3,918 research outputs found
The Pure State Space of Quantum Mechanics as Hermitian Symmetric Space
The pure state space of Quantum Mechanics is investigated as Hermitian
Symmetric Kaehler manifold. The classical principles of Quantum Mechanics
(Quantum Superposition Principle, Heisenberg Uncertainty Principle, Quantum
Probability Principle) and Spectral Theory of observables are discussed in this
non linear geometrical context.Comment: 18 pages, no figure
Indirect Searches for Dark Matter: a status review
I review in a schematic way the current status of indirect searches for Dark
Matter: I list the main relevant experimental results of the recent years and I
discuss the excitements and disappointments that their phenomenological
interpretations in terms of almost-standard annihilating Dark Matter have
brought along. I then try to individuate the main directions which have emerged
from the recent very intense model-building activity. In passing, I list the
main sources of uncertainties that affect this kind of searches.Comment: 32 pages, several figures. Extended version of the text for the
Proceedings of Lepton-Photon 2011, Mumbai. Comments and notifications of
inaccuracies, oversights or omissions are welcome (except on ref. [154]). v2:
refs added. v3: updated bounds and added short discussions of gamma-ray line
claims. (v4: just a couple of corrections in refs.) v5: more refs & details
added, updated neutrino bound
Updated galactic radio constraints on Dark Matter
We perform a detailed analysis of the synchrotron signals produced by Dark
Matter annihilations and decays. We consider different set-ups for the
propagation of electrons and positrons, the galactic magnetic field and Dark
Matter properties. We then confront these signals with radio and microwave
maps, including Planck measurements, from a frequency of 22 MHz up to 70 GHz.
We derive two sets of constraints: conservative and progressive, the latter
based on a modeling of the astrophysical emission. Radio and microwave
constraints are complementary to those obtained with other indirect detection
methods, especially for dark matter annihilating into leptonic channels.Comment: 20 pages, 10 figures. v2: some small additions, matches journal
versio
Multi-Component Dark Matter
We explore multi-component dark matter models where the dark sector consists
of multiple stable states with different mass scales, and dark forces coupling
these states further enrich the dynamics. The multi-component nature of the
dark matter naturally arises in supersymmetric models, where both R parity and
an additional symmetry, such as a , is preserved. We focus on a particular
model where the heavier component of dark matter carries lepton number and
annihilates mostly to leptons. The heavier component, which is essentially a
sterile neutrino, naturally explains the PAMELA, ATIC and synchrotron signals,
without an excess in antiprotons which typically mars other models of weak
scale dark matter. The lighter component, which may have a mass from a GeV to a
TeV, may explain the DAMA signal, and may be visible in low threshold runs of
CDMS and XENON, which search for light dark matter.Comment: 4 pages, no figures. v2: paper shortened to letter length; modified
dark matter spectru
Constraints on Dark Matter annihilations from reionization and heating of the intergalactic gas
Dark Matter annihilations after recombination and during the epoch of
structure formation deposit energy in the primordial intergalactic medium,
producing reionization and heating. We investigate the constraints that are
imposed by the observed optical depth of the Universe and the measured
temperature of the intergalactic gas. We find that the bounds are significant,
and have the power to rule out large portions of the `DM mass/cross section'
parameter space. The optical depth bound is generally stronger and does not
depend significantly on the history of structure formation. The temperature
bound can be competitive in some cases for small masses or the hadronic
annihilation channels (and is affected somewhat by the details of structure
formation). We find in particular that DM particles with a large annihilation
cross section into leptons and a few TeV mass, such as those needed to explain
the PAMELA and FERMI+HESS cosmic ray excesses in terms of Dark Matter, are
ruled out as they produce too many free electrons. We also find that low mass
particles (<~ 10 GeV) tend to heat too much the gas and are therefore
disfavored.Comment: 22 pages, 5 figures; v2: minor comments added, matches version
published on JCA
Supersymmetric Extension of the Minimal Dark Matter Model
The minimal dark matter model is given a supersymmetric extension. A super
SU(2)L quintuplet is introduced with its fermionic neutral component still
being the dark matter, the dark matter particle mass is about 19.7 GeV. Mass
splitting among the quintplet due to supersymmetry particles is found to be
negligibly small compared to the electroweak corrections. Other properties of
this supersymmetry model are studied, it has the solutions to the PAMELA and
Fermi-LAT anomaly, the predictions in higher energies need further experimental
data to verify.Comment: 14 pages, 7 figures, accepted for publication in Chinese Physics C,
typos correcte
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