118864702
Affine Defects and Gravitation
We argue that the structure general relativity (GR) as a theory of affine defects is deeper than the standard interpretation as a metric theory of gravitation. Einstein–Cartan theory (EC), with its inhomogeneous affine symmetry, should be the standard-bearer for GR-like theories. A discrete affine interpretation of EC (and gauge theory) yields topological definitions of momentum and spin (and Yang–Mills current), and their conservation laws become discrete topological identities. Considerations from quantum theory provide evidence that discrete affine defects are the physical foundation for gravitation.
118897253
Translational Spacetime Symmetries in Gravitational Theories
How to include spacetime translations in fibre bundle gauge theories has been a subject of controversy, because spacetime symmetries are not internal symmetries of the bundle structure group. The standard method for including affine symmetry in differential geometry is to define a Cartan connection on an affine bundle over spacetime. This is equivalent to (1) defining an affine connection on the affine bundle, (2) defining a zero section on the associated affine vector bundle and (3) using the affine connection and the zero section to define an 'associated solder form', whose lift to a tensorial form on the frame bundle becomes the solder form. The zero section reduces the affine bundle to a linear bundle and splits the affine connection into translational and homogeneous parts; however, it violates translational equivariance/gauge symmetry. This is the natural geometric framework for Einstein–Cartan theory as an affine theory of gravitation. The last section discusses some alternative approaches that claim to preserve translational gauge symmetry.
119218875
Derivation of Einstein-Cartan theory from general relativity
General relativity cannot describe exchange of orbital angular momentum and intrinsic angular momentum (spin). In 1922 E. Cartan proposed extending general relativity by including affine torsion, which resolves this problem. In 1986 the author published a derivation of Einstein-Cartan theory from general relativity with classical spin, with no additional assumptions. This paper adds simpler explanations, more computational details of the proof of the main result, correction of a factor of 2, a summary of the evidence in support of Einstein-Cartan theory, and a discussion of comments about the derivation.
122778003
Study of energy response and resolution of the ATLAS barrel calorimeter to hadrons of energies from 20 to 350 GeV
A fully instrumented slice of the ATLAS detector was exposed to test beams from the SPS (Super Proton Synchrotron) at CERN in 2004. In this paper, the results of the measurements of the response of the barrel calorimeter to hadrons with energies in the range 20 to 350 GeV and beam impact points and angles corresponding to pseudorapidity values in the range 0.2-0.65 are reported. The results are compared to the predictions of a simulation program using the Geant 4 toolkit.
16999307
Modeling Lepton‐Nucleon Inelastic Scattering from High to Low Momentum Transfer
We present a model for inclusive charged lepton‐nucleon and (anti)neutrino‐nucleon cross sections at momentum transfer squared, Q2, ∼1 GeV2. We quantify the impact of existing low‐Q charged‐lepton deep‐inelastic scattering (DIS) data on effects due to high‐twist operators and on the extraction of parton distribution functions (PDFs). No evidence is found for twist‐6 contributions to structure functions (SF), and for a twist‐4 term in the longitudinal SF at x≳0.1. We find that DIS data are consistent with the NNLO QCD approximation with the target mass and phenomenological high twist corrections. For Q2<1 GeV2, we extend extrapolation of the operator product expansion, preserving the low‐Q current‐conservation theorems. The procedure yields a good description of data down to Q2∼0.5 GeV2. An updated set of PDFs with reduced uncertainty and applicable down to small momentum transfers in the lepton‐nucleon scattering is obtained.
119378999
Development of large size Micromegas detector for the upgrade of the ATLAS Muon system
With the luminosity upgrade of the LHC machine (SLHC), the Muon System of the ATLAS experiment at CERN will also need a detector upgrade in the highest rapidity region. An R&D activity (MAMMA, for Muon Atlas MicroMegas Activity) has started with the aim to develop large detectors based on the bulk-Micromegas technology to be used in the ATLAS Muon Spectrometer. Micormegas are good candidates to construct large muon chambers that combine trigger and tracking capability and can cope with the high particle rates expected at SLHC. A medium size Micromegas prototype has been built and evaluated in the laboratory and in beam tests at CERN. Results from tests and basic ideas of the ATLAS Muon upgrade using Micromegas are presented.
1529836
Search for a new gauge boson in π0 decays
Abstract A search was made for a new light gauge boson X which might be produced in π 0 → γ + X decay from neutral pions generated by 450 GeV protons in the CERN SPS neutrino target. The X's would penetrate the downstream shielding and be observed in the NOMAD detector via the Primakoff effect, in the process of X → π 0 conversion in the external Coulomb field of a nucleus. With 1.45×10 18 protons on target, 20 candidate events with energy between 8 and 140 GeV were found from the analysis of neutrino data. This number is in agreement with the expectation of 18.1±2.8 background events from standard neutrino processes. A new 90 % C.L. upper limit on the branching ratio Br ( π 0 → γ + X ) −5 for X masses ranging from 0 to 120 MeV/ c 2 is obtained.
117742578
Inclusive double-helicity asymmetries in neutral-pion and eta-meson production in $\vec{p}+\vec{p}$ collisions at $\sqrt{s}=200$ GeV
Results are presented from data recorded in 2009 by the PHENIX experiment at the Relativistic Heavy Ion Collider for the double-longitudinal spin asymmetry, $A_{LL}$, for $\pi^0$ and $\eta$ production in $\sqrt{s} = 200$ GeV polarized $p$$+$$p$ collisions. Comparison of the $\pi^0$ results with different theory expectations based on fits of other published data showed a preference for small positive values of gluon polarization, $\Delta G$, in the proton in the probed Bjorken $x$ range. The effect of adding the new 2009 \pz data to a recent global analysis of polarized scattering data is also shown, resulting in a best fit value $\Delta G^{[0.05,0.2]}_{\mbox{DSSV}} = 0.06^{+0.11}_{-0.15}$ in the range $0.05<x<0.2$, with the uncertainty at $\Delta \chi^2 = 9$ when considering only statistical experimental uncertainties. Shifting the PHENIX data points by their systematic uncertainty leads to a variation of the best-fit value of $\Delta G^{[0.05,0.2]}_{\mbox{DSSV}}$ between $0.02$ and $0.12$, demonstrating the need for full treatment of the experimental systematic uncertainties in future global analyses.