@ University of Oxford 02/07/2019 · 2019. 2. 8. · Larger volume Theory: 1. The mediator is...
37
Searching for whispers from beyond the Standard Model Simon Knapen Institute for Advanced Study @ University of Oxford 02/07/2019
Transcript of @ University of Oxford 02/07/2019 · 2019. 2. 8. · Larger volume Theory: 1. The mediator is...
Searching for whispers from beyond the Standard Model
Simon KnapenInstitute for Advanced Study
@ University of Oxford02/07/2019
A once in a lifetime discovery…
ATLAS candidate higgs → 4μ event
15 million Higgs bosons produced in ATLAS + CMS so far
9 million decayed to b-quarks 3 x 104 decayed to photons 500 decayed to 4 muons
~ 1.5 million Higgs bosons could have decayed through an exotic channel
Top priority for the high-luminosity LHC
… but many mysteries remain
Hierarchy problem
Dark Matter
Baryon/anti-baryon asymmetry
The origin of flavor
CP violation
We need to expand our set of probes
ATLAS candidate higgs → 4μ event
A turning point4
Entering luminosity driven phase
Searches for “conventional” models already extremely sophisticated
LHC
Next generation experiments will push to the neutrino floor
(WIMP) dark matter direct detection
Searching for soft/subtle signatures by
• Using existing infrastructure in new ways ( “Leave no stone unturned” )
• Considering the next generation of experiments ( 5-10 years timescale )
This talk
Outline5
x
'
SM
SM
CODEX-b box
UXA shield
shield veto
IP8Pb shield
DELPHI
CODEX-b detector!
polar material detectorsuperfluid helium detector
Dark matter direct detectionLHC
Need a multidisciplinary approach
Three experimental proposals
The soft frontier at LHC
6
Long-lived particles are generic7
In the Standard Model Beyond the Standard Model
• Supersymmetry
• Dark matter
• Neutrino masses
• Baryogenesis
• …
Long-lived particles when there is a separation of scales and / or a weakly broken symmetry
M (GeV)
c⌧ (m)
10�10 10�3 1
10�20
10�10
1
1010
1040e
µ⌧ B±
⌥(4S)
tH
Z
J/
⇢
KL
KS
⌘⇡0
⇡±
n
p
⌫
102
Image by B. Shuve
Finding Long-Lived Particles
~ 10 nuclear interaction lengths
(ATLAS)
1. Tight trigger requirements 2. Backgrounds
… but for low masses they suffer from:
ATLAS and CMS are great for high mass LLPs…
Solution: Dedicated detector with ~ 3 times more shielding
8
A typical hadron has a chance of ~ 10-5 to punch through calorimeter…
…but the LHC makes ~ 109 KL mesons/s
LHCb cavern
x
DAQ
UXA shield IP8
DELPHI
LHCb
Data acquisition will be moved to surface for run 3
9
CODEX-b
x
'
SM
SM
CODEX-b box
UXA shield
shield veto
IP8Pb shield
DELPHI
With ~ 4 meters of shielding, background free
V. Gligorov, SK, M. Papucci, D. Robinson: 1708.0224310
x
'
µ+
µ�
CODEX-b box
UXA shield
shield veto
IP8Pb shield
DELPHICODEX-b
Possibly extra reach for muonic channels
V. Gligorov, SK, M. Papucci, D. Robinson: 1708.0224311
Backgrounds12
V. Gligorov, SK, M. Papucci, D. Robinson: 1708.02243
box rad. shield
µ veto
IP8Pb shield
• Absorb neutral hadrons in shield (irreducible background)
• Veto muon-induced backgrounds with muon veto + front face of the detector (reducible background)
Simulation: pythia 8 + GEANT 4 4.5m Pb + 3m concrete
BG species
Particle yields
Baseline Cuts
irreducible
by shield
veto
reducible by
shield veto
n+ n 7 5 · 104 Ekin > 1GeV
K0L 0.2 870 Ekin > 0.5GeV
⇡±+K±
0.5 3 · 104 Ekin > 0.5GeV
⌫ + ⌫ 0.5 2 · 106 E > 0.5GeV
Dominant background: neutron on air ~ 0.3 events
Higgs portal
b
W�
'
s
V. Gligorov, SK, M. Papucci, D. Robinson: 1708.02243
13
0.5 1.0 2.0 4.0
m' (GeV)
10�12
10�10
10�8
10�6
sin
2✓ 10 fb�1
CODEX-b
300 fb�1
NA62
SHiP
MATHUSLA
CHARM
LHCb, 3 fb�1
LHCb, 300 fb�1
Proposed 200 m x 200 m detector on the surface above CMS
Proposed ~ 150 m long beam dump at CERN SPS accelerator
Model: With � = 0<latexit sha1_base64="5YL8pMZuSXLiVQ7kmsJkW2qveno=">AAAB+XicbVC7SgNBFL3rM8bXqqXNYCJYhd002ghBG8sI5gHJEmZnZ5Mhsw9m7gbCkj+xsVDE1j+x82+cJFto4oGBwzn3cO8cP5VCo+N8WxubW9s7u6W98v7B4dGxfXLa1kmmGG+xRCaq61PNpYh5CwVK3k0Vp5Eveccf38/9zoQrLZL4Cacp9yI6jEUoGEUjDWy7I3BEqn1pIgG9daoDu+LUnAXIOnELUoECzYH91Q8SlkU8Riap1j3XSdHLqULBJJ+V+5nmKWVjOuQ9Q2Mace3li8tn5NIoAQkTZV6MZKH+TuQ00noa+WYyojjSq95c/M/rZRjeeLmI0wx5zJaLwkwSTMi8BhIIxRnKqSGUKWFuJWxEFWVoyiqbEtzVL6+Tdr3mOjX3sV5p3BV1lOAcLuAKXLiGBjxAE1rAYALP8ApvVm69WO/Wx3J0wyoyZ/AH1ucP1YSSdw==</latexit><latexit sha1_base64="5YL8pMZuSXLiVQ7kmsJkW2qveno=">AAAB+XicbVC7SgNBFL3rM8bXqqXNYCJYhd002ghBG8sI5gHJEmZnZ5Mhsw9m7gbCkj+xsVDE1j+x82+cJFto4oGBwzn3cO8cP5VCo+N8WxubW9s7u6W98v7B4dGxfXLa1kmmGG+xRCaq61PNpYh5CwVK3k0Vp5Eveccf38/9zoQrLZL4Cacp9yI6jEUoGEUjDWy7I3BEqn1pIgG9daoDu+LUnAXIOnELUoECzYH91Q8SlkU8Riap1j3XSdHLqULBJJ+V+5nmKWVjOuQ9Q2Mace3li8tn5NIoAQkTZV6MZKH+TuQ00noa+WYyojjSq95c/M/rZRjeeLmI0wx5zJaLwkwSTMi8BhIIxRnKqSGUKWFuJWxEFWVoyiqbEtzVL6+Tdr3mOjX3sV5p3BV1lOAcLuAKXLiGBjxAE1rAYALP8ApvVm69WO/Wx3J0wyoyZ/AH1ucP1YSSdw==</latexit><latexit sha1_base64="5YL8pMZuSXLiVQ7kmsJkW2qveno=">AAAB+XicbVC7SgNBFL3rM8bXqqXNYCJYhd002ghBG8sI5gHJEmZnZ5Mhsw9m7gbCkj+xsVDE1j+x82+cJFto4oGBwzn3cO8cP5VCo+N8WxubW9s7u6W98v7B4dGxfXLa1kmmGG+xRCaq61PNpYh5CwVK3k0Vp5Eveccf38/9zoQrLZL4Cacp9yI6jEUoGEUjDWy7I3BEqn1pIgG9daoDu+LUnAXIOnELUoECzYH91Q8SlkU8Riap1j3XSdHLqULBJJ+V+5nmKWVjOuQ9Q2Mace3li8tn5NIoAQkTZV6MZKH+TuQ00noa+WYyojjSq95c/M/rZRjeeLmI0wx5zJaLwkwSTMi8BhIIxRnKqSGUKWFuJWxEFWVoyiqbEtzVL6+Tdr3mOjX3sV5p3BV1lOAcLuAKXLiGBjxAE1rAYALP8ApvVm69WO/Wx3J0wyoyZ/AH1ucP1YSSdw==</latexit><latexit sha1_base64="5YL8pMZuSXLiVQ7kmsJkW2qveno=">AAAB+XicbVC7SgNBFL3rM8bXqqXNYCJYhd002ghBG8sI5gHJEmZnZ5Mhsw9m7gbCkj+xsVDE1j+x82+cJFto4oGBwzn3cO8cP5VCo+N8WxubW9s7u6W98v7B4dGxfXLa1kmmGG+xRCaq61PNpYh5CwVK3k0Vp5Eveccf38/9zoQrLZL4Cacp9yI6jEUoGEUjDWy7I3BEqn1pIgG9daoDu+LUnAXIOnELUoECzYH91Q8SlkU8Riap1j3XSdHLqULBJJ+V+5nmKWVjOuQ9Q2Mace3li8tn5NIoAQkTZV6MZKH+TuQ00noa+WYyojjSq95c/M/rZRjeeLmI0wx5zJaLwkwSTMi8BhIIxRnKqSGUKWFuJWxEFWVoyiqbEtzVL6+Tdr3mOjX3sV5p3BV1lOAcLuAKXLiGBjxAE1rAYALP8ApvVm69WO/Wx3J0wyoyZ/AH1ucP1YSSdw==</latexit>
L � µ'H†H +�
2'2H†H
Exotic Higgs decays
For low masses, ATLAS/CMS are background limited, CODEX-b has an edge
ATLAS reach rescaled from: 1811.07370
�d
�d
h
V. Gligorov, SK, M. Papucci, D. Robinson: 1708.02243
14
Moving forward15
We are part of the “Physics Beyond Colliders” effort at CERN(See 1901.09966 for many more signal benchmarks)
• Background data analysis• Detector design and simulation• 1th collaboration meeting in June 2019 at CERN
Ongoing work on the LHCb sideMuon tagger in UX85A cavern
On track for a full proposal by late 2019
2018 2020 2023 2027
Run 2 LS2 Run 3 LS3 HL-LHC
BG study & design
Mini install? Background measurements
CODEX-binstall
CODEX-brun
A more ambitious version16
V. Gligorov, SK, B. Nachman, M. Papucci, D. Robinson: 1810.03636
5.5 m
14 m
4.25 m
IPBeamline
L3 Solenoid
IP
D4
D3D1D2
Detector
Approx. to scale
“AL3X” in the ALICE cavern
• Reuse L3 magnet and ALICE TPC (excellent momentum measurement!)
• Comparable reach to MATHUSLA and SHiP combined
• Contingent upon:- ALICE physics program in run 5- Modification of the beam line (~ 100 fb-1 needed)
b
W�
'
s
0.5 1.0 2.0 4.0
m' (GeV)
10�14
10�12
10�10
10�8
10�6
sin
2✓
CHARM
LHCb
Full detector
AL3X : 100 fb�1
AL3X : 250 fb�1
CODEX-b
SHiP
MATHUSLA100
Soft signatures with existing detectors17
Tracking for QuirksSK, H. Lou, M. Papucci, J. Setford: 1708.02243
ALPs in heavy ion collisionsSK, T. Lin, H. Lou, T. Melia: 1607.06083 ,1709.07110
CMS collaboration: 1810.04602
SK, et. al. : 1612.00850with ATLAS collaboration: in progress
CMS vertex triggerY. Gershtein, SK: in progress
J. Shelton, SK, D. Xu: in progress
Triggers for dark showers
The soft frontier in dark matter detection
18
Freeze-out, Freeze-in, Asymmetric, SIMP, …
meV eV keV MeV GeV 109 GeVTeV10-22 eV
Models of Dark Matter19
Light bosonic Dark Matter WIMP Composite
Dark Matter
! !
SM SM
meV eV keV MeV GeV
dark photon
Freeze-in
Freeze-outStellar cooling limits BBN limit
Freeze-out: Freeze-in:
Dark Matter drops out of equilibrium with Standard Model (e.g. WIMP’s)Dark Matter is never in equilibrium; Standard Model “leaks” into the dark sector
Dark matter direct detection
Cosmic visions report 2017: 1707.04591
Lower thresholds
Larger volumeTheory:
1. The mediator is important, independent set of constraints SK, T. Lin, K. Zurek: 1709.07882
2. Beyond “billiard ball” scattering: structure effects are critical!
Experiment:1. Low target mass materials:
2. Ultra-sensitive calorimeters with low dark counts
What do we need?
q < 2m�v�, v� ⇡ 10�3
ER =q2
2mN< 10�6 ⇥
m2�
mN
20
• 1 MeV < m! < 1 GeV → electron recoils
Structure effects
Attempt to “match” target mass with dark matter mass
• m! > 1 GeV → nuclear recoils
• m! < 1 MeV → q ≈ m! v! < keV ~ nm-1
• 1 MeV < m! < 1 GeV → electron recoils
Structure effects
Attempt to “match” target mass with dark matter mass
Scatter of collective excitations(e.g. phonons)
• m! > 1 GeV → nuclear recoils
• m! < 1 MeV → q ≈ m! v! < keV ~ nm-1
Proposed Detectors23
Superfluid helium detector Polar material detector
SK, T. Lin, M. Pyle, K. Zurek: 1712.06598S. Griffin, SK, T. Lin, M. Pyle, K. Zurek: 1807.10291
Detector concept: W. Guo, D. McKinsey: 1302.0534 SK, T. Lin, K. Zurek: 1611.06228
!
Scalar mediator only Scalar mediator &dark photon mediator
0 1 2 3 4 5 6
q [keV]
0
1
2
3
4
5
✏[m
eV]
phon
on roton
Bijl-Feynman
Measured
Quadratic
0.5 1.0 1.5 2.0 2.5 3.0q [1/A]
0
10
20
30
40
50
✏[K
]
Issue: speed of Dark Matter >> speed of sound
Cannot scatter against single, on shell excitation
Phonons & rotons in superfluid He
SK, T. Lin, K. Zurek: 1611.06228
24
He
pi pf
(k2,!2)
(k1,!1)
(q,!)
Final state: two hard, back-to-back phonons
Calculate the 3-excitation matrix elementR. Feynman, 1954H. W. Jackson, E. Feenberg, 1962E. Feenberg, 1969M. J. Stephen, 1969
25
Comparison with simulation
10�3 10�2 10�1 1 10 102
mX [MeV]
10�44
10�43
10�42
10�41
10�40
10�39
10�38
10�37
10�36
10�35
�p
[cm
2 ]
Nuclear recoil
↵X = 10�11 (mX/MeV)3/2, gn = 10�11
↵X = 10�11 (mX/MeV)3/2, gn = 10�10
Massless mediator
Leading order
CKL15
kg x year exposure no background
Reach agrees within a factor of ~ 2 with extrapolated simulation data*
* Campbell, Krotscheck and Lichtenegger (2015) SK, T. Lin, K. Zurek: 1611.06228
26
Reach
Superfluid helium can be sensitive down to m! ~ 10 keV
Cosmic visions report 2017: 1707.04591
Polar Materials27
At least two different atoms in the unit cell
GaAs Al2O3 (Sapphire)
2 atoms in primitive cell 10 atoms in primitive cell
Primary crystal axis
Why polar materials?28
3. Semi-conductors or insulators: screening is small
4. Crystal axis allows for directional detection (daily modulation!)
5. Readily available now
1. Optical phonons for kinematic matching
� X W � L0
5
10
15
20
25
30
35
40
!(m
eV)
LO
TO
TA
LA
GaAs
2. Natural dipole in unit cell (milicharged DM sources tiny electric field)
E
Ga As
Optical phonon
SK, T. Lin, M. Pyle, K. Zurek: 1712.06598
GaAs Brillouin zone
Frölich Hamiltonian29
S. Griffin, SK, T. Lin, M. Pyle, K. Zurek: 1807.10291
Electric dipole interacting with test charge:
VASP phonopyCrystal structure
Phonon energies & eigenvectors
DFT calculation diagonalize force matrix
Force constantsBorn effective charges
Calculation overview:
Sum over:• j atoms in unit cell• " phonon modes• q 1st Brillouin zone• G reciprocal lattice
phonon energy
Born effective charge tensor for each atom
phonon eigenvectors(atomic displacements)
high frequency dielectric tensor
H. Frölich, 1954C. Verdi, F. Giustino, Phys. Rev. Lett. 115, 176401 (2015)
10�3 10�2 10�1 100 101 102 103
m� [MeV]
10�4510�4410�4310�4210�4110�4010�3910�3810�3710�3610�3510�3410�3310�32
�e
[cm
2 ]
CM
B
BBNStellar bounds
Freeze-in
SuperCDMS G2DAMIC-1K
LBECA
SENSEI-100g
ZrTe5
Al SC
Xenon10
Dark photon mediatormA0 ⌧ keV
GaAsAl2O3
Al2O3 (mod)
phono
n
scintillat
or
Reach30
SK, T. Lin, M. Pyle, K. Zurek: 1712.06598S. Griffin, SK, T. Lin, M. Pyle, K. Zurek: 1807.10291
Both GaAs and Sapphire probe Dark Matter masses as low as 10 keV(“milicharged” dark matter)
Probe the new parameter space with milligram-day exposure
kg-year exposure, no background
Al2O3 Brillouin zone
Most important mode31
S. Griffin, SK, T. Lin, M. Pyle, K. Zurek: 1807.10291
Most energetic mode dominates
� L B1 B Z � X Q F P1 Z L P0
20
40
60
80
100
120
!(m
eV)
Al2O3
Aluminum atoms move in phase
Large dipole
Daily modulation32
Daily modulation depends on dark matter mass, type of mediator type and threshold
Potential to measure the dark matter mass and mediator type using the daily modulation!
0.0 0.2 0.4 0.6 0.8 1.0
t/day
0.7
0.8
0.9
1.0
1.1
1.2
1.3
R/h
Ri
A0 mediatormX=25 keV
mX=50 keV
mX=75 keV
mX=100 keV
S. Griffin, SK, T. Lin, M. Pyle, K. Zurek: 1807.10291
0.0 0.2 0.4 0.6 0.8 1.0
t/day
0.6
0.8
1.0
1.2
1.4
R/h
Ri
mX=50 keV � mediator
! > 1 meV
! > 25 meV
! > 50 meV
! > 75 meV
Dark photon absorption33
Dark photon dark matter:
Extracted from the measured index of refraction
10�3 10�2 10�1 100 101 102
mA0 [eV]
10�18
10�16
10�14
10�12
10�10
Stellarconstraints
Al SC
e�
excitation
Ge
phononexcitation
Si
Dirac materialM
olecules
Direct detectionconstraints
1 kg-yr, Sapphire
1 kg-yr, GaAs
S. Griffin, SK, T. Lin, M. Pyle, K. Zurek: 1807.10291 (for a model see e.g. A. Long, L. Wang: 1901.03312)
Looking ahead34
Theory:• Extend the calculation beyond first Brillouin zone (heavier dark matter, neutrinos)• Multi-phonon production (similar to superfluid He)• Generalize to different materials (e.g. PbS, SiC, …)
Experiment:• 100 #m x 400 #m TES with 50 meV resolution achieve by Matt Pyle’s group in
Berkeley• Next steps:
• Scale & cool down TES further → 1 meV resolution• Build and optimize collector interface• Fabricate sensor on crystal (Si and GaAs first, sapphire later)
Dark Matter Summary35
meV eV keV MeV GeV
dark photon
Freeze-in
Freeze-out
109 GeV
composite dark matter*
* A. Coskuner, D. Grabowska, SK, K. Zurek: 1812.07573
!Superfluid Helium
scalar mediator scalar mediator
Polar materials
dark photon & scalar mediators
dark photon & scalar mediators
dark photon absorption
Conclusion36
The LHC will run for another ~ 15 years• Higgs couplings / exotic decays• Searches for new physics
No free lunch: diminishing returns unless we keep innovating!
The search for cracks in the Standard Model is also diversifying rapidly
SK + few hundred others
New (renewed) attention for:
light dark matteraxion-like dark matter
gravitational wave detectors
“smaller” accelerators experiments (Seaquest, NA62, COMPASS, Belle II …)
(neutron) stars
neutrino experiments….
Crucial input from• Nuclear physics• Condensed matter physics• Astrophysics / cosmology
Particle physics is evolving to a more multidisciplinary field
Dark matter summary37
Thank you!
