Searches for Physics Beyond the Standard Model. Jay Wacker. APS April Meeting SLAC. A Theoretical Perspective. May 4, 2009

Transcription

1 Searches for Physics Beyond the Standard Model A Theoretical Perspective Jay Wacker SLAC APS April Meeting May 4,

2 The Plan Motivations for Physics Beyond the Standard Model New Hints from Dark Matter Possible Interpretations Implications for the LHC 2

3 The hierarchy G Newton /G Fermi = M Planck = G 1 2 Newton = GeV M weak = G 1 2 Fermi = 10 3 GeV M Planck Separated by M weak 3

4 The Hierarchy Problem Big numbers adding up to something small m 2 h = m 2 h bare + y 2 t Λ g 2 Λ 2 If Λ M W ± : a delicate fine-tuning Hints that Λ M W ± 4

5 Naturalness Primary motivation for new theories TeV M P Gauge Hierarchy Problem 1TeV Dynamics stabilizing Higgs mass M W Dynamics predict new particles & resonances Tevatron & LHC are directly testing different theories of naturalness 5

6 Supersymmetry Doubles Standard Model particles Fermion Boson Quark Squark Gluon Gluino Lepton Slepton Photon Neutralino Susy particles at TeV scale Proton stability linked to LSP stability Natural DM candidate Stabilizes the Higgs vev automatically Adds 100+ new parameters Leads to benchmark based searches 6

7 Gauge Coupling Running V (r) = α(r) r α 1 (r) α β log r Counts charged particles All 3 couplings run If couplings were unified at short distances α and sin 2 θ w = α s 7

8 Gauge coupling unification SM 40 1 α sin 2 θ w E (GeV) E GUT 8

9 Gauge coupling unification powerful hint at an organizing principle MSSM 40 1 α sin 2 θ w E (GeV) E GUT 9

10 log Y (x)/y (x=0) Increasing LSP Dark Matter Lightest supersymmetric particle stable χ 0 0 σ Ann v χ 0 σ Ann v SM x m/t Annihilation cross section determines DM abundance σ(χ 0 χ 0 SM)v α2 m 2 χ SM Gauge Coupling DM Mass Fixes DM Mass (w/o hierarchy problem!) = WIMP Miracle m χ 100 GeV LSP: an early Universe relic and could be DM 10

11 Motivations for New Physics haven t changed Hierarchy Problem Gauge Coupling Unification Dark Matter Same story was told in I still find it compelling! 11

12 Anomalies in Indirect & Direct Detection DAMA NaI annual modulation experiment Only non-null direct detection result PAMELA φ(e + ) / φ(e ) E > 100 GeV ATIC } φ(e + e + ) E > 800 GeV Fermi/GLAST INTEGRAL WMAP Haze 511 kev Photons Anomalous synchrotron E < 5 MeV All won t be DM signals If one is, could change expectations for colliders 12

13 Anomalies in Indirect & Direct Detection DAMA NaI annual modulation experiment Only non-null direct detection result PAMELA φ(e + ) / φ(e ) E > 100 GeV ATIC } φ(e + e + ) E > 800 GeV Fermi/GLAST INTEGRAL WMAP Haze 511 kev Photons Anomalous synchrotron E < 5 MeV All won t be DM signals If one is, could change expectations for colliders 12

14 DAMA & Inelastic Dark Matter Consistency with other experiments narrows possibilities (CDMS & XENON10) Tucker-Smith, Weiner (2001) Chang, Kribs, Tucker-Smith, Weiner (2008) Nuclear Recoil Spectrum kevee Multiple, near-degenerate states δm 100 kev χ 2 N m dm + δm m dm χ 2 χ 1 χ 1 N 13

15 Distinctive Recoil Spectrum (E R ) peak µ( m) m v min (E R ) 1 2mER ( me R µ + ) Low recoil energies are suppressed Chang, Pierce, Weiner (2008) 14

16 A New Vector Boson Explanation to DAMA requires inelastic transitions dominating elastic ones Scalars couple to everything Vectors change labels hφ φ h (φ φ 2 2) A µ φ i µ φ A µ φ 1 µ φ 2 15

17 A New Vector Boson Explanation to DAMA requires inelastic transitions dominating elastic ones Scalars couple to everything Vectors change labels hφ φ h (φ φ 2 2) A µ φ i µ φ A µ φ 1 µ φ 2 Choices for how to couple Standard Model vector boson Dark Matter DM has weak charge SM has new gauge charge Photon and Dark Photon Mix 15

18 A New Vector Boson Explanation to DAMA requires inelastic transitions dominating elastic ones Scalars couple to everything Vectors change labels hφ φ h (φ φ 2 2) A µ φ i µ φ A µ φ 1 µ φ 2 Choices for how to couple Standard Model vector boson Dark Matter DM has weak charge SM has new gauge charge Photon and Dark Photon Mix 15

19 Photon & Dark Photon Mixing L =(F µν sm ) 2 +(F µν dm )2 + ɛf µν dm F µν sm + M 2 A 2 dm EM Field strength in gauge invariant Nothing forbids kinetic mixing Holdom (1986) SM charged under new DM force DM neutral under SM forces sm dm ɛe Adm 0 Asm sm dm Arkani-Hamed, Finkbeiner, Slayter, Weiner (2008) 16

20 Photon & Dark Photon Mixing L =(F µν sm ) 2 +(F µν dm )2 + ɛf µν dm F µν sm + M 2 A 2 dm EM Field strength in gauge invariant Nothing forbids kinetic mixing Holdom (1986) SM charged under new DM force DM neutral under SM forces Loop effects generate A sm A dm ɛ 10 3 GUT-scale particles Arkani-Hamed, Finkbeiner, Slayter, Weiner (2008) 16

21 DAMA is a Weak Scale Cross section σ ɛ2 α dm α sm M 4 A dm α2 sm M 4 W ± M Adm ɛ 1 2 MW ± O(1 GeV) Very light state! Can directly produce Dark Photon e A sm e + Adm e e + Best Machines are High Intensity, Low Energy BaBar, Belle, KLOE, CLEO-c, BESIII Essig, Schuster, Toro (2009) 17

22 PAMELA An excess in r e + e = φ(e+ ) Rising towards 100 GeV Could be DM annihilation σ Pamela v σ Freeze out v DM already annihilated! φ(e ) Need an enhancement in annihilation rate A large rate to electrons A small rate to hadrons 18

23 Annihilating to a new light vector Constraints on usual annihilations χ 0 χ 0 W + W hadrons Positrons anti-protons χ 0 χ 0 Dark Photon acts as new long range force σ Pamela v 1 v A dm A dm Increases cross section when DM is cold! electrons positrons Arkani-Hamed, Finkbeiner, Slayter, Weiner (2008) 19

24 Hints that there might be a Dark Sector Must give mass to dark photon Must generate δm dm /m dm 10 6 Alves, Behbahani, Schuster, JW (2009) Standard Dark Model Sector q q dark photon cascade decay l l l l χ 0 χ 0 l l } lepton jets Arkani-Hamed, Finkbeiner, Slayter, Weiner (2008) leptons + MET Light particles in cascade: boosted final states Hidden Valley -like Strassler, Zurek (2006) 20

25 Hints at Dark Matter are not MSSM-like Supersymmetric Standard Model could still be there (now have SM & DM hierarchy problem!) Dark Matter Production could look like Standard Model Dark Sector Susy Cheung, Ruderman, Wang, Yavin (2009) Morrissey, Zurek (2009) 21

26 Bottom of susy spectra matters for searches Neutralino may not be stable Lightest SSM particle could be charged or colored R-parity violation -- Lots of Jets & no MET If LSP is stable, MET could be rare Standard Model Dark Sector Typical Susy event Susy Exceptional Susy decay How robust are the searches to small perturbations? Look inside existing susy searches and vary assumptions 22

27 Most BSM searches based on Susy Susy carries a lot of baggage from 28 years of study SOFTLY BROKEN SUPERSYMMETRY AND SU(5) Savas DIMOPOULOS 1' 2 Institute of Theoretical Physics, Stanford University, Institute of Theoretical Physics, University of California, Santa Barbara and University of Michigan, Ann Arbor, USA Howard GEORGI 3 Lyman Laboratory of Physics, Harvard University, Cambridge, MA 02138, USA Received 2 June 1981 Here we explore a simpler alternative possibility-that the supersymmetry is broken explicitly, but softly, by terms of dimension less than four in the lagrangian. We add to the lagrangian (not to v) the following SU(5) invariant mass terms, all of the order of a TeV: (1) a positive mass squared term for the matter bosons; (2) a mass for the Higgs fermions (and their SU(5) partners); (3) a Majorana mass for the gauge fermions; (4) a negative mass squared term for the boson fields in the ~ supermultiplet; (5) a mixed (with positive and negative eigenvalues) mass squared matrix for the Higgs bosons. 23

28 msugra has 5 parameters Only 2 are relevant for collider searches Colored states EW states Mass m 0 m 1 2 M weak E M GUT Many relations between masses Driven by an ansätz, not consistency Tuning searches to msugra, limits applicability to other models 24

29 msugra Caveats Gaugino mass running is multiplicative: m B : m W : m g 1 : 2 : 7 g B + q q Always have very hard jets What if m B : m g 1 : 1.5? Jets become softer Challenge to increase S/B, but possible! In non-susy theories, mass splittings may be different m ~ B m W m g = m 1 + im 2 25

30 Tevatron Sensitivity Plot Bino Mass GeV m g 120 GeV m g 130 GeV g χ jj X Tevatron s existing searches don t cover but potential sensitivity g χ jj χ jj + jj Gluino Mass GeV Alwall, Le, Lisanti, JW (2008) 26

31 Results from DM experiments change LHC expectations If DM is not the LSP: search philosophy for BSM may be ineffective Should scrub searches of irrelevant theoretical assumptions Is the full msugra framework needed to search for Jets + MET? Possible to cut away a visible signal (e.g. additive vs multiplicative renormalization) Excess baggage usually avoidable Search for simplified models More robust against small changes in spectra Alwall, Schuster, Toro (2008) Dark matter may be pointing to novel final states! 27

32 Dark Matter Hierarchy Problem 28

33 Dark Matter??? Hierarchy Problem Supersymmetry Compositeness 28

34 Dark Matter??? Hierarchy Problem Supersymmetry Compositeness??? 28