3,470 research outputs found
The Importance of Proper Renormalization Scale-Setting for Testing QCD at Colliders
A primary problem for perturbative QCD analyses is how to set the
renormalization scale of the QCD running coupling in order to achieve maximally
precise fixed-order predictions for physical observables. The Principle of
Maximum Conformality (PMC) eliminates the ambiguities associated with the
conventional renormalization scale-setting procedure, giving predictions which
are independent of the choice of renormalization scheme. The scales of the QCD
couplings and the effective number of quark flavors are set order by order in
the pQCD series. The PMC has a solid theoretical foundation, satisfying the
standard renormalization group invariance and all of the the self-consistency
conditions derived from the renormalization group......In this brief report, we
summarize the results of our recent PMC applications for a number of collider
processes, emphasizing their generality and applicability....... These results
demonstrate that the application of the PMC systematically eliminates a major
theoretical uncertainty for pQCD predictions, thus increasing the sensitivity
of the colliders to possible new physics beyond the Standard Model.Comment: 10 pages, 4 figures. The title has been changed. This review,
submitted to Frontiers of Physics, is based on a contribution by S.J.B. at
the Conference {\it Workshop on Physics at a Future High Intensity Collider @
2-7 GeV in China} Hefei, China January 14-16, 201
STG2Seq: Spatial-temporal Graph to Sequence Model for Multi-step Passenger Demand Forecasting
Multi-step passenger demand forecasting is a crucial task in on-demand
vehicle sharing services. However, predicting passenger demand over multiple
time horizons is generally challenging due to the nonlinear and dynamic
spatial-temporal dependencies. In this work, we propose to model multi-step
citywide passenger demand prediction based on a graph and use a hierarchical
graph convolutional structure to capture both spatial and temporal correlations
simultaneously. Our model consists of three parts: 1) a long-term encoder to
encode historical passenger demands; 2) a short-term encoder to derive the
next-step prediction for generating multi-step prediction; 3) an
attention-based output module to model the dynamic temporal and channel-wise
information. Experiments on three real-world datasets show that our model
consistently outperforms many baseline methods and state-of-the-art models.Comment: 7 page
A precise determination of the top-quark pole mass
The Principle of Maximum Conformality (PMC) provides a systematic way to
eliminate the renormalization scheme and renormalization scale uncertainties
for high-energy processes. We have observed that by applying PMC scale-setting,
one obtains comprehensive and self-consistent pQCD predictions for the
top-quark pair total cross-section and the top-quark pair forward-backward
asymmetry in agreement with the measurements at the Tevatron and LHC. As a step
forward, in the present paper, we determine the top-quark pole mass via a
detailed comparison of the top-quark pair cross-section with the measurements
at the Tevatron and LHC. The results for the top-quark pole mass are
GeV for the Tevatron with TeV,
GeV and GeV for the LHC with TeV
and TeV, respectively. Those predictions agree with the average,
GeV, obtained from various collaborations via direct
measurements. The consistency of the pQCD predictions using the PMC with all of
the collider measurements at different energies provides an important
verification of QCD.Comment: 10 pages, 6 figures. Revised version to be published in Eur.Phys.J.
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