2,311 research outputs found
Complete One-Loop Renormalization of the Higgs-Electroweak Chiral Lagrangian
Employing background-field method and super-heat-kernel expansion, we compute
the complete one-loop renormalization of the electroweak chiral Lagrangian with
a light Higgs boson. Earlier results from purely scalar fluctuations are
confirmed as a special case. We also recover the one-loop renormalization of
the conventional Standard Model in the appropriate limit.Comment: 15 pages, no figures; v2: reference and comments added, typos fixed,
matches published versio
An example of resonance saturation at one loop
We argue that the large-Nc expansion of QCD can be used to treat a Lagrangian
of resonances in a perturbative way. As an illustration of this we compute the
L_10 coupling of the Chiral Lagrangian by integrating out resonance fields at
one loop. Given a Lagrangian and a renormalization scheme, this is how in
principle one can answer in a concrete and unambiguous manner questions such as
at what scale resonance saturation takes place.Comment: 9 pages, 5 figures. Enlarged discussion, results unchanged. To be
published in Phys. Rev.
Noncommutative Geometry and the standard model with neutrino mixing
We show that allowing the metric dimension of a space to be independent of
its KO-dimension and turning the finite noncommutative geometry F-- whose
product with classical 4-dimensional space-time gives the standard model
coupled with gravity--into a space of KO-dimension 6 by changing the grading on
the antiparticle sector into its opposite, allows to solve three problems of
the previous noncommutative geometry interpretation of the standard model of
particle physics:
The finite geometry F is no longer put in "by hand" but a conceptual
understanding of its structure and a classification of its metrics is given.
The fermion doubling problem in the fermionic part of the action is resolved.
The spectral action of our joint work with Chamseddine now automatically
generates the full standard model coupled with gravity with neutrino mixing and
see-saw mechanism for neutrino masses. The predictions of the Weinberg angle
and the Higgs scattering parameter at unification scale are the same as in our
joint work but we also find a mass relation (to be imposed at unification
scale).Comment: Typos removed, to appear in JHE
Error estimates for pi-pi scattering threshold parameters in Chiral Perturbation Theory to two loops
Using the analysis of ChPT to two loops, we perform an error analysis of the
threshold and low energy parameters, based on the uncertainties for the one
loop low energy parameters and the resonance saturation mechanism. Different
sets of one loop low energy constants have been considered.Thus, the predictive
power of the effective field theory is quantified on the basis of the present
experimental uncertainties.Comment: 12 pages, 2 tables, 3 figures. Numerics upgraded to v2 of ref.(8).
New reference added. Typos corrected. New figure for SU(3) parameters
include
Work-life conflicts and health among Swiss physicians--in comparison with other university graduates and with the general Swiss working population
QUESTION UNDER STUDY: The present study aimed to compare the prevalence of work-life conflicts and the health status of physicians, with a representative sample of university graduates as well as with a representative sample of the general Swiss working population. Furthermore, it aimed to analyse whether work-life conflicts correlate with the health of physicians, as it does in the general working population. METHODS: The present cross-sectional study analysed data from 2007 originating from the SwissMedCareer Study (a prospective cohort study of physicians who graduated in 2001; n = 543) and the Swiss Household Panel (a representative Swiss survey on living and working conditions; university graduates of the same age range: n = 172, general working population of the same age range: n = 670). Data were analysed with Chi2 tests, correlations and logistic regressions. RESULTS: Physicians reported strong time-based as well as strain-based work-life conflicts more frequently than university graduates and the general working population. Significantly more physicians reported "moderate" to "very poor" health than the other two samples. Surprisingly, on the other side of the scale ("very good" health), physicians outnumbered the other samples too. Strong associations between work-life conflict and self-rated health as well as various health complaints were found for physicians. CONCLUSION: The high prevalence of work-life conflicts may explain the comparably high prevalence of poor self-rated health in the physicians' sample
Kaon mixing and the charm mass
We study contributions to the Delta S=2 weak Chiral Lagrangian producing
K0-K0bar mixing which are not enhanced by the charm mass. For the real part,
these contributions turn out to be related to the box diagram with up quarks
but, unlike in perturbation theory, they do not vanish in the limit m_u->0.
They increase the leading contribution to the K_L-K_S mass difference by ~10%.
This means that short distances amount to (90+-15)% of this mass difference.
For the imaginary part, we find a correction to the lambda_c^2 m_c^2 term of
-5% from the integration of charm, which is a small contribution to epsilon_K.
The calculation is done in the large-Nc limit and we show explicitly how to
match short and long distances.Comment: 20 pages, 5 figures. Typos fixe
Heavy mass expansion, light-by-light scattering and the anomalous magnetic moment of the muon
Contributions from light-by-light scattering to (g_\mu-2)/2, the anomalous
magnetic moment of the muon, are mediated by the exchange of charged fermions
or scalar bosons. Assuming large masses M for the virtual particles and
employing the technique of large mass expansion, analytical results are
obtained for virtual fermions and scalars in the form of a series in (m_\mu
/M)^2. This series is well convergent even for the case M=m_\mu. For virtual
fermions, the expansion confirms published analytical formulae. For virtual
scalars, the result can be used to evaluate the contribution from charged
pions. In this case our result confirms already available numerical
evaluations, however, it is significantly more precise.Comment: revtex4, eps figure
Contribution of higher meson resonances to the electromagnetic -meson mass difference
Modifications of the DGMLY relation for calculation of electromagnetic
-meson mass difference based on the Chiral Symmetry Restoration phenomenon
at high energies as well as the Operator Product Expansion of quark densities
for vector () and axial-vector () meson fields difference are
proposed. In the calculations higher meson resonances in vector and
axial-vector channels are taken into account. It is shown that the inclusion of
the first and radial excitations improves the results for
electromagnetic -meson mass difference as compared with the previous ones.
Estimations on the electromagnetic and -meson decay constants and
the constant of effective chiral Lagrangian are obtained from the
generalized Weinberg sum rules.Comment: Latex2e, 10 pages, submitted to Yad. Phy
Direct calculation of the probability of pionium ionization in the target
We performed the first direct calculation of the probability of pionium
(pi+pi- atom) ionization in the target. The dependence of the probability of
pionium ionization in the target as a function of the pionium lifetime is
established. These calculations are of interest of the DIRAC experiment at
CERN, which aims to measure the pionium lifetime with high precision.Comment: 11 pages, 4 figures; submitted to "Physics of Atomic Nuclei"
("Yadernaya Fizika"
Hadronic light-by-light corrections to the muon g-2: the pion-pole contribution
The correction to the muon anomalous magnetic moment from the pion-pole
contribution to the hadronic light-by-light scattering is considered using a
description of the pi0 - gamma* - gamma* transition form factor based on the
large-Nc and short-distance properties of QCD. The resulting two-loop integrals
are treated by first performing the angular integration analytically, using the
method of Gegenbauer polynomials, followed by a numerical evaluation of the
remaining two-dimensional integration over the moduli of the Euclidean loop
momenta. The value obtained, a_{mu}(LbyL;pi0) = +5.8 (1.0) x 10^{-10},
disagrees with other recent calculations. In the case of the vector meson
dominance form factor, the result obtained by following the same procedure
reads a_{mu}(LbyL;pi0)_{VMD} = +5.6 x 10^{-10}, and differs only by its overall
sign from the value obtained by previous authors. Inclusion of the eta and
eta-prime poles gives a total value a_{mu}(LbyL;PS) = +8.3 (1.2) x 10^{-10} for
the three pseudoscalar states. This result substantially reduces the difference
between the experimental value of a_{mu} and its theoretical counterpart in the
standard model.Comment: 27 pages, Latex, 3 figures. v2: version to be published in Phys. Rev.
D, Note added and references updated (don't worry, sign has not changed
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