Search for π0 decays to invisible particles Cortina Gil, E.; Minucci, E.; Padolski, S. ...
The journal of high energy physics,
02/2021, Letnik:
2021, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A
bstract
The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 10
9
tagged
π
0
mesons from
K
+
→
π
+
π
0
(
γ
), searching for the decay of the
π
0
to invisible particles. No signal ...is observed in excess of the expected background fluctuations. An upper limit of 4
.
4 × 10
−
9
is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay
K
+
→
π
+
X
, where
X
is a particle escaping detection with mass in the range 0.110–0.155 GeV
/c
2
and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming
X
to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.
A drift chamber with a new type of straws for operation in vacuum Azorskiy, N.; Glonti, L.; Gusakov, Yu ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
824
Journal Article
Recenzirano
A 2150×2150mm2 registration area drift chamber capable of working in vacuum is presented. Thin-wall tubes (straws) of a new type are used in the chamber. A large share of these 9.80mm diameter drift ...tubes are made in Dubna from metalized 36µm Mylar film welded along the generatrix using an ultrasonic welding machine created at JINR. The main features of the chamber and some characteristics of the drift tubes are described. Four such chambers with the X, Y, U, V coordinates each, containing 7168 straws in total, are designed and produced at JINR and CERN. They are installed in the vacuum volume of the NA62 setup in order to study the ultra-rare decay K+→π+vv¯ and to search for and study rare meson decays. In autumn 2014 the chambers were used for the first time for the data taking in the experimental run of the NA62 at CERN׳s SPS.
The results of a search for π0 decays to a photon and an invisible massive dark photon at the NA62 experiment at the CERN SPS are reported. From a total of 4.12 × 108 tagged π0 mesons, no signal is ...observed. Assuming a kinetic-mixing interaction, limits are set on the dark photon coupling to the ordinary photon as a function of the dark photon mass, improving on previous searches in the mass range 60–110 MeV/c2. The present results are interpreted in terms of an upper limit of the branching ratio of the electro-weak decay π0→γνν¯\ {\pi}^0\to \gamma \nu \overline{\nu} \, improving the current limit by more than three orders of magnitude.
A search for heavy neutral lepton production in K+ decays using a data sample collected with a minimum bias trigger by the NA62 experiment at CERN in 2015 is reported. Upper limits at the 10−7 to ...10−6 level are established on the elements of the extended neutrino mixing matrix |Ue4|2 and |Uμ4|2 for heavy neutral lepton mass in the ranges 170–448 MeV/c2 and 250–373 MeV/c2, respectively. This improves on the previous limits from HNL production searches over the whole mass range considered for |Ue4|2, and above 300 MeV/c2 for |Uμ4|2.
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