39 research outputs found
Bayesian inference with information content model check for Langevin equations
The Bayesian data analysis framework has been proven to be a systematic and
effective method of parameter inference and model selection for stochastic
processes. In this work we introduce an information content model check which
may serve as a goodness-of-fit, like the chi-square procedure, to complement
conventional Bayesian analysis. We demonstrate this extended Bayesian framework
on a system of Langevin equations, where coordinate dependent mobilities and
measurement noise hinder the normal mean squared displacement approach.Comment: 10 pages, 7 figures, REVTeX, minor revision
Four-Fermion Limit of Gauge-Yukawa Theories
We elucidate and extend the conditions that map gauge-Yukawa theories at low
energies into time-honoured gauged four-fermion interactions at high energies.
These compositeness conditions permit to investigate theories of composite
dynamics through gauge-Yukawa theories. Here we investigate whether
perturbative gauge-Yukawa theories can have a strongly coupled limit at
high-energy, that can be mapped into a four-fermion theory. Interestingly, we
are able to precisely carve out a region of the perturbative parameter space
supporting such a composite limit. This has interesting implications on our
current view on models of particle physics. As a template model we use an
gauge theory with Dirac fermions transforming according to the
fundamental representation of the gauge group. The fermions further interact
with a gauge singlet complex Higgs that ceases to be a physical
degree of freedom at the ultraviolet composite scale, where it gives away to
the four-fermion interactions. We compute the hierarchy between the ultraviolet
and infrared composite scales of the theory and show that they are naturally
large and well separated. Our results show that some weakly coupled
gauge-Yukawa theories can be viewed, in fact, as composite theories. It is
therefore tantalising to speculate that the standard model, with its
phenomenological perturbative Higgs sector, could hide, in plain sight, a
composite theory.Comment: 20 pages, 9 figures, 10 pages Appendix, corrected typos and reference
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Stable Extensions with(out) Gravity
We investigate the vacuum stability as well as the gravitational corrections
in extensions of the Standard Model featuring a new complex scalar, and two
Dirac fermions for different choices of the hypercharge of the scalar and one
of the two fermions. The neutral fermion acquires loop-induced magnetic
interactions with the Standard Model and could be identified with a dark matter
candidate. To the lowest order in perturbation theory we show that these
extensions can save the electroweak vacuum from being metastable. We then add
the gravitational corrections to the different beta functions and discover that
the models can be compatible with the asymptotically safe gravity scenario at
the price of a heavier Higgs and lighter top mass.Comment: 12 pages, 4 figure
Standard Model-like corrections to Dilatonic Dynamics
We examine the effects of standard model-like interactions on the
near-conformal dynamics of a theory featuring a dilatonic state identified with
the standard model-like Higgs. As template for near-conformal dynamics we use a
gauge theory with fermionic matter and elementary mesons possessing the same
non-abelian global symmetries as a technicolor-like theory with matter in a
complex representation of the gauge group. We then embed the electroweak gauge
group within the global flavor structure and add also ordinary quark-like
states to mimic the effects of the top. We find that the standard model-like
induced corrections modify the original phase diagram and the details of the
dilatonic spectrum. In particular, we show that the corrected theory exhibits
near-conformal behavior for a smaller range of flavors and colors. For this
range of values, however, our results suggest that near conformal dynamics
could accommodate the observed Higgs-like properties.Comment: 15 pages, 8 figure
Trainability of cold induced vasodilatation in fingers and toes
Subjects that repeatedly have to expose the extremities to cold may benefit from a high peripheral temperature to maintain dexterity and tissue integrity. Therefore, we investigated if repeated immersions of a hand and a foot in cold water resulted in increased skin temperatures. Nine male and seven female subjects (mean 20.4; SD 2.2 years) immersed their right (trained) hand and foot simultaneously in 8°C water, 30 min daily for 15 days. During the pre and post-test (days 1 and 15, respectively) the left (untrained) hand and foot were immersed as well. Pain, tactile sensitivity and skin temperatures were measured every day. Mean (SD) toe temperature of the trained foot increased from 9.49°C (0.89) to 10.03°C (1.38) (p < 0.05). The trained hand, however, showed a drop in mean finger temperature from 9.28°C (0.54) to 8.91°C (0.44) (p < 0.001) and the number of cold induced vasodilation (CIVD) reactions decreased from 52% during the first test to 24% during the last test. No significant differences occurred in the untrained extremities. Pain diminished over time and tactile sensitivity decreased with skin temperature. The combination of less CIVD responses in the fingers after training, reduced finger skin temperatures in subjects that did show CIVD and the reduced pain and tactile sensitivity over time may lead to an increased risk for finger cold injuries. It is concluded that repeated cold exposure of the fingers does not lead to favorable adaptations, but may instead increase the injury risk