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B A B AR : Prospettive future Riunione di Commissione 1 Assisi, 20 settembre 2004 Francesco Forti INFN-Pisa.

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Presentazione sul tema: "B A B AR : Prospettive future Riunione di Commissione 1 Assisi, 20 settembre 2004 Francesco Forti INFN-Pisa."— Transcript della presentazione:

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2 B A B AR : Prospettive future Riunione di Commissione 1 Assisi, 20 settembre 2004 Francesco Forti INFN-Pisa

3 20 settembre 2004F.Forti - BABAR: prospettive future2 Beauty of beauty factories Impressive physics program achieved at B-Factories –B mesons are a powerful laboratory Sizable mixing and CP violation HQET works and has predictive power Many transitions probe different quantities –e + e - machines are fantastic probes Very clean environment: ½-track trigger Coherent initial state allows true interference measurements and high tagging efficiency with low dilution –Luminosity counts Large samples allow precision measurements Rare and very rare decays are becoming more and more crucial.

4 20 settembre 2004F.Forti - BABAR: prospettive future3 Ieri hep-ph

5 20 settembre 2004F.Forti - BABAR: prospettive future4 Oggi 244 M 284 M CDF Detector

6 20 settembre 2004F.Forti - BABAR: prospettive future5 Domani: ancora fisica del B ? What: –PEP-II/Babar & KEK-B/Belle currently at peak luminosity  cm -2 s -1 –Integrated sample of > 1ab -1 for each machine by 2009 –Upgrade ideas/proposals to increase luminosity by a factor 10 to 100, for a sample size of 5-50 ab -1. Why: –High precision Standard Model Unitarity Triangle (UT) measurements –New Physics (NP) contributions to rare decays B.R. & Asymm. –Distinctive patterns may discriminate between models How: –Different upgrade scenarios are being considered: from 1.5 x to –Detector and machine complexity/cost undergo a phase transition around a few x cm -2 s -1 mainly because of backgrounds When: –in the era of LHCb, BTeV and LHC experiments. –Competitiveness and complementarity with hadron machines is a real issue.

7 20 settembre 2004F.Forti - BABAR: prospettive future6 Certamente ancora fisica del B ! LHCb, BTeV, Atlas, CMS will hopefully happen. –Will make existing B-Factories obsolete Pros: –Hadronic-B-Factories open up new realms of SM and NP measurements using B s and B c. Extensive physics program –High B production cross section allows searching for rare and very rare channels NP discovery potential is there Cons –Hadronic environment makes inclusive final states and final states with too many neutrals off-limits But exclusive charged states are great. –Trigger is crucial (and critical) Detached vertex is the core Need to be selective on physics process at trigger level –Initial state is incoherent Interference measurements difficult or impossible Tagging is a really tough job: CDF has εD 2 =2.6% now for the B s. BABAR/BELLE 1 nb 4 nb

8 20 settembre 2004F.Forti - BABAR: prospettive future7 Domani LHCb Super B ATLAS CMS BTeV

9 20 settembre 2004F.Forti - BABAR: prospettive future8 Nel frattempo… PEP-II/Babar luminosity projection (conservative) 0.5 ab ab

10 20 settembre 2004F.Forti - BABAR: prospettive future9 La prima decade del nuovo secolo Il programma di Babar (e Belle) fino al 2009 è ben definito –Con interventi ragionevoli il rivelatore funziona bene fino alla fine della decade –Integrare >1ab -1 per misurare al meglio il triangolo di unitarietà –Con un po’ di fortuna, dare degli hint di effetti di nuova fisica (vedi asimmetria nei pinguini b  sss(bar)) –Sfruttare la pulizia degli eventi e+e- per studiare stati, asimmetrie, polarizzazioni, fattori di forma, spettri, etc. ad ampio raggio In seguito ai recenti risultati Babar sta considerando se spostare di qualche mese il previsto shutdown del 2005 –Raddoppio della statistica nel 2005 invece che nel –Mantenere la competitività con Belle –Non perdere la (possibile) occasione di scoperta –Discussione in corso, conclusioni non prima di qualche mese

11 20 settembre 2004F.Forti - BABAR: prospettive future10 Il menu della Fisica Unitarity Triangle sides measurements –From (semi)leptonic decays, inclusive or exclusive –|V ub |, |V cb |, |V td | UT angles precision measurements –b  s penguin transitions very sensitive to new physics –CPV Asymmetries in B   K s, K s  0 compared with sin2 . –  measurement with B   and  ; direct CPV –  measurement with B  DK or similar channels. Rare decays –Exclusive and inclusive b  s  BFs, direct asymmetries, photon helicities –Exclusive and inclusive b  sl + l - BFs, A FB, CP asymmetries –B decays to states with large missing energy, such as B (d,s)  +  -, B  K (*) , b  s , B  D (*)  , B  X C  

12 20 settembre 2004F.Forti - BABAR: prospettive future11 New Physics in B physics In most cases the rates, particularly in hadronic decays, suffer from large theory uncertainties and not considered suitable for NP studies. The best NP observables in B physics seem to be: –Time-dependent CPV asymmetries in b  sss(bar), b  s dd(bar), and b  s  –Direct CP asymmetries in some cases (e.g. b  s/d  -maybe) –Ratio of rates (maybe) –b  sl+l-: CP asym., Forward-Backward asymmetry & its CP asym. –Rate of very rare decays B  l+l- –B  X  rate and polarization –Other near zeros: e.g. CPV in mixing

13 20 settembre 2004F.Forti - BABAR: prospettive future12 Neubert

14 20 settembre 2004F.Forti - BABAR: prospettive future13 Sources A lot of activity has been going on in the past couple of years –Study groups, Workshops, Theorists involvement –Many detailed, in-depth studies. Try to summarize numbers and conclusions from –Several Belle workshops belle.kek.jp/workshops –Babar workshops + Roadmap committee –Hawaii joint workshop In the following tables: –several empty spaces Different assumptions, missing studies, etc. –LHCb and BTeV numbers come from their presentations, such as from Beauty 2003: www-hep.phys.cmu.edu/beauty2003 –Updating…

15 20 settembre 2004F.Forti - BABAR: prospettive future14 Ingredients of the physics case Experimental sensitivities for B experiments (2 to 50 ab -1 ) –Statistical and systematical Theoretical uncertainties of the reference points based on SM. –Given these uncertainties, is there still any sensitivity to NP? Q NP – Q SM > 3  SM (Q) ? Comparison with sensitivities from the planned hadron collider experiments. –Can the super-B measurements compete and/or provide better information than Hadron experiments? –Note that super B Factories cannot do B s because of large X s

16 20 settembre 2004F.Forti - BABAR: prospettive future15 Standard Model Reference ObservableSM: reference pointSM: Expected range Time dependent CP Measurements b  sss(bar) & b  sdd(bar) & b  s  S(B   s )~Sin2  |sin2  S|<0.25 (0.05) S(B   ’Ks)~Sin2  |sin2  S|<0.3 (0.1) S(B   s   )~Sin2  |sin2  S|<0.2 (0.15) S(B  K* 0  (with K*   s   )~2(m s/ m b ) Sin2  |S|<0.1 (?) b  s/d  b  s/d  l +  l - ): Rates and A cp(dir) Acp(b  s  Acp(b  d  0.6% [-16%] (?)  (B  K*+  (B  K*0  sum) ~0 (isospin breaking)5 to 10% (?)  (b  d  (b  s  |Vtd/Vts| (from mixing)  cp (B  s l +  l - )  cp (B  d l +  l - ) <0.5% (0.05% for K* l +  l - ) ~(4.4+/-4 )% B(B  K      B(B  Ke + e - ) 11.0+/ A FB (K*l +  l - ):s 0 (zero crossing) / (5%) A FB (K*l +  l - ):CP asymmetry ~0 CPV in mixing: (|q/p|)~1 Very rare decays: B      B         X    Rate and   polarization ~2% Strict Limit Educated guess

17 20 settembre 2004F.Forti - BABAR: prospettive future16 Theoretical uncertainties Ligeti, ICHEP 2004

18 20 settembre 2004F.Forti - BABAR: prospettive future17 NP SUSY Effects

19 20 settembre 2004F.Forti - BABAR: prospettive future18 Other NP Effects

20 20 settembre 2004F.Forti - BABAR: prospettive future19 Unitarity Triangle - Sides e + e - Precision1 Year Precision MeasurementGoal3/ab10/ab50/abLHCbBTeV V ub (inclusive) syst =5-6%2%1.3% V ub (exclusive) ( p,r )exclusive syst=3%5.5%3.2% V cb (inclusive) V cb (exclusive) f b B (B  mn ) SM: B ~5x10 -7 f b B (B  tn ) B (B  tn ) SM: B ~5x s 6 s 13 s f b to ~ 10% V td /V ts ( rg/K*g) Theory 12%~3%~1%

21 20 settembre 2004F.Forti - BABAR: prospettive future20 Unitarity Triangle - Angles e + e - Precision1 Year Precision Measurement3/ab10/ab50/abLHCbBTeV a (pp) a (pp) ( S pp, B  pp BR’s + isospin) 6.7  3.9  2.1  -- a ( rp ) (Isospin, Dalitz) (syst  3  ) 3, 2.3  1.6, 1.3  1, 0.6  2.5  -5  44 a ( rr ) (penguin, isospin, stat+syst) 2.9  1.5  0.72  b (J/  K S ) (all modes) 0.3  0.17  0.09  0.57  0.49  g (B  D (*) K) (ADS) 2-3  ~10  <13  g (all methods)  77 88 Theory: a ~1° b ~ 0.2° g <<1°

22 20 settembre 2004F.Forti - BABAR: prospettive future21 Error on angles 0.5 ab -1 5 ab ab -1

23 20 settembre 2004F.Forti - BABAR: prospettive future22 CP Violation in b  s penguins Rare Decays – New Physics – CPV (?) e + e - Precision1 Year Precision MeasurementGoal3/ab10/ab50/abLHCbBTeV S(B0fKS)S(B0fKS) SM: <0.25 (0.05) (?)0.08?0.04? S(B0fKS+fKL)S(B0fKS+fKL) SM:<0.25 (0.05) S(Bh'Ks )S(Bh'Ks ) SM:<0.3 (0.1) S(BKsp0)S(BKsp0) SM:<0.2 (0.15) (?) S(BKsp0g)S(BKsp0g) SM:< (?) A CP (b  s g) SM: <0.6%2.4%1%0.5% (?) A CP (B  K* g ) SM: <0.5%0.59%0.32%0.14%-- CPV in mixing (|q/p|)<0.6% XX

24 20 settembre 2004F.Forti - BABAR: prospettive future23 b  s penguin SUSY contribution with new phases SM predicts for b  sss (almost) the same phase e -2iβ as in tree process b  ccs. However loops can also be sensitive to New Physics!,,uct “Tree-level b  u” u-tree CKM suppressed T/P < 0.1

25 20 settembre 2004F.Forti - BABAR: prospettive future24 Sensibilità alla nuova fisica  K S now Ciuchini, Franco, Martinelli, Masiero, & Silvestrini

26 20 settembre 2004F.Forti - BABAR: prospettive future25 Intriguing hints from penguins 2.7  from s-penguin to sin2  (cc) 2.4  from s-penguin to sin2  (cc)

27 20 settembre 2004F.Forti - BABAR: prospettive future26 Projections for Penguin Modes K*K* 5  discovery region if non-SM physics is 30% effect 2004=240 fb =1.5 ab -1 Similar projections for Belle as well Projections are statistical errors only; but systematic errors at few percent level Luminosity expectations : f 0 K S K S  0  K S  ’K S KKK S

28 20 settembre 2004F.Forti - BABAR: prospettive future27 Projections for Super B Factory f 0 K S K S  0  K S  ’K S KKK S K*K* 5  discovery region if non-SM physics is 15% effect Super B Factory 5-7x10 35 cm -2 s -1 Projections are statistical errors only; but systematic errors at few percent level Luminosity expectations : Scale change!

29 20 settembre 2004F.Forti - BABAR: prospettive future28 Use TDCP to probe the helicity structure: ( but limited to K *0  K s    ~  David Atwood, Michael Gronau, Amarjit Soni (1997) PRL 79,185(1997)  mixing Helicity Flip Suppressed by m s /m b  Expect: 0.1 ab -1 2 ab -1 5 ab ab ab -1 LHCBBTEV S(K s      (0.12) (?)XX Soni: m s is the “current” mass:  m s ~150 +/- 50 MeV), m b ~5 GeV  Theory error ~0.01 to 0.02 (??) (~30% of SM value of S) ~0.042 B 0 (bar) B0B0 The dominant SM amplitude gives: b  s  L, b(bar)  s  R NP can modify helicity structure: e.g. LR symmetry, higgs in loops BKsBKs

30 20 settembre 2004F.Forti - BABAR: prospettive future29 Radiative Penguins Very actively pursued Need improved theoretical predictions to match experimental precision

31 20 settembre 2004F.Forti - BABAR: prospettive future30 More Rare decays precision Rare Decays – New Physics e + e - Precision1 Year Precision MeasurementGoal3/ab10/ab50/abLHCbBTeV G( b  d  / G (b  s  -- B( B  D ( * ) tn )SM: B : 8x %5.6%2.5%-- B( B  s nn ) (K -,0, K* -,0 ) SM:Theory ~5% 1 excl: 4x10 -6 ~3 s -- B( B  invisible) <2x10 -6 <1x10 -6 <4x B( B d  mm ) --1/2 B( B d  tt ) ---- B(t  mg ) <

32 20 settembre 2004F.Forti - BABAR: prospettive future31 Recoil Physics The final efficiency is ~0.4% (per bb bar pair)  ~4000 B/fb -1 (at 30% purity)  1500 B 0 /fb -1  2500 B + /fb -1 > 10 7 recoil Bs in 10ab -1 Recoil cinematics well known Recoil flavor and charge is determined Event closure needed with neutrinos

33 20 settembre 2004F.Forti - BABAR: prospettive future32 b  sl + l - precision New Physics – K l + l -, s l + l - e + e - Precision1 Year Precision MeasurementGoal3/ab10/ab50/abLHCbBTeV B (B  K      / B (B  Ke + e - ) SM: 1~8%~4%~2%XX A CP (B  K* l + l - ) (all) (high mass) SM: < 0.05% ~6% ~12% ~3% ~6% ~1.5% ~3% ~1.5% ~3% (?) ~2% ~4% (?) A FB (B  K*l + l - ) : s 0 A FB (B  K*l + l - ) : A CP SM: ±5%~20%~9%9%~12% A FB (B  sl + l - ) : ŝ 0 27%15%6.7% A FB (B  sl + l - ) : C 9, C %20-30%9-13%

34 20 settembre 2004F.Forti - BABAR: prospettive future33 SM: S 0 NNLO error = 5% S 0 = / ~ C7/C9 In SM: A CP FB ~ 0 Determination of sign of AFB very important.  cp (B  s l +  l - ) SM: <0.5% (0.05% for K* l +  l)  cp (B  d l +  l - ) SM: - ~(4.4+/-4 )% B(B  s      B(B  se + e - ) SM: ~1 A FB (K*l +  l - ):s 0 (zero crossing) SM predicts with ~5% accuracy A FB (K*l +  l - ):CP asymmetry Very small in SM NP observables in s/d l+l- decay In dilepton rest frame N F = when l + along b dir N B = when l + opposite b dir

35 20 settembre 2004F.Forti - BABAR: prospettive future34 Super B-Factory Campioni di B > 10ab -1 /anno offrono la possibilità di investigare la NP, se la scala di massa ~ TeV. Campioni di 1ab -1 /anno offrono poco di più rispetto al programma attuale, a causa dei limiti degli errori teorici. Una macchina da 5-10 x cm -2 s -1 richiede upgrades molto significativi degli acceleratori e rivelatori esistenti. Possibili parametri di Super PEP

36 20 settembre 2004F.Forti - BABAR: prospettive future35 Super Babar High luminosity inevitably carries along high backgrounds Babar as-is is not suitable to work at high luminosity Upgrade complexity undergoes a “phase transition” around 3-5x10 35 cm -1 s -1 High luminosity options offer several technological challanges that require significant R&D For a detector that works up to L=1x10 36 cm -1 s -1 –Replace inner layers of SVT with thin pixels (outer layers with Silicon striplets?) and change to radiation hard readout electronics –Replace DCH with Silicon tracking system (some loss of momentum resolution) –Replace DIRC bars at smaller radius, and use readout system operating inside magnetic field –Replace CsI(Tl) crystals with radiation hard crystals (LSO, LYSO), or with Liquid Xe calorimeter –Replace IFR forward endcap with avalanche LSTs or Scintillating Fibers

37 20 settembre 2004F.Forti - BABAR: prospettive future36 The international scene KEK-B/Belle: A letter of intent has been put forward in February 2004 for a Super KEK-B machine and a Super Belle detector. –Luminosity ranges from 1x10 35 to 5x10 35 –Detector upgrades include: PEP-II/Babar: A “Roadmap committee” has prepared a report summarizing discussions and studies done over the past couple of years. –Current direction is to propose a “upgradable platform”: Start with 2x10 35 machine and detector, but already include an upgrade path to 7-8x10 35 for the 10ab -1 /year goal. –Detector upgrades include –Base detector possible with current technology, while full upgrade will require significant R&D Silicon striplets Small cell drift chamber Pure CsI calorimeter endcap Silicon striplets  thin pixels Small cell drift chamber  all silicon tracker Pure CsI calorimeter endcap  Liquid Xenon or LSO xtals

38 20 settembre 2004F.Forti - BABAR: prospettive future37 The OSBF Principle a.k.a. “One Super B Factory” It is unlikely that the HEP community has enough resources to build more than one Super B Factory –Encourage collaboration between Babar and Belle communities (and others) to join efforts –Joint workshop in January 2004 (Hawaii), second of a series, more to come Approval process lengthy –Connected to global funding political decisions: ITER, ILC –Unlikely to have serious funds before 2008 –Only if there is overall community agreement and support

39 20 settembre 2004F.Forti - BABAR: prospettive future38 Conclusioni Babar ha un brillante futuro per i prossimi 5 anni –Impressionanti le capacità di “inventare” nuove analisi Una Super B-Factory da 10ab -1 /year ha un potenziale di scoperta: –Gli effetti di NP nei loop sono significativi e accessibili –Nell’era di LHC Gli esperimenti LHC misureranno le masse della NP. Gli esperimenti di flavour misureranno gli accoppiamenti e le fasi. –Le misure di precisione sull’UT daranno ulteriori elementi Complementare e competitiva con LHCB/BTeV –No B s, ma su tutto il resto ottiene la stessa precisione o migliore –Sample pulitissimo (ad es. con la tecnica del recoil) –Stato iniziale coerente: permette studi interferometrici –Accesso ai canali con neutri o neutrini:  0 –Accesso a stati inclusivi e parzialmente ricostruiti Ci sono abbastanza risorse ? –E’ necessario definire una struttura di collaborazione tra Belle e Babar –Non necessariamente deve essere localizzata a SLAC o KEK: possono essere proposti altri siti ?

40 20 settembre 2004F.Forti - BABAR: prospettive future39 BACKUP

41 20 settembre 2004F.Forti - BABAR: prospettive future40 B d - unitarity    m(Bs)B->  KsB->Ms  indirect CP b->s  direct CP mSUGRA closedsmall SU(5) SUSY, GUT + R (degenerate) closedlargesmall SU(5) SUSY,  GUT + R (nondegenerate) closedsmalllarge small U(2) Flavor symmetry large sizable Unitarity triangleRare decay Pattern of Deviation from SM Predictions In most cases SM predictions are sufficiently under control as to motivate these highly sensitive measurements NP effects on B and t physics are model-dependent –In this context, model-dependent is not a dirty word –In fact, the pattern of New Physics effects in the flavor sector is diagnostic of the type of SUSY-breaking Y.Okada

42 20 settembre 2004F.Forti - BABAR: prospettive future41 Universal extra dimension effects


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