125952490
The Expected Performance of the ATLAS Inner Detector
122689361
Search for New Phenomena with the Monojet and Missing Transverse Momentum Signature Using the ATLAS Detector in $\sqrt{s}=7$ TeV Proton-Proton Collisions
A search for new phenomena in events featuring a high energy jet and large missing transverse momentum in proton-proton collisions at root s = 7 TeV is presented using a dataset corresponding to an integrated luminosity of 33 pb(-1) recorded with the ATLAS detector at the Large Hadron Collider. The number of observed events is consistent with the Standard Model prediction. This result is interpreted in terms of limits on a model of Large Extra Dimensions. (C) 2011 CERN. Published by Elsevier B.V. All rights reserved.
123566403
Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using 4.7 fb-1 of √s = 7 TeV proton-proton collision data
A search for squarks and gluinos in final states containing jets, missing transverse momentum and no high-p(T) electrons or muons is presented. The data represent the complete sample recorded in 2011 by the ATLAS experiment in 7 TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 4.7 fb(-1). No excess above the Standard Model background expectation is observed. Gluino masses below 860 GeV and squark masses below 1320 GeV are excluded at the 95% confidence level in simplified models containing only squarks of the first two generations, a gluino octet and a massless neutralino, for squark or gluino masses below 2 TeV, respectively. Squarks and gluinos with equal masses below 1410 GeV are excluded. In minimal supergravity/constrained minimal supersymmetric Standard Model models with tan beta = 10, A(0) = 0 and mu > 0, squarks and gluinos of equal mass are excluded for masses below 1360 GeV. Constraints are also placed on the parameter space of supersymmetric models with compressed spectra. These limits considerably extend the region of supersymmetric parameter space excluded by previous measurements with the ATLAS detector.
123114924
ATLAS measurements of the properties of jets for boosted particle searches
Measurements are presented of the properties of high transverse momentum jets, produced in proton-proton collisions at a center-of-mass energy of root s = 7 TeV. The data correspond to an integrated luminosity of 35 pb(-1) and were collected with the ATLAS detector in 2010. Jet mass, width, eccentricity, planar flow and angularity are measured for jets reconstructed using the anti-k(t) algorithm with distance parameters R 0: 6 and 1.0, with transverse momentum p(T) > 300 GeV and pseudorapidity vertical bar eta vertical bar < 2. The measurements are compared to the expectations of Monte Carlo generators that match leading-logarithmic parton showers to leading-order, or next-to-leading-order, matrix elements. The generators describe the general features of the jets, although discrepancies are observed in some distributions.
15635826
Near-Infrared Photometry of the Globular Cluster Palomar 6
We present JHK photometry of Palomar 6. Our photometric measurements range from the red giant branch (RGB) tip to ≈2 mag below the red horizontal branch (RHB), and our color-magnitude diagrams show that Palomar 6 appears to have a well-defined RHB population. The distance modulus and interstellar reddening of the cluster are estimated by comparing the magnitude and color of Palomar 6 RHB stars with those of 47 Tuc. We obtain (m - M)_0 = 14.28 mag and E(B-V) = 1.30 mag for the cluster, and our study suggests that Palomar 6 is clearly located in the Galaxy's central regions. We also discuss the metallicity of the cluster using the slope of the RGB. We obtain [Fe/H] ≈ -1.2 for Palomar 6 and our metallicity estimate is ≈0.5–1.0 dex lower than previous estimates by others.
119253557
Listening to Noise
We show how sign problems in simulations of many-body systems can manifest themselves in the form of heavy-tailed correlator distributions, similar to what is seen in electron propagation through disordered media. We propose an alternative statistical approach for extracting ground state energies in such systems, illustrating the method with a toy model and with lattice data for unitary fermions and for baryons in QCD.
40146055
Measurement of forward-backward asymmetry and Wilson coefficients in B --> K*l+l-.
We report the first measurement of the forward-backward asymmetry and the ratios of Wilson coefficients and in A9/A7 and A10/A7 in B --> K*l+l-, where l represents an electron or a muon. We find evidence for the forward-backward asymmetry with a significance of 3.4sigma. The results are obtained from a data sample containing 386 x 10(6) BB pairs that were collected on the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
6220935
Measurement of the neutron radius of 208Pb through parity violation in electron scattering.
We report the first measurement of the parity-violating asymmetry A(PV) in the elastic scattering of polarized electrons from 208Pb. A(PV) is sensitive to the radius of the neutron distribution (R(n)). The result A(PV)=0.656±0.060(stat)±0.014(syst) ppm corresponds to a difference between the radii of the neutron and proton distributions R(n)-R(p)=0.33(-0.18)(+0.16) fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.
119193937
Factorization in exclusive quarkonium production
We present factorization theorems for two exclusive heavy-quarkonium production processes: production of two quarkonia in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation and production of a quarkonium and a light meson in $B$-meson decays. We describe the general proofs of factorization and supplement them with explicit one-loop analyses, which illustrate some of the features of the soft-gluon cancellations. We find that violations of factorization are generally suppressed relative to the factorized contributions by a factor ${v}^{2}{m}_{c}/Q$ for each $S$-wave charmonium and a factor ${m}_{c}/Q$ for each $L$-wave charmonium with $Lg0$. Here, $v$ is the velocity of the heavy quark or antiquark in the quarkonium rest frame, $Q=\sqrt{s}$ for ${e}^{+}{e}^{\ensuremath{-}}$ annihilation, $Q={m}_{B}$ for $B$-meson decays, $\sqrt{s}$ is the ${e}^{+}{e}^{\ensuremath{-}}$ center-of-momentum energy, ${m}_{c}$ is the charm-quark mass, and ${m}_{B}$ is the $B$-meson mass. There are modifications to the suppression factors if quantum-number restrictions apply for the specific process.