The minimal B-L model naturally realized at TeV scale

TL;DR

The paper proposes a minimal B-L extension of the SM with classical conformal invariance, where Coleman-Weinberg-type radiative breaking in the B-L sector generates a TeV-scale breaking scale that drives electroweak symmetry breaking via a Higgs-portal coupling. It derives mass relations among the Z', SM-singlet φ, and right-handed neutrinos, and analyzes naturalness and Planck-scale stability constraints to bound the parameter space. The resulting TeV-scale spectrum yields testable collider signatures, notably Z' resonances at the LHC and potential access to the seesaw sector through Z' decays, with φ providing complementary Higgs phenomenology. The work offers a concrete, experimentally testable realization of radiative symmetry breaking linked to neutrino mass generation, within a small, highly constrained parameter space.

Abstract

In a previous paper, we have proposed the minimal B-L extended standard model as a phenomenologically viable model that realizes the Coleman-Weinberg-type breaking of the electroweak symmetry. Assuming the classical conformal invariance and stability up to the Planck scale, we will show in this paper that the model naturally predicts TeV scale B-L breaking as well as a light standard-model singlet Higgs boson and light right-handed neutrinos around the same energy scale. We also study phenomenology and detectability of the model at the Large Hadron Collider (LHC) and the International Linear Collider (ILC).

Figures (8)

• Figure 1: The RG improved effective potential. Here, we have taken $\alpha_{B-L}(0)=0.01$ and $\alpha_N=0$ for simplicity.
• Figure 2: The SM singlet Higgs boson mass as a function of the Yukawa coupling. Here we have taken $\alpha_{B-L}(0)=0.01$ and accordingly, fixed $\alpha_\lambda(0)$ to satisfy the stationary condition in Eq. (\ref{['condition']}). For $\alpha_N(0) \simeq 9.8 \alpha_{B-L}(0)$, the potential minimum at $\phi=M$ changes into the maximum.
• Figure 3: One-loop diagram inducing the mixing term $(\Phi^\dagger \Phi)(H^\dagger H )$ through the right-handed neutrinos.
• Figure 4: Two-loop diagrams inducing the mixing term $(\Phi^\dagger \Phi)(H^\dagger H )$ through the top-quarks and the $B-L$ gauge bosons. The wavy lines represent the propagators of the $B-L$ gauge bosons.
• Figure 5: The allowed parameter region is drawn. The upper region of the almost straight line (in green) is rejected by a requirement that the $B-L$ gauge coupling does not diverge up to the Planck scale. The upper-right side of the solid line (in red) is disfavored by the naturalness condition of the electroweak scale. The left of the solid line (in blue) has been already excluded by the LEP experiment, $M \gtrsim 3$ TeV. The left of the dashed line can be explored in 5-$\sigma$ significance at the LHC with $\sqrt{s}$=14 TeV and an integrated luminosity 100 fb$^{-1}$. The left of the dotted line can be explored at the ILC with $\sqrt{s}$=1 TeV, assuming 1% accuracy.