WW mass and width measurements at the Tevatron

Most recent results of $W$ boson mass and width measurements performed by CDF and D are reported. at the center-of-mass energy of 1.96 TeV. Integrated luminosity ranges from 0.2 fb$^{-1}$ to 1.0 fb$^{-1}$ depending on the analysis.Comment: The XXIV Rencontres de Physique de la Vallee d'Aoste Conference, La Thuile, Italy, March 201

W Mass results from Tevatron and LHC

Most recent results of $W$ boson mass measurements from Tevatron experiments (CDF and D0) in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ GeV are reported, using $0.2 fb^{-1}$ and $1.0 fb^{-1}$ data collected at CDF and D0, respectively. The measurements of $W$ boson properties at LHC experiments (ATLAS, CMS, and LHCb) in $pp$ collisions at $\sqrt{s}=7$ TeV, using data collected before Summer 2011, are presented. These measurements are essential at the preparation stage of the $W$ boson mass measurements at LHC. Challenges for $W$ mass measurement at the LHC in comparison with the Tevatron are outlined. Prospects for $W$ mass precision with upcoming measurements and its implications are discussed.Comment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011), Paris, France, November 14-18 2011, 4 pages, 13 figure

Flavor Asymmetries in the Proton and Semi-Inclusive Processes

Semi-inclusive electron scattering provides a powerful tool with which to study the spin and flavor distributions in the proton. Greater kinematic coverage at the proposed Electron-Polarized Ion Collider facility will enable the valence d/u ratio to be determined at large x through pion production. At small x, pion production can be used to extract the d-bar/u-bar ratio, complementing existing semi-inclusive measurements by HERMES, and Drell-Yan data from Fermilab. Asymmetries in heavier quark flavors can also be probed by tagging strange and charm hadrons in the final state.Comment: 15 pages, 6 figures, presented at the Electron-Polarized Ion Collider Workshop, IUCF, April 199

D0 Search for the Higgs Boson in Multijet Events

We present two searches for the Higgs boson in \sqrt{s} = 1.96 TeV p\bar{p}collisions using data taken with the \dz detector during Run II of the Fermilab Tevatron collider. The first study is a search for neutral Higgs bosons produced in association with bottom quarks. We set upper limits on the production of neutral Higgs bosons in the mass range of 90 to 150 GeV.The second study is a search for the standard model Higgs boson produced in association with the Z boson. We study the p\bar{p}\to ZH \to \nu \bar{\nu} b \bar{b} channel, which is one of the most sensitive ways to search for light Higgs bosons at the Tevatron. We search for a peak in invariant mass distribution of two b-tagged jets. After subtracting the backgrounds, we set the 95% C.L. upper limits on the \sigma(p\bar{p} \to ZH \to \nu \bar{\nu}) \times BR(H) \to b\bar{b}) for Higgs masses between 105 and 135 GeV.Comment: 3 pages, 2 figures, PANIC2005, to be published in AIP proceeding

Quark-hadron duality in electron-pion scattering

We explore the relationship between exclusive and inclusive electromagnetic scattering from the pion, focusing on the transition region at intermediate Q^2. Combining Drell-Yan data on the leading twist quark distribution in the pion with a model for the resonance region at large x, we calculate QCD moments of the pion structure function over a range of Q^2, and quantify the role of higher twist corrections. Using a parameterization of the pion elastic form factor and phenomenological models for the pi -> rho transition form factor, we further test the extent to which local duality may be valid for the pion.Comment: 23 pages, 7 figures, to appear in Eur. J. Phys.

Nucleon structure at large x: nuclear effects in deuterium

I review quark momentum distributions in the nucleon at large momentum fractions x. Particular attention is paid to the impact of nuclear effects in deuterium on the d/u quark distribution ratio as x -> 1. A new global study of parton distributions, using less restrictive kinematic cuts in Q^2 and W^2, finds strong suppression of the d quark distribution once nuclear corrections are accounted for.Comment: to appear in Achievements and New Directions in Subatomic Physics: Festschrift in Honour of Tony Thomas' 60th Birthday, Adelaide, Australia, 15-19 Feb. 2010, ed. W. Melnitchou

Quark-Hadron Duality in Electron Scattering

Quark-hadron duality addresses some of the most fundamental issues in strong interaction physics, in particular the nature of the transition from the perturbative to non-perturbative regions of QCD. I summarize recent developments in quark-hadron duality in lepton-hadron scattering, and outline how duality can be studied at future high-luminosity facilities such as Jefferson Lab at 12 GeV, or an electron-hadron collider such as EPIC.Comment: 5 pages, 2 figures, talk presented at the Second Workshop on Physics with an Electron Polarized Light-Ion Collider (EPIC), MIT, Sep.14-16, 200

QCD and the Structure of the Nucleon in Electron Scattering

The internal structure of the nucleon is discussed within the context of QCD. Recent progress in understanding the distribution of flavor and spin in the nucleon is reviewed, and prospects for extending our knowledge of nucleon structure in electron scattering experiments at modern facilities such as Jefferson Lab are outlined.Comment: 52 pages, 11 figures, lectures presented at the 1999 Hampton University Graduate Studies (HUGS) summer school, Jefferson La

Flavor Decomposition of the Nucleon

I review some recent developments in the study of quark flavor distributions in the nucleon, including (i) valence quark distributions and the quark-hadron duality prediction for the x -> 1 d/u ratio (ii) sea quark asymmetries and electromagnetic form factors (iii) strange quarks in the nucleon.Comment: 12 pages, 6 figures, extended version of talk presented at the Workshop on Exclusive & Semi-Exclusive Processes at High Momentum Transfer, Jefferson Lab, June 1999; minor typos correcte

Asymmetric Quarks in the Proton

Asymmetries in the quark momentum distributions in the proton reveal fundamental aspects of strong interaction physics. Differences between u-bar and d-bar quarks in the proton sea provide insight into the dynamics of the pion cloud around the nucleon and the nature of chiral symmetry breaking. Polarized flavor asymmetries allow the effects of pion clouds to be disentangled from those of antisymmetrization. Asymmetries between s and s-bar quark distributions in the nucleon are also predicted from the chiral properties of QCD.Comment: 7 pages, 2 figures, talk presented at the 3rd International Symposium on Symmetries in Subatomic Physics, Adelaide, Australia, March 200