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New Muon Beam Missing Momentum Experiments @ FNAL ( g 2) & - - PowerPoint PPT Presentation
New Muon Beam Missing Momentum Experiments @ FNAL ( g 2) & - - PowerPoint PPT Presentation
New Muon Beam Missing Momentum Experiments @ FNAL ( g 2) & Dark Matter Yoni Kahn, Gordan Krnjaic Nhan Tran, Andrew Whitbeck arXiv:1803.XXXXX Precision Science Discussion Mar 20, 2018 Overview & Motivation 1) Model independent
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Overview & Motivation
1) Model independent test of g-2 anomaly 2) Probe models of muon-philic dark matter
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Muon Anomalous Magnetic Moment
Mangano, Keshavarzi, Nomura, Teubner 1802.02995
Theory updates have only widened disagreement Remains a great hint of possible new physics
aµ ≡ aµ(obs) − aµ(SM) = (31.3 ± 7.7) × 10−10 aµ ≡ aµ(obs) − aµ(SM) = (28.8 ± 8.0) × 10−10
Jegerlehner 1705.00263
Longstanding ∼ 3.7 − 4.1σ anomaly in (g − 2)µ
Soon FNAL g-2 experiment will shrink error bars
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Many popular new physics models are now ruled out…
(GeV)
A'
m
3 −
10
2 −
10
1 −
10 1 10 ε
4 −
10
3 −
10
2 −
10
e
(g-2) NA64 ν ν π → K σ 2 ±
µ
(g-2) favored
BABAR 2017
BABAR:1702.03327 Cosmic Visions 1707.04591
Conclusions based on first-generation measurements Motivates better understanding muon-philic interactions Weak scale models also under tension (e.g. MSSM)
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Best viable BSM explanation: new muon-philic particles How do we directly test this scenario?
γ µ µ
New particle couples to muons & decays invisibly
?
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TAGGING TRACKER
MAGNET ECAL HCAL
μ-
RECOIL TRACKER
E
/
20 CM
µ(E ⌧ 15 GeV)
µ(E ∼ 15 GeV)
Trigger missing energy Basic Setup: muon beam incident on fixed target
6E
V µ− µ− Z
Kahn, GK, Tran, Whitbeck 1803.XXXX Gninenko, Krasnikov, Matveev 1412.1400 Chen, Pospelov, Zhong 1701.07437
veto on all other SM particles
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Phase 1 ∼ 1010 MOT Phase 2 ∼ 1013 MOT
Generic test of light new particles in (g − 2)µ
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Overview & Motivation
1) Model independent test of g-2 anomaly 2) Probe models of muon-philic dark matter
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What is this stuff ?
Zeroth Order Outstanding Problems
Accelerated Expansion Cosmic Matter Asymmetry Also Quantum Gravity Inflation
2
Neutrino Masses
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Bad news: DM-SM interactions are not obligatory
If nature is unkind, we may never know the right scale
Good news: most discoverable DM candidates are in
thermal equilibrium with us in the early universe
Why is this good news?
DM Prognosis?
mDM
mP l
∼ 1019 GeV
∼ 100M
must be composite must be bosonic
∼ 100 eV
∼ 10−20 eV
DM Prognosis?
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Bad news: DM-SM interactions are not obligatory
If nature is unkind, we may never know the right scale
Good news: most discoverable DM candidates are in
thermal equilibrium with us in the early universe
Why is this good news?
DM Prognosis?
mDM
mP l
∼ 1019 GeV
∼ 100M
must be composite must be bosonic
∼ 100 eV
∼ 10−20 eV
DM Prognosis?
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H ∼ nσv = ⇒
If interaction rate exceeds
Leff = g2 Λ2 (¯ χγµχ)( ¯ fγµf)
Equilibrium is easily achieved in the early universe if
T 2 mP l ∼ g2T 5 Λ4
- T =mχ
g & 10−8 ✓ Λ 10 GeV ◆2 ✓GeV mχ ◆3/2
Hubble expansion Applies to nearly all discoverable models (except axions)
Thermal Equilibrium Advantage #0: Hard to avoid
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Thermal Equilibrium Advantage #1: Minimum Annihilation Rate
Griest et. al. 1992
Observed density requires
σvsym ∼ 3 × 10−26cm3s−1
Ωχ ⇠ hσvi−1
n(eq.)
DM =
Z d3p (2π)3 gi eE/T ± 1 ∼ T 3
DM is overproduced, need to annihilate away the excess!
Freeze out
*Known initial condition *Predictive rate *Insensitive to high scales
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Thermal Equilibrium Advantage #2: Narrows Mass Range
mDM
∼ 100M
∼ 10−20 eV
too hot too much < 10 keV > 100 TeV
GeV
mZ
MeV
nonthermal nonthermal
mP l ∼ 1019 GeV
“WIMPs”
Direct Detection (Alan Robinson) Indirect Detection (Alex Drlica-Wagner) Colliders (Yang Bai)
{
Light DM
{
18
````
< MeV
Thermal Equilibrium Advantage #2: Narrows Viable Mass Range
Neff / BBN
Most of current Search program
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Decades of direct detection: null results
1 10 100 1000 104 1050 1049 1048 1047 1046 1045 1044 1043 1042 1041 1040 1039 1014 1013 1012 1011 1010 109 108 107 106 105 104 103 WIMP Mass GeVc2 WIMPnucleon cross section cm2 WIMPnucleon cross section pb
7Be
Neutrinos
N EU T RIN O C O H ER E N T S CA T TE R ING N E UT R IN O C O H E RE N T S C A TTERIN G
(Green&ovals)&Asymmetric&DM&& (Violet&oval)&Magne7c&DM& (Blue&oval)&Extra&dimensions&& (Red&circle)&SUSY&MSSM& &&&&&MSSM:&Pure&Higgsino&& &&&&&MSSM:&A&funnel& &&&&&MSSM:&BinoEstop&coannihila7on& &&&&&MSSM:&BinoEsquark&coannihila7on& &
8B
Neutrinos A t m
- s
p h e r i c a n d D S N B N e u t r i n
- s
C D M S I I G e ( 2 9 ) X e n
- n
1 ( 2 1 2 )
CRESST CoGeNT (2012) CDMS Si (2013)
E D E L W E I S S ( 2 1 1 )
DAMA
SIMPLE (2012) ZEPLIN-III (2012) C O U P P ( 2 1 2 )
SuperCDMS Soudan Low Threshold XENON 10 S2 (2013) CDMS-II Ge Low Threshold (2011)
SuperCDMS Soudan Xenon1T L Z LUX DarkSide G2 DarkSide 50 DEAP3600 PICO250-CF3I P I C O 2 5
- C
3 F 8 S N O L A B S u p e r C D M S
Cushman et al. arXiv:1310.8327
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Null LHC results cast doubt on weak scale SUSY Where else should we look?
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Thermal Equilibrium Advantage #2: Narrows Mass Range
mDM
∼ 100M
∼ 10−20 eV
too hot too much < 10 keV > 100 TeV
GeV
mZ
MeV
nonthermal nonthermal
mP l ∼ 1019 GeV
“WIMPs”
Direct Detection (Alan Robinson) Indirect Detection (Alex Drlica-Wagner) Colliders (Yang Bai)
{
Light DM
{
18
````
< MeV
How to test most elusive light DM models?
Neff / BBN
Most of current Search program
?
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χ χ W, Z f f
Would be overproduced without light “mediators”
LDM must be a SM singlet
Otherwise would have been discovered (LEP etc.)
LDM needs new forces
σv ∼ α2m2
χ
m4
Z
∼ 10−29cm3s−1 ⇣ mχ GeV ⌘2
Lee/Weinberg ‘79
Light DM is different!
How do we look for new forces?
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S c a l a r R e l i c T a r g e t BaBar
MMAPS
Belle II LDMX
LSND
B D X
NA64 CRESST II
Super CDMS SNOLAB
E137
X E N O N 1 / 1
SENSEI NEWS
M i n i B
- N
E
SBNπ
S B N e SHiP
COHERENT
1 10 102 103 10-16 10-15 10-14 10-13 10-12 10-11 10-10 10-9 10-8 10-7 10-6
mχ [MeV] y = ϵ2αD (mχ/mA')4
Scalar Elastic DM (Kinetic Mixing)
Cosmic Visions Report 1707.04591
Emerging New Program of Light DM Experiments … but all probe electron & proton couplings!
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Major Blind Spot: Muon-Philic Dark “Mediators”
L ⊃ Z0
ν
- gµ¯
µγνµ + gχ ¯ χγνχ
- (mediator can be same Z’ responsible for g-2 anomaly)
χ
Z0
µ,τ µ,τ
µ
e.g. — gauged U(1) muon-tau number, no electron coupling
µ
χ
New force couple DM to muons, sets relic abundance
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TAGGING TRACKER
MAGNET ECAL HCAL
μ-
RECOIL TRACKER
E
/
20 CM
µ(E ⌧ 15 GeV)
µ(E ∼ 15 GeV)
Tests same interaction that sets relic abundance
A µ− χ ¯ χ µ−
Z0
Same setup as before: radiate missing energy
χ χ
Z0
µ,τ µ,τ
µ µ
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Cover nearly all predictive thermal DM models
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Including common g-2 regions
Cover nearly all predictive thermal DM models
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