Strongly Interacting Dark Sectors at Fixed Target Experiments .. .. - PowerPoint PPT Presentation

.... .... .... .... .... .... .... .... .... .... .... .... .... .... . . with thanks to Takashi Maruyama 1704.xxxxx with Asher Berlin, Philip Schuster and Natalia Toro US Cosmic Visions, March 23, 2017 SLAC National Accelerator Laboratory, California Nikita Blinov Strongly Interacting Dark Sectors at Fixed Target Experiments .. .. ... . ... . ... . ... . .. . . .. .. .. .

. .. .. . .. . . .. . . .. . . .. . . . . . 2/18 Does it couple to the the SM? We know there is a Dark Sector . .. . .. . . . .. . . .. .. . . . . .. .. . . .. . . .. . . .. . . .. . . . . . .. .. . .. . . .. . . .. . . Dark Sectors SM DS SU (2) W SU (3) C ✓ ǫ =? U (1) Y

. .. .. . .. . . .. . . .. . . .. . . . . . 2/18 Does it couple to the the SM? We know there is a Dark Sector . .. . .. . . . .. . . .. .. . . . . .. .. . . .. . . .. . . .. . . .. . . . . . .. .. . .. . . .. . . .. . . Dark Sectors SM DS χ SU (2) W SU (3) C ǫ =? U (1) Y

. .. .. . .. . . .. . . .. . . .. . . . . . PC: Kyle Cranmer/Particle Fever Does it couple to the the SM? We know there is a Dark Sector . .. . .. . . . .. . . .. .. . . . . .. .. . . .. . . .. . . .. . . .. . . . . . .. .. . .. . . .. . . .. . . 2/18 Dark Sectors SM DS SU (2) W SU (3) C ǫ =? U (1) Y

. . . .. .. . .. . . .. . . .. . . .. . .. .. . . .. . . .. . . .. . . .. . . . . .. . . .. . . .. . . .. . . .. . . . . . .. . . .. . . .. . . .. 3/18 . .. . Dark Matter Depletion Large initial density n dm ∼ T 3 RH must be depleted Annihilation ( 2 → 0 ) DM X DM X X ∈ SM or X talks to SM, otherwise new light d.o.f.

. .. . .. .. . . .. . . .. . . .. . . . . . See Hochberg, Kuflik, Volansky and Wacker (2014) and talk by Maxim Perelstein! Kinetic equilibrium with SM required for viable cosmology Carlson, Machacek and Hall (1992) . .. . .. . . . .. . . .. .. . . . . . .. . . .. . . .. . . .. . . .. .. . .. . . .. .. . . 3/18 . . .. . . . . .. Dark Matter Depletion Large initial density n dm ∼ T 3 RH must be depleted Cannibalization ( 3 → 2 , n → n − k ) DM DM DM DM DM

. . .. . .. .. . . .. . . .. . . .. . .. . .. freezes out when The reaction . .. . . . . . .. . . .. . . . .. .. . . .. . . .. . . .. . . .. . . . . . . .. . . .. . . .. . .. . 4/18 . .. . Characteristic Scales DM DM DM DM DM n 2 dm ⟨ σ v 2 ⟩ = H Solving for m dm , we find for O (1) couplings m dm ∼ 0 . 1 GeV

. .. . . .. . .. .. . . .. . . .. . . . . . Hochberg, Kuflik, Volansky and Wacker (2014), Hochberg, Kuflik and Murayama (2015) Below confinement, this is a theory of mesons: Previous considerations realized in confining gauge theories. . .. . .. . . . .. . . .. .. . . . . . .. . .. .. . . .. . . .. . . .. . . .. . . .. .. . . 5/18 . . .. . . .. . . QCD-like Theories G = SU ( N c ) × SU ( N f ) × SU ( N f ) Pseudo-Nambu-Goldstones π and vector mesons V π 1 2 k 2 k − 1 V µ 2 . . . π 3 4 Stable π make up the dark matter

. .. .. . . .. . . . . .. .. . . .. . . .. .. .. Hochberg, Kuflik, Volansky and Wacker (2014), Hochberg, Kuflik and Murayama (2015) Kinetic equilibrium maintained by V Neutral vector mesons via candidate . . . . .. . . .. . . . . . . . .. . . . . . .. . . .. . . .. .. . .. .. . . .. .. . . 6/18 . . . . . . .. .. Kinetic Equilibrium K.E. requires interactions active at low T ⇒ U (1) D dark photon a natural L ⊃ − 1 2 ε F µν F ′ µν A ′ couples to EM charges with strength ε e e D π π U (1) D charges with strength e D A ′ A ′ SM SM εe

. . .. . . .. . . .. .. . .. . . .. . .. . .. Rates depend on Two processes determine abundance: . .. . . . . . .. . . .. . . . .. .. . . .. . . .. . . .. . . .. . . . . . . . .. . . .. 7/18 . . . .. . . .. .. Dark Matter Production Ω π = Ω cdm 12 10 m V /m π → ∞ 8 m π /f π 6 2 4 1 . 8 1. m π / f π 2 2. m V / m π 0 . 01 0 . 1 1 m π ❬●❡❱❪ Correct relic abundance requires m π / f π ≳ few

. . . . .. . .. .. . . .. . . .. . . .. . . . V decay visibly V decay invisibly Harigaya and Nomura (2016), Georgi (1992) m V . .. . .. .. . . .. . . .. . . . . . .. . . .. . . .. .. . .. . . .. . . .. . . .. .. . . 8/18 . . .. . . .. . . Mass Spectrum Vector mesons have masses close to the cutoff m V ∼ 4 π f π 1 ∼ m π / f π m π Correct relic abundances ⇒ m π / f π ≳ few ⇒ m V ≲ 2 m π ∗ ∗ up to quantum U (1) D corrections ⇒ m V ± > m V 0 If m V ≲ 2 m π , V decays to SM ⇒ three types of mass spectra: V 0 vis., V ± inv. A ′ A ′ A ′ V 0 , V ± V ± 2 m π 2 m π 2 m π V 0 V 0 , V ± π π π

. . .. . . .. . . .. . . .. . . .. .. .. . .. 9/18 Decay products boosted . .. . . . . . .. . . .. . . . .. .. . . . .. . . .. . . .. . . . . .. . . . .. . . . . .. .. . . .. . . .. A ′ Production in a Fixed Target Collision A ′ θ A ′ E beam = 2 . 3 GeV, m A ′ = 0 . 2 GeV e − γ 40000 E A ′ / E beam ∼ 1 − m A ′ / E beam 30000 Z 20000 10000 σ A ′ largest for m A ′ ≪ E beam 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 . 0 A ′ carries away ∼ E beam E A ′ /E beam 40000 30000 θ A ′ ∼ ( m A ′ / E beam ) 3/2 20000 ∼ E beam / m A ′ 10000 0 0 . 00 0 . 05 0 . 10 0 . 15 0 . 20 0 . 25 Emitted forward with θ A ′ ≪ 1 θ A ′

. . .. . . .. . . .. . . .. . . .. .. .. . . . .. . . .. . . .. . . .. . Vector mesons naturally long-lived . . .. . . .. . . .. . .. .. . . .. . . . . 10/18 . . .. . . .. . . .. . . .. . . . .. Decay Modes and Lifetimes α D = 10 − 2 , m V /m π = 3 ε = 10 − 3 , α D = 10 − 2 10 0 V π 10 0 10 − 1 ρπ + φπ 10 − 1 BR( A ′ → X ) cτ V [cm] 10 − 2 10 − 2 ππ V V 10 − 3 10 − 3 m V /m π = 1 . 8 m V /m π = 1 . 4 10 − 4 10 − 4 10 − 2 10 − 1 10 0 2 4 6 8 10 12 m V [GeV] m π /f π A ′ → V π, V → SM with O (10 % ) branching fraction!

. . .. . . .. . . .. . . .. . . .. . .. . . . .. . . .. . . .. . . .. . Can have DVs and large production rate . .. .. .. . . .. . . .. . . .. . . .. . . . . . . . .. . . .. 11/18 . .. . . .. . . .. Signals at Fixed Target Experiments Resonant e + e − e − A ′ V V ± e + . . . 2 m π V V 0 A ′ π π e − γ Z A ′ decays promptly, V gives displaced vertex

. . .. . . .. .. . .. . . .. . . .. . .. . .. 2016 data set: Uemura (2013) . .. . . . . . .. . . .. . . . .. .. . . .. . . .. . . . . . .. . . .. . . . .. . . . .. 12/18 . .. . . .. . .. . Heavy Photon Search HPS looks for A ′ → e + e − at JLab target e + e e E beam = 2 . 3 GeV , 4 µ m W target, 10 17 EOT ⇒ L ≈ 0 . 01 fb − 1 ECal Muon hodoscopes Tracker possible future run ( ∼ 2018 ): Measurement Trigger and PID E beam = 6 . 6 GeV , 8 µ m W target, 10 19 EOT ⇒ L ≈ 0 . 3 fb − 1