Физика каонов в экспериментах с участием ОИЯИ

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Presentation transcript:

Физика каонов в экспериментах с участием ОИЯИ Юбилейный семинар И.А.Савина Физика каонов в экспериментах с участием ОИЯИ В.Кекелидзе Дубна, 7 декабря 2010 7 декабря 2010 1 /53

Формфакторы в полулептонных распадах KL Содержание БИС: Регенерация KL → KS Формфакторы в полулептонных распадах KL EXCHARM : Эффект выстроенности спинов K*(890) NA48: Обнаружение прямого CP-нарушения NA48/1: Редкие распады KS (поиск «новой физики») NA48/2: Поиск зарядовой асимметрии (СР-нарушения) в распадах K Загадка матрицы унитарности (угол Кабиббо) Вклад в развитие ChPT – КХД низких энергий (“cusp” эффект; распад Ке4; редкие распады K) NA62: Сверхредкие СР нарушающие распады K (поиск «новой физики») Заключение 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 2 /53

БИС one of the first electronic experiment at Serpukhov accelerator U-70 (1970-1976) Study of neutral kaons 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 3 /53

KL – KS regeneration has been studied for the first time On Hydrogen, Deuterium & Carbon at Serpukhov energies (U-70) Clear picture was obtained of amplitude degeneration with the energy rise, indicating on the Pomerantchuk Theorem K.F. Albrecht et.al., NP B93(1975)237. V.K. Birulev et.al.,NP B115(1976)249. K.-F. Albrecht et.al.,NP B158(1979)29. 4 /53

Vector & axial FF were measured in Ke3 & Km3 decays Ke3: l+ = (3.06 ± 0.34) x 10-2 ~ 74k events V.K.Birulev et al., NP B182(1981)1. БИС EXCHARM I.Savin 5 /53

EXCHARM magnetic spectrometer in the neutral beam extracted from U-70 study of polarized phenomena Search for multi-quark 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 6 /53

For the fist time: Spin alignment of K For the fist time: Spin alignment of K*(892) ± mesons produced in neutron-carbon interactions The values of ρ00 obtained in the transversity frame are: 0.424±0.011(stat)±0.018(sys) for K∗(892)+ 0.393±0.025(stat)±0.018(sys) for K∗(892)− r00 Significant Pt dependence of ρ00 has been observed in K∗(892)+ production K*(892)+ K*(892)- Pt, GeV/c 7 /53

NA48 (the first run at CERN SPS in 1997) observation of direct CP-violation 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 8 /53

СР-нарушение в системе нейтральных каонов СР-нарушение (1964) «непрямое» - за счет смешивания состояний (сохранение К1)   K0 K0 KL=K2+ P K0 KS=K1+2 out in  in out не могло бы повлиять на бариогенезис СР-нарушение в распадах К2 – «прямое» 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 9 /53

Measurement of direct CP-violation in neutral kaon decays  =A(KL  +) / A(KS  +) = ||  exp(i) 00 = A(KL  00) / A(KS  00) = |00|  exp(i00 )  = (43.4  0.7)º 00-  = (0.2  0.4)º (CPT)  =  + ` 00 =   2 ` The measured value: Re(`/ ) = (1  R) / 6 R =  00 /  2 (KL  00) / (KS  00) double Ratio: R  ————————————— (KL  +) / (KS  +) 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 10 /53

simultaneous KS & KL beams 4 decay channels are detected simultaneously in common decay volume ~ collinear KS и KL beams 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 11 /53

2-3M K/spill (/K~10),  decay products stay in pipe; The NA48 detector Main detector components: Magnetic spectrometer (4 DCHs): 4 views/DCH: Δp/p = 1.0%+0.044%*p [GeV/c]. Hodoscope fast trigger (150ps). Liquid Krypton EM calorimeter (LKr)‏ Hadron calorimeter Muon veto counters Photon vetoes Beam pipe 2-3M K/spill (/K~10),  decay products stay in pipe; flux ratio: K+/K–  1.8 K± beams 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 12 /53

Liquid Krypton EM calorimeter (LKr)‏ The first ISTC project at CERN (1995) liquid krypton (~10m3 at 120 K) 13212 cells, granularity 2x2 cm2 E/E = 3.2%/E1/2+0.9%/E + 0.42% [GeV] x=y=0.42/E1/2 + 0.6mm (1.5 mm @ 10 GeV) 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 13 /53

Systematic corrections and uncertainties (’98-’99 data) 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 14/53

Stability checks of R 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 15 /53

Results of Re(’/) Re(’/) = (14.7  2.2) x 10-4 5.33 x 106 PL B465,335(1999); EPJ C22(2001)231 PL B544(2002)97 Re(’/) = (14.7  2.2) x 10-4 NA48 results 5.33 x 106 KL00 decays 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 16 /53

PDG 2006 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 17/53

NA48/1 (run at CERN SPS in 2002) Search for new physics 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 18 /53

Consequence of measurements Br (KS  0 l + l ) (t=Vts*Vtd) sensitivity to Im lt Br(KL 0 е+е)CPV10-12  15.3 as2  6.8as Im(t)104 +2.8 [Im(t)104 ]2 (KTEV: Br < 5.110 10 ) constructive interference Br(KS 0  + )= (2.8 + 1.5./-1.2  0.2sys)10-9 (6 events) J.R.Batley et al.,PL B576(2004)197 NA48/1 first observation: (7 events): Br = (3.0 + 1.5./-1.2  0.2sys)10-9 J.R.Batlay et al.,PL B599(2003)43 Br(KS 0 e +e ) = 5.2 109 as2 19 /53

Br(at z > 0.2) = (4.9 1.6stat 0.9sys)10-8 2000 data First observations KS   0  PL B578(2004)276. Br(at z > 0.2) = (4.9 1.6stat 0.9sys)10-8 prediction of PT: Br (Ks  0) < 3.8  10-8 (z=m2/m2K> 0.2) KS   + e +e  Eur.Phys.J.C(2003)33 Br = (4.68  0.23stat  0.21syst)10-5 A() = (1.0  4.0stat  1.5syst)% to estimate a boundary on the indirect CPV term in KL  + e + e  20 /53

NA48/2 (approved by SPSC CERN in 2002) 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 21 /53

The Goals of NA48/2 Direct CP violation in K±  ± +  , K±  ± 0 0 (Ag ) < 210 – 4 (limited by statistics) g + - g - Ag = ———— g+ + g - Rare decays: to test PT & search for ACP Ke4 - scat. length ( ) < 1102 ( > 106 events) K   , K  0 DE K  e+ e, K  + , Ke2, K l  l+l, K  0 , K  0 l+l, … etc. Semileptonic decay Br’s: Ke3, K3 to improve precision of |Vus| & check CKM unitarity search for fT, fS (less systematics) 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 22/53

Search for charged asymmetry in K decays (CP-violation) 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 23 /53

Main goal – search for CP asymmetry in decays Experiment NA48/2 Main goal – search for CP asymmetry in decays K(3) 2003 run: ~ 50 days 2004 run: ~ 60 days Total statistics in 2 years: K  +: ~4·109 K  00: ~1·108 Rare K± decays: BR’s down to 10–9 were measured > 200 TB of data recorded 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 24 /53

Charged asymmetry in decay K(3) Experimental precisions before NA48/2: E. Gámiz et al., JHEP 10 (2003) 42 [Ag~10-3, dominated by systematics] SM estimate (NLO ChPT): Agc = (–1.41.2)10–5; Agn = (1.10.7)10–5. Smith et al. (1975) “neutral” 10-2 Ford et al. (1970) |Ag| HyperCP prelim. (2000) TNF (2005) “neutral” 10-3 NA48/2 proposal G. D’Ambrosio et al., PLB480 (2000) 164 Models beyond the SM predict substantial enhancement partially within the reach of NA48/2. “neutral” 10-4 “charged” SUSY & 10-5 SM New physics Asymmetry of integrated decay widths is strongly suppressed. 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 25 /53

NA48/2 simultaneous K+ & K- beam line PK spectra, 603 GeV/c NA48/2 simultaneous K+ & K- beam line 2-3M K/spill (/K~10),  decay products stay in pipe. Flux ratio: K+/K–  1.8 Simultaneous K+ and K beams: high charge symmetry of experimental conditions 54 60 66 magnet K+ K+ BM beam pipe Be target z focusing beams K ~71011 ppp, 400 GeV K Second achromat Cleaning Beam spectrometer (resolution 0.7%)‏ Front-end achromat Quadrupole quadruplet Beams coincide within ~1mm all along 114m decay volume Momentum selection Focusing  sweeping vacuum tank 10 cm He tank + spectrometer 1cm not to scale 50 100 200 250 m

Формализм распада K±  (3) ± Матричный элемент: |M(u,v)|2 ~ 1 + gu + hu2 + kv2 Далиц плот зарегистрированных распадов Система покоя К: u = 2mK∙(mK/3Eodd)/m2 v = 2mK∙(E1E2)/m2. прямое CP-нарушение: асимметрия параметров Ag = (g+g)/(g++g)  0 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 27 /53

Obtained asymmetry in decays of К K± ±00 K± ±+– [1] [2] [3] [4] [1] [2] [3] [4] [1] Ford et al. at BNL (1970) [2] HyperCP at FNAL, prelim. (2000) [3] NA48/2 2003 final [4] NA48/2 2003+2004 prelim. [1] Smith et al. at CERN-PS (1975) [2] TNF at IHEP Protvino (2005) [4] NA48/2 2003+2004 Ag x 104 g = (0.6 ± 0.7stat ± 0.4trig ± 0.5syst)10-4 g = (0.6 ± 0.9)  10-4 Agc = (1.5 ± 1.5stat ± 0.9trig ± 1.3syst)10-4 Agc = (1.5 ± 2.2)  10-4 Ag0 = (1.8 ± 1.7stat 0.6syst)10-4 = (1.8 ±1 .8)10-4 EPJ, C52: 875(2007) 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 28 /53

Unitarity Matrix Puzzle 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 29 /53

PDG contradicted with CKM Unitarity test of CKM Unitarity 10-5  = |Vus| contributes ~50% to the total uncertainty Br, K, f+(0)  (Ke3)  Vud .V*ud  Vus.V*us  Vub.V*ub  1 K+  0e + : PDG: Br = (4.86 ± 0.06)% Recent BNL data (E-865): Br = (5.17 ± 0.02 ± 0.09 ± 0.04)% based on ~ 70k events PDG BNL, E-865 KTEV |Vus| unitarity Hep-ex/0406001 NEW 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 29 /53

NA48/2 Results J.R.Batley et al.,EPJ C50(2007)329. Contributed to solve this puzzle G(K+ 0 e+ n) / G(K+ + 0) = 0.2470 ± 0.0009 ± 0.0004syst based on ~ 87k events G(K+ 0 m+ n) / G(K+ + 0) = 0.1637 ± 0.0006 ± 0.0003syst based on ~ 77k events G(K+ 0 e+ n) / G(K+0 m+ n) = 0.663 ± 0.003 ± 0.001syst based on ~ 77k events 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 30 /53

pi-pi scattering length the ChPT basic parameters Measurement of pi-pi scattering length the ChPT basic parameters 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 31 /53

 -  scattering lengths S-wave scattering lengths a0, a2 (for I=0, 2) - basic parameters of ChPT (Chiral Perturbation Theory or low energy QCD) Theory predictions (inits of 1/m): “Universal Band” (from Roy equations) PLB36 (1971) 353 S.Weinberg, PRL17(1966) 616. a2 ChPT prediction: G.Colangelo, J.Gasser, H.Leutwyller PRL86 (2001) 5008. a0 ChPT constraint 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 32 /53

Measurement of (a0, a2) in experiments: Traditional methods: K → p+ p- e n (Ke4 – decay) life time of mesoatoms for the first time done in NA48/2 experiment: K → p p0 p0 (K3pi – decay) “cusp effect” NA48/2 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 33 /53

K → p+ p- e n 1.13 M decays The measurements of: Form-Factors pion-pion scattering lengths: a0 and a2 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 34 /53

Ke4 selection & background Signal (p+ p- e n) topology: 3 charged tracks, good vertex 2 opposite sign pions 1 electron (ELKr /P ~ 1) Main background sources: a) K+  [p-  e-n]p+p+ b) K+  [p0  e+e- (g)] (p0) p+ Background seen in «wrong sign» (WS) component (same sign pions) a) 1(WS) / 2(RS) b) 1(WS) / 1(RS) Total background is at the level of 2 x 0.3 % (estimated from WS events & checked by MC) 1.13 M of fully reconstructed Ke4 (2003+2004 data) 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 35 /53

K → p+ p- e n (Ke4) formalism a rare decay [ B.R. = (4.09 ± 0.09) x 105 ] described by 5 variables K  p*(e) e e direction of the total e+e momentum in the K+ R.F. the total P( in the K+ R.F. p*()   5 Cabibbo–Maksymowicz variables: For K  K    e  e  s ≡ M2 , se ≡ Me2 e ,,  In the partial wave expansion (only S, P) the amplitude can be written using 4 form factors & 1 phase shift: F=Fseis+Fpeipcos G=Gpeip H=Hpeip  = s - p 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 36/53

Ke4 phase shift measurement isospin correction (10-15 mrad) to all published points — downward shift errors — combined stat. and syst.; fit to NA48/2 data alone Systematic errors: bin to bin correlated: background level; isospin corrections - bin to bin uncorrelated: fitting procedure; trigger efficiency; acceptance control; background shape; electron identification; radiative correction 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 37/53

Ke4 phase shift measurement isospin correction (10-15 mrad) to all published points — downward shift errors — combined stat. and syst.; fit to NA48/2 data alone errata published in PRL105(2010)019901 PRD81(2010)119903 Systematic errors: bin to bin correlated: background level; isospin corrections - bin to bin uncorrelated: fitting procedure; trigger efficiency; acceptance control; background shape; electron identification; radiative correction 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 37 /53

Scattering lengths result 2 parameter fit (correlation 0.967) a0 = 0.2220  0.0128(stat)  0.0050(syst) 0.0037(th*) a2 = - 0.0432  0.0086(stat)  0.0034(syst) 0.0028(th*) 1 parameter fit using ChPT link between a0 and a2 a0 = 0.2206  0.0049(stat)  0.0018(syst) 0.0064(th*) * Theoretical errors evaluated from isospin corrections & inputs to Roy equations numerical solution CGR EPJ C59 (2009) 777 . Perfect agreement with theory prediction: a0 = 0.220  0.005 a2 = - 0.0444  0.0010 CGL NP B603(2001), PRL 86 (2001) 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 38 /53

Cusp effect in K → p p0p0 60 M decays The measurements of: pion-pion scattering lengths: (a0 – a2) and a2 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 39 /53

“cusp effect” in K3pi decay 103 M(3) spectrum a clear change of slope (“cusp”) at +– threshold is observed. M2(00) spectrum Events background is negligible effect of K+– decays through charge exchange +–00: +– threshold M1 interferes destructively with M0 for M00<2m+ 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 40 /53

Cusp-effect: theory Original explanation: +–00 rescattering amplitude, depends on a0–a2 Cabibbo, PRL 93 (2004) 121801 Predicted: Budini, Fonda, PRL6(1961)419 Cabibbo-Isidori theory (2) More complete computation: Cabibbo, Isidori, JHEP 503(2005)21: other amplitudes: +–+–, +0+0, etc. two-loop O(ai2) corrections. provides sensitivity to a2 alone. Arbitrary scale Cusp point No rescattering amplitude Subleading effect Leading effect (3) The “Bern-Bonn” group description: Colangelo et al., PLB638 (2006) 187; Bissinger et al., PLB659(2008)576; NPB806(2009)178: effective non-relativistic Lagrangian; simultaneous fit of charged and neutral K3 modes; electromagnetic and radiative corrections included. 0.072 0.074 0.076 0.078 0.080 0.082 M2(00), (GeV/c2)2 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 41 /53

Fit to M2(00) spectrum Fit quality & pionium signature (Data–MC)/Data 7 data bins skipped around the M(+–) threshold Combined 2003+2004 sample Excess of events in the excluded interval, if interpreted as due to pionium decaying as A200, gives R=(K+A2)/(K+–) = (1.820.21)10–5. Prediction [Z.K. Silagadze, JETP Lett. 60 (1994) 689]: R=0.810–5 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 42 /53

Result of fit to M2(00) spectrum parameters: a0–a2, a2, Dalitz plot slopes, normalization (fit also includes K+– decays) with rad.corrections without rad.corrections ChPT constraint (statistical error only) a2m+ (a0–a2)m+ (a0–a2)m+ = 0.25710.0048stat. 0.0025syst. 0.0014ext. a2m+=–0.024  0.013stat. 0.009syst. 0.002ext. with ChPT constraint: (a0–a2)m+ = 0.2633  0.0024stat  0.0014syst  0.0019ext ChPT prediction: (a0–a2)m+ = 0.265  0.004 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 43 /53

pion-pion scattering lengths: summary of measurements in Ke4 and K3pi decays 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 44 /53

(a0, a2) measurements: summary Combination of NA48 measurements  Vs M , rad NA48/2 S118 E865 measurement is consistent with NA48/2 after erratum published: PRD81 (2010) 119903 E865 M, GeV NA48/2: two independent measurements with different samples, theory and systematics for the first time, good sensitivity to a2 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 45 /53

Comparison with other measurements of a0 BNL E865 (2010) ChPT prediction: a0=0.2200.005 Comparison with other measurements of a0 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 46 /53

(precise tests of ChPT) Rare decays of K (precise tests of ChPT) 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 47 /53

K → p p0 g EPJ C68 (2010)75 3 terms: IB, DE & INT IB INT DE contributing to the decay could be disentangled in W spectra (integrated over T*p) IB DE IB INT DE Likelihood fit to W spectra: r=- 0.93 600k decays Frac(DE) = (3.32 ± 0.15stat ± 0.14syst) ·10-2 Frac(INT) =(-2.35 ± 0.35stat ± 0.39syst) ·10-2 First evidense of nonzero INT contribution 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 48 /53

Br(K → p gg) Sensitive to O(p4) & O(p6) contributions. 1164 events selected 40 times more than the world sample 3% Bkg mainly from p p0 g Normalization — K2p (~6 M) Main systematics : acceptance Preliminary: Br = (1.07  0.04stat  0.08syst) 10-6 Last measurement: BNL E787(1991): 31 candidates, 5 BG events: BR = (1.10  0.32) 10-6 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 49 /53

NA62 (recommended at CERN SPS) Super rare CP-violating K decays K decays 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 50 /53

– clear test of SM sensitive to New Physics NA62:  decay – clear test of SM sensitive to New Physics Flavor Changing Neutral Current loop process: sd coupling & highest CKM suppression hadronic matrix element can be extracted from measured quantities of Ke3 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 51 /53

NA62 The bar for future NA62 SM E787/949 (6 ev) Br=(1.73 +1.13 –1.05) ×10-10 100 events Mean: E787/949 NA62 SM 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 52 /53

Conclusions kaons still provide variety of physics tasks for the research & have high potential of interesting discoveries the corresponding uptodate experiments require the development of frontier technology in detectors 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 53 /53

Дорогой Игорь Алексеевич ! Спасибо за мои первые шаги ! Поздравляю с Юбилеем !

Дорогой Игорь Алексеевич! Спасибо за мои первые шаги! Поздравляю с Юбилеем!

Spare 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 2 /36

Выводы Распады каонов дают уникальную возможность как для изучения - фундаментальных вопросов физики частиц настройки и проверки вопросов КХД низких знергий Экспериментальная физика каонных распадов — раздел физики частиц, занятый преодолением предела интенсивности событий («intensity frontier» - D. Bryman, KAON2009) и, соответственно, предела точности 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 2 /36

Scattering matrix: S|>=exp(2i)|> parameterized by 2 phases: 0,2 = –a0,2k + O(k2) S-wave scattering lengths a0, a2 are essential low-energy parameters of Chiral Perturbation Theory (ChPT).

Roy equations (unitarity, analyticity & crossing symmetry) Fit procedure the FF &  are extracted minimazing a log-likehood estimator in each of: Evts/bin evts MC Data 9.8 M 650 17.7 M 1180 411000 27 739500 49 K- K+ 10(M)x5(Me)x5(cose)x5(cos)x12() =15 000 equi-populated bins in each bin the correlation between the 4+1 parameters is taken into account. Roy equations (unitarity, analyticity & crossing symmetry) numerical solutions compute phases from data using a0 and a2 in the isospin symmetry limit Isospin corrections are evaluated as a correction to phase differences [CGR EPJ C59(2009)777] Radiative effects are included in simulation — Gamov factor (p+p- Coloumb attraction) in matrix element & PHOTOS generator for real photons emission 7 декабря 2010 В. Кекелидзе, юбилей И.А.Савина 2 /36