Teruki Kamon Mitchell Institute for Fundamental Physics and Astronomy

Texas A&M University

Searching for Long-Lived Particles at the LHC:

Fifth workshop on the LHC Long-Lived Particle (LLP) Community,

(https://indico.cern.ch/event/792346/overview)

CERN, 27-29 May 2019

1May 27, 2019 Kinetic Mixing

[Credits]

Images of Baryon Acoustic Bscillations with Cosmic Microwave Background

by E.M. Huff, the SDSS-III team, and the South Pole Telescope team. Graphic

by Zosia Rostomian (Lawrence Berkeley National Laboratory)

Image of Neutrino Astrophysics, taken from https://astro.desy.de/

Image of the LHC by CERN Photo

Image of Bullet Cluster by NASA/ Chandra X-ray Center

Probing Kinetic Mixing Term

of Dark Gauge Boson

at the LHCCollaboration:

Mohammad Abdullah (Mitchell Institute)

Bhaskar Dutta (Mitchell Institute)

Teruki Kamon (CMS/Mitchell Institute)

Marcus Hohlmann (CMS/FIT)

Adrian Thompson (CMS/Mitchell Institute)

A simple extension of the standard model involves adding a "dark" U(1) gauge group

that is broken by a dark Higgs vev. The "dark vector" 𝑍𝐷 can then kinetically mix withthe 𝑈(1)𝐵 gauge boson, and the "dark Higgs" 𝑆 (or ℎ𝑆) can mix with the SM doubletHiggs via the Higgs portal |H|2|S|2 operator. This can induce a variety of exotic Higgs

decays like:

ℎ → 𝑍𝑍𝐷 (if kinetic mixing dominates)ℎ → 𝑍𝐷𝑍𝐷 (if higgs mixing dominates)ℎ → 𝑆𝑆 (if higgs mixing dominates)

http://insti.physics.sunysb.edu/~curtin/hahm_mg.html

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Kinetic Mixing with Dark Gauge Boson

Note: this is not Feynman diagram

Kinetic Mixing by ATLAS and CMS

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MC samples m(𝜸𝑫) = 0.25 –58 GeV 𝑐𝜏 = 0 –100 mm m(𝑵𝟏) = 10, 60 GeV, m(𝒏𝑫) = 1 GeV

Unknown

branching

fractions

Unknown

branching

fractions

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𝑝𝑝 → ℎ → 𝑍𝑍𝑑(or 𝑎𝑎) → 4𝓁 ; 𝑝𝑝 → 𝑍𝑑 → 𝓁𝓁; 𝑝𝑝 → 𝑍 → 𝜇𝜇; 𝑍𝑑 → 4𝓁

Other Representative Processes

Independent of the Higgs portal

|H|2|S|2 operator

𝒁′ as ”𝜸𝒅 or 𝒁𝒅” Search FrameworkPhysics of dark gauge boson (𝜸𝑑 or 𝑍𝑑) can be studied via a framework of aspin-1 particle (𝒁′) which couples to first- and second-generation fermions.

o Associated production with ISR jet/photon or the SM weak

gauge boson (V = W or Z) will probe the mixing term

independently of the Higgs portal |H|2|S|2 operator.

o Larger signal cross sections, compared to processes with

the Higgs boson decays.

o [Trigger] A standard mono-jet or mono-photon or mutilepton

trigger (w/o vertex constraint on leptons).

o [Main backgrounds] g(photon)+𝛾∗ (𝑝𝑇(𝑔 𝑜𝑟 𝛾) > 200 GeV) or V+𝛾∗ (𝑝𝑇(𝑉) >

20 GeV), followed by 𝛾∗ → 𝜇𝜇. But they should be suppressed by a lifetime cut. Also 𝑔∗ → 𝑏𝑏 → 𝜇𝜇 + 𝑋 (we need an isolation study.)

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A basic idea on direct production is stated in “Non-Abelian

Dark Sectors and Their Collider Signatures”, Matthew

Baumgart, Clifford Cheung, Joshua T. Ruderman, Lian-Tao

Wang, and Itay Yavin, JHEP 04 (2009) 014, 10.1088/1126-

6708/2009/04/014 [arXiv:0901.0283]. See Fig. 11.

https://arxiv.org/ct?url=https%3A%2F%2Fdx.doi.org%2F10.1088%2F1126-6708%2F2009%2F04%2F014&v=50ff5ccehttps://arxiv.org/abs/0901.0283

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𝒁′ Associate Production Processes

𝑝𝑇(𝑔) > 200 GeV

𝑝𝑇(𝛾) > 200 GeV

𝑝𝑇(𝑉) > 20 GeV

𝑝𝑇(𝑉) > 20 GeV

Low mass 𝑍′ could be probed by V+𝑍′, as an angular separation of leptons in highlyboosted lighter dark gauge boson may be a problem in high 𝑝𝑇(𝑔 𝑜𝑟 𝛾) trigger. For𝑝𝑇 ≳ 200 GeV, an opening angle of approximately 𝜃~ Τ𝑚𝛾′ 𝑝𝑇 < 0.00125 for M = 0.25

GeV.

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Kinematics in 𝒁′ Associate Production𝒑𝑻(j,𝜸) > 200 GeV or 𝒑𝑻(𝝁 from W, Z) > 20 GeV

M = 1 GeV M = 10 GeV

𝒑𝑻(𝝁𝝁)

∆𝝋(𝝁𝝁)

𝒑𝑻(𝝁𝝁)

∆𝝋(𝝁𝝁)

MadGraph+Delphes

Adrian Thompson

Mohammad Abdullah

𝜃~ Τ𝑚𝛾′ 𝑝𝑇 < 0.005

for 1 GeV mass

𝝈∙𝑨∙ℒ

𝝈∙𝑨∙ℒ

𝝈∙𝑨∙ℒ

𝝈∙𝑨∙ℒ

[U(1)𝐿𝜇 − 𝐿𝜏 gauge bosons] A search for Z′ in 4μ final state, PLB 792 (2019) 345, EXO

18-008, CMS AN-17/321, arXiv:1808.03684

[Refs: arxiv:1808.03647, arxiv:1712.10022]

70 GeV

Complementary Search

+ quark sectors?

?

[CMS, PLB 792 (2019) 345; 1808.03684] The

4μ analysis can set limits on 𝑔𝜇 for masses

down to 10 GeV.

𝒈

The limits will depend on how many decay

channels the Z‘ has in our model.

There are some limits from related searches,

but not on the same process directly.

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Summary[Complementary] The mixing term can

be probed via associate production with

ISR jet/photon or the SM weak gauge

boson (V = W or Z), independently of

the Higgs portal |H|2|S|2 operator.

[Wide mass range] Low mass 𝑍′ can besearched using V+𝑍′ (𝑝𝑇(𝑉) > 20 GeV),as angular separation of leptons in

highly boosted lighter dark gauge boson

may be a problem in 𝑝𝑇 𝑔 𝑜𝑟 𝛾 > 200 −500 GeV.

“Hunting All the Hidden Photons”, Martin

Bauer, Patrick Foldenauer, and Joerg Jaeckel,

JHEP 07 (2018) 094

BACKUP

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Cross Section and AcceptanceMadGraph+Delphes

Adrian Thompson

Mohammad Abdullah

Thinking of Direct ProductionA basic idea on direct production is stated in “Non-Abelian Dark Sectors and

Their Collider Signatures”, Matthew Baumgart, Clifford Cheung, Joshua T.

Ruderman, Lian-Tao Wang, and Itay Yavin, JHEP 04 (2009) 014,

10.1088/1126-6708/2009/04/014 [arXiv:0901.0283].

See Fig. 11. X is not specified. They envisioned to trigger those events with

single/dimuon triggers, referring to CMS Level 1 dimuon trigger (2 muons with 𝑝𝑇 > 3GeV in |η| < 2.4) or single muon trigger (1 muon with 𝑝𝑇 > 7 GeV and |η| < 2.4). Thus𝑝𝑇 ≳ 10 GeV, resulting in an opening angle of approximately 𝜃~ Τ𝑚𝛾′ 𝑝𝑇 < 0.025 for 10

GeV 𝑝𝑇, 0.25 GeV mass.

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https://arxiv.org/ct?url=https%3A%2F%2Fdx.doi.org%2F10.1088%2F1126-6708%2F2009%2F04%2F014&v=50ff5ccehttps://arxiv.org/abs/0901.0283

On Decay ModesIf Gd includes SU(2)d, the decay modes are more complex.

See Fig. 9 of “Non-Abelian Dark Sectors and Their Collider Signatures”, Matthew

Baumgart, Clifford Cheung, Joshua T. Ruderman, Lian-Tao Wang, and Itay Yavin,

JHEP 04 (2009) 014, 10.1088/1126-6708/2009/04/014 [arXiv:0901.0283].

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https://arxiv.org/ct?url=https%3A%2F%2Fdx.doi.org%2F10.1088%2F1126-6708%2F2009%2F04%2F014&v=50ff5ccehttps://arxiv.org/abs/0901.0283

Probing Kinetic Mixing Term at LHC“Hunting All the Hidden Photons”, Martin Bauer, Patrick Foldenauer, and

Joerg Jaeckel, JHEP 07 (2018) 094

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Can we search at ATLAS + CMS?𝝐𝒆

𝑴𝑨′

Physics of dark gauge boson (𝜸𝑑 or 𝑍𝑑) can be studied via a framework of a spin-1particle (𝒁′) which couples to first- and second-generation fermions.

[U(1)𝑳𝝁 − 𝑳𝝉 gauge bosons] A search for Z′ in 4μ final state, PLB 792 (2019)

345, EXO 18-008, CMS AN-17/321, arXiv:1808.03684[Refs: arxiv:1808.03647, arxiv:1712.10022]

70 GeV

Example: Constraints on 𝒈𝝁 on 𝒁′

[CMS, PLB 792 (2019) 345; 1808.03684] The

4μ analysis can set limits on 𝑔𝜇 for masses

down to 10 GeV.

Also see [CMS, JHEP 01 (2018)

097;1710.00159] Z’ with AK8 jet 𝑝𝑇 > 500 GeV (against another high 𝑝𝑇 ISR jet) for leptophobic Z' that can set limits on 𝑔𝑞 down

to 𝑚(𝑍′) = 50 GeV.

𝒈

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“Coherent elastic neutrino nucleus scattering as a probe of a Z′ through kinetic and mass mixing

effects” Mohammad Abdullah, James B. Dent, Bhaskar Dutta, Gordon L. Kane, Shu Liao, and

Louis E. Strigari, Phys.Rev. D98 (2018) 015005

𝝐𝒁 𝝐𝑩

Connection with CEvNS