Composite Higgs models with extended symmetries can feature mesonic dark matter candidates. In fundamental CHMs, the origin of dark parity can be explained in the UV theory. Combined with top partial compositeness, this leads to non-chiral Yukawa interaction connecting mesonic DM with one dark top partner and one SM top. We examine the DM phenomenology in SU(6)/SO(6) and SU(6)/Sp(6) CHMs with the presence of dark top partners. Phenomenological constraints require the mass of top partner in even parity to be of the multi-TeV order.

South Korea

Haiying Cai

France

Giacomo Cacciapaglia

Dark top partner

We revisit the impact of top partial compositeness on electroweak precision observables in the misaligned vacuum basis. We identify a new source for S in the singlet mixing case, and for S-T in the bi-doublet mixing, stemming from misalignment in the gauge couplings of the top partners. Hence, a positive shift in T can be obtained in both cases, as preferred by the recent CDF measurement of the W mass. These results, obtained for the minimal fundamental coset SU(4)/Sp(4), apply to any composite Higgs model with top partial compositeness.

Partial compositeness under precision scrutiny

In the warped space model, the inter-brane distance can be stabilized by the Goldberger-Wise mechanism. Of particular importance, the stabilization potential calls for a proper identification of the dynamical degree of freedom. In this paper, we provided a complete calculation of the effective Lagrangian till the quadratic order that is generic for the Randall-Sundrum model and its N-brane (N ≥ 4) extensions. By applying the variation principle to a specific perturbation field, we derived the equations of motion and orthogonal conditions for decoupling the graviton. This approach is demonstrated to be equivalent to the analysis using the linearized Einstein equation. Our derivation clarifies that in the N-brane set up, just one degree of freedom for the radion field is dynamical, with the other modes eliminated by the gauge fixings. Thus we can directly generalize the GW stabilization to the N-brane model in a way similar to the RS1 scenario.

Effective Lagrangian and stability analysis in warped space

The radion equilibrium in the Randall-Sundrum (RS) model is guaranteed by the backreaction of a bulk scalar field. In this paper we study an extended scenario, where an intermediate brane exists in addition to the two branes at the fixed points, due to the discontinuity of bulk cosmology constants in two spatial regions. We conducted a complete analysis of the linearized Einstein’s equations after applying the Goldberger-Wise mechanism. Our result elucidates that in the presence of nonfixed point branes under the rigid assumption, a unique radion field is conjectured as legitimate in the RS metric perturbation. The cosmological expansion in this setup is briefly discussed.

Radion dynamics in the multibrane Randall-Sundrum model

We detail our discovery of a chiral enhancement in the production cross sections of massive spin-2 gravitons, below the electroweak symmetry breaking scale, that makes them ideal dark matter candidates for the freeze-in mechanism. The result is independent of the physics at high scales and points toward masses in the keV–MeV range. The graviton is, therefore, a sub-MeV dark matter particle, as favored by the small scale galaxy structures. We apply the novel calculation to a Randall-Sundrum model with multiple branes, showing a significant parameter space where the first two massive gravitons saturate the dark matter relic density.

Seung J. Lee

Massive Gravitons as Feebly Interacting Dark Matter Candidates

Singlet scalar dark matter can naturally arise in composite Higgs models as an additional stable pseudo-Nambu-Goldstone boson. We study the properties of such a candidate in a model based on <math><mrow><mi>SU</mi><mo>(</mo><mn>6</mn><mo>)</mo><mo>/</mo><mi>SO</mi><mo>(</mo><mn>6</mn><mo>)</mo></mrow></math>, with the light quark masses generated by 4-fermion interactions. The presence of nonlinearities in the couplings allows us to saturate the relic density for masses <math><mrow><mn>400</mn><mo>&lt;</mo><msub><mrow><mi>m</mi></mrow><mrow><mi>DM</mi></mrow></msub><mo>&lt;</mo><mn>1000</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>, and survive the bound from direct detection and indirect detection. The viable parameter regions are in reach of the sensitivities of future upgrades, like XENONnT and LZ.

China

Singlet dark matter in the <math><mrow><mi>SU</mi><mo>(</mo><mn>6</mn><mo>)</mo><mo>/</mo><mi>SO</mi><mo>(</mo><mn>6</mn><mo>)</mo></mrow></math> composite Higgs model

We propose a two-loop induced radiative neutrino model with hidden gauged <math><mi>U</mi><mo>(</mo><mn>1</mn><mo>)</mo></math> symmetry, in which dark matter of Dirac fermions arises. The relic density gets a contribution from annihilation and semiannihilation due to a residual <math><msub><mi>Z</mi><mn>3</mn></msub></math> parity. After imposing the requirement of neutrino oscillation data and lepton flavor violation bounds, we find that semiannihilation plays a crucial role in order to satisfy the relic density constraint <math><mrow><mn>0.117</mn><mo>&lt;</mo><mi>Ω</mi><msup><mrow><mi>h</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>&lt;</mo><mn>0.123</mn></mrow></math>, by proceeding near either one of two deconstructive scalar resonances. Our numerical analysis demonstrates the allowed region for the DM-scalar coupling with the DM mass in (80, 400) GeV.

Radiative neutrino model with semiannihilating dark matter

We propose a realisation of inverse seesaw model controlled by hidden <math><mi>U</mi><mo>(</mo><mn>1</mn><mo>)</mo></math> gauge symmetry, and discuss the impact of a bosonic dark matter (DM) candidate by imposing a <math><msub><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msub></math> parity. We present the detail of scalar spectra and apply the Casas-Ibarra parametrisation to fit the neutrino oscillation data. For this model, the allowed region is extracted to explain the observed relic density and the muon <math><mi>g</mi><mo>−</mo><mn>2</mn></math> discrepancy, satisfying flavor constraints with DM involved. We interpret the DM annihilation into <math><mover><mrow><mi>f</mi></mrow><mrow><mo>¯</mo></mrow></mover><mi>f</mi></math> including all SM charged fermions and investigate the direct detection to place the bound on DM-Higgs coupling. Finally the LHC DM production is explored in light of charged lepton pair signature plus missing transverse energy.

Takaaki Nomura

Hiroshi Okada

A neutrino mass model with hidden (1) Gauge Symmetry

We consider a realisation of composite Higgs models in the context of SU(6)/SO(6) symmetry, which features a custodial bi-triplet, two Higgs doublets and dark matter candidates. This model can arise from an underlying gauge-fermion theory. The general vacuum structure is explored using the top partial compositeness to generate a special vacuum characterised by a single angle aligned with the first Higgs doublet. We present the CP and Dark Matter ℤ2 parity in two different pNGB bases and analyse the spectra in the absence of tadpoles and tachyons. For the phenomenology, we discuss the constraints from electroweak precision tests and from a potentially light CP-odd singlet (other than the Dark Matter) in the model.