83,182 research outputs found
The hierarchy problem and the cosmological constant problem in the Standard Model
We argue that the SM in the Higgs phase does not suffer form a "hierarchy
problem" and that similarly the "cosmological constant problem" resolves itself
if we understand the SM as a low energy effective theory emerging from a
cut-off medium at the Planck scale. We discuss these issues under the condition
of a stable Higgs vacuum, which allows to extend the SM up to the Planck
length. The bare Higgs boson mass then changes sign below the Planck scale,
such the the SM in the early universe is in the symmetric phase. The cut-off
enhanced Higgs mass term as well as the quartically enhanced cosmological
constant term trigger the inflation of the early universe. The coefficients of
the shift between bare and renormalized Higgs mass as well as of the shift
between bare and renormalized vacuum energy density exhibit close-by zeros at
some point below the Planck scale. The zeros are matching points between short
distance and the renormalized low energy quantities. Since inflation tunes the
total energy density to take the critical value of a flat universe
Omega_tot=rho_tot/rho_crit=Omega_Lambda+Omega_matter+Omega_radiation}=1 it is
obvious that Omega_Lambda today is of order Omega_tot given that
1>Omega_matter, Omega_radiation>0, which saturate the total density to about 26
% only, the dominant part being dark matter(21 %).Comment: 22 pages, 2 figure
Two powerful theorems in Clifford analysis
Two useful theorems in Euclidean and Hermitean Clifford analysis are discussed: the Fischer decomposition and the Cauchy-Kovalevskaya extension
Apophatic Community: Yannaras on Relational Being
For Martin Heidegger the story of Western philosophy ended basically in egocentrism or the metaphysics of “subjectivity”; however, he acknowledged the possibility of another path in Greece: that of pre-Socratic thinking. Yet, there is a further path he did not acknowledge: the tradition of Orthodox philosophy and theology. The paper focuses on some key works of the prominent contemporary Greek philosopher Christos Yannaras, for a long time professor in Athens. Taking over the notions of “Being” and ontology, Yannaras construes them (with Heidegger) not as ontic “substances” amenable to epistemic knowledge, but as guideposts to “relational” or participatory experience. His early text On the Absence and Unknowability of God: Heidegger and the Aeropagite explores the (at least partial) affinity between the German thinker and the Orthodox stress on “apophaticism.” For Yannaras, apophaticism profoundly reorients philosophical inquiry; it also has important implications for human “personhood” and “freedom.” Far from denoting individuation, personhood for him means a face (prosopon) standing out toward others, just as freedom transcends self-will in the direction of a relational event. By way of conclusion, I probe the status of relational “community.” For Yannaras, I ask, is community a concretely achieved way of life (exemplified by the Orthodox Church); or does it point more apophatically (and prophetically) to a future advent
Higgs inflation and the cosmological constant
The Higgs not only induces the masses of all SM particles, the Higgs, given
its special mass value, is the natural candidate for the inflaton and in fact
is ruling the evolution of the early universe, by providing the necessary dark
energy which remains the dominant energy density. SM running couplings not only
allow us to extrapolate SM physics up to the Planck scale, but equally
important they are triggering the Higgs mechanism. This is possible by the fact
that the bare mass term in the Higgs potential changes sign at about mu_0 =
1.4x10^16 GeV and in the symmetric phase is enhanced by quadratic terms in the
Planck mass. Such a huge Higgs mass term is able to play a key role in
triggering inflation in the early universe. In this article we extend our
previous investigation by working out the details of a Higgs inflation
scenario. We show how different terms contributing to the Higgs Lagrangian are
affecting inflation. Given the SM and its extrapolation to scales mu>mu_0 we
find a calculable cosmological constant V(0) which is weakly scale dependent
and actually remains large during inflation. This is different to the Higgs
fluctuation field dependent Delta V(phi), which decays exponentially during
inflation, and actually would not provide a sufficient amount of inflation. The
fluctuation field has a different effective mass which shifts the bare Higgs
transition point to a lower value mu'_0 = 7.7x10^14 GeV. The vacuum energy V(0)
being proportional to M_Pl^4 has a coefficient which vanishes near the Higgs
transition point, such that the bare and the renormalized cosmological constant
match at this point. The role of the Higgs in reheating and baryogenesis is
emphasized.Comment: 39 pages, 25 figures, 1 table. Replacement: typos corrected, Eq (3)
corrected, notation adjuste
People's perception of malaria in Mbarara, Uganda.
To understand people's perceptions of malaria and their implications for control programmes, we held focus group discussions (FGDs) and conducted semi-structured interviews (SSIs) with community members in Mbarara, Uganda. Mosquitoes were perceived as the cause or transmitters of malaria but the causation/transmission model of people differed from biomedical facts. Convulsions, a common complication of malaria, were perceived as a supernatural ailment, best treated by traditional medicine, as was splenomegaly. More than 70% of the patients with malaria had treatment from non-public health sources. This included self-treatment (13%), use of traditional healers (12%) and use of private medical practitioners/pharmacists (69%). Although 26% (887/3309) used bednets to prevent malaria, only 7% of the nets were impregnated with insecticide. People who did not use bednets cited discomfort because of heat/humidity and their high cost as reasons. To improve malaria control in this area, people need to be educated on the connection between mosquitoes and malaria and on seeking biomedical treatment for convulsions. The malaria control programme could collaborate with traditional and private health care providers to increase promotion of insecticide-impregnated mosquito nets
About the role of the Higgs boson in the evolution of the early universe
After the discovery of the Higgs particle the most relevant structures of the
SM have been verified and for the first time we know all parameters of the SM
within remarkable accuracy. Together with recent calculations of the SM
renormalization group coefficients up to three loops we can safely extrapolate
running couplings high up in energy. Assuming that the SM is a low energy
effective theory of a cutoff theory residing at the Planck scale, we are able
to calculate the effective bare parameters of the underlying cutoff system. It
turns out that the effective bare mass term changes sign not far below the
Planck scale, which means that in the early universe the SM was in the
symmetric phase. The sign-flip, which is a result of a conspiracy between the
SM couplings and their screening/antiscreening behavior, triggers the Higgs
mechanism. Above the Higgs phase transition the bare mass term in the Higgs
potential must have had a large positive value, enhanced by the quadratic
divergence of the bare Higgs mass. Likewise the quartically enhanced positive
vacuum energy density is present in the symmetric phase. The Higgs system thus
provides the large dark energy density in the early universe, which triggers
slow-roll inflation, i.e. the SM Higgs is the inflaton scalar field. Reheating
is dominated by the decay of the heavy Higgses into (in the symmetric phase)
massless top/anti-top quark pairs. The new scenario possibly could explain the
baryon-asymmetry essentially in terms of SM physicsComment: 19 pages, 6 figure
Variations on Photon Vacuum Polarization
I provide updates for the theoretical predictions of the muon and electron
anomalous magnetic moments, for the shift in the fine structure constant
and for the weak mixing parameter .
Phenomenological results for Euclidean time correlators, the key objects in the
lattice QCD approach to hadronic vacuum polarization, are briefly considered.
Furthermore, I present a list of isospin breaking and electromagnetic
corrections for the lepton moments, which may be used to supplement lattice QCD
results obtained in the isospin limit and without the e.m. corrections.Comment: 10 pages, 4 figure
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