New Searches for Subgravitational Forces

Transcription

1 New Searches for Subgravitational Forces Jay Wacker SLAC University of California, Davis November 26, 2007 with Peter Graham Mark Kasevich 1

2 New Era in Fundamental Physics Energy Frontier LHC Nature of Electroweak Symmetry Breaking (Higgs, Naturalness, New Symmetries/Dimensions) 2

3 New Era in Fundamental Physics Energy Frontier LHC Nature of Electroweak Symmetry Breaking (Higgs, Naturalness, New Symmetries/Dimensions) Precision Frontier Atom Interferometry Strong CP Solution, Nature of CC/DM (Axions, Naturalness, New Forces, Violations of GR) Rapidly advancing - Gaining 10 in sensitivity per year 2

4 Atomic Interferometer 10 m 10 m atom drop tower. currently under construction at Stanford 3

5 Outline Motivation for New Forces Atom Interferometry Fifth Force Experiments Deviations in Newtonian Gravity Equivalence Principle Violating Forces Outlook 4

6 One Precision Frontier: Short Distance Gravity Many suggestions for fifth forces α 1 2 m p M Pl φ λ = m φ c p p Parameterization of new force δv (r) = α G NMm α λ r exp( r/λ) Strength relative to gravity Range (i.e. Compton wavelength) G N 1 M 2 Pl 5

7 Moduli Mediated Forces In Supersymmetry some particles only get mass from supersymmetry breaking If m φ m2 susy M Pl m susy 1 TeV = λ = m φ c 1 mm Generically have gravitational size couplings to matter L int = α 1 2 p m p M Pl φ pp φ p 6

8 Large Extra Dimensions M P lanck V (r) 1 r Ln r n+1 EM+ QCD Strength Gravity M W eak E 1 r 7

9 Large Extra Dimensions V (r) 1 r Ln r n+1 EM+ QCD Strength α Gravity M P lanck M W eak M Weak E 1 r M Planck 7

10 Basic Idea All forces start out equal at weak scale EM & QCD live in 4 dimensions, gravity lives in more and dilutes High scale physics is just a mirage 3-d brane Gravity is different at a new scale: mm to fm 8

11 Composite Gravity The Cosmological Constant Λ CC = Λ CC c (50 µm) 4 c ɛ 4 9

12 Composite Gravity The Cosmological Constant Λ CC = Λ CC L c (50 µm) 4 c ɛ 4 Cosmological expansion driven by coupling to gravity h µν Λ CC c L 4 9

13 Composite Gravity The Cosmological Constant Λ CC = Λ CC c (50 µm) 4 c ɛ 4 Cosmological expansion driven by coupling to gravity h µν If the graviton is composite with a size 50µm no coupling to small loops L Λ CC c L 4 L<ɛ 9

14 Composite Gravity The Cosmological Constant Λ CC c (50 µm) 4 Λ CC = c ɛ 4 Cosmological expansion driven by coupling to gravity h µν L Λ CC c L 4 If the graviton is composite with a size 50µm no coupling to small loops L<ɛ No known theory does this Motivates looking at short distance gravity 9

15 Neutrinos in the Standard Model mediate a very tiny, unscreenable force e e W e ν ν W e V ν G2 e F mνc r/ 16π 2 r 5 m ν c 1 mm V N (r 100µm) Still futuristic, but something to aim for! 10

16 Short Distance Gravity Experiments D.J. Kapner, et.al.,hep-ph/

17 Outline Motivation for New Forces Atom Interferometry Fifth Force Experiments Deviations in Newtonian Gravity Equivalence Principle Violating Forces Outlook 12

18 Space-time Interferometry ct Mirrors v 2 Output Ports v 1 v 1 v 2 Mach-Zehnder Inteferometer Beam-Splitters 10m Stanford Inteferometer Kasevich & Hogan x 1 m cτ = 10 8 m A AI 10 8 m 2 A Ligo 10 7 m 2 x Time is a big lever-arm in area 13

19 Fine Split 1 ev Raman Transitions Two photon transition E 2p Hyperfine Split 10 5 ev ω 2 ω emitted 2 2 ω 1 1s ω 1 absorbed p 1 ev E 0 1 p 14

20 i d dt ( ) 1 2 Rabi Oscillations Effectively 2 state oscillations = ( 0 Ω Rabi /2 Ω Rabi /2 0 ) ( ) 1 2 c 1 2, c beamsplitter mirror 1 Ψ ,p 2,p k Π Π 3 Π π/2 π 2 3π/2 2 2 Ψ 2 Ω Rabi t 2 Π t Rabi 1 15

21 Atom Interferometry t O 1 = 1 (1 + cos φ) 2 O 2 = 1 (1 cos φ) 2 t = 2T t = T π 2 π pulse pulse t = 0 π 2 pulse mirrors and beamsplitters are lasers x 16

22 Difference of Phases Φ =[V (0) V (v r T )] T ct O 1 O 2 V (x) x 17

23 Slowly changing potentials For optical transitions and Rb x = v r T 1 mm ct V (x) = V 0 + V x(t) + V x 2 (t) φ = V T V V x V (x) x φ F v r T T Force Area Interferometers are accelerometers for V x / V 1 18

24 Quickly changing potentials Consider Yukawa potential ct V (x) = V 0 exp( x/λ) For x λ measures potential differences Φ V 0 T V 0 m a λ V (x) x Insensitive to momentum imparted 19

25 Outline Motivation for New Forces Atom Interferometry Fifth Force Experiments Deviations in Newtonian Gravity Equivalence Principle Violating Forces Outlook 20

26 The Gyroscope Configuration Launch vertically but shine lasers horizontally Measures the force in laser s direction Free motion in horizontal direction Ballistic motion - time and height the same z P h = gt 2 z I x 21

27 Experimental Set-up First measure null z P z I Φ Null 22

28 Experimental Set-up Lasers shine horizontally towards test mass Move test mass in and out and measure its gravity z P L z I w x N Φ Near Φ Null 22

29 Experimental Set-up Lasers shine horizontally towards test mass Move test mass in and out and measure its gravity z P L z I w x F Φ Far Φ Near Φ Null 22

30 λ 500 nm Precision Φ = kat 2 = h a λ g Dimensions of experiment a G N ρw 10 8 g h 10 cm Signal Size Φ 10 2 Resolution δφ

31 λ 500 nm Precision Φ = kat 2 = h a λ g Dimensions of experiment a G N ρw 10 8 g h 10 cm Signal Size Φ 10 2 Resolution δφ 10 1 N atoms 10 6 N bunches 10 6 Ultimate Resolution 1 δφ Nb N a Φ

32 Measurement Strategy G N unknown = Normalization of V (x) unknown Must measure at two distances V 0 + ax x L log V (x) x 2 log x L 24

33 Measurement Strategy G N unknown = Normalization of V (x) unknown Must measure at two distances λ < L λ > L log V (x) log x L 24

34 Measurement Strategy G N unknown = Normalization of V (x) unknown Must measure at two distances x N x F log V (x) log x L 24

35 Measurement Strategy G N unknown = Normalization of V (x) unknown Must measure at two distances x N x F log V (x) log x L 24

36 Limits on Resolution Newtonian Prediction Atoms initially held in laser trap Wide wave packet x 100 µm V(x) x 25

37 Limits on Resolution Newtonian Prediction Limits on source mass geometry V m a x (1 + O(x/L)) Planar Geometry Uncertainty in the position looks like new force Systematic δv/v 10 6 Stochastic δv Nb V 10 9 δx 1 µm V(x) x 26

38 Casimir / van der Waal s Force V (r) = α 0 r 4 α 0 polarizability 20 Å 3 Put in shield to keep environment constant 30 µm shield bends by 1 nm Near Far z P z P L L z I z I w x d w x d 27

39 Coriolis Force φ Cor = m ω v l v r T Methods of actively reducing it by 10 5 Is common mode noise - up to jitter and vibrations Stochastic with bunches 10 3 still need δv vib < 10 4 m/s good vibration isolation 28

40 Preliminary Reach 1 0 Existing Limits 1 2 Log Α Log Λ 1m 29

41 Equivalence Principle New forces often violate EP Way of distinguishing from Gravity Useful for long distances 30

42 Equivalence Principle New forces often violate EP Way of distinguishing from Gravity Useful for long distances New force couples to Z & (A Z) as F (1 + c)z + (1 c)(a Z) 30

43 Equivalence Principle New forces often violate EP Way of distinguishing from Gravity Useful for long distances New force couples to Z & (A Z) as F (1 + c)z + (1 c)(a Z) Introduce ζ Z/A Proton fraction of nucleus a = F m a 0(1 + c ζ) Composition dependent force 30

44 Multiple Isotopic Species Use composition dependent force Perform differential measurements Φ = Φ 1 Φ 2 Different isotopes at same time Φ a 1 a 2 a 0 c(ζ 1 ζ 2 ) Want to maximize isotopic differences δζ Rb 1% δζ Li 7% δζ He 25% δζ H 50% 31

45 Co-Location Electronically identical Nuclear moments differ, atoms see slightly different potential Changes to a null experiment 85 Rb 10 nm 87 Rb V(x) x 32

46 Backgrounds Coriolis is greatly reduced Uncontrolled gravitational sources are not a problem easier environment to find Casimir is important at 0.1 mm Double differential measurement as before 33

47 Outline Motivation for New Forces Atom Interferometry Fifth Force Experiments Deviations in Newtonian Gravity Equivalence Principle Violating Forces Outlook 34

48 Improvements Consider the phase Φ p a T N 2 Φ atom N 2 bunch res Can t make signal bigger Big cost to make taller drop towers Number of bunches sets length of experiment 35

49 Large Momentum Transfer Φ p a T 2 N 1 2 atom N 1 2 bunch changing the frequency to walk up momentum p 10 2 ev E 2 orders of magnitude improvement on long ranged forces 2p no gain on short ranged forces x 10 cm 2 1s 1 p 36

50 Improvements Φ p a T 2 N 1 2 atom N 1 2 bunch Could do more atoms... ψ ( ) N Atom Resolution goes as N 1 2 Atom 37

51 Improvements Φ p a T 2 N 1 2 atom N 1 2 bunch Could do more atoms... ψ ( ) N Atom Resolution goes as N 1 2 Atom ψ ( 1 ) N Atom + ( 2 ) N Atom Resolution goes as N 1 Atom known as Heisenberg Statistics 10 3 Gain! 37

52 Other experiments Equivalence Principle Hogan, Kasevich Precision GR Dimopoulos, Graham, Hogan, Kasevich gr-qc/ Gravity Waves Dimopoulos, Graham, Hogan, Kasevich, Rajendran Electric Neutrality of Atoms Arvanitaki, Dimopoulos, Geraci, Hogan, Kasevich 38

53 Atom Interferometry New method for searching for beyond the SM physics Many possibilities for future improvements Need creativity for new methods of searching 39