2,982 research outputs found
Seesaw Mass Matrix Model of Quarks and Leptons with Flavor-Triplet Higgs Scalars
In a seesaw mass matrix model M_f = m_L M_F^{-1} m_R^\dagger with a universal
structure of m_L \propto m_R, as the origin of m_L (m_R) for quarks and eptons,
flavor-triplet Higgs scalars whose vacuum expectation values v_i are
proportional to the square roots of the charged lepton masses m_{ei}, i.e. v_i
\propto \sqrt{m_{ei}}, are assumed. Then, it is investigated whether such a
model can explain the observed neutrino masses and mixings (and also quark
masses and mixings) or not.Comment: version accepted by EPJ
A Unified Description of Quark and Lepton Mass Matrices in a Universal Seesaw Model
In the democratic universal seesaw model, the mass matrices are given by
\bar{f}_L m_L F_R + \bar{F}_L m_R f_R + \bar{F}_L M_F F_R (f: quarks and
leptons; F: hypothetical heavy fermions), m_L and m_R are universal for up- and
down-fermions, and M_F has a structure ({\bf 1}+ b_f X) (b_f is a
flavour-dependent parameter, and X is a democratic matrix). The model can
successfully explain the quark masses and CKM mixing parameters in terms of the
charged lepton masses by adjusting only one parameter, b_f. However, so far,
the model has not been able to give the observed bimaximal mixing for the
neutrino sector. In the present paper, we consider that M_F in the quark
sectors are still "fully" democratic, while M_F in the lepton sectors are
partially democratic. Then, the revised model can reasonably give a nearly
bimaximal mixing without spoiling the previous success in the quark sectors.Comment: 7 pages, no figur
Universal Seesaw Mass Matrix Model with an S_3 Symmetry
Stimulated by the phenomenological success of the universal seesaw mass
matrix model, where the mass terms for quarks and leptons f_i (i=1,2,3) and
hypothetical super-heavy fermions F_i are given by \bar{f}_L m_L F_R +\bar{F}_L
m_R f_R + \bar{F}_L M_F F_R + h.c. and the form of M_F is democratic on the
bases on which m_L and m_R are diagonal, the following model is discussed: The
mass terms M_F are invariant under the permutation symmetry S_3, and the mass
terms m_L and m_R are generated by breaking the S_3 symmetry spontaneously. The
model leads to an interesting relation for the charged lepton masses.Comment: 8 pages + 1 table, latex, no figures, references adde
Evolution of the Yukawa coupling constants and seesaw operators in the universal seesaw model
The general features of the evolution of the Yukawa coupling constants and
seesaw operators in the universal seesaw model with det M_F=0 are investigated.
Especially, it is checked whether the model causes bursts of Yukawa coupling
constants, because in the model not only the magnitude of the Yukawa coupling
constant (Y_L^u)_{33} in the up-quark sector but also that of (Y_L^d)_{33} in
the down-quark sector is of the order of one, i.e., (Y_L^u)_{33} \sim
(Y_L^d)_{33} \sim 1. The requirement that the model should be calculable
perturbatively puts some constraints on the values of the intermediate mass
scales and tan\beta (in the SUSY model).Comment: 21 pages, RevTex, 10 figure
Phenomenological approach to the critical dynamics of the QCD phase transition revisited
The phenomenological dynamics of the QCD critical phenomena is revisited.
Recently, Son and Stephanov claimed that the dynamical universality class of
the QCD phase transition belongs to model H. In their discussion, they employed
a time-dependent Ginzburg-Landau equation for the net baryon number density,
which is a conserved quantity. We derive the Langevin equation for the net
baryon number density, i.e., the Cahn-Hilliard equation. Furthermore, they
discussed the mode coupling induced through the {\it irreversible} current.
Here, we show the {\it reversible} coupling can play a dominant role for
describing the QCD critical dynamics and that the dynamical universality class
does not necessarily belong to model H.Comment: 13 pages, the Curie principle is discussed in S.2, to appear in
J.Phys.
Tribimaximal Neutrino Mixing and a Relation Between Neutrino- and Charged Lepton-Mass Spectra
Brannen has recently pointed out that the observed charged lepton masses
satisfy the relation m_e +m_\mu +m_\tau = {2/3}
(\sqrt{m_e}+\sqrt{m_\mu}+\sqrt{m_\tau})^2, while the observed neutrino masses
satisfy the relation m_{\nu 1} +m_{\nu 2} +m_{\nu 3} = {2/3} (-\sqrt{m_{\nu
1}}+\sqrt{m_{\nu 2}}+\sqrt{m_{\nu 3}})^2. It is discussed what neutrino Yukawa
interaction form is favorable if we take the fact pointed out by Brannen
seriously.Comment: 13 pages, presentation modifie
S_3 Symmetry and Neutrino Masses and Mixings
Based on a universal seesaw mass matrix model with three scalars \phi_i, and
by assuming an S_3 flavor symmetry for the Yukawa interactions, the lepton
masses and mixings are investigated systematically. In order to understand the
observed neutrino mixing, the charged leptons (e, \mu, \tau) are regarded as
the 3 elements (e_1, e_2, e_3) of S_3, while the neutrino mass-eigenstates are
regarded as the irreducible representation (\nu_\eta, \nu_\sigma, \nu_\pi) of
S_3, where (\nu_\pi, \nu_\eta) and \nu_\sigma are a doublet and a singlet,
respectively, which are composed of the 3 elements (\nu_1, \nu_2, \nu_3) of
S_3.Comment: 16 pages, no figure, version to appear in EPJ-
Role of Toll-like Receptor 2 in macrophage recognition and response to Borrelia burgdorferi
Lyme disease is the most common vector-borne disease in the US and will experience an uptick as the insect host, the ixodid tick, gains habitat with climate change. The causative agent of Lyme disease, Borrelia burgdorferi, is recognized by Toll-like receptor 2 (TLR2), which initiates the innate immune response. Here, I used ELISA and SEAP detection assays to determine that knocking out TLR2 in THP-1 macrophages reduces the amount of NFkB activation, as well as IL-10 and IL-1ÎČ secretion. Then, I used fluorescence microscopy and Incucyte assays to quantify the amount of phagocytosis performed by wild-type and knock-out THP-1 cells. I found that despite the changes in signaling, knock-out of TLR2 does not affect the extent of phagocytosis. These results support previous studies in mice that found that TLR2 knock-out impairs cytokine response but not phagocytic responses. Finally, I used a SEAP detection assay to measure the change in NFkB activation in HEK293T cells transfected with TLR2 mutants and stimulated with Borrelia. I found that 2 mutations, T411I and R753Q impair the NFkB activation response. Further study of these mutations may help to develop vaccines against Lyme disease by increasing understanding of the heterogeneity in immune responses to Borrelia
Volume, Coulomb, and volume-symmetry coefficients of nucleus incompressibility in the relativistic mean field theory with the excluded volume effects
The relation among the volume coefficient (=incompressibility of the
nuclear matter), the Coulomb coefficient , and the volume-symmetry
coefficient of the nucleus incompressibility are studied in the
framework of the relativistic mean field theory with the excluded volume
effects of the nucleons, under the assumption of the scaling model. It is found
that MeV is necessary to account for the empirical values of ,
, and , simultaneously, as is in the case of the point-like
nucleons. The result is independent on the detail descriptions of the potential
of the -meson self-interaction and is almost independent on the
excluded volume of the nucleons.Comment: PACS numbers, 21.65.+f, 21.30.+
Compressional properties of nuclear matter in the relativistic mean field theory with the excluded volume effects
Compressional properties of nuclear matter are studied by using the mean
field theory with the excluded volume effects of the nucleons. It is found that
the excluded volume effects make it possible to fit the empirical data of the
Coulomb coefficient of nucleus incompressibility, even if the volume
coefficient is small(MeV). However, the symmetry properties favor
MeV as in the cases of the mean field theory of point-like
nucleons.Comment: PACS numbers, 21.65.+f, 21.30.+
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