Determination of the strong coupling constant using subjet multiplicities in Neutral Current Deep Inelastic Scattering

The internal structure of the jets produced in neutral current interactions for Q^2>125 GeV^2 has been studied using the subjet multiplicity with the ZEUS detector at HERA. Jets are identified in the laboratory frame by applying the longitudinally invariant k_T-cluster algorithm. Next-to-leading order QCD calculations have been obtained and compared to the data; a good agreement has been observed in the region where hadron-to-parton corrections are small, E_{T,jet}> 25 GeV. In this region, the strong coupling constant is extracted and the resulting value is alpha_s (M_Z)=0.1185 +/- 0.0016 (stat.) ^{+0.0067}_{-0.0048} (syst.) ^{+0.0089}_{-0.0071} (th.).Comment: 5 pages, 2 figures, to be published in the Proceedings of the DIS-2001 Worksho

LHC Results Highlights (CLASHEP 2013)

The good performance of the LHC provided enough data at 7 TeV and 8 TeV to allow the experiments to perform very competitive measurements and to expand the knowledge about the fundamental interaction far beyond that from previous colliders. This report summarizes the highlights of the results obtained with these data samples by the four large experiments, covering all the topics of the physics program and focusing on those exploiting the possibilities of the LHC.Comment: Lectures given at the 7th CERN-Latin-American School of High-Energy Physics, Arequipa, Peru, March 2013. Submitted for publication in a CERN Yellow Repor

Nickel-hydrogen separator development

The separator technology is a critical element in the nickel-hydrogen (Ni-H2) systems. Previous research and development work carried out at NASA Lewis Research Center has determined that separators made from zirconium oxide (ZrO2) and potassium titanate (PKT) fibers will function satisfactorily in Ni-H2 cells without exhibiting the problems associated with the asbestos separators. These separators and their characteristics were previously discussed. A program was established to transfer the separator technology into a commercial production line. A detailed plan of this program will be presented and the preliminary results will be discussed

Present Bounds on New Neutral Vector Resonances from Electroweak Gauge Boson Pair Production at the LHC

Several extensions of the Standard Model predict the existence of new neutral spin-1 resonances associated to the electroweak symmetry breaking sector. Using the data from ATLAS (with integrated luminosity of L=1.02 fb^{-1}) and CMS (with integrated luminosity of L=1.55 fb^{-1}) on the production of W+W- pairs through the process pp -> l^+ l^{\prime -} \sla{E}_T, we place model independent bounds on these new vector resonances masses, couplings and widths. Our analyses show that the present data excludes new neutral vector resonances with masses up to 1-2.3 TeV depending on their couplings and widths. We also demonstrate how to extend our analysis framework to different models working a specific example.Comment: 10 pages, 6 figure

Constraining anomalous Higgs interactions

The recently announced Higgs discovery marks the dawn of the direct probing of the electroweak symmetry breaking sector. Sorting out the dynamics responsible for electroweak symmetry breaking now requires probing the Higgs interactions and searching for additional states connected to this sector. In this work we analyze the constraints on Higgs couplings to the standard model gauge bosons using the available data from Tevatron and LHC. We work in a model--independent framework expressing the departure of the Higgs couplings to gauge bosons by dimension--six operators. This allows for independent modifications of its couplings to gluons, photons and weak gauge bosons while still preserving the Standard Model (SM) gauge invariance. Our results indicate that best overall agreement with data is obtained if the cross section of Higgs production via gluon fusion is suppressed with respect to its SM value and the Higgs branching ratio into two photons is enhanced, while keeping the production and decays associated to couplings to weak gauge bosons close to their SM prediction.Comment: v3: Added acknowledgment to FP7 ITN INVISIBLES (Marie Curie Actions PITN-GA-2011-289442). Nothing else changed with respect to v

Transverse parton momenta in single inclusive hadron production in e+e−{e^ + }{e^ - } annihilation processes

We study the transverse momentum distributions of single inclusive hadron production in ${e^ + }{e^ - }$ annihilation processes. Although the only available experimental data are scarce and quite old, we find that the fundamental features of transverse momentum dependent (TMD) evolution, historically addressed in Drell-Yan processes and, more recently, in Semi-inclusive deep inelastic scattering processes, are visible in ${e^ + }{e^ - }$ annihilations as well. Interesting effects related to its non-perturbative regime can be observed. We test two different parameterizations for the $p_\perp$ dependence of the cross section: the usual Gaussian distribution and a power-law model. We find the latter to be more appropriate in describing this particular set of experimental data, over a relatively large range of $p_\perp$ values. We use this model to map some of the features of the data within the framework of TMD evolution, and discuss the caveats of this and other possible interpretations, related to the one-dimensional nature of the available experimental data