Search results for "EXPA"
showing 10 items of 820 documents
GW190412: Observation of a binary-black-hole coalescence with asymmetric masses
2020
LIGO Scientific Collaboration and Virgo Collaboration: et al.
Efficient numerical integration of neutrino oscillations in matter
2016
A special purpose solver, based on the Magnus expansion, well suited for the integration of the linear three neutrino oscillations equations in matter is proposed. The computations are speeded up to two orders of magnitude with respect to a general numerical integrator, a fact that could smooth the way for massive numerical integration concomitant with experimental data analyses. Detailed illustrations about numerical procedure and computer time costs are provided.
Study of Even Gd Nuclei by Decay of Oriented Tb, With Analysis by Simple Boson Models
1983
We have studied low-spin states of 150,152,154,156Gd by nuclear orientation of β-decaying Tb in a Gd host. Especially by means of multipole mixing ratios, including E0/E2, we have checked and revised spin-parities and assignments to (quasi) rotational ground, β and γ bands. For 150Gd we propose the new interpretation 1207.2 keV (0β+), 1518.5 keV (2β+), 1700.1 keV (4β+), 1430.5 keV (2γ+), 1988.0 keV (3γ+), 2080.0 keV (4γ+). For 152,154,156Gd we find agreement with recent literature. Our comparison with theory includes available data on 158,160Gd and on states up to 10g+, 10β+, 7γ+. We review our previously proposed "projection model", which is basically of the Bohr-Mottelson geometrical type…
Updated determination of chiral couplings and vacuum condensates from hadronic tau decay data
2016
We analyze the lowest spectral moments of the left-right two-point correlation function, using all known short-distance constraints and the recently updated ALEPH V-A spectral function from tau decays. This information is used to determine the low-energy couplings L10 and C87 of chiral perturbation theory and the lowest-dimensional contributions to the Operator Product Expansion of the left-right correlator. A detailed statistical analysis is implemented to assess the theoretical uncertainties, including violations of quark-hadron duality.
Implications of tau data for CP violation in K decays
2019
The \bm{D=6}𝐃=6 contribution of the Operator Product Expansion (OPE) of the \bm{\mathrm{VV-AA}}VV−AA correlator of quark currents can be related to hadronic matrix elements associated to CP violation in non-leptonic kaon decays. We use those relations to find an updated value for \bm{\langle(\pi\pi)_{I=2}|\mathcal{Q}_{8}|K\rangle}⟨(𝛑𝛑)𝐈=2|𝒬8|𝐊⟩ in the chiral limit using the updated ALEPH spectral function. Taking instead values of the matrix elements from the lattice to obtain the \bm{D=6}𝐃=6 vacuum elements provides a new short-distance constraint that allows for an inclusive determination of \bm{f_{\pi}}𝐟𝛑 and an updated value for the \bm{D=8}𝐃=8 condensate.
Measurement of higher-order multipole amplitudes in ψ(3686)→γχc1,2 with χc1,2→γJ/ψ and search for the transition ηc(2S)→γJ/ψ
2017
Using 106 x 10(6) psi(3686) events collected with the BESIII detector, we measure multipole amplitudes for the decay psi(3686) ->; gamma chi(c1,2) -> gamma gamma J/psi beyond the dominant electric-dipole amplitudes. The normalized magnetic-quadrupole (M2) amplitude for psi(3686) -> gamma chi(c1,2) -> gamma gamma J/psi and the normalized electric-dipole amplitudes for psi(3686) -> gamma chi(c2) -> gamma J/psi and determined. The M2 amplitudes for psi(3686) -> gamma chi(c1) and ; chi(c1,2) -> gamma J/psi are found to differ significantly from zero and are consistent with theoretical predictions. We also obtain the ratios of M2 contributions of psi(3686) and J/psi decays to;2,chi(c1,2,) b(2)(1…
Model Dependence of Nucleon Resonance Parameters
2004
Nucleon resonance parameters as mass, width, branching ratios and electromagnetic helicity amplitudes cannot be determined in a model independent way. The best way to obtain such elementary quantities is in terms of a partial wave analysis and a separation of resonance and background. In this work we have concentrated on the extraction of the e.m. helicity amplitudes A l p and A312 from electric and magnetic multipole analyses that were obtained from different groups with different techniques. We make a comparison of our results for the resonances P11(1440), 013(1520) and s11(1535). The variation that we find can be considered as a measure of the model uncertainty in these quantities.
Formal theory for two-particle channels
1991
The general formalism has been developed over many years by various authors. One starting point is the work of de Swart (DSw 59) who has considered electric multipoles in the long-wave-length limit using the Siegert theorem and as magnetic contribution only the dipole spin-flip transition. The T-matrix is then expanded in terms of reduced multipole amplitudes. This approach has been generalized by Donnachie (Don 62a) and Partovi (Par 64) by including higher electric and magnetic multipoles. Furthermore, the electric multipoles are not restricted to the long-wave-length limit and the additional terms besides the Siegert operators (see section 4.1) are included. Using techniques from angular …
Solution of the Skyrme–Hartree–Fock–Bogolyubov equations in the Cartesian deformed harmonic-oscillator basis.
2012
We describe the new version (v2.38j) of the code hfodd which solves the nuclear SkyrmeHartree-Fock or Skyrme-Hartree-Fock-Bogolyubov problem by using the Cartesian deformed harmonic-oscillator basis. In the new version, we have implemented: (i) projection on good angular momentum (for the Hartree-Fock states), (ii) calculation of the GCM kernels, (iii) calculation of matrix elements of the Yukawa interaction, (iv) the BCS solutions for statedependent pairing gaps, (v) the HFB solutions for broken simplex symmetry, (vi) calculation of Bohr deformation parameters, (vii) constraints on the Schiff moments and scalar multipole moments, (viii) the D T transformations and rotations of wave functio…
The distribution of galaxies gravitational field stemming from their tidal interaction
2015
We calculate the distribution function of astronomical objects (like galaxies and/or smooth halos of different kinds) gravitational fields due to their tidal in- teraction. For that we apply the statistical method of Chandrasekhar (1943), used there to calculate famous Holtzmark distribution. We show that in our approach the distribution function is never Gaussian, its form being dictated by the potential of interaction between objects. This calculation permits us to perform a theoretical analysis of the relation between angular momentum and mass (richness) of the galaxy clusters. To do so, we follow the idea of Catelan & Theuns (1996) and Heavens & Peacock (1988). The main differen…