Search results for "scattering length"
showing 10 items of 67 documents
Production of dark-matter bound states in the early universe by three-body recombination
2018
The small-scale structure problems of the universe can be solved by self-interacting dark matter that becomes strongly interacting at low energy. A particularly predictive model for the self-interactions is resonant short-range interactions with an S-wave scattering length that is much larger than the range. The velocity dependence of the cross section in such a model provides an excellent fit to self-interaction cross sections inferred from dark-matter halos of galaxies and clusters of galaxies if the dark-matter mass is about 19 GeV and the scattering length is about 17 fm. Such a model makes definite predictions for the few-body physics of weakly bound clusters of the dark-matter particl…
Chiral unitary approach to eta'N scattering at low energies
2010
We study the \eta' N interaction within a chiral unitary approach which includes \pi N, \eta N and related pseudoscalar meson-baryon coupled channels. Since the SU(3) singlet does not contribute to the standard interaction and the \eta' is mostly a singlet, the resulting scattering amplitude is very small and inconsistent with experimental estimations of the \eta' N scattering length. The additional consideration of vector meson-baryon states into the coupled channel scheme, via normal and anomalous couplings of pseudoscalar to vector mesons, enhances substantially the \eta' N amplitude. We also exploit the freedom of adding to the Lagrangian a new term, allowed by the symmetries of QCD, wh…
Determination of the S-wave pion nucleon scattering lengths from πN, pionic hydrogen and deuteron
2005
The isoscalar and isovector scattering lengths ( b 0 , b 1 ) are determined using a unitarized coupled channel approach based on chiral Lagrangians. For the deuterium scattering length a π − d new significant corrections are evaluated, putting new constraints from π − d scattering on the values of ( b 0 , b 1 ) .
Proton-Deuteron Elastic Scattering for E > 0
1999
We report on the first reliable numerical results for proton-deuteron elastic scattering observables for energies above the deuteron breakup thresh- old, for the Paris potential. The calculations have been performed within the screening and renormalisation approach. The theoretical results are compared with recent experimental data.
The πd scattering length from Kα X-rays
1974
Abstract X-rays from the K α transition (2P → 1S) of the π − d mesic atom have been observed. Their energy, 2592.8 −2.0 +1.6 , has been measured by the critical absorber technique, using the M V absorption edge in bismuth. The strong interaction shift in the 1S state is −4.8 eV, corresponding to a scattering length a ( π d) = −(0.052 −0.017 +0.022 ) m π −1 , in agreement with recent calculations. The intensity ratio K α /K total = 0.548 ± 0.015.
Time calibration of the ANTARES neutrino telescope
2011
The ANTARES deep-sea neutrino telescope comprises a three-dimensional array of photomultipliers to detect the Cherenkov light induced by upgoing relativistic charged particles originating from neutrino interactions in the vicinity of the detector. The large scattering length of light in the deep sea facilitates an angular resolution of a few tenths of a degree for neutrino energies exceeding 10 TeV. In order to achieve this optimal performance, the time calibration procedures should ensure a relative time calibration between the photomultipliers at the level of ~1 ns. The methods developed to attain this level of precision are described.
Transmission of light in deep sea water at the site of the Antares neutrino telescope
2005
The ANTARES neutrino telescope is a large photomultiplier array designed to detect neutrino-induced upward-going muons by their Cherenkov radiation. Understanding the absorption and scattering of light in the deep Mediterranean is fundamental to optimising the design and performance of the detector. This paper presents measurements of blue and UV light transmission at the ANTARES site taken between 1997 and 2000. The derived values for the scattering length and the angular distribution of particulate scattering were found to be highly correlated, and results are therefore presented in terms of an absorption length lambda_abs and an effective scattering length lambda_sct^eff. The values for …
Two-photon exchange corrections to elastic e− -proton scattering: Full dispersive treatment of πN states at low momentum transfers
2017
We evaluate the pion-nucleon intermediate-state contribution to the two-photon exchange (TPE) correction in the elastic electron-nucleon scattering within a dispersive framework. We calculate the contribution from all $\ensuremath{\pi}N$ partial waves using the MAID parametrization. We provide the corresponding TPE correction to the unpolarized $ep$ scattering cross section in the region of low momentum transfer ${Q}^{2}\ensuremath{\lesssim}0.064\text{ }\text{ }{\mathrm{GeV}}^{2}$, where no analytical continuation into the unphysical region of the TPE scattering amplitudes is required. We compare our result in the forward angular region with an alternative TPE calculation, in terms of struc…
Coherence and clock shifts in ultracold fermi gases with resonant interactions.
2007
Using arguments based on sum rules, we derive a general result for the average shifts of rf lines in Fermi gases in terms of interatomic interaction strengths and two-particle correlation functions. We show that near an interaction resonance shifts vary inversely with the atomic scattering length, rather than linearly as in dilute gases, thus accounting for the experimental observation that clock shifts remain finite at Feshbach resonances.
Robust non-Markovianity in ultracold gases
2012
We study the effect of thermal fluctuations on a probe qubit interacting with a Bose-Einstein condensed (BEC) reservoir. The zero-temperature case was studied in [Haikka P et al 2011 Phys. Rev. A 84 031602], where we proposed a method to probe the effects of dimensionality and scattering length of a BEC based on its behavior as an environment. Here we show that the sensitivity of the probe qubit is remarkably robust against thermal noise. We give an intuitive explanation for the thermal resilience, showing that it is due to the unique choice of the probe qubit architecture of our model.