Double transverse spin asymmetries in vector boson production

We investigate a helicity non-flip double transverse spin asymmetry in vector boson production in hadron-hadron scattering, which was first considered by Ralston and Soper at the tree level. It does not involve transversity functions and in principle also arises in W-boson production for which we present the expressions. The asymmetry requires observing the transverse momentum of the vector boson, but it is not suppressed by explicit inverse powers of a large energy scale. However, as we will show, inclusion of Sudakov factors causes suppression of the asymmetry, which increases with energy. Moreover, the asymmetry is shown to be approximately proportional to x_1 g_1(x_1) x_2 \bar g_1(x_2), which gives rise to additional suppression at small values of the light cone momentum fractions. This implies that it is negligible for Z or W production and is mainly of interest for \gamma^* at low energies. We also compare the asymmetry with other types of double transverse spin asymmetries and discuss how to disentangle them.Comment: 12 pages, Revtex, 2 Postscript figures, uses aps.sty, epsf.sty; figures replaced, a few minor other correction

The impact of a 126 GeV Higgs on the neutralino mass

We highlight the differences of the dark matter sector between the constrained minimal supersymmetric SM (CMSSM) and the next-to-minimal supersymmetric SM (NMSSM) including the 126 GeV Higgs boson using GUT scale parameters. In the dark matter sector the two models are quite orthogonal: in the CMSSM the WIMP is largely a bino and requires large masses from the LHC constraints. In the NMSSM the WIMP has a large singlino component and is therefore independent of the LHC SUSY mass limits. The light NMSSM neutralino mass range is of interest for the hints concerning light WIMPs in the Fermi data. Such low mass WIMPs cannot be explained in the CMSSM. Furthermore, prospects for discovery of XENON1T and LHC at 14 TeV are given.Comment: 18 pages, 5 figures, this version is accepted by PLB after modifications including additional figure

Factorisation, Parton Entanglement and the Drell-Yan Process

We discuss the angular distribution of the lepton pair in the Drell-Yan process, hadron+hadron -> \gamma^* X -> l^+ l^- X. This process gives information on the spin-density matrix \rho^{(q,\bar{q})} of the annihilating quark-antiquark pair in q+\bar{q} -> l^+ l^-. There is strong experimental evidence that even for unpolarised initial hadrons \rho^{(q,\bar{q})} is nontrivial, and therefore the quark-antiquark system is polarised. We discuss the possibilities of a general \rho^{(q,\bar{q})} -which could be entangled- and a factorising \rho^{(q,\bar{q})}. We argue that instantons may lead to a nontrivial \rho^{(q,\bar{q})} of the type indicated by experiments.Comment: 14 pages, 2 figures, comments and references added; to appear in EPJ

Spin asymmetries in jet-hyperon production at LHC

We consider polarized Lambda hyperon production in proton-proton scattering, p p -> (\Lambda^\uparrow jet) jet X, in the kinematical region of the LHC experiments, in particular the ALICE experiment. We present a new Lambda polarization observable that arises from the Sivers effect in the fragmentation process. It can be large even at midrapidity and therefore, is of interest for high energy hadron collider experiments. Apart from its potential to shed light on the mechanisms behind the phenomenon of Lambda polarization arising in unpolarized hadronic collisions, the new observable in principle also allows to test the possible color flow dependence of single spin asymmetries and the (non)universality of transverse momentum dependent fragmentation functions.Comment: 11 pages, 10 eps figures; minor modifications, conclusions unchanged, version to be publishe

Can we discover a light singlet-like NMSSM Higgs boson at the LHC?

In the next-to minimal supersymmetric standard model (NMSSM) one additional singlet-like Higgs boson with small couplings to standard model (SM) particles is introduced. Although the mass can be well below the discovered 125 GeV Higgs boson mass its small couplings may make a discovery at the LHC difficult. We use a novel scanning technique to efficiently scan the whole parameter space and determine the range of cross sections and branching ratios for the light singlet-like Higgs boson below 125 GeV. This allows to determine the perspectives for the future discovery potential at the LHC. Specific LHC benchmark points are selected representing the salient NMSSM features.Comment: 22 pages, 5 figures, this version is accepted by PLB after minor modification