分类： 图书馆学、情报学 >> 情报学 提交时间： 2016-08-16
摘要： [目的/意义] 通过优化提出一个可精准识别睡美人文献的简易无参数指标。[方法/过程] 借鉴睡美人指数（B指数）基本框架，通过将考察对象“年度被引次数”优化为“年度被引次数累积百分比”，提出Bcp指数，重新定义唤醒时间、睡眠深度和唤醒强度。并通过识别Science和Nature上的睡美人文献进行检验。[结果/结论] Bcp指数继承了B指数对那些非常显著的睡美人文献高度敏感的优点。Bcp指数框架下计算出的唤醒时间更符合实际情况，而B指数框架下的唤醒时间易被延迟估计。Bcp指数考虑了观察期内论文全部的引文曲线，规避了B指数无法反映年度被引次数达到最大值以后的引文曲线的缺点。Bcp指数对论文发表之初被引次数的约束效力显著高于B指数，更符合睡美人文献早期零被引和低被引的特征。Bcp指数对年龄大、总被引次数和年度被引次数相对较低的睡美人文献更敏感，有利于挖掘平常易被忽视的非高被引文献中睡美人文献的存在规律。Bcp指数规避了人为参数主观界定的不足，以及不同学科领域论文被引规模差异对睡美人文献统一定义的干扰。
分类： 物理学 >> 核物理学 提交时间： 2016-08-16
摘要： A search for a massive resonance W' decaying into a W and a Higgs boson in the l nu b anti-b (l = e, mu) final state is presented. Results are based on data corresponding to an integrated luminosity of 19.7 inverse femtobarns of proton-proton collisions at sqrt(s) = 8 TeV, collected using the CMS detector at the LHC. For a high-mass ( greater than 1 TeV) resonance, the two bottom quarks coming from the Higgs boson decay are reconstructed as a single jet, which can be tagged by placing requirements on its substructure and flavour. Exclusion limits at 95% confidence level are set on the production cross section of a narrow resonance decaying into WH, as a function of its mass. In the context of a little Higgs model, a lower limit on the W' mass of 1.4 TeV is set. In a heavy vector triplet model that mimics the properties of composite Higgs models, a lower limit on the W' mass of 1.5 TeV is set. In the context of this model, the results are combined with related searches to obtain a lower limit on the W' mass of 1.8 TeV, the most restrictive to date for decays to a pair of standard model bosons.
分类： 物理学 >> 核物理学 提交时间： 2016-08-16
摘要： A new search signature for excited leptons is explored. Excited muons are sought in the channel pp→μμ∗→μμ jet jet, assuming both the production and decay occur via a contact interaction. The analysis is based on 20.3 fb−1 of pp collision data at a centre-of-mass energy of s√ = 8 TeV taken with the ATLAS detector at the Large Hadron Collider. No evidence of excited muons is found, and limits are set at the 95% confidence level on the cross section times branching ratio as a function of the excited-muon mass mμ∗. For mμ∗ between 1.3 TeV and 3.0 TeV, the upper limit on σB(μ∗→μqq¯) is between 0.6 and 1 fb. Limits on σB are converted to lower bounds on the compositeness scale Λ. In the limiting case Λ=mμ∗, excited muons with a mass below 2.8 TeV are excluded. With the same model assumptions, these limits at larger μ∗ masses improve upon previous limits from traditional searches based on the gauge-mediated decay μ∗→μγ.
分类： 物理学 >> 核物理学 提交时间： 2016-08-16
摘要： A measurement of the forward-backward asymmetry A[FB] of oppositely charged lepton pairs (mu mu and e e) produced via Z/gamma* boson exchange in pp collisions at sqrt(s) = 8 TeV is presented. The data sample corresponds to an integrated luminosity of 19.7 inverse femtobarns collected with the CMS detector at the LHC. The measurement of A[FB] is performed for dilepton masses between 40 GeV and 2 TeV and for dilepton rapidity up to 5. The A[FB] measurements as a function of dilepton mass and rapidity are compared with the standard model predictions.
分类： 物理学 >> 核物理学 提交时间： 2016-08-16
摘要： The CDEX-1 experiment conducted a search of low-mass (< 10 GeV/c2) Weakly Interacting Massive Particles (WIMPs) dark matter at the China Jinping Underground Laboratory using a p-type point-contact germanium detector with a fiducial mass of 915 g at a physics analysis threshold of 475 eVee. We report the hardware set-up, detector characterization, data acquisition and analysis procedures of this experiment. No excess of unidentified events are observed after subtraction of known background. Using 335.6 kg-days of data, exclusion constraints on the WIMP-nucleon spin-independent and spin-dependent couplings are derived.
点击量
待评议
点击量
下载量
评论
