-
E Abouzaid, M Arenton,
A R Barker,
L Bellantoni,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
M D Corcoran,
B Cox, [......],
J Wang,
H B White,
J Whitmore,
M J Wilking,
R Winston,
E T Worcester,
M Worcester,
T Yamanaka,
E D Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: The KTeV E799 experiment has conducted a search for the rare decays, K(L)→π(0)π(0)μ(+)μ(-) and K(L)→π(0)π(0)X(0)→π(0)π(0)μ(+)μ(-), where the X(0) is a possible new neutral boson that was reported by the HyperCP experiment with a mass of (214.3 ± 0.5) MeV/c(2). We find no evidence for either decay. We obtain upper limits of Br(K(L)→π(0)π(0)X(0)→π(0)π(0)μ(+)μ(-)) < 1.0 × 10(-10) and Br(K(L)→π(0)π(0)μ(+)μ(-)) < 9.2 × 10(-11) at the 90% confidence level. This result rules out the pseudoscalar X(0) as an explanation of the HyperCP result under the scenario that the dsX(0) coupling is completely real.
Physical Review Letters 11/2011; 107(20):201803. · 7.37 Impact Factor
-
KTeV Collaboration,
E Abouzaid, M. Arenton,
A R Barker,
L Bellantoni,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
M D Corcoran, [......],
J Wang,
H B White,
J Whitmore,
M. J. Wilking,
R Winston,
E T Worcester,
M Worcester,
T Yamanaka,
E. D. Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: The KTeV E799 experiment has conducted a search for the rare decays
KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-, where the X0 is a possible new
neutral boson that was reported by the HyperCP experiment with a mass of (214.3
pm 0.5) MeV/c^{2}. We find no evidence for either decay. We obtain upper limits
of Br(KL->pi0pi0X0->pi0pi0mu+mu-) < 1.0 x 10^{-10} and Br(KL->pi0pi0mu+mu-) <
9.2 x 10^{-11} at the 90% confidence level. This result rules out the
pseudoscalar X0 as an explanation of the HyperCP result under the scenario that
the \bar{d}sX0 coupling is completely real.
05/2011;
-
E. Abouzaid, M. Arenton,
A. R. Barker,
M. Barrio,
L. Bellantoni,
E. Blucher,
G. J. Bock,
C. Bown,
E. Cheu,
R. Coleman, [......],
J. Wang,
H. B. White,
J. Whitmore,
M. J. Wilking,
B. Winstein,
R. Winston,
E. T. Worcester,
T. Yamanaka,
E. D. Zimmerman,
R. F. Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: We present precise tests of CP and CPT symmetry based on the full data set of K→ππ decays collected by the KTeV experiment at Fermi National Accelerator Laboratory during 1996, 1997, and 1999. This data set contains 16×106 K→π0π0 and 69×106 K→π+π- decays. We measure the direct CP violation parameter Re(ϵ′/ϵ)=(19.2±2.1)×10-4. We find the KL-KS mass difference Δm=(5270±12)×106ℏ s-1 and the KS lifetime τS=(89.62±0.05)×10-12 s. We also measure several parameters that test CPT invariance. We find the difference between the phase of the indirect CP violation parameter ϵ and the superweak phase: ϕϵ-ϕSW=(0.40±0.56)°. We measure the difference of the relative phases between the CP violating and CP conserving decay amplitudes for K→π+π- (ϕ+-) and for K→π0π0 (ϕ00): Δϕ=(0.30±0.35)°. From these phase measurements, we place a limit on the mass difference between K0 and K̅ 0: ΔM<4.8×10-19 GeV/c2 at 95% C.L. These results are consistent with those of other experiments, our own earlier measurements, and CPT symmetry.
Phys. Rev. D. 05/2011; 83(9).
-
KTeV Collaboration,
E Abouzaid, M. Arenton,
A R Barker,
M Barrio,
L Bellantoni,
E Blucher,
G J Bock,
C Bown,
E Cheu, [......],
J Wang,
H B White,
J Whitmore,
M. J. Wilking,
B Winstein,
R Winston,
E T Worcester,
T Yamanaka,
E. D. Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: We present precise tests of CP and CPT symmetry based on the full dataset of
K to pipi decays collected by the KTeV experiment at Fermi National Accelerator
Laboratory during 1996, 1997, and 1999. This dataset contains 16 million K to
2pi0 and 69 million K to pi+pi- decays. We measure the direct CP violation
parameter Re(epsilon'/epsilon) = (19.2 pm 2.1)x10-4. We find the KL-KS mass
difference Deltam = (5270 pm 12)x10^6 hbar/s and the KS lifetime tauS = (89.62
pm 0.05)x10-12 s. We also measure several parameters that test CPT invariance.
We find the difference between the phase of the indirect CP violation
parameter, epsilon, and the superweak phase, phi_epsilon - phi_SW = (0.40 pm
0.56) degrees. We measure the difference of the relative phases between the CP
violating and CP conserving decay amplitudes for K to pi+pi- (phi+-) and for K
to 2pi0 (phi00), Delta phi = (0.30 pm 0.35) degrees. From these phase
measurements, we place a limit on the mass difference between K0 and K0bar,
DeltaM < 4.8 x 10-19 GeV/c^2 at 95% C.L. These results are consistent with
those of other experiments, our own earlier measurements, and CPT symmetry.
10/2010;
-
E. Abouzaid, M. Arenton,
A. R. Barker,
L. Bellantoni,
E. Blucher,
G. J. Bock,
E. Cheu,
R. Coleman,
M. D. Corcoran,
B. Cox, [......],
M. J. Wilking,
R. Winston,
E. T. Worcester,
T. Yamanaka,
E. D. Zimmerman,
R. F. Zukanovich,
Véronique Bernard,
Micaela Oertel,
Emilie Passemar,
Jan Stern
[show abstract]
[hide abstract]
ABSTRACT: Using the published KTeV samples of KL→π±e∓ν and KL→π±μ∓ν decays, we perform a reanalysis of the scalar and vector form factors based on the dispersive parametrization. We obtain phase-space integrals IKe=0.154 46±0.000 25 and IKμ=0.102 19±0.000 25. For the scalar form factor parametrization, the only free parameter is the normalized form factor value at the Callan-Treiman point (C); our best-fit results in lnC=0.1915±0.0122. We also study the sensitivity of C to different parametrizations of the vector form factor. The results for the phase-space integrals and C are then used to make tests of the standard model. Finally, we compare our results with lattice QCD calculations of FK/Fπ and f+(0).
Phys. Rev. D. 03/2010; 81(5).
-
E. Abouzaid, M. Arenton,
A. R. Barker,
L. Bellantoni,
E. Blucher,
G. J. Bock,
E. Cheu,
R. Coleman,
M. D. Corcoran,
G. Corti, [......],
J. Wang,
H. B. White,
J. Whitmore,
M. Wilking,
R. Winston,
E. T. Worcester,
M. Worcester,
T. Yamanaka,
E. D. Zimmerman,
R. F. Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: The KTeV E799 experiment has conducted a search for the rare decay KL→π0π0γ via the topology KL→π0πD0γ (where πD0→γe+e-). Because of Bose statistics of the π0 pair and the real nature of the photon, the KL→π0π0γ decay is restricted to proceed at lowest order by the CP conserving direct emission (DE) of an E2 electric quadrupole photon. The rate of this decay is interesting theoretically since chiral perturbation theory predicts that this process vanishes at level O(p4). Therefore, this mode probes chiral perturbation theory at O(p6). In this paper we report a determination of an upper limit of 2.43×10-7 (90% CL) for KL→π0π0γ. This is approximately a factor of 20 lower than previous results.
Phys. Rev. D. 08/2008; 78(3).
-
E. Abouzaid, M. Arenton,
A. R. Barker,
L. Bellantoni,
E. Blucher,
G. J. Bock,
E. Cheu,
R. Coleman,
M. D. Corcoran,
B. Cox, [......],
J. Wang,
H. B. White,
J. Whitmore,
M. J. Wilking,
B. Winstein,
R. Winston,
E. T. Worcester,
T. Yamanaka,
E. D. Zimmerman,
R. F. Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: Using a sample of 68.3×106 KL→π0π0π0 decays collected in 1996–1999 by the KTeV (E832) experiment at Fermilab, we present a detailed study of the KL→π0π0π0 Dalitz plot density. We report the first observation of interference from KL→π+π-π0 decays in which π+π- rescatters to π0π0 in a final-state interaction. This rescattering effect is described by the Cabibbo-Isidori model, and it depends on the difference in pion scattering lengths between the isospin I=0 and I=2 states, a0-a2. Using the Cabibbo-Isidori model, and fixing (a0-a2)mπ+=0.268±0.017 as measured by the CERN-NA48 collaboration, we present the first measurement of the KL→π0π0π0 quadratic slope parameter that accounts for the rescattering effect: h000=(+0.59±0.20stat±0.48syst±1.06ext)×10-3, where the uncertainties are from data statistics, KTeV systematic errors, and external systematic errors. Fitting for both h000 and a0-a2, we find h000=(-2.09±0.62stat±0.72syst±0.28ext)×10-3, and mπ+(a0-a2)=0.215±0.014stat±0.025syst±0.006ext; our value for a0-a2 is consistent with that from NA48.
Phys. Rev. D. 08/2008; 78(3).
-
E. Abouzaid, M. Arenton,
A. R. Barker,
L. Bellantoni,
E. Blucher,
G. J. Bock,
E. Cheu,
R. Coleman,
M. D. Corcoran,
B. Cox, [......],
J. Wang,
H. B. White,
J. Whitmore,
M. J. Wilking,
B. Winstein,
R. Winston,
E. T. Worcester,
T. Yamanaka,
E. D. Zimmerman,
R. F. Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: We report on a new measurement of the branching ratio B(KL→π0γγ) using the KTeV detector. We reconstruct 1982 events with an estimated background of 608, that results in B(KL→π0γγ)=(1.29±0.03stat±0.05syst)×10-6. We also measure the parameter, aV, which characterizes the strength of vector meson exchange terms in this decay. We find aV=-0.31±0.05stat±0.07syst. These results utilize the full KTeV data set collected from 1997 to 2000 and supersede earlier KTeV measurements of the branching ratio and aV.
Phys. Rev. D. 06/2008; 77(11).
-
E Abouzaid, M Arenton,
A R Barker,
L Bellantoni,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
M D Corcoran,
B Cox, [......],
J Wang,
H B White,
J Whitmore,
M J Wilking,
B Winstein,
R Winston,
E T Worcester,
T Yamanaka,
E D Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: We present a new determination of the parity of the neutral pion via the double Dalitz decay pi0-->e+e-e+e-. Our sample, which consists of 30,511 candidate decays, was collected from KL-->pi0pi0pi0 decays in flight at the KTeV-E799 experiment at Fermi National Accelerator Laboratory. We confirm the negative pi0 parity and place a limit on scalar contributions to the pi0-->e+e-e+e- decay amplitude of less than 3.3% assuming CPT conservation. The pi0gamma*gamma* form factor is well described by a momentum-dependent model with a slope parameter fit to the final state phase-space distribution. Additionally, we have measured the branching ratio of this mode to be B(pi0-->e+e-e+e-)=(3.26+/-0.18)x10(-5).
Physical Review Letters 05/2008; 100(18):182001. · 7.37 Impact Factor
-
KTeV Collaboration,
E Abouzaid, M. Arenton,
A R Barker,
L Bellantoni,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
M D Corcoran, [......],
J Wang,
H B White,
J Whitmore,
M. J. Wilking,
B Winstein,
R Winston,
E T Worcester,
T Yamanaka,
E. D. Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: We report on a new measurement of the branching ratio B(KL->pi0 gamma gamma)using the KTeV detector. We reconstruct 1982 events with an estimated background of 608, that results in B(KL -> pi0 gamma gamma) = (1.29 +/- 0.03(stat) +/- 0.05(syst)) x 10**-6. We also measure the parameter, aV, which characterizes the strength of vector meson exchange terms in this decay. We find aV = -0.31 +/- 0.05(stat) +/- 0.07(syst). These results utilize the full KTeV data set collected from 1997 to 2000 and supersede earlier KTeV measurements of the branching ratio and aV. Comment: 8 pages, 8 figures
04/2008;
-
E Abouzaid, M Arenton,
A R Barker,
L Bellantoni,
A Bellavance,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
M D Corcoran, [......],
J Whitmore,
M J Wilking,
B Winstein,
R Winston,
C Wolfe,
E T Worcester,
M Worcester,
T Yamanaka,
E D Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: The Fermilab KTeV experiment has searched for lepton-flavor-violating decays of the K(L) meson in three decay modes. We observe no events in the signal region for any of the modes studied, and we set the following upper limits for their branching ratios at the 90% C.L.: BR(K(L) --> pi(0) micro(+/-) e(-/+)) <7.6 x 10(-11); BR(K(L) --> pi(0)pi(0) micro(+/-) e(-/+)) <1.7 x 10(-10); BR(pi(0) --> micro(+/-) e(-/+)) <3.6 x 10(-10). This result represents a factor of 82 improvement in the branching ratio limit for K(L) --> pi(0) micro(+/-) e(-/+) and is the first reported limit for K(L) --> pi(0)pi(0) micro(+/-) e(-/+).
Physical Review Letters 04/2008; 100(13):131803. · 7.37 Impact Factor
-
E Abouzaid, M. Arenton,
A R Barker,
L Bellantoni,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
M D Corcoran,
B Cox, [......],
J Wang,
H B White,
J Whitmore,
M. J. Wilking,
B Winstein,
R Winston,
E T Worcester,
T Yamanaka,
E. D. Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: We present a new determination of the parity of the neutral pion via the double Dalitz decay pi^0 -> e+ e- e+ e-. Our sample, which consists of 30511 candidate decays, was collected from K_L -> pi0 pi0 pi0 decays in flight at the KTeV-E799 experiment at Fermi National Accelerator Laboratory. We confirm the negative pi^0 parity, and place a limit on scalar contributions to the pi^0 -> e+ e- e+ e- decay amplitude of less than 3.3% assuming CPT conservation. The pi^0 gamma* gamma* form factor is well described by a momentum-dependent model with a slope parameter fit to the final state phase space distribution. Additionally, we have measured the branching ratio of this mode to be B(pi^0 -> e+ e- e+ e-) = (3.26 +- 0.18) x 10^(-5).
03/2008;
-
KTeV Collaboration: E. Abouzaid, M. Arenton,
A R Barker,
L Bellantoni,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
M D Corcoran,
G Corti, [......],
J Wang,
H B White,
J Whitmore,
M Wilking,
R Winston,
E T Worcester,
M Worcester,
T Yamanaka,
E. D. Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: The KTeV E799 experiment has conducted a search for the rare decay $K_{L}\to\pi^{0}\pi^{0}\gamma$ via the topology $K_{L}\to\pi^{0}\pi^{0}_D\gamma$ (where $\pi^0_D\to\gamma e^+e^-$). Due to Bose statistics of the $\pi^0$ pair and the real nature of the photon, the $K_{L}\to\pi^{0}\pi^{0}\gamma$ decay is restricted to proceed at lowest order by the CP conserving direct emission (DE) of an E2 electric quadrupole photon. The rate of this decay is interesting theoretically since chiral perturbation theory predicts that this process vanishes at level $O(p^4)$. Therefore, this mode probes chiral perturbation theory at $O(p^6)$. In this paper we report a determination of an upper limit of $2.43\times 10^{-7}$ (90% CL) for $K_{L}\to\pi^{0}\pi^{0}\gamma$. This is approximately a factor of 20 lower than previous results.
09/2007;
-
E. Abouzaid, M. Arenton,
A. R. Barker,
L. Bellantoni,
E. Blucher,
G. J. Bock,
E. Cheu,
R. Coleman,
B. Cox,
A. R. Erwin, [......],
J. Wang,
H. B. White,
J. Whitmore,
M. J. Wilking,
R. Winston,
E. T. Worcester,
M. Worcester,
T. Yamanaka,
E. D. Zimmerman,
R. F. Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: We report on a new measurement of the branching ratio B(KL→π0e+e-γ) using the KTeV detector. This analysis uses the full KTeV data set collected from 1997 to 2000. We reconstruct 139 events over a background of 14, which results in B(KL→π0e+e-γ)=(1.62±0.14stat±0.09syst)×10-8. This result supersedes the earlier KTeV measurement of this branching ratio.
Phys. Rev. D. 09/2007; 76(5).
-
E Abouzaid, M Arenton,
A R Barker,
L Bellantoni,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
M D Corcoran,
B Cox, [......],
R Tschirhart,
Y W Wah,
J Wang,
H B White,
J Whitmore,
M J Wilking,
R Winston,
E T Worcester,
T Yamanaka,
E D Zimmerman
[show abstract]
[hide abstract]
ABSTRACT: The E799-II (KTeV) experiment at Fermilab has collected 83 262 K(L)-->e+ e- gamma(gamma) events above a background of 79 events. We measure a decay width, normalized to the K(L)-->pi0pi0pi(D)0 (pi0-->gammagamma, pi0-->gammagamma, pi(D0-->e+ e- gamma(gamma)) decay width, of Gamma(K(L)-->e+e-gamma(gamma))/Gamma(K(L)-->pi0pi0pi(D)0)=(1.3302+/-0.0046(stat)+/-0.0102(syst)) x 10(-3). We also measure parameters of two K(L)gamma*gamma form factor models. In the Bergström-Massó-Singer parametrization, we find Calpha(K*)= -0.517 +/- 0.030(stat) +/- 0.022(syst). We separately fit for the first parameter of the D'Ambrosio-Isidori-Portolés model and find alpha(DIP)= -1.729 +/- 0.043(stat) +/- 0.028(syst).
Physical Review Letters 08/2007; 99(5):051804. · 7.37 Impact Factor
-
E Abouzaid, M Arenton,
A R Barker,
L Bellantoni,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
M D Corcoran,
B Cox, [......],
H B White,
J Whitmore,
M J Wilking,
B Winstein,
R Winston,
E T Worcester,
M Worcester,
T Yamanaka,
E D Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: This Letter is the first report of the K{L}-->pi{+/-}e{-/+}nue{+}e{-} decay. Based on 19 208+/-144 events, we determine the branching fraction, B(K{L}-->pi{+/-}e{-/+}nue{+}e{-}M_{e{+}e{-}}>5 MeV/c{2},E{e{+}e{-}}{*}>30 MeV)=(1.285+/-0.041)x10{-5}, and Gamma(K{e3ee}M{e{+}e{-}}>5 MeV/c{2})/Gamma(K{e3})=[4.57+/-0.04(stat)+/-0.14(syst)]x10{-5}. This ratio agrees with a theoretical prediction based on chiral perturbation theory (ChPT) calculated to O(p{4}). The measured kinematical distributions agree with those predicted by just ChPT O(p{4}), but show significant disagreement with ones predicted by leading-order ChPT.
Physical Review Letters 08/2007; 99(8):081803. · 7.37 Impact Factor
-
KTeV Collaboration: E. Abouzaid, M. Arenton,
A R Barker,
L Bellantoni,
E Blucher,
G J Bock,
E Cheu,
R Coleman,
B Cox,
A R Erwin, [......],
J Wang,
H B White,
J Whitmore,
M. J. Wilking,
R Winston,
E T Worcester,
M Worcester,
T Yamanaka,
E. D. Zimmerman,
R F Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: We report on a new measurement of the branching ratio B(KL -> pi0 e+ e- gamma) using the KTeV detector. This analysis uses the full KTeV data set collected from 1997 to 2000. We reconstruct 139 events over a background of 14, which results in B(KL -> pi0 e+ e- gamma) = (1.62 +/- 0.14 (stat) +/- 0.09 (syst)) x 10^{-8}. This result supersedes the earlier KTeV measurement of this branching ratio.
07/2007;
-
E. Abouzaid, M. Arenton,
A. R. Barker,
L. Bellantoni,
A. Bellavance,
E. Blucher,
G. J. Bock,
E. Cheu,
R. Coleman,
M. D. Corcoran, [......],
H. B. White,
J. Whitmore,
M. J. Wilking,
B. Winstein,
R. Winston,
E. T. Worcester,
M. Worcester,
T. Yamanaka,
E. D. Zimmerman,
R. F. Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: The branching ratio of the rare decay π0→e+e- has been measured precisely, using the complete data set from the KTeV E799-II experiment at Fermilab. We observe 794 candidate π0→e+e- events using KL→3π0 as a source of tagged π0s. The expected background is 52.7±11.2 events, predominantly from high e+e- mass π0→e+e-γ decays. We have measured B(π0→e+e-,(me+e-/mπ0)2>0.95)=(6.44±0.25stat±0.22syst)×10-8, which is above the unitary bound from π0→γγ and within the range of theoretical expectations from the standard model.
Phys. Rev. D. 01/2007; 75(1).
-
E. Abouzaid,
A. Alavi-Harati,
T. Alexopoulos, M. Arenton,
A. R. Barker,
L. Bellantoni,
A. Bellavance,
E. Blucher,
G. J. Bock,
S. Bright, [......],
H. B. White,
J. Whitmore,
M. Wilking,
B. Winstein,
R. Winston,
E. T. Worcester,
M. Worcester,
T. Yamanaka,
E. D. Zimmerman,
R. F. Zukanovich
[show abstract]
[hide abstract]
ABSTRACT: The polarization of Ξ0 and Ξ̅ 0 hyperons produced by 800 GeV/c protons on a BeO target at a fixed targeting angle of 4.8 mrad is measured by the KTeV experiment at Fermilab. Our result of 9.7% for Ξ0 polarization shows no significant energy dependence when compared to a result obtained at 400 GeV/c production energy and at twice our targeting angle. The polarization of the Ξ̅ 0 is measured for the first time and found to be consistent with zero. We also examine the dependence of polarization on production pt.
Phys. Rev. D. 01/2007; 75(1).
-
E. Abouzaid, M. Arenton,
A. R. Barker,
L. Bellantoni,
A. Bellavance,
E. Blucher,
G. J. Bock,
E. Cheu,
R. Coleman,
M. D. Corcoran, [......],
Y. W. Wah,
J. Wang,
H. B. White,
J. Whitmore,
M. Wilking,
B. Winstein,
R. Winston,
E. T. Worcester,
T. Yamanaka,
E. D. Zimmerman
[show abstract]
[hide abstract]
ABSTRACT: Using the published KTeV sample of 2×106 KL→π±e∓ν decays [1] and a new form factor expansion with a rigorous bound on higher order terms [2], we present a new determination of the KL→π±e∓ν form factor and phase space integral. Compared to the previous KTeV result [1], the uncertainty in the new form factor expansion is negligible and results in an overall uncertainty in the phase space integral (IKe) that is a factor of 2 smaller: IKe=0.15392±0.00048.
Phys. Rev. D. 11/2006; 74(9).
