Implications of QCD radiative corrections on high-pT Higgs searches

We discuss the effect of next-to-leading order (NLO) QCD corrections to the Higgsstrahlung process, where the Higgs boson decays to bottom quarks, using a partonic-level fully differential code. First we evaluate the impact of initial- and final-state gluon radiation on the reconstruction of a mass peak with the fat-jet analysis in the boosted regime at the LHC with sqrt(s) = 14 TeV as proposed in Butterworth et al. (2008) [1]. Finally we study the current CMS search strategy for this channel and compare it to the fat-jet procedure at the LHC with sqrt(s) = 8 TeV. Both show that final-state QCD radiation has a sizable effect and should be taken properly into account.Comment: 16 pages, 5 figures, version accepted for publicatio

Sustainable production of Ham

Sustainable Production of “HAM”​ is not actually about sustainable pork or ham production. Instead, it discusses the 10 practices for sustainable agriculture, whathappens when we aren’t sustainable, and the Brundtland Report’s definition ofsustainable agriculture, all to the tune of Hamilton’s ​The World Was Wide Enough.1_tdlrzuf

Does the `Higgs' have Spin Zero?

The Higgs boson is predicted to have spin zero. The ATLAS and CMS experiments have recently reported of an excess of events with mass ~ 125 GeV that has some of the characteristics expected for a Higgs boson. We address the questions whether there is already any evidence that this excess has spin zero, and how this possibility could be confirmed in the near future. The excess observed in the gamma gamma final state could not have spin one, leaving zero and two as open possibilities. We calculate the angular distribution of gamma gamma pairs from the decays of a spin-two boson produced in gluon-gluon collisions, showing that is unique and distinct from the spin-zero case. We also calculate the distributions for lepton pairs that would be produced in the W W* decays of a spin-two boson, which are very different from those in Higgs decays, and note that the kinematics of the event selection used to produce the excess observed in the W W* final state have reduced efficiency for spin two.Comment: 22 pages, 22 figures, Version accepted for publication in JHEP, includes additional plots of dilepton mass distribution

Background subtraction and jet quenching on jet reconstruction

In order to assess the ability of jet observables to constrain the characteristics of the medium produced in heavy-ion collisions at the LHC, we investigate the influence of background subtraction and jet quenching on jet reconstruction, with focus on the dijet asymmetry as currently studied by ATLAS and CMS. Using a toy model, we examine the influence of different background subtraction methods on dijet momentum imbalance and azimuthal distributions. We compare the usual jet-area based background subtraction technique and a variant of the noise-pedestal subtraction method used by CMS. The purpose of this work is to understand what are the differences between the two techniques, given the same event configuration. We analyze the influence of the quenching effect using the Q-PYTHIA Monte Carlo on the previous observables and to what extent Q-PYTHIA is able to reproduce the CMS data for the average missing transverse momentum that seems to indicate the presence of large angle emission of soft particles.Comment: 4 pages, 3 figures, Proceedings for Hard Probes 201

Weakness or Strength in the Golden Years of RHIC and LHC?

Recent LHC data suggest that perturbative QCD provides a qualitatively consistent picture of jet quenching. Constrained to RHIC pi0 suppression, zero parameter WHDG energy loss predictions agree quantitatively with the charged hadron v2 and D meson RAA measured at LHC and qualitatively with the charged hadron RAA. On the other hand, RHIC-constrained LHC predictions from fully strongly-coupled AdS/CFT qualitatively oversuppress D mesons compared to data; light meson predictions are on less firm theoretical ground but also suggest oversuppression. More detailed data from heavy, especially B, mesons will continue to help clarify our picture of the physics of the quark-gluon plasma. Since the approach of pQCD predictions to LHC data occurs at momenta >~ 15 GeV/c, a robust consistency check between pQCD and both RHIC and LHC data requires RHIC jet measurements.Comment: 4 pages. 3 figures. Proceedings for Hard Probes 2012. Minor grammatical and reference changes from v

Open charm and charmonium production at LHCb

We see copious production of charmed hadrons in the early LHCb data. The status and plans for charm production studies at LHCb are discussed, and preliminary signals are shown.Comment: 4 pages, 10 figures, to appear in the proceedings of the IX International Conference on Hyperons, Charm and Beauty Hadrons (BEACH 2010

Recent studies of top quark properties and decays at hadron colliders

The top quark is the heaviest known elementary particle. Observed for the first time in 1995 at the Tevatron by the CDF and D0 experiments, it has become object of several studies aimed at fully characterize its properties and decays. Precise determinations of top quark characteristics verify the internal consistency of the standard model and are sensitive to new physics phenomena. With the advent of the large top quark production rates generated at the LHC, top quark studies have reached unprecedented statistical precision. This review summarizes the recent measurements of top quark properties and studies of its decays performed at the LHC and Tevatron.Comment: 13 pages, 4 figures, 5 tables, Presented at Flavor Physics and CP Violation (FPCP 2012), Hefei, China, May 21-25, 201

Hadron Correlations Measured with ALICE

Angular particle correlations are a powerful tool to study collective effects and in-medium jet modification as well as their interplay in the hot and dense medium produced in central heavy-ion collisions. We present measurements of two-particle angular correlations of inclusive charged and identified particles performed with the ALICE detector. The near-side peak in the short-range correlation region is quantitatively analyzed: while the rms of the peak in $\phi$-direction is independent of centrality within uncertainties, we find a significant broadening in $\eta$-direction from peripheral to central collisions. The particle content of the near-side peak is studied finding that the $p/\pi$ ratio of particles associated to a trigger particle is much smaller than the one in the bulk of the particles and consistent with fragmentation of a parton in vacuum.Comment: Proceedings of plenary talk at the 5th international conference on hard and electromagnetic probes of high-energy nuclear collisions (Hard Probes 2012), Cagliari, Ital

Cross Section Ratios between different CM energies at the LHC: opportunities for precision measurements and BSM sensitivity

The staged increase of the LHC beam energy provides a new class of interesting observables, namely ratios and double ratios of cross sections of various hard processes. The large degree of correlation of theoretical systematics in the cross section calculations at different energies leads to highly precise predictions for such ratios. We present in this letter few examples of such ratios, and discuss their possible implications, both in terms of opportunities for precision measurements and in terms of sensitivity to Beyond the Standard Model dynamics.Comment: 19 pages, 9 figure

Where is SUSY?

The direct searches for Superymmetry at colliders can be complemented by direct searches for dark matter (DM) in underground experiments, if one assumes the Lightest Supersymmetric Particle (LSP) provides the dark matter of the universe. It will be shown that within the Constrained minimal Supersymmetric Model (CMSSM) the direct searches for DM are complementary to direct LHC searches for SUSY and Higgs particles using analytical formulae. A combined excluded region from LHC, WMAP and XENON100 will be provided, showing that within the CMSSM gluinos below 1 TeV and LSP masses below 160 GeV are excluded (m_{1/2} > 400 GeV) independent of the squark masses.Comment: 16 pages, 10 figure