Cao, JJ (reprint author), Xi An Jiao Tong Univ, Dept Appl Phys, Xian 710049, Shanxi, Peoples R China.
We explore the explanation of the Fermi Galactic Center excess (GCE) in the next-to-minimal supersymmetric Standard Model. We systematically consider various experimental constraints including the dark matter (DM) relic density, DM direct detection results, and indirect searches from dwarf galaxies. We find that, for DM with mass ranging from 30 to 40 GeV, the GCE can be explained by the annihilation chi chi -> a* -> b (b) over bar only when the CP-odd scalar satisfies m(a) similar or equal to 2m(chi), and in order to obtain the measured DM relic density, a sizable Z-mediated contribution to DM annihilation must intervene in the early universe. As a result, the Higgsino mass mu is upper bounded by about 350 GeV. Detailed Monte Carlo simulations on the 3l + E-T(miss) signal from neutralino/chargino associated production at 14-TeV LHC indicate that the explanation can be mostly (completely) excluded at 95% C.L. with an integrated luminosity of 100(200) fb(-1). We also discuss the implication of possible large Z coupling to DM for the DM-nucleon spin dependent (SD) scattering cross section, and find that although the current experimental bounds on sigma(SD)(p) p is less stringent than the spin independent results, the future XENON-1T and LZ data may be capable of testing most parts of the GCE-favored parameter region.
ARC Center of Excellence for Particle Physics at the Tera-scale
; National Natural Science Foundation of China (NNSFC) [10821504, 11222548, 11305049, 11135003]
; Program for New Century Excellent Talents in University