Discriminating Electroweak-ino Parameter Ordering at the LHC and Its Impact on LFV Studies

Abstract

Current limit on the dark matter relic abundance may suggest that $|μ|$ should be smaller than prediction in the minimal supergravity scenario (mSUGRA) for moderate $m_0$ and $m_{1/2}$. The electroweak-ino parameter $M_1, M_2$ and $|μ|$ are then much closer to each other. This can be realized naturally in the non-universal Higgs mass model (NUHM). Since the heaviest neutralino ($\tildeχ^0_4$) and chargino ($\tildeχ^\pm_2$) have significant gaugino components, they may appear frequently in the left-handed squark decay and then be detectable at the LHC. In such a case, we showed that the hierarchy of $M_1, M_2$ and $|μ|$ can be determined. In the light slepton mass scenario with non-vanishing lepton-flavor violation (LFV) in the right-handed sector, NUHM with small $|μ|$ corresponds to region of parameter space where strong cancellation among leading contributions to $Br(μ\to eγ)$ can occur. We showed that determination of electroweak-ino hierarchy plays a crucial role in resolving cancellation point of $Br(μ\to eγ)$ and determination of LFV parameters. We also discussed test of the universality of the slepton masses at the LHC and the implications to SUSY flavor models.

34 pages, 16 figures