Search results for "Matrix"

Towards high-precision mass measurements on 74Rb for a test of the CVC hypothesis and the unitarity of the CKM matrix

2004

At the highest possible precisions, atomic-mass measurements can be used to perform fundamental studies. Examples for such studies are a check of the conserved-vector-current (CVC) hypothesis and the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, both postulates of the Standard Model. The comparative half-lives Ft of superallowed β decays constitute the nuclear-physics access to these tests. The Q value of the β decay of 74 Rb, one of the three experimentally accessible parameters that enter into the Ft values, has been measured with the ISOLTRAP experiment at ISOLDE/CERN. The ultimate mass precision requirement and the way to achieve it are outlined.

Review of the properties of the 0νβ−β−nuclear matrix elements

2012

In this work we investigate general properties of the nuclear matrix elements (NMEs) related to the neutrinoless double ?? decays (0????? decays) of several nuclei of interest for double-beta-decay experiments. A summary of the values of the NMEs calculated along the years by the Jyv?skyl??La Plata collaboration is given. These NMEs are compared with those of the other available calculations and general conclusions are drawn based on these comparisons.

NA48/62 latest results

2017

The NA62 experiment at the CERN SPS recorded in 2007 a large sample of K+ ? µ+?µ decays. A peak search in the missing mass spectrum of this decay is performed. In the absence of observed signal, the limits obtained on B(K+ ? µ+?h) and on the mixing matrix element |Uµ 4| are reported. The upgraded NA62 experiment started data taking in 2015. About 5×1011K+ decays have been recorded so far to measure the branching ratio of the K+ ? ?+?? decay. Preliminary results from the K+ ? ?+?? analysis based on about 5% of the 2016 statistics are reported.

Analysis of the Lepton Mixing Matrix from Neutrino Oscillation Experiments

1988

An analysis of experimental results in the framework of simultaneous oscillations of three neutrino flavours is used, in a combined fit, to constrain the elements of the 3×3 unitary lepton mixing matrix and to obtain limits on the three lepton mixing angles αeμ αeτ and αμτ. No evidence for mixing is found.

Present Knowledge of the Lepton Mixing Matrix from Neutrino Oscillation Experiments

1986

An analysis of experimental results in the framework of simultaneous oscillations of three neutrino flavours is used, in a combined fit, to constrain the elements of the 3 × 3 unitary lepton mixing matrix and to obtain limits on the three lepton mixing angles αeμ, αe τ and αμτ.

Proton-Neutron QRPA

2007

We discussed proton—neutron two-quasiparticle excitations and their electromagnetic and beta decays in Chap. 15. In Chap. 17 we introduced the pn-QTDA, the simplest configuration mixing scheme of these excitations. The vacuum of the pnQTDA is the BCS vacuum, and the solutions of the pn-QTDA satisfy a variational principle.1

10.7 Weak quark mixing and the CKM matrix

2008

Neutron distributions from pionic atoms

1992

Abstract The radii of neutron distributions in nuclei are extracted from experimental shifts and widths of pionic atoms. A best fit to pionic-atom data is carried out by varying simultaneously the neutron radii and the parameter of a pion-nucleus optical potential. We have used three different potentials: one of them theoretical plus a small phenomenological part, another one semiphenomenological, with the linear terms in the density obtained from experimental πN amplitudes and the quadratic terms fitted to the pionic-atom data, and a third one purely phenomenological, obtained from a direct fit to pionic-atom data. The radii obtained with all of them are remarkably close and also close to …

Neutrino-nuclear responses for astro-neutrinos, single beta decays and double beta decays

2019

Abstract Neutrino–nuclear responses associated with astro-neutrinos, single beta decays and double beta decays are crucial in studies of neutrino properties of interest for astro-particle physics. The present report reviews briefly recent studies of the neutrino–nuclear responses from both experimental and theoretical points of view in order to obtain a consistent understanding of the many facets of the neutrino–nuclear responses. Subjects discussed in this review include (i) experimental studies of neutrino–nuclear responses by means of single beta decays, charge-exchange nuclear reactions, muon- photon- and neutrino–nuclear reactions, and nucleon-transfer reactions, (ii) implications of a…

Shape dynamics in neutron-rich Kr isotopes: Coulomb excitation of 92Kr, 94Kr and 96Kr

2013

We report on the study of excited states in 92,94,96Kr populated via projectile Coulomb excitation at safe energies. The radioactive ion beams at energies of 2.85 MeV/u were delivered by the REX-ISOLDE facility at CERN and impinged on self-supporting 194,196Pt targets. The emitted γ -rays were detected by the Miniball detector-array. A detailed description of the experimental techniques used for extracting diagonal and transitional matrix elements and of the theoretical framework is given. The present experiment reveals the moderate evolution of the collective structure in the considered neutron-rich Kr isotopic chain, which is supported by the interacting boson model combined with the self…