The Explanation Of AMS-2’s Positron Ratio Excess Based On Dark Matter’s Decay/Annihilation

The discovery of dark matter is an important modern cosmologyresearch achievement，and the research on dark matter s physcialproperties is also an important issue of phiysics.It has been eightyyears since the first evidence of dark matter found by Fritz Zwickys who came from CIT in1933,and now there is a lot of evidence thatcan prove the exitence of darkmatter,sucn as: the spin curve of sprialgalaxy，gravitational lens,the formation of large-scale structure ofthe universe,the anisotropic power azimuth spectrum of cosmologicalmicrowave background,and so on.but we know next to nothing about itwhithout its gravational effect.Physicist came up with lots of modelto explain the darkmatter,but none of them have been confirmed byexperiment,so testing wether those models is self-consistent orresonable is still the main part of dark matter detection.Theoretical physicists have proposed many new physics beyond thestandard model theory, in which many candidates for dark matterparticles are given,those candidates will decay or annihilate throughthe weak interaction, producing observable cosmic ray particles suchas high-energy pair, high-energy gamma rays, protons and anti-protons.Recent astronomical observations such as ATIC, PAMELA,Fermi,have observed a phenomenon that the energy spectrum of electronand positron has a overtop in high energy,that is also appeared onAMS-2result with a higher accuracy.The process of the dark matterparticles decay/annihilation provide a very attract-ive explanationon this overtop in high energy.In this papper we firstly wiewed the process that dark matterparticles come into positron/electron through decay/annihilation andit s affect on the cosmic ray positron/electron energy spectrum as asource of positron/electron,then we discussed the methond of indirectdetection dark matter partciles through separating the possile darkmatter deacy/annihilate signals from cosmic ray observation data.Atleast we analysis the latest data of positron/electron energy spectrummeasured by AMS-2,trying to explain the abnormal positron ratio throughdark matter deacy/annihilate,and propose a limition on the dark mattermodel which we used to explain the data.The first part of the article is the introduction.In the secondchapter we summarized the foundation of modern cosmology,i.e. the bigbang cosmology and discussed the role of dark matter in the earlyuniverse evolution period.The third chapter is the status of darkmatter detection,including several observational evidence of darkmatter mainstream, the basic nature of dark matter, dark matter model description and the spatial distribution of dark matter, dark matterparticles of detecting the status and the latest progress of theexperiment.The fourth chapter is the main part of this article.In this partwe discussed the indirect detection of dark matter particles from theperspective of cosmic rays.We firstly outlined the basic knowledgeabout cosmic rays,the propagation equation of particle in the universeand GALPROP process for simulation cosmic ray transmission.And then weanalyzed the annihilate/decay of dark matter particles produced highenergy as a source of positive/negative cosmic rays,process the para-meter set by solving the propagation equation approximately.Finally weanalyzes the AMS-2(alpha magnetic spectrometer) electron-positronspectrum observation data recently released and the overtopping ofpositron ratio in high energy compared with the expection oftraditional astrophysics source.We then gave an explaination throughdark matter and fited the parameters related to the progress of darkmatter turns into positron/electron through dacay/annihilation.Atleast,we gave an reasonability Analyze.