Heavy neutral leptons at ANUBIS work with M. Hirsch arXiv: - - PowerPoint PPT Presentation

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 να In type-I seesaw: |VαN|2 ≃ mνα/mN In models beyond that e.g. inverse seesaw, one can have larger |VαN|2 while keeping mνα small Free parameters: |VαN|2 and mN Small |VαN|2 and/or mN ⇒ 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

nN = nM · Br(M → n N) · n nvis

N

= nN · P[N in f.v.] · Br(N → visible) P[N in f.v.] = 1 nMC

N nMC

N

• i=1

P[Ni in f.v.] Use Pythia 8.243 to perform MC simulation in order to estimate P[N in f.v.] Calculate P[Ni 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]

dv dh lv lh θi z y IP lseg

v

dh lh z x IP

lh [m] lv [m] dh [m] 18 56 5 dv [m] L [fb−1] 24 3000

Z.S. Wang Heavy neutral leptons at ANUBIS 5 / 13

Individual decay probability, geometric estimate

P[Ni in f.v.] =

3

• j=1

δφj 2π · e

−Lj i λz i · (1 − e

−

Lj′ i λz i )

δφj = 2 arctan lh/2 dv + (2j − 1)/2 · lseg

v

Lj

i = min

• max
• dh, dv + (j − 1) · lseg

v

tan θi

• , dh + lh
• Lj′

i = min

• max
• dh, dv + j · lseg

v

tan θi

• , dh + lh
• − Lj

i

λz

i = βz i γi c τ

βz

i = |pz i /E|, γi = Ei/mN

Z.S. Wang Heavy neutral leptons at ANUBIS 6 / 13

The minimal scenario

W ± νN e, µ, τ Z νN νe,µ,τ h νN νe,µ,τ

SM charged-current and neutral current: L = g √ 2 VαNj ¯ ℓαγµPLNjW −

Lµ +

g 2 cos θW

• α,i,j

V L

αiV ∗ αNjNjγµPLνiZµ

B−, D−mesons: 2-body and 3-body decays Z → να + N t → W + b, W → lα + N W → lα + N h → να + N

Z.S. Wang Heavy neutral leptons at ANUBIS 7 / 13

Results for the minimal scenario

10−1 10−1 100 100 101 101 mN [GeV] 10−11 10−11 10−10 10−10 10−9 10−9 10−8 10−8 10−7 10−7 10−6 10−6 10−5 10−5 10−4 10−4 |VαN|2

B-mesons D-mesons Z Top W h

10−1 10−1 100 100 101 101 mN [GeV] 10−11 10−11 10−10 10−10 10−9 10−9 10−8 10−8 10−7 10−7 10−6 10−6 10−5 10−5 10−4 10−4 |VαN|2

ANUBIS AL3X:250/fb NA62 DUNE F A S E R FASER2 S H i P MATHUSLA CODEX-b

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 L = gR √ 2

• ¯

dγµPRu + V R

αN · ¯

lαγµPRN

• W −

Rµ +

+ gR

• 1 − tan2 θW (gL/gR)2 ×

Z µ

LR ¯

f γµ

• T3R + tan2 θW (gL/gR)2 (T3L − Q)
• f

On-shell WR decay to N + lα Mesons decay via an off-shell WL with VαN Mesons decay via an off-shell WR, ZR negligible Assuming |VαN|2 = mνα/mN, 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

100 100 101 101 mN [GeV] 5 10 15 20 25 mWR [TeV]

A N U B I S FASER F A S E R 2 MATHUSLA MATHUSLA (on-shell WR) S H i P C O D E X

• b

A L 3 X : 2 5 / f b

|VαN|2 → |V R

αN|2

gR/gL 4 mWL/mWR 4 V R

αN ∼ O(1), gL/gR = 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 mN = 1 − 60 GeV, VαN = 10−9 − 10−2 mZ ′ = 6 TeV, g′

1 = 0.8, ˜

x = mZ ′/2g′

1 = 3.75 TeV,

mH = 450 GeV, sin β = 0.3 [1804.04075] Γ(h → NN) = 1 2 m2

N

˜ x2 sin2 β mh 8π

• 1 − 4m2

N

m2

h

3/2 Br(h → NN) = Γ(h → NN) Γ(h → NN) + cos2 β Γh

SM

σ(pp → h → NN) = cos2 β · σ(pp → h)SM · Br(h → NN) Decay via |VαN|2 as the minimal scenario

Z.S. Wang Heavy neutral leptons at ANUBIS 11 / 13

Restuls for U(1)B−L

10 20 30 40 50 60 mN [GeV] 10−18 10−18 10−17 10−17 10−16 10−16 10−15 10−15 10−14 10−14 10−13 10−13 10−12 10−12 10−11 10−11 10−10 10−10 10−9 10−9 10−8 10−8 10−7 10−7 10−6 10−6 10−5 10−5 10−4 10−4 |VαN|2

ANUBIS MATHUSLA

0.01 eV < mν < 0.3 eV 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

M b¯ b c ¯ c h t¯ t W Z σM [pb] 6 × 108 2 × 1010 6 × 101 1 × 103 2.1 × 105 6.4 × 104

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 D0, D+, Ds, and D0∗ mesons. For references see text.

Z.S. Wang Heavy neutral leptons at ANUBIS 14 / 13

Backup: results for B− and D−production modes

10−2 10−2 10−1 10−1100 100 101 101 102 102 103 103 104 104 105 105 106 106 107 107 108 108 cτ [m] 10−14 10−14 10−13 10−13 10−12 10−12 10−11 10−11 10−10 10−10 10−9 10−9 10−8 10−8 10−7 10−7 10−6 10−6 Br(B → N + X) · Br(N → +visible)

ANUBIS CODEX-b FASER2 MATHUSLA

mN = 1 GeV

10−2 10−2 10−1 10−1100 100 101 101 102 102 103 103 104 104 105 105 106 106 107 107 108 108 cτ [m] 10−14 10−14 10−13 10−13 10−12 10−12 10−11 10−11 10−10 10−10 10−9 10−9 10−8 10−8 10−7 10−7 10−6 10−6 Br(D → N + X) · Br(N → +visible)

ANUBIS CODEX-b FASER2 MATHUSLA

mN = 1 GeV

Z.S. Wang Heavy neutral leptons at ANUBIS 15 / 13