Searching for Signatures of Fundamental Physics in the CMB. Raphael Flauger

Transcription

1 Searching for Signatures of Fundamental Physics in the CMB Raphael Flauger StringPheno, Blacksburg, VA, July 5, 2017

2 Introduction Cosmological observations can reveal important information about fundamental physics The detection of primordial gravitational waves in the CMB would teach us about the expansion rate and energy scale of inflation V 1/4 inf H inf = GeV during r 1/ that the inflaton traversed a Planckian field range

3 Field Range Super-Planckian displacements are not expected in a generic low energy effective field theory Possible Solution: Invoke a shift symmetry and break the shift symmetry in a controlled way. e.g. Linde s chaotic inflation natural inflation V (φ) = 1 2 m2 φ 2 V (φ) =Λ 4 1 cos φ f with with m M p f M p

4 Field Range We may postulate such a symmetry in field theory, but it is not obvious that such shift symmetries exist in a theory of quantum gravity. Does string theory admit super-planckian excursions? Many interesting talks Blumenhagen, Hebecker, Heidenreich, Kläwer, McAllister, Rudelius, Shiu, Stout, Valenzuela, Wolf

5 Axion Monodromy Inflation One mechanism that seems to allow super-planckian excursions with sub-planckian f is monodromy VΦMp ΦM p

6 Axion Monodromy Inflation Monodromy is generic in the presence of branes and fluxes Stabilizing moduli at high enough scales and controlling all moving parts is challenging.

7 Axion Monodromy Inflation Monodromy is generic in the presence of branes and fluxes Stabilizing moduli at high enough scales and controlling all moving parts is challenging. Comic version of axion monodromy inflation NS5 5B C (2) = c anti 5B anti-ns5

8 Axion Monodromy Inflation The tension backreacts In addition, for the NS5 brane there is S CS C 2 C 4 so that displacement of the inflaton induces 3-brane charge N w = φ 2πf This sources 5-form flux that backreacts on the geometry

9 Axion Monodromy Inflation In any model of monodromy some flux must keep track of the branch. This flux carries energy density and backreacts on the geometry. The scale associated with this effect is f M p In the NS5 model significant work is needed to delay large backreaction until. 2πN c f>m p

10 Axion Monodromy Inflation There is interesting phenomenology associated with the scale f ED1 5B NS5 C (2) = c anti 5B anti-ns5 Instanton corrections may lead to oscillatory contributions to the potential. V (φ) =µ 3 φ + Λ 4 cos φ f These lead to oscillations in the power spectrum that can be searched for.

11 Axion Monodromy Inflation In general the decay constant and amplitude may themselves depend on the inflaton V (φ) =µ 4 p φ p + Λ(φ) 4 1+pf φ cos 0 φ f 0 φ 0 + ϕ This leads to a power spectrum of the form 2 R (k) = 2 R ns 1 k φ k 1+δn s cos 0 f φk φ 0 pf +1 + ϕ δn s =3b 2π α 1/2 with α =(1+p f ) φ 2pN0 1+pf 0 2fN 0 φ 0 arxiv:

12 Axion Monodromy Inflation Search for oscillations with drifting period in Planck nominal mission data and full mission data

13 Axion Monodromy Inflation Improvement of the fit over CDM: Expectation based on simulations in the absence of a signal: χ 2 = 16.5 ± 3.5 Λ χ 2 = 18 As of now there is no evidence for such oscillations in the primordial power spectrum. One should keep in mind that there are additional mechanisms that lead to periodic signatures that have not yet been searched for.

14 Axion Monodromy Inflation Monodromy in the spectrum m 2 n µ 2 + g 2 (φ φ n ) m Leads to periodic bursts of particle/string production, which source perturbations in the inflaton large enough to be detectable even if the states are never light µ φ 1 2. φ arxiv:

15 Axion Monodromy Inflation The resulting bispectrum for particle production can be computed ΩH2 ΩH S2 ak,k,k S2 ak,k,k kmpc kmpc 1 and is orthogonal with existing shapes for a range of frequencies.

16 Axion Monodromy Inflation Modulated moduli masses Moduli dependence of the potential V (φ, χ) =µ 3 φ + Λ 4 (χ) cos leads to modulated masses for moduli m 2 µ 2 + g 2 f 2 cos Again leads to periodic bursts of particle production, which source perturbations in the inflaton large enough to be detectable even if the states are never light µ φ 1 2. φ f φ f + V (χ)

17 Axion Monodromy Inflation The resulting bispectrum ΩH2 ΩH S2 bk,k,k S2 bk,k,k kmpc kmpc 1 is orthogonal to existing shapes over a wide range of frequencies

18 Current Experiments Stage III: now-2020 POLARBEAR/ Simons Array SPTPol/SPT3G SPIDER BICEP/Keck EBEX ABS ACTPol/ AdvACT CLASS

19 Stage III.5: soon-2020 Future Experiments

20 Stage IV: Future Experiments Potentially Space Missions LiteBIRD, PIXIE

21 CMB-S4 Joint effort of entire US CMB community September 2015 Collaboration Workshop University of Michigan March 2016 Collaboration Workshop LBNL September 2016 Collaboration Workshop University of Chicago CMB-S4 Science Book ( March 2017 Collaboration Workshop SLAC

22 CMB-S4 The science goals most relevant to the high energy community are Detect primordial gravitational waves or place an upper limit r<0.001 at 95%CL Measure N eff with a precision of σ(n eff ) 0.03 Determine the sum of neutrino masses at even for the minimum value allowed for the normal hierarchy (58 mev) 2σ

23 CMB-S4 CMB-S4 will be a single experiment and collaboration at two sites (South pole and Atacama) deep survey on small patch for primordial B-mode search wide survey for measurement of effective number of relativistic degrees of freedom, neutrino mass, growth of structure,...

24 Primordial B-modes Seemingly straightforward because at linear order scalar perturbations do not generate B-modes. However, weak gravitational lensing of the CMB by intervening matter converts E- to B-modes Galactic foregrounds generate B-modes

25 Primordial B-modes The challenge is to use maps with auto-spectra shown below to tell the difference between (r=0)... 1C2ΠΜ K GHz 40 GHz 155 GHz 270 GHz 220 GHz 145 GHz 95 GHz 85 GHz

26 Primordial B-modes and (r=0.003)... 1C2ΠΜ K GHz 40 GHz 155 GHz 270 GHz 220 GHz 145 GHz 95 GHz 85 GHz at 5σ

27 Primordial B-modes Lensing B-modes can be partially removed through precise measurements of the lensing potential and E-modes 10 1C2ΠΜ K GHz 40 GHz 155 GHz 270 GHz 220 GHz 145 GHz 95 GHz 85 GHz lensing/

28 Primordial B-modes r= C2ΠΜ K GHz 40 GHz 155 GHz 270 GHz 220 GHz 145 GHz 95 GHz 85 GHz lensing/

29 Primordial B-modes Foreground cleaned spectrum and foreground residuals from simulation 1C2ΠΜ K CMB+FG residuals dust residuals synchrotron residuals 10 6 AME residuals

30 Primordial B-modes CMB-S4 would detect r=0.01 at high significance CMB-S4 Science Book ( r M=10 M P M=12 M P M=2 M P M=20 M P n s BK14/Planck 4 V (1- (φ/m) ) CMB-S4 0 V tanh (φ/m) m φ 47< N μ 3 * < 57 φ 47< N * < 57 10/3 2/3 μ φ 47< N < 57 Higgs R 2 2 * N * = 57 N = 50 *

31 Primordial B-modes Even an upper limit from CMB-S4 is interesting If the inflationary model naturally explains the observed value of the spectral index, i.e. n s (N ) 1= p +1 N then the inflationary part of the potential is either V (φ) =µ 4 2p φ 2p or V (φ) =V 0 exp 2p φ p 1 Λ (p = 1) The characteristic scale in latter case is M = Λ 1 p p

32 Primordial B-modes r CMB-S4 Science Book ( CMB-S4 BK14/Planck φ p 47< N < An upper limit with CMB-S4 would disfavor all models of inflation that naturally explain n s with super-planckian characteristic scale M n s M = 5M P N = 57 * M = 2M P N * = 57 M = 1M P N = 57 * M = M P/2 N = 57 * Higgs N * = 57 R 2 N * = 50 *

33 Light Relics Light Relic Particle that is stable on cosmological time scales and light enough to be relativistic at recombination Contribute to the energy density in radiation ρ rad = π2 kb c /3 4 N eff 8 11 T 4 γ with N eff =3.046 in the Standard Model With σ(n eff ) 0.03, CMB-S4 will place interesting constraints on many extensions of the standard model

34 Conclusions Cosmological observations allow us to test our ideas about the early universe Many experiments are already taking data, many will soon come online and will constrain light relics, neutrinos, dark matter,... The next decade will be eventful and we should continue to learn a lot about the early universe and particle physics from CMB (as well as other cosmological) experiments It would be great to understand what string theory predicts for these experiments before then

35 Thank you