Neutrino floor in EFT models

Jayden NewsteadArizona State University

collaborators:James Dent, Louis Strigari & Bhaskar Dutta

Coherent Neutrino Scattering Experiment Workshop 2015

Texas A&M

Introduction & take-away

● Coherent neutrino scattering is an irreducible background to direct dark matter detection experiments

● Complementarity and directional information can be used to mitigate its effect

● Non-standard interactions (not spin-independent/dependent) may provide a way to circumvent the neutrino 'floor'

Direct detection of WIMPs

11

time

photo

ns

E S1

Direct detection of WIMPs

11

time

photo

ns

E S1E

time

photo

ns

e-e-

S1

S2

time

photo

ns

S1 S2

Nuclear recoil

Electronic recoil

Background neutrino rate

Ruppin et al. 1408.3581

Both coherent nuclear elastic scattering →at worst practically indistinguishable

J. L. Newstead - 1505.03117 6

Non-relativistic EFT for DD

S⃗x

S⃗N

i q⃗v⃗

WIMP spinNucleon spin

Momentum transfervelocity

Spin independent

Spin dependent

J. L. Newstead - 1505.03117 7

Non-relativistic EFT for DD

Xenon-131, m = 50GeV, MB vel. dist.

EFT fits to neutrino rateFind best fit with a binned Poisson likelihood:

Fits to neutrino rateBoron-8 Atmospheric

Xe

Ge

Two regions of interest

Low region – solar neutrino background

High region – atmospheric neutrino background

low high

Neutrino rates in xenon:

Discovery evolution

Test statistic for discovery:

Include flux uncertainty in likelihood:

For a given exposure, find the cross section which produces a 3σ deviation from the null hypothesis 90% of the time

pn

Xenon-low O1 (SI):

Discovery evolutionGroup 2 and 3 operators only experience a weak saturation – no strong nu-floor

O1 O6 O10

low

high

pn

Discovery limits

For saturated exposure, find the cross section which produces a 3σ deviation from the null hypothesis 90% of the time

Test statistic for discovery:

O1 (SI):

Discovery limitsGroup 2 and 3 operators only experience a weak saturation – no strong nu-floor

O1 O6 O10

prot

onne

utro

n

Conclusion● Neutrino background is distinguishable from

non-standard WIMP interactions● If the WIMP interacts through a group 2 or 3

operator at leading order, the neutrino background will have a negligible effect on the discovery potential of WIMPs 'below the floor'

EFT fits to neutrino rate

Boron-8