70,775 research outputs found
First record of a white rough-toothed dolphin (Steno bredanensis) off West Africa including notes on rough-toothed dolphin surface behaviour
In June 2009, a white rough-toothed dolphin (Steno bredanensis) calf was photographed in a group of at least 50 dolphins in the southern Gulf of Guinea, 95 nauticol miles off the Gabon coast (01°45'S 007°29'E), West Africa. Reports of unusually pigmented cetaceans are infrequent and this record represents the first of an all-white rough-toothed dolphin. Furthermore, there is little documentation concerning rough-toothed dolphins and this note contributes to the knowledge of this species in tropical West African water
Anomalous internal pair conversion signaling elusive light neutral particles
In this paper we report on a systematic search for a neutral boson in the
mass range between 5 and 15 MeV/c in the decay of highly excited nuclei.
Its signature is found a deviation in the angular correlation of the
pairs from conventional internal pair conversion (IPC) resulting from of its
two-body decay kinematics. With an pair-spectrometer, a number of
transitions has been investigated in the
--nuclei Be, C and O, following light ion
induced reactions at low bombarding energies, first at IKF in Frankfurt and
during the last years at ATOMKI in Debrecen. Startlingly, in all isoscalar
transitions excess pairs are found at large angles with branching
ratios with respect to the total yield ranging from 10 to 10. If
these deviations are all related to the two-body decay of an -boson, this
observation implies plural -bosons. An analysis of all angular spectra with
a boson search program, yields a pandemonium of more than ten candidate bosons.Comment: 7 pages, 2 figures, contributed paper to the Int. Symposium on Exotic
Nuclear Systems (ENS05), ATOMKI, Debrecen, Hungary, 20-25 June 200
The Discovery of the Higgs Boson with the CMS Detector and its Implications for Supersymmetry and Cosmology
The discovery of the long awaited Higgs boson is described using data from
the CMS detector at the LHC. In the SM the masses of fermions and the heavy
gauge bosons are generated by the interactions with the Higgs field, so all
couplings are related to the observed masses. Indeed, all observed couplings
are consistent with the predictions from the Higgs mechanism, both to vector
bosons and fermions implying that masses are indeed consistent of being
generated by the interactions with the Higgs field. However, on a cosmological
scale the mass of the universe seems not to be related to the Higgs field: the
baryonic mass originates from the binding energy of the quarks inside the
nuclei and dark matter is not even predicted in the SM, so the origin of its
mass is unknown. The dominant energy component in the universe, the dark
energy, yields an accelerated expansion of the universe, so its repulsive
gravity most likely originates from a kind of vacuum energy. The Higgs field
would be the prime candidate for this, if the energy density would not be many
orders of magnitude too high, as will be calculated. The Higgs mass is found to
be 125.70.3(stat.)0.3(syst.) GeV, which is below 130 GeV, i.e. in the
range predicted by supersymmetry. This may be the strongest hint for
supersymmetry in spite of the fact that the predicted supersymmetric particles
have not been discovered so far.Comment: 26 pages, Conference Proceedings Time and Matter (TAM2013), Venice,
Feb. 201
A new Determination of the Extragalactic Background of Diffuse Gamma Rays taking into account Dark Matter Annihilation
The extragalactic background (EGB) of diffuse gamma rays can be determined by
subtracting the Galactic contribution from the data. This requires a Galactic
model (GM) and we include for the first time the contribution of dark matter
annihilation (DMA), which was previously proposed as an explanation for the
EGRET excess of diffuse Galactic gamma rays above 1 GeV.
In this paper it is shown that the newly determined EGB shows a
characteristic high energy bump on top of a steeply falling soft contribution.
The bump is shown to be compatible with a contribution from an extragalactic
DMA signal from weakly interacting massive particles (WIMPs) with a mass
between 50 and 100 GeV in agreement with the EGRET excess of the Galactic
diffuse gamma rays and in disagreement with earlier analysis. The remaining
soft contribution of the EGB is shown to resemble the spectra of the observed
point sources in our Galaxy.Comment: 7 pages, 4 figures. Accepted by A&A, made Fig. 4 and table 1
consisten
Perspectives on the detection of supersymmetric Dark Matter
Up to now searches for Dark Matter (DM) detection have not been successful,
either because our paradigm in how DM signals should look like are wrong or the
detector sensitivity is still too low in spite of the large progress made in
recent years. We discuss both possibilities starting with what we know about DM
from cosmology and why Supersymmetry provides such an interesting paradigm for
cosmology and particle physics in order to appreciate what it means to give up
this paradigm. In addition, we compare the predicted cross sections for direct
and indirect DM detection with observations with emphasis on the latest
developments. Especially, we discuss the possible origins of the two hotly
debated candidates for a DM annihilation signal, namely the positron excess and
the Fermi GeV excess, which are unfortunately incompatible with each other and
more mundane astrophysical explanations exist.Comment: 18 pages, 12 figures. Invited talk at ICNFP2017, August 2017, Crete,
Greec
Indirect Dark Matter Searches in the Light of ATIC, FERMI, EGRET and PAMELA
Recently, new data on antiprotons and positrons from PAMELA, e- + e+ spectra
from ATIC, FERMI and HESS up to TeV energies all indicate deviations from
expectations, which has caused an interesting mix of new explanations, ranging
from background, standard astrophysical sources to signals from dark matter
(DM) annihilation. Unfortunately, the excess in positrons is not matched with
obvious excesses in antiprotons or gamma rays, so a new class of DM scenarios
with leptophilic WIMP candidates have been invoked. On the other hand, the
increase in the positron fraction, which could have had any spectral shape for
new physics, matches well the shape expected from proton background.Comment: Invited talk at SUSY09, the 17th International Conference on
Supersymmetry and the Unification of Fundamental Interactions, Boston, 200
- …