42,553 research outputs found
Direct CP violation in
We study the direct CP violation in the decay process in the
Standard Model. An interesting mechanism involving the charge symmetry
violating mixing between and is applied to enlarge the CP
asymmetry. With this mechanism, the maximum differential and localized
integrated CP asymmetries can reach and
, respectively, which still leave plenty room
for CP-violating New Physics to be discovered through this process
Analysis and Detection of Information Types of Open Source Software Issue Discussions
Most modern Issue Tracking Systems (ITSs) for open source software (OSS)
projects allow users to add comments to issues. Over time, these comments
accumulate into discussion threads embedded with rich information about the
software project, which can potentially satisfy the diverse needs of OSS
stakeholders. However, discovering and retrieving relevant information from the
discussion threads is a challenging task, especially when the discussions are
lengthy and the number of issues in ITSs are vast. In this paper, we address
this challenge by identifying the information types presented in OSS issue
discussions. Through qualitative content analysis of 15 complex issue threads
across three projects hosted on GitHub, we uncovered 16 information types and
created a labeled corpus containing 4656 sentences. Our investigation of
supervised, automated classification techniques indicated that, when prior
knowledge about the issue is available, Random Forest can effectively detect
most sentence types using conversational features such as the sentence length
and its position. When classifying sentences from new issues, Logistic
Regression can yield satisfactory performance using textual features for
certain information types, while falling short on others. Our work represents a
nontrivial first step towards tools and techniques for identifying and
obtaining the rich information recorded in the ITSs to support various software
engineering activities and to satisfy the diverse needs of OSS stakeholders.Comment: 41st ACM/IEEE International Conference on Software Engineering
(ICSE2019
A Comparative Study of Confined and Eruptive Flares in NOAA AR 10720
We investigate the distinct properties of two types of flares: eruptive
flares associated with CMEs and confined flares without CMEs. Our sample of
study includes nine M and X-class flares, all from the same active region (AR),
six of which are confined and three others are eruptive. The confined flares
tend to be more impulsive in the soft X-ray time profiles and show more slender
shapes in the EIT 195 A images, while the eruptive ones are of long-duration
events and show much more extended brightening regions. The location of the
confined flares are closer to the center of the AR, while the eruptive flares
are at the outskirts. This difference is quantified by the displacement
parameter, the distance between the AR center and the flare location: the
average displacement of the six confined flares is 16 Mm, while that of
eruptive ones is as large as 39 Mm. Further, through nonlinear force-free field
extrapolation, we find that the decay index of the transverse magnetic field in
the low corona (~10 Mm) have a larger value for eruptive flares than that for
confined one. In addition, the strength of the transverse magnetic field over
the eruptive flare sites is weaker than that over the confined ones. These
results demonstrate that the strength and the decay index of background
magnetic field may determine whether or not a flare be eruptive or confined.
The implication of these results on CME models is discussed in the context of
torus instability of flux rope.Comment: 23 pages, 8 figures, 2 tables, ApJ in pres
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