September 27, 2005Status Report, SPSC 1 Experiments NA48/1 & NA48/2 Status Report (SPSC-2005-031) CERN, Cambridge, Chicago, Dubna, Edinburgh, Ferrara,

September 27, 2005Status Report, SPSC

1

Experiments NA48/1 & NA48/2Experiments NA48/1 & NA48/2

Status Report (SPSC-2005-031)

CERN, Cambridge, Chicago, Dubna, Edinburgh, Ferrara, Firenze, Mainz, Northwestern, Perugia, Pisa, Saclay, Siegen, Torino, Vienna

Collaboration:

V.Kekelidze for


2

Content

Introduction Rare decays in the experiment NA48/1 Search for direct CP-violation in the NA48/2 Test of PT: precise measurement of

the - scattering length Rare decay of charged kaons Leptonic & semileptonic decays Summary & request


3

High Precision Study of Kaon & Hyperon Decays

Physics motivation for the experimentsPhysics motivation for the experiments

Search for new physics & tests of the SM High accuracy tests of low energy QCD (PT) Quantitative tests of various model predictions

• NA48/1 NA48/1

2000 Phase I (no spectrometer): KS & KL decays

2002 Phase II (high intensity run): KS & Hyperon decays

KS in fiducial volume: ~ 3.5 1010

• NA48/2 NA48/2 simultaneous K+ and K- beams

2003 – 2004 K in fiducial volume: > 2. 1011


4

Rare decays in Rare decays in the experiment the experiment

NA48/1NA48/1


5

Measurement of Br(KSe)

Br = (6.8 0.2stat 02sys)10-4

PDG value : (6.9 0.4)10-4

analysis finishedpaper preparationis in progress

is improved in precision~13’000


6

0+e+e decays

BR= (2.57 0.12stat +0.10 –0.09 syst)10-4

in good agreement withour measurement:

BR= (0+e-e)=(2.510.03stat 0.09syst)10-4


7

0+- decays

BR= (2.2 0.3stat 0.2 syst)10-6

102 decays32 3.0

background

most precise measurement

paper in preparation

KTEV:

(4.7+0.2-1.4 stat0.8sys)10-6


8

R= N(0)/ N(0) R= (9.31 0.05stat 0.04 syst)10-2

new (preliminary)

Br(KS + - 0) submitted to PRL


9

Search for direct Search for direct CP-violation CP-violation

in NA48/2in NA48/2


10

Direct CP violation

in K± ± ± , K± ± 0 0 M(u) 1 + gu, u = f( )

g = g+ - g- = 2Ag<g>

(Ag ) < 210 – 4 (limited by statistics)

GoalGoal

g + - g -

Ag = ———— g+ + g -

Requirements to experiment:

• high statistics (~ few109 decays)• stability in time• set –up symmetry

*

oddE


11

Measurements & predictions

10-6

|Ag|

Experimental precisions by 2005:Experimental precisions by 2005:

10-5

10-4

10-3

10-2

SMSM SUSYSUSYNewNew

physicsphysics

Ford et al. (1970)

HyperCP prelim. (2000)

TNF prelim. (2002)“neutral” mode

NA48/2proposal

SM estimates vary within an order of magnitude (few 10few 10-6-6……

8x108x10-5-5). Models beyond SM predict substantial

enhancement partially within the reach of NA48/2.

[[AAgg~10~10-3-3]]

“charged”“neutral”

Theory

Asymmetry in decay widthsexpected to be smaller than

in Dalitz-plot slopes(SM: ~10-7…10-6).


12

NA48/2 method

– Two simultaneous K+ and K– beams, superimposed in space, with narrow momentum spectra;

– Detect asymmetry exclusively considering slopes of ratios of normalized U distributions;

– Equalize K+ and K– acceptances by frequently alternating polarities of relevant magnets.


13

1cm

50 100

10 cm

200 250 m

vacuum tank

He tank+ spectrometer

magnetB+

K+

K-

K+

K-

NA48/2NA48/2 experiment configuration experiment configuration

114m decay volume

focusing beams

DFDFQuadrupole Quadruplet

beams coincide within <1mm

FDFD

FRONT-END ACHROMAT

PK spectra, 603 GeV/c

54 60 66

The simultaneous K+ and K- beams NA48 Set-Up

not to scale

TAX 17 TAX 18

~71011

ppp

2nd

ACHROMAT

BM

z


14

20032003 run:run: ~ 50 days~ 50 days(~ 1 month stable conditions)(~ 1 month stable conditions)

20042004 run: ~ 60 daysrun: ~ 60 days

~ ~ 200 TB of data recorded200 TB of data recorded

NA48/2NA48/2 runs runs


15

recorded events, 10 6 # of Super-Samples

Run K - + K 0 0 (complete cycles)

2003-I 670 20 SS0

2003-II 940 28 SS1-3

Statistics

data taken in 2004: calibrated, reprocessed & filtered

analysis started


16

Super-samples 2003Super-samples 2003

Dates Sub-samples

Achromat A+ Achromat A–

K+ K– K+ K–

0 22.06-25.07 26 229.6229.6 125.9125.9 201.0201.0 114.0114.0

1 6.08-20.08 12 122.5122.5 68.168.1 135.1135.1 75.475.4

2 20.08-3.09 12 147.2147.2 81.881.8 105.5105.5 58.958.9

3 3.09-7.09 4 40.640.6 22.622.6 54.554.5 30.430.4

Total 54 Total events selected 1613.2

Statistics selected for Ag measurement, events x106


17

Selected statistics 2003

U

|V|

even pionin beam pipe

Data-taking 2003: 1.61x101.61x1099 events selected

KK+ + : 1.03x10: 1.03x109 9 eventsevents

KK : 0.58x10: 0.58x109 9 eventsevents

odd pionin beam pipe

MM=1.7 MeV/c=1.7 MeV/c22

Events


18

Beam movement in time

X, cm

Y,

cm

DCH1(upstream magnet)

K+ K

X, cm Typical scales:• beam movement in time ~2mm• beam width ~5mm

Y,

cm

0 0.4 0.8-0.4-0.8

0

0.4

0.8

-0.4

-0.8

X, cm

Beam profile @DCH1(a small fraction of data)


19

Acceptance cancellation cancellation within a supersample

N(A+B+K+)N(A+B-K-)RUS=

Detector left-right asymmetry cancels in 4 ratios of KK++ over Kover K uu-spectra-spectra::

ZZ

XXYY

JuraJura

SSalevealeve

Achromats: KAchromats: K++ UUpp

Achromats: KAchromats: K++ Down Down

B+

B

Indexes of R’s correspond to• beamline polarity (U/D);• direction of kaon deviation in spectrometer magnet field (S/J)

• same deviation direction by spectrometer magnet in numerator and denominator;same deviation direction by spectrometer magnet in numerator and denominator;• data from 2 different time periods used at this stage.data from 2 different time periods used at this stage.

N(A+B-K+)N(A+B+K-)RUJ=

N(A-B+K+)N(A-B-K-)RDS=

N(A-B-K+)N(A-B+K-)RDJ=

R(u) = RUS RUJ RDS RDJ=N(1+4gu)


20

Example of fits: supersample 1

U

U

U

U

U

22=38.1/38=38.1/38

22=37.5/38=37.5/38 22=50.5/38=50.5/38

22=35.6/38=35.6/38 22=34.8/38=34.8/38

AAUS=(2.4=(2.4±4.6)x10±4.6)x10-4-4

AADS=(8.2=(8.2±4.4)x10±4.4)x10-4-4

AAUJJ=(-=(-0.20.2±4.6)x10±4.6)x10-4-4

AADJ=(-=(-1.01.0±4.4)x10±4.4)x10-4-4

=(2.3=(2.3±2.2)x10±2.2)x10-4-4R(u)/N


21

Time-stability (vs super-sample)Time-stability (vs super-sample)

0

5

10

15

20

-5

-10

-15

-20

x10-4

Monte-Carlo describeseffects of

permanent magnetic fieldsand differences of

beamline properties

(S-J)/2 (D-U)/2

left / right up / downset-up asymmetry:


22

Stability vs kinematic variablesStability vs kinematic variables

0

10

20

30

40

-10

-20

-30

-40

g x10-4

0

20

40

60

80

-20

-40

-60

-80

g x10-4


23

Result & systematicsConservative estimations

of systematic errors

Effect on

Δx104

Acceptance and beam geometry

0.5

Spectrometer alignment 0.1

Analyzing magnet field 0.1

π± decay 0.4

U calculation and fitting 0.5

Pile-up 0.3

Syst. errors of statistical nature

Trigger efficiency: L2 0.8

Trigger efficiency: L1 0.4

Total Total systematic error 1.31.3

Raw Corrected for L2 eff

SS0 0.0±1.5 0.5 ± 2.4

SS1 0.9±2.0 2.2 ± 2.2

SS2 -2.8 ± 2.2 -3.0 ± 2.5

SS3 2.0 ± 3.4 -2.6 ± 3.9

TotalTotal -0.2 ± 1.0 -0.2 ± 1.3

22 2.2 / 3 3.2 / 3

Combined result: Δx104

(3 independent analyses) L2 trigger systematics included


24

Preliminary result: 2003 dataPreliminary result: 2003 data

Slope difference:Δg = (-0.2±1.0stat.±0.9stat.(trig.)±0.9syst.)10-4 = (-0.2±1.7)10-4

Charge asymmetry:Ag = (0.5±2.4stat.±2.1stat.(trig.)±2.1syst.) 10-4 = (0.5±3.8)10-

4

• systematic errors are conservative for preliminary result

• better control of systematics in 2004 due to: - more frequent polarity alternation

- better L2 performance


25

specific features:one charged track (±) to measure

asymmetry

Lkr used for 0 0 identification

different acceptance (u) & large g0= 0.652 ± 0.033

Asymmetry in K± ± 0 0 preliminary result based on SS0-SS3 (~ 48 M decays)


26

K 00 + 4

m

reconstruction algorithm

pairs of ’s should have a common vertex compatible withkaon decay

E1E2 (d12)2

LKr


27

Reconstructed decays K± ± 0 0

K+

preliminary result based on SS0-SS3 (~ 48 M decays)

K-

~31M ~17M


28

Data analyzed: SS-0,-12,-3

g0 = (2.2 2.2 stat)10-4

u

uu

g1

g1N)(RCC

u

u

u

R(u), 10-4 SS0

SS12

SS3

R(u), 10-4

R(u), 10-4


29

Stability check & comparison with MC

left / right up / downset-up asymmetry:

MC

exper.

10-4

g0AS-AJ AU-AD


30

Stability checks of obtained g0

PK Vz

day sample|V|

10-4

10-4

g0

g0


31

Result (preliminary):

three analyses obtain very close results

A0g major systematics in 10-4 units: alignment (<

0.1) acceptance & beam geometry (< 0.1)

momentum scale (< 0.1)u-calculation & fit (< 0.4)

accidentals (< 1.0)L1 trigger (< 1.5), L2 trigger (< 0.4),

fit region (0.0025),LKr nonlinearity corrections (< 0.4)

A0g = (1.7 1.7stat 1.2trig 1.0syst 0.2extern)10-4


32

Test of Test of PT :PT :precise measurement of precise measurement of the the -- scattering length scattering length


33

Theory calculationpredicted by PT first principles (Weinberg 1966)G.Colangelo, J.Gasser, H.Leutwyler, NP B603(2001)125

scattering length

m + = - 0.0444 ± 0.001002a0

0a m + = 0.220 ± 0.00500a( - )

02a m += - 0.265±0.004 1.5%

Experimental measurements mesoatom lifetime (DIRAC) form-factors in Ke4 decays

for the first time: Geneva-Saclay (1977): 30,000 events

best measurement: BNL E865 (2001): 400,000 events

precision limited by statistics

00a| - |2

02a

= 0.216 ± 0.013stat ±0.002syst±0.002theor

00a m

~ 6 %

Statistics of NA48/2: > 1,000,000 Ke4 events


34

measurement of from K (3)

simple model: N. Cabibbo, P.L.B 93(2004)121801

A threshold effect in M(00) has been observed (cusp structure) for the first time in NA48/2 thanks to

high resolution in energy high statistics

collectedindication to the re-scattering of + - 0 0

in the decay K + - 0 0 is related to

00a( - )

02a

00a( - )

02aNew way !

two loops approximation: N.Cabibbo, G.Isidori, JHEP03(2005)021

(I symmetry is foreseen)introduce I-breaking parameter = (m+

2 - mo2)/m+

2 = 0.065 M.Knecht, R.Urech, N.P. B519(1998)329;

G. Colangelo,J.Gasser,B.Kubis,A.Rusetsky: Kaon Mini-workshop (CERN-05)


35

First Observation of the + - -thresholdin K M0 0 decays

M2(00), (GeV/c2)2 M2(00), (GeV/c2)2

4m2()= 0.0779(GeV/c2)2

~23M decays


36

Fit quality Simple Cabibbo model:

axm+ = (a0 - a2)m+/3

2/D.F. = 420.1 / 148

= data - MC

Cabibbo, Isidori: two loop approximation;I- breaking (1 parameter)

(a0 - a2)m+, a2m+ , g0 , h+ , N

2/D.F = 154.8 / 146

…..+ pionium (1.61 0.66)10-5

2/D.F.=149.1 / 145

consistent with Z.Silagadze calc: 0.810-5

exclude pionium region 2/D.F.=145.5 / 139


37

Results (paper in preparation):

two analysis (different MC & criteria) obtain very close results

m+ major systematics: acceptance (0.001)

trigger (0.001)fit region (0.0025)

LKr resolution & nonlinearity (0.001) track- separation (0.002)

taking into account uncertainty in theory ~ 5% (ext):

00a( - )

02a

m+ = 0.268 0.010stat 0.004syst 0.013ext

m+ = - 0.041 0.021stat 0.014syst

00a( - )

02a02a


38

m+ = 0.220 0.006stat 0.004syst 0.003R 0.011theor

m+= 0.264 0.006stat 0.004syst 0.003R 0.013theor

Results (continuation):

taking into account uncertainty in R= A ++- / A+00

& theoretical constrains between

experimental uncertainty < 3% - limited by statisticswhich will be increased using 2004 data by factor ~ 4

00a( - )

02a

00a

00a &

02a


39

K±+-e±ν (Ke4)

taking into account additional data (SS0 & 2004) it is expected in total:

> 1000k decays

background

selection:2003 data SS1-3: ~ 350k (background ~0.5%)

mproducts

expected precision in better than ±0.010stat

00a


40

Cabibbo-Maksymowicz variables

background

, e have opposite sign for

K+ & K- (T.D. Lee and C.S.Wu –1966)

d5K-(m,me,,e,)= d5K+ (m,m e,,-e,+)

- line of flight in K rest frame

both K+ and K- decays are accumulated at similar experimental conditions this allows to tests CP, and CPT (for the fist time)

and provide reliable cross checks for possible systematic ancertainties


41

Other Rare Decays Other Rare Decays of Charged Kaonsof Charged Kaons

SS1-3:~1 month of running in 2003


42

GoalsGoals

Rare decays to test PT & search for ACP

K , K 0 DE

K e+ e, K + , Ke2

K l l+l

K 0 , K 0 l+l, … etc.


43

K 0

PDG

T: 55 – 90 MeV

• Br=(2.750.15)10-4

DE contribution:• Br=(4.70.9)10-6

Interference term – possible source of

CPV

(order of magnitudehigher than others)


44

Z=(M(ee)/MK)2M(± e+e-), GeV/c2

Statistics comparable to the World best sample at low background (1-2%)

K±±e+e- & K±±+-

K± ± e+e-.Statistics > PDG

Analyses are ongoing: form-factors study


45

Leptonics & SemileptonicsLeptonics & Semileptonicsof Charged Kaonsof Charged Kaons

Special minimum-bias runs in 2003 & 2004


46

Goals Goals

Leptonics & Semileptonic decays:

Ke3, K

3

BR’s to improve precision of |Vus|

& check CKM unitarity,

check -e universality

form-factors to search for fT, fS


47

Results (preliminary)

• R(Ke3/K2) = 0.2505 0.0009stat 0.0012syst • R(K3/K2) = 0.1646 0.0006stat 0.0011syst • R(K3/Ke3) = 0.657 0.003stat 0.003syst

• R(Ke2/K2 )= 2.416 0.043stat 0.024syst 2003 run

• R(Ke2/K2 )= 2.453 0.046stat 0.026syst 2004 run

PDG = 2.45 0.11SM = 2.472 0.001


48

Summary & RequestSummary & Request

Special minimum-bias runs in 2003 & 2004


49

NA48/1 high precision results are obtained on Ks decays and hyperon

semileptonics, (analysis continues)

NA48/2 first results are obtained on charged asymmetry in both

K± ± +- and K± ± 00 decaysbased on 2003 data

achieved precision is limited by statistics


50

NA48/2NA48/2(cont.)

A “cusp” structure has been observed

for the first time in K 0 0 decays

which allows to high precision measurement

of - scattering length Large sample of both signs of K±e4

decays provides good opportunity for

high precision measurements of - scattering length

& for the first time - various asymmetries


51

Large statistics of K± decays is accumulated for the study

of various rare decays

Precise measurement of K± leptonics & semileptonics decays

contributes to the CKM unitarity & -e universality

checks

NA48/2NA48/2(cont.)


52

2003 data-analysis ongoing

2004 data-calibrated, reprocessed & filtered-analysis has started

NA48/2NA48/2(cont.)


53

Resources Request for 2006

• Data storage at CERN:

reserve CASTOR space

~ 5 TB for MC data

~ 30 TB for possible reprocessing (?),

• CPU power:

guaranteed share for ongoing analysis


54

Spares


55

Results on Ag

Other experiment data on Agc

BNL (1970): (- 7.0 ± 5.3)∙10-3

FNAL, HyperCP –2000 (preliminary) (2.2±1.5±3.7)∙10-3

Serpukhov data on Ag0

I.V.Ajinenko et al., PLB567(2003)159.: (5.1 ± 2.8 )∙10-3

G.A.Akopdzhanov, hep-ex/0406008 prelim.: (0.2 ± 1.9 )∙10-3


56

Leptonic decay selection56 hour minimum-bias run in 2004

K e K

3.91064000

(missing mass)2 ,(GeV/c2)2(missing mass)2 ,(GeV/c2)2


57


58

Matrix element described with 5 Cabibbo-Maksymowicz variables

d5(K+) (s,se) J(m,mecoscose) d(me)d(m)d(cos)d(cosed(

where s m se me

exchange K+ K-→ e+ e-

g’ ei

Ke4 form factors: mK

2 F1 = fsei + cos (fpe

if+ g) à la Pais-Treiman mK

2 F2 = g mK

2 F3 = hei

fit parameters: g, g’, h; with s g; ff gh g

K- vs K+ matrix element: d5(K-, m me e ) = d5(K+, m me e )

line of flight in K rest frame

e plane plane

e

e+

K+

Basic Ke4+ and Ke4

- form factors

Documents

September 27, 2005Status Report, SPSC 1 Experiments NA48/1 & NA48/2 Status Report (SPSC-2005-031) CERN, Cambridge, Chicago, Dubna, Edinburgh, Ferrara,