SUSY AND ASTROPARTICLE PHYSICS

1. X ROMA3 TOPICAL SEMINAR ON SUBNUCLEAR PHYSICS: SUSY TODAY: TH. AND EXP. LIMITS ONE YEAR BEFORE LHC, Univ. ROMA TRE, DEC. 13, 2007 SUSY ANDASTROPARTICLE PHYSICS Antonio Masiero Univ. di Padova INFN, Padova

2. UNIFICATION ofFUNDAMENTAL INTERACTIONS

3. THE G-W-S STANDARD MODEL

4. The HIGGS BOSON CONDENSATE • “SOMETHING” fills the Universe: it “disturbs” Weak interactions making them SHORT-RANGED, while it does NOT affect gravity or electromagnetism. • WHAT IS IT? • Analogy with SUPERCONDUCTIVITY: in a superconductor the magnetic field gets repelled ( Meissner effect) and penetrates only over the “penetration length”, i.e. the magnetic field is short-ranged source which disturbs are the boson condensates, Cooper pairs. • We are “swimming” in Higgs Boson Condensates its value at the minimum of its potential determines the masses of all particles!

5. Where all masses come from: the HIGGS mechanism THE HIGGS MECHANISM CAN BE REALIZED BY THE PRESENCE OF AN ELEMENTARY HIGGS PARTICLE The Higgs has already “shown up” as a VIRTUAL particle in electroweak radiative effects

6. MICRO MACRO PARTICLE PHYSICS COSMOLOGY HOT BIG BANG STANDARD MODEL GWS STANDARD MODEL HAPPY MARRIAGE Ex: NUCLEOSYNTHESIS POINTS OF FRICTION BUT ALSO • COSMIC MATTER-ANTIMATTER ASYMMETRY • INFLATION • - DARK MATTER + DARK ENERGY “OBSERVATIONAL” EVIDENCE FOR NEW PHYSICS BEYOND THE (PARTICLE PHYSICS) STANDARD MODEL

7. THE ENERGY BUDGET OF THE UNIVERSE (as of Dec. 2007)

8. DM: the most impressive evidence at the “quantitative” and “qualitative” levels of New Physics beyond SM • QUANTITATIVE: Taking into account the latest WMAP data which in combination with LSS data provide stringent bounds on DM and BEVIDENCE FOR NON-BARYONIC DM AT MORE THAN 10 STANDARD DEVIATIONS!!THE SM DOES NOT PROVIDE ANY CANDIDATE FOR SUCH NON-BARYONIC DM • QUALITATIVE: it is NOT enough to provide a mass to neutrinos to obtain a valid DM candidate; LSS formation requires DM to be COLD NEW PARTICLES NOT INCLUDED IN THE SPECTRUM OF THE FUNDAMENTAL BUILDING BLOCKS OF THE SM !

9. THE RISE AND FALL OF NEUTRINOS AS DARK MATTER • Massive neutrinos: only candidates in the SM to account for DM. From here the “prejudice” of neutrinos of a few eV to correctly account for DM • Neutrinos decouple at ~1 MeV ; being their mass<<decoupling temperature, neutrinos remain relativistic for a long time. Being very fast, they smooth out any possible growth of density fluctuation forbidding the formation of proto-structures. • The “weight” of neutrinos in the DM budget is severely limited by the observations disfavoring scenarios where first superlarge structures arise and then galaxies originate from their fragmentation

10. m = 0 eV m = 1 eV (E..g., Ma 1996) m = 7 eV m = 4 eV LSS PATTERN AND NEUTRINO MASSES

11. Cosmological Bounds on the sum of the masses of the 3 neutrinos from increasingly rich samples of data sets

12. WIMPS (Weakly Interacting Massive Particles) # exp(-m/T) # does not change any more #~# m  Tdecoupl. typically ~ m /20    depends on particle physics (annih.) and “cosmological” quantities (H, T0, … 10-3  h2_ ~ <(annih.) V  > TeV2 From T0 Mplaeli ~ 2 / M2 h2 in the range 10-2 -10-1 to be cosmologically interesting (for DM) m ~ 102 -103 GeV (weak interaction) h2 ~ 10-2 -10-1 !!!

13. THE COSMIC MATTER-ANTIMATTER ASYMMETRY PUZZLE:-why only baryons -why Nbaryons/Nphoton ~ 10-10 • NO EVIDENCE OF ANTIMATTER WITHIN THE SOLAR SYSTEM • ANTIPROTONS IN COSMIC RAYS: IN AGREEMENT WITH PRODUCTION AS SECONDARIES IN COLLISIONS • IF IN CLUSTER OF GALAXIES WE HAD AN ADMIXTURE OF GALAXIES MADE OF MATTER AND ANTIMATTER THE PHOTON FLUX PRODUCED BY MATTER-ANTIMATTER ANNIHILATION IN THE CLUSTER WOULD EXCEED THE OBSERVED GAMMA FLUX • IF Nba . = Nantibar AND NO SEPARATION WELL BEFORE THEY DECOUPLE . WE WOULD BE LEFT WITH Nbar./Nphoton << 10-10 • IF BARYONS-ANTIBARYONS ARE SEPARATED EARLIER DOMAINS OF BARYONS AND ANTIBARYONS ARE TOO SMALL SMALL TODAY TO EXPLAIN SEPARATIONS LARGER THAN THE SUPERCLUSTER SIZE ONLY MATTER IS PRESENT HOW TO DYNAMICALLY PRODUCE A BARYON-ANTIBARYON ASYMMETRY STARTING FROM A SYMMETRIC SITUATION

14. COSMIC MATTER-ANTIMATTER ASYMMETRY Murayama

15. SM FAILS TO GIVE RISE TO A SUITABLE COSMIC MATTER-ANTIMATTER ASYMMETRY • SM DOES NOT SATISFY AT LEAST TWO OF THE THREE SACHAROV’S NECESSARY CONDITIONS FOR A DYNAMICAL BARYOGENESIS: • NOT ENOUGH CP VIOLATION IN THE SM NEED FOR NEW SOURCES OF CPV IN ADDITION TO THE PHASE PRESENT IN THE CKM MIXING MATRIX • FOR MHIGGS > 80 GeV THE ELW. PHASE TRANSITION OF THE SM IS A SMOOTH CROSSOVER NEED NEW PHYSICS BEYOND SM. IN PARTICULAR, FASCINATING POSSIBILITY: THE ENTIRE MATTER IN THE UNIVERSE ORIGINATES FROM THE SAME MECHANISM RESPONSIBLE FOR THE EXTREME SMALLNESS OF NEUTRINO MASSES

16. MATTER-ANTIMATTER ASYMMETRY NEUTRINO MASSES CONNECTION: BARYOGENESIS THROUGH LEPTOGENESIS • Key-ingredient of the SEE-SAW mechanism for neutrino masses: large Majorana mass for RIGHT-HANDED neutrino • In the early Universe the heavy RH neutrino decays with Lepton Number violatiion; if these decays are accompanied by a new source of CP violation in the leptonic sector, then it is possible to create a lepton-antilepton asymmetry at the moment RH neutrinos decay. Since SM interactions preserve Baryon and Lepton numbers at all orders in perturbation theory, but violate them at the quantum level, such LEPTON ASYMMETRY can be converted by these purely quantum effects into a BARYON-ANTIBARYON ASYMMETRY ( Fukugita-Yanagida mechanism for leptogenesis )

17. INFLATION • CAUSALITY (isotropy of CMBR) • FLATNESS ( close to 1 today) • AGE OF THE UNIV. • PRIMORDIAL MONOPOLES SEVERE COSMOGICAL PROBLEMS COMMON SOLUTION FOR THESE PROBLEMS VERY FAST (EXPONENTIAL) EXPANSION IN THE UNIV.  V() VACUUM ENERGY  dominated by vacuum en. TRUE VACUUM NO WAY TO GET AN “INFLATIONARY SCALAR POTENTIAL” IN THE STANDARD MODEL

18. NO ROOM IN THE PARTICLE PHYSICS STANDARD MODEL FOR INFLATION V=2 2 + 4 no inflation Need to extend the SM scalar potential Ex: GUT’s, SUSY GUT’s,… ENERGY SCALE OF “INFLATIONARY PHYSICS”: LIKELY TO BE » Mw DIFFICULT BUT NOT IMPOSSIBLE TO OBTAINELECTROWEAK INFLATION IN SM EXTENSIONS

19. WHY TO GO BEYOND THE SM “OBSERVATIONAL” REASONS THEORETICAL REASONS • INTRINSIC INCONSISTENCY OF SM AS QFT • (spont. broken gauge theory • without anomalies) • NO ANSWER TO QUESTIONS THAT “WE” CONSIDER “FUNDAMENTAL” QUESTIONS TO BE ANSWERED BY “FUNDAMENTAL” THEORY • (hierarchy, unification, flavor) • HIGH ENERGY PHYSICS • (but AFB……) • FCNC, CP • NO (but b sqq penguin …) • HIGH PRECISION LOW-EN. • NO (but (g-2) …) • NEUTRINO PHYSICS • YE m0, 0 • COSMO - PARTICLE PHYSICS • YE (DM, ∆B cosm, INFLAT., DE) Z bb NO NO NO NO YES YES YES

20. Fundamental COUPLING CONSTANTS are NOT CONSTANT

21. LOW-ENERGY SUSY AND UNIFICATION

22. “MASS PROTECTION” ForFERMIONS, VECTOR (GAUGE) and SCALAR BOSONS • FERMIONS chiral symmetry • fL fR not invariant • under SU(2)x U(1) SIMMETRY PROTECTION -VECTOR BOSONS gauge symmetry FERMIONS and W,Z VECTOR BOSONS can get a mass only when the elw. symmetry is broken mf, mw ≤ <H> NO SYMMETRY PROTECTION FOR SCALAR MASSES “INDUCED MASS PROTECTION” Create a symmetry (SUPERSIMMETRY) Such that FERMIONS BOSONS So that the fermion mass “protection” acts also on bosons as long as SUSY is exact SUSY BREAKING ~ SCALE OF 0 (102-103 Gev) LOW ENERGY SUSY

23. ON THE RADIATIVE CORRECTIONS TO THE SCALAR MASSES

24. DESTABILIZATION OF THE ELW. SYMMETRY BREAKING SCALE SCALAR MASSES ARE “UNPROTECTED” AGAINST LARGE CORRECTIONS WHICH TEND TO PUSH THEM UP TO THE LARGEST ENERGY SCALE PRESENT IN THE FULL THEORY EX:

25. The Energy Scale from the“Observational” New Physics neutrino masses dark matter baryogenesis inflation NO NEED FOR THE NP SCALE TO BE CLOSE TO THE ELW. SCALE The Energy Scale from the “Theoretical” New Physics Stabilization of the electroweak symmetry breaking at MW calls for an ULTRAVIOLET COMPLETION of the SM already at the TeV scale+ CORRECT GRAND UNIFICATION “CALLS” FOR NEW PARTICLES AT THE ELW. SCALE

26. IS THE FINE-TUNING A REAL PROBLEM? • WARNING: THERE EXISTS AN EVEN “LARGER” HIERARCHY OR FINE -TUNING OR NATURALNESS PROBLEM: THE COSMOLOGICAL CONSTANT PROBLEM (“ THE MOTHER” OF ALL NATURALNESS PROBLEMS); SO FAR, WE SIMPLY “ACCEPT” SUCH FINE-TUNING! • (OUTRAGEOUS) POSSIBILITY: THE “THEORY OF EVERYTHING” COULD BE UNIQUE, BUT WITH MANY (INFINITE?) VACUA EACH GIVING RISE TO A DIFFERENT UNI-VERSE ( MULTI-VERSE POSSIBILITY).WE CAN LIVE ONLY IN THE VERY RESTRICTED CLASS OF THE “MULTI-VERSE SPACE” WHERE THE “BOUDARY CONDITIONS” ( FOR INSTANCE, THE VALUE OF THE COSMOLOGICAL CONSTANT OR THE SCALE OF THE ELW.SYMMETRY BREAKING AND, HENCE, THE HIGGS MASS) EXHIBIT VALUES ALLOWING FOR THE CORRECT BBN, LSS,… OUR LIFE! ANTHROPIC PRINCIPLE

27. HOW TO COPE WITH THE HIERARCHY PROBLEM • LOW-ENERGY SUSY • LARGE EXTRA DIMENSIONS • DYNAMICAL SYMMETRY BREAKING OF THE ELW. SYMMETRY • LANDSCAPE APPROACH (ANTHROPIC PRINCIPLE)

28. ROADS TO GO BEYOND THE STANDARD MODEL (I) 1) THERE EXISTS NO NEW PHYSICAL ENERGY SCALE ABOVE THE ELW. SCALE: gravity is an extremely weak force not because of the enormous value of the Planck scale, but because of the existence of NEW DIMENSIONS beyond the usual 3+1 space-time where (most of) the gravity flux lines get “dispersed” VISIBILITY AT LHC: there exist “excited” states of the ordinary particles ( Kaluza-Klein states) and some of them are accessible at LHC (the lightest KK state may be a stable particle and it can constitute the DM)

29. ROADS TO GO BEYOND THE STANDARD MODEL (II) • 2)NO NEED TO “PROTECT” THE HIGGS MASS AT THE ELW. SCALE: THE HIGGS IS A COMPOSITE OBJECT (for instance, a fermion condensate) WHOSE COMPOSITENESS SCALE IS THE ELW. SCALE (cfr. the pion mass case) VISIBILITY AT LHC: THERE EXIST NEW (STRONG) INTERACTIONS AT THE ELW. SCALE WHICH PRODUCE THE HIGGS CONDENSATE ( new resonances,, new bound states, a new rescaled QCD at 1 TeV)

30. ROADS TO GO BEYOND THE STANDARD MODEL (III) • 3) THE MASS OF THE ELEMENTARY HIGGS BOSON IS “PROTECTED” AT THE ELW. SCALE BECAUSE OF THE PRESENCE AT THAT ENERGY OF A NEW SYMMETRY, THE SUPERSYMMETRY (SUSY) VISIBILITY AT LHC: WE’LL SEE (SOME OF) THE SUSY PARTICLES AND THEIR INTERACTIONS. THE LIGHTEST SUSY PARTCILE (LSP) IS LIKELY TO BE STABLE AND PROVIDE THE DM. AT THE SAME TIME, WE COULD DISCOVER SUSY AND THE SOURCE OF 90% OF THE ENTIRRE MATTER PRESENT IN THE UNIVERSE.

31. HIERARCHY PROBLEM: THE SUSY WAY SUSY HAS TO BE BROKEN AT A SCALE CLOSE TO 1TeV LOW ENERGY SUSY m2 2 Scale of susy breaking F B f f B F   Sm2  ~( B - 2f )2 16 2 [m2 B - m2F ]1/2 ~ 1/√GF B In SUSY multiplet F SPLITTING IN MASS BETWEEN B and F of O ( ELW. SCALE)

32. THE SUSY PATH

33. LOW-ENERGY SUSY

34. IS SUSY PRESENT IN NATURE? • I think that it is very likely that SUSY is present as a fundamental symmetry of Nature: it is the most general symmetry compatible with a good and honest QFT, it is likely to be needed to have a consistent STRING theory ( super-string), in its local version ( local supersymmetry or supergravity) it paves the way to introduce and quantize GRAVITY in a unified picture of ALL FUNDAMENTAL INTERACTIONS • Much more debatable is whether it should be a LOW-ENERGY SYMMETRY ( i.e. effectively broken at the elw. Scale) or a HIGH-ENERGY SYMMETRY (i.e. broken at the Planck scale, or at the string compactification scale)

35. D. KAZAKOV

37. IN SUSY WE NEED TO INTRODUCE AT LEAST TWO HIGGS DOUBLETS IN ORDER TO PROVIDE A MASS FOR BOTH THE UP- AND DOWN- QUARKS

38. BREAKING SUSY • The world is clearly not supersymmetric: for instance, we have not seen a scalar of Q=1 and a mass of ½ MeV, i.e. the selectron has to be heavier than the electron and, hence, SUSU has to be broken SUSY HAS TO BE BROKEN AT A SCALE > 100 GeV SINCE NO SUSY PARTNERS HAVE BEEN SEEN UP TO THOSE ENERGIES, roughly COLORED S-PARTICLE MASSES > 200 GeV UNCOLORED S- PARTICLE MASSES > 100 GeV

39. WHICH SUSY HIDDEN SECTOR SUSY BREAKING AT SCALE F F = (105 - 106) GeV F = MW MPl GRAVITY GAUGE INTERACTIONS MESSENGERS Mgravitino ~ F/MPl ~ (102 -103)eV Mgravitino ~ F/MPl ~ (102 -103) GeV OBSERVABLE SECTOR SM + superpartners MSSM : minimal content of superfields

40. THE SOFT BREAKING TERMS OF THE MINIMAL SUSY SM (MSSM)

41. THE FATE OF B AND L IN THE SM AND MSSM • IN THE SM B AND L ARE “AUTOMATIC” SYMMETRIES: NO B or L VIOLATING OPERATOR OF DIM.≤4 INVARIANT UNDER THE GAUGE SIMMETRY SU(3) X SU(2) X U(1) IS ALLOWED ( B AND L ARE CONSERVED AT ANY ORDER IN PERTURBATION THEORY, BUT ARE VIOLATED AT THE QUANTUM LEVEL (ONLY B – L IS EXACTLY PRESERVED ) • IN THE MSSM, THANKS TO THE EXTENDED PARTICLE SPECTRUM WITH NEW SUSY PARTNERS CARRYING B AND L, IT IS POSSIBLE TO WRITE ( RENORMALIZABLE) OPERATORS WHICH VIOLATE EITHER B OR L • IF BOTH B AND L VIOLATING OPERATORS ARE PRESENT, GIVEN THAT SUSY PARTNER MASSES ARE OF O(TEV), THERE IS NO WAY TO PREVENT A TOO FAST PROTON DECAY UNLESS THE YUKAWA COUPLINGS ARE INCREDIBLY SMALL!

42. D. kAZAKOV

43. ADDITIONAL DISCRETE SYMMETRY IN THE MSSM TO SLOW DOWN P - DECAY • SIMPLEST (and nicest) SOLUTION: ADD A SYMMETRY WHICH FORBIDS ALL B AND L VIOLATING OPERATORS R PARITY • SINCE B AND L 4-DIM. OPERATORS INVOLVE 2 ORDINARY FERMIONS AND A SUSY SCALAR PARTICLE, THE SIMPLEST WAY TO ELIMINATE ALL OF THEM: R = +1 FOR ORDINARY PARTICLES R = - 1 FOR SUSY PARTNERS IMPLICATIONS OF IMPOSING R PARITY: i) The superpartners are created or destroyed in pairs; ii) THE LIGHTEST SUPERPARTNER IS ABSOLUTELY STABLE

44. BROKEN R PARITY • PROTON DECAY REQUIRES THE VIOLATION OF BOTH B AND L NOT NECESSARY TO HAVE R PARITY TO KILL B AND L VIOLATING OPERATORS ENOUGH TO IMPOSE AN ADDITIONAL DISCRETE SYMMETRY TO FORBID EITHER B OR L VIOLATING OPERATORS; RESTRICTIONS ON THE YUKAWA COUPLINGS OF THE SURVIVING B OR L VIOLATING OPERATORS

45. 124 FREE PARAM. D. KAZAKOV

46. CMSSM + RADIATIVE ELW. BREAKING: A 4 – PARAMETER WORLD • FREE PARAM. IN THE CMSSM : IMPOSING THE RAD. BREAKING OF THE ELW. SYMMETRY ONE ESTABLISHES A RELATION BETWEEN THE ELW. BREAKING SCALE AND THE SOFT SUSY PARAMETERS FURTHER REDUCING THE NUMBER OF THE FREE PARAM. IN THE CMSSM TO FOUR , FOR INSTANCE THE FIRST FOUR PARAM. ABOVE + THE SIGN OF µ ( THE ELW. SYMM. BREAKING FIXES ONLY THE SQUARE OF µ

47. D. KAZAKOV