High-intensity probes of dark sector particles Stefania Gori UC - - PowerPoint PPT Presentation

High-intensity probes of dark sector particles

Stefania Gori

UC Santa Cruz

DESY Virtual Theory Forum, 2020 September 23, 2020

What is a dark sector particle?

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Our visible universe The dark universe

Dark Matter

dark fermions?

Any particle that does not interact through the Standard Model (SM) forces.

MeV GeV TeV

Thermal DM Dark sectors WIMPs

The DM mass scale

axions sterile neutrinos Primordial black holes

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Why a dark sector? (DM)

Need for new particles in addition to DM (the “mediator(s)”)

MeV GeV TeV

Thermal DM Dark sectors WIMPs

The DM mass scale

axions sterile neutrinos Primordial black holes

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Why a dark sector? (DM)

Dark sectors are needed Lee-Weinberg bound (~ few GeV)

New dark interactions

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Why a dark sector? (beyond DM)

Beyond the DM motivation, many other open problems in particle physics let us think about dark particles.

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Models to address the strong CP problem. Axions and axion-like particles;

Models to address the gauge hierarchy problem (relaxion); SUSY extended models (Next-to-Minimal-Supersymmetric-Standard-Model); Models for baryogengesis; Models for neutrino mass generation; Models addressing anomalies in data

((g-2)μ, galactic center excess for Dark Matter, Xenon1T anomaly, B-physics anomalies, KOTO anomaly, …).

Some of these particles are naturally light thanks to approximate global symmetries.

Beyond the DM motivation, many other open problems in particle physics let us think about dark particles.

Why a dark sector? (beyond DM)

Dark Matter dark fermions?

Only a few interactions exist that are allowed by Standard Model symmetries:

Dark photon Neutrino

A’ S N

“portal interactions” “mediators”

How to gain access to the dark sector?

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a

Higgs Axion “mediators”

Dark Matter dark fermions?

Only a few interactions exist that are allowed by Standard Model symmetries:

Dark photon Neutrino

A’ S N

“portal interactions” “mediators”

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a

Higgs “mediators”

+ possible new dark gauge bosons

• btained gauging e.g. B-L, Lμ-Lτ, …

How to gain access to the dark sector?

Axion

A broad program of searches

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Vigorous effort of the community proposing new experiments & measurements The LHC Flavor-factories Fixed target / neutrino experiments Beam Dump/shield

DM/dark sectors

e/p

(high intensity)

Novel search strategies are needed!

dark particle

p p

Unique access to dark sectors!

6

volume Decay Detector

Complementarity with direct and indirect DM detection experiments

1. 2. 3.

Final states to look for

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Invisible, non-SM Visible, SM

Dark Matter production Production of portal- mediators that decay to SM particles Systematically exploring the portal coupling to SM particles Producing stable particles that could be (all or part

• f) Dark Matter

X mediator X SM SM SM mediator SM

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SM SM

Mixed visible-invisible

Production of “rich” dark sectors Testing the structure

• f the dark sector

Final states to look for

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Invisible, non-SM Visible, SM

Dark Matter production Production of portal- mediators that decay to SM particles Systematically exploring the portal coupling to SM particles Producing stable particles that could be (all or part

• f) Dark Matter

X mediator X SM SM SM mediator SM Non-secluded DM models X X SM SM mediator

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X X mediator mediator Secluded DM models SM SM Examples of DM models:

Inelastic DM models Strongly interacting DM models, …

Mixed visible-invisible

Production of “rich” dark sectors Testing the structure

• f the dark sector

• 1. Production of dark particles at the LHC

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dark particle

p p

Direct production

LHCb covers an important role if the dark particle is light

+ proposed additional detectors: MATHUSLA, FASER, CODEX-b, …

Dark particles can be produced in the same way as SM particles since they mix

Mixing of the dark photon with the SM photon/Z boson Mixing of the dark Higgs with the SM Higgs Mixing of the dark neutrino with the SM neutrinos

• 1. Production of dark particles at the LHC

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Easy to obtain sizable branching ratios

(SM Higgs width is tiny!)

dark particle

p p

Higgs exotic decays

(if light)

Direct production

LHCb covers an important role if the dark particle is light

+ proposed additional detectors: MATHUSLA, FASER, CODEX-b, … Huge statistics still to come:

Dark particles can be produced in the same way as SM particles since they mix

Mixing of the dark photon with the SM photon/Z boson Mixing of the dark Higgs and the SM Higgs Mixing of the dark neutrino and the SM neutrinos

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Global symmetry of the scalar potential (e.g. SU(4)) The SM Higgs is a (massless) Nambu-Goldstone boson SMA x SMB x Z2

Loop corrections to the Higgs mass:

top yA yA HA HA twin-top yB yB HB HB

Loop corrections to mass are SU(4) symmetric no quadratically divergent corrections!

An example: Twin Higgs models

~SM Higgs doublet Twin Higgs doublet

9 Chacko, Goh, Harnik, 0506256

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Global symmetry of the scalar potential (e.g. SU(4)) The SM Higgs is a (massless) Nambu-Goldstone boson SMA x SMB x Z2

Loop corrections to the Higgs mass:

top yA yA HA HA twin-top yB yB HB HB

Loop corrections to mass are SU(4) symmetric no quadratically divergent corrections!

An example: Twin Higgs models

~SM Higgs doublet Twin Higgs doublet

• 1. SU(4) and Z2 are (softly) broken:

Mixing between the SM and the twin Higgs

Higgs portal

• 2. Glue-balls can mix with the

SM Higgs, HA

9 Chacko, Goh, Harnik, 0506256

S.Gori 10 Craig et al., 1501.05310

Glue-ball. O++ mixes with the 125 GeV Higgs and decays typically displaced. Twin Higgs

HT Signature: HT → >= 2 displaced

Long-lived signatures from twin Higgs decays

S.Gori 10 Craig et al., 1501.05310 Alipour-Fard, Craig, SG, Koren, Redigolo, 1812.09315

Twin Higgs mass [TeV]

Twin Higgs → hh

(prompt)

Long-lived signatures from twin Higgs decays

Twin Higgs

HT

Glue-ball. O++ mixes with the 125 GeV Higgs and decays typically displaced.

Signature: HT → >= 2 displaced

125 GeV Higgs coupling measurements

S.Gori 10 Craig et al., 1501.05310 Alipour-Fard, Craig, SG, Koren, Redigolo, 1812.09315

Twin Higgs mass [TeV]

125 GeV Higgs coupling measurements

Long-lived signatures from twin Higgs decays

Twin Higgs → glue-balls: (long lived) CMS inner tracker analysis; CMS beam pipe analysis; ATLAS muon spectrometer analysis The relative strength depends

• n other parameters of the theory

Glue-ball. O++ mixes with the 125 GeV Higgs and decays typically displaced.

Signature: HT → >= 2 displaced

Twin Higgs

HT

Twin Higgs → hh

(prompt) + 125 GeV Higgs exotic decays to glue-balls

• 2. The precision frontier @ flavor factories

B-factories Kaon- factories Pion- factories A big jump in luminosity is expected in the coming years

Past/Present Future

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B-factories Kaon- factories Pion- factories

LHCb: more than ~ 1012 b quarks produced so far; Belle (running until 2010): ~109 BB-pairs were produced. ~40 times more b quarks will be produced by the end of the LHC; ~50 times more BB-pairs will be produced by Belle-II. E949 at BNL: ~1012 K+ (decay at rest experiment); E391 at KEK: ~1012 KL NA62 at CERN: ~1013 K+ by the end of its run (decay in flight experiment); KOTO at JPARC: ~1013 KL by the end of its run PIENU experiment at TRIUMF: ~1011 pi+ (still analyzing data)

?

Past/Present Future

A big jump in luminosity is expected in the coming years

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• 2. The precision frontier @ flavor factories

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Plenty of dark particles can be produced from meson decays

B-factories Kaon- factories Pion- factories

LHCb: more than ~ 1012 b quarks produced so far; Belle (running until 2010): ~109 BB-pairs were produced. ~40 times more b quarks will be produced by the end of the LHC; ~50 times more BB-pairs will be produced by Belle-II. E949 at BNL: ~1012 K+ (decay at rest experiment); E391 at KEK: ~1012 KL NA62 at CERN: ~1013 K+ by the end of its run (decay in flight experiment); KOTO at JPARC: ~1013 KL by the end of its run PIENU experiment at TRIUMF: ~1011 pi+ (still analyzing data)

?

Past/Present Future

A big jump in luminosity is expected in the coming years

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• 2. The precision frontier @ flavor factories

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Plenty of dark particles can be produced from meson decays

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Kaon rare decays: K → π ν ν

Only operator in the SM

+ box diagrams

Very rare! Access to NP

Brod, Gorbahn, Stamou 1009.0947; Buras, Buttazzo, Girbach-Noe, Knegjens, 1503.02693

SM

3 events in the signal region Expected number of events: 0.05±0.02 → 1.05±0.28

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Kaon rare decays: K → π ν ν

Only operator in the SM

+ box diagrams

Brod, Gorbahn, Stamou 1009.0947; Buras, Buttazzo, Girbach-Noe, Knegjens, 1503.02693

SM Exp.

NA62: Analysis of the 2018 data 20 events observed in total

3.5σ evidence

Marchevski talk @ ICHEP

KOTO: Analysis of the 2016-2018 data

(pre → post-ICHEP)

talk by Shimizu @ ICHEP

Very rare! Access to NP

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Testing axion-like-particles at NA62 & KOTO

ALP mixing with SM mesons (pions, etas) The ALP-pion and ALP-eta mixing will induce an effective K-π-ALP coupling (K → aπ) an ALP coupling to photons (a → γγ)

We can search for

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Testing axion-like-particles at NA62 & KOTO

ALP mixing with SM mesons (pions, etas) The ALP-pion and ALP-eta mixing will induce an effective K-π-ALP coupling (K → aπ) an ALP coupling to photons (a → γγ)

We can search for

ALP lifetime (in meters), BR(KL→ π a), BR(K+→ π+ a)

SG, G. Perez, K. Tobioka, 2005.05170

This bound comes from precision pion experiments (new interpretation of existing PIBETA data for )

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The reach on the ALP parameter space

electron/proton beam dump GlueX,

Aloni et al., 1903.03586

L E P

e+e- →γ a, a → γγ (collimated) In gray, we show all present constraints

• W. Altmannshofer, SG, D. Robinson,

1909.00005 SG, G. Perez, K. Tobioka, 2005.05170 14

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Several running/proposed experiments to search for prompt or long lived dark sector particles. Let’s mention a few of them. Disclaimer: this is not an exhaustive list.

• 3. Fixed-target experiments

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Visible final states

Excellent for detecting low-mass displaced visible dark particles e.g. dark photon production:

Berlin, SG, Schuster, Toro, 1804.00661

See also LongQuest proposal:

Tsai, De Niverville, Liu, 1908.07525

p-beam: SpinQuest/DarkQuest @ Fermilab

e,p e,p

γ

Near forward detectors. Examples:

e-beam: HPS @ JLAB, MAGIX @ MESA

• 3. Fixed-target experiments

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Invisible final states

NA64, LDMX, M3

Excellent for detecting low-mass invisible dark particles Unique capability to “image” individual beam particles electron and muon beams

Missing momentum or energy DM beam dump BDX, DarkMESA

DM-detector scattering

Izaguirre, Krnjaic, Schuster, Toro, 1307.6554

• 3. Fixed-target experiments

Examples:

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The reach on visible & invisible dark sectors

S.Gori The Belle-II physics book, 1808.10567

LHCb, Babar

Berlin, SG, Schuster, Toro, 1804.00661 17

Visible Invisible

Conclusions & Outlook

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Dark sector particles arise in a large variety of beyond the Standard Model theories. Unique opportunity to probe dark sectors at high-intensity experiments: LHC as a high-intensity machine Flavor factories Fixed target experiments Complementarity with direct detection & astrophysical probes

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How do the NA62 & KOTO results compare?

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2015 run 1σ

Marchevski talk @ ICHEP

~ KOTO new “central value”

Light (< mK) new physics would be required if this will turn out to be a “real” anomaly

It cannot be described by an EFT

• 2. GG-coupled ALP simplified model

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Kinetic mixing with the pion of the SM Kinetic mixing and mass mixing with the eta of the SM Kinetic mixing Mass mixing

(mass mixing is due to the eta-eta’ mixing, θηη’)

Christ et al., 1002.2999

ALP interactions with SM mesons

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Theory prediction for K → π a

At low energy, the two operators responsible for s → d transitions are

no ALP-eta mixing n

• A

L P

• e

t a m i x i n g

K+ → a π+ KL → a π0

Note: possible additional UV contributions

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The ALP-pion and ALP-eta mixing will induce an effective K-π-ALP coupling (K → aπ) an ALP coupling to photons (a → γγ)

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