The Study On Explaining Galactic Center Gamma-Ray Excess By NMSSM

So far,a large number of high-energy particle physics experiments have proved that the standard model is the most accurate theory in all the fields of science today.Especially the discovery of Higgs bosons on LHC in 2012 completed the last brick of Standard Model.However there are still many other problems for Standard Model,such as hierarchy problem,non-conservation of baryon number and neutrino mass problem,which implies that there must exist new physics beyond Standard Model.The existence of dark matter is guaranteed by various cosmological and astrophysical observations,such as Gravitational Lensing and Bullet Cluster,but the details in particle physics of dark matter are still unrevealed and widely discussed,which has provided a good portal in searching for new physics.i.e.BSM.The Galactic Center Excess?GCE?of y-ray,based on data from Large Area Telescope on board Fermi Gamma-ray Space Telescope?Fermi-LAT?,has been confirmed by several groups including Fermi-LAT themselves.Interpretations from different view of sights have been proposed subsequently for offering supplementary y-ray sources.Although pulsars could explain GCE,dark matter could either.Some relevant study indicates that the galactic center excess of y-ray presents a spherical morphology centered on the galactic center and a spectrum consistent with DM annihilation.The main goal of this work is to explain GCE by photon produced by annihilation final states of WIMPs in the Next-to Minimal Supersymmetry Standard Model?NMSSM?and demonstrate the fitting of current DM detection experiment combining with DM direct detection experiment.Weakly Interacting Massive Particle?WIMP?is very popular to be counted as a DM candidate since its weak-force-mediated nuclear recoils may be detected,which is the principle of DM direct detection.The experiment of DAMA and Xenon IT in Italy,LUX in South Dakota USA and PandaX in Jinping China,are all underground experiments in search for dark matter with liquid xenon as the main body of detector.The Xenon and PandaX give the most stringent limits on WIMP-nucleus scattering experiments for different aspects respectively.One of the most attractive WIMPs is the Lightest Supersymmetry Particle?LSP?,such as the lightest Supersyrmmetry?SUSY?neutralino.SUSY is one of the most compelling physical models among beyond standard model physics.It has a concise and exquisite form and could not only incorporate SM into its framework but also solve the intractable problems in SM,which is the reason why SUSY is highly praised by theoretical physicists and phenomenologists and has always been the hotspot and frontier of physical research.The supersymmetry is a symmetry between fermionic degrees of freedom and bosonic degrees of freedom.The simplest version of supersymmetric algebras?super algebra?is to expand two supersymmetric generators on the original Poincare algebra.The basis of irreducible representations of super algebra is corresponding to a chiral supermultiplet which contains an equal number of fermion and boson degrees of freedom.Among a plenty of new physics models in SUSY framework,the Minimal Supersymrmetric Standard Model?MSSM?,which is the simplest SUSY model,used to be a good choice.The R parity of each term in MSSM Lagrangian is conserved which guarantees that MSSM theory could provide enough long life of proton which can be measured by experiment.The supersymmetry is broken at current scale and the soft breaking part provides the mass term of superparticle.After electroweak symmetry breaking,gauginos and higgsinos mix into neutrolinos and charginos mass eigenstates;and the mixing of the third generation of sfermions is the strongest.However,after a series of experiments updated their striking achievements,MSSM was no longer a good BSM model.The LSP in NMSSM is one of the most attractive WIMP dark matter candidate.We take the lightest neuralino which is singlino-dominated as the dark matter candidate and perform a sophisticated scan to figure out whether this kind of neutralino is able to explain GCE.By analysing the samples that is not only satisfying many experimental restrictions but also fitting GCE well,we obtain three main conclusions.Firstly,a larger velocity weighted DM annihilation cross section<?v>0 would fit GCE better.Secondly,the singlino-dominated neutralino pair ?????? maILly annihilates to the bottom pair b??? through s-channeI with mediator of a CP-odd Higgs boson A₁.Thirdly,the NMSSM GCE-samples are almost completely excluded by the restrictions of nucleus-??? cross section which is provided by dark matter direct detection experiment.