The Spin Structure of the Nucleon

The present status of the nucleon's spin structure is reviewed with emphasis on new experimental results.Comment: Invited talk presented at the XIX International Symposium on Lepton and Photon Interactions, Stanford University, August 9-14, 1999, 16 pages, 15 figure

The QCD Spin Structure of Nucleons (Summary of Parallel Session 2)

This paper attempts to summarise the highlights of the talks presented in Parallel Session II of the SPIN 2004 Symposium dedicated to the QCD spin structure of nucleons. Emphasis is put on new data and theoretical developments.Comment: 10 pages, 14 Figures, Part of Spin 2004 Proceeding

Future Programme of COMPASS at CERN

COMPASS at CERN is preparing for a new series of measurements on the nucleon structure comprising deep virtual Compton scattering and hard exclusive meson production using muon beams, as well as Drell-Yan reactions using a polarised proton target and a negative pion beam. The former will mainly constrain the generalised parton distribution H and determine the transverse size of the nucleon, while the latter measurements will provide information on transverse-momentum dependent parton distribution functions. The projected results of the programme and the necessary hardware upgrades are discussed.Comment: 4 Pages, 5 figures, Proceedings of DIS2012, Bon

Deep inelastic scattering from unpolarised targets

In this paper the experimental status of unpolarised structure functions is reviewed. In particular the latest results from the NMC, E665, CCFR, and HERA experiments are discussed. Emphasis is put on the fixed-target experiments, which cover with high precision the x region relevant for the present polarised DIS experiments.Comment: 25 pages, LaTeX, Invited Talk given at the International School of Nucleon Structure, 1st Course: The Spin Structure of the Nucleon, Erice, Italy, 3--10 August 1995, to be published by World Scientifi

Why there is no crisis of the "spin crisis"

In a recent eprint [1] it is argued that the experimental determinations of the spin-dependent structure function g1 have been done incorrectly and that a reanalysis of those data suggests that the original motivation to argue fora "spin crisis", namely the small contribution of quark spins to the nucleon spin, is invalid. In a subsequent note [2] the theoretical understanding, as it has evolved from almost 30 years of theoretical and experimental scrutiny, has been shortly summarised. In this short note, arguments are presented that the line of reasoning in Ref. [1] does not apply, at least not for the Compass data.Comment: 2 pages, no figure

Spin Physics with COMPASS

The recently proposed COMPASS experiment at CERN attempts a measurement of the gluon polarisation with a precision of delta(Delta g/g) = 0.1. The experiment uses open charm muoproduction to tag the photon-gluon fusion process

Measurements of Delta G/G

Our present information on the gluon polarisation Delta g/g is reviewed. The data from fixed-target lepton-nucleon experiments are in context with the recent data from the RHIC polarised pp collider. The main tools to study Delta g/g in lepton-nucleon scattering are scaling violations of the g_1 structure functions and longitudinal spin asymmetries in hadron production. Results from high-p_T hadron pairs, inclusive hadrons as well as open-charm production are discussed. At RHIC the most precise data presently came from inclusive pi^0 and jet production. All data indicate that the gluon polarisation is small compared to earlier expectations, but still can make a major contribution to the nucleon spin.Comment: Proceedings for SPIN2006, Kyot

The Spin Structure of the Nucleon

This article reviews our present understanding of QCD spin physics: the proton spin puzzle and new developments aimed at understanding the transverse structure of the nucleon. We discuss present experimental investigations of the nucleon's internal spin structure, the theoretical interpretation of the different measurements and the open questions and challenges for future investigation.Comment: Review, 43 pages, 23 figures, to appear in Reviews of Modern Physic

Distinguishing Supersymmetry From Universal Extra Dimensions or Little Higgs Models With Dark Matter Experiments

There are compelling reasons to think that new physics will appear at or below the TeV-scale. It is not known what form this new physics will take, however. Although The Large Hadron collider is very likely to discover new particles associated with the TeV-scale, it may be difficult for it to determine the nature of those particles, whether superpartners, Kaluza-Klein modes or other states. In this article, we consider how direct and indirect dark matter detection experiments may provide information complementary to hadron colliders, which can be used to discriminate between supersymmetry, models with universal extra dimensions, and Little Higgs theories. We find that, in many scenarios, dark matter experiments can be effectively used to distinguish between these possibilities.Comment: 23 pages, 7 figures, references added in version