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Author NA62 Collaboration (Cortina Gil, E. et al); Husek, T.
Title Search for heavy neutral lepton production in K+ decays to positrons Type Journal Article
Year 2020 Publication Physics Letters B Abbreviated Journal Phys. Lett. B
Volume 807 Issue Pages 135599 - 9pp
Keywords
Abstract (up) A search for heavy neutral lepton (N) production in K+ -> e(+)N decays using the data sample collected by the NA62 experiment at CERN in 2017-2018 is reported. Upper limits of the extended neutrino mixing matrix element vertical bar U-e4 vertical bar(2) are established at the level of 10(-9) over most of the accessible heavy neutral lepton mass range 144-462 MeV/c(2), with the assumption that the lifetime exceeds 50 ns. These limits improve significantly upon those of previous production and decay searches. The vertical bar U-e4 vertical bar(2) range favoured by Big Bang Nucleosynthesis is excluded up to a mass of about 340 MeV/c(2).
Address [Gil, E. Cortina; Kleimenova, A.; Minucci, E.; Padolski, S.; Petrov, P.; Shaikhiev, A.; Volpe, R.] Catholic Univ Louvain, Louvain La Neuve, Belgium, Email: Evgueni.Goudzovski@cern.ch
Corporate Author Thesis
Publisher Elsevier Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-2693 ISBN Medium
Area Expedition Conference
Notes WOS:000571765700067 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4544
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Author Husek, T.; Leupold, S.
Title Radiative corrections for the decay Sigma(0) -> Lambda e(+)e(-) Type Journal Article
Year 2020 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 80 Issue 3 Pages 218 - 24pp
Keywords
Abstract (up) Electromagnetic form factors serve to explore the intrinsic structure of nucleons and their strangeness partners. With electron scattering at low energies the electromagnetic moments and radii of nucleons can be deduced. The corresponding experiments for hyperons are limited because of the unstable nature of the hyperons. Only for one process this turns to an advantage: the decay of the neutral Sigma hyperon to a Lambda hyperon and a real or virtual photon. Due to limited phase space the effects caused by the Sigma-to-Lambda transition form factors compete with the QED radiative corrections for the decay sigma 0 -> e+e-. These QED corrections are addressed in the present work, evaluated beyond the soft-photon approximation, i.e., over the whole range of the Dalitz plot and with no restrictions on the energy of the radiative photon.
Address [Husek, Tomas] Univ Valencia, IFIC, CSIC, Apt Correus 22085, Valencia 46071, Spain, Email: thusek@ific.uv.es;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6044 ISBN Medium
Area Expedition Conference
Notes WOS:000519253000007 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4329
Permanent link to this record
 
 
Author Husek, T.; Monsalvez-Pozo, K.; Portoles, J.
Title Constraints on leptoquarks from lepton-flavour-violating tau-lepton processes Type Journal Article
Year 2022 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.
Volume 04 Issue 4 Pages 165 - 31pp
Keywords Beyond Standard Model; Effective Field Theories
Abstract (up) Leptoquarks are ubiquitous in several extensions of the Standard Model and seem to be able to accommodate the universality-violation-driven B-meson-decay anomalies and the (g-2)(mu) discrepancy interpreted as deviations from the Standard Model predictions. In addition, the search for lepton-flavour violation in the charged sector is, at present, a major research program that could also be facilitated by the dynamics generated by leptoquarks. In this article, we consider a rather wide framework of both scalar and vector leptoquarks as the generators of lepton-flavour violation in processes involving the tau lepton. We single out its couplings to leptoquarks, thus breaking universality in the lepton sector, and we integrate out leptoquarks at tree level, generating the corresponding dimension-6 operators of the Standard Model Effective Field Theory. In ref. [1] we obtained model-independent bounds on the Wilson coefficients of those operators contributing to lepton-flavour-violating hadron tau decays and l-tau conversion in nuclei, with l = e, mu. Hence, we use those results to translate the bounds into the couplings of leptoquarks to the Standard Model fermions.
Address [Husek, Tomas; Monsalvez-Pozo, Kevin; Portoles, Jorge] Univ Valencia, CSIC, Inst Fis Corpuscular, Apt Correus 2085, E-46071 Valencia, Spain, Email: tomas.husek@thep.lu.se;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1029-8479 ISBN Medium
Area Expedition Conference
Notes WOS:000788594400008 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5210
Permanent link to this record
 
 
Author NA62 collaboration (Cortina Gil, E. et al); Husek, T.
Title Searches for lepton number violating K+ decays Type Journal Article
Year 2019 Publication Physics Letters B Abbreviated Journal Phys. Lett. B
Volume 797 Issue Pages 134794 - 9pp
Keywords
Abstract (up) The NA62 experiment at CERN reports a search for the lepton number violating decays K+ -> pi(-)e(+)e(+) and K+ -> pi(-)mu(+)mu(+) using a data sample collected in 2017. No signals are observed, and upper limits on the branching fractions of these decays of 2.2 x 10(-10) and 4.2 x 10(-11) are obtained, respectively, at 90% confidence level. These upper limits improve on previously reported measurements by factors of 3 and 2, respectively.
Address [Gil, E. Cortina; Kleimenova, A.; Minucci, E.; Padolski, S.; Petrov, R.; Shaikhiev, A.; Volpe, R.; Perrin-Terrin, M.] Catholic Univ Louvain, B-1348 Louvain La Neuve, Belgium, Email: Evgueni.Goudzovski@cern.ch
Corporate Author Thesis
Publisher Elsevier Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-2693 ISBN Medium
Area Expedition Conference
Notes WOS:000488071200017 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4160
Permanent link to this record
 
 
Author NA62 Collaboration (Cortina Gil, E. et al); Husek, T.
Title First search for K+ -> pi(+) nu(nu)over-bar using the decay-in-flight technique Type Journal Article
Year 2019 Publication Physics Letters B Abbreviated Journal Phys. Lett. B
Volume 791 Issue Pages 156-166
Keywords
Abstract (up) The NA62 experiment at the CERN SPS reports the first search for K+ -> pi(+) nu(nu) over bar using the decay-in-flight technique, based on a sample of 1.21 x10(11) K+ decays collected in 2016. The single event sensitivity is 3.15 x10(-10), corresponding to 0.267 Standard Model events. One signal candidate is observed while the expected background is 0.152 events. This leads to an upper limit of 14 x10(-10) on the K+ -> pi(+) nu(nu) over bar branching ratio at 95% CL.
Address [Gil, E. Cortina; Minucci, E.; Padolski, S.; Petrov, P.; Velghe, B.; Volpe, R.; Kleimenova, A.; Perrin-Terrin, M.] Catholic Univ Louvain, B-1348 Louvain La Neuve, Belgium, Email: radoslav.marchevski@cern.ch;
Corporate Author Thesis
Publisher Elsevier Science Bv Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-2693 ISBN Medium
Area Expedition Conference
Notes WOS:000462321800023 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3957
Permanent link to this record