Pseudo Nambu-Goldstone bosons (pNGBs) are naturally light spin-zero particles, which can be interesting dark matter (DM) candidates. We study the phenomenology of a pNGB theta associated with an approximate symmetry of the neutrino seesaw sector. A small coupling of theta to the Higgs boson is induced radiatively by the neutrino Yukawa couplings. By virtue of this Higgs portal interaction (i) the pNGB acquires a mass m_theta proportional to the electroweak scale, and (ii) the observed DM relic density can be generated by the freeze-in of theta-particles with mass m_theta ~ 3 MeV. Alternatively, the coupling of theta to heavy sterile neutrinos can account for the DM relic density, in the 1 keV-3 MeV window. The decays of theta into light fermions are suppressed by the seesaw scale, making such pNGB sufficiently stable to play the role of DM.
Pseudo-Nambu-Goldstone dark matter connected to Standard Model fermion through the Higgs portal has the property that its direct detection vanishes in the zero momentum transfer limit due to a cancellation mechanism. This feature helps the Pseudo-Nambu-Goldstone dark matter to escape the stringent constraints from direct detection experiments. In this paper we explore new constraints on parameter space of non-zero momentum transfer from the direct detection experiments, and also from the neutron star temperature via the dark matter reheating mechanism.
The Standard Model(SM) vacuum is unstable for the measured values of the top Yukawa coupling and Higgs mass. Here we study the issue of vacuum stability when neutrino masses are generated through spontaneous low-scale lepton number violation. In the simplest dynamical inverse seesaw, the SM Higgs has two siblings: a massive CP-even scalar plus a massless Nambu-Goldstone boson, called majoron. For TeV scale breaking of lepton number, Higgs bosons can have a sizeable decay into the invisible majorons. We examine the interplay and complementarity of vacuum stability and perturbativity restriction…
It has been found that a pseudo-Nambu-Goldstone boson dark matter suppresses the amplitude for elastic scattering with nuclei in non-relativistic limit, and thus can naturally evade the strong constraint of dark matter direct detection experiments. In this paper, we show that non-zero elastic scattering cross section can be induced if the mediator mass is as small as momentum transfer. The predicted recoil energy spectrum can differ from that for usual thermal dark matter. Together with the relevant constraints such as thermal relic abundance, indirect detection and Higgs decays, we investigat…
We present a unified theory of inflation, neutrino mass, baryogenesis and dark matter where global lepton number symmetry and its breaking play a crucial role. The basic idea is to use a lepton number carrying complex scalar field as the inflaton as well as the field that implements Affleck-Dine (AD) leptogenesis. Dark matter is the massive majoron which is a pseudo-Goldstone boson, resulting from the spontaneous breaking of lepton number symmetry supplemented by explicit lepton number violation needed to implement AD leptogenesis. The magnitude of the resulting $n_B/s$ in the model is related…
Gauging the global $B-L$ (Baryon number minus Lepton number) symmetry in the Standard Model (SM) is well-motivated since anomaly cancellations require the introduction of three right-handed neutrinos (RHNs) which play an essential role in naturally generating tiny SM neutrino masses through the seesaw mechanism. In the context of the $B-L$ extended SM, we propose a pseudo-Goldstone boson dark matter (DM) scenario in which the imaginary component of a complex $B-L$ Higgs field serves as the DM in the universe. The DM relic density is determined by the SM Higgs boson mediated process, but its el…
We propose an ultraviolet completion model for pseudo-Nambu-Goldstone dark matter with a hidden $\mathrm{U}(1)$ gauge symmetry. Compared to previous studies, this setup is simpler, introducing less interactions. Dark matter scattering off nucleons is highly suppressed by the ultraviolet scale and direct detection constraints can be easily evaded. The kinetic mixing between the hidden $\mathrm{U}(1)$ and the $\mathrm{U}(1)_\mathrm{Y}$ gauge fields would lead to dark matter decays. We find that the current bound on the dark matter lifetime implies that the ultraviolet scale should be higher than…
General flavor changing interactions for a Goldstone boson (GB) to fermions due to a spontaneous global $U(1)_G$ symmetry breaking are discussed. This GB may be the Axion, solving the strong QCD CP problem, if there is a QCD anomaly for the $U(1)_G$ charge assignments for quarks. Or it may be the Majoron in models from lepton number violation in producing seesaw Majorana neutrino masses if the symmetry breaking scale is much higher than the electroweak scale. It may also, in principle, play the roles of Axion and Majoron simultaneously as far as providing solution for the strong CP problem and…
Possibility of a Right-Handed (RH) neutrino being a Goldstone fermion of a spontaneously broken global $U(1)$ symmetry in a supersymmetric theory is considered. This fermion obtains mass from the supergravity effects leading to a RH neutrino at the electroweak scale with a mass similar to the gravitino mass. A prototype model realizing this scenario contains just three gauge singlet superfields needed for the type I seesaw mechanism. Masses of the other two neutrinos are determined by the $U(1)$ breaking scale which too can be around the electroweak scale. Light neutrinos obtain their masses i…
Pseudo-Goldstone Boson Effects in Top-Antitop Productions at High Energy Hadron Colliders and Testing Technicolor Models
我们在费米实验室Tevatron Run II和CERN LHC上研究了各种Technicolor（TC）模型中的顶夸克对产生过程p+p（anti-p）-->top+antitop。s通道中性赝戈德斯通玻色子（PGB）通过技术夸克和顶夸克的三角环与胶子耦合产生振幅。计算了具有s通道PGB贡献的不同TC模型的截面。结果表明，PGB效应可以在实验上得到检验，并且在LHC上可以区分不同的TC模型。因此，在LHC上的p+p-->top+antitop过程为TC模型提供了可行的检验。
