1,690 research outputs found
Flavor Structure of the Nucleon Sea
We review the current status and future prospects on the subject of flavor
structure of the nucleon sea. The flavor structure of the nucleon sea provides
unique information on the non-perturbative aspects of strong interactions
allowing stringent tests of various models on the partonic structures of the
nucleons as well as lattice QCD calculations. The scope of this review covers
the unpolarized, polarized, and the transverse-momentum dependent sea-quark
distributions of the nucleons. While the main focus of this review is on the
physics motivation and recent progress on the subject of the nucleon sea, we
also discuss future prospects of addressing some outstanding issues on the
flavor structure of the nucleon sea.Comment: 61 pages and 36 figures; published versio
Interpretation of Angular Distributions of -boson Production at Colliders
High precision data of dilepton angular distributions in
production were reported recently by the CMS Collaboration covering a broad
range of the dilepton transverse momentum, , up to GeV.
Pronounced dependencies of the and parameters,
characterizing the and angular distributions, were
found. Violation of the Lam-Tung relation was also clearly observed. We show
that the dependence of allows a determination of the relative
contributions of the annihilation versus the Compton process.
The violation of the Lam-Tung relation is attributed to the presence of a
non-zero component of the axis in the direction normal to the
"hadron plane" formed by the colliding hadrons. The magnitude of the violation
of the Lam-Tung relation is shown to reflect the amount of this
`non-coplanarity". The observed dependencies of and from
the CMS and the earlier CDF data can be well described using this approach.Comment: 5 pages, 3 figure
A QoS aware services mashup model for cloud computing applications
Purpose: With the popularity of cloud computing, cloud services have become to be application programming platform where users can create new applications mashup(composing) the functionality offered byothers.By composing of distributed, cloud services dynamicallyto provide more complex tasks, services mashup provides an attractive way for building large-scale Internet applications.One of the challenging issues of cloud services mashup is how to find service paths to route the service instances provider through whilemeeting the applications’ resource requirements so that the QoS constraints are satisfied. However, QoS aware service routing problem istypically NP-hard.The purpose of this paper is to propose a QoS Aware Services Mashup(QASM) model to solve this problem more effectively.
Design/methodology/approach: In this paper, we focus on the QoS aware services selection problem in cloud services mashup, for example, given the user service composition requirements and their QoS constraint descriptions, how to select the required serviceinstances and route the data flows through these instances so that the QoS requirements are satisfied. We design a heuristic algorithm to find service paths to route the data flows through whilemeeting the applications’ resource requirements and specific QoS constraints.
Findings: This study propose a QoS Aware Services Mashup(QASM) model to solve this problem more effectively. Simulations show that QASM can achieve desired QoS assurances as well as load balancing in cloud services environment.
Originality/value: This paper present a QASM model for providing high performance distributed applications in the cloud computingPeer Reviewe
On the Rotational Invariance and Non-Invariance of Lepton Angular Distributions in Drell-Yan and Quarkonium Production
Several rotational invariant quantities for the lepton angular distributions
in Drell-Yan and quarkonium production were derived several years ago, allowing
the comparison between different experiments adopting different reference
frames. Using an intuitive picture for describing the lepton angular
distribution in these processes, we show how the rotational invariance of these
quantities can be readily obtained. This approach can also be used to determine
the rotational invariance or non-invariance of various quantities specifying
the amount of violation for the Lam-Tung relation. While the violation of the
Lam-Tung relation is often expressed by frame-dependent quantities, we note
that alternative frame-independent quantities are preferred.Comment: 4 pages, 1 figure, revised version, to appear in Phys. Lett
- …