20,442 research outputs found
Massless fermions in multi-flavor QED_2
The ground state of the multi-flavor 2-dimensional quantum electrodynamics
(QED_2) is determined in the presence of finite baryon density, and it is shown
that the model possesses two phases, the low density phase where the external
baryon density is totally screened, and the high density phase, where the
screening is only partial. The renormalization of the bosonized version of the
model is also performed for both the zero and the finite density model giving
massless multi-flavor QED_2 in both cases.Comment: 12 pages, 6 figures, published in Phys. Rev.
Utilizing Community Resources to Reduce the Presence of Type 2 Diabetes in Rural Youth
The purpose of this study was to implement a program designed to promote diabetes prevention activities among preadolescents in a rural southern setting using a day camp intervention. Participants in the study were eleven youth from a rural Alabama county who participated in a week-long half-day camp administered by local and community volunteers. Change scores were used to compare pre- to post- to follow-up measures for camp participant responses. Program results consistently demonstrated that the day camp was theoretically sound and that program activities positively impacted behavioral antecedents. This study demonstrated the feasibility of conducting a diabetes prevention day camp in a rural environment. Insights from this intervention can assist planners in rural environments to tailor similar initiatives in rural settings. Given the complicated nature of behavior change, a day camp approach of this length does not modify the behaviors of participants. Behavior changes may take considerably longer to initiate
Cryogenic mirror analysis
Due to extraordinary distances scanned by modern telescopes, optical surfaces in such telescopes must be manufactured to unimaginable standards of perfection of a few thousandths of a centimeter. The detection of imperfections of less than 1/20 of a wavelength of light, for application in the building of the mirror for the Space Infrared Telescope Facility, was undertaken. Because the mirror must be kept very cold while in space, another factor comes into effect: cryogenics. The process to test a specific morror under cryogenic conditions is described; including the follow-up analysis accomplished through computer work. To better illustrate the process and analysis, a Pyrex Hex-Core mirror is followed through the process from the laser interferometry in the lab, to computer analysis via a computer program called FRINGE. This analysis via FRINGE is detailed
Renormalization of the bilocal sine-Gordon model
The functional renormalization group treatment is presented for the
two-dimensional sine-Gordon model by including a bilocal term in the potential,
which contributes to the flow at tree level. It is shown that the flow of the
bilocal term can substitute the evolution of the wave function renormalization
constant, and then the Kosterlitz-Thouless type phase transition can be
recovered.Comment: 16 pages, 2 figure
Functional renormalization group for quantized anharmonic oscillator
Functional renormalization group methods formulated in the real-time
formalism are applied to the symmetric quantum anharmonic oscillator,
considered as a dimensional quantum field-theoric model, in the
next-to-leading order of the gradient expansion of the one- and two-particle
irreducible effective action. The infrared scaling laws and the
sensitivity-matrix analysis show the existence of only a single, symmetric
phase. The field-independent term of the wavefunction renormalization turned
out to be negligible, but its field-dependent piece is noticeable. It is shown
that the infrared limits of the running couplings depend on the renormalization
group scheme used, when the perturbation expansion in the bare quartic coupling
is truncated keeping the terms up to the second order.Comment: 30 pages, 11 figure
Some consequences of GUP induced ultraviolet wavevector cutoff in one-dimensional Quantum Mechanics
A projection method is proposed to treat the one-dimensional Schrodinger
equation for a single particle when the Generalized Uncertainty Principle (GUP)
generates an ultraviolet (UV) wavevector cutoff. The existence of a unique
coordinate representation called the naive one is derived from the
one-parameter family of discrete coordinate representations. In this
bandlimited Quantum Mechanics a continuous potential is reconstructed from
discrete sampled values observed by means of a particle in maximally localized
states. It is shown that bandlimitation modifies the speed of the center and
the spreading time of a Gaussian wavepacket moving in free space. Indication is
found that GUP accompanied by bandlimitation may cause departures of the
low-lying energy levels of a particle in a box from those in ordinary Quantum
Mechanics much less suppressed than commonly thought when GUP without
bandlimitation is in work.Comment: 20 pages, 2 figure
Asymptotic safety in the sine-Gordon model
In the framework of the functional renormalization group method it is shown
that the phase structure of the 2-dimensional sine-Gordon model possesses a
nontrivial UV fixed point which makes the model asymptotically safe. The fixed
point exhibits strong singularity similarly to the scaling found in the
vicinity of the infrared fixed point. The singularity signals the upper
energy-scale limit to the validity of the model. We argue that the sine-Gordon
model with a momentum-dependent wavefunction renormalization is in a dual
connection with the massive sine-Gordon model.Comment: 8 pages, 3 figure
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