LHC Capability for Dark Matter

Transcription

1 LHC Capability for Dark atter 5// Bhaskar Dutta Texas A& University

2 Discovery Time We are about to enter into an era of major discovery Dark atter: we need new particles to explain the content of the universe Standard odel: we need new physics Supersymmetry solves both problems! The super-partners are distributed around GeV to a few TeV LHC: directly probes TeV scale Future results from PLANCK, direct and indirect detection experiments in tandem with the LHC will confirm a model

3 SUSY at the LHC D (or l + l -, τ+τ High P T jet [mass difference is large] Colored particles are produced and they decay finally into the weakly interacting stable particle High P T jet D The p T of jets and leptons depend on the sparticle masses which are given by models (or l + l -, τ+τ R-parity conserving The signal : jets + leptons + missing E T 3

4 SUSY at the LHC Final states odel Parameters Reconstruct sparticle masses, e.g., ~ Q ~ L l,3,4 q + l ~ + χ ~ + χ ~,, ~ χ h ll + χ We may not be able to solve for masses all the sparticles from a model Solving for the SS : Very difficult etc. Identifying one side is very tricky! 4

5 SUSY at the LHC We can use simpler models to understand the cascades and solve for the model parameters The best strategy: Solve for the minimal model: msugra 4 parameters: m, m /, A, tanβ and Sign(μ The cascades can be understood in a simple way [hopefully!] Next step: Next to minimal model (first round of result 5

6 msugra Parameter space Focus point Coannihilation Region Allahverdi, Dutta, Santoso PLB 687:5, The bounds from CDS/enon have started becoming competitive with b s γ and Higgs mass constraints. 6

7 . Coannihilation, GUT Scale In msugra model the lightest stau seems to be naturally close to the lightest neutralino mass especially for large tanβ For example, the lightest selectron mass is related to the lightest neutralino mass in terms of GUT scale parameters: m m +. 5m ~ + (37 GeV / m. 6m E c ~ / Thus for m, E ~ c becomes degenerate with at m / 37 GeV, i.e. the coannihilation region begins at m / (37-4 GeV For larger m / the degeneracy is maintained by increasing m and we get a corridor in the m -m / plane. χ ~χ Arnowitt, Dutta, Santoso The coannihilation channel occurs in most SUGRA models even with nonuniversal soft breaking. 7

8 CA Region at tanβ 4 Δ ~ τ ~ 5 ~ Can we measure Δ at colliders? Can we measure Δ at colliders? χ 5 GeV Arnowitt, Dutta, Gurrola, Kamon, Krislock and Toback PRL, 8 8

9 Smoking Gun of CA Region SUSY asses g~ χ~ χ~ (CD Typical decay chain and final states at the LHC u ~ L 97% % quarks+ τ s +missing energy u u τ ~ τ τ Unique kinematics Jets + τ s+ missing energy Low energy taus characterize the CA region However, one needs to measure the model parameters to predict the dark matter content in this scenario 9

10 CA Region: Final States SUSY asses g~ χ~ u ~ u L 97% ET jet > GeV p Tτ > 4 GeV u jττ & jτ χ~ (CD τ ~ τ τ Excesses in 3 Final States: ae T miss + 4j be T miss + j+τ ce T miss + b +3j Kinematical variables Example of Analysis Chart for b: % p Tτ > GeV ττ & p T(τ ε τ 5%, f fake % for p T vis > GeV

11 Kinematical Variables using a & b 66 equations for 5 SUSY masses peak ( ~ ~ ττ f Δ, χ, χ Slope f( Δ, ~ χ (peak ( j 3 q ~ ~ ~ ττ f L, χ, χ (peak j 4( q ~ ~ ~ τ f L, Δ, χ, χ (peak ( ~ ~ j f5 q ~ τ L, Δ, χ, χ peak f ( g~,q ~ eff 6 L [Next page] Invert the equations to determine the masses 66 GeV [] taus with 4 and GeV; ττ & p Tτ in OS LS technique [] ττ < ττ endpoint ; Jets with E T > GeV; jττ masses for each jet; Choose the nd large value Peak value ~ True Value q ~ L 84 GeV

12 pp g~ g ~ eff miss +4j a E miss T +4j eff E T j +E T j +E T j3 +E T j4 + E T miss [No b jets; ε b ~ 5%] e.g., E T j >, E T j,3,4 > 5 No e s, μ s with p T > GeV eff > 4 GeV; E T miss > max [,. eff ] m / 335 GeV eff peak GeV m / 35 GeV eff peak 74 GeV m / 365 GeV eff peak 33 GeV f ( g~,q ~ 6 L

13 Ω χ D Relic Density in msugra ~ h A, m/ tan β, [] Established the CA region by detecting low energy τ s (p T vis > GeV [] easured 5 SUSY masses (Δ, ~χ, ~χ, q ~, g ~ gaugino Universality at ~5% ( fb - [3] Determine the dark matter relic density q ~, by determining m, m /, tanβ, and A So far using: a E T miss + 4j b E T miss + j+τ peak j ττ peak ττ peak eff? 3 4 / / / /, m, m, m, m,tan β, A,tan β, A 3

14 c E miss T +b+3j eff (b E T jb +E T j +E T j3 +E T j4 + E T miss [j b jet] E T j > GeV, E T j,3,4 > 5 GeV [No e s, μ s with p T > GeV] eff (b > 4 GeV ; E T miss > max [,. eff ] tanβ 48 eff (bpeak 933 GeV tanβ 4 eff (bpeak 6 GeV tanβ 3 eff (bpeak GeV Arbitrary Scale units eff (bpeak (GeV (b eff can be used to probe A and tanβ measuring stop and sbottom masses without 4

15 Determining msugra Parameters Solved by inverting the following functions: peak jττ peak ττ peak eff ( b peak eff 3 4 / / / /, m, m, m, m,tan β, A,tan β, A fb - Ω χ m m / A tan β ± 35 ± 5 4 ± 6 4 ± ~ h A, m/ tan β, L 5 fb fb δω h / Ω ~ ~ χ χ h 6.% (3 fb 4.% (7 fb 5

16 Case : Summary [] The CA region is established by detecting low energy τ s (p T > GeV [] ττ, Slope, jττ, jτ, and eff measure 5 SUSY masses and test gaugino universality at ~5% ( fb - [3] The dark matter relic density is calculated by determining m, m /, tanβ, and A using jττ, eff, ττ, and eff (b δω h / Ω ~ ~ χ χ h 6% (3 fb δσ χ / σ ~ ~ p χ p 7% (3 fb 6

17 . Over-dense D Region A, tanβ 4 m Dilaton effect creates new parameter space m / Lahanas, avromatos, Nanopoulos, PLB649:83-9,7. Smoking gun signals in the region? 7

18 Reference Points m / 44 GeV; m 47 GeV 86.8% m / 6 GeV; m 44 GeV 77.% 8

19 Case (a : Higgs m / 44, m 47, tanβ4, m top 75 g~ 4 u u ~ L 44 E miss T > 8 GeV; N(jet > with E T > GeV; E miss T + E j T + E j T > 6 GeV χ~ χ~ % 87% h 4 e ~ R 5 τ ~ ± χ~ 46 N(b > with P T > GeV;.4< ΔR bb < 9

20 4 Kinematical Variables Side-band BG subtraction end point jbb peak eff ( b peak eff ( bb peak eff 3 4 / / / /,m,m,m,m, tanβ, A, tanβ, A bb (GeV where: m / 4 5 fb 47 w/ side-band BG subtraction m / 48 eff E j T +E j T +E j3 T +E j4 T + E miss T [No b jets; ε b ~ 5%] (b eff E jb T +E j T +E j3 T +E j4 T + E miss T (bb eff E jb T +E jb T +E j3 T +E j4 T + E miss T ( bbj (GeV

21 Determining msugra Parameters Solved by inverting the following functions: end point jbb peak eff ( b peak eff ( bb peak eff 3 4 / / / /,m,m,m,m, tanβ, A, tanβ, A

22 Determining Ωh Solved by inverting the following functions: end point jbb peak eff ( b peak eff ( bb peak eff 3 4 / / / /,m,m,m,m, tanβ, A, tanβ, A fb - m m / A tanβ 47 ± 5 44 ± 5 ± ± 8 L fb Ω χ ~ h A, m/ tan β, δω ~ h / Ω ~ h ~ 5% χ χ Dutta, Gurrola, Kamon, Krislock, Nanopoulos, Lahanas, avromatos, PRD 9

23 Case : Summary Over-dense Dark atter Region: σ OD-CD ~ σ CD / Implication at the LHC: Region where χ decays to Higgs δω CD /Ω CD ~ 5% ( fb - Region where χ decays to stau and Higgs δω CD /Ω CD ~ % (5 fb - 3

24 Case 3 : Focus Point/Hyperbolic Branch m, A, μ, tanβ q ~ l ~ g~ Prospects at the LHC: A few mass measurements are available: nd and 3 rd neutralinos, and gluino ~χ i m /, μ, tanβ Goals: technique on Ωh SUSY mass measurements Can we determine the dark matter content? 4

25 5 μ μ β β β β β β β β χ s c s s c c c s s c c c s s c s W W W W W W W W Μ ~ μ μ β β β β β β β β χ s c s s c c c s s c c c s s c s W W W W W W W W Μ ~ A 4x4 (m /, μ, tanβ g ~ χ χ ~ ~ D 3 3 χ χ ~ ~ D Ωh tan ( β μ Ω χ,, m h / ~ 5 5

26 δd and δd 3 δμ and δ tanβ Example (μ 95, tanβ : assuming δ g ~ / g ~ δd /D δd 3 /D 3 δ tanβ / tanβ δ tanβ / tanβ arbitrary scale arbitrary scale arbitrary scale δd D δμ/μ Let s test this idea: 3 3 fb fb -. 7% δd D 3 3. % δμ/μ δ g ~ 4. 5% ( ( ( ( D. Tovey, Dark atter Searches of ATLAS, PPC 7 ( H. Baer et al., Precision Gluino ass at the LHC in SUSY odels with Decoupled Scalars, Phys. Rev. D75, 95 (7, reporting 8% with fb - g ~ 6

27 Ωh Determination δμ.7% μ δ tanβ ~ 3% tanβ δ m m / / 5. 6% δωh Ωh ~ 8% Dutta, Flanagan, Kamon, Krislock, to appear LHC Goal: D and D 3 at -% and gluino gluino mass at 5% 7

28 Case 4 : Non-U U SUGRA Nature may not be so kind Our studies have been done based on a minimal scenario SUGRA. Let s consider a non-universal scenario: Higgs nonuniversality: m Hu, m Hd m (most plausible extension Steps: Reduce Higgs coupling parameter, μ, by increasing m Hu, ore annihilation (less abundance correct values of Ωh Find smoking gun signals Technique to calculate Ωh 8

29 Reference Point Ωh. Testing msugra and Extensions 9

30 Decays at Reference Point + leptons + leptons So far we have used observables with: leptons + jets, taus + jets, + jets, Higgs + jets In the non-universal scenario: We use W + jets etc 3

31 Extraction of odel Parameters 3

32 Extraction of Observables We collect W+j pairs: related pairs plus random pairs Use jets from the previous events to generate random pairs Normalize and perform: Same jet-previous jet Random pairs will be cancelled Left with only related pairs Successful identification of one side of the production process! 3

33 Jet+ t t invariant mass J+ t invariant mass J+ t invariant mass 33

34 Extraction of odel Parameters eff (m, m / jtt (m, m / jt (m, m /, μ, tanβ jw (m, m /, μ tt (m, m /, μ, tanb P T (low energy tau (m, m /, m, tanb Dutta, Kamon, Kolev, Krislock, to appear m 359 ± GeV, m/ 5.5 ± m 75 ± 5GeV H u.9gev, Wh has 7% uncertainty 34

35 Conclusion Signature contains missing energy (R parity conserving many jets and leptons : Discovering SUSY should not be a problem! Once SUSY is discovered, attempts will be made to measure the sparticle masses (highly non trivial!, establish the model and make connection between particle physics and cosmology Different cosmologically motivated regions of the minimal model have distinct signatures. It is possible to determine model parameters and the relic density based on the LHC measurements non-universal model parameters----can be determined 35