Measurement of Ke 3 BR and Study of

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Measurement of Ke 3 BR and Study of K→µνγ Decay at ISTRA+ SETUP INR/IHEP

Measurement of Ke 3 BR and Study of K→µνγ Decay at ISTRA+ SETUP INR/IHEP Protvino-Moscow, Russia Viacheslav Duk INR RAS KAON 2007

Contents 1. Experimental setup 2. K→µνγ @ ISTRA+: 2. 1 Event selection 2. 2

Contents 1. Experimental setup 2. K→µνγ @ ISTRA+: 2. 1 Event selection 2. 2 BR measurement 2. 3 Comparison with other experiments 3. K→eνπ0 @ ISTRA+: 3. 1 Vus and Ke 3 decay 3. 2 Event selection 3. 3 BR measurement 3. 4 Vus extraction 4. Conclusions

ISTRA+ experimental setup (U-70, Protvino) for studying rare kaon decays C 1 -C 4

ISTRA+ experimental setup (U-70, Protvino) for studying rare kaon decays C 1 -C 4 – thresh. cherenkov counters; S 1 -S 5 – scintillation counters; PC 1 -PC 3 – proportional chambers; SP 2 – veto calorimeter; SP 1 – lead-glass calorimeter; DC – drift chambers; DT-drift tubes; MH – matrix scintilation godoscope

The Study of K→ µ ν γ Decay at ISTRA+ Setup

The Study of K→ µ ν γ Decay at ISTRA+ Setup

K→ µ ν γ : Theory Differential decay rate : 3 main terms: IB

K→ µ ν γ : Theory Differential decay rate : 3 main terms: IB – dominant SD±, INT± - most interesting (→ Fv , FA) Kinematical variables: x=2*Eγ(cm)/Mk y=2*Eµ(cm)/Mk

K→ µ ν γ at ISTRA+ setup • Event Selection: • • 1 charged

K→ µ ν γ at ISTRA+ setup • Event Selection: • • 1 charged track Muon flag in HCAL 1 shower in ECAL (not associated with charged track) 300 cm < Zvertex < 1650 cm

K→ µ ν γ at ISTRA+ setup • Event Selection: • • 1 charged

K→ µ ν γ at ISTRA+ setup • Event Selection: • • 1 charged track Muon flag in HCAL 1 shower in ECAL (not associated with charged track) 300 cm < Zvertex < 1650 cm • Additional cuts: • Missing energy > 1 Ge. V • SP 2 veto • missing momentum points to ECAL aperture

K→ µ ν γ : background suppression • Main background: • K→ µ ν

K→ µ ν γ : background suppression • Main background: • K→ µ ν π0 (Kµ 3) with 1 gamma lost (from π0→γγ) • K→ π π0 (Kπ2) with 1 gamma lost (from π0→γγ) and π misidentification

K→ µ ν γ : background suppression • Main background: • K→ µ ν

K→ µ ν γ : background suppression • Main background: • K→ µ ν π0 (Kµ 3) with 1 gamma lost (from π0→γγ) • K→ π π0 (Kπ2) with 1 gamma lost (from π0→γγ) and π misidentification • Signal observation: M(µ ν γ)=√(Pµ+Pν+Pγ)2 where pν=pk-pµ-pγ ; Eν=|pν| M(µ ν γ) peaks at 0. 494 for signal

K→ µ ν γ : background suppression • Main background: • K→ µ ν

K→ µ ν γ : background suppression • Main background: • K→ µ ν π0 (Kµ 3) with 1 gamma lost (from π0→γγ) • K→ π π0 (Kπ2) with 1 gamma lost (from π0→γγ) and π misidentification • Signal observation: Signal M(µ ν γ)=√(Pµ+Pν+Pγ)2 where peak in (x, y) bin pν=pk-pµ-pγ ; Eν=|pν| M(µ ν γ) peaks at 0. 494 for signal Background rejection procedure: scanning over (x, y) Dalits-plot and fitting cosθµγ in selected bins M(µ ν γ)

K→ µ ν γ: selected kinematical region Eγ Eµ 140 -150 150 -160 160

K→ µ ν γ: selected kinematical region Eγ Eµ 140 -150 150 -160 160 -170 170 -180 130 -140 120 -130 110 -120 100 -110 90 -100 80 -90 70 -80 60 -70 50 -60 40 -50 30 -40 data - black MC - green 20 -30 10 -20 cosθµγ in selected region 180 -190 190 -200 200 -210 210 -220 220 -230 230 -240

K→ µ ν γ: Dalits-plot for signal, Kµ 3 and Kπ2 x x x

K→ µ ν γ: Dalits-plot for signal, Kµ 3 and Kπ2 x x x Kµ 3 (MC) Signal (MC) Kπ2 (MC) y y x Signal peak in (x, y) bin y Experimental Dalits-plot after event selection and preliminary cuts Real data Selected bins (signal peak in M (µ ν γ) ) M(µ ν γ) y

K→ µ ν γ: measured BR – preliminary results • • • 21500 events

K→ µ ν γ: measured BR – preliminary results • • • 21500 events of K→ µ ν γ observed BR(K→ µ ν γ)/BR(Kµ 3) is measured Supposing BR(Kµ 3)=(3. 32± 0. 06)x 10 -2 (PDG 06) BR(K→µ ν γ)=[1. 11± 0. 02(stat)± 0. 07(syst)]x 10 -3 Region: 40< Eγ <130 Me. V 150<Eµ<220 Me. V Theory: BR(K→ µ ν γ)~1. 03 x 10 -3

K→ µ ν γ: searching for INT and SD terms Dalits-plot for different terms

K→ µ ν γ: searching for INT and SD terms Dalits-plot for different terms x x x INT- INT+ IB y x y y x SD+ SD- y y

K→ µ ν γ: searching for INT and SD terms Dalits-plot for different terms

K→ µ ν γ: searching for INT and SD terms Dalits-plot for different terms x x x INT- INT+ IB y x y Our region is sensitive both to INT+ and INT- terms Detailed analysis is in progress y x SD+ SD- y y

K→ µ ν γ: comparison with other experiments Main experiments: KEK: Akiba et al,

K→ µ ν γ: comparison with other experiments Main experiments: KEK: Akiba et al, 1985 BNL: E 787, 2000 ISTRA+: 2007 x E 787(BNL) KEK ISTRA+ y

The Study of K→ e ν 0 π Decay at ISTRA+ Setup

The Study of K→ e ν 0 π Decay at ISTRA+ Setup

Motivation for Ke 3: Vus measurement; CKM unitarity test Vij - fundamental SM parameters

Motivation for Ke 3: Vus measurement; CKM unitarity test Vij - fundamental SM parameters CKM - quark mixing matrix VCKM = precise determination is important

Motivation for Ke 3: Vus measurement; CKM unitarity test Vij - fundamental SM parameters

Motivation for Ke 3: Vus measurement; CKM unitarity test Vij - fundamental SM parameters CKM - quark mixing matrix VCKM = precise determination is important CKM unitarity: VV+=1 Ø Testing SM Ø Probing New Physics (or constraining it)

Motivation for Ke 3: Vus measurement; CKM unitarity test Vij - fundamental SM parameters

Motivation for Ke 3: Vus measurement; CKM unitarity test Vij - fundamental SM parameters CKM - quark mixing matrix VCKM = precise determination is important CKM unitarity: VV+=1 Best unitarity test: |Vud|2+|Vus|2+|Vub|2=1 -δ q Processes are easy for theoretical description q Precise measurements are possible Ø Testing SM Ø Probing New Physics (or constraining it)

Vus from charged kaon decay K→eνπ0 (Ke 3)

Vus from charged kaon decay K→eνπ0 (Ke 3)

Vus from charged kaon decay K→eνπ0 (Ke 3) Theoretical inputs SEW=1. 0232(3) – short-distance

Vus from charged kaon decay K→eνπ0 (Ke 3) Theoretical inputs SEW=1. 0232(3) – short-distance radiative correction δSU 2 =(2. 3± 0. 2)*10 -2 - SU(2) breaking correction δe+=(0. 03± 0. 10)*10 -2 – long-distance QED correction f+(0) =0. 961± 0. 008 – form factor Main uncertainties are from f+(0)

Vus from charged kaon decay K→eνπ0 (Ke 3) Experimental inputs BR(Ke 3) τ(K±) f

Vus from charged kaon decay K→eνπ0 (Ke 3) Experimental inputs BR(Ke 3) τ(K±) f +(t) ISTRA+ 2007 PDG 06 ISTRA+ 2004 Theoretical inputs SEW=1. 0232(3) – short-distance radiative correction δSU 2 =(2. 3± 0. 2)*10 -2 - SU(2) breaking correction δe+=(0. 03± 0. 10)*10 -2 – long-distance QED correction f+(0) =0. 961± 0. 008 – form factor Main uncertainties are from f+(0)

K→ e ν π0 : event selection and backgrounds New approach to BR measurement:

K→ e ν π0 : event selection and backgrounds New approach to BR measurement: E/p 1 charged track events are selected E/p is used for e- identification Ke 3 is the dominant source for MC for Ke 3 and backgrounds events with 1 inclusive e- (<0. 1% for other decay modes) Normalization on Kπ2 decay Pπ(cm) Fitting E/p Ke 3 event number Fitting Pπ(cm) Kπ2 event number Pπ(cm) – charged track momentum assuming pion hypothesis in c. m. s. MC for Kπ2 and backgrounds

K→ e ν π0 : results N(Ke 3)=(2. 1739± 0. 0024)x 106 N(Kπ2)=(10. 2940±

K→ e ν π0 : results N(Ke 3)=(2. 1739± 0. 0024)x 106 N(Kπ2)=(10. 2940± 0. 0023)x 106 BR(Ke 3)/BR(Kπ2) is measured; using PDG 06 value for BR(Kπ2) E/p Pπ(cm) Experimental data – final fit BR(Ke 3)/BR(Kπ2)=0. 2449± 0. 0004(stat)± 0. 0014(syst) BR(Ke 3)=[5. 124± 0. 009(stat)± 0. 029(norm) ± 0. 030(syst)]x 10 -2 |Vus f+(0)|=0. 2186± 0. 0009(BR)± 0. 0012(th) |Vus|=0. 2275± 0. 0009(BR)± 0. 0022(th) δ=(-0. 03± 16)x 10 -4 Good agreement with other experiments

Conclusions • First observation of K→ µ ν γ in decays in flight and

Conclusions • First observation of K→ µ ν γ in decays in flight and in a new kinematical region • 21500 events of K→ µ ν γ observed (the largest statistics) • BR(K→ µ ν γ) = [1. 11± 0. 02(stat)± 0. 07(syst)]x 10 -3 Region: 40< Eγ <130 Me. V 150<Eµ<220 Me. V Theory: BR(K→ µ ν γ)~1. 03 x 10 -3 • Extraction of INT terms is in progress

Conclusions • new approach to Ke 3 study • 2 M events of Ke

Conclusions • new approach to Ke 3 study • 2 M events of Ke 3 extracted (the largest statistics) • BR(Ke 3) = [5. 124± 0. 009(stat)± 0. 029(norm) ± 0. 030(stat)]x 10 -3 • |Vus f+(0)|=0. 2186± 0. 0009(BR)± 0. 0012(th) • |Vus|=0. 2275± 0. 0009(BR)± 0. 0022(th)

Acknowledgments ISTRA+ work is supported by: - RFBR grants № 07 -02 -00957(IHEP) and

Acknowledgments ISTRA+ work is supported by: - RFBR grants № 07 -02 -00957(IHEP) and № 07 -02 -16065(INR) - Russian Science Support Foundation (INR)