2,382 research outputs found
Up-Down Unification just above the supersymmetric threshold
Large corrections to the quark mass matrices at the supersymmetric threshold
allow the theory to have identical Yukawa matrices in the superpotential. We
demonstrate that Up-Down unification can take place in a moderate quark-squark
alignment scenario with an average squark mass of the order 1 TeV and with
Comment: 12 pages, latex, two figure
How natural is a small \bar\theta in left-right SUSY models ?
In the world without an axion the smallness of may be achieved
due to a spontaneously broken discrete left-right symmetry. We analyze the
radiatively induced \bar\theta in the context of generic left-right symmetric
SUSY models without assuming flavor degeneracy in the squark sector. Left-right
symmetry allows to keep \bar\theta within its present bound only if the
inter-generational mass splitting in the squark sector at the scale of the
left-right symmetry breaking is smaller than 0.5%. We also consider the
naturalness of m_u=0 solution to the strong CP problem in the context of
horizontal flavor symmetries. A strong bound on the combination of the
horizontal charges in the Up quark sector is found in this case.Comment: 12 pages, latex, 1 figure, references adde
Minimal Ten-parameter Hermitian Texture Zeroes Mass Matrices and the CKM Matrix
Hermitian mass matrices for the up and down quarks with texture zeroes but
with the minimum number of parameters, ten, are investigated. We show how these
{\em minimum parameter} forms can be obtained from a general set of hermitian
matrices through weak basis transformations. For the most simple forms we show
that one can derive exact and compact parametrizations of the CKM mixing matrix
in terms of the elements of these mass matrices (and the quark masses).Comment: 14 pages.Talk given by M.B. at the MRST 98, ``Towards the Theory of
Everything", Montr\'eal, 13-15 May 199
Unified Flavor Symmetry from warped dimensions
We propose a scenario which accommodates all the masses and mixings of the SM
fermions in a model of warped extra-dimensions with all matter fields in the
bulk. In this scenario, the same flavor symmetric structure is imposed on all
the fermions of the Standard Model (SM), including neutrinos. Due to the
exponential sensitivity on bulk fermion masses, a small breaking of the
symmetry can be greatly enhanced and produce seemingly un-symmetric
hierarchical masses and small mixing angles among the charged fermion
zero-modes (SM quarks and charged leptons) and wash-out the obvious effects of
the symmetry. With the Higgs field leaking into the bulk, and Dirac neutrinos
sufficiently localized towards the UV boundary, the neutrino mass hierarchy and
flavor structure will still be largely dominated by the fundamental flavor
structure. The neutrino sector would then reflect the fundamental flavor
structure, whereas the quark sector would probe the effects of the flavor
symmetry breaking sector. As an example, we explore these features in the
context of a family permutation symmetry imposed in both quark and lepton
sectors.Comment: 5 pages, 1 figur
Canonical Constraints on Leptonic Cp Violation using UHCR neutrino fluxes
It is shown that one can in principle constrain the CP-violating parameter
delta from measurements of four independant |V_{ij}|^2, or three of them and a
ratio, in the leptonic sector. To quantify our approach, using unitarity, we
derive simple expressions in terms of four independant |V_{ij}|^2 for
cos(delta) and an expression for sin^2(delta) from J^2. Thus, depending on the
values of |V_{ij}| and their accuracy, we can set meaningful limits on |delta|.
To illustrate numerically, if |V_{u1}|^2 is close to 0.1 with a 10% precision,
and if |V_{e3}^2 is larger than 0.005 and for values of |V_{e2}|^2 and
|V_{u3}|^2 that stay within +-0.1 of the current experimental data leads to a
bound pi/2 < |delta| < pi. Alternatively, a certain combination of parameters
with values of |V_{e3}|^2 larger than 0.01 leads to a closed bound of 73 <
|delta| < 103. In general, we find that it is better to use |V_{u1}|^2 or
|V_{t1}|^2 as the fourth independant |V_{ij}|^2 and that over most of the
parameter space, delta is least sensitive to |V_{e3}|^2. With just three
independant measurements (solar, atmospheric and reactor) it is impossible to
set limits on the CP phase. In this respect, we study the use of ultra high
energy cosmic (UHCR) neutrino fluxes as the additional fourth information. We
find that within the SM, neutrino fluxes of all three flavours will be very
similar but that pushing current neutrino data to their extreme values still
allowed, ratios of cosmic neutrino fluxes can differ by up to 20%; such large
discrepancies could imply negligibly small CP-violation. We also study a non
radiative neutrino decay model and find that the neutrino fluxes can differ by
a factor of up to 3 within this model and that an accuracy of 10% on the
neutrino fluxes is sufficient to set interestin limits on delta.Comment: 8 pages, 2 figures, 5 table
- …