2.00 to 3.08 GeV, exploiting 688.5~pb−1^{-1} of data collected with the BESIII detector operating at the BEPCII collider. The Born cross section~(σppˉ\sigma_{p\bar{p}}) of e+e−→ppˉe^+e^- \rightarrow p\bar{p} is measured with the energy-scan technique and it is found to be consistent with previously published data, but with much improved accuracy. In addition, the electromagnetic form-factor ratio (∣GE/GM∣|G_{E}/G_{M}|) and the value of the effective (∣Geff∣|G_{\rm{eff}}|), electric (∣GE∣|G_E|) and magnetic (∣GM∣|G_M|) form factors are measured by studying the helicity angle of the proton at 16 center-of-mass energy points. ∣GE/GM∣|G_{E}/G_{M}| and ∣GM∣|G_M| are determined with high accuracy, providing uncertainties comparable to data in the space-like region, and ∣GE∣|G_E| is measured for the first time. We reach unprecedented accuracy, and precision results in the time-like region provide information to improve our understanding of the proton inner structure and to test theoretical models which depend on non-perturbative Quantum Chromodynamics

    First observations of hc→h_c \to hadrons

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    Based on (4.48±0.03)×108(4.48 \pm 0.03) \times 10^{8} ψ(3686)\psi(3686) events collected with the BESIII detector, five hch_c hadronic decays are searched for via process ψ(3686)→π0hc\psi(3686) \to \pi^0 h_c. Three of them, hc→ppˉπ+π−h_c \to p \bar{p} \pi^+ \pi^-, π+π−π0\pi^+ \pi^- \pi^0, and 2(π+π−)π02(\pi^+ \pi^-) \pi^0 are observed for the first time, with statistical significances of 7.4σ\sigma, 4.9σ4.9\sigma, and 9.1σ\sigma, and branching fractions of (2.89±0.32±0.55)×10−3(2.89\pm0.32\pm0.55)\times10^{-3}, (1.60±0.40±0.32)×10−3(1.60\pm0.40\pm0.32)\times10^{-3}, and (7.44±0.94±1.56)×10−3(7.44\pm0.94\pm1.56)\times10^{-3}, respectively, where the first uncertainties are statistical and the second systematic. No significant signal is observed for the other two decay modes, and the corresponding upper limits of the branching fractions are determined to be B(hc→3(π+π−)π0)<8.7×10−3B(h_c \to 3(\pi^+ \pi^-) \pi^0)<8.7\times10^{-3} and B(hc→K+K−π+π−)<5.8×10−4B(h_c \to K^+ K^- \pi^+ \pi^-)<5.8\times10^{-4} at 90% confidence level.Comment: 17 pages, 16 figure

    Precise Measurements of Branching Fractions for Ds+D_s^+ Meson Decays to Two Pseudoscalar Mesons

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    We measure the branching fractions for seven Ds+D_{s}^{+} two-body decays to pseudo-scalar mesons, by analyzing data collected at s=4.178∼4.226\sqrt{s}=4.178\sim4.226 GeV with the BESIII detector at the BEPCII collider. The branching fractions are determined to be B(Ds+→K+η′)=(2.68±0.17±0.17±0.08)×10−3\mathcal{B}(D_s^+\to K^+\eta^{\prime})=(2.68\pm0.17\pm0.17\pm0.08)\times10^{-3}, B(Ds+→η′π+)=(37.8±0.4±2.1±1.2)×10−3\mathcal{B}(D_s^+\to\eta^{\prime}\pi^+)=(37.8\pm0.4\pm2.1\pm1.2)\times10^{-3}, B(Ds+→K+η)=(1.62±0.10±0.03±0.05)×10−3\mathcal{B}(D_s^+\to K^+\eta)=(1.62\pm0.10\pm0.03\pm0.05)\times10^{-3}, B(Ds+→ηπ+)=(17.41±0.18±0.27±0.54)×10−3\mathcal{B}(D_s^+\to\eta\pi^+)=(17.41\pm0.18\pm0.27\pm0.54)\times10^{-3}, B(Ds+→K+KS0)=(15.02±0.10±0.27±0.47)×10−3\mathcal{B}(D_s^+\to K^+K_S^0)=(15.02\pm0.10\pm0.27\pm0.47)\times10^{-3}, B(Ds+→KS0π+)=(1.109±0.034±0.023±0.035)×10−3\mathcal{B}(D_s^+\to K_S^0\pi^+)=(1.109\pm0.034\pm0.023\pm0.035)\times10^{-3}, B(Ds+→K+π0)=(0.748±0.049±0.018±0.023)×10−3\mathcal{B}(D_s^+\to K^+\pi^0)=(0.748\pm0.049\pm0.018\pm0.023)\times10^{-3}, where the first uncertainties are statistical, the second are systematic, and the third are from external input branching fraction of the normalization mode Ds+→K+K−π+D_s^+\to K^+K^-\pi^+. Precision of our measurements is significantly improved compared with that of the current world average values

    Measurements of Weak Decay Asymmetries of Λc+→pKS0\Lambda_c^+\to pK_S^0, Λπ+\Lambda\pi^+, Σ+π0\Sigma^+\pi^0, and Σ0π+\Sigma^0\pi^+

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    Using e+e−→Λc+Λˉc−e^+e^-\to\Lambda_c^+\bar\Lambda_c^- production from a 567 pb−1^{-1} data sample collected by BESIII at 4.6 GeV, a full angular analysis is carried out simultaneously on the four decay modes of Λc+→pKS0\Lambda_c^+\to pK_S^0, Λπ+\Lambda \pi^+, Σ+π0\Sigma^+\pi^0, and Σ0π+\Sigma^0\pi^+. For the first time, the Λc+\Lambda_c^+ transverse polarization is studied in unpolarized e+e−e^+e^- collisions, where a non-zero effect is observed with a statistical significance of 2.1σ\sigma. The decay asymmetry parameters of the Λc+\Lambda_c^+ weak hadronic decays into pKS0pK_S^0, Λπ+\Lambda\pi^+, Σ+π0\Sigma^+\pi^0 and Σ0π+\Sigma^0\pi^+ are measured to be 0.18±0.43(stat)±0.14(syst)0.18\pm0.43(\rm{stat})\pm0.14(\rm{syst}), −0.80±0.11(stat)±0.02(syst)-0.80\pm0.11(\rm{stat})\pm0.02(\rm{syst}), −0.57±0.10(stat)±0.07(syst)-0.57\pm0.10(\rm{stat})\pm0.07(\rm{syst}), and −0.73±0.17(stat)±0.07(syst)-0.73\pm0.17(\rm{stat})\pm0.07(\rm{syst}), respectively. In comparison with previous results, the measurements for the Λπ+\Lambda\pi^+ and Σ+π0\Sigma^+\pi^0 modes are consistent but with improved precision, while the parameters for the pKS0pK_S^0 and Σ0π+\Sigma^0\pi^+ modes are measured for the first time

    Feasibility studies for the measurement of time-like proton electromagnetic form factors from p¯ p→ μ+μ- at P ¯ ANDA at FAIR

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    This paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors, | GE| and | GM| , using the p¯ p→ μ+μ- reaction at P ¯ ANDA (FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at P ¯ ANDA , using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is p¯ p→ π+π-, due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented

    Complete Measurement of the &#923; Electromagnetic Form Factors

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