Dark matter motivated collider signatures in left-right - PowerPoint PPT Presentation

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures Dark matter motivated collider signatures in left-right supersymmetry Harri Waltari University of Southampton & Rutherford Appleton Laboratory & NExT Institute University of Helsinki & Helsinki Institute of Physics Southampton 23/10/2018 H. Waltari Dark matter motivated collider signatures in left-right supersymmetry

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures This talk should answer the questions What is left-right symmetry? How do you build a left-right symmetric supersymmetric model? What are the possible dark matter candidates in left-right supersymmetry? How can you find them at the LHC? This talk is based on 1702.02112 (MF,BF,KH,SKR,HW) and 1810.03891 together with Arindam Chatterjee, Mariana Frank, Benjamin Fuks, Katri Huitu, Subhadeep Mondal and Santosh Kumar Rai. H. Waltari Dark matter motivated collider signatures in left-right supersymmetry

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures What is left-right symmetry? The basic idea of left-right (LR) symmetry is that parity is a symmetry of Nature, which is spontaneously broken in weak interactions The gauge group must be extended to include right-handed weak interactions The generalization of electric charge is Q = I 3 L + I 3 R + ( B − L ) / 2 The gauge group of left-right symmetric models is SU(3) c × SU(2) L × SU(2) R × U(1) B − L The gauge group of left-right symmetry can come e.g. from the breaking of SO(10) H. Waltari Dark matter motivated collider signatures in left-right supersymmetry

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures LR symmetric models have right-handed doublets The left-handed matter is in doublets of SU(2) L as usual Left-right symmetry then implies that right-handed matter should also be in doublets of SU(2) R The right-handed neutrinos must be included ⇒ Dirac masses for neutrinos can be introduced (normal type-I seesaw forbidden by gauge symmetry!) The usual R-parity violating couplings of the MSSM are forbidden due to the B − L symmetry H. Waltari Dark matter motivated collider signatures in left-right supersymmetry

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures There are lots of Higgses in LR models To generate masses for fermions you need a Higgs field that is in the (2,2) representation of SU(2) L × SU(2) R Using only one bidoublet doesn’t lead to the correct pattern of masses and CKM-mixings ⇒ another bidoublet If only bidoublets are around, m ( W L ) = m ( W R ) ⇒ Need for Higgs fields that are singlets under SU(2) L and not under SU(2) R We choose triplets ( ⇒ seesaw mass term for ν R ) of SU(2) R with B − L = 2 ⇒ anomaly cancellation requires a triplet with B − L = − 2 and LR symmetry the corresponding triplets of SU(2) L The addition of a singlet is also phenomenologically motivated (breaking of SU(2) R and breaking of SUSY are independent) Altogether nine CP-even, seven CP-odd, six singly charged and four doubly charged Higgses H. Waltari Dark matter motivated collider signatures in left-right supersymmetry

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures The desired vacuum structure would be a neutral one. . . √ ϕ + � ϕ 0 � � � v d / 2 0 1 1 Φ 1 = → ϕ − ′ 0 ϕ 0 0 1 1 ′ 0 ϕ + � � � 0 0 � ϕ √ 2 2 Φ 2 = → ϕ − ϕ 0 0 v u / 2 2 2 √ √ δ − � δ 0 � � � 1 R / 2 0 v 1 R / 2 √ 1 R ∆ 1 R = → δ −− − δ − 1 R / 2 0 0 1 R √ � δ + δ ++ � � � 2 R / 2 0 0 √ √ ∆ 2 R = 2 R → − δ + δ 0 v 2 R / 2 0 2 R / 2 2 R √ S → v S / 2 , � ∆ 1 L � = � ∆ 2 L � = 0 . Terms proportional to v i v ′ i lead to W L - W R mixing, which is known to be very small. H. Waltari Dark matter motivated collider signatures in left-right supersymmetry

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures . . . but it is often unstable The determinant of the doubly charged Higgs mass matrix is negative if the triplet has a VEV ⇒ not a problem for ∆ L (can be inert), but a definite problem for ∆ R There are several proposed solutions: Spontaneous R-parity violation (˜ ν R VEVs) [Kuchimanchi, Mohapatra, hep-ph/9306290] Nonrenormalizable operators [Mohapatra, Rasin, hep-ph/9511391, Aulakh et. al., hep-ph/9707256] Adding triplets with B − L = 0 [Aulakh et. al., hep-ph/9703434, hep-ph/9712551] Radiative corrections [Babu, Mohapatra, 0807.0481] We choose the last option in our work to have a viable dark matter candidate and to have the gauge sector within the reach of the LHC. H. Waltari Dark matter motivated collider signatures in left-right supersymmetry

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures Neutralinos and right-handed sneutrinos are viable dark matter candidates The viable classes of dark matter candidates are neutralinos and right-handed sneutrinos Left-handed sneutrinos are excluded like in the MSSM Of the various neutralino options we have considered gaugino and bidoublet higgsino dark matter Gaugino dark matter works only through resonant annihilation close to m h / 2, all other regions produce too much dark matter The bidoublet higgsinos (four neutralinos and two charginos) always nearly degenerate, so coannihilation effects need to be taken into account The higgsino case points towards m DM ≃ 700 GeV, a heavy and compressed spectrum, a nightmare for collider searches H. Waltari Dark matter motivated collider signatures in left-right supersymmetry

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures Right-handed sneutrinos annihilate via gauge interactions The RH sneutrinos are a part of a doublet so they have a coupling to the SM-like Higgs, which is essentially a gauge coupling The coupling is so strong that no resonant annihilation is needed This coupling gives the leading annihilation channel, if RH neutrinos are lighter than the sneutrino, also a t -channel neutralino exchange will contribute Without coannihilations the mass of the sneutrino is the only free parameter ⇒ relic density predicts the sneutrino mass H. Waltari Dark matter motivated collider signatures in left-right supersymmetry

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures The only viable solution is close to 250 GeV Relic density constraints give two solutions but the lighter one is excluded by direct detection experiments Also the heavier one is close to being excluded H. Waltari Dark matter motivated collider signatures in left-right supersymmetry

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures Coannihilations allow a wider range of sneutrino LSP masses Coannhilations with fermions increase the effective annihilation cross section ( ⇒ heavier LSP mass), while coannihilations with other scalars decrease it Sneutrino LSP masses up to 700 GeV possible with coannihilating χ 0 +2˜ χ ± ) higgsinos, above that neutralinos become the LSP (4˜ H. Waltari Dark matter motivated collider signatures in left-right supersymmetry

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures The W R has a large branching ratio to SUSY decay modes Production cross section for sneutrinos or neutralinos/charginos very low, also the Higgs branching ratio h → ˜ χ ˜ χ only 0 . 4% for the gaugino-like LSP Superpartners can be produced in the decays of W R or Z ′ of which the former is always lighter in LRSUSY Branching ratio to neutralino-chargino pairs (bidoublet higgsinos) ∼ 22%, slepton-sneutrino pairs a few percent Idea: Fix spectrum from the relic density constraint and look at W R decays to sleptons (no coannihilations) or neutralino-chargino pairs (coannihilations) For the simple setup we did a selection of cuts of our own, for the coannihilation case we recasted an existing LHC analysis (CMS-SUS-16-039, 1709.05406) H. Waltari Dark matter motivated collider signatures in left-right supersymmetry

Introduction to left-right symmetry Dark matter candidates in LRSUSY Collider signatures We have a set of benchmarks for various DM scenarios Benchmark LSP m(LSP) m(NLSP) m( W R ) BP1 ν τ ˜ 278 609 3510 BP3 ν τ ˜ 388 406 3370 ˜ H 0 BP5 690 712 3370 B – ˜ ˜ Gaugino W R mix 62 300 3510 BP1: sneutrino LSP without coannihilations, BP3: sneutrino LSP coannihilating with higgsinos, BP5: higgsinos coannihilating with each other, Gaugino: bino-wino mixture LSP without coannihilations; further benchmarks in the articles H. Waltari Dark matter motivated collider signatures in left-right supersymmetry