Dark Forces, Dark Matter, and the GeV- Scale Discovery Frontier - - PowerPoint PPT Presentation

Dark Forces, Dark Matter, and the GeV- Scale Discovery Frontier

Philip Schuster Perimeter Institute

New Light Weakly Coupled Particle Session CSS Conference July, 2013

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Nice Source Summarizing Broad Physics Program: – Intensity Frontier Meeting at Argonne (April 2013) (see posted talks)

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Considerable documentation to help with discussions over the next three days

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Outline

• Theory of Dark Forces & Motivation

– Fundamental Physics Motivation – Dark Matter Motivation – Precision Anomalies – Dark Matter Anomalies

• What has been achieved recently
• What will be achieved in next few years
• Goals for next 10 years

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We know there is dark matter ...but what is it? LHC and direct detection results challenge connection

• f dark matter to “weak-scale naturalness”

Beyond the Standard Model

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Completely new physics? extension of Standard Model? (axion, superpartner, ...)

p+, n, e–

Copernican Particle Physics?

? ? ? ... ?

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What do we actually know about the dark sector?

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U(1)D × ...

U(1)Y × SU(2)W × SU(3)s

Dark Sector ? Look for interactions allowed symmetry!

Beyond the Standard Model

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Known matter interacts through three gauge forces (strong, weak, and electromagnetic) LHC looking for new matter interacting through the same forces ...but what about matter that is not charged under these forces? Gauge- & Lorentz-invariance restrict possible interactions with such matter to high dimension operators. New sub- GeV matter can be consistent.

Beyond the Standard Model

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Higgs Portal

exotic rare Higgs decays?

Neutrino Portal

not-so-sterile neutrinos?

Vector Portal Axion Portal

1 fa aFµν ˜

F µν

1 2Y F Y µνF 0µν

The “Portals”

h |h|2|⇥|2 ν (hL)⇥

Searches can be organized around a small number of interactions allowed by Standard Model symmetries

kinetic mixing? axion-like particles?

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Focus of this talk

Higgs Portal

exotic rare Higgs decays?

Neutrino Portal

not-so-sterile neutrinos?

Vector Portal Axion Portal

1 fa aFµν ˜

F µν

1 2Y F Y µνF 0µν

The “Portals”

h |h|2|⇥|2 ν (hL)⇥

Searches can be organized around a small number of interactions allowed by Standard Model symmetries

axion-like particles?

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The Territory

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(A’ Electron/Muon Decays)

e−

e+

A′

0.001 0.01 0.1 1 10-5 10-4 10-3 10-2 mA' HGeVL e A' Æ Standard Model

APEXêMAMI Test Runs

U70 E141 E774 am, 5 s

am,±2 s favored

ae

BaBar KLOE

Orsay

Unexplored

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(A’ invisible “dark matter” Decays)

The Territory

A′

χ χ

(Izaguirre, Krnjaic, PS, Toro)

Unexplored

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GeV-Scale Discovery Frontier

? ? ? ? ?

Tremendous opportunity to explore GeV-Scale dark matter and weakly coupled physics with novel small-scale experiments!

What will we find?

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Outline

• Theory of Dark Forces & Motivation

– Fundamental Physics Motivation – Dark Matter Motivation – Precision Anomalies – Dark Matter Anomalies

• What has been achieved recently
• What will be achieved in next few years
• Goals for next 10 years

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1 2Y F Y µνF 0µν

Sources and Sizes of Kinetic Mixing

• If absent from fundamental theory, can still be

generated by perturbative (or non-perturbative) quantum effects – Simplest case: one heavy particle ψ with both EM charge & dark charge

generates ✏ ∼ e gD

16⇡2 log mψ

M∗ ∼ 10−2 − 10−4

A0

γ

ψ e gD

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1 2Y F Y µνF 0µν

Sources and Sizes of Kinetic Mixing

• If absent from fundamental theory, can still be

generated by perturbative (or non-perturbative) quantum effects – In Grand Unified Theory, symmetry forbids tree- level & 1-loop mechanisms. GUT-breaking enters at 2 loops

generating

A0

γ

ψ e gD

X

(→ if both U(1)’s are in unified groups)

✏ ∼ 10−3 − 10−5 10−7

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• sub-MeV: non-perturbative physics (like ΛQCD)
• MeV-to-GeV is motivated by g-2 and dark matter

anomalies

• Possible origin: related to MZ by small parameter

– e.g. supersymmetry+kinetic mixing ⇒ scalar coupling to SM Higgs, giving

Sources and Sizes of Mass Term

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mA0 ∼ √✏ MZ . 1GeV

a motivated target of opportunity

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“Top Down”-Motivated Region

(A’ Electron/Muon Decays)

0.001 0.01 0.1 1 10-5 10-4 10-3 10-2 mA' HGeVL e A' Æ Standard Model

APEXêMAMI Test Runs

U70 E141 E774 am, 5 s

am,±2 s favored

ae

BaBar KLOE

Orsay

One loop mixing Two loop mixing

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Projections vs. “top-down”

0.001 0.01 0.1 1 10-5 10-4 10-3 10-2 mA' HGeVL e A' Æ Standard Model

APEXêMAMI Test Runs

U70 E141 E774 am, 5 s

am,±2 s favored

ae

BaBar KLOE

Orsay

One loop mixing Two loop mixing One-loop region well covered below 500 MeV Two-loop region explored by HPS Mass reach should be extended, and gap should be closed

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Target of Opportunity? Precision Anomalies

Muon g-2

U(1)D coupling modifies (g-2)μ, with correct sign. ε~1-3 10–3 can explain discrepancy with Standard Model

[Pospelov ’08] [Hoeker ’10]

Muonic hydrogen

MeV-scale force carriers can explain the discrepancy between (μ-,p) Lamb shift [Pohl et al. 2010] and other measurements of proton charge radius. Requires couplings beyond kinetic mixing (lepton flavor-violating component)

[Tucker-Smith & Yavin, 1011.4922]

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Projections vs. Muon G-2

0.001 0.01 0.1 1 10-5 10-4 10-3 10-2 mA' HGeVL e A' Æ Standard Model

APEXêMAMI Test Runs

U70 E141 E774 am, 5 s

am,±2 s favored

ae

BaBar KLOE

Orsay

g-2 region for visible A’ decays can be completely explored

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Target of Opportunity? Direct-Detection Anomalies

CDMS collaboration, 1304.4279 Tracy Slatyer, IFW, April 2013 Argonne Meeting

Several light dark matter direct detection hints Dark matter interacting via dark photons is a viable explanation discussed at length in the literature

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Target of Opportunity? Direct-Detection Anomalies

A′

χ χ p p

⌅pχ ≈ 16⇤ D⇥2m2

pm2 χ

m4

A0(mχ + mp)2

≈ 1.2 × 10−40cm2 ✓ D⇥2 10−12 ◆ ✓GeV mA0 ◆4 ✓ D⇥2 10−12 ◆ ✓GeV mA0 ◆4 ∼ ΩDM Ωχ

Direct detection equally sensitive to any DM component So best fit is given by:

(ratio of densities)

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Target of Opportunity? Direct-Detection Anomalies

0.001 0.01 0.1 1 10-5 10-4 10-3 10-2 mA' HGeVL e A' Æ Standard Model

APEXêMAMI Test Runs

U70 E141 E774 am, 5 s

a

m,±2 s

f a v

• r

e d

ae

BaBar KLOE

Orsay

Region of interest depends on and “DM” partial fraction

Ωχ/ΩDM

αD

αD = 10−2α Ωχ/ΩDM = 10−4

αD = α Ωχ/ΩDM = 10−4 αD = α Ωχ/ΩDM = 1

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0.001 0.01 0.1 1 10-5 10-4 10-3 10-2 mA' HGeVL e A' Æ Standard Model

APEXêMAMI Test Runs

U70 E141 E774 am, 5 s

am,±2 s favored

ae

BaBar KLOE

Orsay 23

αD = 10−2α Ωχ/ΩDM = 10−4

αD = α Ωχ/ΩDM = 10−4 αD = α Ωχ/ΩDM = 1

Will start to cover large direct-detection region, but will need to do better

Projections vs. Direct-Detection

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Target of Opportunity? Cosmic Ray Anomalies

Tracy Slatyer, IFW, April 2013 Argonne Meeting

Increasing positron fraction may be due to DM annihilation/decay to A’s

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Target of Opportunity? Cosmic Ray Anomalies

Tracy Slatyer, IFW, April 2013 Argonne Meeting

Fits to cosmic ray spectra prefer A‘ masses above the muon decay threshold (>210 MeV)

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Target of Opportunity? Cosmic Ray Anomalies

0.001 0.01 0.1 1 10-5 10-4 10-3 10-2 mA' HGeVL e A' Æ Standard Model

APEXêMAMI Test Runs

U70 E141 E774 am, 5 s

a

m,±2 s

f a v

• r

e d

ae

BaBar KLOE

Orsay

Preferred by fits of cosmic ray data to ~few TeV DM annihilating to A’s

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Projections vs. DM Cosmic Ray

0.001 0.01 0.1 1 10-5 10-4 10-3 10-2 mA' HGeVL e A' Æ Standard Model

APEXêMAMI Test Runs

U70 E141 E774 am, 5 s

am,±2 s favored

ae

BaBar KLOE

Orsay

HPS and APEX will make progress, but will need to do better Non-minimal dark sector or modified propagation consistent with lighter A’

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sub- 500 MeV WIMP search using MiniBooNE

(see: arXiv:1211.2258 for proposal)

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Projections

(A’ invisible “dark matter” Decays)

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Projections

(A’ invisible “dark matter” Decays)

(Izaguirre, Krnjaic, PS, Toro)

Potential searches using electron fixed-target

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10-Year Goals for “Heavy- Photon” Physics

• “Visible” Decays

– (gμ-2)–motivated region (<100% branching?) – Full perturbative coupling range (ε≳10-5) over widest mass range possible – Sensitivity to muons and pions to extend mass reach – Sensitivity to multi-stage dark sector decays

• “Invisible” decays

– (gμ-2)–motivated region (<100% branching?) – Full perturbative coupling range (ε≳10-5) over widest mass range possible – Probe dark matter masses from MeV to GeV range

e−

e+

A′

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A′

χ χ

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Probe anomaly driven scenarios from precision, DM direct detection, and cosmic ray hints In the process, discover and study True Muonium, try to carry out precision muon studies (parity violation?), probe extended Higgs sectors...etc. We either discover new forces (or DM), or we close up a big window into dark sector physics at sub-GeV scales

10-Year Goals for “Heavy- Photon” Physics

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Conclusions

• Dark Forces are an exciting window into physics

far beyond the Standard Model

– Possible connections to dark matter, muon g-2, and physics at very high energies

• Small-scale & novel experiments are pioneering

the exploration of this physics

– Will explore large new physics territory for direct A’ production and decay and discover rare SM physics

• Potential opportunities at many labs to directly

produce dark matter and search for invisible A’ decays with unique sensitivity

• 10-year physics program continuing to leverage

existing facilities has exciting discovery prospects

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Thanks!

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