Mossbauer neutrinos in quantum mechanics and quantum field theory

We demonstrate the correspondence between quantum mechanical and quantum field theoretical descriptions of Mossbauer neutrino oscillations. First, we compute the combined rate $\Gamma$ of Mossbauer neutrino emission, propagation, and detection in quantum field theory, treating the neutrino as an internal line of a tree level Feynman diagram. We include explicitly the effect of homogeneous line broadening due to fluctuating electromagnetic fields in the source and detector crystals and show that the resulting formula for $\Gamma$ is identical to the one obtained previously (Akhmedov et al., arXiv:0802.2513) for the case of inhomogeneous line broadening. We then proceed to a quantum mechanical treatment of Mossbauer neutrinos and show that the oscillation, coherence, and resonance terms from the field theoretical result can be reproduced if the neutrino is described as a superposition of Lorentz-shaped wave packet with appropriately chosen energies and widths. On the other hand, the emission rate and the detection cross section, including localization and Lamb-Mossbauer terms, cannot be predicted in quantum mechanics and have to be put in by hand.Comment: LaTeX, 16 pages, 1 figure; v2: typos corrected; matches published versio

The Littlest Higgs

We present an economical theory of natural electroweak symmetry breaking, generalizing an approach based on deconstruction. This theory is the smallest extension of the Standard Model to date that stabilizes the electroweak scale with a naturally light Higgs and weakly coupled new physics at TeV energies. The Higgs is one of a set of pseudo Goldstone bosons in an $SU(5)/SO(5)$ nonlinear sigma model. The symmetry breaking scale $f$ is around a TeV, with the cutoff \Lambda \lsim 4\pi f \sim 10 TeV. A single electroweak doublet, the ``little Higgs'', is automatically much lighter than the other pseudo Goldstone bosons. The quartic self-coupling for the little Higgs is generated by the gauge and Yukawa interactions with a natural size $O(g^2,\lambda_t^2)$, while the top Yukawa coupling generates a negative mass squared triggering electroweak symmetry breaking. Beneath the TeV scale the effective theory is simply the minimal Standard Model. The new particle content at TeV energies consists of one set of spin one bosons with the same quantum numbers as the electroweak gauge bosons, an electroweak singlet quark with charge 2/3, and an electroweak triplet scalar. One loop quadratically divergent corrections to the Higgs mass are cancelled by interactions with these additional particles.Comment: 15 pages. References added. Corrected typos in the discussion of the top Yukawa couplin

The Minimal Moose for a Little Higgs

Recently a new class of theories of electroweak symmetry breaking have been constructed. These models, based on deconstruction and the physics of theory space, provide the first alternative to weak-scale supersymmetry with naturally light Higgs fields and perturbative new physics at the TeV scale. The Higgs is light because it is a pseudo-Goldstone boson, and the quadratically divergent contributions to the Higgs mass are cancelled by new TeV scale ``partners'' of the {\em same} statistics. In this paper we present the minimal theory space model of electroweak symmetry breaking, with two sites and four link fields, and the minimal set of fermions. There are very few parameters and degrees of freedom beyond the Standard Model. Below a TeV, we have the Standard Model with two light Higgs doublets, and an additional complex scalar weak triplet and singlet. At the TeV scale, the new particles that cancel the 1-loop quadratic divergences in the Higgs mass are revealed. The entire Higgs potential needed for electroweak symmetry breaking--the quartic couplings as well as the familiar negative mass squared--can be generated by the top Yukawa coupling, providing a novel link between the physics of flavor and electroweak symmetry breaking.Comment: 15 pages. References added. Included clarifying comments on the origin of quartic couplings, and on power-counting. More elegant model for generating Higgs potential from top Yukawa coupling presente

New Strong Interactons at the Tevatron ?

Recent results from CDF indicate that the inclusive cross section for jets with $E_T > 200$ GeV is significantly higher than that predicted by QCD. We describe here a simple flavor-universal variant of the ``coloron" model of Hill and Parke that can accommodate such a jet excess, and which is not in contradiction with other experimental data. As such, the model serves as a useful baseline with which to compare both the data and other models proposed to describe the jet excess. An interesting theoretical feature of the model is that if the global chiral symmetries of the quarks remain unbroken in the confining phase of the coloron interaction, it realizes the possibility that the ordinary quarks are composite particles.Comment: added $1/Lambda^4$ contributions to scattering cross-sections; 10 pages, LaTeX, includes 1 figure. Full postscript version at http://smyrd.bu.edu/htfigs/htfigs.htm

Going higher in the First-order Quantifier Alternation Hierarchy on Words

We investigate the quantifier alternation hierarchy in first-order logic on finite words. Levels in this hierarchy are defined by counting the number of quantifier alternations in formulas. We prove that one can decide membership of a regular language to the levels $\mathcal{B}\Sigma_2$ (boolean combination of formulas having only 1 alternation) and $\Sigma_3$ (formulas having only 2 alternations beginning with an existential block). Our proof works by considering a deeper problem, called separation, which, once solved for lower levels, allows us to solve membership for higher levels

THE TIGHT-BINDING APPROACH TO THE DIELECTRIC RESPONSE IN THE MULTIBAND SYSTEMS

Starting from the random phase approximation for the weakly coupled multiband tightly-bounded electron systems, we calculate the dielectric matrix in terms of intraband and interband transitions. The advantages of this representation with respect to the usual plane-wave decomposition are pointed out. The analysis becomes particularly transparent in the long wavelength limit, after performing the multipole expansion of bare Coulomb matrix elements. For illustration, the collective modes and the macroscopic dielectric function for a general cubic lattice are derived. It is shown that the dielectric instability in conducting narrow band systems proceeds by a common softening of one transverse and one longitudinal mode. Furthermore, the self-polarization corrections which appear in the macroscopic dielectric function for finite band systems, are identified as a combined effect of intra-atomic exchange interactions between electrons sitting in different orbitals and a finite inter-atomic tunneling.Comment: 20 pages, LaTeX, no figure

Purpose and enactment in job design: An empirical examination of the processes through which job characteristics have their effects

Job characteristics are linked with health, safety, well-being and other performance outcomes. Job characteristics are usually assessed by their presence or absence, which gives no indication of the specific purposes for which workers might use some job characteristics. We focused on job control and social support as two job characteristics embedded in the well-known Demand-Control-Support model (Karasek & Theorell, 1990). In Study 1, using an experience sampling methodology (N = 67) and a cross-sectional survey methodology (N = 299), we found that relationships between the execution of job control or the elicitation of social support and a range of other variables depended on the purposes for which job control was executed or social support elicited. In Study 2 (N = 28), we found that it may be feasible to improve aspects of well-being and performance through training workers on how to use job control or social support for specific purposes

An Extended Technicolor Model

An extended technicolor model is constructed. Quark and lepton masses, spontaneous CP violation, and precision electroweak measurements are discussed. Dynamical symmetry breaking is analyzed using the concept of the BIG MAC.Comment: 35 pages, Latex, YCTP-P21-93, BUHEP-93-2

Reversible Random Sequential Adsorption of Dimers on a Triangular Lattice

We report on simulations of reversible random sequential adsorption of dimers on three different lattices: a one-dimensional lattice, a two-dimensional triangular lattice, and a two-dimensional triangular lattice with the nearest neighbors excluded. In addition to the adsorption of particles at a rate K+, we allow particles to leave the surface at a rate K-. The results from the one-dimensional lattice model agree with previous results for the continuous parking lot model. In particular, the long-time behavior is dominated by collective events involving two particles. We were able to directly confirm the importance of two-particle events in the simple two-dimensional triangular lattice. For the two-dimensional triangular lattice with the nearest neighbors excluded, the observed dynamics are consistent with this picture. The two-dimensional simulations were motivated by measurements of Ca++ binding to Langmuir monolayers. The two cases were chosen to model the effects of changing pH in the experimental system.Comment: 9 pages, 10 figure

The visual, the auditory and the haptic – A user study on combining modalities in virtual worlds

Fröhlich J, Wachsmuth I. The visual, the auditory and the haptic – A user study on combining modalities in virtual worlds. In: Shumaker R, ed. Virtual Augmented and Mixed Reality. Designing and Developing Augmented and Virtual Environments. Lecture Notes in Computer Science. Vol 8021. Berlin, Heidelberg: Springer Berlin Heidelberg; 2013: 159-168.In order to make a step further towards understanding the impact of multi-modal stimuli in Virtual Reality we conducted a user study with 80 participants performing tasks in a virtual pit environment. Participants were divided into four groups, each presented a different combination of multi-sensory stimuli. Those included real-time 3D graphics, audio stimuli (ambient, static and event sounds), and haptics consisting of wind and tactile feedback when touching objects. A presence questionnaire was used to evaluate subjectively reported presence on the one hand, and on the other physiological sensors were used to measure heart rate and skin conductance as an objective measure. Results strongly indicate that an increase of modalities does not automatically result in an increase of presence