SearchesforQuantumGravityattheLHC

Transcription

1 SearchesforQuantumGravityattheLHC ATLAS Outline Semi Classical Black Holes String Balls Quantum Black Holes Victor Lendermann COST Action MP0905 Universität Heidelberg Bonn,

2 CurrentStatusofLHC ] -1 Total Integrated Luminosity [nb ATLAS Online Luminosity LHC Delivered ATLAS Recorded -1 Total Delivered: 18.1 nb Total Recorded: nb -1 s = 7 TeV 0 24/03 23/04 23/05 23/06 Day in 20 Victor Lendermann, Searches for Quantum Gravity at the LHC 2 COST Action MP0905, Bonn,

3 CurrentStatusofLHC -1 [GeV jet T /dp jet dn jet 1/N ] ATLAS Preliminary s = 7 TeV p jet T anti-k t jets R=0.6 jet >30 GeV y <2.8 Data L PYTHIA -1 dt=1 nb p jet T [GeV] Detector performance looks better than one might expect for first data Good understanding of basic distributions and properties First results of searches for new physics are being prepared Only MC simulation studies in this talk Victor Lendermann, Searches for Quantum Gravity at the LHC 3 COST Action MP0905, Bonn,

4 ExtraDimensions Victor Lendermann, Searches for Quantum Gravity at the LHC 4 COST Action MP0905, Bonn,

5 SignaturesofGravitywithExtraDimensions Perturbative processes Exchange of virtual gravitons Production of real gravitons Strong gravity scenarios Mini black holes String balls Time machines... q _ G l - q l + p p G q jet Victor Lendermann, Searches for Quantum Gravity at the LHC 5 COST Action MP0905, Bonn,

6 SignaturesofGravitywithExtraDimensions Perturbative processes Exchange of virtual gravitons Production of real gravitons Strong gravity scenarios Mini black holes String balls Time machines... q _ G l - q l + p p G q jet Rest of the talk Victor Lendermann, Searches for Quantum Gravity at the LHC 6 COST Action MP0905, Bonn,

7 Big energies small distances. BH forms if partons come closer than 2R S BH mass M 2 BH = ^s Continuous mass spectrum starting at some M M D Exact cross section needs quantum gravity theory. Use semi classical black disc approximation: q R S R S Schwarzschild radius q ^σ = fπr 2 with formation factor f 1 Possible for any combination of quarks and gluons. = BH are charged and coloured R S 1 M D ( MBH M D ) 1 n+1 Banks, Fischler: hep th/ Giddings, Thomas: hep ph/06219 Dimopoulos, Landsberg: hep ph/06295 Victor Lendermann, Searches for Quantum Gravity at the LHC 7 COST Action MP0905, Bonn,

8 BlackHoleEventSimulation Hawking radiation High multiplicity High sphericity Democratic decay example q, g 72% e, µ, τ 11% W ±,Z 8% ν 6% H 2% γ 1% h/l activity 5 : 1 Semi classical model: M BH 5M D Victor Lendermann, Searches for Quantum Gravity at the LHC 8 COST Action MP0905, Bonn,

9 InterestingEventinATLAS 7 Jets 1 Muon ET > 900 GeV E miss T > 0 GeV Victor Lendermann, Searches for Quantum Gravity at the LHC 9 COST Action MP0905, Bonn,

10 BlackHoleEventSelection Different strategies exist. Example for M BH > 5 TeV, M D = 1 TeV, L = 1 fb 1 at s = 14 TeV Cut p T > 2.5 TeV ATLAS CSC book, arxiv: Require at least one well identified lepton e or µ with p T > 50 GeV QCD background further reduced by factor 60 Victor Lendermann, Searches for Quantum Gravity at the LHC COST Action MP0905, Bonn,

11 BlackHoleMassReconstruction p BH = p i + ( /E T, /E T x, /E T y, 0) M BH = ATLAS CSC book, arxiv: p 2 BH Example for M BH > 5 TeV, M D = 1 TeV, s = 14TeV However, turn on behaviour for M BH M D is unknown! Victor Lendermann, Searches for Quantum Gravity at the LHC 11 COST Action MP0905, Bonn,

12 BlackHoleDiscoveryPotential Robust estimation of discovery potential is difficult, because semi classical model assumptions are valid only for M BH M D. Introduce artificial mass cut off in generated samples = conservative estimation M D = 1 TeV, p T > 2.5 TeV, lepton requirement, s = 14 TeV ATLAS CSC book, arxiv: Victor Lendermann, Searches for Quantum Gravity at the LHC 12 COST Action MP0905, Bonn,

13 SearchStrategyforFirstData Little access to M BH > 5 TeV with first data at s = 7 TeV Focus on lower masses Turn on of semiclassical BH production is unknown If M D O(TeV), expect new effects Look for high multiplicity events with different objects with M inv 1 TeV If geometric ^σ = πr 2 S starts at M 1 TeV, cross section would be in nb range Example: string balls Victor Lendermann, Searches for Quantum Gravity at the LHC 13 COST Action MP0905, Bonn,

14 StringBalls String balls excited string states in weakly coupled string theory M s < M D < M s g 2 s } black hole threshold string scale Planck scale string coupling Dimopoulos, Emparan: hep ph/08060 Chamblin, Nayak: hep ph/ Cheung: hep ph/ Gingrich, Martell: arxiv: Cross sections comparable with BH but below GR threshold Typical assumption for highly excited string state: M > 3M s Victor Lendermann, Searches for Quantum Gravity at the LHC 14 COST Action MP0905, Bonn,

15 SearchforStringBalls Analysis strategy similar to BH searches ATLAS PHYS PUB Cross section upper limit for 0 pb 1 at TeV Cross section at 7 TeV D. Gingrich Cross Section [pb] 1 Model Phys Rev D 78, (2008) Upper Limit (95% CL) ATLAS Preliminary Total Cross Section [fb] String Ball Black Hole, n = 3 Black Hole, n = 4 Black Hole, n = 5 Black Hole, n = 6 Black Hole, n = M threshold [TeV] Mass Scale [TeV] String Balls can be excluded up to M 5 TeV with 0 pb 1 at s = TeV In this model, this corresponds to M S 1.5 TeV and M D 2.4 TeV At 7 TeV cross section can still be in pb range for M > 3 TeV Victor Lendermann, Searches for Quantum Gravity at the LHC 15 COST Action MP0905, Bonn,

16 GravityEffectsinContactInteractions Black holes at M M D may appear in contact interactions This can be any quantum gravity effect or resonance Meade, Randall: arxiv: Expect excess at high p T in dijet and dilepton distributions Inv. mass M jj for n = 6 and different M D q M q 0.1 q q M jj / TeV Simplified picture must be smoothed out. Still rather sharp turn on is expected for gravity effects. Good candidate for discovery in first data Victor Lendermann, Searches for Quantum Gravity at the LHC 16 COST Action MP0905, Bonn,

17 SearcheswithDijets Apply the same techniques as for compositeness searches CMS PAS SBM Look for deviations in inclusive spectra Jets/ 50 GeV CMS Preliminary Gen-Level Simulation Pythia simulation at s = 14 TeV QCD & % energy error band Λ + = 5 TeV contact interaction Λ + = 3 TeV contact interaction Jet η < 1, pb Jet p (GeV) T -1 Fractional Difference from QCD LO Calculations QCD Jet η < 1 Energy Err (%) PDF Err (CTEQ 6.1) + Λ = 3 TeV + Λ = 5 TeV CMS Preliminary -1 Errors for pb Requires Very good detector understanding [small uncertainty of jet energy scale] Very good QCD understanding [PDFs, NLO,... ] Jet P T (TeV) Victor Lendermann, Searches for Quantum Gravity at the LHC 17 COST Action MP0905, Bonn,

18 DijetAngularDistributions Example: Dijet ratio = N( η < 0.7) N(0.7 < η < 1.3) CMS PAS SBM Victor Lendermann, Searches for Quantum Gravity at the LHC 18 COST Action MP0905, Bonn,

19 ExclusionorDiscoveryofContactInteractions Using dijet angular distributions CMS PAS SBM Pythia simulation at s = 14 TeV Ratio=N( η <0.7)/N(0.7< η <1.3) QCD GenJets Λ + = 3 TeV Λ + = 5 TeV Λ + = TeV 0 pb -1 CMS Preliminary Ratio=N( η <0.7)/N(0.7< η <1.3) CMS Preliminary Corrected GenJets CaloJets QCD CaloJets Simulation Fit: Corrected y = CaloJets ± Gen-Level Simulation DiJet Mass (GeV) DiJet Mass (GeV) At s = 14 TeV with stat. errors only Excluded Λ (TeV) Discovered Λ (TeV) pb 1 0 pb 1 1 fb 1 pb 1 0 pb 1 1 fb 1 < 5.3 < 8.3 < 12.5 < 4.1 < 6.8 < 9.9 Victor Lendermann, Searches for Quantum Gravity at the LHC 19 COST Action MP0905, Bonn,

20 Conclusions With impressive detector performance in first data, ATLAS and CMS are starting first BSM searches First interesting exclusion limits may be possible even with 0 nb 1 [e.g. for geometric cross section of quantum gravity at M 1 TeV] Evidence for some phenomena is possible with first 1 0 pb 1 of data Dijets, e.g. quantum black holes in contact interactions Multijet quantum gravity effects Victor Lendermann, Searches for Quantum Gravity at the LHC 20 COST Action MP0905, Bonn,

21 Backup Additional Information Victor Lendermann, Searches for Quantum Gravity at the LHC 21 COST Action MP0905, Bonn,

22 PossibleExplanationinStringTheory SM gauge fields cannot go to extra dimensions at such scales. This is ruled out by HEP experiments. But gravity can! String theory SM gauge fields gravity open strings confined to the brain closed strings are free 3d brane String theories require 6 7 extra dimensions, but not necessary of the same size Why gravity? Because it couples to energy/momentum. If gravity cannot go to extra dimensions, then also no other force can. Victor Lendermann, Searches for Quantum Gravity at the LHC 22 COST Action MP0905, Bonn,

23 Vacavant, Hinchliffe: ATLAS PHYS , SN ATLAS Missing E T Spectrum Events / 20 GeV 6 s = 14 TeV jw(eν), jw(µν) jw(τν) ATLAS fast MC studies 5 jz(νν) 5σ discovery sensitivity for 0 fb 1 : 4 total background signal δ=2 M D = 4 TeV signal δ=2 M D = 8 TeV n M D / TeV signal δ=3 M D = 5 TeV signal δ=4 M D = 5 TeV Present limits: 1.4 TeV (δ = 2); 1.0 TeV (δ = 4) 2 No instrumentation effects included E miss T (GeV) Victor Lendermann, Searches for Quantum Gravity at the LHC 23 COST Action MP0905, Bonn,

24 CMS PAS EXO Minimum Luminosity [pb -1 ] CMS Preliminary s = TeV 0 pb -1 δ=4 x x δ=2 200 pb -1 x x 95% CL Exclusion Significance pb -1 [CMS PAS EXO ] CMS Preliminary s = TeV δ=2 δ= MD [TeV] MD [TeV] 5.5 Current limits can be significantly improved with only 5 pb 1 Victor Lendermann, Searches for Quantum Gravity at the LHC 24 COST Action MP0905, Bonn,

25 HawkingRadiation Steven Hawking (1975): Pairs of virtual particles appear at event horizon with one particle escaping Particles have black body spectrum with temperature T H = hc 4πk B R S = 1 4πR S M Pl M Pl M BH No chance to discover Hawking radiation of astro black holes T H < T CMB. In D = 4 + n dimensions (Myers, Perry, 1986) T H = n + 1 ( ) 1 MD n+1 M D (n + 1) 4πR S M BH At high enough T H massive particles are also produced Victor Lendermann, Searches for Quantum Gravity at the LHC 25 COST Action MP0905, Bonn,

26 BlackHoleDecay 1. Balding phase: Graviton radiation. multipole moments are radiated and BH settles down in hairless state. 2. Evaporation phase: M BH M D. Hawking radiation. a) spin down losing angular momentum; b) black body radiation emission of thermally distributed quanta. Most of initial energy is emitted during this phase. Mostly in SM particles. All SM particles on our brane; gravitons also in ED. 3. Planck phase: M BH M D. Regime of quantum gravity. Predictions very difficult. BH decays in some last few SM particles or leaves stable remnant. Pictures: backreaction.blogspot.com Victor Lendermann, Searches for Quantum Gravity at the LHC 26 COST Action MP0905, Bonn,

27 BlackHoleTrigger Single inclusive jet trigger should be very efficient for BH ATLAS BH CSC report Eff. 0% for Thr. E T 400 GeV [for current trigger simulation] 1 Highest E T threshold unprescaled Trigger menu for L = 31 cm 2 s 1 : Highest E T 120 GeV SM rate Hz Trigger menu for L = 33 cm 2 s 1 : Highest E T 330 GeV SM rate Hz Level 1 Level 2 Event Filter ATLAS Trigger Threshold [GeV] In case of detector problems (noise): 3 or 4 jet trigger Alternatively, E T trigger can be used: E T 300 GeV for first data, 1 TeV later Especially important for model independent searches Victor Lendermann, Searches for Quantum Gravity at the LHC 27 COST Action MP0905, Bonn,

28 IdentifyingBlackHoles Need several evidences to be sure. Various ideas exist Hawking radiation democratic decay in MC Look at distributions of particle types: ratios e/µ, e/z 0, e/t... Extract parton cross section and prove that it grows with ^s = M BH Depends on resolution and on turn on behaviour Giddings, Thomas: hep ph/06219 Harris et al.: hep ph/04122 Roy, Cavaglia: arxiv: Parton σ, pb M P, GeV M BH, GeV dσ/dm BH, pb/gev M P = 1 TeV M P = 3 TeV M P = 5 TeV M P = 7 TeV M BH, GeV plots from Dimopoulos, Landsberg: hep ph/06295 Look at event shapes (sphericity, (a)planarity, thrust... ) Victor Lendermann, Searches for Quantum Gravity at the LHC 28 COST Action MP0905, Bonn,

29 IdentifyingBH DistinctionfromSUSY BH are characterised by large /E T tail Example: cut p T > 2.5 TeV, no lepton requirement Should be underestimated, as graviton radiation was not simulated Such high /E T are not typical for SUSY would require high mass neutralino LSP Victor Lendermann, Searches for Quantum Gravity at the LHC 29 COST Action MP0905, Bonn,

30 BlackHoleModelUncertainties Large uncertainties within semiclassical approach. Previously missing features are implemented in new MC versions: Gravition emission Rotation Possible brane tension Conservation of quantum numbers (lepton, flavours) More elaborated final burst models Several analysis strategies are developed for different scenarios. Victor Lendermann, Searches for Quantum Gravity at the LHC 30 COST Action MP0905, Bonn,

31 LimitsinADDModels Astro limits have many uncertainties. Only order of magnitude estimates. In general strong astro limits for n = 2, 3. Weaker for higher n. Colliders can be more sensitive at higher n. Astro signals are sensitive to low energy gravitons modes. Colliders probe mainly high energy gravitons complementary measurements. Victor Lendermann, Searches for Quantum Gravity at the LHC 31 COST Action MP0905, Bonn,

32 BlackHolesinCosmicRays n = 1 n = 7 Anchordoqui, Feng, Goldberg, Shapere: hep ph/ , SM UHE ν BH Horizontal air shower Ultra high energy cosmic ray neutrinos, E ν 19 ev, interact with atmosphere and Earth s crust with cms E 0 TeV. They can produce micro black holes deep in atmosphere, leading to quasi horizontal giant air showers. Deep in atmosphere distinguish from hadronic showers Cross section should be very large Victor Lendermann, Searches for Quantum Gravity at the LHC 32 COST Action MP0905, Bonn,

33 CosmicRayBoundsinADD Anchordoqui, Feng, Goldberg, Shapere: hep ph/ , Using data of Akeno Giant Shower Array (AGASA), Fly s Eye, High Resolution Fly s Eye (HiRes) and Radio Ice Cerenkov Experiment (RICE): M D > TeV for n = 4 7 in ADD. So far the only direct bound on micro black holes. Victor Lendermann, Searches for Quantum Gravity at the LHC 33 COST Action MP0905, Bonn,