Search results for "Scattering length"
showing 10 items of 67 documents
Coulomb breakup of 23O
2005
Abstract The ground-state structure of the near-drip-line nucleus 23O has been investigated in a one-neutron Coulomb breakup reaction. Differential cross sections d σ / d E * for electromagnetic excitation of 23O projectiles (422 MeV/nucleon) incident on a lead target have been obtained from the measurement of the momenta of all breakup products including γ rays. The analysis of the deduced dipole-transition probability into the continuum infers a 2 s 1 / 2 ⊗ O 22 ( 0 + ) ground state configuration with a spectroscopic factor of 0.77(10) and thus a ground-state spin I π ( O 23 ) = 1 / 2 + , resolving earlier conflicting experimental findings. Final-state interaction is of significant influe…
ΛNNandΣNNsystems at threshold
2007
We calculate the hypertriton binding energy and the $\ensuremath{\Lambda}d$ and $\ensuremath{\Sigma}d$ scattering lengths using baryon-baryon interactions obtained from a chiral constituent quark model. We study consistently the $\ensuremath{\Lambda}\mathit{NN}$ and $\ensuremath{\Sigma}\mathit{NN}$ systems by analyzing the effect of the $\ensuremath{\Sigma}\ensuremath{\leftrightarrow}\ensuremath{\Lambda}$ conversion. Our interactions correctly predict the hypertriton binding energy. The $(I,J)=(0,3/2)$ $\ensuremath{\Lambda}\mathit{NN}$ channel is also attractive and it might have a bound state. From the condition of nonexistence of a (0,3/2) $\ensuremath{\Lambda}\mathit{NN}$ bound state, an…
Photoproduction of theωmeson on the proton near threshold
2015
An experimental study of omega photoproduction on the proton was conducted by using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. The gamma p -> omega p differential cross sections are measured from threshold to the incident-photon energy E-gamma = 1.40 GeV (W = 1.87 GeV for the center-of-mass energy) with 15-MeV binning in E-gamma and full production-angle coverage. The quality of the present data near threshold gives access to a variety of interesting physics aspects. As an example, an estimation of the omega N scattering length alpha(omega p) is provided.
Angular and polarization dependence of Compton scattering from in the Δ-resonance region
1998
Abstract Using linearly polarized tagged photons from coherent bremsstrahlung, differential cross sections and beam asymmetries for Compton scattering by 4 He have been measured at MAMI in the energy interval between 150 MeV and 500 MeV for scattering angles of θ γ lab =37°, 93° and 137°, thus largely increasing the available data base. Improved calculations in terms of the Δ -hole model completely fail to describe the data at large scattering angles. The same proved to be true for a schematic model, even after taking into account properties of nuclear photo-absorption in very detail.
Study of meson production in nuclei near threshold
2009
We present a study of the η production at low energies in pd collision with 3He and pd nuclear systems in the final state. The η production mechanism is described by a two-step model and the final state interactions are included fully. The η - d and η - 3He final state interactions are incorporated through the solution of the Lippmann Schwinger equation for a half off-shell η - AT-matrix. For η - d this t -matrix is written in a factorized form, with an off-shell form factor multiplying an on-shell part having the scattering length representation. The p - d final state interaction is included by multiplying the production matrix element by the inverse of the Jost function which includes th…
Study of internal structures of 9,10Be and 10B in scattering of 4He from 9Be
2013
A study of inelastic scattering and single-particle transfer reactions was performed by an alpha beam at 63 MeV on a 9$Be target. Angular distributions of the differential cross sections for the 9Be(4He,4He')9Be*, 9Be(4He,3He)10Be and 9Be(4He,t)10B reactions were measured. Experimental angular distributions of the differential cross sections for the ground state and a few low-lying states were analyzed in the framework of the optical model, coupled channels and distorted-wave Born approximation. An analysis of the obtained spectroscopic factors was performed.
ΛNNandΣNNsystems at threshold. II. The effect ofDwaves
2007
Using the two-body interactions obtained from a chiral constituent quark model, we study allN N andN N states with I = 0, 1, 2a ndJ = 1/2, 3/2 at threshold, taking into account all three-body configurations with S and D wave components. We constrain further the limits for theN spin-triplet scattering length a1/2,1 .U sing the hypertriton binding energy, we find a narrow interval for the possible values of theN spin-singlet scattering length a1/2,0. We find that theN N system has a quasibound state in the (I,J ) = (1, 1/2) channel very near threshold with a width of about 2.1 MeV.
EXTRACTION OF ΛΛ SCATTERING LENGTH
2009
We determine ΛΛ scattering parameters from a ΛΛ invariant mass spectrum that was obtained by 12 C (K-, K+ΛΛ) reaction at the KEK Proton Synchrotron. In the framework of Watson's procedure, the obtained scattering length [Formula: see text] and effective range [Formula: see text] are most consistent with the values predicted by using the Nijmegen soft core models (NSC97's). However, the predicted values by using the Nijmegen hard-core ND ( G -matrix) and the extended soft-core (ESC00) models are out of two standard deviations from the determined scattering parameters.
Dark Matter Bound States from Three-Body Recombination
2020
The small-scale structure problems of the universe can be solved by self-interacting dark matter that becomes strongly interacting at low energies. A particularly predictive model is resonant short-range self-interactions, with a dark-matter mass of about 19 GeV and a large S-wave scattering length of about 17 fm. Such a model makes definite predictions for the few-body physics of weakly bound clusters of the dark-matter particles. We calculate the production of two-body bound clusters by three-body recombination in the early universe under the assumption that the dark matter particles are identical bosons, which is the most favorable case for forming larger clusters. The fraction of dark m…
Accessing the real part of the forwardJ/ψ−pscattering amplitude fromJ/ψphotoproduction on protons around threshold
2016
We provide an updated analysis of the forward $J/\ensuremath{\psi}$-p scattering amplitude, relating its imaginary part to $\ensuremath{\gamma}p\ensuremath{\rightarrow}J/\ensuremath{\psi}p$ and $\ensuremath{\gamma}p\ensuremath{\rightarrow}c\overline{c}X$ cross section data, and calculating its real part through a once-subtracted dispersion relation. From a global fit to both differential and total cross section data, we extract a value for the spin-averaged $J/\ensuremath{\psi}$-p s-wave scattering length ${a}_{\ensuremath{\psi}p}=0.046\ifmmode\pm\else\textpm\fi{}0.005\text{ }\text{ }\mathrm{fm}$, which can be translated into a $J/\ensuremath{\psi}$ binding energy in nuclear matter of ${B}_…