arXiv subjects

Anselm Vossen

Publications and source records attributed to Anselm Vossen.

25 records · Page 2Linked to original sources

arXiv2016

The RHIC Cold QCD Plan for 2017 to 2023: A Portal to the EIC

The exploration of the fundamental structure of strongly interacting matter has always thrived on the complementarity of lepton scattering and purely hadronic probes. As the community eagerly anticipates a future electron ion collider (EIC) in the U.S., an outstanding scientific opportunity remains to complete "must-do" measurements in p+p and p+A physics in the years preceding the EIC. As we describe in this document, these measurements will be essential to fully realize the scientific promise of the EIC by provid-ing a comprehensive set of measurements in hadronic collisions that, when combined with data from the EIC, will establish the validity and limits of factorization and universality. The outlined program will on the one hand lay the groundwork for the EIC, both scientifically and in terms of refining the experimental requirements for the physics program at the EIC, and thus be the natural next step on the path towards an electron-ion collider. On the other hand, while much of the physics in this program is unique to proton-proton and proton-nucleus collisions and offers discovery potential on its own, when combined with data from the EIC it will provide a broad foundation to a deeper understanding of fundamental QCD.

nucl-ex↗

arXiv2015

The RHIC SPIN Program: Achievements and Future Opportunities

Time and again, spin has been a key element in the exploration of fundamental physics. Spin-dependent observables have often revealed deficits in the assumed theoretical framework and have led to novel developments and concepts. Spin is exploited in many parity-violating experiments searching for physics beyond the Standard Model or studying the nature of nucleon-nucleon forces. The RHIC spin program plays a special role in this grand scheme: it uses spin to study how a complex many-body system such as the proton arises from the dynamics of QCD. Many exciting results from RHIC spin have emerged to date, most of them from RHIC running after the 2007 Long Range Plan. In this document we present highlights from the RHIC program to date and lay out the roadmap for the significant advances that are possible with future RHIC running.

nucl-ex↗

arXiv2013

The RHIC Spin Program: Achievements and Future Opportunities

This document summarizes recent achievements of the RHIC spin program and their impact on our understanding of the nucleon's spin structure, i.e. the individual parton (quark and gluon) contributions to the helicity structure of the nucleon and to understand the origin of the transverse spin phenomena. Open questions are identified and a suite of future measurements with polarized beams at RHIC to address them is laid out. Machine and detector requirements and upgrades are briefly discussed.

nucl-ex↗

arXiv2009

First Measurement of the Interference Fragmentation Function in $e^+e^-$ at Belle

A first measurement of the di-hadron interference fragmentation function of light quarks in pion pairs with the Belle detector is presented. The chiral odd nature of this fragmentation function allows the use as a quark polarimeter sensitive to the transverse polarization of the fragmenting quark. Therefore it can be used together with data taken at fixed target and collider experiments to extract the quark transversity distribution. A sample consisting of $711 \times 10^6$ di-hadron pairs was extracted from 661 $fb^{-1}$ of data recorded near the $Υ(4S)$ resonance delivered by the KEKB $e^+$$e^{-}$ collider.

hep-ex↗

arXiv2008

Basics of Feature Selection and Statistical Learning for High Energy Physics

This document introduces basics in data preparation, feature selection and learning basics for high energy physics tasks. The emphasis is on feature selection by principal component analysis, information gain and significance measures for features. As examples for basic statistical learning algorithms, the maximum a posteriori and maximum likelihood classifiers are shown. Furthermore, a simple rule based classification as a means for automated cut finding is introduced. Finally two toolboxes for the application of statistical learning techniques are introduced.

physics.data-an↗

arXiv2008

Support Vector Machines in High Energy Physics

This lecture will introduce the Support Vector algorithms for classification and regression. They are an application of the so called kernel trick, which allows the extension of a certain class of linear algorithms to the non linear case. The kernel trick will be introduced and in the context of structural risk minimization, large margin algorithms for classification and regression will be presented. Current applications in high energy physics will be discussed.

physics.data-an↗

arXiv2007

Measurement of Transverse Spin Effects at COMPASS

By measuring transverse single spin asymmetries one has access to the transversity distribution function $Δ_T q(x)$ and the transverse momentum dependent Sivers function $q_0^T(x,\vec{k}_T)$. New measurements from identified hadrons and hadron pairs, produced in deep inelastic scattering of a transversely polarized $^6LiD$ target are presented. The data were taken in 2003 and 2004 by the COMPASS collaboration using the muon beam of the CERN SPS at 160 GeV/c, resulting in small asymmetries.

hep-ex↗