Gravity and Particle Physics at Different Scales by Gia Dvali : Brief review of Max-Planck-Institute for Physics Cosmology/Astro-Particle & Beyond the Standard Model physics research.

Physics at cm: Understanding fundamental physics behind the stability of weak interaction scale: Role of gravity; Supersymmetric Higgs as a pseudo-Goldstone boson (sound-wave); What is the connection between gravity and particle species? Species = Geometry? Implications for LHC: Micro black holes; String Resonances; Extra Dimensions; …

Fundamental Physics at cm: What is the reason behind the accelerated expansion of the Universe? Self-acceleration? Is graviton truly massless? Is it even consistent to change gravity at large distances? Why can’t extra dimensions manifest themselves at large as opposed to small distances? What are the observational consequences of this approach? Is the vacuum energy de-gravitated because of graviton mass?

Physics in very early Universe: Inflation in String Theory: Brane Inflation? Big-Bang from annihilating D-branes? Understanding String Theoretic cosmology in terms of effective field theory: Brane inflation = Supersymmetric D-term inflation Cosmic Strings as fundamental superstrings?

THE SEARCHES OF THE NEW (BEYOND THE STANDARD MODEL) PHYSICS AT THE LARGE HADRON COLLIDER ARE (Mainly) MOTIVATED BY THE HIERARCHY PROBLEM, AN INEXPLICABLE STABILITY OF THE WEAK INTERACTION SCALE (M W = 10 2 GeV) VERSUS THE PLANCK MASS (M P = GeV), WHY IS M 2 W /M 2 P = ?

10 12 LL THE HIERARCHY PROBLEM IS NOT ABOUT BIG/SMALL NUMBERS! THERE ARE PLENTY OF BIG/SMALL NUMBERS IN NATURE THAT ARE OF NO MYSTERY. ELEPHANTS (OR HUMANS) ARE BIG, BECAUSE THEY CARRY A HUGE BARYON NUMBER.

THE HIERARCHY PROBLEM IS ABOUT THE UV STABILITY OF THE VERY SMALL NUMBER M 2 W /M 2 P =

STANADARD MODEL GAUGE FORCES: SU(3)xSU(2)xU(1) MATTER: QUARKS : (u,d) (c,s) (t,b), LEPTONS: (e,ν e ) (μ, ν μ ) (τ, ν τ ) HIGGS: H The weak scale is set by the vacuum expectation value of the Higgs field, which is related to the mass of the Higgs boson, m H. This mass is UV-unstable!

H H t t H H H + UV-instability of the Higgs mass δm 2 H ≈ Λ 2 ! + The natural cutoff is the gravity scale Λ = M P

Without gravity one could have said that the problem is not so severe: After all, the theory must have a scale and it happens to be around 100GeV. But with gravity there is a very little flexibility. In Einstein’s gravity M P is the scale where gravitational interactions of elementary particles become strong. In any sensible theory of gravity, which at large distances reduces to Einstein’s GR, a point-like elementary particle heavier than M P makes no sense.

In fact we know very well what such an object is: Because its gravitational Schwarzschild radius exceeds its Compton wavelength, R = m/M 2 P > 1/m, it is a macroscopic classical black hole! And becomes more and more classical with the growing mass. R

Without gravity the problem could have been less severe, but with gravity there is no way out: The particles running in the loop cannot have arbitrarily high energies without becoming big black holes! HH

’98 Quantum Gravity at TeV Idea: Weak scale is stable, because the quantum gravity scale M * ≈ TeV ! (Arkani-Hamed, Dimopoulos, GD; Antoniadis, Arkani-Hamed, Dimopoulos, GD) But, if gravity becomes strong around the TeV scale, why is the large distance gravity so much weaker than all the other forces of nature? For example, gravitational attraction between the two protons at 1 m distance is times weaker of their Coulomb repulsion! Original Realization: Extra Dimensions

As a result of the dilution, there is a simple relation between the true quantum gravity scale and the Planck mass measured at large distances: M 2 P = M 2 * (M * R) n Volume of extra space

The Role of Particle Species in Lowering Gravity Scale. M 2 P = M 2 * (M * R) n Volume of extra space We can now understand the geometric relations in terms of particle species number counting, M 2 P = M 2 * N, Where N is the number of species. This very important, because the latter expression turns out to be more general than the former: What matters is the number of species!

Hawking flux of N species with T = 1/R The black holes of size R < L * = √N / M P cannot afford to be semi-classical, because they half-evaporate Faster than their size! Equivalently, the rate of temperature-change is faster than the temperature-squared dT/dt > T 2

Thus, the fundamental length scale below which no semi-classical black holes can exist in any consistent theory with N species is L * = √N / M P and the corresponding mass scale marks the cutoff. M 2 * = M 2 P /N

Message encoded in a green flavor Pixel of size L, with all the sample flavors

M -1 P √N/M P R mr g m -1 Strength of Gravity as Function of Distance

The black hole arguments show, that the class of theories which solve the Hierarchy Problem by TeV quantum gravity scale, is much larger. In particular, any theory with N = particle species, will do this. The role of these species, can equally well be played by Kaluza-Klein gravitons from large extra dimensions, or by copies of the Standard Model!

Einsteinian Black Holes carry no hair Such Black Holes can only be distinguished by exactly conserved quantum numbers measurable at infinity. For example, such numbers are the mass of a Black Hole and its electric charge. On the other hand, quark and lepton flavors in the Standard Model are not exactly-conserved quantum numbers of nature, and are impossible to measure outside the Black Hole horizon.

Flavor -violation by Black Holes can be visualized by the following thought experiment. In Standard Model we can produce a large classical black hole by colliding particles of a given flavor, e.g., electron-positron. If the Hawking Temperature of this Black Hole is sufficiently high, it will evaporate in all three lepton generations (and in other possible species) fully democratically, e + + e - e-e- e+e+ μ-μ- τ+τ+ Thus, macroscopic Black Holes violate flavor maximally. Everything possible

What about the microscopic Black Holes that may be produced at LHC? It turns out that story for them is different: The small black holes must carry memory about their origin, and are non-democratic!

In particular, for center of mass energies E > M db = M * (M * R db ) n+1, d-b transition processes become order one. d d s b The number of quanta emitted N final = (E/M * ) (n+2)/(n+1)

Hawking flux of species in string theory Naively there are exponentially growing number of species, so that the black holes smaller than R < L S cannot afford to be semi-classical. But, this is not true. The effective number of species to which black holes evaporate turns out to be bounded by: N EFF = 1/g S 2 ! GD & Lüst ; GD & Gomez

Experimental signatures of low scale quantum gravity are pretty spectacular. These include formation of mini black holes, Kaluza-Klein gravitons, and string vibrations in particle collisions (e.g., high spin recurrences of ordinary particles). (For a recent detailed study of string production within type II strings see work by, Lust, Stieberger, Taylor;... )

Gravitational shortcut

STRING THEORY PICTURE open strings closed strings ordinary particles gravity

This is an exciting time for the particle physics community. LHC will directly probe the mechanism which is responsible for generating the weak interaction scale and masses of the elementary particles. And, there is a strong theoretical indication, that LHC will also probe physics that is behind the stability of the above scale. If the ideas presented in this talk have anything to do with nature, LHC has an exceptional chance of experimentally discovering and studying the nature of quantum gravity.

Universe’s acceleration: Friedmann equation (flat universe) Dark energy or Modified Gravity? Hubble parameter:

Large distance modification of gravity at the fundamental level Implies that graviton is not exactly massless. Equivalently, in geometric terms this can be understood as extra dimensions showing-up at cosmological distances, so that gravitational flux spreads out Into the extra space. This spread-out from observational point of view would manifest itself as: 1) Change of expansion law, that can be tested by cosmological observations; 2) As anomalous correction to planetary motions; For example Anomalous precession of the lunar orbit  =1.4 x ) As observable modification to the spectrum of density perturbations.

FRW Equation is modified H 2 - H/r c =  Early cosmology in normal H>>r c -1 Late cosmology H  H = r c -1 At late times Universe is self-accelerating! NO NEED IN DARK ENERGY?

LUNAR RANGING TEST OF MODIFIED GRAVITY Predicted anomalous perihelion precession of the lunar orbit  =1.4 x Todays accuracy:   =2.4 x fold improvement is expected

Members: Group leader: Stefan Antusch Postdocs: – Lorenzo Calibbi – Yu Min Kim – Toshihiko Ota – Enrique Fernandez-Martinez (since 10/10 → CERN) – Koushik Dutta (since 10/10 → DESY) Phd students: – Jochen Baumann – Sebastian Halter – Philipp Kostka – Martin Spinrath (since 10/10 → SISSA) Diploma students: – Valerie Domcke – Vinzenz Maurer Max Planck Research Group: Beyond the Standard Model Group started 9/2007

Max Planck Research Group: Beyond the Standard Model Neutrino Physics Unified Theories & Flavour Physics Early Universe Cosmology Origin of neutrino mass? Origin of large lepton mixing? (Non-)unitarity of U PMNS ? Inflation in particle physics theories? Matter-antimatter asymmetry? Dark matter? Origin of structure? Unification of forces? Origin of flavour structure? Flavour in supersymmetry? Research:

Selected Scientific Highlights: Neutrino Physics: Theory and bounds for non-unitary lepton mixing matrix U PMNS Bounds on gauge invariant new interactions in the lepton sector Unified Theories & Flavour Physics: Predictive flavour structure (SM+SUSY) from family symmetries New GUT predictions for quark and lepton mass ratios → Poster Early Universe Cosmology: New inflaton candidate: Unified matter superparticle in SUSY GUTs New models of inflation in supergravity (e.g. with Heisenberg symmetry) → Poster Max Planck Research Group: Beyond the Standard Model

A stroparticle Theory B eyond the Standard Model C osmology Strong synergy with Stefan Antusch’s Independent MPG Junior Research Group (Collaborative projects & common Thursday seminar) Senior staff Georg Raffelt Frank Steffen (also IMPRS coordinator) Leo Stodolsky (director emeritus) Postdocs & Fellows Mattias Blennow (Marie Curie fellow) Javier Redondo Shun Zhou (AvH fellow) Christoph Weniger Ph.D. Students Davide Cadamuro Peter Graf Jonas Lindert David de Sousa Seixas Recent departures Carla Biggio  U Barcelona Basudeb Dasgupta  Ohio State Josef Pradler  Perimeter Alessandro Mirizzi  Junior Prof. U Hamburg Yvonne Y.Y. Wong  Junior Prof. RWTH Aachen Pasquale Di Bari  Lecturer, Southampton Recent exchange students Irene Tamborra (U Bari, Italy) Tina Lund (U Aarhus, Denmark) Amol Patwardhan (Mumbai, India)

Networking & Collaborations Origin and Structure of the Universe The Cluster of Excellence for Fundamental Physics TUM, LMU, MPP, MPA, MPE, ESO International School on AstroParticle Physics (30+ Institutes) U Bari, Ferrara, Genova, Milano, Milano Bicocca, Napoli, Padova, Roma Vergata, Torino & LNGS, TUM, MPP, U Heidelberg, MPIK, U & FZ Karlsruhe, APC & Orsay, Weizmann, U Aarhus, Trondheim, Stockholm, INR & Kurchatov, U Valencia, Santiago de Compostela, Autonoma Madrid, … Max Planck India Partnergroup (until 12/2009) Neutrino Physics and Astrophysics Amol Dighe (MPP alumnus) and his group at Tata Institute of Fundamental Research (TIFR), Bombay, India Transregional Collaborative Research Centre TR 27 Neutrinos and Beyond Weakly Interacting Particles in Physics, Astrophysics & Cosmology TUM, MPP, MPA, KIT (Karlsruhe), U Tübingen, MPIK (Heidelberg) CAST Experiment Astroparticle Physics

Research Topics Dark matter particles (WIMP-like & SUSY) - Early-universe production - Collider signatures, BBN impact - Detection (indirect & CRESST) Axions and similar particles - Experimental searches (CAST, ALPS) - Photon conversion in lab & astro B fields - Primordial production, cosmo limits Neutrinos & axions in cosmology - Mass limits from precision data - Extra radiation, flavor oscillations, BBN - Leptogenesis Supernova neutrinos - Collective flavor oscillations - Experimental signatures from next SN - Sterile neutrino production Neutrino phenomenology & BSM - Experimental signatures at LBL expts - MonteCubes software - Models, non-standard interactions Frank Steffen Christoph Weniger Mattias Blennow Leo Stodolsky Javier Redondo Georg Raffelt Frank Steffen, students (A.Mirizzi until 2009) Georg Raffelt (previously Di Bari, Wong) Students Georg Raffelt, Shun Zhou (B. Dasgupta, A. Mirizzi until 2009/10) Students Mattias Blennow Shun Zhou (Carla Biggio until 2010) with Antusch group