Search results for "annihilation"
showing 10 items of 1016 documents
Limits to the muon flux from WIMP annihilation in the center of the Earth with the AMANDA detector
2002
A search for nearly vertical up-going muon-neutrinos from neutralino annihilations in the center of the Earth has been performed with the AMANDA-B10 neutrino detector. The data sample collected in 130.1 days of live-time in 1997, ~10^9 events, has been analyzed for this search. No excess over the expected atmospheric neutrino background is oberved. An upper limit at 90% confidence level on the annihilation rate of neutralinos in the center of the Earth is obtained as a function of the neutralino mass in the range 100 GeV-5000 GeV, as well as the corresponding muon flux limit.
Proton-antiproton annihilation into ηηπ-observation of a scalar resonance decaying into ηη
1992
Abstract The results of a measurement of pp annihilation at rest into ηηπ 0 are presented. Assuming a resonance dominated model for the annihilation process an isoscalar J PC =0 ++ resonance decaying into ηη is observed with a mass of 1560±25 MeV/ c 2 and a width of 245±50 MeV/ c 2 .
Baryon Electromagnetic Form Factors at BESIII
2017
Abstract The BESIII experiment is running on the double-ring symmetric collider, BEPCII, at center-of-mass energies between 2.0 and 4.6 GeV. The collected data can be analyzed to measure the baryon electromagnetic form factors in direct e + e − -annihilation and in initial state radiation processes. In this paper, results on e + e − → p p ‾ and preliminary results on e + e − → Λ Λ ‾ based on the data collected by BESIII in 2011 and 2012 are presented. Preliminary results on the proton electromagnetic form factors measurement are also reported based on the analysis of e + e − → p p ‾ γ with 7 data samples at center-of-mass energies between 3.773 and 4.6 GeV.
Conservative upper limits on WIMP annihilation cross section from Fermi-LAT γ rays
2012
The spectrum of an isotropic extragalactic {\gamma}-ray background (EGB) has been measured by the Fermi-LAT telescope at high latitudes. Two new models for the EGB are derived from the subraction of unresolved point sources and extragalactic diffuse processes, which could explain from 30% to 70% of the Fermi-LAT EGB. Within the hypothesis that the two residual EGBs are entirely due to the annihilation of dark matter (DM) particles in the Galactic halo, we obtain stringent upper limits on their annihilation cross section. Severe bounds on a possible Sommerfeld enhancement of the annihilation cross section are set as well. Finally, we consider models for DM annihilation depending on the inver…
Indirect Dark Matter Search with Antideuterons: Progress and Future Prospects for General Antiparticle Spectrometer (GAPS)
2007
We report on recent accelerator testing of a prototype general antiparticle spectrometer (GAPS). GAPS is a novel approach for indirect dark matter searches that exploits the antideuterons produced in neutralino-neutralino annihilations. Many supersymmetry models, as well as other models based on extra dimensions, predict a primary antideuteron flux from dark matter annihilation that is much greater than the secondary and tertiary background sources at low energies. The GAPS method involves capturing antiparticles in a target material into excited energy states. The X-rays that are emitted as the antiparticle cascades to lower energy states before the exotic atom decays serve as a fingerprin…
Study of the decayDs+→K+K−e+νe
2008
Using 214fb-1 of data recorded by the BABAR detector at the PEPII electron-positron collider, we study the decay Ds+→K+K-e+νe. Except for a small S-wave contribution, the events with K+K- masses in the range 1.01-1.03GeV/c2 correspond to mesons. For Ds+→ e+νe decays, we measure the relative normalization of the Lorentz invariant form factors at q2=0, rV=V(0)/A1(0)=1.849±0.060±0.095, r2=A2(0)/A1(0)=0.763±0. 071±0.065 and the pole mass of the axial-vector form factors mA=(2.28-0.18+0.23±0.18)GeV/c2. Within the same K+K- mass range, we also measure the relative branching fraction B(Ds+→K+K-e+νe)/B(Ds+→K+K- π+)=0.558±0.007±0.016, from which we obtain the total branching fraction B(Ds+→ e+νe)=(2…
Constraining Nonstandard Neutrino-Electron Interactions
2007
We present a detailed analysis on nonstandard neutrino interactions (NSI) with electrons including all muon and electron (anti)-neutrino data from existing accelerators and reactors, in conjunction with the ``neutrino counting'' data (e- e+ -> nu nu gamma) from the four LEP collaborations. First we perform a one-parameter-at-a-time analysis, showing how most constraints improve with respect to previous results reported in the literature. We also present more robust results where the NSI parameters are allowed to vary freely in the analysis. We show the importance of combining LEP data with the other experiments in removing degeneracies in the global analysis constraining flavor-conservin…
Measurement of the branching fraction for ψ(3770) → γχc0
2016
Kolcu, Onur Buğra (Arel Author) --- Makale 70 yazarlıdır.
Report of the working group on searches
1998
The `Searches' working group discussed a variety of topics relating to present and future measurements of searches at LEP2. The individual contributions are included separately.
Vector form factor of the pion from unitarity and analyticity: a model-independent approach
2001
7 páginas, 2 figuras, 3 tablas.-- PACS number(s): 13.35.Dx, 12.39.Fe, 13.40.Gp, 13.65.1i