CP Violation at LHCb

Transcription

1 Kruger 212 Workhop on Dicovery Phyic at the LHC Kruger National Park, Dec 3-7, 212 CP Violation at LHCb Olaf Steinkamp on behalf of the LHCb collaboration Phyik-Intitut der Univerität Zürich Winterthurertrae 19 CH-857 Zürich

2 Source of CP violation (I) CP violation in mixing ( indirect CP violation) neutral meon ytem (KK, DD, BB, BB): particle-antiparticle mixing due to box diagram time evolution decribed by Schroedinger equation: i () d B dt B = ( 11 M i 12 M i Γ 11 2 Γ 2 22 M i 2 Γ 22 2 ) () B NP? B olution yield ma eigentate (= particle that propagate in vacuum): B,L = p B q B 12 M 12 i Γ 12 B,H = p B q B CP violation due to interference of 12 and M12 if φ M = arg M 12 /Γ 12 ( reult in q/p 1 : ma eigentate are not CP eigentate different tranition rate for B B and B B ) New Phyic can enter through heavy new particle in box and affect φ M Kruger212 LHCb (2/5)

3 Source of CP violation (II) CP violation in decay ( direct CP violation) K u due to interference of decay diagram with different weak and trong phae b B caue different decay amplitude for a u K- proce and it CP conjugate: Af /Af 1 meaure time-integrated decay rate aymmetry A± = Γ (B f) Γ (B f) Γ (B f) Γ (B f) B heavy particle in Penguin loop challenge: dientangle weak phae from trong phae u u New Phyic can then enter through new Kruger212 LHCb (3/5) K b interfering amplitude uually involve Penguin diagram b B K- NP? K u u K-

4 Source of CP violation (III) CP violation due to the interferenc of mixing and decay if final tate f acceible to both B and B: φ D CP violated due to interference between B direct decay and decay after mixing if Im q ( ) Af p φm B φd meaure time-dependent decay rate aymmetry: A CP (t) = Af J/ψ φ Γ (B (t= ) f (t)) Γ (B (t=) f(t)) Γ (B (t=) f(t )) Γ (B (t=) f(t)) = S in (Δ m t) C co(δ m t) Δ m = m(b, H ) m(b, L ) mot prominent example pre-lhcb: meaurement of CKM angle 2 in B J/ K by Babar and Belle NP can change phae of mixing (box diagram) and decay (if penguin) n.b. CP can be violated in thi cae even if q/p = 1 and Af/Af = 1 Kruger212 LHCb (4/5)

5 CP Why?olation New Phyic model uually predict new heavy particle! thee can enter in internal loop (Box diagram and Penguin), lead to izeable modification of CP phae the comparion of precie meaurement of CP phae with precie prediction from Standard Model can therefore reveal the preence of New Phyic thee indirect earche for New Phyic make ue of the appearance of virtual particle in loop diagram are therefore enitive to higher ma cale than direct earche for new particle claic example: CP violation in KK (1964) prediction of 3rd quark family (top direct dicovery 1995) moreover, the pattern of oberved deviation can hint at the tructure of the New Phyic at work Kruger212 LHCb (5/5)

6 LHCb Apparatu VErtex muon ytem RICH detector LOcator p B B p interaction point Eugeni' talk on Tueday tracking ytem calorimeter [The LHCb Detector at the LHC, JINST 3 (28) S85] Kruger212 LHCb (6/5)

7 Key Feature ~ 7 mm 35 p B meon are the elephant of the particle zoo they are heavy and they live long. (T. Schietinger) impact parameter reolution reolve fat B-B ocillation momentum, invariant ma reolution identify econdary vertice proper time reolution K/ eparation againt peaking background flavour tagging elective and efficient trigger, alo for hadronic final tate againt combinatorial background magnetic field revered regularly to cancel detector aymmetrie Kruger212 LHCb (7/5)

8 Key Feature [LHCb-CONF-211-5] [LHCb-CONF-212-2] [JHEP 1 (212) 37] B J /ψ φ σ (m )= B 6. MeV/c 2 impact parameter reolution reolve fat B-B ocillation momentum, invariant ma reolution identify econdary vertice proper time reolution K/ eparation againt peaking background flavour tagging elective and efficient trigger, alo for hadronic final tate againt combinatorial background magnetic field revered regularly to cancel detector aymmetrie Kruger212 LHCb (8/5)

9 Overview Short introduction CP violation in BB mixing from emileptonic decay CP phae from B J/ and B J/ - CKM phae from B± DK± and B± D ± Tree decay CP violation in charmle B decay ( from loop ) Summary and outlook: LHCb upgrade Kruger212 LHCb (9/5)

10 CP violation in B -B mixing

11 Semileptonic Aymmetry remember, CP violated in B-B mixing if φ M = arg M 12 / Γ 12 ( ) can be meaured in emileptonic decay aymmetry a l = Γ (B D μ X) Γ (B D μ X) Γ (B D μ X)Γ (B D μ X) = Δ Γ Δ m NP? tan φ M (, m: lifetime and ma difference between the two ma eigentate) predicted to be very mall in Standard Model a l = (1.9 ±.3) 1 5 [A.Lenz, arxiv: ] very enitive to poible New Phyic contribution in box diagram LHCb analyi of 1. fb-1 193k ignal event very low background D D D D [LHCb-CONF ] Kruger212 LHCb (11/5)

12 Semileptonic Aymmetry LHC collide proton on proton B B o B meon are NOT like elephant they forget! production aymmetry, ap ~ 1 % but: ap teongly diluted by the very rapid B-B ocillation Araw = N (D μ ) N (D μ ) N (D μ )N(D μ ) = al 2 [ ap al 2 ] Γ t e co(δ m t) ε (t )dt Γ t e coh(δ Γ t /2) ε (t)dt =2 1 3 for LHCb acceptance ε(t) detection aymmetrie: meaured from data uing variou control channel alo: look at data eparately for the two magnet polaritie [LHCb-CONF ] magnet up magnet down Kruger212 LHCb (12/5) combined

13 Semileptonic Aymmetry LHCb reult a l = (.24 ±.54 (tat) ±.33 (yt) ) % mot precie meaurement to date conitent with Standard Model remember: D report 2.9 deviation [LHCb-CONF ] preliminary from Standard Model in meaurement of like-ign dimuon aymmetry Aμ μ = N (μ μ ) N (μ μ ) N(μ μ )N (μ μ ).6 a l.4 a dl for D [D collaboration, arxiv: ] LHCb and D reult compatible with each other at < 2 level Kruger212 LHCb (13/5)

14 from B J/ and B J/ -

15 CP violation in B J/ example for CP violation in interference between mixing and decay CP violating phae φ D B φ = φ M 2 φd φm J/ψ φ B φd predicted to be very mall in Standard Model B-B mixing phae M expected to be very mall decay dominated by Tree diagram with D ~, SM φ D = arg (V cb V c ) only mall contamination from Penguin φ =.36±.2 rad [Phy.Rev.D 84 (211) 335] highly enitive to New Phyic contribution in B -B mixing Kruger212 LHCb (15/5) NP?

16 CP violation in B J/ time-dependent CP aymmetry for CP eigentate f with eigenvalue f= ±1 ACP (t) = Γ (B (t=) f) Γ (B (t=) f) Γ (B (t=) f) Γ (B (t=) f) = η f in φ in(δ m t) need to determine flavour of B meon at t= mi-tag fraction tag need to reolve B-B ocillation finite proper time reolution t ACP (t) (1 2 ω tag ) e 12 Δ m 2 σ 2t η f in φ in(δ m t) final tate in B J/ i a mix of CP even and odd (LJ/ =,1,2) three polariation amplitude, plu contribution from S-wave K K- time-dependent angular analyi to dientangle thee and determine finite lifetime difference between CP eigentate in BB ytem not well meaured yet, need to be determined imultaneouly with Kruger212 LHCb (16/5)

17 CP violation in B J/ not yet ued in thi analyi oppoite-ide flavour tagging: imply B flavour at production from decay propertie of the aociated b hadron produced neural net algorithm uing charge of lepton, kaon, incluive vertex calibrated on flavour-pecific decay uch a B± J/ K± effective tagging power: ε tag (1 2 ω tag )2 = (2.35±.6(tat)) % [LHCb-CONF ] preliminary ame-ide tagging (charge of K± from hadroniation chain) not yet ued Kruger212 LHCb (17/5)

18 CP violation in B J/ time-dependent angular fit uing tranverity angle = ( =, =, = K) full fit function: phyic parameter: S in φ ; D co φ ; Δ m ; Δ Γ ; A ; A ; A ; δ ; δ ; δ two-fold ambiguity in olution: fit function invariant under tranformation ( φ, Δ Γ, δ, δ ) ( π φ, Δ Γ, 2 π δ, δ ) Kruger212 LHCb (18/5)

19 CP violation in B J/ LHCb analyi baed on 1. fb-1 21k ignal event [LHCb-CONF-212-2] world' larget ample only few % background angular fit cleanly eparate CP CP even/odd component CP- different lifetime clearly viible in fit projection CP CP CP CP- CP- CP- Kruger212 LHCb (19/5)

20 CP violation in B J/ reult conitent with Standard Model prediction φ =.1 ±.11(tat) ±.27 (yt) rad firt obervation (> 5 ignificance) of [LHCb-CONF-212-2] preliminary Δ Γ =.116 ±.18(tat) ±.6(yt) p 1 both reult dominated by tatitical uncertaintie Kruger212 LHCb (2/5)

21 Sign of reolve two-fold ambiguity [PRL 18 (212) 24181] (φ, Δ Γ, δ, δ ) (π φ, Δ Γ, 2 π δ, δ ) ( olution I ) ( olution II ) looking at trong phae difference = - between KK- P-wave and S-wave amplitude a a function of m(kk-) around the (12) P-wave: going through (12) reonance expect rapid poitive phae hift S-wave: non-reonant tail from f(98) expect no ignificant variation of phae LHCb analyi baed on.37 fb-1 determine in four KK- ma bin olution correponding to > elected with 4.7 ignificance Kruger212 LHCb (21/5)

22 from B J/ [arxiv ] dominated by f(98) - from modified Dalitz-plot analyi: > 99.7 % CP odd at 95 % C.L. in 775 < m( -) < 155 MeV/c² [arxiv ] meaurement in B J/ baed on ~74 candidate from 1. fb-1 lower BF than B J/ but no angular analyi required.4 φ = (tat) (yt) rad Kruger212 LHCb (22/5)

23 Combination and Comparion imultaneou fit of B J/ and B J/ φ =.2 ±.83(tat) ±.27 (yt) rad mot precie meaurement to date excellent agreement with [LHCb-CONF-212-2] preliminary Standard Model prediction but till pace for poible contribution from New Phyic preciion completely dominated by tatitical uncertainty expect ignificant improvement with more data Kruger212 LHCb (23/5)

24 Combination and Comparion ome tenion between meaurement and dimuon aymmetry from D Kruger212 LHCb (24/5)

25 CKM angle from Tree Decay

26 CKM angle from Tree Decay CKM fit o far a huge ucce tory for the Standard Model need more precie meaurement to tet for ubtle effect from New Phyic leat well contrained CKM parameter by direct meaurement: ( γ = arg V cd V cb ) γ = (66 ±12) o [CKMfitter] γ = (72 ±9) o [UTfit] Tree-level B decay: theoretically clean meaurement of V ud V ub no loop largely unaffected by poible effect from New Phyic but experimentally very challenging purely hadronic final tate ( trigger, K/ eparation) mall branching fraction ( need large number of B') Kruger212 LHCb (26/5)

27 CKM angle from Tree Decay u B b u Vub B u DK D f u b c V cb K u D f c i δd rd ~ 1 for GLW, ~.5 for ADS [f]dk- B rb e K u rd e - D K- i(δ B γ ) rb ~.1 time-integrated method: exploit interference of B± DK± [f]d K± and B± D K± [f]d K±, where final tate [f]d i acceible to D and D GLW: CP eigentate D KK-, D combined analyi [PLB 253 (1991) 483, PLB 265 (1991) 172] ADS: favoured D K / uppreed D K - - [PRL 78 (1997) 257, PRD 63 (21) 365] GGSZ: Dalitz-plot analyi of 3-body D K - of all mode to extract and hadronic parameter rb, B, rd, D [PRD 68 (23) 5418] [PRD 7 (24) 723] Kruger212 LHCb (27/5)

28 from Tree: GLW mode form ratio and aymmetrie of decay rate cancellation of ytematic R CP = ACP = Γ (B [h h ]D K ) Γ (B [h h ]D K ) [ 1 /2 Γ (B [K π ]D K ) Γ (B [K π ]D K ) Γ (B [h h ]D K ) Γ (B [h h ]D K ) Γ (B [h h ]D K ) Γ (B [h h ]D K ) = ] = 1 r2b 2 r B co δ B co γ 2 r B co δ B co γ R CP LHCb analyi of 1. fb-1 clear aymmetry in B± DK± and (a expected) no aymmetry in B± D ± ACP (KK) = ( 14.8 ± 3.7 ± 1.) % [PLB 713 (212) 351] ACP (π π ) = ( 13.5 ± 6.6 ± 1.) % Kruger212 LHCb (28/5)

29 from Tree: ADS mode ratio and aymmetrie of decay rate to flavour-pecific final tate R ADS = Γ (B [K π ]D K ) Γ (B [K π ]D K ) Γ (B [K π ]D K ) Γ (B [K π ]D K ) AADS = = r 2B r 2D 2 r B r D co(δ B δ D ) co γ Γ (B [K π ]D K ) Γ (B [K π ]D K ) Γ (B [K π ]D K ) Γ (B [K π ]D K ) = 2 rb rd in(δ B δ D ) in γ R ADS LHCb analyi of 1. fb-1 firt obervation of the rare ADS decay (1 ignificance) evidence for aymmetry in [arxiv ] B± DK± (4 ignificance) AADS (DK) = ( 52 ± 15 ± 2) % hint for aymmetry alo in B± D ± (2.4 ignificance) AADS (D π) = ( 14.3 ± 6.2 ± 1.1) % Kruger212 LHCb (29/5)

30 from Tree: D K imilar to 2-body ADS, but different value of rd and D add tatitic but alo new information [LHCb-CONF-212-3] preliminary LHCb analyi of 1. fb : firt obervation of rare ADS decay (1 in B± D ±, 5.1 in B± DK±) -1 RADS (DK) = (1.24 ±.27) % AADS (DK) = (4.2 ± 2.2) % RADS (D π ) = (.369 ±.36) % AADS (D π ) = (13 ± 1) % ytematic mall, dominated by particle identification (R) production, interaction, detection aymmetrie (A) Kruger212 LHCb (3/5) for all from Tree analye

31 from Tree: LHCb Impact Kruger212 LHCb (31/5)

32 from Tree: GGSZ exploit interference pattern in D Khh- Dalitz plot (h= K) powerful method, dominate preciion on from B factorie complication: trong phae difference D varie acro Dalitz plot rich reonance tructure, difficult to model correctly model-independent approach choen to minimize ytematic: divide Dalitz plot into region K - of ~ contant D uing input KKK- from CLEO meaurement [PRD82 (21) 1126] determine B and B- event yield in each region i: Ni (B± ) = K,i (x 2± y2±) K ±,i 2 K, i K, i { x ± <co δ D > i y ± <in δ D > i aymmetrie meaured in x ± = r B co( δ B ± γ ) flavour-pecific D decay y ± = r B in ( δ B ± γ ) Kruger212 LHCb (32/5) } trong phae meaured by CLEO meaured by CLEO

33 from Tree: GGSZ LHCb analyi of 1. fb-1 ~ 65 B± [K -]D K± candidate ~ 1 B± [KKK-]D K± candidate preciion on x±, y± imilar to B factorie ytematic uncertainty dominated by [PLB 718 (212) 43] aumption of no CPV in B D (ued to determine efficiencie) x = (. ± 4.3 ± 1.5 ±.6) % y = (2.7 ± 5.2 ±.8 ± 2.3) % x = ( 1.3 ± 4.4 ± 1.8 ± 1.4) % y = (.9 ± 3.7 ±.8 ± 3.) % tat yt CLEO input Kruger212 LHCb (33/5)

34 from Tree: LHCb Combination LHCb average from combination of B± DK± uing frequentit approach to combine the hown reult from GLW/ADS B± [hh-]d K± [PLB 713 (212) 351] ADS 4-body B± [ K ]D K± [LHCb-CONF-212-3] GGSZ B± [Khh-]D K± γ = [PLB 718 (212) 43] ( 71 ) [LHCb-CONF ] preliminary preciion already comparable with average from B factorie Babar: γ = ( 16 ) Belle: ( 14 ) γ = [43.9º - 95% C.L. Kruger212 LHCb (34/5)

35 Charmle B decay: toward from Loop

36 from Loop 2-body charmle B decay: from /d interference of b u Tree diagram u and b (d) Penguin diagram enitive to poible New Phyic b B d /d K/ b B u d K/ u u d d - - contribution in Penguin loop hadronic uncertaintie can be /d controlled uing U-Spin ymmetry between B and B decay [Fleicher, EPJC 52 (27) 267] u b B /d /K B u b K- /K u u K- two approache: time-dependent CP aymmetry in B - and B KK- time-integrated CP aymmetry in B K - and B K- alo: time-integrated CP aymmetry in 3-body charmle B ± decay Kruger212 LHCb (36/5)

37 Time-dependent CPV in B() hh meaure time-dependent aymmetry of decay rate ACP (t) = Γ (B() (t=) f) Γ (B() (t=) f) () () Γ (B (t=) f) Γ (B (t=) f) = mix Adir co(δ m t) A co(δ m() t) f () f coh ( Δ Γ ( ) 2 t) A ΔΓ f inh( Δ Γ ( ) 2 t) ue flavour tagging algorithm to determine flavour of B () at production LHCb analyi of.69 fb-1 fix value of md and m and ign of to previou LHCb meaurement ue B K to calibrate tagging and determine mi-tag probability firt B - aymmetry at a hadron collider [LHCb-CONF-212-7] firt B KK- aymmetry ever Kruger212 LHCb (37/5)

38 Time-dependent CPV in B() hh- B KK- B - Aπ π =.11 ±.21 ±.3 dir AKK =.2 ±.18 ±.4 Amix π π =.56 ±.17 ±.3 mix AKK =.17 ±.18 ±.5 dir [LHCb-CONF-212-7] preliminary dir Aπ π reult favour Babar [arxiv: ] over Belle [PRL 98 (27) 21181] Kruger212 LHCb (38/5)

39 Direct CP Violation in B() K time-integrated aymmetry of decay rate to flavour-pecific final tate ACP = LHCb analyi of.35 fb-1 B K / B K Γ (B() f) Γ (B() f) Γ (B() f) Γ (B() f) [PRL 18 (212) 2161] ACP = (.88 ±.11 ±.8) > 6 firt obervation of CP violation at a hadron collider B K / B K ACP = (.27 ±.8 ±.2) 3.2 firt evidence for CP violation in the B ytem production/detection aymmetrie mall, corrected uing control channel dominating ytematic: different K/K- interaction cro-ection Kruger212 LHCb (39/5)

40 CP Violation in 3-body B decay ± again, interference of b u Tree tranition and b (d) Penguin Γ (B f ) Γ (B f ) ACP = Γ (B f ) Γ (B f ) f = ± { K ± π π, K ± K K [LHCb-CONF ] π ± π π, K K π ± [LHCb-CONF ] preliminary LHCb analye uing 1. fb-1 meaure production and detection aymmetrie from B± J/ K± ACP (K π π ) =.34 ±.9 ±.4 ±.7 ACP (K K K ) =.46 ±.9 ±.5 ±.7 ACP (π π π ) =.12 ±.2 ±.19 ±.7 ACP (K K π ) =.153 ±.46 ±.19 ±.7 ± ± tat yt ± ± knowledge of CP aymmetry in B± J/ K± Kruger212 LHCb (4/5)

41 CP Violation in 3-body B decay ± analye alo performed a a function of phae pace [LHCb-CONF ] ubdivide Dalitz plot into bin of ~ equal population [LHCb-CONF ] determine aymmetry in each bin preliminary oberve large local aymmetrie in all four channel interpretation pending (not related to intermediate reonance) m2(k ±) B± KK- ± m2(kk-) B- B Kruger212 LHCb (41/5)

42 Concluion and Outlook

43 Concluion LHC and LHCb are a pectacular ucce o i the Standard Model up to now but current preciion of meaurement till leave lot of room for ub-dominant contribution from New Phyic Kruger212 LHCb (43/5)

44 Outlook: LHCb Upgrade LHC and LHCb are a pectacular ucce o i the Standard Model till current preciion of meaurement till leave lot of room for ub-dominant contribution from New Phyic almot all LHCb reult are completely dominated by tatitical uncertaintie leading ytematic uncertaintie will alo decreae with increaing tatitic NEED MORE STATISTICS THE LHCb UPGRADE! TeV TeV TeV LHC LS TeV LHC LS2, LHCb upgrade fb-1 per year 222 Kruger212 LHCb (44/5)

45 LHCb Upgrade goal: reach meaurement preciion that matche theory uncertaintie [CERN-LHCC-212-7] Kruger212 LHCb (45/5)

46 Upgrade two line of attack increae trigger efficiencie for hadronic final tate read out the full detector at the LHC bunch-croing frequency operate the detector at up to x 5 higher luminoity new main tracker to cope with increae in particle denitie expected increae in rate (compared to 211): x 1 for channel involving final-tate muon x 2 for channel to fully hadronic final tate detail are decribed in Letter of Intent [CERN-LHCC-211-1] Framework TDR [CERN-LHCC-212-7] endored by the LHCC Kruger212 LHCb (46/5)

47 Reminder: Current LHCb Trigger Hardware level (L): maximum output rate 1 MHz typical threhold 212: ET(e/γ) > 2.7 GeV ET(h) > 3.6 GeV pt(μ) > 1.4 GeV Software level (HLT): ~ 3 tak in parallel on ~ 15 node Combined efficiency (LHLT): ~ 9 % for di-muon channel ~ 3 % for multi-body hadronic final tate Offline proceing: ~ 11 event, 7 TB recorded per year Kruger212 LHCb (47/5)

48 Upgrade 212/213: R&D, technology choice, preparation of ub-ytem TDR 214: : contruction and intallation funding, procurement Kruger212 LHCb (48/5)

49 819 member 6 Intitute 16 countrie (October 1t, 212) The engine i running, the afari ha only jut begun fetch your binocular and join the party?

50 Not Mentioned B K K effective lifetime B J/ f effective lifetime [ PRL 19 (212) 1522] both enitive to new phyic in B-B mixing BF (B J/ ') [PLB 716 (212) 393] [arxiv: ] another channel to meaure BF (B J/ K*) [ PRD 86 (212) 7112] to etimate penguin contamination in J/pi phi GLW-type analyi of B D K* [LHCb-CONF ] Time-dependent CP violation in B D K± [LHCb-CONF ] other channel to meaure gamma from Tree BF (B D()D()) CP violation in B K* - CP violation in B K* ACP (CP violation in D hh-) [ LHCb-CONF-212-9] Eugeni' talk on Tueday [arxiv: ] [ Nucl Phy B 867 (213) 1] Kruger212 LHCb (5/5) [PRL 18 (212) 11162]