Prospettive future della fenomenologia delle particelle. Riccardo Barbieri IFAE Pavia 19/21 Aprile

Transcription

1 Prospettive future della fenomenologia delle particelle Riccardo Barbieri IFAE Pavia 19/21 Aprile

2 Particle Physics in one page L SM = 1 4 Fa µ!f aµ! + i "D" +! i " i j! j h + h.c. + D µ h 2 V (h) The gauge sector (1) The flavor sector (2) The EWSB sector (3) +N i M i j N j (if Majorana) The quadrant of nature whose laws can be summarized in one page with absolute precision and empirical adequacy Can it be the end of the story? The ν-mass sector (4) One century to develop it, from Maxwell on

3 Fundamental Physics defined (in absence of a better name) (NOT a naively reductionistic view, nor a definition of hierarchies in physics) Everything that fits in Page 1 by coherent addition or emendation, meeting the same or better standards of synthesis and empirical adequacy The central question: What will replace current Page 1?

4 The ambition and the complexity of the task require a multiform approach top-down What for the next page 1? side-wise bottom-up

5 top-down: The quantum numbers of the SM fermions (e.g. charge quantization) fit remarkably well in GUT schemes Experimental successes (not enough to make unification a fact) unification (+ supersymmetry) gauge unification (quantitative) neutrino masses (semi-quantitative) Further tests (both difficult and crucial) proton decay neutrino-less double-beta decay (only 3 light neutrinos)

6 Proton Decay Theory:! p B(p e + + " 0 ) = 1036±2 years Present knowledge (SK):! p B(p K + + ") =? years years Megaton Detector (x 10 years): years years Liquid Argon 100 kton (x 10 years): years years??? No free meal! Any synergy with neutrino detectors?

7 m ee =! i V 2 eim i neutrino-less double-beta decay m ee (ev ) (Fogli et al) (Strumia, Feruglio, Vissani) inverted normal Exp.s promise a few x 10 mev, significant but not enough! i m i (ev )

8 1. Aren t we seeing only two oscillation frequencies, after all? 2. What about the constraints from BBN, CMB, LSS? An illustrative case with 3 more N R (simple enough) L = g!v " µ ew µ +! T m d N + N T M d N 2 Standard deviations M 2 in ev log(m 3 /ev ) log(m 2 /ev ) Only 3 light Majorana neutrinos? Thermalized sterile Standard deviations M 3 in ev M 1 largely undetermined since m 1 0 (in general N T U T M d UN ) unknown Thermalized sterile B, Hall, Oliver, Strumia

9 bottom-up: The SM as the most general renormalizable theory with the given gauge symmetry and particle content the SM as a low energy approximation of a more complete theory L complete = L SM +!L Y =0 (" EWPT ) +!L Y 0 (" f lav ) 1. Why the Higgs boson in the low energy spectrum?! nat (400 GeV ) 115GeV 2. From the EWPT (LEP1 and LEP2)! EWPT 5 10 TeV 3. From the flavour tests! f lav 2 5 TeV m h The UT Collaboration all to be taken cum grano salis

10 A clash between these various Λ s? Supersymmetry theoretically most appealing! EWPT! nat OK Why no superpartner, no light Higgs, no flavour signal yet? Little Higgs, H = A 5, warped extrad, etc.! EWPT! nat still problematic Simple enough to be true? Strongly interacting Higgs! EWPT! nat? The perturbative success of the SM accidental?

11 The Standard Model again!m 2 h = " t # 2 t + " g # 2 g + " h # 2 h m h,gev Λ P,TeV Λ L,TeV ! t 3.5m h! g 9m h >! t! h 1.3 TeV U=0 m t = ± 2.9 GeV m h = GeV T 0 m h = GeV -0.2 m t m h 68 % CL

12 A simple (provisional) conclusion A Higgs boson in the mass range of GeV, if it were consistent with the EWPT, would allow to raise! nat to ~1.5 TeV without any cancellation and remaining fully perturbative! nat Can one raise? What allows to raise m h??! nat h

13 What allows to raise m h? Doubling the Higgs multiplet the simplest (?) solution, realized in several possible ways RB, Hall RB, Hall, Rychkov 1 TeV 500 GeV H ±,A,H h + possibly something else

14 Let the experiments decide LHC will explore for the first time the relevant energy range, well above the Fermi scale! QCD, G 1/2 F Flavour physics may give complementary information (although, without new extra degrees of freedom at the Fermi scale carrying flavour (family) indices, like superpartners, no need of a low! f lav )

15 The Flavour Sector 1 - We know the SM works quantitatively in the full quark sector (A major change in the 2000 s) 2 - If there are other degrees of freedom at the Fermi scale carrying flavour (s-fermions), unlikely that there be no extra flavour phenomena observable at some level 3 - We know all the 10 parameters in the quark sector (6+3+1) and 7 (3+2+2) out of the 10/12 ( /3) in the lepton sector (but no hard theory for them)

16 Testing Flavour Physics Qualitative, but highly significant: (finally in progress!?) BR(µ e +!) < d e (exp) = (0.07 ± 0.07)10 26 e cm µ B d neutron (exp) e cm e 2m N Quantitative: (highly interrelated) VV + = 1 Calculable Flavour Changing Neutral Current processes CP-asymmetries (A major change in the 2000 s)

17 The Flavor Precision Test (FPT) program (compare with the EWPT ) Genuine FCNC processes induced by a calculable loop Current status: Exp Th! K sd ds 1% 5-10% K +! + " " sd!! 70% 5%!m bd Bd db 1% 10% A CP (B d!k S ) bd db 5% <1% B d X s +! b s +! 10% 10% B d X s + l l b s + l l 20% 10%!m Bs Need to improve in precision, redundancy, new entries

18 B-physics: factories versus LHC Gino Isidori

19 Fully complementary info from K-physics ~ a dedicated experiment for every mode? Gino Isidori

20 side-wise Particle physics may not be the only way to address the question about page 1 particle physics astrophysics cosmology

21 Astro-particle Physics as a quite clear candidate, naturally related to Particle Physics in techniques and scope Dark Matter search (direct or indirect) High (and intermediate) energy gamma ray astronomy Gravity wave detection Low and high energy neutrino astrophysics High energy cosmic ray studies with priorities to be determined and technological milestones to be strictly implemented

22 Fra gli scopi specifici piu rilevanti: La natura della materia oscura? DM = WIMP M = GeV! m = O(1)! WIMP p pb La natura e l origine dei raggi cosmici E <!G N MR ev La mappa del cielo con sonde non deflettibili e non assorbibili Lo studio delle interazioni fra particelle ad energie/masse non accessibili agli acceleratori Lo studio della materia/energia in condizioni estreme

23 Conclusions No reason for the SM to be the end of the story LHC will explore for the first time the relevant energy range, well above the Fermi scale Need a multiform approach to go beyond the SM The best way to know the future of physics is to stay alive as much as possible (Freeman Dyson)