Gravitational waves from walls bounded by strings in SO(10) model of pseudo-Goldstone dark matter.

We explore the gravitational wave spectrum generated by string-wall structures in an S O (10) (S p i n (10)) based scenario of pseudo-Goldstone boson dark matter (pGDM) particle. This dark matter candidate is a linear combination of the Standard Model (SM) singlets present in the 126 and 16 dimensional Higgs fields. The Higgs 126-plet vacuum expectation value (VEV) 〈 126 H 〉 leaves unbroken the Z 2 subgroup of Z 4 , the center of S O (10). Among other things, this yields topologically stable cosmic strings with a string tension μ ∼ 〈 126 H 〉 2. The subsequent (spontaneous) breaking of Z 2 at a significantly lower scale by the 16-plet VEV 〈 16 H 〉 leads to the appearance of domain walls bounded by the strings produced earlier. We display the gravitational wave spectrum for Gμ values varying between 10 − 15 and 10 − 9 (〈 126 H 〉 ∼ 10 11 - 1014 GeV), and 〈 16 H 〉 ∼ 0.1 - 102 TeV range (G denotes Newton's constant.) These predictions can be tested, as we show, by a variety of (proposed) experiments including LISA, ET, CE and others. [ABSTRACT FROM AUTHOR]