Heavy neutral leptons at ANUBIS work with M. Hirsch arXiv: 2001.04750 Zeren Simon Wang Seventh workshop of the LHC LLP Community May 26, 2020 Z.S. Wang Heavy neutral leptons at ANUBIS 1 / 13
Motivation Surge of interest in LLPs in recent years (Why we are here!) Existing future experiments for LLPs: SHiP, FASER, MATHUSLA, CODEX-b, AL3X, etc. [1909 . 13022] proposed a new option: ANUBIS One of the main drives for LLP searches: GeV-scale heavy neutral leptons (HNL) (1) the minimal scenario (2) extended scenarios: mLRSM, U (1) B − L , . . . Compare ANUBIS with other proposed experiments by studying HNLs Z.S. Wang Heavy neutral leptons at ANUBIS 2 / 13
Long-lived HNLs Observation of neutrino oscillations → non-zero neutrino mass Clearly beyond the SM Physics Various models including type-I seesaw add right-handed heavy neutrinos to the SM, which mix with ν α In type-I seesaw: | V α N | 2 ≃ m ν α / m N In models beyond that e.g. inverse seesaw, one can have larger | V α N | 2 while keeping m ν α small Free parameters: | V α N | 2 and m N Small | V α N | 2 and/or m N ⇒ long-lived HNLs Assume only one HNL within kinematic range of interest Assume HNL mixes only with one generation of active neutrinos Z.S. Wang Heavy neutral leptons at ANUBIS 3 / 13
Decay Number n N = n M · Br( M → n N ) · n n vis = n N · � P [ N in f.v.] � · Br( N → visible) N n MC N 1 � � P [ N in f.v.] � = P [ N i in f.v.] n MC N i =1 Use Pythia 8.243 to perform MC simulation in order to estimate � P [ N in f.v.] � Calculate P [ N i in f.v.] for each simulated HNL by geometrical consideration with the exponential decay law Assuming 0 background and 100% detector efficiency Z.S. Wang Heavy neutral leptons at ANUBIS 4 / 13
ANUBIS AN Underground Belayed In-Shaft search experiment [1909 . 13022] y l h x l v l seg v l h d v θ i IP IP z z d h d h l h [m] l v [m] d h [m] 18 56 5 L [fb − 1 ] d v [m] 24 3000 Z.S. Wang Heavy neutral leptons at ANUBIS 5 / 13
Individual decay probability, geometric estimate Lj ′ − Lj 3 δφ j i i − � λ z λ z i · (1 − e i ) P [ N i in f.v.] = 2 π · e j =1 l h / 2 δφ j = 2 arctan d v + (2 j − 1) / 2 · l seg v d h , d v + ( j − 1) · l seg � � � � v L j i = min max , d h + l h tan θ i d h , d v + j · l seg � � � � L j ′ v − L j i = min max , d h + l h i tan θ i λ z i = β z i γ i c τ β z i = | p z i / E | , γ i = E i / m N Z.S. Wang Heavy neutral leptons at ANUBIS 6 / 13
The minimal scenario e, µ, τ ν e ,µ,τ ν e,µ,τ W ± ν N ν N ν N Z h SM charged-current and neutral current: g V α N j ¯ ℓ α γ µ P L N j W − √ L = L µ + 2 g � V L α N j N j γ µ P L ν i Z µ α i V ∗ 2 cos θ W α, i , j B − , D − mesons: 2-body and 3-body decays Z → ν α + N t → W + b , W → l α + N W → l α + N h → ν α + N Z.S. Wang Heavy neutral leptons at ANUBIS 7 / 13
Results for the minimal scenario 10 − 4 10 − 4 10 − 4 10 − 4 FASER2 F A S E AL3X:250/fb R 10 − 5 10 − 5 10 − 5 10 − 5 10 − 6 10 − 6 10 − 6 10 − 6 NA62 | V αN | 2 | V αN | 2 CODEX-b 10 − 7 10 − 7 10 − 7 10 − 7 10 − 8 10 − 8 10 − 8 10 − 8 B-mesons D-mesons ANUBIS MATHUSLA DUNE 10 − 9 10 − 9 10 − 9 10 − 9 Z S H i P Top 10 − 10 10 − 10 10 − 10 10 − 10 W h 10 − 11 10 − 11 10 − 11 10 − 11 10 − 1 10 − 1 10 0 10 0 10 1 10 1 10 − 1 10 − 1 10 0 10 0 10 1 10 1 m N [GeV] m N [GeV] α = e , µ Z.S. Wang Heavy neutral leptons at ANUBIS 8 / 13
Left-right symmetric model Gauge group: SU (3) C × SU (2) L × SU (2) R × U (1) B − L g R � � d γ µ P R u + V R ¯ α N · ¯ l α γ µ P R N √ W − L = R µ + 2 g R + 1 − tan 2 θ W ( g L / g R ) 2 × � T 3 R + tan 2 θ W ( g L / g R ) 2 ( T 3 L − Q ) Z µ LR ¯ � � f γ µ f On-shell W R decay to N + l α Mesons decay via an off-shell W L with V α N Mesons decay via an off-shell W R , Z R negligible Assuming | V α N | 2 = m ν α / m N , too small to be relevant for either production or decay of N Z.S. Wang Heavy neutral leptons at ANUBIS 9 / 13
Results for the minimal LRSM 25 20 P i H S 15 A N U B MATHUSLA I S m W R [TeV] b 10 f / 0 5 2 : X 3 L A b - X E D O C 5 2 R E S A F MATHUSLA (on-shell W R ) FASER 10 0 10 0 10 1 10 1 m N [GeV] � 4 � � 4 | V α N | 2 → | V R α N | 2 � g R / g L m W L / m W R V R α N ∼ O (1), g L / g R = 1 Z.S. Wang Heavy neutral leptons at ANUBIS 10 / 13
U (1) B − L model Add a U (1) B − L to the SM gauge group H , Z ′ , right-handed neutrinos m N = 1 − 60 GeV , V α N = 10 − 9 − 10 − 2 m Z ′ = 6 TeV , g ′ x = m Z ′ / 2 g ′ 1 = 0 . 8 , ˜ 1 = 3 . 75 TeV , m H = 450 GeV , sin β = 0 . 3 [1804.04075] m 2 1 − 4 m 2 Γ( h → NN ) = 1 x 2 sin 2 β m h � 3 / 2 � N N m 2 2 ˜ 8 π h Γ( h → NN ) Br( h → NN ) = Γ( h → NN ) + cos 2 β Γ h SM σ ( pp → h → NN ) = cos 2 β · σ ( pp → h ) SM · Br( h → NN ) Decay via | V α N | 2 as the minimal scenario Z.S. Wang Heavy neutral leptons at ANUBIS 11 / 13
Restuls for U (1) B − L 10 − 4 10 − 4 10 − 5 10 − 5 10 − 6 10 − 6 10 − 7 10 − 7 10 − 8 10 − 8 10 − 9 10 − 9 10 − 10 10 − 10 | V αN | 2 10 − 11 10 − 11 0.01 eV < m ν < 0 . 3 eV 10 − 12 10 − 12 10 − 13 10 − 13 10 − 14 10 − 14 10 − 15 10 − 15 ANUBIS 10 − 16 10 − 16 MATHUSLA 10 − 17 10 − 17 10 − 18 10 − 18 0 10 20 30 40 50 60 m N [GeV] Z.S. Wang Heavy neutral leptons at ANUBIS 12 / 13
Conclusion LHC up to 3/ab integrated luminosity by 2035 Great discovery potential for LLPs Several proposals for future experiments for searching for LLPs: SHiP, FASER, MATHUSLA, CODEX-b, AL3X New proposal ANUBIS Studied long-lived HNLs in the minimal and extended scenarios ANUBIS comparable to MATHUSLA in sensitivity reach Thank You! Advertisement: CheckMATE2 with LLP searches recast to be released soon Z.S. Wang Heavy neutral leptons at ANUBIS 13 / 13
Backup: production cross sections b ¯ t ¯ M b c ¯ c h t W Z 6 × 10 8 2 × 10 10 6 × 10 1 1 × 10 3 2 . 1 × 10 5 6 . 4 × 10 4 σ M [pb] Table: (Rough) production cross section of each type of mother particles of the HNLs at LHC with √ s = 14 TeV. For c ¯ c we take into account all of D 0 , D + , D s , and D 0 ∗ mesons. For references see text. Z.S. Wang Heavy neutral leptons at ANUBIS 14 / 13
Backup: results for B − and D − production modes m N = 1 GeV Br( D → N + X ) · Br( N → +visible) m N = 1 GeV Br( B → N + X ) · Br( N → +visible) 10 − 6 10 − 6 10 − 6 10 − 6 10 − 7 10 − 7 10 − 7 10 − 7 10 − 8 10 − 8 10 − 8 10 − 8 10 − 9 10 − 9 10 − 9 10 − 9 10 − 10 10 − 10 10 − 10 10 − 10 10 − 11 10 − 11 10 − 11 10 − 11 ANUBIS ANUBIS 10 − 12 10 − 12 10 − 12 10 − 12 CODEX-b CODEX-b FASER2 FASER2 10 − 13 10 − 13 10 − 13 10 − 13 MATHUSLA MATHUSLA 10 − 14 10 − 14 10 − 14 10 − 14 10 0 10 1 10 1 10 2 10 2 10 3 10 3 10 4 10 4 10 5 10 5 10 6 10 6 10 7 10 7 10 8 10 0 10 1 10 1 10 2 10 2 10 3 10 3 10 4 10 4 10 5 10 5 10 6 10 6 10 7 10 7 10 8 10 − 2 10 − 2 10 − 1 10 − 1 10 0 10 8 10 − 2 10 − 2 10 − 1 10 0 10 − 1 10 8 cτ [m] cτ [m] Z.S. Wang Heavy neutral leptons at ANUBIS 15 / 13
Recommend
More recommend
