45 research outputs found
Universal Texture of Quark and Lepton Mass Matrices
Against the conventional picture that the mass matrix forms in the quark
sectors will take somewhat different structures from those in the lepton
sectors, a possibility that all the mass matrices of quarks and leptons have
the same form as in the neutrinos is investigated. For the lepton sectors, the
model leads to a nearly bimaximal mixing with the prediction
|U_{e3}|^2=m_e/2m_\mu=0.0024 and \tan^2\theta_{sol} \simeq m_{\nu 1}/m_{\nu 2},
and so on. For the quark sectors, it can lead to reasonable values of the CKM
mixing matrix and masses: |V_{us}|\simeq \sqrt{m_d/m_s}, |V_{ub}| \simeq
|V_{cb}|\sqrt{m_u/m_c}, |V_{td}| \simeq |V_{cb}|\cdot |V_{us}|, and so on.Comment: 9 pages, Latex, talk given at The 4th workshop on "Neutrino
Oscillations and their Origin" (NOON2003) (Kanazawa, Japan, 10--14 Feb.
2002). To appear in the Proceeding
How to Evade a No-Go Theorem in Flavor Symmetries
A no-go theorem in flavor symmetries is reviewed. The theorem asserts that we
cannot bring any flavor symmetry into mass matrix model in which number of
Higgs scalars is, at most, one for each sector (e.g. H_u and H_d for up- and
down-quark sectors, respectively). Such the strong constraint comes from the
SU(2)_L symmetry. Possible three options to evade the theorem are discussed.Comment: 10 pages, no figure, talk given at International Workshop on Grand
Unified Theories: Current Status and Future Prospects, Kusatsu, Japan,
December 17 - 19, 200
Neutrino Mixing based on Mass Matrices with a Symmetry
Under the assumption that the symmetry is broken only
through phases, we give a systematical investigation of possible lepton mass
matrix forms without referring to the explicit parameter values. The two types
of the symmetry are investigated: one is that the left-
and right-handed fields obey the symmetry, and another one is that
only obeys the symmetry. In latter case, in spite of no symmetry in the Majorana mass matrix for , the neutrino seesaw
mass matrix still obey the symmetry. Possible
phenomenologies are discussed.Comment: 12 pages, title and conclusions modifie
What Happens If an Unbroken Flavor Symmetry Exists?
Without assuming any specific flavor symmetry and/or any specific mass matrix
forms, it is demonstrated that if a flavor symmetry (a discrete symmetry, a
U(1) symmetry, and so on) exists, we cannot obtain the CKM quark mixing matrix
and the MNS lepton mixing matrix except for those between two families
for the case with the completely undegenerated fermion masses, so that we can
never give the observed CKM and MNS mixings. Only in the limit of (), we can obtain three family mixing with an interesting
constraint ().Comment: 10 pages, no figure, title and presentation change
Universal Texture of Quark and Lepton Mass Matrices and a Discrete Symmetry Z_3
Recent neutrino data have been favourable to a nearly bimaximal mixing, which
suggests a simple form of the neutrino mass matrix. Stimulated by this matrix
form, a possibility that all the mass matrices of quarks and leptons have the
same form as in the neutrinos is investigated. The mass matrix form is
constrained by a discrete symmetry Z_3 and a permutation symmetry S_2. The
model, of course, leads to a nearly bimaximal mixing for the lepton sectors,
while, for the quark sectors, it can lead to reasonable values of the CKM
mixing matrix and masses.Comment: 24 pages, RevTEX, no figure, some references and comments were adde
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
Occupational risk factors for Parkinson's disease: a case-control study in Japan
<p>Abstract</p> <p>Background</p> <p>The evidence for associations between occupational factors and the risk of Parkinson's disease (PD) is inconsistent. We assessed the risk of PD associated with various occupational factors in Japan.</p> <p>Methods</p> <p>We examined 249 cases within 6 years of onset of PD. Control subjects were 369 inpatients and outpatients without neurodegenerative disease. Information on occupational factors was obtained from a self-administered questionnaire. Relative risks of PD were estimated using odds ratios (ORs) and 95% confidence intervals (CIs) based on logistic regression. Adjustments were made for gender, age, region of residence, educational level, and pack-years of smoking.</p> <p>Results</p> <p>Working in a professional or technical occupation tended to be inversely related to the risk of PD: adjusted OR was 0.59 (95% CI: 0.32-1.06, <it>P </it>= 0.08). According to a stratified analysis by gender, the decreased risk of PD for persons in professional or technical occupations was statistically significant only for men. Adjusted ORs for a professional or technical occupation among men and women were 0.22 (95% CI: 0.06-0.67) and 0.99 (0.47-2.07), respectively, and significant interaction was observed (<it>P </it>= 0.048 for homogeneity of OR). In contrast, risk estimates for protective service occupations and transport or communications were increased, although the results were not statistically significant: adjusted ORs were 2.73 (95% CI: 0.56-14.86) and 1.74 (95% CI: 0.65-4.74), respectively. No statistical significance was seen in data concerning exposure to occupational agents and the risk of PD, although roughly a 2-fold increase in OR was observed for workers exposed to stone or sand.</p> <p>Conclusion</p> <p>The results of our study suggest that occupational factors do not play a substantial etiologic role in this population. However, among men, professional or technical occupations may decrease the risk of PD.</p
Alcohol drinking and risk of Parkinson's disease: a case-control study in Japan
<p>Abstract</p> <p>Background</p> <p>Although some epidemiologic studies found inverse associations between alcohol drinking and Parkinson's disease (PD), the majority of studies found no such significant associations. Additionally, there is only limited research into the possible interactions of alcohol intake with aldehyde dehydrogenase (ALDH) 2 activity with respect to PD risk. We examined the relationship between alcohol intake and PD among Japanese subjects using data from a case-control study.</p> <p>Methods</p> <p>From 214 cases within 6 years of PD onset and 327 controls without neurodegenerative disease, we collected information on "peak", as opposed to average, alcohol drinking frequency and peak drinking amounts during a subject's lifetime. Alcohol flushing status was evaluated via questions, as a means of detecting inactive ALHD2. The multivariate model included adjustments for sex, age, region of residence, smoking, years of education, body mass index, alcohol flushing status, presence of selected medication histories, and several dietary factors.</p> <p>Results</p> <p>Alcohol intake during peak drinking periods, regardless of frequency or amount, was not associated with PD. However, when we assessed daily ethanol intake separately for each type of alcohol, only Japanese sake (rice wine) was significantly associated with PD (adjusted odds ratio of ≥66.0 g ethanol per day: 3.39, 95% confidence interval: 1.10-11.0, <it>P </it>for trend = 0.001). There was no significant interaction of alcohol intake with flushing status in relation to PD risk.</p> <p>Conclusions</p> <p>We did not find significant associations between alcohol intake and PD, except for the daily amount of Japanese sake. Effect modifications by alcohol flushing status were not observed.</p