Search results for "Absolut"

Modelling tribimaximal neutrino mixing

2009

We model tribimaximal lepton mixing from first principles in a way that avoids the problem of the vacuum alignment characteristic of such models. This is achieved by using a softly broken A(4) symmetry realized with an isotriplet fermion, also triplet under A(4). No scalar A(4) triplet is introduced. This represents one possible realization of general schemes characterized by the minimal set of either three or five physical parameters. In the three parameter versions the neutrinoless double beta mass parameter m(ee) vanishes, while in the five parameter schemes the absolute scale of neutrino mass, although not predicted, is related to the two Majorana phases. The model realization we discus…

Measurement ofCPviolation parameters inB0→DK*0decays

2014

An analysis of B0→DK*0 decays is presented, where D represents an admixture of D0 and D¯0 mesons reconstructed in four separate final states: K−π+, π−K+, K+K− and π+π−. The data sample corresponds to 3.0  fb−1 of proton-proton collision, collected by the LHCb experiment. Measurements of several observables are performed, including CP asymmetries. The most precise determination is presented of rB(DK*0), the magnitude of the ratio of the amplitudes of the decay B0→DK+π− with a b→u or a b→c transition, in a Kπ mass region of ±50  MeV/c2 around the K∗(892) mass and for an absolute value of the cosine of the K*0 helicity angle larger than 0.4.

On the Gerasimov-Drell-Hearn sum rule for the deuteron

1997

The Gerasimov-Drell-Hearn sum rule is evaluated for the deuteron by explicit integration up to a photon energy of 550 MeV including contributions from the photodisintegration channel and from coherent and incoherent single pion production as well. The photodisintegration channel converges fast enough in this energy range and gives a large negative contribution, essentially from the $^1S_0$ resonant state near threshold. Its absolute value is about the same size than the sum of proton and neutron GDH values. It is only partially cancelled by the single pion production contribution. But the incoherent channel has not reached convergence at 550 MeV.

Efficiency calibration of a Ge(Li) detector by absolute counting of fallout nuclides by means of the 4πβ-γ coincidence method

1975

Abstract The 4 π β - γ coincidence method proves to be very suitable for absolute counting of fallout nuclides. Using such nuclides, absolute calibration of a Ge(Li) detector was carried out for different geometry positions.

Phase-stable free-space optical lattices for trapped ions

2015

We demonstrate control of the absolute phase of an optical lattice with respect to a single trapped ion. The lattice is generated by off-resonant free-space laser beams, we actively stabilize its phase by measuring its ac-Stark shift on a trapped ion. The ion is localized within the standing wave to better than 2\% of its period. The locked lattice allows us to apply displacement operations via resonant optical forces with a controlled direction in phase space. Moreover, we observe the lattice-induced phase evolution of spin superposition states in order to analyze the relevant decoherence mechanisms. Finally, we employ lattice-induced phase shifts for inferring the variation of the ion pos…

PROJECT 8: A FREQUENCY-BASED APPROACH TO MEASURE THE ABSOLUTE NEUTRINO MASS SCALE

2021

Fascinating puzzle called double beta decay

2019

The question of whether neutrinos are Majorana or Dirac particles and what are their average masses remains one of the most fundamental problems in physics today. Observation of neutrinoless double beta decay (0νββ) would verify the Majorana nature of the neutrino and constrain the absolute scale of the neutrino mass spectrum. The inverse half-life for 0νββ-decay is given by the product of a phase space factor (PSF), a nuclear matrix element (NME), which both rely on theoretical description, and a function f containing the physics beyond the standard model. Recent calculations of PSF and NME will be reviewed together with comparison to other available results. These calculations serve the p…

One and two dimensional tunnel junction arrays in weak Coulomb blockade regime-absolute accuracy in thermometry

1999

We have investigated one and two dimensional (1D and 2D) arrays of tunnel junctions in partial Coulomb blockade regime. The absolute accuracy of the Coulomb blockade thermometer is influenced by the external impedance of the array, which is not the same in the different topologies of 1D and 2D arrays. We demonstrate, both by experiment and by theoretical calculations in simple geometries, that the 1D structures are better in this respect. Yet in both 1D and 2D, the influence of the environment can be made arbitrarily small by making the array sufficiently large.

Atomic transition probabilities of F I spectral lines from3s−3pand3p−3dtransition arrays

1999

We have measured the relative transition probabilities of about $100 3s\ensuremath{-}3p$ and $3p\ensuremath{-}3d$ lines of neutral fluorine in the visible and near-infrared spectrum with a wall-stabilized high-current arc, which is operated under conditions very close to partial local thermodynamic equilibrium. The set of measured lines includes about 40 intersystem transitions. Our data have been placed on an absolute scale by normalizing several strong transitions to the results of the OPACITY Project calculations, which are expected to be quite accurate for such transitions. We estimate that the uncertainties of our absolute transition probability values are in the \ifmmode\pm\else\textp…

The energy calibration of LEP in the 1993 scan

1995

This report summarizes the procedure for providing the absolute energy calibration of the LEP beams during the energy scan in 1993. The average beam energy around the LEP ring was measured in 25 calibrations with the resonant depolarization technique. The time variation of this average beam energy is well described by a model of the accelerator based on monitored quantities. The absolute calibration of the centre of mass energies of the off-peak points is determined with a precision of 2 parts in 10(5) resulting in a systematic error on the Z-mass of about 1.4 MeV and on the Z-width of about 1.5 MeV.