Publications by Alina Kleimenova

Related publications (10)

A study of the K^(+) → π^(0)e^(+)νγ decay

Alessandro Mapelli, Alina Kleimenova, Radoslav Marchevski

A sample of 1.3 x 10^(5) K^(+) → π^(0)e^(+)νγ candidates with less than 1% background was collected by the NA62 experiment at the CERN SPS in 2017-2018. Branching fraction measurements are obtained at percent relative precision in three restricted kinemati ...

Springer Nature2023

Search for Leptonic Decays of Dark Photons at NA62

Radoslav Marchevski, Alina Kleimenova

The NA62 experiment at CERN, configured in beam-dump mode, has searched for dark photon decays in flight to electron-positron pairs using a sample of 1.4 x 10(17) protons on dump collected in 2021. No evidence for a dark photon signal is observed. The comb ...

American Physical Society (APS)2024

Search for dark photon decays to μ+μ- at NA62

Alina Kleimenova, Radoslav Marchevski

The NA62 experiment at CERN, designed to study the ultra-rare decay K+ -> pi(+) nu(nu) over bar, has also collected data in beam-dump mode. In this configuration, dark photons may be produced by protons dumped on an absorber and reach a decay volume beginn ...

Springer Nature2023

Search for Hadronic Decays of Feebly-interacting Particles at Na62

Radoslav Marchevski, Alina Kleimenova, Xiafei Chang

The NA62 experiment at CERN has the capability to collect data in a beam-dump mode, where 400 GeV protons are dumped on an absorber. In this configuration, New Physics particles, including dark photons, dark scalars, and axion-like particles, may be produc ...

SPRINGER2025

Improved calorimetric particle identification in NA62 using machine learning techniques

Alessandro Mapelli, Radoslav Marchevski, Alina Kleimenova

Measurement of the ultra-rare K+ -> pi(+)nu(nu) over bar over bar decay at the NA62 experiment at CERN requires high-performance particle identification to distinguish muons from pions. Calorimetric identification currently in use, based on a boosted decis ...

Springer Nature2023

Search for K+ decays into the π+e+e-e+e- final state

Alessandro Mapelli, Radoslav Marchevski, Alina Kleimenova

The first search for ultra-rare K+ decays into the pi(+)e(+)e(-) e(+) e(-) final state is reported, using a dataset collected by the NA62 experiment at CERN in 2017-2018. An upper limit of 1.4x10(-8) at 90% CL is obtained for the branching ratio of the K+ ...

Elsevier2023

Observation of the K+→π+νν¯ decay and measurement of its branching ratio

Radoslav Marchevski, Alina Kleimenova, Xiafei Chang

A measurement of the K+→π+νν¯ decay by the NA62 experiment at the CERN SPS is presented, using data collected in 2021 and 2022. This dataset was recorded, after modifications to the beamline and detectors, at a higher instantaneous beam intensity with resp ...

Springer2025

First search for K+ → π0πμe decays

Radoslav Marchevski, Alina Kleimenova, Xiafei Chang

The first search for the lepton number violating decay K+→π0π−μ+e+ and lepton flavour violating decays K+→π0π+μ−e+, K+→π0π+μ+e− has been performed using a dataset collected by the NA62 experiment at CERN in 2016–2018. Upper limits of 2.9×10−10, 3.1×10−10 a ...

2024

First detection of a tagged neutrino in the NA62 experiment

Radoslav Marchevski, Alina Kleimenova, Xiafei Chang

The NA62 experiment at the CERN SPS reports the first detection of a tagged neutrino candidate based on the data collected in 2022. The candidate consists of a K+→μ+νμ decay where the charged particles are reconstructed and the neutrino is detected through ...

2025

Measurement of the K+ → π+γγ decay

Alessandro Mapelli, Radoslav Marchevski, Alina Kleimenova

A sample of 3984 candidates of the K+ -> pi(+)gamma gamma decay, with an estimated background of 291 +/- 14 events, was collected by the NA62 experiment at CERN during 2017-2018. In order to describe the observed di-photon mass spectrum, the next-to-leadin ...

Elsevier2024