STUDY OF ULTRAREAR DECAYS K 0 → π 0 νν(bar) (Search of K 0 → π 0 νν(bar) decay at IHEP,...

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STUDY OF ULTRAREAR DECAYS K 0 π 0 νν(bar) (Search of K 0 → π 0 νν(bar) decay at IHEP , project KLOD ) V.N. Bolotov on behalf of the collaboration JINR, IHEP and INR RAS

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STUDY OF ULTRAREAR DECAYS K 0 0 (bar) (Search of K 0 0 (bar) decay at IHEP, project KLOD ) V.N. Bolotov on behalf of the collaboration JINR, IHEP and INR RAS Slide 2 29.11.20152 Slide 3 3 STATE RESEARCH CENTER OF RUSSIA INSTITUTE FOR HIGH ENERGY PHYSICS Slide 4 29.11.20154 theoretically Rare FCNC process Purely CP-Violetting (Littenberg, 1989) Totally dominated from t-quark Computed in QCD (Buchalla, Buras, 1999) Small corrections due to m t is known from K + 0 e + e (K e3 ) No long distance contribution (Rein, L. M. Sehgal, 1989; Marciano, Z. Parsa 1996) SM: Br ~ 2, CP violating parameter (Buchalla, Buras, PR, 1996) Sensitive to the new heavy objects New physics Theoretically clean process, ~1% SM: Br = (2.80.4)10 11 (Buras et al., hep-ph/0603079) Slide 5 29.11.20155 Slide 6 6 Slide 7 7 Slide 8 8 Slide 9 9 Slide 10 10 Experimental challenge. Must-do experiment signature: 0 -signal + nothing At least 2 charged or 4 s -- veto inefficiency ~ 10 -6 -- full veto covered 0 in 34% of decays -- P T cut (231MeV/c) Interaction with gas -- high vacuum Strategy: 2 s in Ecal No veto-signal Construct 0 from 2 s -- reconstruct vertex -- reconstruct P T (narrow beam approach) Slide 11 29.11.201511 K L beam at U-70 IHEP Beam requirements -- very narrow (R 29.11.201524 In Beam Veto Calorimeter 1-st idea :to use Cherenkov light quartz fibers are only sensitive to em shower component CMS HF: e/h ~ 5, NIM A399 (1997) 202 2-nd idea: Dual Readout (Scint.+Ch.) DREAM calorimeter, NIM A536 (2005) 29 Purpose is to measure f em event by event & eliminate dominant source of fluctuations for hadrons. They succeed ! Hadron Blind Calorimeter ? Not our goal ! But... -- look at Ch/Sc signals ratio & its behavior in transverse and longitudinal directions Possible problem : not enough Ch. light => 45 deg. turn => more quartz fibers (more loose structure) The goal is not to measure E but to identify s Not Hadron-Blind but Hadron-Distinguishable Calorimeter Suitable for our goal prototype is under construction Slide 25 In Beam Veto Calorimeter 1-st idea :to use Cherenkov light quartz fibers are only sensitive to em shower component CMS HF: e/h ~ 5, NIM A399 (1997) 202 2-nd idea: Dual Readout (Scint.+Ch.) DREAM calorimeter, NIM A536 (2005) 29 Purpose is to measure f em event by event & eliminate dominant source of fluctuations for hadrons. They succeed ! Hadron Blind Calorimeter ? Not our goal ! But... -- look at Ch/Sc signals ratio & its behavior in transverse and longitudinal directions Possible problem : not enough Ch. light => 45 deg. turn => more quartz fibers (more loose structure) The goal is not to measure E but to identify s Not Hadron-Blind but Hadron-Distinguishable Calorimeter Suitable for our goal prototype is under construction Slide 26 29.11.201526 In Beam Veto Calorimeter 1-st idea :to use Cherenkov light quartz fibers are only sensitive to em shower component CMS HF: e/h ~ 5, NIM A399 (1997) 202 2-nd idea: Dual Readout (Scint.+Ch.) DREAM calorimeter, NIM A536 (2005) 29 Purpose is to measure f em event by event & eliminate dominant source of fluctuations for hadrons. They succeed ! Hadron Blind Calorimeter ? Not our goal ! But... -- look at Ch/Sc signals ratio & its behavior in transverse and longitudinal directions Possible problem : not enough Ch. light => 45 deg. turn => more quartz fibers (more loose structure) The goal is not to measure E but to identify s Not Hadron-Blind but Hadron-Distinguishable Calorimeter Suitable for our goal prototype is under construction Slide 27 29.11.201527 Monte-Carlo Resolutions -- (Z) 15 cm (without beam contribution) Dominated by FCal energy resolution -- (P T ) 6 MeV/c Defined by beam angular spread Slide 28 29.11.201528 For 1 SM decay K L 0.1 Br = 5.7 x 10 -4 K L 0 0 ~ 0.26 Br = 9.1 x 10 -4 Max(Pt)=209 /c K L 0 0 0 0.1 Br = 21.6% Max(Pt)=139 /c K L - + 0.1 Br = 38.7% Main cuts E (1), E (2) > 0.15 GeV better FCal performances, s from excitation E (1), E (2) < 6 GeV Pt > 120 MeV/c Reconstructed Vertex inside Main Decay Volume s pointed to the reconstructed Vertex (+/- 0.5 m) works for s not from one 0 Energy gravity Center > 20 cm from beam axis Dist(1-2) > 15 cm accidentals, s from different 0 s Background & Sensitivity Estimation Acceptance 18 (15) % 4.8% K L decays in Main Volume @ 10 8 (5.410 7 ) K L /spill 10 days sensitivity (~ 10 4 spills/day) 10(10 4 )( 10 8 )(4.810 -2 )(1.810 -1 )Br(2.810 -11 ) 2.4 events 10(10 4 )(5.410 7 )(4.810 -2 )(1.510 -1 )Br(2.810 -11 ) 1.1 events Slide 29 29.11.201529 For 1 SM decay K L 0.1 Br = 5.7 x 10 -4 K L 0 0 ~ 0.26 Br = 9.1 x 10 -4 Max(Pt)=209 /c K L 0 0 0 0.1 Br = 21.6% Max(Pt)=139 /c K L - + 0.1 Br = 38.7% Main cuts E (1), E (2) > 0.15 GeV better FCal performances, s from excitation E (1), E (2) < 6 GeV Pt > 120 MeV/c Reconstructed Vertex inside Main Decay Volume s pointed to the reconstructed Vertex (+/- 0.5 m) works for s not from one 0 Energy gravity Center > 20 cm from beam axis Dist(1-2) > 15 cm accidentals, s from different 0 s Background & Sensitivity Estimation Acceptance 18 (15) % 4.8% K L decays in Main Volume @ 10 8 (5.410 7 ) K L /spill 10 days sensitivity (~ 10 4 spills/day) 10(10 4 )( 10 8 )(4.810 -2 )(1.810 -1 )Br(2.810 -11 ) 2.4 events 10(10 4 )(5.410 7 )(4.810 -2 )(1.510 -1 )Br(2.810 -11 ) 1.1 events Slide 30 29.11.201530 Summary There is a possibility to make at IHEP setup for registration of K 0 0 decays. Sensitivity of setup allows for reasonable time (100 days) to register about 30 (SM) decays at a level of a background near 9 decays. R&D for production and test of prototypes of the basic detectors is necessary. The further simulation for more exact calculation of signals and background processes is necessary.