Physics Letters B 741 (2015) 210–216
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Scaling ansatz with texture zeros in linear seesaw
Mainak Chakraborty
a
, H. Zeen Devi
b
, Ambar Ghosal
a,∗
a
Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India
b
University of Technology and Management, Shillong 793003, India
a r t i c l e i n f o a b s t r a c t
Article history:
Received
17 October 2014
Received
in revised form 26 November 2014
Accepted
17 December 2014
Available
online 23 December 2014
Editor:
J. Hisano
We investigate scaling ansatz with texture zeros within the framework of linear seesaw mechanism. In
this variant of seesaw mechanism a simplified expression of effective neutrino mass matrix m
ν
containing
two Dirac type matrices (m
D
and m
DS
) and one Majorana type matrix (m
RS
) is obtained by virtue of
neglecting the global U (1)
L
symmetry breaking term in the mass term of the Lagrangian. Along with
the charged lepton mass matrix, the matrix m
RS
, too, is chosen in a diagonal basis whereas a scaling
relation is incorporated in m
D
and m
DS
with different scale factors. Our goal in this work is to achieve
a completely phenomenologically acceptable m
ν
generated by combinations of m
D
and m
DS
containing
least number of independent parameters or maximum number of zeros. At the end of the numerical
analysis it is found that number of zeros in any of the constituent Dirac type matrices (m
D
and m
DS
)
of m
ν
cannot be greater than six in order to meet the phenomenological requirements. The hierarchy
obtained here is normal and also the values of the two parameters sum mass (
m
i
) and |m
ν
ee
| are
below the present experimental lower limit.
© 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
1. Introduction
In the quest towards understanding of a viable flavour structure
of low-energy neutrino mass matrix adhering neutrino oscillation
data, a general approach is to advocate flavour symmetries in con-
junction
with the standard SU(2)
L
× U (1)
Y
model. Those additional
flavour symmetries are associated with some gauge group, discrete
or continuous, and thereby dictating a well-defined theory to ex-
plain
the extant data. This is a task to realize a comprehensive
theory in the ultimate goal to comply with all experimental re-
sults.
On the contrary, realization of a viable neutrino mass matrix
through the proposition of some ansatz at low energy is also a
supportive way towards the quest of a more elucidative model.
In
the present work we investigate the latter idea considering
two ansatzes, (i) zeros in the Yukawa texture, (ii) a scaling prop-
erty
between the nonzero Yukawa matrix elements, referred to as
scaling ansatz [1–11] within the framework of a variant of see-
saw
mechanism known as “linear seesaw” mechanism [12–16]. We
do not touch the origin of those two well-studied ansatzes here,
however, we bring the two ansatzes together here and investi-
gate
systematically the minimal number of parameters necessary
*
Corresponding author.
E-mail
addresses: mainak.chakraborty@saha.ac.in (M. Chakraborty),
zdevi@utm.ac.in (H. Zeen Devi), ambar.ghosal@saha.ac.in (A. Ghosal).
to explain the neutrino experimental data within the above men-
tioned
framework. We briefly mention few words regarding scaling
ansatz. Imposition of scaling ansatz correlates the nonzero ele-
ments
of Yukawa matrix by a scale factor and it can be achieved
through different ways. One of the distinctive properties of scaling
ansatz is that the texture remains invariant under renormaliza-
tion
group evolution. Furthermore, this ansatz leads to m
3
= 0 and
θ
13
= 0. Thus we are compelled to break the ansatz to generate
nonzero θ
13
.
Texture
zeros [17–30] are investigated in the literature within
different framework to generate light neutrino masses. Here, we
start with maximum number of zeros in Yukawa matrix and inves-
tigate
by reducing the number of zeros till we get a minimum of
necessary
parameters to explain neutrino oscillation data [31–33].
Our
plan of the paper is as follows. Section 2 deals with lin-
ear
seesaw mechanism framework. The scaling ansatz considered
is given in Section 3. Section 4 contains analysis with texture ze-
ros.
Parametrization and diagonalization of the emerged neutrino
mass matrices is shown in Section 5. Discussion on numerical re-
sult
is given in Section 6. Section 7 contains the summary and
conclusion of the present work.
2. Linear seesaw
In linear seesaw, the effective neutrino mass matrix (m
ν
) gener-
ated
varies linearly with Dirac neutrino mass matrix (m
D
) instead
http://dx.doi.org/10.1016/j.physletb.2014.12.038
0370-2693/
© 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.