SIGNALS FOR MINIMAL SUPERGRAVITY AT THE CERN LARGE HADRON COLLIDER: MULTI-JET PLUS MISSING ENERGY CHANNEL,

TL;DR

The paper analyzes the observability of missing transverse energy plus multi-jet signatures from SUSY particle production at the LHC within the minimal supergravity (SUGRA) framework with gauge coupling unification and radiative electroweak symmetry breaking. Using ISAJET/ISASUGRA, it simulates sparticle spectra, decays, detector effects, and SM backgrounds, deriving 5σ reach contours in the $m_0$–$m_{1/2}$ plane and showing gluino mass reach up to about 2 TeV for favorable squark–gluino mass patterns. It further demonstrates that jet multiplicity and hemispheric mass reconstruction can yield mass estimates and production-mode information, while Higgs bosons produced in cascade decays may be detectable in favorable parameter regions via $B$-tagging. Overall, the study argues that the LHC can perform a comprehensive scan of the minimal SUGRA parameter space and extract meaningful mass and decay information from the MET$+${ m multi-jet}$ channel, with complementary insights from slepton and chargino/neutralino searches.

Abstract

We use ISAJET to perform a detailed study of the missing transverse energy $\eslt$ plus multi-jet signal expected from superparticle production at the CERN LHC. Our analysis is performed within the framework of the minimal supergravity model with gauge coupling unification and radiative electroweak symmetry breaking. We delineate the region of parameter space where the $\eslt$ supersymmetry signal should be observable at the LHC and compare it to the regions explorable via searches for sleptons and for chargino/neutralino production. We confirm that, given a data sample of 10~$\fb^{-1}$, $m_{\tg}\sim 1300$ GeV can be explored if $m_{\tq}\gg m_{\tg}$, while $m_{\tg}\sim 2000$ GeV can be probed if $m_{\tq}\simeq m_{\tg}$. We further examine what information can be gleaned from scrutinizing this event sample. For instance, the multi-jet multiplicity yields information on whether squark production makes a significant contribution to the observed $\eslt$ sample. Furthermore, reconstructing hemispheric masses may yield a measure of $m_{\tg}$ to $\sim 15-25\%$. Finally, for favourable ranges of parameters, by reconstructing masses of tagged $b\bar{b}$ jet pairs, it may be possible to detect Higgs bosons produced via sparticle cascade decay chains.

Figures (12)

• Figure 1: Total cross section for strongly interacting sparticle pairs (solid), associated production of gluinos or squarks with charginos or neutralinos (dot-dashed) and chargino/neutralino production (dashes), for a) $m_{\tilde{q}}=m_{\tilde{g}}$ and b) $m_{\tilde{q}}=2m_{\tilde{g}}$, as a function of $m_{\tilde{g}}$, for $pp$ collisions at $\sqrt{s}=14$ TeV.
• Figure 2: Cross section in ${\rm fb}$ after cuts, as a function of cut parameter $E_T^c$, for total background ($\times$'s), and for the six signal cases listed in Table 1.
• Figure 3: a) Cross section in ${\rm fb}$ after cuts, as a function of $A_0/m_0$, for parameter choices shown. In b), we show variation in the cross section for Table 3 case 3 when $\tan\beta$ is varied.
• Figure 4: Background cross sections vs. $E_T^c$ obtained from various samples of events. The $p_T^{HS}$ range of the hard scattering subprocesses is listed.
• Figure 5: Signal cross sections for $m_0=m_{1/2}$ (squares) and $m_0=4m_{1/2}$ (triangles), after cuts, using $E_T^c=500$ GeV, as a function of $m_{\tilde{g}}$. We also show the $5\sigma$ background cross section assuming an integrated luminosity of $10$${\rm fb}^{-1}$. We take $A_0=0$, $\tan\beta =2$, and $\mu <0$.