28 research outputs found
MesonNet 2013 International Workshop. Mini-proceedings
The mini-proceedings of the MesonNet 2013 International Workshop held in
Prague from June 17th to 19th, 2013, are presented. MesonNet is a research
network within EU HadronPhysics3 project (1/2012 -- 12/2014). The web page of
the conference, which contains all talks, can be found at
http://ipnp.mff.cuni.cz/mesonnet13Comment: 106 pages, 53 contributions. Mini-proceedings of the MesonNet 2013
International Workshop. Editors: K. Kampf, A. Kupsc, and P. Masjua
Precision measurement of and determination of the contribution to the muon anomaly with the KLOE detector
We have measured the ratio
, with the KLOE detector at DANE for a total integrated
luminosity of 240 pb. From this ratio we obtain the cross section
. From the cross section we determine the
pion form factor and the two-pion contribution to the muon anomaly
for GeV, = . This result confirms the
current discrepancy between the Standard Model calculation and the experimental
measurement of the muon anomaly.Comment: 18 pages, 8 figures, minor text corrections, one table added, version
to appear on Physics Letters
Measurement of {\eta} meson production in {\gamma}{\gamma} interactions and {\Gamma}({\eta}-->{\gamma}{\gamma}) with the KLOE detector
We present a measurement of {\eta} meson production in photon-photon
interactions produced by electron-positron beams colliding with \sqrt{s}=1 GeV.
The measurement is done with the KLOE detector at the \phi-factory DA{\Phi}NE
with an integrated luminosity of 0.24 fb^{-1}. The e^+e^- --> e^+e^-{\eta}
cross section is measured without detecting the outgoing electron and positron,
selecting the decays {\eta}-->{\pi}^+{\pi}^-{\pi}^0 and
{\eta}-->{\pi}^0{\pi}^0{\pi}^0. The most relevant background is due to e^+e^-
--> {\eta}{\gamma} when the monochromatic photon escapes detection. The cross
section for this process is measured as {\sigma}(e^+e^- -->{\eta}{\gamma}) =
(856 \pm 8_{stat} \pm 16_{syst}) pb. The combined result for the e^+e^-
-->e^+e^-{\eta} cross section is {\sigma}(e^+e^- -->e^+e^-{\eta}) = (32.72 \pm
1.27_{stat} \pm 0.70_{syst}) pb. From this we derive the partial width
{\Gamma}({\eta}-->{\gamma}{\gamma}) = (520 \pm 20_{stat} \pm 13_{syst}) eV.
This is in agreement with the world average and is the most precise measurement
to date.Comment: Version accepted by JHE
A new limit on the CP violating decay KS -> 3pi0 with the KLOE experiment
We have carried out a new direct search for the CP violating decay KS -> 3pi0
with 1.7 fb^-1 of e+e- collisions collected by the KLOE detector at the
phi-factory DAFNE. We have searched for this decay in a sample of about 5.9 x
10^8 KS KL 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 -> 2pi0 events in the same sample, we set the upper limit on BR(KS ->
3pi0 < 2.6 x 10^-8 at 90% C.L., five times lower than the previous limit. We
also set the upper limit on the eta_000 parameter, |eta_000 | < 0.0088 at 90%
C.L., improving by a factor two the latest direct measurement.Comment: Accepted for publication in Physics Letters B (15 pages, 13 figures
Measurement of \Gamma(\eta -> \pi^+\pi^-\gamma)/\Gamma(\eta -> \pi^+\pi^-\pi^0) with the KLOE Detector
The ratio R_{\eta}=\Gamma(\eta -> \pi^+\pi^-\gamma)/\Gamma(\eta ->
\pi^+\pi^-\pi^0) has been measured by analyzing 22 million \phi \to \eta \gamma
decays collected by the KLOE experiment at DA\PhiNE, corresponding to an
integrated luminosity of 558 pb^{-1}. The \eta \to \pi^+\pi^-\gamma proceeds
both via the \rho resonant contribution, and possibly a non-resonant direct
term, connected to the box anomaly. Our result, R_{\eta}= 0.1856\pm
0.0005_{stat} \pm 0.0028_{syst}, points out a sizable contribution of the
direct term to the total width. The di-pion invariant mass for the \eta ->
\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 \pm 0.08_{stat} +0.10/-0.09_{syst}\pm 0.02_{theo})
GeV^{-2}Comment: Paper in press, accepted by PL
Study of the Dalitz decay ϕ→ηe+e- with the KLOE detector
We have studied the vector to pseudoscalar conversion decay ϕ→ηe+e-, with η→π0π0π0, with the KLOE detector at DAΦNE. The data set of 1.7 fb-1 of e+e- collisions at s~Mϕ contains a clear conversion decay signal of ~31, 000 events from which we measured a value of BR(ϕ→ηe+e-)=(1.075±0.007±0.038)×10-4. The same sample is used to determine the transition form factor by a fit to the e+e- invariant mass spectrum, obtaining bϕη=(1.28±0.10-0.08+0.09) GeV-2, that improves by a factor of five the precision of the previous measurement and is in good agreement with VMD expectations
Search for light vector boson production in interactions with the KLOE experiment
We have searched for a light vector boson , the possible carrier of a
"dark force", with the KLOE detector at the DANE \epm\ collider,
motivated by astrophysical evidence for the presence of dark matter in the
universe. Using \epm\ collisions collected with an integrated luminosity of
~pb, we look for a dimuon mass peak in the reaction \epm\to\gam, corresponding to the decay . We find no evidence
for a vector boson signal. We set a 90\% CL upper limit for the mixing
parameter squared between the photon and the boson of 1.610
to 8.610 for the mass region MeV.Comment: 12 pages, 7 figures, version accepted for publication in Physics
Letters
Measurement of the absolute branching ratio of the K+→π+π-π+(γ) decay with the KLOE detector
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. (C) 2014 The Authors. Published by Elsevier B.V
Study of Dalitz decay phi -> eta e+e- with KLOE detector
We have studied the vector to pseudoscalar conversion decay phi -> eta e+e-,
with eta -> pi0pi0pi0, with the KLOE detector at DAPHNE. The data set of 1.7
fb-1 of e+e- collisions at sqrt(s)~Mphi contains a clear conversion decay
signal of ~31,000 events from which we measured a value of BR(phi -> eta
e+e-)=(1.075+-0.007+-0.038)x10-4. The same sample is used to determine the
transition form factor by a fit to the e+e- invariant mass spectrum, obtaining
b(phi eta) =(1.17 +- 0.10 + 0.07) GeV-2, that improves by a factor of five the
precision of the previous measurement and is in good agreement with VMD
expectations.Comment: 13 pages, 6 figures, submitted to PL
Test of CPT and Lorentz symmetry in entangled neutral kaons with the KLOE experiment
Neutral kaon pairs produced in phi decays in anti-symmetric entangled state can be exploited to search for violation of CPT symmetry and Lorentz invariance. We present an analysis of the CP-violating process phi -> KSKL -> pi(+)pi(-)pi(+)pi(-) based on 1.7 fb(-1) of data collected by the KLOE experiment at the Frascati phi-factory DA Phi NE. The data are used to perform a Measurement of the CPT-violating parameters Delta a(mu) for neutral kaons in the context of the Standard Model Extension framework. The parameters measured in the reference frame of the fixed stars are:Delta a(0) = (-6.0 +/- 7.7(stat)+/- 3.1(syst)) X 10(-18) GeV,Delta a(x) = (0.9 +/- 1.5(stat)+/- 0.6(syst)) X 10(-18) GeV,Delta a(y) = (-2.0 +/- 1.5(stat)+/- 0.5(syst)) X 10(-18) GeV,Delta a(z) = (3.1 +/- 1.7(stat)+/- 0.5(syst)) X 10(-18) GeV.These are presently the most precise measurements in the quark sector of the Standard Model Extension. (C) 2014 The Authors. Published by Elsevier B.V