11,158 research outputs found
Leptons in Holographic Composite Higgs Models with Non-Abelian Discrete Symmetries
We study leptons in holographic composite Higgs models, namely in models
possibly admitting a weakly coupled description in terms of five-dimensional
(5D) theories. We introduce two scenarios leading to Majorana or Dirac
neutrinos, based on the non-abelian discrete group which is
responsible for nearly tri-bimaximal lepton mixing. The smallness of neutrino
masses is naturally explained and normal/inverted mass ordering can be
accommodated. We analyze two specific 5D gauge-Higgs unification models in
warped space as concrete examples of our framework. Both models pass the
current bounds on Lepton Flavour Violation (LFV) processes. We pay special
attention to the effect of so called boundary kinetic terms that are the
dominant source of LFV. The model with Majorana neutrinos is compatible with a
Kaluza-Klein vector mass scale TeV, which is roughly the
lowest scale allowed by electroweak considerations. The model with Dirac
neutrinos, although not considerably constrained by LFV processes and data on
lepton mixing, suffers from a too large deviation of the neutrino coupling to
the boson from its Standard Model value, pushing TeV.Comment: 37 pages, 4 figures; v2: Note added in light of recent T2K and MINOS
results, figures updated with new limit from MEG, references added, various
minor improvements, matches JHEP published versio
Stripe State in the Lowest Landau Level
The stripe state in the lowest Landau level is studied by the density matrix
renormalization group (DMRG) method. The ground state energy and pair
correlation functions are systematically calculated for various
pseudopotentials in the lowest Landau level. We show that the stripe state in
the lowest Landau level is realized only in a system whose width perpendicular
to the two-dimensional electron layer is smaller than the order of magnetic
length.Comment: 4 pages, 6 figures, to appear in J. Phys. Soc. Jpn. vol.73 No.1
(2004
Measurement agreement between a newly developed sensing insole and traditional laboratory-based method for footstrike pattern detection in runners
This study introduced a novel but simple method to continuously measure footstrike patterns in runners using inexpensive force sensors. Two force sensing resistors were firmly affixed at the heel and second toe of both insoles to collect the time signal of foot contact. A total of 109 healthy young adults (42 males and 67 females) were recruited in this study. They ran on an instrumented treadmill at 0˚, +10˚, and -10˚ inclinations and attempted rearfoot, midfoot, and forefoot landings using real time visual biofeedback. Intra-step strike index and onset time difference between two force sensors were measured and analyzed with univariate linear regression. We analyzed 25,655 footfalls and found that onset time difference between two sensors explained 80–84% of variation in the prediction model of strike index (R-squared = 0.799–0.836, p<0.001). However, the time windows to detect footstrike patterns on different surface inclinations were not consistent. These findings may allow laboratory-based gait retraining to be implemented in natural running environments to aid in both injury prevention and performance enhancement
Superrelativity as a unification of quantum theory and relativity(II)
A underlying dynamical structure for both relativity and quantum
theory-``superrelativity'' has been proposed in order to overcome the well
known incompatibility between these theories. The relationship between
curvature of spacetime (gravity) and curvature of the projective Hilbert space
of pure quantum states is established as well.Comment: 6 pages,LaTeX,In the Abstract ``proposed on order'' should be read as
``proposed in order'
Reevaluating electron-phonon coupling strengths: Indium as a test case for ab initio and many-body-theory methods
Using indium as a test case, we investigate the accuracy of the
electron-phonon coupling calculated with state-of-the-art ab initio and
many-body theory methods. The ab initio calculations -- where electrons are
treated in the local-density approximation, and phonons and the electron-phonon
interaction are treated within linear response -- predict an electron-phonon
spectral function alpha^2 F(omega) which translates into a relative tunneling
conductance that agrees with experiment to within one part in 1000. The
many-body theory calculations -- where alpha^2 F(omega) is extracted from
tunneling data by means of the McMillan-Rowell tunneling inversion method --
provide spectral functions that depend strongly on details of the inversion
process. For the the most important moment of alpha^2 F(omega), the
mass-renormalization parameter lambda, we report 0.9 +/- 0.1, in contrast to
the value 0.805 quoted for nearly three decades in the literature. The ab
initio calculations also provide the transport electron-phonon spectral
function alpha_{tr}^2 F(omega), from which we calculate the resistivity as a
function of temperature in good agreement with experiment.Comment: 16 pages, 5 figure
Two-soliton solution for the derivative nonlinear Schr\"odinger equation with nonvanishing boundary conditions
An explicit two-soliton solution for the derivative nonlinear Schr\"odinger
equation with nonvanishing boundary conditions is derived, demonstrating
details of interactions between two bright solitons, two dark solitons, as well
as one bright soliton and one dark soliton. Shifts of soliton positions due to
collisions are analytically obtained, which are irrespective of the bright or
dark characters of the participating solitons.Comment: 11 pages, 4 figures. Phys. Lett. A 2006 (in press
Higher-order non-symmetric counterterms in pure Yang-Mills theory
We analyze the restoration of the Slavnov-Taylor (ST) identities for pure
massless Yang-Mills theory in the Landau gauge within the BPHZL renormalization
scheme with IR regulator. We obtain the most general form of the action-like
part of the symmetric regularized action, obeying the relevant ST identities
and all other relevant symmetries of the model, to all orders in the loop
expansion. We also give a cohomological characterization of the fulfillment of
BPHZL IR power-counting criterion, guaranteeing the existence of the limit
where the IR regulator goes to zero. The technique analyzed in this paper is
needed in the study of the restoration of the ST identities for those models,
like the MSSM, where massless particles are present and no invariant
regularization scheme is known to preserve the full set of ST identities of the
theory.Comment: Final version published in the journa
Clustering of childhood leukaemia in Hong Kong: association with the childhood peak and common acute lymphoblastic leukaemia and with population mixing.
Incidence data of childhood leukaemia (CL) in Hong Kong (1984-90) have been analysed for evidence of variation between small areas. All cases (n=261) were classified by morphological cell type, with the majority (n=205) being acute lymphoblastic leukaemia (ALL), and haematological review has permitted immunophenotypic classification for 73% of these. The data have been examined for evidence of spatial clustering within small census areas (TPUs) and for association with population mixing, with attention focused on those subgroups (especially the childhood peak of ALL--taken here to be diagnoses in children from 24 months up to the seventh birthday--and common ALL) which, it has been hypothesized, may be caused by unusual patterns of exposure and response to common infections. For the whole of Hong Kong, there was evidence of spatial clustering of ALL at ages 0-4 years (P = 0.09) and in the childhood peak (P<0.05). When these analyses were restricted to TPUs where extreme population mixing may have occurred, overall incidence was elevated and significant evidence of clustering was found for ALL (P<0.007) at these ages and for the common ALL in the childhood peak (P = 0.032). Replication of the analyses for subsets of leukaemia that were not dominated by the childhood peak of ALL found no evidence of clustering. This is the first investigation of an association between population mixing and childhood leukaemia in Asia and the first to include clustering and to consider particular subsets. The results are supportive of the 'infectious' aetiology hypothesis for subsets of childhood leukaemia, specifically common ALL in the childhood peak
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