LHC-friendly minimal freeze-in models Julia Harz in collaboration with G. Bélanger, N. Desai, A. Goudelis, A. Lessa, J.M. No, A. Pukhov, S. Sekmen, D. Sengupta, B. Zaldivar, J. Zurita based on JHEP 1902 (2019) 186, [arXiv:1811.05478]
The motivation WIMP miracle? • Minimal WIMP models are currently under tension due to no observations at the LHC, direct or indirect detection • Reason could be the realisation of (a) a complex WIMP model that can evade bounds e.g. higher DM mass, complex dark sector, coannihilation scenarios etc. (b) the freeze-in mechanism instead of freeze-out 2 Julia Harz LHC friendly minimal freeze-in models
Freeze-in versus Freeze-out Freeze-out DM = WIMP (1) Thermal equilibrium regime (T >> m) annihilation and production of DM in thermal equilibrium (2) Annihilation regime (T ~ m/10) SM particles not energetic enough to create DM particles (3) Freeze-out (T ~ m/30) Annihilation rate falls behind expansion rate →! DM abundance cooling down 3 Julia Harz LHC friendly minimal freeze-in models
Freeze-in versus Freeze-out Freeze-in DM = FIMP (1) DM not in thermal equilibrium with SM bath DM is feebly interacting with the SM bath; abundance negligible (2) DM production DM gets produced via decay of a heavier particle Y that is in equilibrium with the SM bath (3) Freeze-in when T falls below mass of parent particle Y, production gets Boltzmann suppressed cooling down 4 Julia Harz LHC friendly minimal freeze-in models
The model We consider an extension of the SM by a Z 2 -odd real scalar singlet s (DM) and a Z 2 -odd vector-like SU(2) singlet fermion F (parent) (1,1,-1) heavy lepton (3,1,-2/3) heavy up-type quark (3,1,1/3) heavy down-type quark Free parameters: two separate studies: heavy lepton & heavy up-type quark ● only 1 st and 2 nd generation ● 5 Julia Harz LHC friendly minimal freeze-in models
(In)direct constraints Heavy lepton Heavy quark • Electroweak precision data • Running of the strong coupling no mixing with SM fermions, SU(2) L singlets →! no relevant contributions Llorente, Nachman, 1807.00894 Ellis, Godbole, Gopalakrishna, Wells, 1404.4398 • • muon lifetime Meson mixing / K + → π + ss suppressed by small couplings y s f below current experimental limits • Lepton-Flavour-Violation • LHC searches for multi-jet plus missing energy subdominant • LEP OPAL, hep-ex/0507048 6 Julia Harz LHC friendly minimal freeze-in models
Cosmological constraints • Big-Bang Nucleosynthesis we consider 1cm < cτ < 10 4 m →! T~150 MeV →! heavy fermions decay well before onset of BBN • Lyman-α forest Boulebnane, Heeck, Nguyen, Teresi, 1709.07283 • Relic density relic density implies for a certain reheating temperature T R a specifjc DM mass m s 7 Julia Harz LHC friendly minimal freeze-in models
Link to Baryogenesis sphalerons Baryon asymmetry: Theoretically, we know the conditions on interactions that have to be fulfjlled →! 3 Sakharov conditions ● Baryon number violation Standard Model! ● C and CP violation New ● Out-of-equilibrium physics! zero temperature: instantons are suppressed above EWPT: sphalerons unsuppressed For many leptogenesis & baryogenesis models, sphalerons have to be effjcient. Hence, the reheating temperature T R has to be above T c [or to be precise above T*(Γ Sph /H < 1)]. 8 Julia Harz LHC friendly minimal freeze-in models
Collider constraints Long-lived particles (LLPs) • Large mass hierarchies / ofg-shell mediator • Compressed spectra • Small couplings / small rates 9 Julia Harz LHC friendly minimal freeze-in models
1 Heavy Stable Charged Particles (HSCP) • charged particle F is suffjciently long lived such that it decays outside of the detector →! ionizing tracks or “R-hadrons” • as heavier than SM particles • →! higher ionization energy loss / larger time-of-fmight (TOF) than SM particles • decay outside the tracker →! tracker-only analysis • decay outside the muon chamber →! tracker + TOF analysis (cτ > 10m) • comparison with upper limits obtained by production of staus (leptonic model) or stops (hadronic model) in a gauge mediated SUSY breaking model 8 TeV CMS analysis 18.8 fb -1 13 TeV CMS analysis 12.9 fb -1 CMS Coll., Searches for long-lived charged particles in pp collisions at √s=7 and 8 TeV, JHEP 07 (2013) 122, [arXiv:1305.0491] CMS Coll., Search for heavy stable charged particles with 12.9 fb−1 of 2016 data, CMS-PAS-EXO-16-036 (2016). 10 Julia Harz LHC friendly minimal freeze-in models
1 Heavy Stable Charged Particles (HSCP) CMS Coll., Searches for long-lived charged particles in pp collisions at √s=7 and 8 TeV, JHEP 07 (2013) 122, [arXiv:1305.0491] CMS Coll., Search for heavy stable charged particles with 12.9 fb−1 of 2016 data, CMS-PAS-EXO-16-036 (2016). 11 Julia Harz LHC friendly minimal freeze-in models
1 Heavy Stable Charged Particles (HSCP) • charged particle F is suffjciently long lived such that it decays outside of the detector →! ionizing tracks or “R-hadrons” • as heavier than SM particles • →! higher ionization energy loss / larger time-of-fmight (TOF) than SM particles • decay outside the tracker →! tracker-only analysis • decay outside the muon chamber →! tracker + TOF analysis (cτ > 10m) • comparison with upper limits obtained by production of staus (leptonic model) or stops (hadronic model) • F has smallish life time →! re-scale the effjciency of particles that surpasses the tracker (L = 3m) / detector (L = 11 m) • production cross section computed by using MADGRAPH_aMC@NLO CMS Coll., Searches for long-lived charged particles in pp collisions at √s=7 and 8 TeV, JHEP 07 (2013) 122, [arXiv:1305.0491] CMS Coll., Search for heavy stable charged particles with 12.9 fb−1 of 2016 data, CMS-PAS-EXO-16-036 (2016). 12 Julia Harz LHC friendly minimal freeze-in models
1 Heavy Stable Charged Particles (HSCP) Leptonic model: • 13 TeV data most constraining for large cτ, in particular with TOF • 8 TeV data more constraining for smaller cτ, due to more integrated luminosity 13 Julia Harz LHC friendly minimal freeze-in models
1 Heavy Stable Charged Particles (HSCP) Hadronic model: • heavy hadrons (R-hadrons) can fmip their charge when traversing the detector • tracker-only selection may fail tracker+TOF selection 14 Julia Harz LHC friendly minimal freeze-in models
2 Disappearing Tracks (DT) • isolated track reconstructed in the pixel and strip detectors without any hit in the outer tracker (CMS) or a track with only pixel hits (ATLAS) • ATLAS can reconstruct tracks down to 12 cm (new innermost tracking layer “IBL”); CMS 25-30 cm • CMS has better coverage for longer life times cτ > 1m • AMSB motivated scenario with mass degenerate lightest chargino and neutralino 13 TeV ATLAS analysis 36.1 fb -1 13 TeV CMS analysis 138.4 fb -1 ATLAS Coll., Search for long-lived charginos based on a disappearing-track signature in pp collisions at √s= 13TeV with the ATLAS detector, JHEP06(2018) 022, [arXiv:1712.02118] CMS Coll., Search for disappearing tracks as a signature of new long-lived particles in proton-proton collisions at √s=13 TeV, arXiv:1804.07321 15 Julia Harz LHC friendly minimal freeze-in models
2 Disappearing Tracks (DT) ATLAS Coll., Search for long-lived charginos based on a disappearing-track signature in pp collisions at √s= 13TeV with the ATLAS detector, JHEP06(2018) 022, [arXiv:1712.02118] CMS Coll., Search for disappearing tracks as a signature of new long-lived particles in proton-proton collisions at √s=13 TeV, arXiv:1804.07321 16 Julia Harz LHC friendly minimal freeze-in models
2 Disappearing Tracks (DT) • isolated track reconstructed in the pixel and strip detectors without any hit in the outer tracker (CMS) or a track with only pixel hits (ATLAS) • ATLAS can reconstruct tracks down to 12 cm (new innermost tracking layer “IBL”); CMS 25-30 cm • CMS has better coverage for longer life times cτ > 1m • AMSB motivated scenario with mass degenerate lightest chargino and neutralino • Recasting of two analyses of ATLAS and CMS 13 TeV ATLAS analysis 36.1 fb -1 13 TeV CMS analysis 138.4 fb -1 ATLAS Coll., Search for long-lived charginos based on a disappearing-track signature in pp collisions at √s= 13TeV with the ATLAS detector, JHEP06(2018) 022, [arXiv:1712.02118] CMS Coll., Search for disappearing tracks as a signature of new long-lived particles in proton-proton collisions at √s=13 TeV, arXiv:1804.07321 17 Julia Harz LHC friendly minimal freeze-in models
2 Disappearing Tracks (DT) 18 Julia Harz LHC friendly minimal freeze-in models
3 Displaced leptons (DL) / Vertices (DV) + MET • F can decay into both muon and electron • CMS search for non-prompt RPV violating SUSY decays into e/μ fjnal state • search optimized for lifetimes longer than prompt searches, but shorter than long- lived BSM signatures 8 TeV CMS analysis 19.7 fb -1 13 TeV CMS analysis 2.6 fb -1 CMS Coll., Search for Displaced Supersymmetry in events with an electron and a muon with large impact parameters, Phys. Rev. 1240 Lett. 114 (2015), no. 6 061801, [arXiv:1409.4789] CMS Coll., Search for displaced leptons in the e-mu channel, CMS-PAS-EXO-16-022 (2016). 19 Julia Harz LHC friendly minimal freeze-in models
3 Displaced leptons (DL) / Vertices (DV) + MET 20 Julia Harz LHC friendly minimal freeze-in models
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