Displaced RPV SUSY & Baryogenesis Yanou Cui Perimeter Institute Long-lived BSM particles @ LHC workshop UMass-Amherst, Nov 12, 2015 1
Displaced SUSY • Gauge mediation: NLSP → gravitino + SM decay suppressed by 1/ F 2 , displaced with F ≳ 10 4 TeV • Anomaly mediation: co-LSP winos decay suppressed by mass degeneracy ∆ m ∼ m ᴨ ⇒ long disappearing track • Mini-split spectrum: NLSP → SM + LSP (RPC) decay suppressed by 1/(m 0 ) 4 + 3-body • R-parity violation: decay suppressed by tiny RPV couplings (UDD, LLE, QDL…) (or w/mini-split spectrum) 2
Displaced SUSY • Gauge mediation: NLSP → gravitino + SM decay suppressed by 1/ F 2 , displaced with F ≳ 10 4 TeV • Anomaly mediation: co-LSP winos decay suppressed by mass degeneracy ∆ m ∼ m ᴨ ⇒ long disappearing track • Mini-split spectrum: NLSP → SM + LSP (RPC) decay suppressed by 1/(m 0 ) 4 + 3-body • R-parity violation: decay suppressed by tiny RPV couplings (UDD, LLE, QDL…) (or w/mini-split spectrum) - Generically motivated by cosmology: baryogenesis! 2
Displaced SUSY • Gauge mediation: NLSP → gravitino + SM decay suppressed by 1/ F 2 , displaced with F ≳ 10 4 TeV • Anomaly mediation: co-LSP winos decay suppressed by mass degeneracy ∆ m ∼ m ᴨ ⇒ long disappearing track • Mini-split spectrum: NLSP → SM + LSP (RPC) decay suppressed by 1/(m 0 ) 4 + 3-body • R-parity violation: decay suppressed by tiny RPV couplings (UDD, LLE, QDL…) (or w/mini-split spectrum) - Generically motivated by cosmology: baryogenesis! (see Brock’s talk for more!) 2
Cosmological Concern with RPV Natural SUSY 3
Cosmological Concern with RPV Natural SUSY of ◆ • Light stop with RPV ( ) prompt decay: An important B natural channel of natural SUSY search at the LHC prompt ⇒ λ ij ≳ 10 -7 ( L decay ≳ 1 mm ) 3
Cosmological Concern with RPV Natural SUSY of ◆ • Light stop with RPV ( ) prompt decay: An important B natural channel of natural SUSY search at the LHC prompt ⇒ λ ij ≳ 10 -7 ( L decay ≳ 1 mm ) • Assume conventional baryogenesis at T ≳ T EW pre-existing baryon abundance efficiently erased by ∗ B ˜ H u t ! ¯ d i ¯ scatterings, e.g. ,, if λ ij ≳ 10 -7 ! of ◆ d j B natural 3
Cosmological Concern with RPV Natural SUSY of ◆ • Light stop with RPV ( ) prompt decay: An important B natural channel of natural SUSY search at the LHC prompt ⇒ λ ij ≳ 10 -7 ( L decay ≳ 1 mm ) • Assume conventional baryogenesis at T ≳ T EW pre-existing baryon abundance efficiently erased by ∗ B ˜ H u t ! ¯ d i ¯ scatterings, e.g. ,, if λ ij ≳ 10 -7 ! of ◆ d j B natural 3
Cosmological Concern with RPV Natural SUSY of ◆ • Light stop with RPV ( ) prompt decay: An important B natural channel of natural SUSY search at the LHC prompt ⇒ λ ij ≳ 10 -7 ( L decay ≳ 1 mm ) • Assume conventional baryogenesis at T ≳ T EW pre-existing baryon abundance efficiently erased by ∗ B ˜ H u t ! ¯ d i ¯ scatterings, e.g. ,, if λ ij ≳ 10 -7 ! of ◆ d j B natural ★ Estimate of washout: exponential reduction if Γ w ≳ H (T EW ) λ 2 ij y 2 M pl t R T ini Γ W ( T ) − dT g 1 / 2 m EW Y B ( 0 ) = Y ini B e − T ⇠ Y init B e 0 H ( T ) ∗ 3
Cosmological Concern with RPV Natural SUSY of ◆ • Light stop with RPV ( ) prompt decay: An important B natural channel of natural SUSY search at the LHC prompt ⇒ λ ij ≳ 10 -7 ( L decay ≳ 1 mm ) • Assume conventional baryogenesis at T ≳ T EW pre-existing baryon abundance efficiently erased by ∗ B ˜ H u t ! ¯ d i ¯ scatterings, e.g. ,, if λ ij ≳ 10 -7 ! of ◆ d j B natural ★ Estimate of washout: exponential reduction if Γ w ≳ H (T EW ) λ 2 ij y 2 M pl t R T ini Γ W ( T ) − dT g 1 / 2 m EW Y B ( 0 ) = Y ini B e − T ⇠ Y init B e 0 H ( T ) ∗ 3
Cosmological Concern with RPV Natural SUSY of ◆ • Light stop with RPV ( ) prompt decay: An important B natural channel of natural SUSY search at the LHC prompt ⇒ λ ij ≳ 10 -7 ( L decay ≳ 1 mm ) • Assume conventional baryogenesis at T ≳ T EW pre-existing baryon abundance efficiently erased by ∗ B ˜ H u t ! ¯ d i ¯ scatterings, e.g. ,, if λ ij ≳ 10 -7 ! of ◆ d j B natural ★ Estimate of washout: exponential reduction if Γ w ≳ H (T EW ) λ 2 ij y 2 M pl t R T ini Γ W ( T ) − dT g 1 / 2 m EW Y B ( 0 ) = Y ini B e − T ⇠ Y init B e 0 H ( T ) ∗ What are possible solutions to this problem? 3
Avoid the Problem: Suppress RPV Washout • To ensure successful baryogenesis at T ≳ T EW … (?) Natural SUSY with λ ij ≲ 10 -7 ⇒ Displaced Stop at LHC! (Barry, Graham and Rajendran 2013) ★ Good coverage up to m ∼ 1TeV w/recent development at ATLAS/CMS! (colored, low bkg) _ _ ~ _ _ t ! b b (DRPV) ~ t ! d s (RPV) charged stable charged stable charge-stripped charge-stripped L H C 8 p LHC8 projection r o j e c t i o n C M S ATLAS µ+tracks d i j e CMS dijet t ATLAS HCAL ATLAS HCAL ATLAS µ spect ATLAS µ spect prompt paired dijets prompt paired dijets jet substructure jet substructure (projection) (projection) Liu and Tweedie, 2015 4
Solve the Problem: Baryogenesis from RPV • Baryogenesis at T ≲ T EW , after all washout processes decouple ( Γ w ≲ H ) ? — RPV reset/regenerate Ω B !? (new ideas…) 5
Solve the Problem: Baryogenesis from RPV • Baryogenesis at T ≲ T EW , after all washout processes decouple ( Γ w ≲ H ) ? — RPV reset/regenerate Ω B !? (new ideas…) • Could SUSY shed light on prominent puzzles in modern cosmology? Ω DM ≈ 23% , Ω B ≈ 5% , Ω B ~ Ω DM MET - Familiar/well-studied case: (RPC) LSP χ DM p p WIMP dark matter, MET+X search @LHC χ DM ISR MET 5
Solve the Problem: Baryogenesis from RPV • Baryogenesis at T ≲ T EW , after all washout processes decouple ( Γ w ≲ H ) ? — RPV reset/regenerate Ω B !? (new ideas…) • Could SUSY shed light on prominent puzzles in modern cosmology? Ω DM ≈ 23% , Ω B ≈ 5% , Ω B ~ Ω DM MET - Familiar/well-studied case: (RPC) LSP χ DM p p WIMP dark matter, MET+X search @LHC χ DM ISR - Potential addressing Ω B, Ω B ~ Ω DM w/RPV? MET ⟹ (again) Displaced vertices @LHC! 5
Let’s start a journey beyond SUSY, then come back… 6
Let’s start a journey beyond SUSY, then come back… Mini-Review of Baryogenesis • Origin of Ω B ? = Where do we ourselves come from? symmetric component 10 B � ¯ Initial asymmetry B Asymmetric ⇡ annihilated away B ) /n γ ⇠ 10 � 10 η B = ( n B � n ¯ Ω B today 6
Let’s start a journey beyond SUSY, then come back… Mini-Review of Baryogenesis • Origin of Ω B ? = Where do we ourselves come from? symmetric component 10 B � ¯ Initial asymmetry B Asymmetric ⇡ annihilated away B ) /n γ ⇠ 10 � 10 η B = ( n B � n ¯ Ω B today Sakharov Conditions (1967): • Baryon number violation • C-, CP-violation (- provided by RPV SUSY ?…) B • Out-of equilibrium (CPT) n eq B = n eq B , h B i eq = 0 ¯ 6
Let’s start a journey beyond SUSY, then come back… Mini-Review of Baryogenesis • Origin of Ω B ? = Where do we ourselves come from? symmetric component 10 B � ¯ Initial asymmetry B Asymmetric ⇡ annihilated away B ) /n γ ⇠ 10 � 10 η B = ( n B � n ¯ Ω B today Sakharov Conditions (1967): • Baryon number violation Ω B ≈ 5%: • C-, CP-violation Need BSM Physics! (- provided by RPV SUSY ?…) B • Out-of equilibrium (CPT) n eq B = n eq B , h B i eq = 0 ¯ 6
Let’s start a journey beyond SUSY, then come back… Mini-Review of Baryogenesis • Origin of Ω B ? = Where do we ourselves come from? symmetric component 10 B � ¯ Initial asymmetry B Asymmetric ⇡ annihilated away B ) /n γ ⇠ 10 � 10 η B = ( n B � n ¯ Ω B today Sakharov Conditions (1967): • Baryon number violation Ω B ≈ 5%: • C-, CP-violation Need BSM Physics! (- provided by RPV SUSY ?…) B • Out-of equilibrium (CPT) n eq B = n eq B , h B i eq = 0 ¯ ❖ Existing baryogenesis mechanisms: (leptogenesis, EWBG…) Most involve high M or/and T, direct experimental test impossible (c.f. WIMP DM for Ω DM ) 6
Baryogenesis from Out-of-Equilibrium Decay A general class of baryogenesis models (e.g. leptogenesis) • Assume a massive neutral particle χ Baryon asymmetry can be produced in its decay (B-, CP-violating) • Γ ( χ ! f ) 6 = Γ ( χ ! ¯ f ) n f � n ¯ f 6 = 0 • Typically, the inverse processes efficiently erase the asymmetry • But, if χ is long-lived, and decays only after T f < M χ : f f Inverse decay: X χ ✔ χ Boltzmann suppressed f f e − M χ /T decay 13 , X Out-of-equilibrium decay Sakharov conditions 7
Baryogenesis from Out-of-Equilibrium Decay f f χ ✔ X χ f f 13 • Asymmetry is robustly preserved if ( H : Hubble expansion rate) Weak washout scenario Γ χ < H ( T = M χ ), An intriguing observation ( YC , Sundrum 2012; YC , Shuve, 2014) • If χ has mass at weak scale (the new energy frontier LHC < H ( T EW ) ∼ 10 − 13 GeV is exploring!), numerology gives c ⌧ − 1 χ • Converting to decay length: c τ χ & mm Displaced vertex regime @LHC! 8
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