Search for narrow and broad dijet resonances in proton-proton collisions at $\sqrt{s}=$ 13 TeV and constraints on dark matter mediators and other new particles (1806.00843v2)

Abstract: Searches for resonances decaying into pairs of jets are performed using proton-proton collision data collected at $\sqrt{s} =$ 13 TeV corresponding to an integrated luminosity of up to 36 fb$^{-1}$. A low-mass search, for resonances with masses between 0.6 and 1.6 TeV, is performed based on events with dijets reconstructed at the trigger level from calorimeter information. A high-mass search, for resonances with masses above 1.6 TeV, is performed using dijets reconstructed offline with a particle-flow algorithm. The dijet mass spectrum is well described by a smooth parameterization and no evidence for the production of new particles is observed. Upper limits at 95% confidence level are reported on the production cross section for narrow resonances with masses above 0.6 TeV. In the context of specific models, the limits exclude string resonances with masses below 7.7 TeV, scalar diquarks below 7.2 TeV, axigluons and colorons below 6.1 TeV, excited quarks below 6.0 TeV, color-octet scalars below 3.4 TeV, W' bosons below 3.3 TeV, Z' bosons below 2.7 TeV, Randall-Sundrum gravitons below 1.8 TeV and in the range 1.9 to 2.5 TeV, and dark matter mediators below 2.6 TeV. The limits on both vector and axial-vector mediators, in a simplified model of interactions between quarks and dark matter particles, are presented as functions of dark matter particle mass and coupling to quarks. Searches are also presented for broad resonances, including for the first time spin-1 resonances with intrinsic widths as large as 30% of the resonance mass. The broad resonance search improves and extends the exclusions of a dark matter mediator to larger values of its mass and coupling to quarks.

Search for Dijet Resonances and Constraints on Dark Matter Mediators in Proton-Proton Collisions

This paper presents a comprehensive analysis of dijet resonances in proton-proton collision data gathered at a center-of-mass energy of 13 TeV, utilizing a total integrated luminosity of up to 36 fb⁻¹. The investigation focuses on identifying both narrow and broad resonances and simultaneously imposing constraints on potential dark matter mediators, extending our understanding of particle physics beyond the Standard Model.

Experimental Approach

The CMS detector was employed to perform two distinct searches to explore different mass spectrums of resonances. A low-mass search (0.6 to 1.6 TeV) was conducted, utilizing calorimeter information for trigger-level dijet reconstruction. An additional high-mass search (above 1.6 TeV) leveraged offline reconstruction with a particle-flow algorithm. The dijet mass spectrum from both searches exhibited a smooth parameterization with no distinct evidence of new particle production.

Key Findings

• Narrow Resonance Limits: The paper reports upper limits at the 95% confidence level on the cross sections for narrow resonances with masses above 0.6 TeV. These limits are highly informative in the context of various specific models, including string resonances, scalar diquarks, axigluons, colorons, excited quarks, etc.
• Mass Exclusions: Mass exclusions are substantial with string resonances excluded below 7.7 TeV, scalar diquarks below 7.2 TeV, axigluons and colorons below 6.1 TeV, excited quarks below 6.0 TeV, among others. These constraints significantly advance previous studies, enhancing the robustness of high-mass exclusions.
• Broad Resonance Search: For broader resonances, especially spin-1 resonances exhibiting widths up to 30% of the resonance mass, the paper provides new limits. This aspect markedly extends the constraints on dark matter mediators, accommodating a wider range of mass and coupling scenarios.

Theoretical and Practical Implications

The implications of this paper are profound, providing stringent tests of various theoretical models extending beyond the Standard Model. By not observing expected resonances across the scanned mass spectrums, the research imposes stringent constraints on new physics theories, necessitating further refinement in model parameters or exploration of alternative hypotheses. Additionally, understanding the couplings and constraints on dark matter mediators aids in connecting collider-based results with astrophysical dark matter observations, offering a cohesive approach to unveil the properties of dark matter.

Future Directions

This research opens avenues for future efforts in several ways:

1. Extended Searches: Continued analysis with higher integrated luminosity could refine current limits or perhaps reveal elusive resonances amidst refined experimental sensitivity.
2. Enhanced Modeling: Exploration of more complex or alternative theoretical models which might explain the observed spectra in light of undetected new particles.
3. Interdisciplinary Approaches: This could benefit observational strategies in astrophysics and cosmology aiming to uncover or constrain properties of dark matter paralleling collider findings.

In summary, the presented paper enriches the understanding of dijet resonances and dark matter mediator constraints within the high-energy physics community, providing a vital framework for both experimental and theoretical advancements in the field.