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Out-of-this-World Physics: From Particles to Black Holes Greg Landsberg L.G.Landsberg Symposium L.G.Landsberg Symposium December 19, 2005.

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Presentation on theme: "Out-of-this-World Physics: From Particles to Black Holes Greg Landsberg L.G.Landsberg Symposium L.G.Landsberg Symposium December 19, 2005."— Presentation transcript:

1 Out-of-this-World Physics: From Particles to Black Holes Greg Landsberg L.G.Landsberg Symposium L.G.Landsberg Symposium December 19, 2005

2 2December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black HolesOutline A Word on Hierarchies Standard Model: Beauty and the Beast How to Make Gravity Strong? Looking for Extra Dimensions… Production of Black Holes at Colliders

3 3December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes N.B. Large Hierarchies Tend to Collapse...

4 4December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Hierarchy of the Standard Model Extra dimensions might get rid of the beast while preserving the beauty! Beauty … vev M GUT M Pl Gravitational Force E [GeV] EM/Hypercharge Force Weak Force Strong Force Inverse Strength RGE evolution and the Beast

5 5December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes But Keep in Mind… Fine tuning (required to keep a large hierarchy stable) exists in Nature: Solar eclipse: angular size of the sun is the same as the angular size of the moon within 2.5% (pure coincidence!) Politics: Florida recount, 2,913,321/2,913,144 = Numerology: / = (HW Assignment: is it really numerology?) But: beware the anthropic principle Properties of the universe are special because we exist in it Don’t give up science for philosophy: so far we have been able to explain how the universe works entirely by science

6 6December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Math Meets Physics Math physics: some dimensionalities are quite special Example: Laplace equation in two dimensions has a logarithmic solution; for any higher number of dimensions it obeys the power law Some of these peculiarities exhibit themselves in condensed matter physics, e.g. diffusion equation solution allows for long-range correlations in 2D- systems (cf. flocking) Modern view in topology: one dimension is trivial; two and three spatial dimensions are special (properties are defined by the topology); any higher number is not Do we live in a special space, or only believe that we are special?

7 7December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes The ADD Model SM fields are localized on the (3+1)-brane; gravity is the only force that “feels” the bulk space What about Newton’s law? Ruled out for infinite extra dimensions, but does not apply for sufficiently small compact ones Gravity is fundamentally strong force, bit we do not feel that as it is diluted by the volume of the bulk G ’ N = 1/M D 2 ; M D  1 TeV More precisely, from Gauss’s law: Amazing as it is, but no one has tested Newton’s law to distances less than  1mm (as of 1998) Thus, the fundamental Planck scale could be as low as 1 TeV for n > 1

8 8December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Longitudinal ED Simultaneously, another idea has appeared: Explore modification of the RGE in (4+n)-dimensions to achieve low-energy unification of the gauge forces [Dienes, Dudas, Gherghetta, PL B436, 55 (1998)] To achieve that, allow gauge bosons (g, , W, and Z) to propagate in an extra dimension, which is “longitudinal” to the SM brane and compactified on a “natural” EW scale: R ~ 1 TeV -1 MZMZ M GUT M Pl =1/  G N MSMS M’ GUT Gravitational Force logE EM/Hypercharge Force Weak Force Strong Force Real GUT Scale Virtual Image Inverse Strength M’ Pl  ~ 1 TeV

9 9December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Randall-Sundrum Scenario Randall-Sundrum (RS) scenario [PRL 83, 3370 (1999); PRL 83, 4690 (1999)] + brane – no low energy effects +– branes – TeV Kaluza-Klein modes of graviton Low energy effects on SM brane are given by   ; for kr c ~ 10,   ~ 1 TeV and the hierarchy problem is solved naturally G Planck brane x5x5 SM brane r Planck brane (  = 0) SM brane (  ) AdS 5  k: AdS curvature Reduced Planck mass: AdS

10 10December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Differences Between the Models ADD Model: Pro: “Eliminates” the hierarchy problem by stating that physics ends at a TeV scale Only gravity lives in the “bulk” space Size of ED’s (n=2-7) between ~100  m and ~1 fm Black holes at the LHC and in the interactions of UHE cosmic rays Con: Doesn’t explain why ED are so large TeV -1 Scenario: Pro: Lowers GUT scale by changing running of the couplings Only gauge bosons (g/  /W/Z) “live” in ED’s Size of ED’s ~1 TeV -1 or ~ m Con: Gravity is not in the picture RS Model: Pro: A rigorous solution to the hierarchy problem via localization of gravity Gravitons (and possibly other particles) propagate in a single ED, w/ special metric Con: Size of ED as small as ~1/M Pl or ~ m G Planck brane x5x5 SM brane

11 11December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Kaluza-Klein Spectrum ADD Model: Winding modes with energy spacing ~1/r, i.e. 1 meV – 100 MeV Can’t resolve these modes – they appear as continuous spectrum TeV -1 Scenario: Winding modes with nearly equal energy spacing ~1/r, i.e. ~TeV Can excite individual modes at colliders or look for indirect effects RS Model: “Particle in a box” with a special metric Energy eigenvalues are given by zeroes of Bessel function J 1 Light modes might be accessible at colliders ~1 TeV E ~M GUT E … M0M0 MiMi ~M Pl E … M1M1 MiMi Gravitational coupling per mode; many modes gege G N for zero-mode; ~1/   for others M0M0

12 12December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Using the ED Paradigm EWSB from extra dimensions: Hall, Kolda [PL B459, 213 (1999)] (lifted Higgs mass constraints) Antoniadis, Benakli, Quiros [NP B583, 35 (2000)] (EWSB from strings in ED) Cheng, Dobrescu, Hill [NP B589, 249 (2000)] (strong dynamics from ED) Mirabelli, Schmaltz [PR D61, (2000)] (Yukawa couplings from split left- and right-handed fermions in ED) Barbieri, Hall, Namura [hep-ph/ ] (radiative EWSB via t- quark in the bulk) Flavor/CP physics from ED: Arkani-Hamed, Hall, Smith, Weiner [PRD 61, (2000)] (flavor/CP breaking fields on distant branes in ED) Huang, Li, Wei, Yan [hep-ph/ ] (CP-violating phases from moduli fields in ED) Neutrino masses and oscillations from ED: Arkani-Hamed, Dimopoulos, Dvali, March-Russell [hep-ph/ ] (light Dirac neutrinos from right-handed neutrinos in the bulk or light Majorana neutrinos from lepton number breaking on distant branes) Dienes, Dudas, Gherghetta [NP B557, 25 (1999)] (light neutrinos from right-handed neutrinos in ED or ED see-saw mechanism) Dienes, Sarcevic [PL B500, 133 (2001)] (neutrino oscillations w/o mixing via couplings to bulk fields) Many other topics from Higgs to dark matter

13 13December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes ED and Flavor Physics ED models offer a powerful paradigm for explaining flavor sector and CP-violation New amplitudes and phases could be transmitted to our world via gravity (or other bulk fields), thus naturally introducing small parameters needed for description of CP-violation, flavor physics, etc. Some realizations of this class of models give realistic CKM matrix (e.g., Arkani-Hamed, Hall, Smith, Weiner [PRD 61, (2000)]) The idea of “shining” mentioned in the original ADD papers could explain why these effects were stronger in early universe SM bulk gauge fields via gravity bulk big bang “CP-brane” “shining” SM

14 14December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Flavor Physics from Geometry Arkani-Hamed/Schmaltz [Phys. Rev. D61, (2000)] – split fermions embedded in a “fat” brane Wave-functions of different families of quarks and leptons are spatially offset, thus the overlap areas are reduced exponentially A fruitful paradigm to build models of flavor and mixing with automatically suppressed FCNC and stable proton Possible to construct realistic CKM matrices via geometry of extra brane Similar attempts in Randall-Sundrum class of models In some of these models LFV decays of kaons are predicted and could be sought Quark doublets of 3 generations Quark singlets of 3 generations Branco/de Gouvea/Rebelo [Phys. Lett. B506, 115 (2001)] Huber [NP 666, 269 (2003)]

15 15December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Sub-millimeter gravity measurements could probe only n=2 case only within the ADD model The best sensitivity so far have been achieved in the U of Washington torsion balance experiment – a high- tech “remake” of the 1798 Cavendish experiment R 1.7 TeV) Sensitivity vanishes quickly with the distance – can’t push limits further down significantly Started restricting ADD with 2 extra dimensions; can’t probe any higher number Ultimately push the sensitivity by a factor of two in terms of the distance No sensitivity to the TeV -1 and RS models Tabletop Gravity Experiments PRL 86, 1418 (2001) E.Adelberger et al. ~ ~ [J. Long, J. Price, hep-ph/ ]

16 16December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Astrophysical and Cosmological Constraints Supernova cooling due to graviton emission – an alternative cooling mechanism that would decrease the dominant cooling via neutrino emission Tightest limits on any additional cooling sources come from the measurement of the SN1987A neutrino flux by the Kamiokande and IMB Application to the ADD scenario [Cullen and Perelstein, PRL 83, 268 (1999); Hanhart, Phillips, Reddy, and Savage, Nucl. Phys. B595, 335 (2001)]: M D > TeV (n=2) M D > 2-4 TeV (n=3) Distortion of the cosmic diffuse gamma radiation (CDG) spectrum due to the G KK   decays [Hall and Smith, PRD 60, (1999)]: M D > 100 TeV (n=2) M D > 5 TeV (n=3) Overclosure of the universe, matter dominance in the early universe [Fairbairn, Phys. Lett. B508, 335 (2001); Fairbairn, Griffiths, JHEP 0202, 024 (2002)] M D > 86 TeV (n=2) M D > 7.4 TeV (n=3) Neutron star  -emission from radiative decays of the gravitons trapped during the supernova collapse [Hannestad and Raffelt, PRL 88, (2002)]: M D > 1700 TeV (n=2) M D > 60 TeV (n=3) Caveat: there are many known (and unknown!) uncertainties, so the cosmological bounds are reliable only as an order of magnitude estimate Still, n=2 is largely disfavored

17 17December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Collider Signatures for Large ED Kaluza-Klein gravitons couple to the energy-momentum tensor, and therefore contribute to most of the SM processes For Feynman rules for G KK see: [Han, Lykken, Zhang, PRD 59, (1999)] [Giudice, Rattazzi, Wells, NP B544, 3 (1999)] Since graviton can propagate in the bulk, energy and momentum are not conserved in the G KK emission from the point of view of our 3+1 space-time Depending on whether the G KK leaves our world or remains virtual, the collider signatures include single photons/Z/jets with missing E T or fermion/vector boson pair production Graviton emission: direct sensitivity to the fundamental Planck scale M D Virtual effects: sensitive to the ultraviolet cutoff M S, expected to be ~M D (and likely < M D ) The two processes are complementary Real Graviton Emission Monojets at hadron colliders G KK g q q g g g Single VB at hadron or e + e - colliders G KK V V V V Virtual Graviton Effects Fermion or VB pairs at hadron or e + e - colliders V V G KK f f f f

18 18December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes L’EPilogue (Large ED) Experiment eeee   qqf  WWZZ Combined ALEPH / /0.46 (bb) /1.00 (<189) DELPHI /0.76 (ff) (<202) L /1.1 (<202) OPAL /1.03 (<209) Color coding  184 GeV  189 GeV >200 GeV =-1 =+1 GL Virtual Graviton Exchange ee  Gee  Ge  e   ZG Experiment n=2n=3n=4n=5n=6n=2n=3n=4n=5n=6 ALEPH DELPHI L OPAL LEP Combined: 1.2/1.1 TeV All limits are in TeV

19 19December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Colliders: Graviton Emission ee   + G KK at LEP  + ME T final state M P > TeV (ADLO), for n=2…7 qq/gg  q/g + G KK at the Tevatron jets + ME T final state Z( )+jets is irreducible background Challenging signature due to large instrumental backgrounds from jet mismeasurement, cosmics, etc. DØ pioneered this search and set limits [PRL, (2003)] M P > TeV for n=2…7 Later, CDF achieved slightly better limits Expected reach for Run II/LHC: Theory: [Giudice, Rattazzi, Wells, Nucl. Phys. B544, 3 (1999) and corrected version, hep-ph/ ] [Mirabelli, Perelstein, Peskin, PRL 82, 2236 (1999)] nM D reach, Run I M D reach, Run II M D reach, LHC 100 fb GeV1400 GeV8.5 TeV 3950 GeV1150 GeV6.8 TeV 4850 GeV1000 GeV5.8 TeV 5700 GeV900 GeV5.0 TeV [PRL 90, (2003)] G KK g q q 85 pb -1

20 20December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Tevatron: Virtual Graviton Effects Expect an interference with the SM fermion or boson pair production High-mass, low |cos   | tail is a characteristic signature of LED [Cheung, GL, PRD (2000)] Best limits on the effective Planck scale come from new DØ Run II data: M Pl > TeV (n=2-7) Combined with the Run I DØ result: M Pl > TeV – tightest to date Sensitivity in Run II and at the LHC: V V G KK f f f f Run II, 200 pb -1

21 21December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Interesting Candidate Events While the D Ø data are consistent with the SM, the two highest- mass candidates have anomalously low value of cos  * typical of ED signal: Event Callas: M ee = 475 GeV, cos  * = 0.01 Event Farrar: M  = 436 GeV, cos  * = 0.03

22 22December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Intermediate-size extra dimensions with  TeV -1 radius Introduced by Antoniadis [PL B246, 377 (1990)] in the string theory context; used by Dienes, Dudas, Gherghetta [PL B436, 55 (1998)] to allow for low-energy unification Expect Z KK, W KK, g KK resonances at the LHC energies At lower energies, can study effects of virtual exchange of the Kaluza-Klein modes of vector bosons Current indirect constraints come from precision EW measurements: 1/r ~ 6 TeV No dedicated experimental searches at colliders to date Antoniadis, Benaklis, Quiros [PL B460, 176 (1999)] Z KK TeV -1 Extra Dimensions

23 23December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes First Dedicated Search for TeV -1 Extra Dimensions While the Tevatron sensitivity is inferior to indirect limits, it explores the effects of virtual KK modes at higher energies, i.e. complementary to those in the EW data D Ø has performed the first dedicated search of this kind in the dielectron channel based on 200 pb -1 of Run II data (Z KK,  KK  e + e - ) The 2D-technique similar to the search for ADD effects in the virtual exchange yields the best sensitivity in the DY production [Cheung, GL, PRD 65, (2002)] Data agree with the SM predictions, which resulted in the following limit: 1/R > % CL R < 1.75 x m 200 pb -1, e + e - Event Callas Interference effect 1/R = 0.8 TeV

24 24December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Randall-Sundrum Model Observables Need only two parameters to define the model: k and r c Equivalent set of parameters: The mass of the first KK mode, M 1 Dimensionless coupling Drell-Yan at the LHC M1M1 Davoudiasl, Hewett, Rizzo [PRD 63, (2001)] To avoid fine-tuning and non- perturbative regime, coupling can’t be too large or too small 0.01 ≤ ≤ 0.10 is the expected range Gravitons are narrow Expected Run II sensitivity in DY

25 25December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes First Search for RS Gravitons Already better limits than sensitivity for Run II, as predicted by phenomenologists! Assume fixed K-factor of 1.3 for the signal The tightest limits on RS gravitons to date [PRL 95, (2005)]

26 26December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Black Holes on Demand NYT, 9/11/01

27 27December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Theoretical Framework Based on the work done with Dimopoulos a few years ago [PRL 87, (2001)] and a related study by Giddings/Thomas [PRD 65, (2002)] Extends previous theoretical studies by Argyres/Dimopoulos/March-Russell [PL B441, 96 (1998)], Banks/Fischler [JHEP, 9906, 014 (1999)], Emparan/Horowitz/Myers [PRL 85, 499 (2000)] to collider phenomenology Big surprise: BH production is not an exotic remote possibility, but the dominant effect! Main idea: when the c.o.m. energy reaches the fundamental Planck scale, a BH is formed; cross section is given by the black disk approximation: Geometrical cross section approximation was argued in early follow-up work by Voloshin [PL B518, 137 (2001) and PL B524, 376 (2002)] More detailed studies showed that the criticism does not hold: Dimopoulos/Emparan – string theory calculations [PL B526, 393 (2002)] Eardley/Giddings – full GR calculations for high-energy collisions with an impact parameter [PRD 66, (2002)]; extends earlier d’Eath and Payne work Yoshino/Nambu - further generalization of the above work [PRD 66, (2002); PRD 67, (2003)] Hsu – path integral approach w/ quantum corrections [PL B555, 29 (2003)] Jevicki/Thaler – Gibbons-Hawking action used in Voloshin’s paper is incorrect, as the black hole is not formed yet! Correct Hamiltonian was derived: H = p(r 2 – M)  ~ p(r 2 – H), which leads to a logarithmic, and not a power- law divergence in the action integral. Hence, there is no exponential suppression [PRD 66, (2002)] RSRS parton M 2 = s ^  ~  R S  ~ 1 TeV  ~ 10  m  ~ 100 pb

28 28December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Assumptions and Approximation Fundamental limitation: our lack of knowledge of quantum gravity effects close to the Planck scale Consequently, no attempts for partial improvement of the results, e.g.: Grey body factors BH spin, charge, color hair Relativistic effects and time-dependence The underlying assumptions rely on two simple qualitative properties: The absence of small couplings; The “democratic” nature of BH decays We expect these features to survive for light BH Use semi-classical approach strictly valid only for M BH » M P ; only consider M BH > M P Clearly, these are important limitations, but there is no way around them without the knowledge of QG

29 29December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Black Hole Production Schwarzschild radius is given by Argyres et al., hep-th/ [after Myers/Perry, Ann. Phys. 172 (1986) 304]; it leads to: Hadron colliders: use parton luminosity w/ MRSD- ’ PDF (valid up to the VLHC energies) Note: at c.o.m. energies ~1 TeV the dominant contribution is from qq ’ interactions  tot = 0.5 nb (M P = 2 TeV, n=7) LHC n=4  tot = 120 fb (M P = 6 TeV, n=3) [Dimopoulos, GL, PRL 87, (2001)]

30 30December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Black Hole Decay Hawking temperature: R S T H = (n+1)/4  (in natural units  = c = k = 1) BH radiates mainly on the brane [Emparan/Horowitz/Myers, hep- th/ ] ~ 2  /T H > R S ; hence, the BH is a point radiator, producing s-waves, which depends only on the radial component The decay into a particle on the brane and in the bulk is thus the same Since there are much more particles on the brane, than in the bulk, decay into gravitons is largely suppressed Democratic couplings to ~120 SM d.o.f. yield probability of Hawking evaporation into  l ±, and ~2%, 10%, and 5% respectively Averaging over the BB spectrum gives average multiplicity of decay products: Note that the formula for  N  is strictly valid only for  N  » 1 due to the kinematic cutoff E < M BH /2; If taken into account, it increases multiplicity at low  N  [Dimopoulos, GL, PRL 87, (2001)] Stefan’s law:  ~ s

31 31December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Black Hole Factory Drell-Yan  +X [Dimopoulos, GL, PRL 87, (2001)] Spectrum of BH produced at the LHC with subsequent decay into final states tagged with an electron or a photon n=2 n=7 Black-Hole Factory

32 32December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Shape of Gravity at the LHC Relationship between logT H and logM BH allows to find the number of ED, This result is independent of their shape! This approach drastically differs from analyzing other collider signatures and would constitute a “smoking cannon” signature for a TeV Planck scale [Dimopoulos, GL, PRL 87, (2001)]

33 33December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes Black Hole Events First studies already initiated by ATLAS and CMS ATLAS –CHARYBDIS HERWIG-based generator with more elaborated decay model [Harris/Richardson/Webber] CMS – TRUENOIR [GL] Simulated black hole event in the ATLAS detector [from ATLAS-Japan Group] Simulated black hole event in the CMS detector [A. de Roeck & S. Wynhoff]

34 34December 19, 2005Greg Landsberg - Out-of-this-World Physics: From Particles to Black HolesConclusions Stay tuned – next generation of collider experiments has a good chance to solve the mystery of large extra dimensions! If large extra dimensions are realized in nature, black hole production at future colliders is likely to be the first signature for quantum gravity at a TeV Many other exciting consequences from effects on precision measurements to detailed studies of quantum gravity If any of these new ideas is correct, we might see a true “Grand Unification” – that of particle physics, astrophysics and cosmology – in just a few years from now! If you still think that gravity is weak force, you may be spending too much time in the lab!


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