The absolute branching ratio of the K+ -> pi(+) pi(-) pi(+) (gamma) decay, inclusive of final-state radiation, has been measured using similar to 17 million tagged K+ mesons collected with the ...KLOE detector at DA Phi NE, the Frascati phi-factory. The result is: BR(K+ -> pi(+) pi(-) pi(+) (gamma)) = 0.05565 +/- 0.00031(stat) +/- 0.00025(syst) a factor similar or equal to 5 more precise with respect to the previous result. This work completes the program of precision measurements of the dominant kaon branching ratios at KLOE.
We have carried out a new direct search for the CP violating decay K sub(S) arrow right 3 pi super(0)KS arrow right 3 pi 0 with 1.7 fb super(-1) of e super(+)e super(-)e+e- collisions collected by ...the KLOE detector at the Phi -factory DA Phi NE. We have searched for this decay in a sample of about 5.910 super(8)5.9108K sub(S)K sub(L)KSKL events tagging the K sub(S)KS by means of the K sub(L)KL interaction in the calorimeter and requiring six prompt photons. With respect to our previous search, the analysis has been improved by increasing of a factor four the tagged sample and by a more effective background rejection of fake K sub(S)KS tags and spurious clusters. We find no candidates in data and simulated background samples, while we expect 0.12 standard model events. Normalizing to the number of K sub(S) arrow right 2 pi super(0)KS arrow right 2 pi 0 events in the same sample, we set the upper limit on BR(K sub(S) arrow right 3 pi super(0))el2.610 super(-8)BR(KS arrow right 3 pi 0)el2.610-8 at 90% C.L., five times lower than the previous limit. We also set the upper limit on the eta sub(000) eta 000 parameter, | eta sub(000)|el0.0088| eta 000|el0.0088 at 90% C.L., improving by a factor two the latest direct measurement.
We describe the method of measuring the integrated luminosity of the e+e- collider DAΦNE, the Frascati φ-factory. The measurement is done with the KLOE detector selecting large angle Bhabha ...scattering events and normalizing them to the effective cross section. The e+e-→e+e-(γ) cross section is calculated using different event generators which account for the \(\mathcal{O}(\alpha)\) radiative initial and final state corrections, and the φ resonance contribution. The accuracy of the measurement is 0.6%, where 0.3% comes from systematic errors related to the event counting and 0.5% from theoretical evaluations of the cross section.
We have measured the ratio I (e + e - a pi + pi - gamma ) / I (e + e - a mu + mu - gamma ) , with the KLOE detector at DAIBBNE for a total integrated luminosity of similar to 240 pb - 1 . From this ...ratio we obtain the cross section I (e + e - a pi + pi -) . From the cross section we determine the pion form factor | F pi | 2 and the two-pion contribution to the muon anomaly a mu for 0.592 < M pi pi < 0.975 GeV , I pi pi a mu = (385.1 +/- 1.1 stat +/- 2.7 sys + theo) X 10 - 10 . This result confirms the current discrepancy between the Standard Model calculation and the experimental measurement of the muon anomaly.
We have carried out a new direct search for the CP violating decay KS→3π0 with 1.7 fb−1 of e+e− collisions collected by the KLOE detector at the Φ-factory DAΦNE. We have searched for this decay in a ...sample of about 5.9×108KSKL events tagging the KS by means of the KL interaction in the calorimeter and requiring six prompt photons. With respect to our previous search, the analysis has been improved by increasing of a factor four the tagged sample and by a more effective background rejection of fake KS tags and spurious clusters. We find no candidates in data and simulated background samples, while we expect 0.12 standard model events. Normalizing to the number of KS→2π0 events in the same sample, we set the upper limit on BR(KS→3π0)⩽2.6×10−8 at 90% C.L., five times lower than the previous limit. We also set the upper limit on the η000 parameter, |η000|⩽0.0088 at 90% C.L., improving by a factor two the latest direct measurement.
Measurement of with the KLOE detector Babusci, D; Badoni, D; Balwierz-Pytko, I ...
Physics letters. B,
01/2013, Volume:
718, Issue:
3
Journal Article
Peer reviewed
The ratio R IDT = Phi (IDT a pi + pi - gamma ) / Phi (IDT a pi + pi - pi 0) has been measured by analysing 22 million I a IDT gamma decays collected by the KLOE experiment at DAIBBNE, corresponding ...to an integrated luminosity of 558 pb-1. The IDT a pi + pi - gamma proceeds both via the I resonant contribution, and possibly a non-resonant direct term, connected to the box anomaly. Our result, R IDT = 0.1856 +/- 0.0005 stat +/- 0.0028 syst , points out a sizable contribution of the direct term to the total width. The di-pion invariant mass for the IDT a pi + pi - gamma decay could be described in a model-independent approach in terms of a single free parameter, alpha . The determined value of the parameter alpha is alpha = (1.32 +/- 0.08 stat - 0.09 syst + 0.10 +/- 0.02 theo) GeV - 2 .
We have measured the ratio cr (e(+)e(-) -> pi(+)pi(-)gamma)/sigma(e(+)e(-) -> mu(+)mu(-)gamma), with the KLOE detector at DA Phi NE for a total integrated luminosity of similar to 240 pb(-1). ...From this ratio we obtain the cross section sigma (e(+)e(-) -> pi(+)pi(-)gamma). From the cross section we determine the pion form factor vertical bar F-pi vertical bar(2) and the two-pion contribution to the muon anomaly a(mu) for 0.592< M-pi pi < 0.975 GeV, Delta(pi pi) a(mu) = (385.1 +/- 1.1(stat) +/- 2.7(sys+theo)) x 10(-10). This result confirms the current discrepancy between the Standard Model calculation and the experimental measurement of the muon anomaly. (c) 2013 Elsevier B.V. All rights reserved.
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