Cosmic Axion Detection with an Amplifying B-field Ring Apparatus Ben Safdi Massachusetts ...

62 Pages·2016·11.32 MB·English

Cosmic Axion Detection with an
Amplifying B-field Ring Apparatus
Ben Safdi
Massachusetts Institute of Technology
2015
Dark-matter is opportunity to learn about BSM
Axions WIMPS
-12 -3 9 12
log (m /eV)
10 a
Clear evidence that dark-matter (BSM physics) exists
•
Well motivated dark-matter models (WIMPs, axions, ...)
•
How can we probe axion dark matter?
Astrophysics Axion helioscope Resonant cavity
BH superradiance CAST
Figure1:AxionicBlackHoleAtom:Thespinningblackhole“feeds”superradiantstatesform-
inganaxionBose-Einsteincondensate.Theresultingbosonicatomwillemitgravitonsthrough
axiontransitionsbetweenlevelsandannihilationsandwillemitaxionsasaconsequenceofself-
interactionsintheaxionfield.
ADMX
Consequently,onemayexpecthundredsofaxion-likeparticlesinagivenstringcompactification.
However,aplenitudeofcyclesdoesnotyetguaranteethepresenceofaplenitudeofaxions.There
iwsraapnpuinmgbtehreocfyec↵leeAsc,tsansindtflsturrxinoegs.tpOhenoherycyatnhasrtoucigochullydseps/rtoicmduaocteetashelamnrguemaboxeirolnoofmligagshst,yasxu:icohnsassastbbreaeninelgslar cooling, CMB, BBN (Phys.Lett.
determinedby•thenumberofcycleswithoutfluxes—presumably,aroundonetenthofthetotal
numberofcyclBes..S2till0th1is4lea:veKsu.swBithluthmeex,peRcta.tioDno’fAsegvernalotelnoso,fMaxi.onL-likiespaarntictleis,.B.S.), superradiance
Thediscoveryofaplenitudeofparticlesinourvacuumwithsimilarpropertiesbutdi↵erent
mdyansasemsicsaulpcpoonrstesqtuheLenciedaseaobfotfhoaesparlmeaneitfuutdnoedaomrfevynatcaulaei,nagxsrebdpoietnhetst.hreiaxmiverseeanndtthse:mulAtiverDseaMre X (resonant cavity), CAST
Themasses•ofstringaxionsareexponentiallysensitivetothesizesofthecorrespondingcycles,
sooneexpects(tahemxtoiobenhomohgeneeoulsilyodisstricbuotedponethe)l,oga.rith.m.icscale.However,given
thattheQCD✓-parameterisconstrainedtobelessthan10�10,non-perturbativestringcorrections
totheQCDaxionpotentialshouldbeatleasttenordersofmagnitudesuppressedascompared
totheQCDgeneraNtedepotwentialp. Itriosthpenonasturaaltlo:exp1ect6m0any2of.th0ea1xio0ns8to6bem(ucYh.Kahn, B.S., J.Thaler): A
lnigohnTt-pehreertthiumarnbpalittchib•ivete,QasrtnCrodDinvgaaexery↵iodenpc;ltasbtu.hseibsaeleanaresstudhmepatxaioionnpbsewhphinodrsetohmisaaslsinicesodhfomreianstaotoneidngonaislytxhbaytittohheesrneesimsandlolark matter detection
anthropicreasonfortheexistenceandpropertiesoftheQCDaxion.Consequently,theseproperties ADMX
shouldfollowfromthedynamicsofthecompactificationmanifold,ratherthanbeingaresultof
fine-tuning,andtheQCDaxionshouldbeatypicalrepresentativeamongotheraxion-likefields.
Aprioriweexpecttens(orevenhundreds)oflightaxions,itwouldbereallysurprisingifthe
QCDaxionturnedouttobethesingleone.
5
Outline
(cid:73) Axion particle physics (review)
(cid:73) Axion cosmology (review)
(cid:73) ABRACADABRA: Cosmic axion detection (theory)
(cid:73) ABRACADABRA-10 cm at MIT (experiment)
Why axions and what are they?
(cid:73) Calculation: d 2.4 10 16θ¯ e cm
n −
≈ × ·
(cid:73) Measurement: θ¯ < 10 10
−
| |
(cid:73) No anthropic argument for why θ¯is so small!
The axion solves the strong CP problem
θg2
= G G˜µν q¯m e iφqγ5q
LCQPCD −32π2 µν − q −
q
(cid:88)
(cid:73) U(1) anomaly: q e iαqγ5q
A −
→
θ θ+2 α
q
→
q
(cid:88)
(cid:73) U(1) invariant: θ¯ θ φ
A q
≡ −
q
(cid:88)
Peccei,Quinn1977;Weinberg1978;Wilczek1978
(cid:73) Measurement: θ¯ < 10 10
−
| |
(cid:73) No anthropic argument for why θ¯is so small!
The axion solves the strong CP problem
θg2
= G G˜µν q¯m e iφqγ5q
LCQPCD −32π2 µν − q −
q
(cid:88)
(cid:73) U(1) anomaly: q e iαqγ5q
A −
→
θ θ+2 α
q
→
q
(cid:88)
(cid:73) U(1) invariant: θ¯ θ φ
A q
≡ −
q
(cid:88)
(cid:73) Calculation: d 2.4 10 16θ¯ e cm
n −
≈ × ·
Peccei,Quinn1977;Weinberg1978;Wilczek1978
The axion solves the strong CP problem
θg2
= G G˜µν q¯m e iφqγ5q
LCQPCD −32π2 µν − q −
q
(cid:88)
(cid:73) U(1) anomaly: q e iαqγ5q
A −
→
θ θ+2 α
q
→
q
(cid:88)
(cid:73) U(1) invariant: θ¯ θ φ
A q
≡ −
q
(cid:88)
(cid:73) Calculation: d 2.4 10 16θ¯ e cm
n −
≈ × ·
(cid:73) Measurement: θ¯ < 10 10
−
| |
(cid:73) No anthropic argument for why θ¯is so small!
Peccei,Quinn1977;Weinberg1978;Wilczek1978
(cid:73) Axions also couple to QED:
1 α
= g aF F˜µν g EM
aγγ µν aγγ
L −4 ∝ f
a
The axion solves the strong CP problem
a g2
= θ¯+ G G˜µν
Laxion − f 32π2 µν
(cid:18) a(cid:19)
(cid:73) QCD generates axion mass:
2
1 a
V(a) f2m 2 θ¯+
≈ 2 a a f
(cid:18) a(cid:19)
f 1016 GeV
m πm 10 9 eV
a π −
≈ f ≈ f
a (cid:18) a (cid:19)
Peccei,Quinn1977;Weinberg1978;Wilczek1978
The axion solves the strong CP problem
a g2
= θ¯+ G G˜µν
Laxion − f 32π2 µν
(cid:18) a(cid:19)
(cid:73) QCD generates axion mass:
2
1 a
V(a) f2m 2 θ¯+
≈ 2 a a f
(cid:18) a(cid:19)
f 1016 GeV
m πm 10 9 eV
a π −
≈ f ≈ f
a (cid:18) a (cid:19)
(cid:73) Axions also couple to QED:
1 α
= g aF F˜µν g EM
aγγ µν aγγ
L −4 ∝ f
a
Peccei,Quinn1977;Weinberg1978;Wilczek1978