A dark force for baryons

TL;DR

This work proposes gauging baryon number, U(1)_B, as a framework to naturally stabilize both the proton and dark matter while linking their present-day abundances. In a SUSY context, the model realizes a unified genesis of visible baryons and a GeV-scale dark matter candidate X via Affleck-Dine baryogenesis, generating comparable primordial asymmetries in the dark and visible sectors through a nonanomalous U(1)_D symmetry and transfer operators. The dark matter communicates with the visible sector primarily through a light baryonic gauge boson Z_B, with the DM coupling either vectorial or axial, leading to distinct direct-detection and collider phenomenology. A comprehensive set of constraints from B-factories, LEP, Tevatron monojet searches, and direct detection experiments is analyzed, showing viable parameter regions—particularly for GeV-scale mediators and leptophobic interactions—that make the baryonic dark force a testable and distinctive new physics scenario.

Abstract

We suggest the existence of a fundamental connection between baryonic and dark matter. This is motivated by both the stability of these two types of matter as well as the observed similarity of their present-day densities. A unified genesis of baryonic and dark matter is natural in models in which the baryon number is promoted to a spontaneously broken local gauge symmetry. This is illustrated in a specific class of SUSY models using the Affleck-Dine mechanism. The dark matter candidate in these scenarios is charged under the baryon gauge symmetry and must have a mass around the GeV scale to give the correct present-day abundance. We discuss constraints from B-factories, LEP, mono-jet searches at the Tevatron, and dark matter direct detection experiments. A baryonic dark force is shown to be consistent with all data for mediators as light as the GeV scale.

Figures (5)

• Figure 1: Constraints on a dark matter candidate. Left: $m_X=1$ GeV and a purely vector coupling with $q_V=4/3$. Right:$m_X=10$ GeV and a purely axial coupling with $q_A=4/3$. The filled areas are excluded by $\Upsilon \rightarrow invisible$ (left) or $\Upsilon \rightarrow hadrons$ (right) and the CDF monojet search. Tevatron projections assuming $10$ fb$^{-1}$ of integrated luminosity are also shown (dashed). The solid red line indicates the values for $(m_B, g_B)$ required to get the right DM abundance for a symmetric DM species (WIMP cross section). Asymmetric DM species must lie above the red curve.
• Figure 2: The ratio (\ref{["note3f'"]}) (model I) and (\ref{["note2f'"]}) (model II) between the primordial asymmetries of ordinary baryons and DM for $N=1$ as a function of a comman mass $M_{q^\prime}/T^*$ for the $q^\prime$-sector fields.
• Figure 3: The white area represents the allowed region in the parameter space $(m_B,g_B)$. These areas are excluded by the experimental bounds on the invisible and hadronic (dashed) widths of the $\Upsilon(1S)$ meson and the hadronic width of the $Z^0$ boson. The bounds from the invisible $\Upsilon$ width have been plotted for $q_{V,A}^2=1$, while the bound from the hadronic $Z^{0}$ width is independent of $q_{V,A}$. The coupling is bounded by $g_B\lesssim0.5$ in the low mass regime $m_B<m_Z$. The region in the figure near $m_B \sim m_Z$ is not accurate since here the mixing between $Z_B$ and $Z$ is large, which is beyond the validity of our small mixing approximation.
• Figure 4: In the left panel we show the region in $(g_{B},m_{B})$ space that is excluded by the Tevatron for the process $p\bar{p} \rightarrow X\bar{X} + j$ for a purely vector coupling of the dark matter to the gauge boson. The right panel shows the same exclusion but for a purely axial coupling of the dark matter to the gauge boson. The excluded region is shown for three different DM masses $m_{X} = 1, 5,$ and $10$ GeV, and assuming that the DM charge is $q_{V,A}=1$. Once the gauge boson $Z_{B}$ can be produced on shell the mass of the DM is irrelevant, as can be seen by the merging of three lines for $m_B\gtrsim2m_X$. When the DM is produced off-shell the bounds are in general weakened. This weakening of the bounds is amplified as the DM mass increases.
• Figure 5: Excluded area from monojet + ME events at the Tevatron assuming that the decay $Z_B\rightarrow X\overline{X}$ is allowed. Here ${\cal BR}(Z_B\rightarrow X\overline{X})=1$ for simplicity. For ${\cal BR}<1$ the bound on $g_B$ gets weakened by a factor $1/\sqrt{{\cal BR}}$.