scholarly journals Determination of the Kobayashi-Maskawa-Cabibbo matrix elementVusunder various flavor-symmetry-breaking models in hyperon semileptonic decays

1996 ◽  
Vol 54 (11) ◽  
pp. 6855-6860 ◽  
Author(s):  
R. Flores-Mendieta ◽  
A. García ◽  
G. Sánchez-Colón
Keyword(s):  
Symmetry Breaking ◽  
Semileptonic Decays ◽  
Flavor Symmetry

EXPERIMENTAL DETERMINATION OF THE QUARK MIXING ANGLES

1991 ◽  
Vol 06 (18) ◽  
pp. 3293-3320 ◽  
Author(s):  
G. LÓPEZ CASTRO
Keyword(s):  
Experimental Data ◽  
Symmetry Breaking ◽  
Current Status ◽  
Flavor Symmetry ◽  
Matrix Elements ◽  
Mixing Angles ◽  
Decay Properties ◽  
Quark Mixing ◽  
Exclusive Decay

We review the current status of the determination of the quark mixing angles |Vqq′|, where q=u, c; q′=d, s, b. We consider essentially exclusive decay processes, taking into account the main sources of uncertainties, the available calculations of flavor symmetry breaking for hadronic matrix elements and the possibilities of improvement offered by new experimental results. In some cases we provide full expressions for |Vqq′| in terms of measurable decay properties, which can be useful for new experimental data. Finally, we discuss briefly the effects on the unitarity tests of the Cabibbo-Kobayashi-Maskawa matrix when we consider recent corrections to the determination of |Vud|.

Symmetry breaking in convergent-beam diffraction

1989 ◽  
Vol 47 ◽  
pp. 480-481
Author(s):  
D.J. Eaglesham
Keyword(s):  
Symmetry Breaking ◽  
Point Group ◽  
X Ray Diffraction ◽  
Multiple Diffraction ◽  
Space Groups ◽  
Atomic Displacements ◽  
Small Probe ◽  
Phase Sensitive ◽  
Convergent Beam

Convergent Beam Electron Diffraction is now almost routinely used in the determination of the point- and space-groups of crystalline samples. In addition to its small-probe capability, CBED is also postulated to be more sensitive than X-ray diffraction in determining crystal symmetries. Multiple diffraction is phase-sensitive, so that the distinction between centro- and non-centro-symmetric space groups should be trivial in CBED: in addition, the stronger scattering of electrons may give a general increase in sensitivity to small atomic displacements. However, the sensitivity of CBED symmetry to the crystal point group has rarely been quantified, and CBED is also subject to symmetry-breaking due to local strains and inhomogeneities. The purpose of this paper is to classify the various types of symmetry-breaking, present calculations of the sensitivity, and illustrate symmetry-breaking by surface strains.CBED symmetry determinations usually proceed by determining the diffraction group along various zone axes, and hence finding the point group. The diffraction group can be found using either the intensity distribution in the discs

scholarly journals Flavor symmetry breaking in the 1/Ncexpansion

1996 ◽  
Vol 53 (1) ◽  
pp. 273-282 ◽  
Author(s):  
Jin Dai ◽  
Roger Dashen ◽  
Elizabeth Jenkins ◽  
Aneesh V. Manohar
Keyword(s):  
Symmetry Breaking ◽  
Flavor Symmetry

scholarly journals The determination of point groups from imprecise molecular geometries

2021 ◽  
Author(s):  
Peter J. Knowles
Keyword(s):  
Symmetry Breaking ◽  
Point Group ◽  
Simple Function ◽  
Coordinate Frame ◽  
New Approach ◽  
Measure Of Symmetry ◽  
Point Groups

AbstractWe present a new approach for the assignment of a point group to a molecule when the structure conforms only approximately to the symmetry. It proceeds by choosing a coordinate frame that minimises a measure of symmetry breaking that is computed efficiently as a simple function of the molecular coordinates and point group specification.

Flavons and LFV decays and productions of pseudoscalar mesons

2019 ◽  
Vol 34 (35) ◽  
pp. 1950288
Author(s):  
Tian-Qi Li ◽  
Chong-Xing Yue
Keyword(s):  
Standard Model ◽  
Symmetry Breaking ◽  
Flavor Symmetry ◽  
Lepton Flavor ◽  
Flavor Changing ◽  
Pseudoscalar Mesons ◽  
The Standard Model

Flavons are the dynamic agent of flavor symmetry breaking and have flavor changing couplings to the Standard Model (SM) fermions. We consider their contributions to the lepton flavor violating (LFV) decays [Formula: see text] and [Formula: see text] with [Formula: see text], [Formula: see text] or [Formula: see text] and [Formula: see text] in the simplest flavon model without Higgs-flavon mixing. We find that flavons can produce significant contributions to some of these LFV decay processes.

scholarly journals Flavor symmetry breaking in the Δ sea

2019 ◽  
Vol 100 (3) ◽  
Author(s):  
J. J. Ethier ◽  
W. Melnitchouk ◽  
Fernanda Steffens ◽  
A. W. Thomas
Keyword(s):  
Symmetry Breaking ◽  
Flavor Symmetry

scholarly journals BARYONS AS THREE-FLAVOR SOLITONS

1996 ◽  
Vol 11 (14) ◽  
pp. 2419-2544 ◽  
Author(s):  
HERBERT WEIGEL
Keyword(s):  
Symmetry Breaking ◽  
Vector Meson ◽  
Degrees Of Freedom ◽  
Magnetic Moments ◽  
Axial Vector ◽  
Vector Current ◽  
Bound State ◽  
Axial Vector Current ◽  
Flavor Symmetry ◽  
Matrix Elements

The description of baryons as soliton solutions of effective meson theories for three-flavor (up, down and strange) degrees of freedom is reviewed and the phenomenological implications are illuminated. In the collective approach the soliton configuration is equipped with baryon quantum numbers by canonical quantization of the coordinates describing the flavor orientation. The baryon spectrum resulting from exact diagonalization of the collective Hamiltonian is discussed. The prediction of static properties, such as the baryon magnetic moments and the Cabibbo matrix elements for semileptonic hyperon decays, are explored with regard to the influence of flavor symmetry breaking. In particular, the role of strange degrees of freedom in the nucleon is investigated for both the vector and axial vector current matrix elements. The latter are discussed extensively within the context of the proton spin puzzle. The influence of flavor symmetry breaking on the shape of the soliton is examined, and observed to cause significant deviations from flavor-covariant predictions on the baryon magnetic moments. Short range effects are incorporated by a chirally invariant inclusion of vector meson fields. These extensions are necessary for properly describing the singlet axial vector current and the neutron–proton mass difference. The effects of the vector meson excitations on baryon properties are also considered. The bound state description of hyperons and its generalization to baryons containing a heavy quark are illustrated. In the case of the Skyrme model a comparison is made between the collective quantization scheme and the bound state approach. Finally, the Nambu–Jona-Lasinio model is employed to demonstrate that hyperons can be described as solitons in a microscopic theory of the quark flavor dynamics. This is explained for both the collective and the bound state approaches to strangeness.

scholarly journals SPIN STRUCTURE OF THE PROTON

1995 ◽  
Vol 10 (23) ◽  
pp. 1659-1666
Author(s):  
CHUNG-YI WU
Keyword(s):  
Symmetry Breaking ◽  
Spin Structure ◽  
Flavor Symmetry ◽  
Leading Order ◽  
Intrinsic Polarization

By assuming that there is no significant intrinsic polarization of the gluon, we have computed the polarized quark contributions to the proton’s spin under SU(3) flavor symmetry breaking for the polarized sea and have performed a global leading-order QCD fit to obtain the spin-dependent quark distributions, which could be used as input for analyzing lepton-hadron and hadron-hadron collisions.

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