This paper presents a measurement of the electroweak production of two jets in association with a Zγ pair, with the Z boson decaying into two neutrinos. It also presents a search for invisible or partially invisible decays of a Higgs boson with a mass of 125 GeV produced through vector-boson fusion with a photon in the final state. These results use data from LHC proton–proton collisions at s√ = 13 TeV collected with the ATLAS detector and corresponding to an integrated luminosity of 139 fb−1. The event signature, shared by all benchmark processes considered for the measurements and searches, is characterized by a significant amount of unbalanced transverse momentum and a photon in the final state, in addition to a pair of forward jets. Electroweak Zγ production in association with two jets is observed in this final state with a significance of 5.2 (5.1 expected) standard deviations. The measured fiducial cross-section for this process is 1.31±0.29 fb. An observed (expected) upper limit of 0.37 (0.34+0.15−0.10) at 95% confidence level is set on the branching ratio of a 125 GeV Higgs boson to invisible particles, assuming the Standard Model production cross-section. The signature is also interpreted in the context of decays of a Higgs boson into a photon and a dark photon. An observed (expected) 95% CL upper limit on the branching ratio for this decay is set at 0.018 (0.017+0.007−0.005), assuming the Standard Model production cross-section for a 125 GeV Higgs boson.

Observation of electroweak production of two jets in association with an isolated photon and missing transverse momentum, and search for a Higgs boson decaying into invisible particles at 13 $ ext {TeV}$ with the ATLAS detector / G. Aad, B.A.. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - 82:2(2022 Feb 03), pp. 105.1-105.43. [10.1140/epjc/s10052-021-09878-z]

Observation of electroweak production of two jets in association with an isolated photon and missing transverse momentum, and search for a Higgs boson decaying into invisible particles at 13 $ ext {TeV}$ with the ATLAS detector

A. Andreazza
Membro del Collaboration Group
;
E. Ballabene
Membro del Collaboration Group
;
A. Carbone
Membro del Collaboration Group
;
L. Carminati
Membro del Collaboration Group
;
S. D’Auria
Membro del Collaboration Group
;
L. Dell’Asta;M. Fanti
Membro del Collaboration Group
;
M. Lazzaroni
Membro del Collaboration Group
;
C. Meroni
Membro del Collaboration Group
;
D.P. Mungo
Membro del Collaboration Group
;
A. Murrone
Membro del Collaboration Group
;
L. Perini
Membro del Collaboration Group
;
F. Piazza;F. Ragusa
Membro del Collaboration Group
;
A. Stabile
Membro del Collaboration Group
;
2022

Abstract

This paper presents a measurement of the electroweak production of two jets in association with a Zγ pair, with the Z boson decaying into two neutrinos. It also presents a search for invisible or partially invisible decays of a Higgs boson with a mass of 125 GeV produced through vector-boson fusion with a photon in the final state. These results use data from LHC proton–proton collisions at s√ = 13 TeV collected with the ATLAS detector and corresponding to an integrated luminosity of 139 fb−1. The event signature, shared by all benchmark processes considered for the measurements and searches, is characterized by a significant amount of unbalanced transverse momentum and a photon in the final state, in addition to a pair of forward jets. Electroweak Zγ production in association with two jets is observed in this final state with a significance of 5.2 (5.1 expected) standard deviations. The measured fiducial cross-section for this process is 1.31±0.29 fb. An observed (expected) upper limit of 0.37 (0.34+0.15−0.10) at 95% confidence level is set on the branching ratio of a 125 GeV Higgs boson to invisible particles, assuming the Standard Model production cross-section. The signature is also interpreted in the context of decays of a Higgs boson into a photon and a dark photon. An observed (expected) 95% CL upper limit on the branching ratio for this decay is set at 0.018 (0.017+0.007−0.005), assuming the Standard Model production cross-section for a 125 GeV Higgs boson.
Settore FIS/01 - Fisica Sperimentale
Settore ING-INF/07 - Misure Elettriche e Elettroniche
3-feb-2022
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/907712
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