15,502 research outputs found
Neutrino Mixing via the Neutrino Portal
Relation between the lepton and quark mixings: , where is the BM or TBM mixing matrices, implies
the quark-lepton (Grand) unification and existence of hidden sector with
certain flavor symmetries. The latter couples to the visible sector via the
neutrino portal and is responsible for , as well as for smallness of
neutrino mass. GUT ensures appearance of in the lepton mixing.
General features of this scenario (inverse or double seesaw, screening of the
Dirac structures, basis fixing symmetry) are described and two realizations are
presented. The high energy realization is based on GUT with the hidden
sector at the Planck scale. The low energy realization includes the 100 TeV
scale symmetry and the hidden sector at the keV - MeV scale.Comment: LaTeX, 12 pages, 7 figure
Decoupling of heavy quarks in HQET
Decoupling of c-quark loops in b-quark HQET is considered. The decoupling
coefficients for the HQET heavy-quark field and the heavy-light quark current
are calculated with the three-loop accuracy. The last result can be used to
improve the accuracy of extracting f_B from HQET lattice simulations (without
c-quark loops). The decoupling coefficient for the flavour-nonsinglet QCD
current with n antisymmetrized gamma-matrices is also obtained at three loops;
the result for the tensor current (n=2) is new.Comment: JHEP3 documentclass; the results in a computer-readable form can be
found at http://www-ttp.physik.uni-karlsruhe.de/Progdata/ttp06/ttp06-25/ V2:
a few typos corrected, a few minor text improvements, a few references added;
V3: several typos in formulas fixe
Algebraic representation of correlation functions in integrable spin chains
Taking the XXZ chain as the main example, we give a review of an algebraic
representation of correlation functions in integrable spin chains obtained
recently. We rewrite the previous formulas in a form which works equally well
for the physically interesting homogeneous chains. We discuss also the case of
quantum group invariant operators and generalization to the XYZ chain.Comment: 31 pages, no figur
A recursion formula for the correlation functions of an inhomogeneous XXX model
A new recursion formula is presented for the correlation functions of the
integrable spin 1/2 XXX chain with inhomogeneity. It relates the correlators
involving n consecutive lattice sites to those with n-1 and n-2 sites. In a
series of papers by V. Korepin and two of the present authors, it was
discovered that the correlators have a certain specific structure as functions
of the inhomogeneity parameters. Our formula allows for a direct proof of this
structure, as well as an exact description of the rational functions which has
been left undetermined in the previous works.Comment: 37 pages, 1 figure, Proof of Lemma 4.8 modifie
Spin interfaces in the Ashkin-Teller model and SLE
We investigate the scaling properties of the spin interfaces in the
Ashkin-Teller model. These interfaces are a very simple instance of lattice
curves coexisting with a fluctuating degree of freedom, which renders the
analytical determination of their exponents very difficult. One of our main
findings is the construction of boundary conditions which ensure that the
interface still satisfies the Markov property in this case. Then, using a novel
technique based on the transfer matrix, we compute numerically the left-passage
probability, and our results confirm that the spin interface is described by an
SLE in the scaling limit. Moreover, at a particular point of the critical line,
we describe a mapping of Ashkin-Teller model onto an integrable 19-vertex
model, which, in turn, relates to an integrable dilute Brauer model.Comment: 12 pages, 6 figure
Two-Loop Static QCD Potential for General Colour State
In this letter, we extend the known results for the QCD potential between a
static quark and its antiquark by computing the two-loop corrections to the
colour-octet state.Comment: 7 page
Form factors of descendant operators: Free field construction and reflection relations
The free field representation for form factors in the sinh-Gordon model and
the sine-Gordon model in the breather sector is modified to describe the form
factors of descendant operators, which are obtained from the exponential ones,
\e^{\i\alpha\phi}, by means of the action of the Heisenberg algebra
associated to the field . As a check of the validity of the
construction we count the numbers of operators defined by the form factors at
each level in each chiral sector. Another check is related to the so called
reflection relations, which identify in the breather sector the descendants of
the exponential fields \e^{\i\alpha\phi} and \e^{\i(2\alpha_0-\alpha)\phi}
for generic values of . We prove the operators defined by the obtained
families of form factors to satisfy such reflection relations. A generalization
of the construction for form factors to the kink sector is also proposed.Comment: 29 pages; v2: minor corrections, some references added; v3: minor
corrections; v4,v5: misprints corrected; v6: minor mistake correcte
Bimaximal Neutrino Mixing with Discrete Flavour Symmetries
In view of the fact that the data on neutrino mixing are still compatible
with a situation where Bimaximal mixing is valid in first approximation and it
is then corrected by terms of order of the Cabibbo angle, we present examples
where these properties are naturally realized. The models are supersymmetric in
4-dimensions and based on the discrete non-Abelian flavour symmetry S4.Comment: 8 pages, 1 figure; contribution prepared for DISCRETE'10 - Symposium
on Prospects in the Physics of Discrete Symmetrie
Raising and lowering operators, factorization and differential/difference operators of hypergeometric type
Starting from Rodrigues formula we present a general construction of raising
and lowering operators for orthogonal polynomials of continuous and discrete
variable on uniform lattice. In order to have these operators mutually adjoint
we introduce orthonormal functions with respect to the scalar product of unit
weight. Using the Infeld-Hull factorization method, we generate from the
raising and lowering operators the second order self-adjoint
differential/difference operator of hypergeometric type.Comment: LaTeX, 24 pages, iopart style (late submission
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