Search results for "Polar"
showing 10 items of 3817 documents
Quantum-chemical simulations of free and bound hole polarons in corundum crystal
1997
Abstract The semi-empirical method of the so-called intermediate neglect of differential overlap (INDO) has been applied to the calculations of the hole small-radius polarons in corundum crystals. Results for optimized atomic and electronic structure using two different approaches (the molecular cluster and periodic, supercell model) are critically compared. It is shown that the main results are similar in both cases.
Strong CP-violation in an effective chiral lagrangian approach
1991
21 páginas, 2 figuras.-- CERN-TH-6071-91
Hadron polarizability data analysis: GoAT
2015
The A2 Collaboration at the Institute for Nuclear Physics in Mainz, Germany, is working towards determining the polarizabilities of hadrons from nonperturbative quantum chromodynamics through Compton scattering experiments at low energies. The asymmetry observables are directly related to the scalar and spin polarizabilities of the hadrons. Online analysis software, which will give real-time feedback on asymmetries, efficiencies, energies, and angle distributions, has been developed. The new software is a big improvement over the existing online code and will greatly develop the quality of the acquired data.
Search forB0→ϕ(K+π−)decays with largeK+π−invariant mass
2007
Motivated by the polarization anomaly in the B→ (1020)K*(892) decay, we extend our search for other K* final states in the decay B0→ (1020)K*0 with the K*0→K+π- invariant mass above 1.6 GeV. The final states considered include the K*(1680)0, K3*(1780)0, K4*(2045)0, and a Kπ spin-zero nonresonant component. We also search for B0→ D0 decay with the same final state. The analysis is based on a sample of about 384×106 BB pairs recorded with the BABAR detector. We place upper limits on the branching fractions B(B0→ K*(1680)0)<3.5×10-6, B(B0→ K3*(1780)0) <2.7×10-6, B(B0→ K4*(2045)0)<15.3×10-6, and B(B0→ D0)<11.7×10-6 at 90% C.L. The nonresonant contribution is consistent with the measurements in …
The hadronic cross-section in the resonance energy region
2004
Abstract We study the hadronic vacuum polarization in the resonance energy region, using the framework given bythe Resonance Effective Theory of QCD. We consider the incorporation of vector-pseudoscalar meson loops that give, inclusively, three and four pseudoscalar meson cuts. After resummation we achieve a QCD-based inclusive parameterization of the correlator, hence of the hadronic cross-section in the energy region populated by resonances.
LOW-ENERGY QCD II — STATUS OF LATTICE CALCULATIONS
2013
The current status of lattice calculations is reviewed, with a particular emphasis on the question whether lattice simulations have matured to a stage where there is full interaction with experiment. Particular examples include the hadron spectrum, mesonic form factors and decay constants, the axial charge of the nucleon, and the hadronic vacuum polarization contribution to the muon (g-2).
Two-photon exchange in elastic electron-proton scattering: a QCD factorization approach.
2009
We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer $Q^2$. It is shown that the leading two-photon exchange amplitude behaves as $1/Q^4$ relative to the one-photon amplitude, and can be expressed in a model independent way in terms of the leading twist nucleon distribution amplitudes. Using several models for the nucleon distribution amplitudes, we provide estimates for existing data and for ongoing experiments.
Angular distribution of inclusive lepton pairs from heavy quarkonium decay
1983
We calculate polar and azimuthal angular distributions of inclusive lepton pairs in the decay $$Q\bar Q(1^{ - - } ) \to 1^ + 1^ - + X$$ from the first order QCD process $$Q\bar Q(1^{ - - } ) \to 1^ + 1^ - + gg$$ . We provide opening angle distributions of the lepton pair in order to assess the measurability of the lepton pairs.
Polarization and cross section of midrapidity J/ψ production in p+p collisions at s=510 GeV
2020
The PHENIX experiment has measured the spin alignment for inclusive J/ψ→e+e- decays in proton-proton collisions at s=510 GeV at midrapidity. The angular distributions have been measured in three different polarization frames, and the three decay angular coefficients have been extracted in a full two-dimensional analysis. Previously, PHENIX saw large longitudinal net polarization at forward rapidity at the same collision energy. This analysis at midrapidity, complementary to the previous PHENIX results, sees no sizable polarization in the measured transverse momentum range of 0.0
Duality in semileptonicτdecay
1984
The branching ratios for all channels of tau decay are reconsidered within the framework of perturbative and nonperturbative QCD. The predictions agree with experiment.