Split Supersymmetry at Colliders

TL;DR

Split supersymmetry decouples scalars while keeping gauginos and Higgsinos light, yielding a distinctive LHC signature of long-lived gluinos forming $R$-hadrons and direct electroweakino production, complemented by a linear collider program to probe RG-induced Yukawa structure. The study analyzes RG running from the high-scale $\tilde{m}$ to the weak scale, predicting a heavy gluino and four anomalous Yukawa couplings $\kappa_i$ that modify neutralino/chargino mixing; it also estimates LHC discovery reach for both charged and neutral $R$-hadrons and demonstrates that a future $e^+e^-$ collider can extract MSSM parameters plus $\kappa$ with percent-level precision. The work shows that measuring these Yukawa deviations would test the SpS framework and reveal information about the decoupled scalar sector, offering a clear path to distinguish SpS from traditional MSSM scenarios. Overall, the paper highlights the complementary roles of LHC and a linear collider in establishing the split-SUSY picture and accessing the heavy-scale physics indirectly through precision measurements of weak-scale states.

Abstract

We consider the collider phenomenology of split-supersymmetry models. We show that despite the challenging nature of the signals in these models the long-lived gluino can be discovered with masses in excess of 2 TeV at the LHC. At a future linear collider we will be able to observe the renormalization group effects from split supersymmetry, using measurements of the neutralino and chargino masses and cross sections.

Figures (10)

• Figure 1: Renormalization group flow of the gauge couplings (left), the gaugino--Higgsino mass parameters (centre), and the anomalous gaugino--Higgsino mixing parameters defined in eq.(\ref{['eq:sps1_kappa']}) (right). All curves are based on our reference point eq.(\ref{['eq:sps1']}).
• Figure 2: Gluino lifetime Muhlleitner:2003vg as a function of the common scalar mass $\widetilde{m}$.
• Figure 3: Fraction of the kinetic energy remaining when the $R$-hadron enters the muon detector. The black lines are for the triple-pomeron form of the $R$-hadron nucleon cross section, the red lines are for the simple cut-off form Baer:1998pg. The interaction length $\lambda_{R}$ is varied between twice the central value (solid), the central value (dashed) and half this value (dot-dashed). The dotted line shows where the $R$-hadron no longer passes the $p_T$ cut for the charged $R$-hadron analysis.
• Figure 4: Effect of the modelling of the interaction with the detector on the reconstructed $R$-hadron mass for different gluino masses. We show curves for $\lambda_{R}/2$ with the pomeron cross section form (solid), $\lambda_{R}/2$ with the cut-off form (dashed), $\lambda_{R}$ with the pomeron form (dot-dashed) and $2\lambda_{R}$ with the pomeron form (dotted). The probability for producing the $R_g^0$ is set to zero. We simulate one million events, which is less than one year of high-luminosity running for the all the masses shown.
• Figure 5: Discovery reach (a) and mass resolution (b) for charged $R$-hadrons. We require the observation of ten charged $R$-hadrons for four different integrated luminosities. We show the mass resolution $\Delta M/M$ for $100{\rm \, fb}^{-1}$.