Search results for "approximation"
showing 10 items of 818 documents
Electron capture decay of116Inand nuclear structure of doubleβdecays
1998
Quasiparticle-random-phase-approximation (QRPA) calculations of double $\ensuremath{\beta}$ decays have not been able to reproduce data in the $A=100$ system. We propose the $A=116$ system---because of its smaller deformation---as a simpler system to test QRPA calculations. We present results of two experiments we performed, which determine the electron-capture-decay branch of ${}^{116}\mathrm{In}$ to be $(2.27\ifmmode\pm\else\textpm\fi{}0.63)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}%$, from which we deduce $\mathrm{log}{ft=4.39}_{\ensuremath{-}0.15}^{+0.10}$. We present QRPA calculations and compare their predictions to experimental data. Finally we use these calculations to…
Double beta decay versus cosmology: Majorana CP phases and nuclear matrix elements
2004
We discuss the relation between the absolute neutrino mass scale, the effective mass measured in neutrinoless double beta decay, and the Majorana CP phases. Emphasis is placed on estimating the upper bound on the nuclear matrix element entering calculations of the double beta decay half life. Consequently, one of the Majorana CP phases can be constrained when combining the claimed evidence for neutrinoless double beta decay with the neutrino mass bound from cosmology.
Total and inelastic cross sections at LHC ats=7 TeVand beyond
2011
We discuss expectations for the total and inelastic cross sections at LHC CM energies $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$ and 14 TeV obtained in an eikonal minijet model augmented by soft gluon ${k}_{t}$-resummation, which we describe in some detail. We present a band of predictions which encompass recent LHC data and suggest that the inelastic cross section described by two-channel eikonal models include only uncorrelated processes. We show that this interpretation of the model is supported by the LHC data.
Magnetic dipole moment of theΔ+(1232)from theγp→γπ0preaction
2001
The $\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{p}\ensuremath{\gamma}{\ensuremath{\pi}}^{0}p$ reaction in the $\ensuremath{\Delta}(1232)$-resonance region is investigated as a method to access the ${\ensuremath{\Delta}}^{+}(1232)$ magnetic dipole moment. The calculations are performed within the context of an effective Lagrangian model containing both the $\ensuremath{\Delta}$-resonant mechanism and a background of nonresonant contributions to the $\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{p}\ensuremath{\gamma}{\ensuremath{\pi}}^{0}p$ reaction. Results are shown both for existing and forthcoming $\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{p}\ensuremath{\…
Systematic study of neutrinoless double beta decay to excited 0+ states
2003
Abstract A systematic study of neutrinoless double beta (0 νββ ) decay to excited 0 + states, described as monopole-vibrational states or as composed of two collective quadrupole-phonon states, has been performed. Both double β − and double β + /EC decays have been analyzed within the framework of the multiple commutator model (MCM) by using a realistic nuclear many-body Hamiltonian and realistic mean-field single-particle bases. It is found that the associated 0 νββ -decay transitions are suppressed relative to the decay to the final ground state both by the available phase space and especially by the smallness of the involved transition matrix elements. For completeness, also the double β…
Observation of ${{e^+e^- \rightarrow D_s^+} \overline{ D}^{\bf (*)0} {K^-}}$ and study of the P -wave ${{D_s}}$ mesons
2018
Studies of $e^+e^- \to D_s^+ \overline{D}{}^{(*)0}K^-$ and the $P$-wave charmed-strange mesons are performed based on an $e^+e^-$ collision data sample corresponding to an integrated luminosity of 567 pb$^{-1}$ collected with the BESIII detector at $\sqrt{s}= 4.600$ GeV. The processes of $e^+e^-\to D_s^+ \overline{D}{*}^{0} K^-$ and $D_s^+ \overline{D}{}^{0} K^-$ are observed for the first time and are found to be dominated by the modes $D_s^+ D_{s1}(2536)^-$ and $D_s^+ D^*_{s2}(2573)^-$, respectively. The Born cross sections are measured to be $\sigma^{B}(e^+e^-\to D_s^+ \overline{D}{*}^{0} K^-) = (10.1\pm2.3\pm0.8) pb$ and $\sigma^{B}(e^+e^-\to D_s^+ \overline{D}{}^{0} K^-) = (19.4\pm2.3\…
Neutrino-nucleon scattering rate in proto-neutron star matter
2002
We present a calculation of the neutrino-nucleon scattering cross-section which takes into account the nuclear correlations in the relativistic random phase approximation (RPA). Our approach is based on a quantum-hadrodynamics model with exchange of sigma, omega, pi, rho and delta mesons. In view of applications to neutrino transport in the final stages of supornova explosion and proto-neutron star cooling, we study the evolution of the neutrino mean free path as a function of density, proton-noutron asymmetry and temperature. Special attention was paid to the issues of renormalization of the Dirac sea, residual interactions in the tensor channel, coupling to the delta-meson and meson mixin…
Inclusive and exclusive neutrino-nucleus cross sections and the reconstruction of the interaction kinematics
2021
Abstract We present a full kinematic analysis of neutrino-nucleus charged current quasielastic interactions based on the Local Fermi Gas model and the Random Phase Approximation. The model was implemented in the NEUT Monte Carlo framework, which allows us to investigate potentially measurable observables, including hadron distributions. We compare the predictions simultaneously to the most recent T2K and MINERvA charged current (CC) inclusive, CC0π and transverse kinematic-imbalance variable results. We pursuit a microscopic interpretation of the relevant reaction mechanisms, with the aim to achieving in neutrino oscillation experiments a correct reconstruction of the incoming neutrino kine…
Nuclear cross sections in 16O for β beam neutrinos at intermediate energies
2006
The nuclear cross sections for charged lepton production induced by $\beta$ beam neutrinos (anti-neutrinos) in $^{16}$O have been presented at intermediate energies corresponding to the Lorentz boost factor $\gamma<250 (150)$. The calculations for quasi-elastic lepton production includes the effect of Pauli blocking, Fermi motion and renormalization of weak transition strengths in the nuclear medium. The calculations for the inelastic lepton production is done in the $\Delta$ dominance model. The renormalization of $\Delta$ properties in a nuclear medium and final state interactions of pions with the final nucleus are taken into account. The results may be useful in performing feasibility s…
Comparing non-perturbative models of the breakup of neutron-halo nuclei
2012
Breakup reactions of loosely-bound nuclei are often used to extract structure and/or astrophysical information. Here we compare three non-perturbative reaction theories often used when analyzing breakup experiments, namely the continuum discretized coupled channel model, the time-dependent approach relying on a semiclassical approximation, and the dynamical eikonal approximation. Our test case consists of the breakup of 15C on Pb at 68 MeV/nucleon and 20 MeV/nucleon.