1,560 research outputs found
Orbifold Family Unification in SO(2N) Gauge Theory
We study the possibility of family unification on the basis of SO(2N) gauge
theory on the five-dimensional space-time, . Several SO(10),
or SU(5) multiplets come from a single
bulk multiplet of SO(2N) after the orbifold breaking. Other multiplets
including brane fields are necessary to compose three families of quarks and
leptons.Comment: 28 page
Relation between the neutrino and quark mixing angles and grand unification
We argue that there exists simple relation between the quark and lepton
mixings which supports the idea of grand unification and probes the underlying
robust bi-maximal fermion mixing structure of still unknown flavor physics. In
this framework the quark mixing matrix is a parameter matrix describing the
deviation of neutrino mixing from exactly bi-maximal, predicting
theta_{sol}+theta_C=pi/4, where theta_C is the Cabibbo angle,
theta_{atm}+theta_{23}^{CKM}=pi/4 and theta_{13}^{MNS} ~ theta_{13}^{CKM} ~
O(lambda^3), in a perfect agreement with experimental data. Both non-Abelian
and Abelian flavor symmetries are needed for such a prediction to be realistic.
An example flavor model capable to explain this flavor mixing pattern, and to
induce the measured quark and lepton masses, is outlined.Comment: references added, title changed in journa
Discussions on Stability of Diquarks
Since the birth of the quark model, the diquark which is composed of two
quarks has been considered as a substantial structure of color anti-triplet.
This is not only a mathematical simplification for dealing with baryons, but
also provides a physical picture where the diquark would behave as a whole
object. It is natural to ask whether such a structure is sufficiently stable
against external disturbance. The mass spectra of the ground states of the
scalar and axial-vector diquarks which are composed of two-light (L-L),
one-light-one-heavy (H-L) and two-heavy quarks (H-H) respectively have been
calculated in terms of the QCD sum rules. We suggest a criterion as the
quantitative standard for the stability of the diquark. It is the gap between
the masses of the diquark and where is the threshold of the
excited states and continuity, namely the larger the gap is, the more stable
the diquark would be. In this work, we calculate the masses of the type H-H to
complete the series of the spectra of the ground state diquarks. However, as
the criterion being taken, we find that all the gaps for the various diquaks
are within a small range, especially the gap for the diquark with two heavy
quarks which is believed to be a stable structure, is slightly smaller than
that for other two types of diquarks, therefore we conclude that because of the
large theoretical uncertainty, we cannot use the numerical results obtained
with the QCD sum rules to assess the stability of diquarks, but need to invoke
other theoretical framework.Comment: 14 pages, 4 figure
On the Early History of Current Algebra
The history of Current Algebra is reviewed up to the appearance of the
Adler-Weisberger sum rule. Particular emphasis is given to the role current
algebra played for the historical struggle in strong interaction physics of
elementary particles between the S-matrix approach based on dispersion
relations and field theory. The question whether there are fundamental
particles or all hadrons are bound or resonant states of one another played an
important role in this struggle and is thus also regarded.Comment: 17 page
Maximally Entangled Mixed States and Conditional Entropies
The maximally entangled mixed states of Munro, James, White, and Kwiat [Phys.
Rev. A {\bf 64} (2001) 030302] are shown to exhibit interesting features vis a
vis conditional entropic measures. The same happens with the Ishizaka and
Hiroshima states [Phys. Rev. A {\bf 62} 022310 (2000)], whose
entanglement-degree can not be increased by acting on them with logic gates.
Special types of entangled states that do not violate classical entropic
inequalities are seen to exist in the space of two qubits. Special meaning can
be assigned to the Munro {\it et al.} special participation ratio of 1.8
A Comprehensive Mechanism Reproducing the Mass and Mixing Parameters of Quarks and Leptons
It is shown that if, from the starting point of a universal rank-one mass
matrix long favoured by phenomenologists, one adds the assumption that it
rotates (changes its orientation in generation space) with changing scale, one
can reproduce, in terms of only 6 real parameters, all the 16 mass ratios and
mixing parameters of quarks and leptons. Of these 16 quantities so reproduced,
10 for which data exist for direct comparison (i.e. the CKM elements including
the CP-violating phase, the angles in
-oscillation, and the masses ) agree well with
experiment, mostly to within experimental errors; 4 others (), the experimental values for which can only be inferred, agree
reasonably well; while 2 others ( for leptons), not yet
measured experimentally, remain as predictions. In addition, one gets as
bonuses, estimates for (i) the right-handed neutrino mass and (ii)
the strong CP angle inherent in QCD. One notes in particular that the
output value for from the fit agrees very well with
recent experiments. By inputting the current experimental value with its error,
one obtains further from the fit 2 new testable constraints: (i) that
must depart from its "maximal" value: , (ii) that the CP-violating (Dirac) phase in the PMNS would be
smaller than in the CKM matrix: of order only if
not vanishing altogether.Comment: 37 pages, 1 figur
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