Search Publications
Reducing the tension between the BICEP2 and the Planck measurements: A complete exploration of the parameter space
Lu, You-Jun; Li, Yi-Chao; Wu, Feng-Quan +1 more
A large inflationary tensor-to-scalar ratio r0.002 =0.20-0.05+0.07 is reported by the BICEP2 team based on their B-mode polarization detection, which is outside of the 95% confidence level of the Planck best fit model. We explore several possible ways to reduce the tension between the two by considering a model in …
Testing Dvali-Gabadadze-Porrati gravity with Planck
Xia, Jun-Qing; Li, Hong
Recently, the Planck Collaboration has released the first cosmological papers providing the highest resolution, full sky, maps of the cosmic microwave background (CMB) temperature anisotropies. It is crucial to understand that whether the accelerating expansion of our universe at present is driven by an unknown energy component (Dark Energy) or a …
Light dark matter annihilations into two photons
Boehm, C.; Orloff, J.; Salati, P.
We compute the pair annihilation cross section of light (spin-0) dark matter particles into two photons and discuss the detectability of the monochromatic line associated with these annihilations.
Unstable relics as a source of galactic positrons
Pospelov, Maxim; Picciotto, Charles
We calculate the fluxes of 511 keV photons from the galactic bulge caused by positrons produced in the decays of relic particles with masses less than 100 MeV. In particular, we tighten the constraints on sterile neutrinos over a large domain of the mass-mixing angle parameter space, where the resulting photon flux would significantly exceed the e…
Cosmic protons
Usoskin, I.; Laitinen, T.; Valtonen, E. +200 more
The primary proton spectrum in the kinetic energy range 0.2 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at an altitude of 380 km. The complete data set combining three shuttle attitudes and including all known systematic effects is presented.
Leptons in near earth orbit
Usoskin, I.; Laitinen, T.; Valtonen, E. +199 more
The lepton spectra in the kinetic energy ranges 0.2 to 40 GeV for e- and 0.2 to 3 GeV for e+ were measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at altitudes near 380km. >From the origin of the leptons two distinct spectra were observed: a higher energy spectrum and a substantial secon…
Protons in near earth orbit
Finelli, F.; Santos, D.; Usoskin, I. +212 more
The proton spectrum in the kinetic energy range 0.1 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at an altitude of 380km. Above the geomagnetic cutoff the observed spectrum is parameterized by a power law. Below the geomagnetic cutoff a substantial second spectrum was observed concentrated at …
Helium in near Earth orbit
Usoskin, I.; Laitinen, T.; Valtonen, E. +201 more
The helium spectrum from 0.1 to /100 GeV/nucleon was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at altitudes near 380 km. Above the geomagnetic cutoff the spectrum is parameterized by a power law. Below the geomagnetic cutoff a second helium spectrum was observed. In the second helium spectra over the ener…
Search for antihelium in cosmic rays.
Finelli, F.; Santos, D.; Usoskin, I. +207 more
The alpha magnetic spectrometer (AMS) was flown on the space shuttle Discovery during flight STS-91 in a 51.7° orbit at altitudes between 320 and 390 km. A total of 2.86×106 helium nuclei were observed in the rigidity range 1 to 140 GV. No antihelium nuclei were detected at any rigidity. An upper limit on the flux ratio of antihelium to…
How uncertain are solar neutrino predictions?
Basu, Sarbani; Pinsonneault, M. H.; Bahcall, John N.
Solar neutrino fluxes and sound speeds are calculated using a systematic reevaluation of nuclear fusion rates. The largest uncertainties are identified and their effects on the solar neutrino fluxes are estimated.