Searches for Dark Matter at the LHC IMPRS Young Scientist Workshop - PowerPoint PPT Presentation

Searches for Dark Matter at the LHC IMPRS Young Scientist Workshop at Ringberg Castle Makoto Teshima | Max-Planck-Institut für Physik, München

Dark Matter (DM) gravitational interaction) beyond the standard model Makoto Teshima (MPP) Dark Matter 1 / 14 ◮ Much evidence for the presence of DM ◮ Galaxy rotation curves, gravitational lensing etc. (But only ◮ 23% of the universe is DM ◮ Explaining DM is one of the main motivations for physics ◮ One candidate for DM is WIMP

Weakly Interacting Massive Particle (WIMP) candidate electrically neutral Dirac Fermion 1 GeV-10 TeV Makoto Teshima (MPP) Dark Matter 2 / 14 ◮ Most favourite DM ◮ Stable, non-baryonic, ◮ Mostly WIMP taken as ◮ Expected mass range:

Ways to search for Dark Matter Makoto Teshima (MPP) Dark Matter 3 / 14

Mono-X searches any signal T Makoto Teshima (MPP) Dark Matter 4 / 14 ◮ At colliders: WIMP pair production ◮ However, without additional particles, WIMPs do not create ◮ WIMP production in association with visible SM particle(s) X results in signatures with E miss ◮ Search for Mono-X with X = jet, γ , W, Z, H ◮ Mono-jet is the most powerful search for DM at LHC

Simulation of WIMP production Simplified model Dark Matter Makoto Teshima (MPP) a new massiv mediator SM particles, including interaction of DM with EFT 5 / 14 momentum transfer interaction (EFT): 4-point ✓ ✏ ✓ ✏ ◮ Used in LHC Run 2 ◮ Effective Field Theory ◮ Expanding the contact ◮ Used in LHC Run 1 ◮ Spin 1 and 0 mediator ◮ But EFT invalid at large ◮ 4 free parameters ✒ ✑ ( m χ , m med , g SM , g DM ) ✒ ✑

Simulation of WIMP production the SM, include a Dark Matter Makoto Teshima (MPP) mediator interaction of DM with define benchmark models Simplified model (arXiv:1507.00966) Forum 6 / 14 ✓ ✏ ◮ Used in LHC Run 2 ◮ Expanding the contact ◮ Spin 1 and 0 mediator ◮ 4 free parameters ( m χ , m med , g SM , g DM ) ✒ ✑ ◮ ATLAS-CMS Dark Matter

Mono-jet search at ATLAS Makoto Teshima (MPP) Dark Matter 7 / 14

Mono-jet search at ATLAS Z+jets, W+jets Dark Matter Makoto Teshima (MPP) validation regions factor and test in signal free study backgrounds 8 / 14 > 250 GeV T ◮ Signal region: ◮ At least 1 jet with p T > 250 GeV ◮ E miss ◮ Lepton veto ◮ And up to 3 jets with p T > 30 GeV arrowed ◮ Dominant backgrounds: ◮ Control regions are used to ◮ Determine normalization

Mono-jet exclusion limits DM Makoto Teshima (MPP) Dark Matter 9 / 14 Perturbativity limits: m 2 DM g 2 med ) < 1 ( π M 2 2 For g DM =1: m DM < � π 2 M med

Exclusion limits for all Mono/Di-jet searches Makoto Teshima (MPP) Dark Matter 10 / 14

Exclusion limits for all Mono/Di-jet searches Makoto Teshima (MPP) Dark Matter 11 / 14

Comparison to direct detection experiments m n m DM Makoto Teshima (MPP) Dark Matter 12 / 14 g 2 DM µ 2 n χ Axial-vector mediator: σ SD ∝ med , µ n χ = M 4 ( m n + m DM )

Comparison to direct detection experiments m n m DM Makoto Teshima (MPP) Dark Matter 13 / 14 g 2 DM µ 2 n χ Vector mediator: σ SI ∝ med , µ n χ = M 4 ( m n + m DM )

Summary searches Speaker: Rainer Röhrig Makoto Teshima (MPP) Dark Matter 14 / 14 ◮ Most favoured DM candidate: WIMP ◮ Searches for DM at colliders ◮ Example: ATLAS Mono-jet analysis ◮ LHC searches for DM are complementary to (in)direct DM ◮ Next talk: Dark Matter and the Higgs Boson at ATLAS

Backup Makoto Teshima (MPP) Dark Matter 15 / 14

Weakly Interacting Massive Particle (WIMP) below the expansion rate of Dark Matter Makoto Teshima (MPP) out) thermal equilibrium (freeze insufficient to maintain interactions become the Universe and the DM 16 / 14 through pair annihilation cooled present in large number ◮ In early universe WIMPs are ◮ They are in theremal equilibrium χχ ← → ff ◮ Universe expanded and ◮ Density are reduced ◮ Annihilation rate drops

DM models Makoto Teshima (MPP) Dark Matter 17 / 14 ◮ invisible DM search (Mono-X) ◮ DM Mediator search (DI-X) ◮ spin 1 and 0 mediator, 4 free parameters (m χ ,m med ,g SM ,g DM )

Fitting Strategy Mono-Jet interpretation interpretation Makoto Teshima (MPP) Dark Matter 18 / 14 ◮ Background only fit ◮ Fit applied using 10 MET bins for model dependent ◮ Fit applied using inclusive MET cuts for model-indipendent