Jets + Missing Energy Signatures At The Large Hadron Collider

In this work we consider new ways to use jets plus missing energy signatures in searches at the Large Hadron Collider.

We study the Higgs boson (h) decay to two light jets at the 14 TeV High-Luminosity- LHC (HL-LHC), where a light jet (j) represents any non-flavor tagged jet from the obser- vational point of view. We estimate the achievable bounds on the decay product branching fractions through the associated production V h (V = W ± , Z). As a reasonable estimation, we only focus on the boosted region of high p T (h) and the three leptonic decay channels of the vector boson. We find that with 3000 fb −1 data at the HL-LHC, we should expect approximately 1σ statistical significance on the SM V h(gg) signal in this channel. This cor- responds to a reachable upper bound BR(h → jj) ≤ 4 BR SM (h → gg) at 95% confidence level. A consistency fit also leads to an upper bound of BR(h → cc) < 15 BR SM (h → cc) at 95% confidence level. The estimated bound may be further strengthened by adopting multiple variable analyses, or adding other production channels.

We then consider some simple machine learning techniques applied to the same channels. We use both a Fully Connected Neural Network (FCN) and a Convolutional Neural Network (CNN) on a statistically identical dataset as the one used for the cuts-based analysis of the Higgs decay to light jets. We found that that both networks improved upon the cuts-based results in two of the three signal channels, and roughly matched the cuts-based analysis on the third. This gave an improvement on the significance of the analysis from 0.59 for the cuts-based analysis to 0.61 using the FCN, and 0.62 using the CNN.<\p>

Finally we consider the HL-LHC discovery potential in the 3 ab −1 data set for gluinos in the gluino-weakino associated production channel. We propose a search in the jets plus missing energy channel which exploits kinematic edge features in the reconstructed transverse mass of the gluino. We find that for squark masses in the 2 TeV range we have 5 sigma discovery potential for gluino masses in the range of 2.4 to 3 TeV, competitive with the projections for discovery potential in the gluino pair production channel.