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M.Savina, November 25, NPD RAS 2009 1 Black Hole Production at the LHC: peculiarities, problems, expectations Savina Maria JINR, Dubna

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2 M.Savina, November 25, NPD RAS 2009 Part I. Optimistic Symphony – The Old Predictions D-dimensional (D>4) models – possible realizations of TeV-scale gravity BH in D dimensions: formation, decay, experimental expectations Predictions for the LHC, event generators for BH production, benefits and limitations

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3 M.Savina, November 25, NPD RAS 2009 Black Hole formation in TeV-scale gravity Black Hole formation in TeV-scale gravity Pictures by Sabine Hossenfelder In large extra dimension models Gravity stronger at small distances Horizon radius larger For M ~ TeV it increases to 10 -4 fm For these BH R h << R and they have approximately higher dimensional spherical symmetry At the LHC partons can come closer than their Schwarzschild horizon a black hole production

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4 M.Savina, November 25, NPD RAS 2009 BH Production in pp collisions: some well-known formulas BH Production in pp collisions: some well-known formulas Schwarzschild raduis of a multidimensional BH (as given by R. Meyers, M. Perry) BH production cross section Differential BH production cross section PDF’s

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5 M.Savina, November 25, NPD RAS 2009 BH Production in pp collisions at the LHC BH Production in pp collisions at the LHC Increasing cross section, no suppression from small couplings

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6 M.Savina, November 25, NPD RAS 2009 Hawking evaporation of BH Hawking temperature where Multiplicity of produced particles in BH decay

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7 M.Savina, November 25, NPD RAS 2009 Grey Body Factors for BH Decay Grey Body Factors for BH Decay Grey body factors # D.o.F. for e- # D.o.F. for GB

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8 M.Savina, November 25, NPD RAS 2009 Entropy, BH decay and M min (BH) BH Entropy Democratic decay blinded to flavor: probabilities are the same for all species (violation of some conservation laws) The ratio of hadronic/leptonic is 5 : 1 S BH must be large enough to reproduce thermal BH decay S BH > 25

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9 M.Savina, November 25, NPD RAS 2009 BH Production in pp collisions at the LHC BH Production in pp collisions at the LHC DL ‘01 For the LHC energies: a) Parton-level production cross section b) Differential cross section c)Hawking temperature d)Average decay multiplicity for Schwarzschild BH n=4

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10 M.Savina, November 25, NPD RAS 2009 Black Hole or String Ball? Black Hole or String Ball? M BH >> M D : semiclassical well-known description for BH’s. What happens when M BH approach M D ? BH becomes “stringy”, their properties become complex.

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11 M.Savina, November 25, NPD RAS 2009 Black Hole vs String Ball Production Black Hole vs String Ball Production Matching: smooth transition between two regimes Production cross section:

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12 M.Savina, November 25, NPD RAS 2009 Production cross section for BH, SB and p-brane Production cross section for BH, SB and p-brane

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13 M.Savina, November 25, NPD RAS 2009 Final state of the SM process vs typical BH decay spectra Multi-jet and hard leptons events, spherical, typical temperature about 200 GeV Pictures by Sabine Hossenfelder SM BH decay

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14 M.Savina, November 25, NPD RAS 2009 BH Experimental Signatures BH Experimental Signatures Potentially large cross sections, approaching 10 3 fm or more An increase of cross sections with energy, according to an absense of gauge coupling suppression (will be hard to see at the LHC) Relatively high sphericity for final states High multiplicity as proportional to the BH entropy of particles produced (primaries) Hard trasverse leptons an jets, in significant numbers Approximately thermally determined ratios of species (democratic decay) Suppression of highest-energy jets Decrease of decay primary (lepton/parton) energy with total event transverse energy (resulting from decreasing Hawking temperature with mass)

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15 M.Savina, November 25, NPD RAS 2009 BH Production Generators BH Production Generators TRUENOIR CHARYBDIS(C.M. Harris, P. Richardson, B.R. Webber ’03) The very first BH generator. Conservation of baryon and lepton numbers, QCD colors. Rapid decay approximation. No GBF, temperature variation during Hawking stage, no spindown phase In use in collaborations now. More progressive than Truenoir. Proper to Les Houches format event convention. GBF, temperature evolution during thernal phase, two choices of PDF scale, Number of remnants in Planck phase As earlier: No simulation for spindown phase and old results for entropy (underestimation of BH lifetime and some differences in Multiplicities of primery produced particles) Up to now we have no correct BH generator, in which all stages of BH evolution would be included !!

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16 M.Savina, November 25, NPD RAS 2009 CHARIBDIS Parameters CHARIBDIS Parameters

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17 M.Savina, November 25, NPD RAS 2009 CHARYBDIS Simulation Results CHARYBDIS Simulation Results w/o temp. variation w/o GBF M=5.0-5.5 TeV Higgs boson spectrum Electron and Positron spectra

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18 M.Savina, November 25, NPD RAS 2009 CHARYBDIS Simulation Results CHARYBDIS Simulation Results Effects from remnants at the end of Planck stage: w /wo

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19 M.Savina, November 25, NPD RAS 2009 CHARYBDIS Gen.: Analysis and results for the CMS CHARYBDIS Gen.: Analysis and results for the CMS M_rec Sphericity CMS PTDR Vol. II, 2007 Hard jets, leptons and γ’s L = 30 fb -1 As a benchmark: 2 TeV/c 2 fundamental Planck scale 4 TeV/c 2 – 14 TeV/c 2 BH mass n=3 number of ED

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20 M.Savina, November 25, NPD RAS 2009 CHARYBDIS Gen.: Analysis and results for the CMS CHARYBDIS Gen.: Analysis and results for the CMS Event selection: The total p T of all reconstrected objects plus missing E T is larger then 2500 GeV Level-1 and HLT trigger included 4-jet trigger (with 93 % efficiency) The CMS mass reach: For L = 10 – 100 pb -1 and M D = 2 – 3 TeV M min (BH) up to 4 TeV and n = 2 – 6.

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21 M.Savina, November 25, NPD RAS 2009 Optimistic Resume: BH wil be produced at the LHC with enormous rate up to about 1 KHz (for L = 100 fb -1 ) BH is spectacular clear experimental signature: a “fireball” decay, spherically symmetric, large multiplicity of hard jets, leptons, photons, thermal “democratic” spectra BH production may be the very first evidence for the ED (much earlier then KK modes and missing energy signals from different ED models) because its huge rate.

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22 M.Savina, November 25, NPD RAS 2009 Part II. Optimism Is fading… BH not as spectacular as advertized!! BH Production near the threshold and careful counting Conventions on a fundamental mass Inelasticity for BH formation at the LHC and in the UHECR Minimal M for a sensible definition of a BH LHC unlikely to make classical BH with thermal decay spectra. So, what can we see, then? Two-body final states and QG … but it is not the end of the story

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23 M.Savina, November 25, NPD RAS 2009 L. Randall’s Talk at String’07:

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24 M.Savina, November 25, NPD RAS 2009 Conventions on a fundamental mass Conventions on a fundamental mass D=6 D=10 At least three definitions: Just numerical coefficients But: there is essential difference between M about 1 TeV and 2 TeV for the LHC!

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25 M.Savina, November 25, NPD RAS 2009 At what energy can we safely speak about true BH prods? At what energy can we safely speak about true BH prods? Clearly E > M D. But how much large?

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26 M.Savina, November 25, NPD RAS 2009

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27 M.Savina, November 25, NPD RAS 2009 Inelasticity in BH Production and X min Inelasticity in BH Production and X min Production efficiency curve, for example: What part of initial collision energy actually was trapped in BH formation process? inelasticity

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28 M.Savina, November 25, NPD RAS 2009 BH Production in UHECR n=1-7, 5 Yrs. Pierre-Auger Observatory

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29 M.Savina, November 25, NPD RAS 2009 Inelasticity and BH Production at the LHC and at the PAO Inelasticity and BH Production at the LHC and at the PAO Inelasticity is much more restrictive factor for the LHC because it is limited in energy by 14 TeV

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30 M.Savina, November 25, NPD RAS 2009 The discovery reaches for the LHC The discovery reaches for the LHC This region excluded by PAO n=6

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31 M.Savina, November 25, NPD RAS 2009 Who is “pessimist” ? Pessimist is au fait optimist… Resume (not hard and final, because too many calculations and theoretical Investigation are waiting to be done in this field) Black Holes is not a such spectacular signature as commonly advertized earlier (from the very first papers in 1998). Likely the LHC will not be able to observe classical thermal BH decays. Careful counting pushes the minimal value of BH mass to higher energies what make observation of BH hopeless at the LHC (important moment: there are alternative point of views on this problem, not just one possible). In any case for TeV scale gravity near the threshold we will see signatures of QG (if one of them are realized by Nature). We can’t calculate its and make quantitative prediction. But these signatures can be distinguished from other possible new physics (by high transversality for final states). Futher experimental technics?

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