32,597 research outputs found
Relic abundance of dark matter particles: new formulation and new result of abundance calculation
A new theoretical framework for computation of the relic abundance of cold
dark matter particles such as LSP is presented and some generic features of new
results are discussed. The most important is a generalization of the Boltzmann
equation to include off-shell effects and its thermal average over cosmic
medium. It is shown that at very low temperatures, much below the mass of
annihilating particles, equilibrium abundance is suppressed only by powers of
temperature instead of the exponential Boltzmann factor. This change gives a
larger relic abundance when heavy particles freeze out at these low
temperatures.Comment: 7 pages, LATEX file. Talk given at COSMO9
Towards Resolution of Hierarchy Problems in a Cosmological Context
A cosmological scenario is proposed, which simultaneously solves the mass
hierarchy and the small dark energy problem. In the present scenario an
effective gravity mass scale (inverse of the Newton's constant) increases
during the inflationary period. The small cosmological constant or the dark
energy density in the present universe is dynamically realized by introducing
two, approximately O(2) symmetric dilatons, taking the fundamental mass scale
at TeV.Comment: 12 pages, no figur
Collision rate ansatz for quantum integrable systems
For quantum integrable systems the currents averaged with respect to a
generalized Gibbs ensemble are revisited. An exact formula is known, which we
call "collision rate ansatz". While there is considerable work to confirm this
ansatz in various models, our approach uses the symmetry of the current-charge
susceptibility matrix, which holds in great generality. Besides some technical
assumptions, the main input is the availability of a self-conserved current,
i.e. some current which is itself conserved. The collision rate ansatz is then
derived. The argument is carried out in detail for the Lieb-Liniger model and
the Heisenberg XXZ chain. The Fermi-Hubbard model is not covered, since no
self-conserved current seems to exist. It is also explained how from the
existence of a boost operator a self-conserved current can be deduced.Comment: v1: 14 pages, v2: 15 pages, references added, typos corrected, v3: 17
pages, references added, explanations improved, an appendix on the collision
rate ansatz for generalized currents is supplemente
New method of galactic axion search
An appealing candidate of the galactic dark matter is the axion, which was
postulated to solve the strong CP (Charge-conjugation Parity) violation problem
in the standard particle theory. A new experimental method is proposed to
determine the axion mass. The method uses collectively and coherently excited
atoms or molecules, the trigger laser inducing galactic axion absorption along
with signal photon emission to be detected.Comment: Finite size effect of target is incorporated. 5 pages, 3 figure
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