Micro Black Holes

1. Micro Black Holes in the atlas detector Nick Brett and C. Issever University of Oxford ATLAS Physics Workshop - Rome - 08.06.2005

2. Rs Black Holes At The LHC If Mpl ~ O(1 TeV)  Black Hole Production possible at LHC N.Arkani-Hamed, S. Dimopoulos and G.R.Dvali [hep-ph/9803315] S.Dimopoulos and G. Landsberg [hep-ph/0106295] σ ~ πRS2 ~ O(100)pb LHC  Black Hole Factory BH lifetime ~ 10-27 – 10-25 seconds Decays with equal probability to all particles via Hawking Radiation MBH = √S Parton Parton MBH~MPL: Study Quantum Gravity at the LHC Rs = Schwarzschild radius Nick Brett - University of Oxford

3. Black Hole Decay • Decay via Hawking Radiation • Emit particles following an approximately black body thermal spectrum n = number of extra dimensions Spectrum modified by Grey Body factors Black Hole might not maintain Thermal equilibrium Astronomic BH -- COLD -- No Evaporation Micro BH -- HOT -- Evaporation Nick Brett - University of Oxford

4. Black Hole Event in ATLAS BH evaporates into (q and g : leptons : Z and W : n and G : H) = (72%:11%:8%:6%:2%:1%) (hadron : lepton) is (5 : 1) accounting for t, W, Z and H decays S.B. Giddings, S. Thomas, Phys.Rev.D65(2002)056010 gamma Decay of 6.1 TeV Black Hole High multiplicity events Muon J. Tanaka, “Search for Black Holes”, 24th May 2003 at Athens Nick Brett - University of Oxford

5. Black Hole Simulation Study of Black Holes with the ATLAS detector at the LHC (J.Tanaka, T.Yamamura, S.Asai,J.Kanzaki) ATL-PHYS-2003-037 Black Holes at Future Colliders and Beyond (G.Landsberg) HEP-PH/0205174 CHARYBDIS: A Black Hole Event Generator (C.M. Harris, P.Richardson and B.R. Webber) CERN-TH / 2003-170 Charybdis Event Generator was Selected Accounts for grey body factors Allows for temperature variation across black hole decay Includes recoil of black hole against decay products Aimed to extend atlfast results of JHEP05(2005)053 in full simulation Nick Brett - University of Oxford

6. Black Hole Simulation The following data sets have been produced with Charybdis Karina Flavia Loureiro and the Grid submission team have produced the following Nick Brett - University of Oxford

7. Number of Extra dimensions 2 4 6 Event Multiplicity (atlfast) High multiplicity events Multiplicity increases with MBH Multiplicity decreases with n Nick Brett - University of Oxford

8. Number of Extra dimensions 2 4 6 Event Multiplicity (atlfast) 5 TeV n = 2,4 and 6 sample 104 events each (atlfast) Nick Brett - University of Oxford

9. atlfast full sim Event Multiplicity Have applied the following cuts so far Electrons isEM & 0x7FF = 0 Et > 30GeV Delta eta < 0.01 Delta phi < 0.02 E/P(barrel) 0.8–1.3 E/P(endcap) 0.7–2.5 Photons No Cuts Muons Combined Muon Rec Jets Ehad/Eem > 0.2 6.0 – 6.5 TeV n = 2 sample Nick Brett - University of Oxford

10. Missing Et 6.0 – 6.5 TeV n=2 sample (full simulation) JHEP052005053 (atlfast) Background Missing Et Cut Nick Brett - University of Oxford

11. Mass Reconstruction Mass Reconstructed by summing 4-momenta of all decay products • Minimum of 4 jets • PT of 3 leading jets > 500, 400, 300 GeV respectively • Missing ET < 100 GeV • Eta < 2.5 The following cuts were applied: Cuts taken from JHEP05(2005)053 Nick Brett - University of Oxford

12. Reconstructed BH Mass (atlfast) BH will be produced with a range of masses at LHC Mass reconstruction by Σ P of all decay products Mass Resolution ? Offset due to detector acceptance and energy scale? Nick Brett - University of Oxford

13. Reconstructed BH Mass (full sim) 6.0 – 6.5 TeV n=2 sample • Problems with double counting • Improving Particle ID should reduce the problem • A more robust method will be necessary • Need to correct for detector acceptance and efficiencies Nick Brett - University of Oxford

14. Temperature Reconstruction Temperature reconstructed by fitting black body spectrum to electron energy distribution • Minimum of 4 jets • PT of 3 leading jets > 500, 400 and 300 GeV respectively • Missing PT < 100 GeV • Electron η < 2.5 • Electron ET > 30 GeV The following cuts were applied: Cuts taken from JHEP05(2005)053 Nick Brett - University of Oxford

15. Reconstructed Temperature 5 – 14 TeV sample with n = 2 (atlfast) Problems • Electrons are boosted by Black hole recoil • Electrons are not all from the event horizon (secondaries) • Theoretical uncertainties over Temperature variation during decay Alternative methods are proposed in JHEP 05(2005)053 • Attempt to determine decay chain • Use Leading decay product to sample a small section of the Black Body distribution Nick Brett - University of Oxford

16. Summary and Outlook • Studied BH signals in ATLFAST • Extended results of JHEP05(2005)053 in full simulation • Problems with double counting • Need more statistics in full simulation • Must understand electron, muon, photon and jet collections • Have made progress with electrons and jets • Working with Karina Flavia Loureiro to understand event shape • Aim to Reconstruct BH mass and Temperature • Will explore temperature reconstruction methods outlined in JHEP05(2005)053 • Plan to study backgrounds and systematics (inc. PDF uncertainty) Nick Brett - University of Oxford