kaon physics
DESCRIPTION
Kaon Physics. New determination of |V us | Using very rare K decays to search for new physics Future efforts Summary. R. Ray Fermilab. July 6 - 9, 2005. Kaon Experiments with New Results at KAON 2005. CERN NA48: 1997-2001 K L NA48/1: 2000, 02 K s NA48/2: 2003, 04 K . Fermilab, - PowerPoint PPT PresentationTRANSCRIPT
-
Kaon PhysicsR. RayFermilabJuly 6 - 9, 2005New determination of |Vus|
Using very rare K decays to search for new physics
Future efforts
Summary
Physics in Collision 2005 R. Ray - Fermilab
-
Physics in Collision 2005 R. Ray - Fermilab
-
Resolution of the CKM Unitarity ProblemUnitarity Problem1 -(|Vud|2 + |Vus|2 + |Vub|2) = 0.0043 0.0019 (PDG 2002)
2s difference from unitarityFirst Row
Physics in Collision 2005 R. Ray - Fermilab
-
2002 PDG |Vux| Evaluations|Vud| = 0.9734 0.0008 from 0+ 0+ nuclear b decays, neutron decay.
|Vus| = 0.2196 0.0023 from K+, K0 decays to pen (pmn not used by PDG because of large form factor uncertainties)
|Vub| = (3.6 0.7) 10-3 from semileptonic B decays2003 K+ measurement from BNL E865 consistent with unitarity
Interesting to revisit KL measurements (PDG fit values based on averagesof many old experiments with large errors)
Physics in Collision 2005 R. Ray - Fermilab
-
Determination of Vus by Measurement of Kl3 DecaysMeasurement of ratesB(K pen), B(K pmn)Measurement of form factors neededto calculate phase space integralsRadiative corrections(theory)Form factors at t=0 (theory)WANT THISGKl3 = B(Kl3)/tL(tL from PDG)Only external measurement(New measurement from KLOE now available!)
Physics in Collision 2005 R. Ray - Fermilab
-
2003: BNL E865 Measurement of B(K+ p0e+n) Using 70,000 K+e3 decays normalized to K+ p+p-, K+ p0m+n, K+ p+p0p0, they found B(K+e3) to be 5% higher than PDG.
Result is consistent with CKM unitarity at 1% level.
Assumes other K+ branching ratios are correct.Data/MC comparison fore+ momentum from p0 e+e-g decay for signal and normalization modes.
Physics in Collision 2005 R. Ray - Fermilab
-
New Measurements in 2004
the kaon revolution - MarcianoKTeV measured 6 largest branching fractions and KL semileptonic form factors (Ke3 and Km3) + Ke3g and Km3g
NA48 measured KL pen/charged fraction, Ke3 FF and B(KL p0p0p0), Ke3g and Km3g
KLOE measured 4 main KL branching fractions, KL lifetime, B(KS pen). Also a new measurement of B(K+ m+n) and first observation of B(KS pmn).
New K+e3 measurement from NA48
New K+e3 branching fraction and FF results from ISTRA+.
Physics in Collision 2005 R. Ray - Fermilab
-
KTeV measures the following 5 ratios of partial decay rates:
These six decay modes account for 99.93% of KL decays, so ratios may be combined to determine branching fractions.
NA48 measures:
G(KL p e n) / G(2 track) and B(KL p0p0p0), Ke3 FF, B(Ke3)
KL measurements consistent with KTeV, K result consistent with E865
KLOE (e+e- K+K-, KLKS) can tag one kaon and measure branching fractions using accompanying kaon. They measure branching fractions for the 4 main KL decay modes.
KL Branching Ratio MeasurementsE.g.
Physics in Collision 2005 R. Ray - Fermilab
-
Simple event reconstruction and selection may be used to distinguish different decay modes with very little background
Physics in Collision 2005 R. Ray - Fermilab
-
KTeV Measured Partial Width RatiosData - MC Comparison for Radiative Photon Candidates
It is critical to model radiation properly in MCRadiation changes Ke3 acceptance by 3%. Effect on other modes is < 0.5%
Both KTeV and NA48 have published new measurementsof B(Ke3g) and B(Km3g)
ModePartial Width RatioGKm3 / GKe30.6640 0.0014 0.0022G000 / GKe30.4782 0.0014 0.0053G+-0 / GKe30.3078 0.0005 0.0017G+- / GKe3(4.856 0.017 0.023)10-3G00 / G000(4.446 0.016 0.019) 10-3
Physics in Collision 2005 R. Ray - Fermilab
-
Comparison of KTeV, NA48, KLOE and PDG KL Branching FractionsValue based on PDG-style fit to all new measurements (KTeV, KLOE, NA48)
Physics in Collision 2005 R. Ray - Fermilab
-
KLOE KL Lifetime MeasurementsIndirect method - From BR measurements
Detector acceptance depends on tL. SB(KL major decays)[tL] + 0.0036 1 tL
tL = (50.72 0.14 0.33) ns
Direct Method using KL p0p0p0 - Fit proper time distribution.
tL = (50.87 0.16 0.26) nsCombining both KLOE results:
tL = (50.81 0.23) ns Old PDG Average: tL = (50.98 0.4) ns
New measurement of t soon! Sum of rare decays
Physics in Collision 2005 R. Ray - Fermilab
-
Semileptonic Form Factor Measurements
(to determine IK integrals).
Phase space, no form factorPhase space with form factorIK depends on the two independent semileptonic FFs.t/mp2t/mp2Ke3 Km3
y y
- y
Physics in Collision 2005 R. Ray - Fermilab
-
KL Form Factor ResultsLinear ModelKm3 Form Factor
Physics in Collision 2005 R. Ray - Fermilab
-
Charged Kaon DecaysNew measurement of semileptonic form factors from ISTRA+
New measurements of B(K p0en):
BUT, decay modes used as normalization for K p0en have not been re-measured. (KLOE, NA48)
Also, new measurement of K+ lifetime is needed (KLOE)
Physics in Collision 2005 R. Ray - Fermilab
-
Input to Recent |Vus| Calculation
B(KLe3): KTeV, KLOE, NA48B(KLm3): KTeV, KLOEB(KSe3): KLOEB(K+e3): E865, NA48, ISTRA+tL: KLOE + PDG averagetS: KTeV, NA48 averaget+: PDGShort-distance radiative correction = 1.023 (Sirlin)
Long-distance radiative corrections: (Andre, Cirigliano et al.) de = 0.0104 0.002 dm = 0.019 0.003 de+ = 0.0006 0.002
f+(0) = 0.961 0.008 (Leutwyler - Roos)
Physics in Collision 2005 R. Ray - Fermilab
-
Comparison with Unitarity|Vus| = 0.2261 0.00211 -(|Vud|2 + |Vus|2 + |Vub|2) = 0.0004 0.0011 Unitarity restored!Average of all recent resultsaccounting for correlations|Vus|f+(0) = 0.2173 0.0008 Uses updated |Vud| = 0.9739 0.0003(Hardy, Towner; Marciano, Sirlin - KAON 2005)Using f+(0) = 0.961 0.008 (Leutwyler - Roos):
Physics in Collision 2005 R. Ray - Fermilab
-
Consistency of BR and FF results withLepton Universality Compare for Ke3 and Km3 1.0058(10)from T. Andre0.6622(18)from KTeVSame test with PDG values gives 1.0270 0.0182
Physics in Collision 2005 R. Ray - Fermilab
-
Very Rare Kaon Decays
Physics in Collision 2005 R. Ray - Fermilab
-
The theoretically cleanest processes in meson decays
Suppressed to the 1-loop level by GIM, no tree level pollution.
No competing long-distance contributions.
No significant QCD corrections
Hadronic m.e. from K pen
Physics in Collision 2005 R. Ray - Fermilab
-
B(K+ p+nn)[SM] = C+ |Vcb|4 [(r - rc)2 + (sh)2] = (8.0 1.0) x 10-11
__~ 5% error due to charmError on measured parametersTheoretical error ~ 1%!Controls amountof CPV in SM__
_
K+ p+nnKL p0nnCP ConservingCP ViolatingCKMVtdIm(VtsVtd) ~ hContributionstop and charmonly topBR scale dep. 20% (LO) 5% (NLO)10% (LO)1% (NLO)BR (SM)(8.0 1.0)x10-11(3.0 0.6)x10-11BR (Exp.)(1.47 )x10-10 (BNL 787)< 5.9x10-7 (KTeV)
Physics in Collision 2005 R. Ray - Fermilab
-
Testing the Standard ModelIn K pnn the phase b arises from Z0 diagrams (DS=1) while in A(J/y KS) it originates in the Bd - Bd box diagram (DB=2)
Any non-minimal contribution to Z0 diagrams could lead to a violation of:
Any deviation from this relation is a definitive sign of new physics
This is one of the cleanest tests of the SM
Complementary to searches at the energy frontier
When new physics appears at the TeVatron/LHC, rare decays will help to understand the details
__
Physics in Collision 2005 R. Ray - Fermilab
-
Some Predictions from Beyond the Standard ModelComplied by S. Kettell__
B(K+ pnn) x 10-11B(KL p0nn) x 10-11SM8.0 1.03.0 0.6Minimal Flavor Violationhep-ph/031020819.19.9Enhanced EW PenguinsNP B697 1337.5 2.131 10Extra down type singlet quark modelhep-ph/04081421510MSSMhep-ph/04081424050
Physics in Collision 2005 R. Ray - Fermilab
-
E391a at KEKExperimental method
(1) Measure g hit position and energy(2) Reconstruct Z decay vertex assuming M(2g) = M(p0)(3) Require missing Pt and decay vertex in fiducial volume
Physics in Collision 2005 R. Ray - Fermilab
-
Pencil Beam
~ 4 cm x 4 cm at CsI
improves transverse momentum resolution
Hermetic photon veto
reject background from KL 2p0 where two photons are missing
Vacuum
10-5 pa in decay region
minimize background from neutron interactions
detectors in low vacuum region (~0.1 Pa) separated from high vacuum region by thin membrane
In Run I, part of vacuum membrane drooped into beam resulting in neutron backgrounds. Fixed for Run II.
E391a (cont.)
Physics in Collision 2005 R. Ray - Fermilab
-
KEK E391a (cont.)
Physics in Collision 2005 R. Ray - Fermilab
-
Kaon Decay Background
KL 2p0 background estimated using Monte Carlo simulation
4g invariant mass for both KL 2p0 and 3p0 accurately reproduced
The expected number of events is 0.02 in the signal region and 0.05 in the side band regionKL 2p0 E391a (cont)
Physics in Collision 2005 R. Ray - Fermilab
-
Summary of E391a Background Estimation
Physics in Collision 2005 R. Ray - Fermilab
-
Preliminary E391a Result from 10% of Run I Data SampleMulti p0 backgroundfrom neutron interactionsp0 Pt vs. Reconstructed Z VertexSingle p0 backgroundfrom neutron interactionsZ(cm)Signal BoxNo events in the signal box
S.E.S. = 1.17 x 10-7
BR < 2.86 x 10-7 (90% C.L.)
Based on 1.14 x 109 KL decays
~ 2X better than previous KTeV limit
Run II data in hand
With anticipated Run III data the Grossman-Nir limit may be within reachSevere cuts required to reduce background from membrane. Resulting acceptance 10x lower than design.
Runs II and III will have higher acceptance and lower background.
Physics in Collision 2005 R. Ray - Fermilab
-
Physics in Collision 2005 R. Ray - Fermilab
-
E787 (1995-98) observed two candidates with a background of 0.15 0.05 events
B(K+ p+nn) = (1.57 ) x 10-10+1.75- 0.82_E787/949 (cont.)Results from region 1E949 is a modest upgrade to E787 to accommodate higher rates
SES goal of < 10-11 5-10 SM events
Only 20% of running time realized
E949 observed one additional event
SignalBackgroundE78720.14 0.05E94910.30 0.03
Physics in Collision 2005 R. Ray - Fermilab
-
KL p0e+e- and KL p0m+m-
Physics in Collision 2005 R. Ray - Fermilab
-
KTeV: KL p0e+e-BR(KL p0e+e-) 3.50 x 10-10 (90% C.L.) (1999) [PRL 93, 021805 (2004)]BR(KL p0e+e-) 2.8 x 10-10 (90% C.L.) (1997+1999)Blind analysis Box
130 < mgg < 140 MeV/c2485 < meegg < 510 MeV/c2Signal ellipse 2s1 event in signal ellipse
0.99 0.35 expected background events 1999 DataM(eegg)M(gg)
Physics in Collision 2005 R. Ray - Fermilab
-
KTeV: KL p0m+m-2 events in signal region
0.87 0.15 expected background events1997 DataNew result on 1999 data expected soon
Physics in Collision 2005 R. Ray - Fermilab
-
Sensitivity of KL p0ee(mm) to New Physics
Physics in Collision 2005 R. Ray - Fermilab
-
Importance of KS p0e+e- aS is one of two form factorsIndirect CP violating contributionB(KL p0e+e-)IND = B(KS p0e+e-)/ 330Interference termsensitive to Im(lt) = Im(VtdVts*)
Direct CP violating termExtraction of aS from B(KS) along with a measurement of B(KL)allows for extraction of Im(lt) ~ h
Physics in Collision 2005 R. Ray - Fermilab
-
NA48: First Observation of KS p0e+e- 0 events found in control region
7 events found in signal region
Probability of background only ~ 10-10
Physics in Collision 2005 R. Ray - Fermilab
-
NA48: First Observation of KS p0m+m-0 events found in control region
6 events found in signal regionResults for aS are consistent for p0e+e- and p0m+m-
Physics in Collision 2005 R. Ray - Fermilab
-
Future Efforts
Physics in Collision 2005 R. Ray - Fermilab
-
Summary
Physics in Collision 2005 R. Ray - Fermilab
-
Extra Slides
Physics in Collision 2005 R. Ray - Fermilab
-
Summary of KL Lifetime Measurements
Physics in Collision 2005 R. Ray - Fermilab
-
Determination of |h+-| Using B(KL p+p-)KTeV: |h+-| = (2.239 0.005 KTeV 0.008EXT) x 10-3
(using new average tL)
Physics in Collision 2005 R. Ray - Fermilab