275 research outputs found
Radiative return method as a tool in hadronic physics
A short review of both theoretical and experimental aspects of the radiative
return method is presented. It is emphasised that the method gives not only
possibility of the independent from the scan method measurement of the hadronic
cross section, but also can provide information concerning details of the
hadronic interactions. New developments in the PHOKHARA event generator are
also reviewed. The 3 pion and kaon pair production is implemented within the
version 5.0 of the program, together with contributions of the radiative phi
decays to the 2 pion final states.
Missing NLO radiative corrections to the e+e- -> mu+ mu- gamma process will
be implemented in the forthcoming version of the generator
Electron-positron annihilation into phi f_{0}(980) and clues for a new 1^{--} resonance
We study the e^{+}e^{-} to phi pi pi reaction for pions in an isoscalar
s-wave which is dominated by loop mechanisms. For kaon loops we start from the
conventional RCHPT, but use the unitarized amplitude for KbarK-pipi scattering
and the full kaon form factor instead of the lowest order terms. We study also
effects of vector mesons using RCHPT supplemented with the conventional
anomalous term for VVP interactions and taking into account the effects of
heavy vector mesons in the K*K transition form factor. We find a peak in the
dipion invariant mass around the f_{0}(980) as in the experiment. Selecting the
phi f_{0}(980) contribution as a function of the e^{+}e^{-} energy we also
reproduce the experimental data except for a narrow peak, yielding support to
the existence of a 1^{--} resonance above the phi f_{0}(980) threshold,
coupling strongly to this state.Comment: 18 pages, 4 figure
Effects of physics beyond the standard model on the neutrino charge radius: an effective Lagrangian approach
In this work, we look for possible new physics effects on the electromagnetic
charge and anapole form factors, and , for a massless
Dirac neutrino, when these quantities are calculated in the context of an
effective electroweak Yang-Mills theory, which induces the most general
--invariant Lorentz tensor structure of nonrenormalizable type for the
vertex. It is found that in this context, besides the standard model
contribution, the additional contribution to and
( and , respectively) are gauge independent
and finite functions of after adopting a renormalization scheme. These
form factors, and , get contribution at
the one loop level only from the proper neutrino electromagnetic vertex.
Besides, the relation
(,
) is still fulfilled and
hence the relation (, )is gotten, just as in the SM. Using the experimental
constraint on the anomalous vertex, a value for the additional
contribution to the charge radius of |^{O_W}| \lsim 10^{-34}
cm^2 is obtained, which is one order of magnitude lower than the SM value.Comment: 9 pages, 3 figure
Efficacy of a zinc lactate mouthwash and tongue scraping in the reduction of oral halitosis: A single-blind, controlled, crossover clinical trial—a pilot study
Halitosis is defined as an unpleasant odor that comes out of the mouth. The aim of this study was to investigate the effect of zinc lactate mouthwash and tongue scraping on oral halitosis. The study was conducted on 60 volunteers that were divided into two groups and followed two types of 14-day oral hygiene protocols on a cross-over basis after a 7-day wash-out period. One protocol was based on tooth brushing only, while the other was based on additional mouth rinsing with a zinc lactate product and tongue scraping. Morning mouth breath was assessed organoleptic and by volatile sulfur compound concentrations. The highest mean organoleptic and volatile sulfur compound measurement values were found in the tooth brushing without mouth washing and tongue scraping oral hygiene protocol (p < 0.05). The zinc lactate mouthwash combined with tongue scraping appears to be an important hygienic procedure to reduce breath odor. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Positive and Negative Expectations of Hopelessness as Longitudinal Predictors of Depression, Suicidal Ideation, and Suicidal Behavior in High‐Risk Adolescents
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136513/1/sltb12273.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136513/2/sltb12273_am.pd
Improved Term of the Electron Anomalous Magnetic Moment
We report a new value of electron , or , from 891 Feynman diagrams
of order . The FORTRAN codes of 373 diagrams containing closed
electron loops have been verified by at least two independent formulations. For
the remaining 518 diagrams, which have no closed lepton loop, verification by a
second formulation is not yet attempted because of the enormous amount of
additional work required. However, these integrals have structures that allow
extensive cross-checking as well as detailed comparison with lower-order
diagrams through the renormalization procedure. No algebraic error has been
uncovered for them. The numerical evaluation of the entire term by
the integration routine VEGAS gives , where the
uncertainty is obtained by careful examination of error estimates by VEGAS.
This leads to ,
where the uncertainties come from the term, the estimated
uncertainty of term, and the inverse fine structure constant,
, measured by atom interferometry combined
with a frequency comb technique, respectively. The inverse fine structure
constant derived from the theory and the Seattle
measurement of is .Comment: 64 pages and 10 figures. Eq.(16) is corrected. Comments are added
after Eq.(40
Evaluating potential of leaf reflectance spectra to monitor plant genetic variation
Remote sensing of vegetation by spectroscopy is increasingly used to characterize trait distributions in plant communities. How leaves interact with electromagnetic radiation is determined by their structure and contents of pigments, water, and abundant dry matter constituents like lignins, phenolics, and proteins. High-resolution ("hyperspectral") spectroscopy can characterize trait variation at finer scales, and may help to reveal underlying genetic variation-information important for assessing the potential of populations to adapt to global change. Here, we use a set of 360 inbred genotypes of the wild coyote tobacco Nicotiana attenuata: wild accessions, recombinant inbred lines (RILs), and transgenic lines (TLs) with targeted changes to gene expression, to dissect genetic versus non-genetic influences on variation in leaf spectra across three experiments. We calculated leaf reflectance from hand-held field spectroradiometer measurements covering visible to short-wave infrared wavelengths of electromagnetic radiation (400-2500 nm) using a standard radiation source and backgrounds, resulting in a small and quantifiable measurement uncertainty. Plants were grown in more controlled (glasshouse) or more natural (field) environments, and leaves were measured both on- and off-plant with the measurement set-up thus also in more to less controlled environmental conditions. Entire spectra varied across genotypes and environments. We found that the greatest variance in leaf reflectance was explained by between-experiment and non-genetic between-sample differences, with subtler and more specific variation distinguishing groups of genotypes. The visible spectral region was most variable, distinguishing experimental settings as well as groups of genotypes within experiments, whereas parts of the short-wave infrared may vary more specifically with genotype. Overall, more genetically variable plant populations also showed more varied leaf spectra. We highlight key considerations for the application of field spectroscopy to assess genetic variation in plant populations
Event by Event Analysis and Entropy of Multiparticle Systems
The coincidence method of measuring the entropy of a system, proposed some
time ago by Ma, is generalized to include systems out of equilibrium. It is
suggested that the method can be adapted to analyze multiparticle states
produced in high-energy collisions.Comment: 13 pages, 2 figure
Genetic constraints on temporal variation of airborne reflectance spectra and their uncertainties over a temperate forest
Remote sensing enhances large-scale biodiversity monitoring by overcoming temporal and spatial limitations of ground-based measurements and allows assessment of multiple plant traits simultaneously. The total set of traits and their variation over time is specific for each individual and can reveal information about the genetic composition of forest communities. Measuring trait variation among individuals of one species continuously across space and time is a key component in monitoring genetic diversity but difficult to achieve with ground-based methods. Remote sensing approaches using imaging spectroscopy can provide high spectral, spatial, and temporal coverage to advance the monitoring of genetic diversity, if sufficient relation between spectral and genetic information can be established.
We assessed reflectance spectra from individual Fagus sylvatica L. (European beech) trees acquired across eleven years from 69 flights of the Airborne Prism Experiment (APEX) above the same temperate forest in Switzerland. We derived reflectance spectra of 68 canopy trees and correlated differences in these spectra with genetic differences derived from microsatellite markers among the 68 individuals. We calculated these correlations for different points in time, wavelength regions and relative differences between wavelength regions. High correlations indicate high spectral-genetic similarities. We then tested the influence of environmental variables obtained at temporal scales from days to years on spectral-genetic similarities. We performed an uncertainty propagation of radiance measurements to provide a quality indicator for these correlations.
We observed that genetically similar individuals had more similar reflectance spectra, but this varied between wavelength regions and across environmental variables. The short-wave infrared regions of the spectrum, influenced by water absorption, seemed to provide information on the population genetic structure at high temperatures, whereas the visible part of the spectrum, and the near-infrared region affected by scattering properties of tree canopies, showed more consistent patterns with genetic structure across longer time scales. Correlations of genetic similarity with reflectance spectra similarity were easier to detect when investigating relative differences between spectral bands (maximum correlation: 0.40) than reflectance data (maximum correlation: 0.33). Incorporating uncertainties of spectral measurements yielded improvements of spectral-genetic similarities of 36% and 20% for analyses based on single spectral bands, and relative differences between spectral bands, respectively.
This study highlights the potential of dense multi-temporal airborne imaging spectroscopy data to detect the genetic structure of forest communities. We suggest that the observed temporal trajectories of reflectance spectra indicate physiological and possibly genetic constraints on plant responses to environmental change
Electromagnetic Form Factors of a Massive Neutrino
Electromagnetic form factors of a massive neutrino are studied in a minimally
extended standard model in an arbitrary gauge and taking into account
the dependence on the masses of all interacting particles. The contribution
from all Feynman diagrams to the charge, magnetic, and anapole form factors, in
which the dependence on the masses of all particles as well as on gauge
parameters is accounted for exactly, are obtained for the first time in
explicit form. The asymptotic behavior of the magnetic form factor for large
negative squares of the momentum of an external photon is analyzed and
expression for the anapole moment of a massive neutrino is derived. The results
are generalized to the case of mixing between various generations of the
neutrino. Explicit expressions are obtained for the charge, magnetic, and
electric dipole and anapole transition form factors as well as for the
transition electric dipole moment.Comment: 16 pares with 5 figures in pdf forma
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