Polarized Fragmentation Functions

In this talk I present a review on the theoretical status of polarized fragmentation functions and the prospects for conceivable future semi-inclusive deep-inelastic scattering and proton-proton collision experiments to measure them.Comment: Talk at the Electron Polarized Ion Collider Workshop (EPIC99), at IUCF, Bloomington, IA, April 1999, 15 pp, 6 fig

Transversely polarized Drell-Yan asymmetry AT T at NLO

We present the first fully differential next-To-leading order QCD calculation for lepton production in transversely polarized hadronic collisions, p↑p↑→±X, where the lepton arises from the decay of an electroweak gauge boson. The calculation is implemented in the Monte-Carlo like code che that already includes the unpolarized and longitudinally polarized cross sections and may be readily used to perform a comparison to experimental data and to extract information on the related parton distributions. We analyze the perturbative stability of the cross-section and double spin asymmetry ATT at RHIC kinematics. We find that the QCD corrections are non-negligible even at the level of asymmetries and that they strongly depend on the lepton kinematics. Furthermore, we present two scenarios for transversely polarized parton distributions, based on the de Florian-Sassot-Stratmann-Vogelsang (DSSV) set of longitudinally parton densities and fully evolved to NLO accuracy, that can be used for the evaluation of different observables involving transverse polarization.Fil: de Florian, Daniel Enrique. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología. Centro Internacional de Estudios Avanzados; Argentina. Tübingen University; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Higgs Boson Pair Production at Next-to-Next-to-Leading Order in QCD

We compute the next-to-next-to-leading order QCD corrections for Standard Model Higgs boson pair production inclusive cross section at hadron colliders within the large top-mass approximation. We provide numerical results for the LHC, finding that the corrections are large, resulting in an increase of ${\cal O}(20$ with respect to the next-to-leading order result at c.m. energy $\sqrt{s_H}=14\,\text{TeV}$. We observe a substantial reduction in the scale dependence, with overlap between the current and previous order prediction. All our results are normalized using the full top- and bottom-mass dependence at leading order. We also provide analytical expressions for the K factors as a function of $s_H$

Jet Production with Polarized Beams at Next-to-Leading Order

Jet production cross-sections in polarized proton-proton and electron-proton collisions are studied to next-to-leading order accuracy. Phenomenological results are presented for RHIC and HERA kinematics.Comment: 3 pages, 4 figures, talk given at the DIS99 Workshop, Zeuthen, Germany, April 19-23, 199

Diphoton production at hadron colliders: transverse-momentum resummation at next-to-next-to-leading logarithmic accuracy

We consider the transverse-momentum (qT) distribution of a diphoton pair produced in hadron collisions. At small values of qT , we resum the logarithmically-enhanced perturbative QCD contributions up to next-to-next-to-leading logarithmic accuracy. At intermediate and large values of qT, we consistently combine resummation with the known next-to-leading order perturbative result. All perturbative terms up to order \alpha_S^2 are included in our computation which, after integration over qT, reproduces the known next-to-next-to-leading order result for the diphoton pair production total cross section. We present a comparison with LHC data and an estimate of the perturbative accuracy of the theoretical calculation by performing the corresponding variation of scales. In general we observe that the effect of the resummation is not only to recover the predictivity of the calculation at small transverse momentum, but also to improve substantially the agreement with the experimental data.Comment: 17 pages, 16 figures. arXiv admin note: text overlap with arXiv:1007.235

Jet production in Polarized DIS at NNLO

We present the NNLO calculation for single-inclusive jet production in polarized DIS $\vec{e}\vec{p} \rightarrow {\rm jet} +X$. We perform the computation based on the Projection-to-Born method by combining our recent NLO result for di-jet production in polarized DIS along with the NNLO coefficients for the inclusive cross section. In this way, we achieve NNLO accuracy in a fully exclusive way for single-jet observables, the first time for a polarized cross section. We study the perturbative stability and phenomenological consequences of the QCD corrections for Electron Ion Collider kinematics.Comment: 5 pages, 3 figure

Higgs boson pair production at NNLO in QCD including dimension 6 operators

In this paper, we present the computation of the Higgs boson pair production cross section, both inclusive as well as differential on the invariant mass distribution, at next-to-next-to-leading order (NNLO) in QCD including effects of new physics beyond the standard model. We parametrize the effects of new physics with the relevant dimension 6 operators in a standard model effective field theory (EFT) approach and examine their phenomenology. The dependence of the NNLO $K$-factor on the EFT couplings is analysed, finding that, while rather flat for a number of EFT coefficients, it can considerably differ from the standard model value in some particular regions of the parameter space. We present explicit examples of (almost) degeneracy in the NNLO cross-section with respect to the anomalous couplings, showing that the invariant mass distribution has a much larger sensitivity to phenomena beyond the standard model and can be used as a tool to discriminate their effect.Comment: 19 pages, 4 figures; typos corrected, references added, appendix with additional formulae adde

Global Analysis of Fragmentation Functions for Protons and Charged Hadrons

We present new sets of fragmentation functions for protons and inclusive charged hadrons obtained in combined NLO QCD analyses of single-inclusive hadron production in electron-positron annihilation, proton-proton collisions, and deep-inelastic lepton-proton scattering. These analyses complement previous results for pion and kaon fragmentation functions with charge and flavor discrimination. The Lagrange multiplier technique is used to assess the uncertainties in the extraction of the new sets of fragmentation functions.Comment: 14 pages, 14 figure

Next-to-Next-to-Leading Order QCD Corrections to Higgs Boson Pair Production

We present the Higgs boson pair production cross section at next-to-next-to-leading order in QCD within the large top-mass approximation. Numerical results for the LHC are provided, finding an increase of O(20%) with respect to the previous order prediction and a substantial reduction in the scale dependence. We normalize our results using the full top- and bottom-mass dependence at leading order.Comment: Proceedings of 'Loops & Legs 2014', Weimar (Germany), April/May 201