Muon g-2, Dark Matter Detection and Accelerator Physics

Abstract

We examine the recently observed deviation of the muon g - 2 from the Standard Model prediction within the framework of gravity mediated SUGRA models with R parity invariance. Universal soft breaking (mSUGRA) models, and models with non-universal Higgs and third generation squark/slepton masses at M_G are considered. All relic density constraints from stau-neutralino co-annihilation and large \tanβNLO corrections for b \to sγdecay are included, and we consider two possibilities for the light Higgs: m_h > 114 GeV and m_h > 120 GeV. The combined m_h, b \to sγand a_μ bounds give rise to lower bounds on \tanβand m_{1/2}, while the lower bound on a_μ gives rise to an upper bounds on m_{1/2}. These bounds are sensitive to A_0, e.g. for m_h > 114 GeV, the 95% C.L. is \tanβ> 7(5) for A_0 = 0(-4m_{1/2}), and for m_h > 120 GeV, \tanβ> 15(10). The positive sign of the a_μ deviation implies μ> 0, eliminating the extreme cancellations in the dark matter neutralino-proton detection cross section so that almost all the SUSY parameter space should be accessible to future planned detectors. Most of the allowed parts of parameter space occur in the co-annihilation region where m_0 is strongly correlated with m_{1/2}. The lower bound on a_μ then greatly reduces the allowed parameter space. Thus using 90% C. L. bounds on a_μ we find for A_0 = 0 that \tanβ\geq 10 and for \tanβ\leq 40 that m_{1/2} = (290 - 550) GeV and m_0 = (70 - 300) GeV. Then the tri-lepton signal and other SUSY signals would be beyond the Tevatron Run II (except for the light Higgs), only the \tildeτ_1 and h and (and for part of the parameter space) the \tilde{e}_1 will be accessible to a 500 GeV NLC, while the LHC would be able to see the full SUSY mass spectrum.

Figures (6)

• Figure 1: Corridors in the $m_0 - m_{1/2}$ plane allowed by the relic density constraint for $\tan\beta = 40$, $m_h > 111$ GeV, $\mu > 0$ for $A_0 = 0, -2m_{1/2}, 4m_{1/2}$ from bottom to top. The curves terminate at low $m_{1/2}$ due to the $b \rightarrow s\gamma$ constraint except for the $A_0 =4m_{1/2}$ which terminates due to the $m_h$ constraint. The short lines through the allowed corridors represent the high $m_{1/2}$ termination due to the lower bound on $a_{\mu}$ of Eq. (1).
• Figure 2: $\sigma_{\tilde{\chi}_1^0-p}$ as a function of the neutralino mass $m_{\tilde{\chi}_1^0}$ for $\tan\beta = 40$, $\mu > 0$ for $A_0 = -2 m_{1/2}, 4 m_{1/2}, 0$ from bottom to top. The curves terminate at small $m_{\tilde{\chi}_1^0}$ due to the $b \rightarrow s\gamma$ constraint for $A_0 = 0$ and $- 2 m_{1/2}$ and due to the Higgs mass bound ($m_h > 111$ GeV) for $A_0 = 4 m_{1/2}$. The curves terminate at large $m_{\tilde{\chi}_1^0}$ due to the lower bound on $a_{\mu}$ of Eq. (1).
• Figure 3: $\sigma_{\tilde{\chi}_1^0-p}$ as a function of $m_{\tilde{\chi}_1^0}$ for $\tan\beta = 10$, $\mu > 0$, $m_h > 111$ GeV for $A_0 = 0$ (upper curve), $A_0 = -4 m_{1/2}$ (lower curve). The termination at low $m_{\tilde{\chi}_1^0}$ is due to the $m_h$ bound for $A_0 = 0$, and the $b \rightarrow s\gamma$ bound for $A_0 = -4 m_{1/2}$. The termination at high $m_{\tilde{\chi}_1^0}$ is due to the lower bound on $a_{\mu}$ of Eq. (1).
• Figure 4: $\sigma_{\tilde{\chi}_1^0-p}$ as a function of $m_{1/2}$ ($m_{\tilde{\chi}_1^0} \stackrel{\sim}{=} 0.4 m_{1/2}$) for $\tan\beta = 40$, $\mu >0$, $m_h > 111$ GeV, $A_0 = m_{1/2}$ for $\delta_2 = 1$. The lower curve is for the $\tilde{\tau}_1-\tilde{\chi}_1^0$ co-annihilation channel, and the dashed band is for the $Z$ s-channel annihilation allowed by non-universal soft breaking. The curves terminate at low $m_{1/2}$ due to the $b \rightarrow s\gamma$ constraint. The vertical lines show the termination at high $m_{1/2}$ due to the lower bound on $a_{\mu}$ of Eq. (1).
• Figure 5: $\sigma_{\tilde{\chi}_1^0-p}$ as a function of $m_{1/2}$ for $\tan\beta = 40$, $\mu >0$, $A_0 = m_{1/2}$ and $m_h > 111$ GeV. The lower curve is for the bottom of the $\tilde{\tau}_1-\tilde{\chi}_1^0$ co-annihilation corridor, and the upper curve is for the top of the $Z$ channel band. The termination at low $m_{1/2}$ is due to the $b \rightarrow s\gamma$ constraint, and the vertical lines are the upper bound on $m_{1/2}$ due to the lower bound of $a_{\mu}$ of Eq. (1).