Search results for "Mixing"
showing 10 items of 795 documents
Shape coexistence in neutron-deficient Hg isotopes studied via lifetime measurements inHg184,186and two-state mixing calculations
2014
The neutron-deficient mercury isotopes, $^{184,186}$Hg, were studied with the Recoil Distance Doppler Shift (RDDS) method using the Gammasphere array and the Koln Plunger device. The Differential Decay Curve Method (DDCM) was employed to determine the lifetimes of the yrast states in $^{184,186}$Hg. An improvement on previously measured values of yrast states up to $8^{+}$ is presented as well as first values for the $9_{3}$ state in $^{184}$Hg and $10^{+}$ state in $^{186}$Hg. $B(E2)$ values are calculated and compared to a two-state mixing model which utilizes the variable moment of inertia (VMI) model, allowing for extraction of spin-dependent mixing strengths and amplitudes.
CP violation and limits on New Physics including recent B-s measurements
2007
We analyse present constraints on the SM parameter space and derive, in a model independent way, various bounds on New Physics contributions to $B_d^0$--$\bar B_d^0$ and $B_s^0$--$\bar B_s^0$ mixings. Our analyses include information on a large set of asymmetries, leading to the measurement of the CKM phases $\gamma$ and $\bar\beta$, as well as recent data from D0 and CDF related to the $B_s^0$--$\bar B_s^0$ system such as the measurement of $\Delta M_{B_s}$, $A_{SL}$ and $\Delta\Gamma_{s}^{CP}$. We examine in detail several observables such as the asymmetries $A_{sl}^d$, $A_{SL}$, the width differences $\Delta\Gamma_{d}$ and $\Delta\Gamma_{s}^{CP}$ and discuss the r\^ole they play in estab…
Sweeping the Space of Admissible Quark Mass Matrices
2002
We propose a new and efficient method of reconstructing quark mass matrices from their eigenvalues and a complete set of mixing observables. By a combination of the principle of NNI (nearest neighbour interaction) bases which are known to cover the general case, and of the polar decomposition theorem that allows to convert arbitrary nonsingular matrices to triangular form, we achieve a parameterization where the remaining freedom is reduced to one complex parameter. While this parameter runs through the domain bounded by a circle with radius R determined by the up-quark masses around the origin in the complex plane one sweeps the space of all mass matrices compatible with the given set of d…
Fine structure in -decay and shape coexistence in
1999
Excited states in populated in the -decay of have been identified through -particle-conversion electron coincidences. The level scheme has been interpreted using a configuration mixing calculation, providing estimates of the mixing matrix elements, mixing amplitudes and the energies of unperturbed and unobserved levels.
a 0 (980)− f 0 (980) mixing in χ c1 → π 0 f 0 (980)→ π 0 π + π − and χ c1 → π 0 a 0 (980)→ π 0 π 0 η
2017
Abstract We study the isospin breaking in the reactions χ c 1 → π 0 π + π − and χ c 1 → π 0 π 0 η and its relation to the a 0 ( 980 ) − f 0 ( 980 ) mixing, which was measured by the BESIII Collaboration. We show that the same theoretical model previously developed to study the χ c 1 → η π + π − reaction (also measured by BESIII), and further explored in the predictions to the η c → η π + π − , can be successfully employed in the present study. We assume that the χ c 1 behaves as an S U ( 3 ) singlet to find the weight in which trios of pseudoscalars are created, followed by the final state interaction of pairs of mesons to describe how the a 0 ( 980 ) and f 0 ( 980 ) are dynamically generat…
Tri/Bi-maximal lepton mixing and leptogenesis
2009
In models with flavour symmetries added to the gauge group of the Standard Model the CP-violating asymmetry necessary for leptogenesis may be related with low-energy parameters. A particular case of interest is when the flavour symmetry produces exact Tri-Bimaximal lepton mixing leading to a vanishing CP-violating asymmetry. In this paper we present a model-independent discussion that confirms this always occurs for unflavoured leptogenesis in type I see-saw scenarios, noting however that Tri-Bimaximal mixing does not imply a vanishing asymmetry in general scenarios where there is interplay between type I and other see-saws. We also consider a specific model where the exact Tri-Bimaximal mi…
Predicting neutrino oscillations with “bi-large” lepton mixing matrices
2019
We propose two schemes for the lepton mixing matrix $U = U_l^\dagger U_\nu$, where $U = U_l$ refers to the charged sector, and $U_\nu$ denotes the neutrino diagonalization matrix. We assume $U_\nu$ to be CP conserving and its three angles to be connected with the Cabibbo angle in a simple manner. CP violation arises solely from the $U_l$, assumed to have the CKM form, $U_l\simeq V_{\rm CKM}$, suggested by unification. Oscillation parameters depend on a single parameter, leading to narrow ranges for the "solar" and "accelerator" angles $\theta_{12}$ and $\theta_{23}$, as well as for the CP phase, predicted as $\delta_{\rm CP}\sim 1.3\pi$.
Bilarge neutrino mixing and the Cabibbo angle
2012
Recent measurements of the neutrino mixing angles cast doubt on the validity of the so-far popular tri-bimaximal mixing ansatz. We propose a parametrization for the neutrino mixing matrix where the reactor angle seeds the large solar and atmospheric mixing angles, equal to each other in first approximation. We suggest such bi-large mixing pattern as a model building standard, realized when the leading order value of the reactor angle equals the Cabibbo angle.
Generation patterns, modified $\gamma-Z$ mixing, and hidden sector with dark matter candidates as framed standard model results
2018
A descriptive summary is given of the results to-date from the framed standard model (FSM) which: Assigns geometric meaning to the Higgs field and to fermion generations, hence offering an explanation for the observed mass and mixing patterns of quarks and leptons, reproducing near-quantitatively 17 of SM parameters with only 7. Predicts a new vector boson [Formula: see text] which mixes with [Formula: see text] and [Formula: see text], leading to deviations from the SM mixing scheme. For [Formula: see text] TeV, these deviations are within present experimental errors but should soon be detectable at LHC when experimental accuracy is further improved. Suggests the existence of a hidden sec…
Accidental stability of dark matter
2013
We propose that dark matter is stable as a consequence of an accidental Z(2) that results from a flavour symmetry group which is the double-cover group of the symmetry group of one of the regular geometric solids. Although model-dependent, the phenomenology resembles that of a generic >inert Higgs> dark matter scheme.