Browsing by Author "Okamura, Naotoshi"

Now showing 1 - 20 of 21
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    Classical Implications of the Minimal Length Uncertainty Relation
    Benczik, S. Z.; Chang, Lay Nam; Minic, Djordje; Okamura, Naotoshi; Rayyan, S.; Takeuchi, Tatsu (2002-09-12)
    We study the phenomenological implications of the classical limit of the "stringy" commutation relations [x_i,p_j]=i hbar[(1+beta p^2) delta_{ij} + beta' p_i p_j]. In particular, we investigate the "deformation" of Kepler's third law and apply our result to the rotation curves of gas and stars in spiral galaxies.
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    Constraints on New Physics from Long Baseline Neutrino Oscillation Experiments
    Honda, M.; Kao, Y.; Okamura, Naotoshi; Pronin, A.; Takeuchi, Tatsu (2007)
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    Constraints on New Physics from Matter Effects on Neutrino Oscillation
    Honda, M.; Kao, Y.; Okamura, Naotoshi; Pronin, A.; Takeuchi, Tatsu (2006)
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    Effect of the minimal length uncertainty relation on the density of states and the cosmological constant problem
    Chang, Lay Nam; Minic, Djordje; Okamura, Naotoshi; Takeuchi, Tatsu (American Physical Society, 2002-06-15)
    We investigate the effect of the minimal length uncertainty relation, motivated by perturbative string theory, on the density of states in momentum space. The relation is implemented through the modified commutation relation [(x) over cap (i),(p) over cap (j)]=i (h) over bar[(1+beta(p) over cap (2))delta(ij)+beta(')(p) over cap (i)(p) over cap (j)]. We point out that this relation, which is an example of a UV/IR relation, implies the finiteness of the cosmological constant. While our result does not solve the cosmological constant problem, it does shed new light on the relation between this outstanding problem and UV/IR correspondence. We also point out that the blackbody radiation spectrum will be modified at higher frequencies, but the effect is too small to be observed in the cosmic microwave background spectrum.
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    Effect of the minimal length uncertainty relation on the density of states and the cosmological constant problem
    Chang, Lay Nam; Minic, Djordje; Okamura, Naotoshi; Takeuchi, Tatsu (American Physical Society, 2002-06-15)
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    The Effect of Topcolor Assisted Technicolor, and other models, on Neutrino Oscillation
    Honda, M.; Kao, Y.; Okamura, Naotoshi; Pronin, A.; Takeuchi, Tatsu (2007)
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    Exact solution of the harmonic oscillator in arbitrary dimensions with minimal length uncertainty relations
    Chang, Lay Nam; Minic, Djordje; Okamura, Naotoshi; Takeuchi, Tatsu (American Physical Society, 2002-06-15)
    We determine the energy eigenvalues and eigenfunctions of the harmonic oscillator where the coordinates and momenta are assumed to obey the modified commutation relations [(x) over cap (i),(p) over cap (j)]=i (h) over bar[(1+beta(p) over cap (2))delta(ij)+beta(')(p) over cap (i)(p) over cap (j)]. These commutation relations are motivated by the fact that they lead to the minimal length uncertainty relations which appear in perturbative string theory. Our solutions illustrate how certain features of string theory may manifest themselves in simple quantum mechanical systems through the modification of the canonical commutation relations. We discuss whether such effects are observable in precision measurements on electrons trapped in strong magnetic fields.
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    Exact solution of the harmonic oscillator in arbitrary dimensions with minimal length uncertainty relations
    Chang, Lay Nam; Minic, Djordje; Okamura, Naotoshi; Takeuchi, Tatsu (American Physical Society, 2002-06-15)
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    Leptonic CP violation search and the ambiguity of delta m(31)(2)
    Koike, M.; Okamura, Naotoshi; Saito, M.; Takeuchi, Tatsu (American Physical Society, 2006-03)
    We consider a search for the CP-violating angle delta(CP) in long baseline neutrino oscillation experiments. We show that the subleading delta(CP)-dependent terms in the nu(mu)->nu(e) oscillation probability can be easily obscured by the ambiguity of the leading term which depends on parallel to delta m(31)(2)parallel to. It is thus necessary to determine the value of delta m(31)(2) with a sufficient accuracy. The nu(mu) survival events, which can be accumulated simultaneously with the nu(e) appearance events, can serve for this purpose owing to its large statistics. Therefore, the combined analysis of nu(e) appearance and nu(mu) survival events is crucial to provide a restrictive constraint on delta(CP). Taking a test experimental setup, we demonstrate in the delta(CP)-delta m(31)(2) plane that the analysis of nu(e) appearance events leads to less restrictive constraints on the value of delta(CP) due to the ambiguity of delta m(31)(2) and that the combined analysis efficiently improves the constraints.
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    Leptonic CP violation search and the ambiguity of delta m(31)(2)
    Koike, M.; Okamura, Naotoshi; Saito, M.; Takeuchi, Tatsu (American Physical Society, 2006-03-01)
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    NuTeV anomaly, lepton universality, and nonuniversal neutrino-gauge couplings
    Loinaz, William; Okamura, Naotoshi; Rayyan, S.; Takeuchi, Tatsu; Wijewardhana, L. C. R. (American Physical Society, 2004-12)
    In previous studies we found that models with flavor-universal suppression of the neutrino-gauge couplings are compatible with NuTeV and Z-pole data. In this paper we expand our analysis to obtain constraints on flavor-dependent coupling suppression by including lepton universality data from W, tau, pi and K decays in fits to model parameters. We find that the data are consistent with a variety of patterns of coupling suppression. In particular, in scenarios in which the suppression arises from the mixing of light neutrinos with heavy gauge singlet states (neutrissimos), we find patterns of flavor-dependent coupling suppression which are also consistent with constraints from mu-->egamma.
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    NuTeV anomaly, lepton universality, and nonuniversal neutrino-gauge couplings
    Loinaz, William; Okamura, Naotoshi; Rayyan, S.; Takeuchi, Tatsu; Wijewardhana, L. C. R. (American Physical Society, 2004-12-01)
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    NuTeV anomaly, neutrino mixing, and a heavy Higgs boson
    Loinaz, William; Okamura, Naotoshi; Takeuchi, Tatsu; Wijewardhana, L. C. R. (American Physical Society, 2003-04-01)
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    NuTeV anomaly, neutrino mixing, and a heavy Higgs boson
    Loinaz, William; Okamura, Naotoshi; Takeuchi, Tatsu; Wijewardhana, L. C. R. (American Physical Society, 2003-04)
    Recent results from the NuTeV experiment at Fermilab and the deviation of the Z invisible width, measured at CERN LEP and the SLAC Linear Collider, from its standard model (SM) prediction suggest the suppression of neutrino-Z couplings. Such suppressions occur naturally in models which mix the neutrinos with heavy gauge singlet states. We postulate a universal suppression of the Znunu couplings by a factor of (1-epsilon) and perform a fit to the Z-pole and NuTeV observables with epsilon and the oblique correction parameters S and T. Compared to a fit with S and T only, the inclusion of epsilon leads to a dramatic improvement in the quality of the fit. The values of S and T preferred by the fit can be obtained within the SM by a simple increase in the Higgs boson mass. However, if the W mass is also included in the fit, a non-zero U parameter becomes necessary which cannot be supplied within the SM. The preferred value of epsilon suggests that the seesaw mechanism may not be the reason why neutrinos are so light.
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    Quark-lepton unification and lepton flavor nonconservation from a TeV-scale seesaw neutrino mass texture
    Loinaz, William; Okamura, Naotoshi; Rayyan, S.; Takeuchi, Tatsu; Wijewardhana, L. C. R. (American Physical Society, 2003-10-01)
    In a recent paper we pointed out that the mixing of the light neutrinos with heavy gauge singlet states could reconcile the Z-pole data from e(+)e(-) colliders and the nu(mu) ((nu) over bar (mu)) scattering data from the NuTeV experiment at Fermilab. We further noted that the mixing angle required to fit the data is much larger than what would be expected from the conventional seesaw mechanism. In this paper, we show how such mixings can be arranged by a judicious choice of the neutrino mass texture. We also argue that by invoking the unification of the Dirac mass matrix for the up-type quarks and the neutrinos, the mass of the heavy states can naturally be expected to lie in the few TeV range. The model is strongly constrained by the lepton flavor changing process mu-->egamma which requires lepton universality to be violated in the charged channel.
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    Quark-lepton unification and lepton flavor nonconservation from a TeV-scale seesaw neutrino mass texture
    Loinaz, William; Okamura, Naotoshi; Rayyan, S.; Takeuchi, Tatsu; Wijewardhana, L. C. R. (American Physical Society, 2003-10-01)
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    Short distance versus long distance physics: The classical limit of the minimal length uncertainty relation
    Benczik, S. Z.; Chang, Lay Nam; Minic, Djordje; Okamura, Naotoshi; Rayyan, S.; Takeuchi, Tatsu (American Physical Society, 2002-07-15)
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    Short distance versus long distance physics: The classical limit of the minimal length uncertainty relation
    Benczik, S. Z.; Chang, Lay Nam; Minic, Djordje; Okamura, Naotoshi; Rayyan, S.; Takeuchi, Tatsu (American Physical Society, 2002-07-15)
    We continue our investigation of the phenomenological implications of the "deformed" commutation relations [(x) over cap (i),(p) over cap (j)]=i (h) over bar[(1+beta(p) over cap (2))delta(ij)+beta'(p) over cap (i)(p) over cap (j)]. These commutation relations are motivated by the fact that they lead to the minimal length uncertainty relation which appears in perturbative string theory. In this paper, we consider the effects of the deformation on the classical orbits of particles in a central force potential. Comparison with observation places severe constraints on the value of the minimum length.
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    A Simple parameterization of matter effects on neutrino oscillations
    Honda, M.; Kao, Y.; Okamura, Naotoshi; Takeuchi, Tatsu (2006)