Search for new phenomena in dijet events using 37  fb−1 of pp collision data collected at

Abstract

Dijet events are studied in the proton-proton collision data set recorded at ffiffi ffi s p ¼ 13 TeV with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to integrated luminosities of 3.5 fb −1 and 33.5 fb −1 respectively. Invariant mass and angular distributions are compared to background predictions and no significant deviation is observed. For resonance searches, a new method for fitting the background component of the invariant mass distribution is employed. The data set is then used to set upper limits at a 95% confidence level on a range of new physics scenarios. Excited quarks with masses below 6.0 TeV are excluded, and limits are set on quantum black holes, heavy W 0 bosons, W Ã bosons, and a range of masses and couplings in a Z 0 dark matter mediator model. Model-independent limits on signals with a Gaussian shape are also set, using a new approach allowing factorization of physics and detector effects. From the angular distributions, a scale of new physics in contact interaction models is excluded for scenarios with either constructive or destructive interference. These results represent a substantial improvement over those obtained previously with lower integrated luminosity.

Measurements of tt¯ differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in pp collisions at Aaboud1, Aad2, Abbott3 et al. 2018Phys. Rev. DSelf Cite442340View full textAdd to dashboardCite

“…In summary, all of these results are in agreement with earlier differential cross-section measurements in the tt final states involving at least one lepton [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Those studies observed a "softer" p T spectrum for the top-quark final states, although the statistical and systematic FIG.…”

“…The signature of a tt final state is therefore determined by the W boson decay modes. The ATLAS [7][8][9][10][11][12][13][14] and CMS [15][16][17][18][19][20] [21]. The analysis presented here makes use of the allhadronic tt decay mode, where only top-quark candidates with high p T are selected.…”

Higgs bosons with large couplings to light quarks

“…We exclude events with a top in the final state (as in e.g. [84,91]), since top decays will generically not reconstruct into a single jet. We do include tops in the final state when calculating the Higgs widths and branching fractions.…”

Mixed gluinos and sgluons from a new SU(3) gauge group

“…) M X to each flavor of quark-antiquark pair, but can also in principle have loop-induced decays to gluon pairs. In particular, they can be produced singly as dijet resonances via qq → X → qq, resulting in the most recent LHC bound of M X > 6.6 TeV assuming g A = g B [80][81][82][83][84][85]. However, in the context of the present paper the bounds will be somewhat weaker if g A < g B , as in the example model of the previous section.…”