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Results for “LEPTON-LEPTON INTERACTIONS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Wave function multifractality and dephasing at metal-insulator and quantum Hall transitions

Research highlights: {yields}Dephasing rate due to short-range e-e interaction at Anderson transitions is analyzed. {yields}The operators controlling the scaling of the dephasing rate are idenitified. {yields}Dephasing rate exponent is estimated for the quantum Hall transition. - Abstract: We analyze the critical behavior of the dephasing rate induced by short-range electron-electron interaction near an Anderson transition of metal-insulator or quantum Hall type. The corresponding exponent characterizes the scaling of the transition width with temperature. Assuming no spin degeneracy, the critical behavior can be studied by performing the scaling analysis in the vicinity of the non-interacting fixed point, since the latter is stable with respect to the interaction. We combine an analytical treatment (that includes the identification of operators responsible for dephasing in the formalism of the non-linear sigma-model and the corresponding renormalization-group analysis in 2 + {epsilon} dimensions) with numerical simulations on the Chalker-Coddington network model of the quantum Hall transition. Finally, we discuss the current understanding of the Coulomb interaction case and the available experimental data.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2011

Light-meson properties from the Bethe-Salpeter equation

We discuss how to extract observables from an inhomogeneous vertex Bethe-Salpeter equation without resorting to the corresponding homogeneous equation. As an example we present a prediction for the e{sup +}e{sup -} decay width of the {rho}(1450) or {rho}{sup '} meson. We also attempt to identify the momentum range contributing to a vector meson's decay constant.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

DD-bar production and their interactions

We have explored the bound state problem and the scattering problem of the DD-bar pair in a meson exchange model. When considering their production in the e{sup +}e{sup -} process, we included the DD-bar rescattering effect. Although it is difficult to answer whether the S-wave DD-bar bound state exists or not from the binding energies and the phase shifts, one may get an upper limit of the binding energy from the production of the BB-bar, the bottom analog of DD-bar.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Anomalous Soft Photons associated with Hadron Production in String Fragmentation

The bosonized QCD2+QED2 system for quarks with two flavors contains QCD2 and QED2 bound states, with an isoscalar photon at about 25 MeV and an isovector (I = 1,I{sub 3} = 0) photon at about 44 MeV. Consequently, when a quark and an antiquark at the two ends of a string pulls apart from each other at high energies, hadrons and soft photons will be produced simultaneously in the fragmentation of the string. The production of the QED2 soft photons in association with hadrons may explain the anomalous soft photon data in hadron-hadron collisions and e{sup +}-e{sup -} annihilations at high energies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Inclusive J/{psi} production in proton-proton interactions at {radical}(s) = 7 TeV with ALICE at LHC

The ALICE experiment at the CERN's Large Hadron Collider allows the study of charmonium production in both e{sup +}e{sup -} and {mu}{sup +}{mu}{sup -} decay channels. In this paper, the first results obtained from reconstructing J/{psi} mesons in proton-proton interactions at {radical}(s) = 7 TeV are discussed. The present plans for quarkonia analyses are also mentioned.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

E6 Gamma Decay

Rare electric hexacontatetrapole (E6) transitions are studied in the full (f{sub 7/2},f{sub 5/2},p{sub 3/2},p{sub 1/2}) shell-model basis. Comparison of theory to the results from the gamma decay in {sup 53}Fe and from inelastic electron scattering on {sup 52}Cr provides unique and interesting tests of the valence wavefunctions, the models used for energy density functionals and into the origin of effective charge.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Oxygen-Atom Defects In 6H Silicon Carbide Implanted Using 24- MeV O{sup 3+} Ions Measured Using Three-Dimensional Positron Annihilation Spectroscopy System (3DPASS)

Three dimensional electron-positron (e{sup -}-e{sup +}) momentum distributions were measured for single crystal 6H silicon carbide (SiC); both virgin and having implanted oxygen-atom defects. 6H SiC samples were irradiated by 24- MeV O{sup 3+} ions at 20 particle-nanoamps at the Sandia National Laboratory's Ion Beam Facility. O{sup 3+} ions were implanted 10.8 {mu}m deep normal to the (0001) face of one side of the SiC samples. During positron annihilation measurements, the opposite face of the 254.0-{mu}m thick SiC samples was exposed to positrons from a {sup 22}Na source. This technique reduced the influence on the momentum measurements of vacancy-type defects resulting from knock-on damage by the O{sup 3+} ions. A three-dimensional positron annihilation spectroscopy system (3DPASS) was used to measure e{sup -}-e{sup +} momentum distributions for virgin and irradiated 6H SiC crystal both before and following annealing. 3DPASS simultaneously measures coincident Doppler-broadening (DBAR) and angular correlation of annihilation radiation (ACAR) spectra. DBAR ratio plots and 2D ACAR spectra are presented. Changes in the momentum anisotropies relative to crystal orientation observed in 2D ACAR spectra for annealed O-implanted SiC agree with the local structure of defect distortion predicted using Surface Integrated Molecular Orbital/Molecular Mechanics (SIMOMM). Oxygen atoms insert between Si and C atoms increasing their separation by 0.9 A forming a Si-O-C bond angle of {approx}150 deg.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2011

Experimental Results in DIS, SIDIS and DES from Jefferson Lab

Jefferson Lab's electron accelerator in its present incarnation, with a maximum beam energy slightly above 6 GeV, has already enabled a large number of experiments expanding our knowledge of nucleon and nuclear structure (especially in Deep Inelastic Scattering--DIS--at moderately high x, and in the resonance region). Several pioneering experiments have yielded first results on Deeply Virtual Compton Scattering (DVCS) and other Deep Exclusive Processes (DES), and the exploration of the rich landscape of transverse momentum-dependent (TMD) structure functions using Semi-Inclusive electron scattering (SIDIS) has begun. With the upgrade of CEBAF to 12 GeV now underway, a significantly larger kinematic space will become available. The 12 GeV program taking shape will complete a detailed mapping of inclusive, TMD and generalized distribution functions for quarks, antiquarks and gluons in the valence region and beyond.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Identification of Family Non-universal Gauge Bosons in High-energy Electron-positron Collisions

We examine effects on measurable observables in e{sup +}e{sup -} collisions resulting from the existence of additional neutral gauge bosons originating in extensions of the standard model. In particular, we consider family non-universal neutral gauge bosons occurring in the minimal supersymmetric standard model and in the Sp(6){sub L} x U(1){sub Y} model, as well as other theoretically motivated popular neutral gauge bosons. We show how the proper employment of the generation-dependent couplings of the extra gauge boson, and the appropriate adjustment of the beam polarization, not only improved the identification of the models but also enhanced the discovery potential of the family non-universal extra gauge bosons.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Tau contributions to muon/electron events at a neutrino factory

The oscillation of the muon and electron neutrinos (anti-neutrinos) to tau neutrinos (anti-neutrinos) adds to the muon and electron events sample (both right sign and wrong sign) via leptonic decays of the taus produced through charge current interactions in the detector. We focus on how this contribution affects a precision measurement of the atmospheric mixing parameters and the deviation of v{sub {mu}} {r_reversible} v{sub {tau}} mixing from maximality. We also comment on the tau contamination in the golden and platinum channels.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Using near detector data to make far detector predictions in an on-axis long-baseline experiment

Various techniques have been developed in long-baseline neutrino oscillation experiments to leverage near detector data to form predictions for the far detector spectrum and backgrounds. I will review the techniques used in MINOS, an on-axis long-b aseline neutrino experiment that uses Fermilab's NuMI beam. The extrapolation methods used in the MINOS muon neutrino and anti-neutrino disappearance measurements and electron neutrino appearance search will be covered.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

IDR Muon Capture Front End and Variations

The (International Design Report) IDR neutrino factory scenario for capture, bunching, phase-energy rotation and initial cooling of {mu}'s produced from a proton source target is explored. It requires a drift section from the target, a bunching section and a {phi}-{delta}E rotation section leading into the cooling channel. The rf frequency changes along the bunching and rotation transport in order to form the 's into a train of equal-energy bunches suitable for cooling and acceleration. Optimization and variations are discussed. An important concern is rf limitations within the focusing magnetic fields; mitigation procedures are described. The method can be extended to provide muons for a {mu}{sup +}-{mu}{sup -} Collider; variations toward optimizing that extension are discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Physics with KLOE and KLOE-2 Experiments at DA{Phi}NE

The KLOE experiment has collected 2.5 fb{sup -1} of e{sup +}e{sup -} collisions at the {phi} peak and about 250 pb{sup -1} in the center of mass energy 1 GeV. Data taken on peak are used to study properties of light scalar and pseudoscalar mesons, produced through {phi} radiative decays. Off-peak data are used to perform preliminary analyses of the reactions e{sup +}e{sup -} {yields} e{sup +}e{sup -}{pi}{sup 0}{pi}{sup 0} and e{sup +}e{sup -}{yields} e{sup +}e{sup -}{eta}. All these studies will be extended with the coming KLOE-2 run.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Results on Charmonium(-like) and Bottomonium(-like) States from Belle and BaBar

Spectroscopy results for Belle and BaBar are reported. A particular focus is put on new results of the X(3872) state with its radiative decays to J/{psi}{gamma} and {psi}'{gamma} its decay into J/{psi}3{pi} and the search for production in radiative Upsilon decays. Another focus is L = 2 mesons, in particlar a possible D-wave assignment to the X(3872) and the confirmation of an Upsilon D-wave state.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Precision spectroscopy of light kaonic atom X-rays in the SIDDHARTA experiment

The KN system at rest makes a sensitive testing ground for low energy QCD. At the DA{Phi}NE electron-positron collider of Laboratori Nazionali di Frascati we study kaonic atoms, taking advantage of the low-energy kaons from {Phi}-mesons decaying nearly at rest. The DEAR (DA{Phi}NE Exotic Atom Research) experiment at LNF delivered the most precise data on kaonic hydrogen up to now. DEAR and its follow-up experiment SIDDHARTA (Silicon Drift Detector for Hadronic Atom Research by Timing Application) are using X-ray spectroscopy of kaonic atoms to measure the strong interaction induced shift and width of the ground state. SIDDHARTA is the first experiment on kaonic helium-3 and deuterium ever, and kaonic hydrogen was remeasured with improved precision.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Charm Baryon Results from BaBar

We present experimental results from the BaBar experiment on charm baryon spectroscopy and production studies, including studies of excited cascades produced in charm baryon decays. We review the discovery of new decay modes of known states and searches for predicted states.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Studies of antikaon interactions with nucleons at DA{Phi}NE

AMADEUS is an experiment planned to be performed at the DAFNE e{sup +}e{sup -} collider of the Frascati National Laboratories (Italy) of INFN, to investigate the antikaon-nuclei interaction at low energies. AMADEUS will perform, for the first time, full-acceptance studies of antikaon interaction in light nuclei, including a complete experimental program for the case of the kaonic clusters. The study of the absorption of antikaon by the nucleus will provide information concerning the K-barN interaction and the modification of the kaon mass in the nuclear medium.The experiment is being preceded by the study of the hadronic interactions of K{sup -} in the {sup 4}He of the drift chamber from the KLOE experiment data.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗