Search

Searches for dark matter production at particle colliders are complementary to direct-detection and indirect-detection experiments and especially powerful for small masses, mx < 100 GeV. An important collider dark matter signature is due to the production of a pair of these invisible particles with the initialstate radiation of a standard model particle. Currently, collider searches use individual and nearly orthogonal final states to search for initial-state jets, photons or massive gauge bosons. We combine these results across final states and across experiments to give the strongest current collider-based limits in the context of effective field theories and map these to limits on dark matter interactions with nuclei and to dark matter self-annhiliation. [ABSTRACT FROM AUTHOR]

We repurpose the recent ATLAS search for same-sign top quarks in data with 1.0 fb∼' in the context of a search for production of four top quarks. Using the null results ofthat search, we place limits on the four-top-quark production cross section of about 1 pb. These limits are larger than the expected standard model rate for four-top-quark production, but are already strong enough to place interesting constraints on models which enhance that rate. We interpret these results in the context of models in which the right-handed top quark is composite and find limits on the compositeness scale of about 700 GeV. [ABSTRACT FROM AUTHOR]

We describe an effective theory of interaction between pairs of dark matter particles (denotedχ) and pairs of W bosons. Such an interaction could accommodate χX WW processes, which are a major focus of indirect dark matter experiments, as well as pp → W* → Wχk processes, which would predict excesses at the LHC in the W + ET final-state. We reinterpret an ATLAS W + ET analysis in the hadronic mode and translate the bounds to the space of indirect detection signals. We also reinterpret the W + ET analysis in terms of Kaluza-Klein graviton emission through the processes W* → WG and Z* ZG in which G is invisible. Finally, the final state is interpreted in terms of a W' model where W' → WZ, with W decaying hadronically and Z decaying to neutrinos. [ABSTRACT FROM AUTHOR]

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 nonflavor-tagged jet from the observational point of view. The decay mode h→gg is chosen as the benchmark since it is the dominant channel in the Standard Model, but the bound obtained is also applicable to the light quarks (j=u, d, s). We estimate the achievable bounds on the decay branching fractions through the associated production Vh(V=W±,Z). Events of the Higgs boson decaying into heavy (tagged) or light (untagged) jets are correlatively analyzed. We find that with 3000  fb−1 data at the HL-LHC, we should expect approximately 1σ statistical significance on the SM Vh(gg) signal in this channel. This corresponds to a reachable upper bound BR(h→jj)≤4 BRSM(h→gg) at 95% confidence level. A consistency fit also leads to an upper bound BR(h→cc)<15 BRSM(h→cc) at 95% confidence level. The estimated bound may be further strengthened by adopting multiple variable analyses or adding other production channels. [ABSTRACT FROM AUTHOR]