34,735 research outputs found
Probing Extra Dimensions with Neutrino Oscillations
In the braneworld scenario, gravity and neutrino oscillation can both be used
to detect the presence of an extra dimension. We argue that neutrino
oscillation is particularly suitable if the size of the extra dimension is
small, in which case the signature for the extra dimension is the disappearance
of active neutrino fluxes into the bulk, caused by the destructive interference
from the Kaluza-Klein states. We discuss a class of models to illustrate this
general feature.Comment: 16 pages, no figures. A contribution in honor of Hiroshi Ezawa on his
70th birthday. To appear in `Garden of Quanta' (World Scientific
Decomposition of Time-Ordered Products and Path-Ordered Exponentials
We present a decomposition formula for , an integral of time-ordered
products of operators, in terms of sums of products of the more primitive
quantities , which are the integrals of time-ordered commutators of the
same operators. The resulting factorization enables a summation over to be
carried out to yield an explicit expression for the time-ordered exponential,
an expression which turns out to be an exponential function of . The
Campbell-Baker-Hausdorff formula and the nonabelian eikonal formula obtained
previously are both special cases of this result.Comment: 31 pages, Revtex with two postscript figure
Mass Independent Textures and Symmetry
A mass-independent texture is a set of linear relations of the fermion
mass-matrix elements which imposes no constraint on the fermionic masses nor
the Majorana phases. Magic and 2-3 symmetries are examples. We discuss the
general construction and the properties of these textures, as well as their
relation to the quark and neutrino mixing matrices. Such a texture may be
regarded as a symmetry, whose unitary generators of the symmetry group can be
explicitly constructed. In particular, the symmetries connected with the
tri-bimaximal neutrino mixing matrix are discussed, together with the physical
consequence of breaking one symmetry but preserving another.Comment: Version to be published in PRD. References modified, and a misprint
in eq (9) is correcte
Horizontal Symmetry from the Bottom Up
A general method to derive horizontal symmetry from a mixing matrix is
reviewed. The technique has been applied to deduce leptonic symmetry from the
tri-bimaximal neutrino mixing matrix and three of its variations. The question
of how the quark mixing can be accommodated within the leptonic symmetry group
is discussed, including in this connection an example based on the group .Comment: Luxor09 talk, 7 page
A 2-3 Symmetry in Neutrino Oscillations
Maximum mixing in atmospheric neutrino oscillation, as well as vanishing of
the MNS matrix element , are consequences of a 2-3 symmetry, under
which the neutrino mass matrix is invariant under the interchange of second and
third generation neutrinos. These predictions of the 2-3 symmetry are
consistent with the results of Super-Kamiokande, K2K, and CHOOZ experiments. If
the symmetry is exact at a high-energy scale set by right-handed neutrinos, a
deviation from these predictions generated by renormalization-group corrections
will occur at experimental energies. With an MSSM dynamics, the result can be
made to agree with a global fit of the neutrino data, if normal hierarchy is
assumed on the neutrino mass spectrum and if the mass of the electron-neutrino
is at least about 0.025 eV. The presence of this mass lower bound is a novel
and interesting feature of the symmetry that can be falsified by future
experiments. Of the three viable solar neutrino solutions, only LMA gives a
sizable MNS matrix element that can hopefully be detected in future
reactor experiments. Inverted neutrino mass hierarchy is not permitted by this
symmetry.Comment: to appear in Phys. Lett.
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