Search results for "probability"
showing 10 items of 3417 documents
Constraints from $v_2$ fluctuations for the initial state geometry of heavy-ion collisions
2014
The ability to accurately compute the series of coefficients $v_n$ characterizing the momentum space anisotropies of particle production in ultrarelativistic heavy ion collisions as a function of centrality is widely regarded as a triumph of fluid dynamics as description of the bulk matter evolution. A key ingredient to fluid dynamical modeling is however the initial spatial distribution of matter as created by a yet not completely understood equilibration process. A measurement directly sensitive to this initial state geometry is therefore of high value for constraining models of pre-equilibrium dynamics. Recently, it has been shown that such a measurement is indeed possible in terms of th…
Evidence for prolate structure in light Pb isotopes from in-beamγ-ray spectroscopy ofPb185
2009
For the first time, excited states in {sup 185}Pb have been observed in in-beam {gamma}-ray spectroscopic measurements using the recoil-decay tagging method. The resulting level scheme reveals a strongly coupled yrast band structure that originates from coupling of the i{sub 13/2} quasineutron to a prolate deformed core. The band is also observed to de-excite via the spherical {alpha}-decaying 13/2{sup +}isomeric state.
The Role of Fission in the r-process
2007
We have developed a full set of fission rates that include spontaneous fission, neutron-induced fission, beta-delayed fission and, neutrino-induced fission, that are supplemented with realistic distributions of fission yields. Using this new input data we have carried out r-process calculations assuming adiabatic expansions that mimic the conditions achieved in the supernova neutrino driven wind. We have explored the sensitivity of the final abundances to different mass models. The resulting abundance distribution turns out to be very sensitive to the strength of the N = 82 shell gap far from stability. Mass models with a strong shell gap converge to an r-process distribution that is indepe…
Goodness-of-fit tests in many dimensions
2004
A method is presented to construct goodness-of-fit statistics in many dimensions for which the distribution of all possible test results in the limit of an infinite number of data becomes Gaussian if also the number of dimensions becomes infinite. Furthermore, an explicit example is presented, for which this distribution as good as only depends on the expectation value and the variance of the statistic for any dimension larger than one.
Triangle mechanism in τ → f1(1285)πντ decay
2018
Abstract We show that the τ − decay into f 1 ( 1285 ) π − ν τ is dominated by a triangle loop mechanism with K ⁎ , K ¯ ⁎ and K (or K ¯ ) as internal lines, which manifests a strong enhancement reminiscent of a nearby singularity present in the narrow K ⁎ limit and the near K ¯ ⁎ K ⁎ threshold of the internal K ⁎ propagators. The f 1 ( 1285 ) is then produced by its coupling to the K ⁎ K ¯ and K ¯ ⁎ K which is obtained from a previous model where this resonance was dynamically generated as a molecular K ⁎ K ¯ (or K ¯ ⁎ K ) state using the techniques of the chiral unitary approach. We make predictions for the f 1 π mass distribution which significantly deviates from the phase-space shape, due…
The role of f0(1710) in the ϕω threshold peak of J/Ψ→γϕω
2013
Abstract We study the process J / Ψ → γ ϕ ω , measured by the BES experiment, where a neat peak close to the ϕω threshold is observed and is associated to a scalar meson resonance around 1800 MeV. We make the observation that a scalar resonance coupling to ϕω unavoidably couples strongly to K K ¯ , but no trace of a peak is seen in the K K ¯ spectrum of the J / Ψ → γ K K ¯ at this energy. This serves us to rule out the interpretation of the observed peak as a signal of a new resonance. After this is done, a thorough study is performed on the production of a pair of vector mesons and how its interaction leads necessarily to a peak in the J / Ψ → γ ϕ ω reaction close to the ϕω threshold, due …
Second-forbidden nonunique $$\beta ^-$$ decays of $$^{59,60}$$Fe:possible candidates for $$g_{\mathrm{A}}$$ sensitive electron spectral-shape measure…
2021
In this work, we present a theoretical study of the electron spectral shapes for the second-forbidden nonunique $\beta^-$-decay transitions $^{59}\textrm{Fe}(3/2^-)\to\,^{59}\textrm{Co}(7/2^-)$ and $^{60}\textrm{Fe}(0^+)\to\,^{60}\textrm{Co}(2^+)$ in the framework of the nuclear shell model. We have computed the involved wave functions by carrying out a complete $0\hbar\omega$ calculation in the full $fp$ model space using the KB3G and GXPF1A effective interactions. When compared with the available data, these interactions predict the low-energy spectra and electromagnetic properties of the involved nuclei quite successfully. This success paves the way for the computations of the $\beta$-de…
Charged current weak production of the Delta resonance
1999
The charge changing weak production of Delta in nucleons and nuclei is studied. The reactions e^{-} p -> Delta^{0} ��_{e} and e^{+} p -> Delta^{++} \bar��_{e} are considered as a possible source of information about the weak N-Delta transition form factors. The low q^2 BNL data on neutrino production of Delta are used to extract the axial vector N-Delta coupling, taking into account the deuteron structure and the Delta width. Finally, pion production induced by neutrinos in ^{16}O in the Delta region, relevant to atmospheric neutrino experiments, is investigated.
Study of a possible S=+1 dynamically generated baryonic resonance
2005
Starting from the lowest order chiral Lagrangian for the interaction of the baryon decuplet with the octet of pseudoscalar mesons we find an attractive interaction in the $\Delta K$ channel with L=0 and I=1, while the interaction is repulsive for I=2. The attractive interaction leads to a pole in the second Riemann sheet of the complex plane and manifests itself in a large strength of the $\Delta K$ scattering amplitude close to the $\Delta K$ threshold, which is not the case for I=2. However, we also make a study of uncertainties in the model and conclude that the existence of this pole depends sensitively upon the input used and can disappear within reasonable variations of the input para…
Measurement of the ratio using event shape variables
1993
Abstract The branching fraction of Z → b b relative to all hadronic decays of the Z has been measured using event shape variables to preferentially select Z → b b events. The method chosen applies a combination of shape discriminators and the selection of high transverse momentum leptons to event hemispheres. From a sample of 440 000 hadronic Z decays collected with the ALEPH detector at LEP, the ration Γ b b Γ had = 0.228±0.005( stat. )±0.005( syst. ) is measured.