Dark Matter Detection,Models and Constraints Ashok Kumar Goyal University of Delhi, India

The observation of Dark Matter is through its large scale gravitational interactions. Non-gravitational manifestation has yet to be observed. The nature of DM particles is still unknown i.e.( spin, mass, interactions with SM, real/complex boson or Dirac/Majorana fermion ) .   One of the ways to unravel the nature of DM particles is to search for its NON-GRAVITATIONAL INTERACTIONS with SM particles.

COUPP Chicago Observatory : 4kg CF3I bubble chamber. Direct Detection Spin independent and Spin-dependent Cross-sections in non-relativistic regime (v ~10-3 c and momentum transfer ~ 10-100 MeV ) are important quantities in Direct Detection. Some of the detectors are : XENON 100 : 62 Kg target mass. Gran Sasso Nat. Lab. Italy. CDMS-GE : germanium and silicon detectors : Soudan Underground Lab. in Minnesota COUPP Chicago Observatory : 4kg CF3I bubble chamber. Present Sensitivity on DM-Nucleon scattering cross- section σSI > 10-45 – 10-44 cm2 at XENON 100, LUX σSD > 10-38 – 10-39 cm2 at PICASSO, COUPP, XENON

For the spin-dependent cross-section , the leading term arises from the axial-vector and pseudo- scalar couplings at the quark level, we define 𝑵 𝐪 𝛄 𝛍 𝛄 𝟓 𝐪 𝑵 = 𝑺 𝝁 𝑵 𝚫𝒒 𝑵   Where 𝑺 𝝁 𝑵 is the spin of the nucleon and 𝚫𝒒 𝑵 gives the spin contribution of quarks in the nucleon. 𝚫𝒖 𝒑 = 𝚫𝒅 𝒏 =𝟎.𝟕𝟕 ; 𝚫𝒅 𝒑 = 𝚫𝒖 𝒏 =−𝟎.𝟒𝟎 ; 𝚫𝒔 𝒑 = 𝚫𝒔 𝒏 =−𝟎.𝟏𝟐

LHC Searches Production of DM at LHC through 𝑝𝑝→𝜒𝜒 will give rise to large missing energy ∉ 𝑇 . Signal observation requires at least a hard jet or a photon in association with ∉ 𝑇 or a dijet with ∉ 𝑇 . Atlas and CMS have looked for ∉ 𝑇 signature in association with hadronic jets, 𝑊 ± , ϒ, Z, t/b quarks as well as Higgs bosons in the final state. CMS studies are done at 𝑺 =𝟖 𝑻𝒆𝑽 at the integrated luminosity of 197 fb-1 . DM quark interactions are parameterized in the EFT frame-work. EFT description is quite adequate as large mass of the heavy mediator is not within the kinematic reach of LHC.

𝚲 sets the scale of DM-quark contact interaction and as long as the momentum transfer satisfies 𝑸 𝟐 < 𝒈 𝝌 𝒈 𝒒 𝚲 𝟐 , EFT is valid. S, V and A 𝜒−𝑞 interactions are studied for Dirac DM. The results are then translated as limits on 𝒎 𝑫𝑴 −𝝈 𝑺𝑰/𝑺𝑫 plane. Simplified s-channel models with vector mediator and V and A interactions are also studied. The cuts employed are ∉ 𝑇 >𝟏𝟐𝟎 𝑮𝒆𝑽, 𝒑 𝑻 𝒋 > 𝟖𝟎 𝑮𝒆𝑽 𝒂𝒏𝒅 𝜼 𝒋 <𝟐.𝟔 V.Khachatryanet.al.Coll. EPJC 75 (2015) ATLAS studies of ∉ 𝑇 +𝛾 are done at 𝑺 =𝟏𝟑 𝑻𝒆𝑽 at the integrated luminosity of 36.1 fb-1 with the cuts ∉ 𝑻 >𝟏𝟐𝟎 𝑮𝒆𝑽, 𝒑 𝑻 𝒋 >𝟖𝟎 𝑮𝒆𝑽 𝒂𝒏𝒅 𝜼 𝒋 < 𝟐.𝟔, 𝜟𝝓 𝜸, ∉ 𝑻 >𝟎.𝟒 ATLAS Coll. arXiv ; 1704.03848

Dark Matter Models The Dark Matter model should be able to account for the observed Relic density measured with great precision by the Planck Collaboration ΩDM h2 = 0.1198∓𝟎.𝟎𝟎𝟏𝟐 ΩDM is the DM mass density in units of critical density and h = 0.7 is todays Hubble constant in units of 100km/s-Mpc. The critical density ρC = 10-26 Kg/m3 = 3h2/8πG The parameters of the model (masses and couplings in the model) required to give the observed Relic density should in turn not be in conflict with the observed data.

DATA Direct spin independent or spin dependent DM-nuclear elastic scattering observational data where σSI> 10-45 – 10-44 cm2at XENON 100, LUX σSD> 10-38 – 10-39 cm2 at PICASSO, COUPP, XENON are already ruled out. Indirect detection constraints from the DM annihilation to SM particles subsequently decaying into photons and direct annihilation into photon pairs giving rise to diffuse gamma ray flux in the former and to specific gamma ray spectral lines in the latter case. The thermally averaged annihilation cross-section greater than 10-25 cm3s-1 ruled out. LHC searches looking for a monojet or a dijet signal with associated missing energy provide stringent bounds on the model parameters.

SM and Dark Matter Even though not much about the nature, properties and interaction of the dark matter with the SM particles is known, it is enough to exclude all elementary particles described by the Standard model. Neutrinos are the only non-baryonic, massive neutral particles but are too light to account for the observed relic density. To obtain the requisite relic density neutrino mass should be of the order of about 16 eV. Baryonic content of the Universe comes from Big Bang Nucleo- synthesis (BBN) which implies that baryon density can not be more than 5% of critical density. We need to look for beyond the SM.

Thank You To be continued

Dark Matter Models Ashok Goyal University of Delhi

WIMP MODELS Weakly interacting massive particles (WIMPS) in the mass range lying between roughly 10GeV—2-3 TeV emerge as the most attractive proposal, giving the right relic density (WIMP MIRACLE). Two such models discussed in the literature are : Effective Field Theoretic (EFT) Models Simplified Models

Thank You Ashok Goyal