Compressed SUSY search at the 13 TeV LHC using kinematic correlations and structure of ISR jets

Abstract

Abstract:The LHC search for nearly degenerate gluinos and neutralinos, which can occur, for example, in SUSY axion models, is limited by the reduced missing transverse momentum and effective mass in the events. We propose the use of kinematic correlations between jets coming from initial state radiation (ISR) in gluino pair production events at the 13 TeV LHC. A significant improvement in the signal to background ratio is obtained for the highly compressed gluino-neutralino search, by using cuts on the rapidity and azimuthal angle separation between the pair of tagged jets with the highest transverse momenta. Furthermore, the distribution of the azimuthal angle difference between the tagged jets in thegg+jets process is found to be distinctly different from the dominant background process of Z+jets. We also find quark and gluon jet tagging methods to be useful in separating the signal, which contains a higher fraction of gluon initiated jets compared to the dominant backgrounds.

Gluino mass limits with sbottom NLSP in coannihilation scenarios

“…Consequently to achieve the required σ eff , the mass difference of these strongly interacting sparticles with the LSP need to be larger compared to their electroweak counterparts in a co-annihilation scenario. As we will see, while the required mass difference is about 5-15 GeV for electroweak sparticles (see, e.g., [72,73]), for (third generation) squarks it is about [25][26][27][28][29][30][31][32][33][34][35] GeV. This has nontrivial consequences for the observability of b 1 coannihilation scenario at the LHC (to be discussed in the next section).…”

Study of dark matter and QCD-charged mediators in the quasidegenerate regime

“…As more interest has been focused on models with squeezed spectra, new strategies for probing such models at the LHC have been developed, including the use of spectator jets to give a transverse boost to the jets and missing transverse momentum. Some recent work has focused on the use of new kinematic variables [59], and on searches for displaced vertices [60]. It would be interesting to see if further refinements of these strategies could be used to probe this region of parameter space in which χ is a good thermal dark matter candidate.…”

Search for a compressed supersymmetric spectrum with a light gravitino

“…With the LHC already operating close to its near maximum centre-of-mass energy, consistent improvements in luminosity is expected to help accumulate enough data which will help probe the coloured sector mass to almost 3 TeV with some improvements for the weakly interacting sector too. This lack of evidence for any low scale SUSY events prompted the idea of a compressed sparticle spectrum [9][10][11][12][13][14][15][16][17][18][19][20][21], where the lightest SUSY particle (LSP) and the heavier sparticle states may be nearly degenerate. In such realizations of the mass spectra, the resulting final state jets and leptons from the decay cascades of the parent particles are expected to be very soft, including the overall missing transverse energy which is a manifestation of the available visible transverse momenta.…”