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transcript
Giuseppe Ruggiero 1
๐ ๐ form factor and
๐ฒ+ โ ๐ +๐ ๐ at NA62
Giuseppe Ruggiero (CERN)
51 st Rencontres de Moriond EW 2016
La Thuile, 13/03/2016
13/03/2016
Outline
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Measurement of the ๐0 transition form factor on 2007 data.
Status and prospects for ๐พ+ โ ๐+๐ ๐.
Kaon @ CERN - SPS
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โ97-โ01 NA48: eโ/e
โ02 NA48/1: KS rare decays
โ03-โ04 NA48/2: Kยฑ CP violation, semileptonic, low energy QCD
โ07-โ08 NA62: Lepton universality (using the NA48 apparatus)
โ14 - NA62: ๐พ+ โ ๐+๐ ๐โข Installation completeโข Runs in 2014 - 2015โข Detector commissioningโข Data quality studies
LHC
NA48/62
SPS
Giuseppe Ruggiero 4
Kยฑ beams:PK = 75 ยฑ 2 GeV/c
Main Detectors (NA48):
Magnetic Spectrometer: s(P)/P = 0.48% 0.009 P(GeV/c)%
Hodoscope: Fast trigger for charged particles and timing for the event (s(t) = 200 ps)
Liquid Kripton e.m. calorimeter (LKr): s(E)/E = 3.2%/E 9%/E 0.42% (GeV)
NA62 2007 Layout
13/03/2016
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TFF measurement: test prediction from theoretical models
TFF models used for the hadronic light by light scattering contribution to ๐ โ 2 ๐
ฮด x radiativecorrection
NA62 2007 data
Data taking conditions optimized for Kยฑ โ eยฑฮฝ [Phys. Lett. B 719 (2013) 326]
Kยฑ โ ฯยฑฯ0, ฯ0 โ ฮณe+eโ
๐ ๐ โ ๐ธ๐ธโ Transition Form Factor
๐ ๐ โ ๐ธ๐+๐โ TFF: Selection
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Selection: 3-track topology, photon in LKr, full kinematic closure, x > 0.01
1.05 ร 106 fully reconstructed ฯ0 โ ฮณe+eโ
TFF obtained by adjusting the simulation to the data x spectrum.
๐ ๐ โ ๐ธ๐+๐โ TFF: Preliminary Result
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a = 3.70 ยฑ 0.53stat ยฑ 0.36syst ร 10โ2
TFF Theory expectations:
a = 2.90 ยฑ 0.50 ร 10โ2, PT, [K. Kampf et al. EPJ C46 (2006), 191]
a = 3.07 ยฑ 0.06 ร 10โ2, dispersion theory, [M. Hoferichter et al. EPJ C74 (2014), 3180]
a = 2.92 ยฑ 0.04 ร 10โ2, two-hadron saturation, [T. Husek et al. EPJ C75 (2015) 12, 586]
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The ๐ฒ โ ๐ ๐ ๐ decays: a theoretical clean environment
FCNC loop processes: sd coupling and highest CKM suppression
13/03/2016
Very clean theoretically: Short distance contribution. No hadronic uncertainties.
SM predictions [Buras et al. arXiv:1503.02693], [Brod, Gorbahn, Stamou, Phys. Rev.D 83, 034030 (2011)]
BR ๐พ+ โ ๐+๐ ๐ = 8.39 ยฑ 0.30 โ 10โ11๐๐๐
0.0407
2.8๐พ
73.2ยฐ
0.74
= 8.4 ยฑ 1.0 โ 10โ11
BR ๐พ๐ฟ โ ๐0๐ ๐ = 3.36 ยฑ 0.05 โ 10โ11๐๐ข๐
0.00388
2๐๐๐
0.0407
2sin ๐พ
sin 73.2
2
= 3.4 ยฑ 0.6 โ 10โ11
Experiments:
BR K+ โ ฯ+ฮฝ ฮฝ = 17.3โ10.5+11.5 ร 10โ11
BR KL โ ฯ0ฮฝ ฮฝ < 2.6 ร 10โ8 (90% C. L. )
Phys. Rev. D 77, 052003 (2008), Phys. Rev. D 79, 092004 (2009)
Phys. Rev. D 81, 072004 (2010)
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๐ฒ โ ๐ ๐ ๐ NP Sensitivity
Simplified Z, Zโ models [Buras, Buttazzo,Knegjens, arXiv:1507.08672 (2015)]
Littlest Higgs with T-parity [Blanke, Buras, Recksiegel, arXiv:1507.06316 (2015)]
Custodial Randall-Sundrum [Blanke, Buras, Duling, Gemmler, Gori, JHEP 0903 (2009) 108]
MSSM non-MFV [Tanimoto, Yamamoto arXiv:1503.06270, Isidori et al. JHEP 0608 (2006) 064 ]
Constraints from existing measurements (correlations model dependent):
Kaon mixing and CPV, CKM fit, K,B rare meson decays, NP limits from direct searches
Zโ model Randall - Sundrum Littlest Higgs
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The NA62 Experiment for ๐ฒ+ โ ๐ +๐ ๐
Primary goal:
10% precision BR(๐พ+ โ ๐+๐ ๐)
Requirements:
Statistics: O(100) events
K decays (2 years) 1013 , Signal acceptance 10%
Systematics: <10% precision background measurement
>1012 background rejection (<20% background)
Technique:
K Decay โ in โ flight
13/03/2016
Birmingham, Bratislava, Bristol, Bucharest, CERN, Dubna (JINR), Fairfax, Ferrara, Florence, Frascati, Glasgow, Liverpool, Louvain-la-Neuve, Mainz, Merced, Moscow (INR), Naples, Perugia, Pisa, Prague, Protvino (IHEP) , Rome I, Rome II, San Luis Potosi, SLAC, Sofia, TRIUMF, Turin, Vancouver (UBC)
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NA62 Apparatus
13/03/2016
SPS proton400 GeV1012 p/s3.5 s spill
Secondary Beam75 GeV c , โp/p~1%X,Y Divergence < 100 mradK 6% ,ฯ 70% , p 23%Total rate: 750 MHzBeam size: 6.0 ร 2.7 cm2
Kaon Decay~5 MHz4.5 ร 1012/๐ฆ๐๐๐60 m length10โ6 mbar vacuum
Detectors for decay productsCharged particle trackingCharged particle time stampingPhoton detectionParticle ID
Detectors for Secondary BeamKaon ID (KTAG)Beam TrackerBeam guard ring (CHANTI)
target
Momentum selection &collimation
KTAG Beam tracker
E.M.calorimeters(large angles)
E.M.calorimeter(forward)
E.M. calorimeters(small angles)
Hadroncalorimeter
RICH
StrawSpectrometer~150 m~100 m
1 m CHANTI
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Experimental StatusNA62 took data in 2014 and 2015
Beam commissioned up to nominal intensity
Tracker:
Beam tracker (Gigatracker) partially commissioned.
Straw spectrometer commissioned
Cherenkov detectors:
Beam Kaon ID (KTAG) commissioned.
RICH commissioned.
All the other detectors commissioned
Trigger:
L0 commissioned; L1(2) partially commissioned.
Data samples for data quality study (mainly from 2015):
Low intensity data taken with a minimum bias trigger (this talk).
Samples at half and full intensity taken with a calorimeter trigger.
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Scheme for ๐ฒ+ โ ๐ +๐ ๐ Analysis
13/03/2016
Background: K+ decay modes; beam activity
Experimental principles:
1) Precise kinematic reconstruction
2) PID: K upstream, ๐ ๐ ๐ downstream
3) Hermetic ๐พ detection
4) Sub-ns timing
Signal
Key analysis requirements
2 signal regions in ๐๐๐๐ ๐ 2
15 < ๐๐ < 35 GeV/c
65 m long decay region
theoretical shapes
Kinematics: mmiss2 = PK โ Pฯ+
2
Expected 45 SM signal events / year with < 10 background [O(10โ12) SES]
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Signal Topology and Kaon ID
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Kaon IDTrack origin in the fiducial region
One โ track selection (OTS)
Single downstream track topology
Beam track matching the downstream track
Beam track matching a K signal in Kaon ID
Downstream track matching energy in calorimeters
Time resolutions:
Kaon ID < 100 ps
Beam track < 200 ps
Downstream track < 200 ps
Calorimeters 1-2 ns
Beam activity
2015 data
K decay
2015 data
2015 data
OTS + not Kaon ID
OTS + Kaon ID + Vertex cut
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Technique: Si - pixel tracker; Straw tube tracker in vacuum
Goal: O(104 รท 105) suppression factor of the main kaon decay modes
๐๐+ < 35 GeV/c: best ๐พ+ โ ๐+๐ suppression.
Kinematics studied on ๐พ+ โ ๐+๐0 selected using LKr calorimeter.
Resolutions close to the design.
O(103) kinematic suppression factor in 2015.
K decayK+ โ ฯ+ฯ0
K+ โ ฮผ+ฮฝ
K+ โ 3ฯ
K+ โ ฯ0l+ฮฝ
2015 data
2015 data
OTS + Kaon ID + Vertex cutKinematics
Downstream Particle Identification
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Technique: RICH and calorimeters
Goal: O(107) m/p separation to suppress mainly ๐พ+ โ ๐+๐
15 < ๐๐+ < 35 GeV/c: best m/p separation in RICH
Pure samples of pions and muons selected using kinematics
RICH: O(102) p/m separation, 80% ๐+efficiency in 2015.
Calorimeters: 104 รท 106 ๐ suppression, 90% รท 40% ๐+efficiency in 2015 using a cut analysis. Room for improvements.
OTS
๐+๐+ ๐พ+
๐+
2015 data
15 < Pฯ+ < 35 GeV/c
RICH
2015 data
RICH
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Technique: EM calorimeters exploiting correlations between gsโ from ๐0.
Goal: O(108) rejection p0 from K+p+p0
Pฯ+ < 35 GeV/c Eฯ0 > 40 GeV
Measured on data using K+p+p0
selected kinematically
2015 measurement statistically limited
Photon rejection
calorimeters(large angles)
calorimeter(forward)
calorimeter(small angles)
15 < Pฯ+ < Pฯ+MAX
2015 data
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Summary from (low intensity) data
quality studies
13/03/2016
1) Time resolution
Close to the design
2) Kinematics
Resolution close to the design.
Prospects to reach the designed signal โ background separation.
3) Pion โ muon ID
Separation with RICH close to expectations.
Study of the separation with calorimeters on going. Results from simple cut analysis promising.
4) Photon veto:
O(106) ๐0 rejection already obtained. More statistics needed to push the study at the design sensitivity.
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Further NA62 Physics Program
13/03/2016
Standard Kaon Physics
Precision measurements of the branching ratio of all the main K decay modes
๐PT studies: ๐พ+ โ ๐+๐พ๐พ, ๐พ+ โ ๐+๐0๐+๐โ, ๐พ+ โ ๐0(+)๐0(โ)๐+๐
LU study with the precision measurement of ๐ ๐พ = ฮ(๐พ+ โ ๐+๐) ฮ(๐พ+ โ ๐+๐)
LFV with Kaons:
๐พ+ โ ๐+๐ยฑ๐โ, ๐พ+ โ ๐โ๐+๐+, ๐พ+ โ ๐โ๐+๐+
Heavy neutrino searches:
K+ โ l+ฮฝhฮฝh from K, D decays and ๐โ โ ๐๐
ฯ0 decays:
ฯ0 โ invisible, ๐0 โ 3/4๐พ, ๐0 โ ๐๐พ
Dark sector searches:
Long living dark photon decaying in ๐+๐โ and produced by ๐0 ๐ ๐โฒ ฮฆ ๐ ๐ decays
Long living axion-like decaying in gg produced in a beam-dump configuration
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NA62 and Heavy Neutrino
13/03/2016
Search for heavy neutrinos produced in K+ โ ฮผ+๐โand K+ โ e+๐โNA62 is perfectly suited to search for ๐โ in 100 โ 380 MeV c2 mass range:
K+ โ l+๐โ decays kinematically enhanced wrt to K+ โ ฮผ+๐๐๐Background in the mass region search ~5 order of magnitude below the K+ โ l+๐๐๐ peak
Mass search
window
Pฮผ โ PK2
GeV2 c4
2015 data
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Conclusions
13/03/2016
Preliminary world best measurement of the ๐0 transition form factor slope (NA62 2007 data):
The NA62 experiment for ๐พ+ โ ๐+๐ ๐ commissioned. Tested up to nominal intensity
Preliminary study of the quality of the data taken at low intensity:
Physics sensitivity for ๐พ+ โ ๐+๐ ๐ measurement in line with the design.
A further compelling physics program is going to be addressed.
Analysis of data at higher intensity on going.
NA62 will resume data taking end of April 2016 (~200 days run in 2016).
a = 3.70 ยฑ 0.53stat ยฑ 0.36syst ร 10โ2 = (3.70 ยฑ 0.64) ร 10โ2