Challenges for models with composite states

Composite states of electrically charged and QCD-colored hyperquarks (HQs) in a confining $\mathrm{SU}(N_{\mathrm{HC}})$ hypercolor gauge sector are a plausible extension of the standard model at the TeV scale and have been widely considered as an explanation for the tentative LHC diphoton excess. Additional new physics is required to avoid a stable charged hyperbaryon in such theories. We classify renormalizable models allowing the decay of this unwanted relic directly into standard model states, showing that they are significantly restricted if the new scalar states needed for UV completion are at the TeV scale. Alternatively, if hyperbaryon number is conserved, the charged relic can decay into a neutral hyperbaryon. Such theories are strongly constrained by direct detection, if the neutral constituent hyperquark carries color or weak isospin, and by LHC searches for leptoquarks if it is a color singlet. We show that the neutral hyperbaryon can have the observed relic abundance if the confinement scale and the hyperquark mass are above TeV scale, even in the absence of any hyperbaryon asymmetry.

Figure 1

(a) Contribution to $c\to u\gamma$ from the model Eq. (1). (b) Contribution to $\mu \to e\gamma$ in the HB-violating model of Eq. (11).

Figure 2

LUX Limit [42, 43] on fractional density of electroweakly interacting hyperbaryonic dark matter, rescaling predictions for Dirac neutralino scattering by $Z$ exchange from Ref. [41].

Figure 3

Predicted LHC production cross section at $\sqrt{s}=13\mathrm{TeV}$ for $\overline{\mathrm{\Psi }}\mathrm{\Psi }$ pairs that hadronize into leptoquarklike bound states $\tilde{\mathrm{\Phi }}=\overline{\mathrm{\Psi }}S$, and CMS upper limits for heavy stable particles of charge 1 and 2.

Figure 4

Inverse Bohr radius of the hyperbaryon bound state versus ${\mathrm{\Lambda }}_{\mathrm{HC}}$, for several values of the HQ mass $m_S=3000$, 300, 100, 10, 1 GeV and $N=2$, 3, 4 (smaller $N$ gives lower curve for a given mass). Vertical bars show where the perturbative treatment breaks down and extrapolation of low-$\mathrm{\Lambda }$ behavior is used, for a given $m_S$.

Figure 5

Estimated relic abundance of the lightest neutral hyperbaryon versus confinement scale ${\mathrm{\Lambda }}_{\mathrm{HC}}$, for neutral HQ masses $m_S=1$, 10, 100, 3000 GeV (from bottom to top), and $N_{\mathrm{HC}}=2$, 3, 4 (from bottom to top for each $m_S$).

Figure 6

(a,b) Diagrams that induce a magnetic dipole for the neutral hyperbaryon. $G$ denotes the hypergluon in (b).

Figure 7

Upper limit from direct detection on gyromagnetic ratio for magnetic dipolar dark matter, found by updating results of Ref. [54].

Figure 8

Contours of ${\log }_{10}|f|$ for the loop function $f$ from Eq. (b2) for the dipole moment of neutral hypequarks.