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Search Results: 1 - 10 of 297884 matches for " J. Hansson "
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The "Proton Spin Crisis" - a Quantum Query
Hansson J.
Progress in Physics , 2010,
Abstract: The "proton spin crisis" was introduced in the late 1980s, when the EMC-experiment revealed that little or nothing of a proton's spin seemed to be carried by its quarks. The main objective of this paper is to point out that it is wrong to assume that the proton spin, as measured by completely different experimental setups, should be the same in all circumstances, an assumption explicitly made in all present theoretical treatments of the "crisis". As spin is a genuine quantum property, without any objective existence outside its measuring apparatus context, proper account of quantum mechanical measurement theory must be taken.
Meat production from moose
J Hansson, G Malmfors
Genetics Selection Evolution , 1978, DOI: 10.1186/1297-9686-10-4-600a
The observational legacy of preon stars - probing new physics beyond the LHC
Sandin, F.;Hansson, J.
High Energy Physics - Phenomenology , 2007, DOI: 10.1103/PhysRevD.76.125006
Abstract: We discuss possible ways to observationally detect the superdense cosmic objects composed of hypothetical sub-constituent fermions beneath the quark/lepton level, recently proposed by us. The characteristic mass and size of such objects depend on the compositeness scale, and their huge density cannot arise within a context of quarks and leptons alone. Their eventual observation would therefore be a direct vindication of physics beyond the standard model of particle physics, possibly far beyond the reach of the Large Hadron Collider (LHC), in a relatively simple and inexpensive manner. If relic objects of this type exist, they can possibly be detected by present and future x-ray observatories, high-frequency gravitational wave detectors, and seismological detectors. To have a realistic detection rate, i.e., to be observable, they must necessarily constitute a significant fraction of cold dark matter.
Preon stars: a new class of cosmic compact objects
J. Hansson,F. Sandin
Physics , 2004, DOI: 10.1016/j.physletb.2005.04.034
Abstract: In the context of the standard model of particle physics, there is a definite upper limit to the density of stable compact stars. However, if a more fundamental level of elementary particles exists, in the form of preons, stability may be re-established beyond this limiting density. We show that a degenerate gas of interacting fermionic preons does allow for stable compact stars, with densities far beyond that in neutron stars and quark stars. In keeping with tradition, we call these objects "preon stars", even though they are small and light compared to white dwarfs and neutron stars. We briefly note the potential importance of preon stars in astrophysics, e.g., as a candidate for cold dark matter and sources of ultra-high energy cosmic rays, and a means for observing them.
A Coherent State Path Integral for Anyons
J. Grundberg,T. H. Hansson
Physics , 1994, DOI: 10.1142/S0217732395001083
Abstract: We derive an $su(1,1)$ coherent state path integral formula for a system of two one-dimensional anyons in a harmonic potential. By a change of variables we transform this integral into a coherent states path integral for a harmonic oscillator with a shifted energy. The shift is the same as the one obtained for anyons by other methods. We justify the procedure by showing that the change of variables corresponds to a $su(1,1)$ version of the Holstein-Primakoff transformation.
The QCD Trace Anomaly as a Vacuum Effect (The vacuum is a medium is the message!)
J. Grundberg,T. H. Hansson
Physics , 1994, DOI: 10.1006/aphy.1995.1086
Abstract: We use arguments taken from the electrodynamics of media to deduce the QCD trace anomaly from the expression for the vacuum energy in the presence of an external color magnetic field.
Educational Activities at the Sami Folk High School 1942-1982  [PDF]
Johan Hansson
Creative Education (CE) , 2015, DOI: 10.4236/ce.2015.69090
Abstract: The Sami folk high school started in 1942 as a school for young Sami that needed more education that the Swedish folk school or nomadic school offered its pupils. The school was managed by the Swedish mission society, an organization within the Swedish church. The school was successful but struggled with financial problems. The result was that a foundation with Sami representation managed the school instead after 1972. The following year was even more successful. The number of students increased, and the management could offer more courses and their curriculum had more Sami elements than earlier. However, there was also some conflicts during the 1970s. The largest one being the language boycott addressing the issue of Sami languages at the Sami folk high school as a subject in the school, and as an important part of the Sami culture and identity. This article describes the education of the Sami folk high school’s first 40 years with the help of a model for Sami pedagogy developed by Keskitalo and Määttä. The model shows that the education is to a large extent affected by outer factors—self determination, as well as inner factors—language issues and the curriculum.
Quasihole condensates in quantum Hall liquids
J. Suorsa,S. Viefers,T. H. Hansson
Physics , 2010, DOI: 10.1103/PhysRevB.83.235130
Abstract: We develop a formalism to describe quasihole condensates in quantum Hall liquids and thereby extend the conformal field theory approach to the full hierarchy of spin-polarized Abelian states, and to several classes of non-Abelian hierarchical states. Most previously proposed spin-polarized quantum Hall wave functions appear as special cases. In this paper we explain the physical motivations for the approach, and exemplify it by explicitly constructing the level-two quasihole condensate state at filling fraction 2/3, and the two level-three states at 5/13 and 5/7 which are built from combinations of quasielectron and quasihole condensates.
TeV Neutrinos in a dense medium
A. Nicolaidis,G. Tsirigoti,J. Hansson
Physics , 1999,
Abstract: The dispersion relation of energetic (few TeV) neutrinos traversing a medium is studied. We use the real time formalism of thermal field theory and we include the effects from the propagator of the W gauge boson. We consider then the MSW oscillations for cosmic neutrinos traversing the Earth, adopting for the neutrino parameters values suggested by the LSND results. It is found that the $\nu_\mu$ flux, for neutrinos passing through the center of the Earth, will appear reduced by 15% for energies around 10 TeV.
Charge and Current in the Quantum Hall Matrix Model
T. H. Hansson,J. Kailasvuori,A. Karlhede
Physics , 2003, DOI: 10.1103/PhysRevB.68.035327
Abstract: We extend the quantum Hall matrix model to include couplings to external electric and magnetic fields. The associated current suffers from matrix ordering ambiguities even at the classical level. We calculate the linear response at low momenta -- this is unambigously defined. In particular, we obtain the correct fractional quantum Hall conductivity, and the expected density modulations in response to a weak and slowly varying magnetic field. These results show that the classical quantum Hall matrix models describe important aspects of the dynamics of electrons in the lowest Landau level. In the quantum theory the ordering ambiguities are more severe; we discuss possible strategies, but we have not been able to construct a good density operator, satisfying the pertinent lowest Landau level commutator algebra.
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