INTRODUZIONE. Shahram Rahatlou. Fisica delle Par,celle Elementari, Anno Accademico

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1 INTRODUZIONE Shahram Rahatlou Fisica delle Par,celle Elementari, Anno Accademico

2 ORARIO LEZIONI Lunedi` e Martedi` ore 16-18, Aula 7 Mercoledi` 14-16, Aula 8 Alcune settimane faremo 2 lezioni In totale ci saranno circa 25 lezioni Tutto il materiale e gli avvisi saranno disponibili sul sito web del corso 2

3 REFERENCE MATERIAL AND BOOKS Mostly using recent review papers and lectures at topical schools Some of the older topics and basics covered also in Burcham & Jobes: Nuclear and Particles Physics (Prentice-Hall) 3

4 MODALITA` D ESAME Non ci saranno presentazioni con le slide Prova orale con carta e penna Domande sul programma del corso non sui dettagli delle misure specifiche trattate nel corso ma sullo scopo e metodo degli esperimenti e della parte teorica/fenomenologica Potete portare una tesina come una domanda a scelta Saranno disponibili articoli di misure importanti riguardanti tutto il programma da approfondire come tesina Motivazione teorica e come la misura si colloca nello studio del Modello Standard o ricerca di nuova fisica Scelta dei rivelatori e vantaggi e svantaggi tecnica di misura i fondi principali e il motivo per cui sono fondi le incertezze sistematiche principali 4

5 SPECIAL YEAR: A NEW DISCOVERY FNS I & II? This Course! 5

6 STANDARD MODEL You are familiar with Electroweak symmetry breaking mechanism from Relativistic Quantum Mechanics Course We will discuss the phenomenology of this lagrangian 6

7 STANDARD MODEL BEFORE 4 TH JULY Will discuss this plot in LEP Precise limits on possible mass of Higgs from tests at LEP Stringent limits from direct searches at LHC in 2011 On 4th July 2012 we could have finally broken badly the Standard Model 7

8 FIRST DISCOVERY IN A VERY LONG TIME 17,000%% news%ar(cles%in% >"1"billion" people%saw%tv%footage% 108% countries%in% 2% days% 1,034" TV%sta.ons% 5,016" Broadcasts% 8

9 HIGGS IN THE NEWS 9

10 FIRST EVER SCALAR IN NATURE Heaviest boson so far in Nature! First scalar particle ever discovered Now testing whether the Higgs boson predicted in Standard Model so far no surprises 10

11 ROAD TO DISCOVERY Start with LEP crucial role with precision test of Standard Model Re-discovery of Standard Model with LHC new proton-proton machine Discovery of a new boson What else we expect to see at a hadron collider? 11

12 NEW BOSON AND OUR UNIVERSE 200 Instability Top mass Mt in GeV Meta-stability Stability Non-perturbativity Higgs mass M h in GeV Important implications of Higgs-like discovery Will discuss in this course what it means to be in a meta-stable universe Main question remains: have we discovered the SM Higgs or something else? 12

13 HIGGS AND CKM No more universal coupling constant! V ij Relative magnitudes d s b u c t 13

14 NEUTRINOS HAVE MASS! P (L) =sin 2 2 sin m2 (ev 2 )L(km) E(GeV m 2 13 O(GeV) O(1000km) O(MeV) O(1km) Pontecorvo m 2 12 O(MeV) m 2 13 O(GeV) O(1000km) O(MeV) O(1km) 2012 Beautiful measurement in 2012 T2K, Double Chooz Daya Bay, RENO 10% effect m f$ ~ λ# 14

15 evaluated for the 2011 dataset, modifying of expected combinatorial background in the s. The results for the B(s) 0! µ+ µ branchs have been updated accordingly. We ob- µ + µ ) < and B(B 0! µ + µ ) S/(S+B) Weighted Events / ( 0.04 GeV) OBSERVATION OF RARE SM EVENTS CMS - L = 5 fb s = 7 TeV, L = 20 fb s = 8 TeV at 95 % CL 14 to be compared to the published data full PDF! µ + µ ) < and B(B 0 0 B! s 12 µ+ µ µ + µ ) B µ + µ l bkg at 95 % CL [8], respectively. The combinatorial (1-CL bkg b ) bkg semileptonic bkg 0 10 peaking bkg 6 e with the systematic uncertainty previously 2 tasets are compatible within s! µ + µ changes from 18 % to 11 % and + µ branching fraction increases by ) 10 9 to ( ) This shift the background shape [8]. The values of the 4 branching fraction obtained with the 2011 ination of all categories used in the categorized-bdt atasets, (right). For respectively. these plots, the The individual parameters categories that are ) is the signal (background) determined at the B 0 s peak 1 ed 100 % D0 correlated 10.4fb between the two datasets set such that the fitted B 0 s signal corresponds to the total hese (B + distributions! J/ K + are ) for andillustrative B(B 0! purposes K + only ), the 1 CDF 10fb and sults. oint of the Crystal Ball function describing 1-1 and 2012 results 0 are combined by computing performing References the maximum-likelihood m µµ (GeV) fit siy to the eight and seven BDT bins of the 2011 µ + [MeV/c 2 3 m ] µ ATLAS 4.9fb SM s background and SM signal were observed. The shaded yellow area covers, for each branching fraction value, 34 % of the expected CL s distribution on each side of its median. The solid red curve is the observed CL s ass lineshape, preliminary the mass distribution of the 0 1 background, LHCb 3fb the BDT and mass distrihe B 0! µ + µ and B 0(+)! 0(+) µ + 1 CMS 25fb µ and the SM predictions of the Bs 0! µ + µ CMS+LHCb + CMS+LHCb preliminary preliminary µ branching fractions. The distribution of dashed) and observed events in bins of BDT in 0the 9 B(Bs µ µ ) [10 ] B(B µ + µ ) [10 ] s obtained from the simultaneous analysis of Shahram Figure Rahatlou, 2: Comparison Roma Sapienza & INFN of previous results [7 9], the latest CMS and LHCb results [11, 12], the com- Candidates / (50 MeV/c 2 ) Summer fb 1 (7TeV) +1.1 fb LHCb 1 (8TeV) BDT > FIG. 2. CDF Invariant 10fb mass distribution of the SM selected Bs 0! µ + µ candidates (black dots) with BDT > 0.7 inthecombined LHCb 3fb dataset. The result of the fit is overlaid (blue solid line) and the di erent components detailed: Bs 0! µ + µ (red long dashed), B 0! µ + µ (green medium dashed), B 0 1 CMS 25fb (s)! h + h 0 (pink dotted), B 0! µ + µ (black short dashed) and B 0(+)! 0(+) µ + µ (light blue dot dashed), and the combinatorial background (blue medium 15

16 SOME QUESTIONS COVERED IN THIS COURSE Hierarchy problem and fine tuning Is there really supersymmetry in Nature and if so where are the new particles? Are there new forces and particles? What about extra spatial dimensions and black holes? Where does the neutrino mass come from? What is Dark Matter and how to search for it? 16

17 TENTATIVE COURSE PLAN Brief review of deep inelastic scattering (2h) LEP precision measurements (4h) LHC vs LEP: challenges of pp collisions (2h) Standard Model at LHC: W, Z, top (6h) Higgs searches: LHC (8h) Supersymmetry: introduction. Search strategy (4h) Exotics physics: new forces, extra dimensions, 4th generation, black holes and more (4h) CP Violation and B physics (6h) Neutrinos: oscillations and search for double beta decay (6h) Lepton Flavor Violation (4h) Dark matter and LHC (2h) 17