Recent Higgs results from ATLAS

On behalf of the ATLAS CollaborationInternational audienceIn the context of the Standard Model and of scenarios beyond the Standard Model, results of Higgs boson searches of the ATLAS experiment are presented for 2010 and 2011 data. Combination of the Standard Model Higgs decay channels is shown for the 2010 data

Signatures of Spherical Compactification at the LHC

TeV-scale extra dimensions may play an important role in electroweak or supersymmetry breaking. We examine the phenomenology of such dimensions, compactified on a sphere $S^n$, $n \geq 2$, and show that they possess distinct features and signatures. For example, unlike flat toroidal manifolds, spheres do not trivially allow fermion massless modes. Acceptable phenomenology then generically leads to "non-universal" extra dimensions with "pole-localized" 4-$d$ fermions; the bosonic fields can be in the bulk. Due to spherical symmetry, some Kaluza-Klein (KK) modes of bulk gauge fields are either stable or extremely long-lived, depending on the graviton KK spectrum. Using precision electroweak data, we constrain the lightest gauge field KK modes to lie above $\simeq 4$ TeV. We show that some of these KK resonances are within the reach of the LHC in several different production channels. The models we study can be uniquely identified by their collider signatures.Comment: 21 pages, 5 fig

Heavy Ion Physics at the LHC with the ATLAS Detector

The ATLAS detector at CERN will provide a high-resolution longitudinally-segmented calorimeter and precision tracking for the upcoming study of heavy ion collisions at the LHC (sqrt(s_NN)=5520 GeV). The calorimeter covers |eta|<5 with both electromagnetic and hadronic sections, while the inner detector spectrometer covers |eta|<2.5. ATLAS will study a full range of observables necessary to characterize the hot and dense matter formed at the LHC. Global measurements (particle multiplicities, collective flow) will provide access into its thermodynamic and hydrodynamic properties. Measuring complete jets out to 100's of GeV will allow detailed studies of energy loss and its effect on jets. Quarkonia will provide a handle on deconfinement mechanisms. ATLAS will also study the structure of the nucleon and nucleus using forward physics probes and ultraperipheral collisions, both enabled by segmented Zero Degree Calorimeters.Comment: 9 pages, 8 figures, submitted to the Proceedings of Quark Matter 2006, Shanghai, China, November 14-20, 200

Les Houches "Physics at TeV Colliders 2003" Beyond the Standard Model Working Group: Summary Report

The work contained herein constitutes a report of the ``Beyond the Standard Model'' working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 26 May--6 June, 2003. The research presented is original, and was performed specifically for the workshop. Tools for calculations in the minimal supersymmetric standard model are presented, including a comparison of the dark matter relic density predicted by public codes. Reconstruction of supersymmetric particle masses at the LHC and a future linear collider facility is examined. Less orthodox supersymmetric signals such as non-pointing photons and R-parity violating signals are studied. Features of extra dimensional models are examined next, including measurement strategies for radions and Higgs', as well as the virtual effects of Kaluza Klein modes of gluons. An LHC search strategy for a heavy top found in many little Higgs model is presented and finally, there is an update on LHC $Z'$ studies.Comment: 113 pages, ed B.C. Allanach, v5 has changes to part XV

Electroweak Physics at LHC

The prospects for electroweak physics at the LHC are reviewed focusing mainly on precision studies. This includes projections for measurements of the effective Z pole weak mixing angle, of top quark, W boson, and Higgs scalar properties, and new physics searches

Measurement of the t-channel single top quark production cross section

The D0 collaboration reports direct evidence for electroweak production of single top quarks through the t-channel exchange of a virtual W boson. This is the first analysis to isolate an individual single top quark production channel. We select events containing an isolated electron or muon, missing transverse energy, and two, three or four jets from 2.3 fb^-1 of ppbar collisions at the Fermilab Tevatron Collider. One or two of the jets are identified as containing a b hadron. We combine three multivariate techniques optimized for the t-channel process to measure the t- and s-channel cross sections simultaneously. We measure cross sections of 3.14 +0.94 -0.80 pb for the t-channel and 1.05 +-0.81 pb for the s-channel. The measured t-channel result is found to have a significance of 4.8 standard deviations and is consistent with the standard model prediction.Comment: 7 pages, 6 figure

Measurement of the W boson mass

We present a measurement of the W boson mass in W -> ev decays using 1 fb^-1 of data collected with the D0 detector during Run II of the Fermilab Tevatron collider. With a sample of 499830 W -> ev candidate events, we measure M_W = 80.401 +- 0.043 GeV. This is the most precise measurement from a single experiment.Comment: As published in PR

Measurement of trilinear gauge boson couplings from WW + WZ to lnu jj events in pp-bar collisions at sqrt{s}=1.96 TeV

We present a direct measurement of trilinear gauge boson couplings at gammaWW and ZWW vertices in WW and WZ events produced in pp-bar collisions at sqrt{s}=1.96 TeV. We consider events with one electron or muon, missing transverse energy, and at least two jets. The data were collected using the D0 detector and correspond to 1.1/fb of integrated luminosity. Considering two different relations between the couplings at the gammaWW and ZWW vertices, we measure these couplings at 68% C.L. to be kappa_{gamma}=1.07^{+0.26}_{-0.29}, lambda =0.00^{+0.06}_{-0.06} and g_{1}^{Z}=1.04^{+0.09}_{-0.09} in a scenario respecting SU(2)_L x U(1)_Y gauge symmetry and kappa =1.04^{+0.11}_{-0.11} and lambda=0.00^{+0.06}_{-0.06} in an "equal couplings" scenario.Comment: 14 pages, 7 figures, published in Phys. Rev. D, updated to published versio

Measurements of differential cross sections of Z/gamma*+jets+X events in proton anti-proton collisions at sqrt{s}=1.96 TeV

We present cross section measurements for Z/gamma*+jets+X production, differential in the transverse momenta of the three leading jets. The data sample was collected with the D0 detector at the Fermilab Tevatron proton anti-proton collider at a center-of-mass energy of 1.96 TeV and corresponds to an integrated luminosity of 1 fb-1. Leading and next-to-leading order perturbative QCD predictions are compared with the measurements, and agreement is found within the theoretical and experimental uncertainties. We also make comparisons with the predictions of four event generators. Two parton-shower-based generators show significant shape and normalization differences with respect to the data. In contrast, two generators combining tree-level matrix elements with a parton shower give a reasonable description of the the shapes observed in data, but the predicted normalizations show significant differences with respect to the data, reflecting large scale uncertainties. For specific choices of scales, the normalizations for either generator can be made to agree with the measurements.Comment: Published in PLB. 11 pages, 3 figure

Search for resonant diphoton production with the D0 detector

We present a search for a narrow resonance in the inclusive diphoton final state using 2.7 fb-1 of data collected with the D0 detector at the Fermilab Tevatron ppbar Collider. We observe good agreement between the data and the background prediction, and set the first 95% C.L. upper limits on the production cross section times the branching ratio for decay into a pair of photons for resonance masses between 100 and 150 GeV. This search is also interpreted in the context of several models of electroweak symmetry breaking with a Higgs boson decaying into two photons.Comment: 7 pages, 3 figures