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Results for “PIONS MINUS”

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 OSTI2010

Analysis techniques for the {Lambda}(1405) in p+p reactions

We present an analysis of the {Lambda}(1405){yields}{Sigma}{sup {+-}}{pi}{sup {+-}} decay in p+p reactions at 3.5 GeV kinetic beam energy. The data were taken with the High Acceptance Di-Electron Spectrometer (HADES). The extraction of the {Lambda}(1405) signal was achieved by an effective background suppression combined with a quantitatively precise determination and identification of the remaining background sources. The different techniques, used for this analysis, are presented in this work.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Recent Results on Light Hadron Spectroscopy at BESIII

Using about 226x10{sup 6} J/{psi} events and 106x10{sup 6} {psi}{sup '} events accumulated with BESIII detector operating at BEPCII e{sup +}e{sup -} collider, the existence of pp-bar mass threshold enhancement and X(1835) is confirmed. Two new resonances, X(2120) and X(2370) are also observed in J/{psi}{yields}{gamma}{eta}{sup '}{pi}{sup +}{pi}{sup -}. In the analysis of J/{psi}{yields}{omega}{eta}{pi}{sup +}{pi}{sup -}, a new process J/{psi}{yields}{omega}X(1870){yields}{omega}a{sub 0}(980){pi} is seen with a significance of 7.7{sigma}. In addition, a direct measurement of f{sub 0}(980){yields}a{sub 0}{sup 0}(980) and a{sub 0}{sup 0}(980){yields}f{sub 0}(980) mixing transitions is presented to probe the properties of these two scalar states.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Transition nucleon resonance electrocouplings from CLAS data on {pi}{sup +}{pi}{sup -}p electroproduction off protons

Electrocouplings of excited proton states with masses less than 1.8 GeV were determined for the first time from the CLAS data on {pi}{sup +}{pi}{sup -}p electroproduction at photon virtualities Q{sup 2}<1.5 GeV{sup 2}. Electrocouplings were obtained from a combined fit of all available observables within the framework of a phenomenological reaction model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Photoproduction of {pi}{pi} Pairs off {sup 7}Li

This paper reports on the quasi-free photoproduction of {pi}{sup 0}{pi}{sup 0} and {pi}{sup 0}{pi}{sup +/-} pairs from {sup 7}Li in view of the in-medium properties of hadrons. Measurements have been done using the CB/TAPS detector setup and the Glasgow photon tagging spectrometer for incident photon energies up to 820 MeV. At small invariant masses, an enhancement of the neutral invariant mass distributions is seen compared to the mixed charged channel and could be explained either by an in-medium modification of the {pi}{pi} interaction in the I = J = 0 channel or by effects related to the final state interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

The Hyperon {Lambda}(1405) in p+p reactions

We present an analysis of the hyperon {Lambda}(1405) for p+p reactions at 3.5 GeV kinetic beam energy. The data were taken with the High Acceptance Di-Electron Spectrometer (HADES). A {Lambda}(1405) signal could be reconstructed in both charged decay channels ({Lambda}(1405){yields}{Sigma}{sup {+-}}{pi}{sup {+-}}).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Extraction of pion non-perturbative fragmentation functions in ZM-VFNS

We present pion non-perturbative fragmentation functions (non-pFFs) at next-to-leading order (NLO) obtained through a global fit to electron-positron annihilation data from CERN LEP1, SLAC SLC, DESY and KEK, using zero-mass variable-flavor-number scheme. We apply the obtained non-pFFs to predict the scaled-energy distribution of {pi}{sup {+-}} inclusively produced in top-quark decays. The results are in good agreement with the available theoretical models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Interpreting the peak structures around 1800 MeV in the BES data on J/Ψ→φπ{sup +}π{sup −}, J/Ψ→γωφ

In this talk we present an interpretation for the experimental data available on two different processes, namely, J/Ψ→φπ{sup +}π{sup −}, J/Ψ→γωφ, which seem to indicate existence of two new resonances with the same quantum numbers (J{sup πc} = 0{sup ++}, I = 0) and savery similar mass (1800 MeV) but with very different decay properties. However, our studies show that the peak structure found in the ωφ invariant mass, in J/Ψ→γωφ, is a manifestation of the well known f{sub 0}(1710) while the cross section enhancement found in J/Ψ→φπ{sup +}π{sup −} is indeed a new f{sub 0} resonance with mass near 1800 MeV. We present an explanation for the different decay properties of these two scalar resonances.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

STAR results on central exclusive production in proton-proton collisions

We present a preliminary measurement of the Central Exclusive Production of the two oppositely charged pions produced in the process pp → ppπ{sup +} π{sup −}, obtained with the STAR detector at RHIC at √(s)=200 GeV. Silicon strip detectors placed in Roman Pots were used for tagging forward protons while pion pair tracks were reconstructed in the STAR Time Projection Chamber. Predictions of models based on Regge phenomenology are compared to the spectra of the kinematical variables corrected for detector acceptance and efficiency.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Central exclusive π{sup +}π{sup −} production in pp{sup ¯} collisions at √(s)=0.9 and 1.96 TeV at CDF

Exclusive π{sup +}π{sup −} production in proton-antiproton collisions at √(s)=0.9 and 1.96 TeV in the Collider Detector at Fermilab has been measured. Events with exactly two particles with opposite charge, in |η(π)| < 1.3, with no other particles detected in |η(π)| < 5.9, were selected. We require the central π{sup +}π{sup −} state to have rapidity |y(ππ)| < 1. The data are expected to be dominated by double pomeron exchange. Therefore, the quantum numbers of the central state are constrained. The data show resonance structures attributed to the f{sub 0} and f{sub 2} mesons. The results are valuable for light hadron spectroscopy, and for understanding the nature of the pomeron in a region between non-perturbative and perturbative QCD.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Muon neutrino charged current inclusive charged pion (CCπ{sup ±}) production in MINERνA

The production of charged pions by neutrinos interacting on nuclei is of great interest in nuclear physics and neutrino oscillation experiments. The MINERνA experiment is working towards releasing the world’s first high statistics neutrino pion production measurements in a few-GeV neutrino beam. We describe MINERνA’s CCπ{sup ±} analysis event selection in both the neutrino and antineutrino beams, noting reconstruction resolutions and kinematic limits. We also show area-normalized data-simulation comparisons of the reconstructed muon and charged pion kinetic energy distributions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Measurements of pion production in eA with the CLAS detector

Preliminary results on semi-inclusive charged pion production in eA collisions at E{sub beam}=5 GeV/c{sup 2} are presented. The data were collected using the CLAS detector, which is a multipurpose, large acceptance, magnetic spectrometer located in Hall B at the Thomas Jefferson National Accelerator Facility. Selected distributions in W, Q{sup 2}, p{sub π}, and θ{sub π} are shown for data produced using deuterium, carbon, iron and lead targets. Preliminary comparisons with data simulated using the GENIE generator are made. The motivation for this work is to provide distributions useful for tuning the hadronic final state interaction models in order to reduce uncertainties in the results extracted from current and next-generation neutrino oscillation experiments.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Rigorous pion electromagnetic form factor behavior in the spacelike region

Precise experimental information on {sigma}{sub tot}(e{sup +}e{sup -}{yields}{pi}{sup +}{pi}{sup -}) is transferred into the spacelike region by taking advantage of the analyticity. As a result, rigorous pion electromagnetic form factor behavior in spacelike region is obtained. The latter is compared with some existing model predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Nuclear symmetry energy and proton-rich reactions at intermediate energies

Based on an isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, effects of high-density behavior of nuclear symmetry energy in the proton-rich reaction {sup 22}Si+{sup 22}Si at a beam energy of 400 MeV/nucleon are studied. It is found that the symmetry energy affects {pi}{sup +} production more than {pi}{sup -}. More interestingly, compared to neutron-rich reactions, for {pi}{sup -}/{pi}{sup +} and dense matter's N/Z ratios, effects of symmetry energy in the proton-rich reaction show contrary behaviors. The practical experiment by using the proton-rich reaction {sup 22}Si+{sup 40}Ca to study nuclear symmetry energy is also provided.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Momentum dependence of the symmetry potential and its influence on nuclear reactions

A Skyrme-type momentum-dependent nucleon-nucleon force distinguishing isospin effect is parametrized and further implemented in the Lanzhou quantum molecular dynamics model, which leads to a splitting of nucleon effective mass in nuclear matter. Based on the isospin- and momentum-dependent transport model, we investigate the influence of momentum-dependent symmetry potential on several isospin-sensitive observables in heavy-ion collisions. It is found that symmetry potentials with and without the momentum dependence but corresponding to the same density dependence of the symmetry energy result in different distributions of the observables. The midrapidity neutron/proton ratios at high transverse momenta and the excitation functions of the total {pi}{sup -}/{pi}{sup +} and K{sup 0}/K{sup +} yields are particularly sensitive to the momentum dependence of the symmetry potential.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Initialization effect in heavy-ion collisions at intermediate energies

Based on the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model plus the Skyrme force parameters, the initialization effect is studied in heavy-ion collisions at intermediate energies. We find that there are moderate initialization effects in the following observables: free neutron to proton ratio (n/p), {pi}{sup -}/{pi}{sup +} ratio, and neutron to proton differential flow (F{sub n-p}{sup x}). Effects of initialization are larger for charged {pi}{sup -}/{pi}{sup +} ratios than for n/p ratios. And the effects of initialization are more evident in nuclear reactions at lower incident beam energies. We do not see large effects of initialization for light reaction systems or large asymmetric (neutron-richer) reaction systems. We also see relatively large effects of initialization on the neutron to proton differential flow at relatively lower incident beam energies or with large impact parameters. These results may be useful for the delicate studies of the equation of state of asymmetric nuclear matter.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗