Induced top-Yukawa coupling and suppressed Higgs mass parameters

In the scenarios with heavy top squarks, mass parameters of the Higgs field must be fine-tuned due to a large logarithmic correction to the soft scalar mass. We consider a new possibility that the top-Yukawa coupling is small above TeV scale. The large top mass is induced from strong Yukawa interaction of the Higgs with another gauge sector, in which supersymmetry breaking parameters are given to be small. Then it is found that the logarithmic correction to the Higgs soft scalar mass is suppressed in spite of the strong coupling, and the fine-tuning is ameliorated. We propose an explicit model coupled to a superconformal gauge theory which realizes the above situation.

Figure 1

The RG flows obtained by solving Eqs. (11, 12) are shown. The arrows indicate the direction toward IR. The points A and B represent the fixed points (13, 14) respectively.

Figure 2

Running behavior of $A_{\lambda }$ as well as the couplings, ${\alpha }_{\mathrm{SC}}=g_{\mathrm{SC}}^2/8{\pi }^2$ and ${\alpha }_{\lambda }=|\lambda {|}^2/8{\pi }^2$, in the transition region between the fixed points (A) and (B) is shown. The renormalization scale $\mu$ is represented by $t={log}_{10}(\mu /{\Lambda }_{\mathrm{SC}}^{\prime })$. These lines are obtained by solving Eqs. (11, 12, 24).

Figure 3

Running behavior of soft scalar masses $m_H^2$, $m_{\Phi }^2$ and $m_{\overline{\varphi }}^2$ is shown. The renormalization scale $\mu$ is represented by $t={log}_{10}(\mu /{\Lambda }_{\mathrm{SC}}^{\prime })$. We set $m_{H_u}^2/A_{\lambda }^2=0.1$ at $t=0$ as an example. These lines are obtained by solving Eqs. (24, 25, 26, 27) coupled with Eqs. (11, 12).