002909518 001__ 2909518
002909518 005__ 20250116012437.0
002909518 0248_ $$aoai:cds.cern.ch:2909518$$pcerncds:FULLTEXT$$pcerncds:CERN:FULLTEXT$$pcerncds:CERN
002909518 0247_ $$2DOI$$9APS$$a10.1103/PhysRevD.110.112015$$qpublication
002909518 037__ $$9arXiv$$aarXiv:2409.10128$$chep-ex
002909518 037__ $$9arXiv:reportnumber$$aCERN-EP-2024-236
002909518 035__ $$9arXiv$$aoai:arXiv.org:2409.10128
002909518 035__ $$9Inspire$$a2828780
002909518 041__ $$aeng
002909518 088__ $$9CERN-EP-DRAFT-NA64-2024-003
002909518 100__ $$aAndreev, Yu.M.$$jORCID:0000-0002-7397-9665$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 110__ $$aThe NA64 collaboration
002909518 245__ $$9APS$$aShedding light on dark sectors with high-energy muons at the NA64 experiment at the CERN SPS
002909518 260__ $$c2024-12-01
002909518 269__ $$aGeneva$$bCERN$$c10 Sep 2024
002909518 300__ $$a23 p
002909518 506__ $$mcds-ph-ep-publications-referee-non-lhc [CERN]
002909518 520__ $$aA search for Dark Sectors is performed using the unique M2 beam line at the CERN Super Proton Synchrotron. New particles ($X$) could be produced in the bremsstrahlung-like reaction of high energy 160 GeV muons impinging on an active target, $\mu N\rightarrow\mu NX$, followed by their decays, $X\rightarrow\text{invisible}$. The experimental signature would be a scattered single muon from the target, with about less than half of its initial energy and no activity in the sub-detectors located downstream the interaction point. The full sample of the 2022 run is analyzed through the missing energy/momentum channel, with a total statistics of $(1.98\pm0.02)\times10^{10}$ muons on target. We demonstrate that various muon-philic scenarios involving different types of mediators, such as scalar or vector particles, can be probed simultaneously with such a technique. For the vector-case, besides a $L_\mu-L_\tau$ $Z'$ vector boson, we also consider an invisibly decaying dark photon ($A'\rightarrow\text{invisible}$). This search is complementary to NA64 running with electrons and positrons, thus, opening the possibility to expand the exploration of the thermal light dark matter parameter space by combining the results obtained with the three beams.
002909518 520__ $$9APS$$aA search for dark sectors is performed using the unique M2 beam line at the CERN Super Proton Synchrotron. New particles (<math display="inline"><mi>X</mi></math>) could be produced in the bremsstrahlung-like reaction of high-energy 160 GeV positively charged muons impinging on an active target, <math display="inline"><mi>μ</mi><mi>N</mi><mo stretchy="false">→</mo><mi>μ</mi><mi>N</mi><mi>X</mi></math>, followed by their decays, <math display="inline"><mi>X</mi><mo stretchy="false">→</mo><mtext>invisible</mtext></math>. The experimental signature would be a scattered single muon from the target, with about less than half of its initial energy and no activity in the subdetectors located downstream from the interaction point. The full sample of the 2022 run is analyzed through the missing-energy/momentum channel, with total statistics of <math display="inline"><mo stretchy="false">(</mo><mn>1.98</mn><mo>±</mo><mn>0.02</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mn>10</mn></msup></math> muons on target. We demonstrate that various muonphilic scenarios involving different types of mediators, such as scalar or vector particles, can be probed simultaneously with such a technique. For the vector case, besides a <math display="inline"><msub><mi>L</mi><mi>μ</mi></msub><mo>-</mo><msub><mi>L</mi><mi>τ</mi></msub></math> <math display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> vector boson, we also consider an invisibly decaying dark photon (<math display="inline"><msup><mi>A</mi><mo>′</mo></msup><mo stretchy="false">→</mo><mtext>invisible</mtext></math>). This search is complementary to NA64 running with electrons and positrons, thus opening the possibility to expand the exploration of the thermal light dark matter parameter space by combining the results obtained with the three beams.
002909518 520__ $$9arXiv$$aA search for Dark Sectors is performed using the unique M2 beam line at the CERN Super Proton Synchrotron. New particles ($X$) could be produced in the bremsstrahlung-like reaction of high energy 160 GeV muons impinging on an active target, $\mu N\rightarrow\mu NX$, followed by their decays, $X\rightarrow\text{invisible}$. The experimental signature would be a scattered single muon from the target, with about less than half of its initial energy and no activity in the sub-detectors located downstream the interaction point. The full sample of the 2022 run is analyzed through the missing energy/momentum channel, with a total statistics of $(1.98\pm0.02)\times10^{10}$ muons on target. We demonstrate that various muon-philic scenarios involving different types of mediators, such as scalar or vector particles, can be probed simultaneously with such a technique. For the vector-case, besides a $L_\mu-L_\tau$$Z'$ vector boson, we also consider an invisibly decaying dark photon ($A'\rightarrow\text{invisible}$). This search is complementary to NA64 running with electrons and positrons, thus, opening the possibility to expand the exploration of the thermal light dark matter parameter space by combining the results obtained with the three beams.
002909518 540__ $$3Preprint$$aCC-BY-4.0$$uhttps://creativecommons.org/licenses/by/4.0/
002909518 540__ $$3Publication$$aCC BY 4.0$$fSCOAP3$$uhttps://creativecommons.org/licenses/by/4.0/
002909518 542__ $$3Preprint$$dCERN$$g2024
002909518 542__ $$3Publication$$dauthors$$g2024
002909518 562__ $$cPublic comments
002909518 595__ $$aCERN EDS
002909518 6531_ $$9CERN$$aexotics
002909518 65017 $$2SzGeCERN$$aParticle Physics - Experiment
002909518 6531_ $$9CERN$$aparticle and resonance production
002909518 6531_ $$9CERN$$aexperimental results
002909518 6531_ $$9CERN$$aDark Matter
002909518 6531_ $$9CERN$$aDark Sectors
002909518 6531_ $$9CERN$$aFixed target experiment
002909518 6531_ $$9CERN$$aMuon beam
002909518 690C_ $$aCERN
002909518 690C_ $$aARTICLE
002909518 693__ $$aCERN SPS$$eNA64
002909518 700__ $$aBanerjee, D.$$jORCID:0000-0003-0531-1679$$uCERN$$vCERN, European Organization for Nuclear Researchhttps://ror.org/01ggx4157, CH-1211 Geneva, Switzerland
002909518 700__ $$aBanto Oberhauser, B.$$jORCID:0009-0006-4795-1008$$uZurich, ETH$$vETH Zürichhttps://ror.org/05a28rw58, Institute for Particle Physics and Astrophysics, CH-8093 Zürich, Switzerland
002909518 700__ $$aBernhard, J.$$jORCID:0000-0001-9256-971X$$uCERN$$vCERN, European Organization for Nuclear Researchhttps://ror.org/01ggx4157, CH-1211 Geneva, Switzerland
002909518 700__ $$aBisio, P.$$jORCID:0009-0006-8677-7495$$uKobe U.$$uINFN, Genoa$$vUniversità degli Studi di Genova, 16126 Genova, Italia$$vINFN, Sezione di Genova, 16147 Genova, Italia
002909518 700__ $$aCharitonidis, N.$$jORCID:0000-0001-9506-1022$$uCERN$$vCERN, European Organization for Nuclear Researchhttps://ror.org/01ggx4157, CH-1211 Geneva, Switzerland
002909518 700__ $$aCrivelli, P.$$jORCID:0000-0001-5430-9394$$uZurich, ETH$$vETH Zürichhttps://ror.org/05a28rw58, Institute for Particle Physics and Astrophysics, CH-8093 Zürich, Switzerland
002909518 700__ $$aDepero, E.$$jORCID:0000-0003-2239-1746$$uZurich, ETH$$vETH Zürichhttps://ror.org/05a28rw58, Institute for Particle Physics and Astrophysics, CH-8093 Zürich, Switzerland
002909518 700__ $$aDermenev, A.V.$$jORCID:0000-0001-5619-376X$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aDonskov, S.V.$$jORCID:0000-0002-3988-7687$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aDusaev, R.R.$$jORCID:0000-0002-6147-8038$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aEnik, T.$$jORCID:0000-0002-2761-9730$$uUnlisted$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aFrolov, V.N.$$uUnlisted$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aGardikiotis, A.$$jORCID:0000-0002-4435-2695$$uPatras U.$$vPhysics Department, University of Patras, 265 04 Patras, Greece
002909518 700__ $$aGertsenberger, S.V.$$jORCID:0009-0006-1640-9443$$uUnlisted$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aGirod, S.$$uCERN$$vCERN, European Organization for Nuclear Researchhttps://ror.org/01ggx4157, CH-1211 Geneva, Switzerland
002909518 700__ $$aGninenko, S.N.$$jORCID:0000-0001-6495-7619$$uUnlisted$$uUnlisted, CL$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN$$vCenter for Theoretical and Experimental Particle Physics, Facultad de Ciencias Exactas, Universidad Andres Bello, Fernandez Concha 700, Santiago, Chile
002909518 700__ $$aHösgen, M.$$uBonn U., HISKP$$vUniversität Bonn, Helmholtz-Institut für Strahlen-und Kernphysik, 53115 Bonn, Germany
002909518 700__ $$aJoosten, R.$$uBonn U.$$vRheinische Friedrich-Wilhelms-Universität, Bonn, Germany
002909518 700__ $$aKachanov, V.A.$$jORCID:0000-0002-3062-010X$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aKambar, Y.$$jORCID:0009-0000-9185-2353$$uUnlisted$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aKarneyeu, A.E.$$jORCID:0000-0001-9983-1004$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aKasianova, E.A.$$uUnlisted$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aKekelidze, G.$$jORCID:0000-0002-5393-9199$$uUnlisted$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aKetzer, B.$$jORCID:0000-0002-3493-3891$$uBonn U., HISKP$$vUniversität Bonn, Helmholtz-Institut für Strahlen-und Kernphysik, 53115 Bonn, Germany
002909518 700__ $$aKirpichnikov, D.V.$$jORCID:0000-0002-7177-077X$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aKirsanov, M.M.$$jORCID:0000-0002-8879-6538$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aKolosov, V.N.$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aKramarenko, V.A.$$jORCID:0000-0002-8625-5586$$uUnlisted$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aKravchuk, L.V.$$jORCID:0000-0001-8631-4200$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aKrasnikov, N.V.$$jORCID:0000-0002-8717-6492$$uUnlisted$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aKuleshov, S.V.$$jORCID:0000-0002-3065-326X$$uUnlisted, CL$$uChile U., Santiago$$vCenter for Theoretical and Experimental Particle Physics, Facultad de Ciencias Exactas, Universidad Andres Bello, Fernandez Concha 700, Santiago, Chile$$vMillennium Institute for Subatomic Physics at High-Energy Frontier (SAPHIR), Fernandez Concha 700, Santiago, Chile
002909518 700__ $$aLyubovitskij, V.E.$$jORCID:0000-0001-7467-572X$$uUnlisted$$uSanta Maria U., Valparaiso$$uChile U., Santiago$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN$$vMillennium Institute for Subatomic Physics at High-Energy Frontier (SAPHIR), Fernandez Concha 700, Santiago, Chile$$vUniversidad Técnica Federico Santa María and CCTVal, 2390123 Valparaíso, Chile
002909518 700__ $$aLysan, V.$$jORCID:0009-0004-1795-1651$$uUnlisted$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aMatveev, V.A.$$jORCID:0000-0002-2745-5908$$uUnlisted$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aFredes, R. Mena$$uChile U., Santiago$$uSanta Maria U., Valparaiso$$vMillennium Institute for Subatomic Physics at High-Energy Frontier (SAPHIR), Fernandez Concha 700, Santiago, Chile$$vUniversidad Técnica Federico Santa María and CCTVal, 2390123 Valparaíso, Chile
002909518 700__ $$aYanssen, R.G. Mena$$uChile U., Santiago$$uSanta Maria U., Valparaiso$$vMillennium Institute for Subatomic Physics at High-Energy Frontier (SAPHIR), Fernandez Concha 700, Santiago, Chile$$vUniversidad Técnica Federico Santa María and CCTVal, 2390123 Valparaíso, Chile
002909518 700__ $$aBueno, L. Molina$$jORCID:0000-0001-9720-9764$$uValencia U., IFIC$$vInstituto de Fisica Corpuscular (CSIC/UV), Carrer del Catedratic Jose Beltran Martinez, 2, 46980 Paterna, Valencia, Spain
002909518 700__ $$aMongillo, M.$$jORCID:0009-0000-7331-4076$$uZurich, ETH$$vETH Zürichhttps://ror.org/05a28rw58, Institute for Particle Physics and Astrophysics, CH-8093 Zürich, Switzerland
002909518 700__ $$aPeshekhonov, D.V.$$jORCID:0009-0008-9018-5884$$uUnlisted$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aPolyakov, V.A.$$jORCID:0000-0001-5989-0990$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aRadics, B.$$jORCID:0000-0002-8978-1725$$uYork U., Canada$$vYork University, Toronto, Ontario, Canada
002909518 700__ $$aSalamatin, K.M.$$jORCID:0000-0001-6287-8685$$uUnlisted$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aSamoylenko, V.D.$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aShchukin, D.A.$$jORCID:0009-0007-5508-3615$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aSoto, O.$$uLa Serena U.$$uChile U., Santiago$$vDepartamento de Fisica, Facultad de Ciencias, Universidad de La Serena, Avenida Cisternas 1200, La Serena, Chile$$vMillennium Institute for Subatomic Physics at High-Energy Frontier (SAPHIR), Fernandez Concha 700, Santiago, Chile
002909518 700__ $$aSieber, H.$$jORCID:0000-0003-1476-4258$$uZurich, ETH$$vETH Zürichhttps://ror.org/05a28rw58, Institute for Particle Physics and Astrophysics, CH-8093 Zürich, Switzerland
002909518 700__ $$aTikhomirov, V.O.$$jORCID:0000-0002-9634-0581$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aTlisova, I.V.$$jORCID:0000-0003-1552-2015$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aToropin, A.N.$$jORCID:0000-0002-2106-4041$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aTuzi, M.$$jORCID:0009-0000-6276-1401$$uValencia U., IFIC$$vInstituto de Fisica Corpuscular (CSIC/UV), Carrer del Catedratic Jose Beltran Martinez, 2, 46980 Paterna, Valencia, Spain
002909518 700__ $$aVeit, B.M.$$uMainz U., Inst. Phys.$$vJohannes Gutenberg Universitaet Mainz, Mainz, Germany
002909518 700__ $$aVolkov, P.V.$$jORCID:0000-0002-7668-3691$$uUnlisted$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 700__ $$aVolkov, V.Yu.$$jORCID:0009-0005-3500-5121$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aVoronchikhin, I.V.$$jORCID:0000-0003-3037-636X$$uUnlisted$$vAuthors affiliated with an institute covered by a cooperation agreement with CERN
002909518 700__ $$aZamora-Saá, J.$$jORCID:0000-0002-5030-7516$$uUnlisted, CL$$uChile U., Santiago$$vCenter for Theoretical and Experimental Particle Physics, Facultad de Ciencias Exactas, Universidad Andres Bello, Fernandez Concha 700, Santiago, Chile$$vMillennium Institute for Subatomic Physics at High-Energy Frontier (SAPHIR), Fernandez Concha 700, Santiago, Chile
002909518 700__ $$aZhevlakov, A.S.$$jORCID:0000-0002-7775-5917$$uUnlisted$$vAuthors affiliated with an international laboratory covered by a cooperation agreement with CERN
002909518 710__ $$5PH
002909518 710__ $$gNA64 Collaboration
002909518 773__ $$c112015$$mpublication$$n11$$pPhys. Rev. D$$v110$$y2024
002909518 859__ [email protected]
002909518 8564_ $$82556509$$s3876438$$uhttps://cds.cern.ch/record/2909518/files/CERN-EP-2024-236.pdf
002909518 8564_ $$82555976$$s3876438$$uhttps://cds.cern.ch/record/2909518/files/CERN-EP-DRAFT-NA64-2024-003 - draft.pdf$$yDraft (restricted)$$zStamped by WebSubmit: 13/09/2024
002909518 8564_ $$82557046$$s20797$$uhttps://cds.cern.ch/record/2909518/files/ECAL_MC_Data.png$$y00014 Distributions of energy deposited around the MIP peak compatible with a muon for both data (blue triangle) and MC (solid magenta line) in the calibration trigger configuration. Left: The ECAL module. Right: The whole HCAL module (first and second HCAL modules). The spectra are normalized to a similar number of events.
002909518 8564_ $$82557047$$s32000$$uhttps://cds.cern.ch/record/2909518/files/figure_g_2_vector_projection_v1.png$$y00020 The NA64$\mu$ 90\% C.L. exclusion limits in the parameter space compatible with a light boson as an explanation for the muon $(g-2)_\mu$. Left: The $Z'$ vector boson parameter space $(m_{Z'},\ g_{Z'})$ together with existing constraints from neutrino experiments such as BOREXINO \cite{Kamada:2015era,Kaneta:2016uyt,Gninenko:2020xys} and CCFR \cite{Altmannshofer:2014pba,CCFR:1991lpl}, visible searches in electron-positron annihilation with BaBar \cite{Capdevilla:2021kcf}, Belle II constraints \cite{Belle-II:2019qfb} and the NA64 electron program limits \cite{Andreev:2024lps}. Projections for the pre-LS3, pre-LS4, and post-LS4 phases of the muon program are shown together with the $M^{3}$ missing momentum searches \cite{Kahn:2018cqs}. Right: The $S$ scalar boson parameter space $(m_{S},\ g_{S})$ together with existing constraints from BaBar and projections for the pre-LS3, pre-LS4, and post-LS4 phases of the muon program, as well as ATLAS HL-LHC \cite{Galon:2019owl} and $M^{3}$.
002909518 8564_ $$82557048$$s43676$$uhttps://cds.cern.ch/record/2909518/files/figure_dp_thermal_projection_v1.png$$y00025 The NA64$\mu$ 90\% C.L. exclusion limits on the dark photon scenario, $A'\rightarrow\text{invisible}$ in the $(m_{\chi},\ y)$ parameter space, together with the DM target relic abundance for scalar, (pseudo-)Dirac and Majorana scenarios \cite{Berlin:2018bsc}. Left: Scenario with $\alpha_D=0.1$. Right: Scenario with $\alpha_D=0.5$. Projections for the pre-LS3, pre-LS4, and post-LS4 periods are shown for completeness. The combined projected limits (green dashed curve) for NA64$e^{-},e^{+},\mu$ are plotted, using the projections for $10^{13}$ EOT and $10^{11}$ $e^{+}$OT.
002909518 8564_ $$82557049$$s24785$$uhttps://cds.cern.ch/record/2909518/files/dsdpsi-sample-WW-10MeV.png$$y00006 The muon emission angles $\psi_{\mu}^\prime$ for kinematical regimes with $m_{Z'}=10,500$ MeV. The normalized sampled angle (crosses) and the normalized target partial distribution function (PDF, lines) are shown for comparison. Small deviations from the target PDF at larger $\psi_\mu^\prime$ are due to fewer statistics in the binned sample distribution.
002909518 8564_ $$82557050$$s21158$$uhttps://cds.cern.ch/record/2909518/files/HCAL_MC_Data2.png$$y00015 Distributions of energy deposited around the MIP peak compatible with a muon for both data (blue triangle) and MC (solid magenta line) in the calibration trigger configuration. Left: The ECAL module. Right: The whole HCAL module (first and second HCAL modules). The spectra are normalized to a similar number of events.
002909518 8564_ $$82557051$$s28074$$uhttps://cds.cern.ch/record/2909518/files/figure_dp_g_2_projection_v1.png$$y00024 The NA64$\mu$ 90\% C.L. exclusion limits on the dark photon scenario, $A'\rightarrow\text{invisible}$. The $(m_{A'},\ \epsilon)$ parameter space is shown, together with the latest results from NA64$e^{-}$ \cite{NA64:2023wbi} and NA64$e^{+}$ \cite{NA64:2023ehh} and the existing limits from BaBar \cite{BaBar:2017tiz}. The peak is related to fermionic DM assuming $\alpha_D=0.1$. Projections for the pre-LS3, pre-LS4, and post-LS4 periods are shown.
002909518 8564_ $$82557052$$s27600$$uhttps://cds.cern.ch/record/2909518/files/figure_g_2_dm_scalar_v1.png$$y00027 The NA64$\mu$ 90\% C.L. exclusion limits on invisibly decaying spin-0 scalar mediator, $S\rightarrow\text{invisible}$. The thermal targets for light DM are shown for respectively $m_S/m_\chi=3$ and $m_S/m_\chi=2.1$ with $g_\chi=1$, and extracted from \cite{Chen:2018vkr}. Projections for $3\times10^{11}$, $2\times10^{13}$ and $10^{14}$ MOT are plotted.
002909518 8564_ $$82557053$$s34903$$uhttps://cds.cern.ch/record/2909518/files/HCAL_transverse.png$$y00009 Energy distributions for both HCAL and ECAL from secondary products from hard muon bremsstrahlung and nuclear interactions in the target. A final-state muon with energy less than $E_\mu^\prime\leq100$ GeV is required. Both HCAL transverse sizes with 60$\times$60 cm$^2$ (blue) and $120\times60$ cm$^2$ (red) are shown. The upper bound of the signal box (black dashed line) is shown (see Sec. \ref{sec:data-analysis}).
002909518 8564_ $$82557054$$s6954$$uhttps://cds.cern.ch/record/2909518/files/total-cs-G4-DMG4-brem.png$$y00005 Left: Distributions of the fractional energy, $x$, for repsectively SM muon bremsstrahlung, $\mu N\rightarrow\mu N\gamma$ and dark bremsstrahlung in the limit $m_{Z'}\rightarrow0$. The events are obtained from a minimal \texttt{GEANT4} simulation of the NA64$\mu$ target, assuming a fixed muon beam energy $E_0=160$ GeV. Right: Production cross-sections $\sigma_{2\rightarrow3}$ as a function of the muon beam energy, $E_0$, extracted from a realistic \texttt{GEANT4} simulation of both SM muon bremsstrahlung, $\mu N\rightarrow\mu N\gamma$, and dark bremsstrahlung in the limit $m_{Z'}\rightarrow0$, within the NA64$\mu$ ECAL.
002909518 8564_ $$82557055$$s18350$$uhttps://cds.cern.ch/record/2909518/files/hermeticity_allcuts.png$$y00011 Event distribution in the hermeticity plane defined by the reconstructed momentum after the ECAL target, $p_\text{out}$, and the sum of energy deposit in the calorimeters, $E_\text{CAL}=E_\text{ECAL}+E_\text{VHCAL}+E_\text{HCAL}$ \cite{Andreev:2024sgn}. The sample of events corresponds to the sum of both physical trigger configurations 1+2, with $N_\text{MOT}=(1.98\pm0.02)\times10^{10}$. The signal region is blinded (green right-hashed box). Left: Events distribution after applying selection criteria (i-ii) to select a single-track-compatible event with a muon traversing the whole set-up. For completeness, different regions of the phase space are highlighted, with regions $A$ and $B$ used as \emph{control} regions for background extrapolation (see text). Right: Event distribution after additionally requiring a MIP in the calorimeters and no activity in the VHCAL and VETO (criteria (i-iii)).
002909518 8564_ $$82557056$$s40204$$uhttps://cds.cern.ch/record/2909518/files/figure_dp05_thermal_projection_v1.png$$y00026 The NA64$\mu$ 90\% C.L. exclusion limits on the dark photon scenario, $A'\rightarrow\text{invisible}$ in the $(m_{\chi},\ y)$ parameter space, together with the DM target relic abundance for scalar, (pseudo-)Dirac and Majorana scenarios \cite{Berlin:2018bsc}. Left: Scenario with $\alpha_D=0.1$. Right: Scenario with $\alpha_D=0.5$. Projections for the pre-LS3, pre-LS4, and post-LS4 periods are shown for completeness. The combined projected limits (green dashed curve) for NA64$e^{-},e^{+},\mu$ are plotted, using the projections for $10^{13}$ EOT and $10^{11}$ $e^{+}$OT.
002909518 8564_ $$82557057$$s24871$$uhttps://cds.cern.ch/record/2909518/files/experimental_sketch_downstream.png$$y00003 The \emph{downstream} region of the experiment for final-state muon identification through detector response and momentum reconstruction in MS2. The distances between the detector elements are given in cm. See text for more details.
002909518 8564_ $$82557058$$s28230$$uhttps://cds.cern.ch/record/2909518/files/figure_g_2_scalar_projection_v1.png$$y00021 The NA64$\mu$ 90\% C.L. exclusion limits in the parameter space compatible with a light boson as an explanation for the muon $(g-2)_\mu$. Left: The $Z'$ vector boson parameter space $(m_{Z'},\ g_{Z'})$ together with existing constraints from neutrino experiments such as BOREXINO \cite{Kamada:2015era,Kaneta:2016uyt,Gninenko:2020xys} and CCFR \cite{Altmannshofer:2014pba,CCFR:1991lpl}, visible searches in electron-positron annihilation with BaBar \cite{Capdevilla:2021kcf}, Belle II constraints \cite{Belle-II:2019qfb} and the NA64 electron program limits \cite{Andreev:2024lps}. Projections for the pre-LS3, pre-LS4, and post-LS4 phases of the muon program are shown together with the $M^{3}$ missing momentum searches \cite{Kahn:2018cqs}. Right: The $S$ scalar boson parameter space $(m_{S},\ g_{S})$ together with existing constraints from BaBar and projections for the pre-LS3, pre-LS4, and post-LS4 phases of the muon program, as well as ATLAS HL-LHC \cite{Galon:2019owl} and $M^{3}$.
002909518 8564_ $$82557059$$s43267$$uhttps://cds.cern.ch/record/2909518/files/hermeticity_regions.png$$y00010 Event distribution in the hermeticity plane defined by the reconstructed momentum after the ECAL target, $p_\text{out}$, and the sum of energy deposit in the calorimeters, $E_\text{CAL}=E_\text{ECAL}+E_\text{VHCAL}+E_\text{HCAL}$ \cite{Andreev:2024sgn}. The sample of events corresponds to the sum of both physical trigger configurations 1+2, with $N_\text{MOT}=(1.98\pm0.02)\times10^{10}$. The signal region is blinded (green right-hashed box). Left: Events distribution after applying selection criteria (i-ii) to select a single-track-compatible event with a muon traversing the whole set-up. For completeness, different regions of the phase space are highlighted, with regions $A$ and $B$ used as \emph{control} regions for background extrapolation (see text). Right: Event distribution after additionally requiring a MIP in the calorimeters and no activity in the VHCAL and VETO (criteria (i-iii)).
002909518 8564_ $$82557060$$s8671$$uhttps://cds.cern.ch/record/2909518/files/experimental_sketch_upstream.png$$y00002 Experimental set-up schematic overview of the search for $Z^\prime\rightarrow\text{invisible}$ \cite{Andreev:2024sgn}. Top: The \emph{upstream} experimental region for the reconstruction of the incoming muon momentum through the MS1 (BEND6) magnet spectrometer using MM$_{1-4}$, ST$_{5,4}$ and BMS$_{1-6}$. The beam-defining optics quadrupoles, QPL$_{29-32}$ and QPL$_{33}$, part of the FODO scheme, are shown. For completeness, the distances between the different detector elements are given in cm. See text for more details.
002909518 8564_ $$82557061$$s14557$$uhttps://cds.cern.ch/record/2909518/files/diffcs-G4-DMG4-brem.png$$y00004 Left: Distributions of the fractional energy, $x$, for repsectively SM muon bremsstrahlung, $\mu N\rightarrow\mu N\gamma$ and dark bremsstrahlung in the limit $m_{Z'}\rightarrow0$. The events are obtained from a minimal \texttt{GEANT4} simulation of the NA64$\mu$ target, assuming a fixed muon beam energy $E_0=160$ GeV. Right: Production cross-sections $\sigma_{2\rightarrow3}$ as a function of the muon beam energy, $E_0$, extracted from a realistic \texttt{GEANT4} simulation of both SM muon bremsstrahlung, $\mu N\rightarrow\mu N\gamma$, and dark bremsstrahlung in the limit $m_{Z'}\rightarrow0$, within the NA64$\mu$ ECAL.
002909518 8564_ $$82557062$$s39914$$uhttps://cds.cern.ch/record/2909518/files/figure_gchi_5e-2_projection_v1.png$$y00022 The NA64$\mu$ 90\% C.L. exclusion limits in the LTDM parameter space $y-m_{\chi}$ compatible with an invisibly decaying $Z'\rightarrow\text{DM}$ with (left) $g_\chi=5\times10^{-2}$ and (right) $g_\chi=1$ and mass ratio $m_\chi/m_{Z'}=3$. The existing constraints from the CCFR experiment \cite{Altmannshofer:2014pba,CCFR:1991lpl} are compared, and the thermal targets for complex scalar, (pseudo-)Dirac and Majorana thermal relics plotted \cite{Berlin:2018bsc}. Projections for the pre-LS3, pre-LS4, and post-LS4 periods of the muon program are shown together with the $M^{3}$ missing momentum searches \cite{Kahn:2018cqs}. The NA64 electron program limits are plotted for completeness \cite{Andreev:2024lps}.
002909518 8564_ $$82557063$$s24094$$uhttps://cds.cern.ch/record/2909518/files/deflection_ms2.png$$y00013 Distribution of single-track muon events deflection past MS2, defined as $\delta x=(\text{MM}_7)_{x}-(\text{GEM}_1)_x$, for both data (blue triangle) and MC (solid magenta line) in the calibration trigger configuration.
002909518 8564_ $$82557064$$s10058$$uhttps://cds.cern.ch/record/2909518/files/decay_spectrum.png$$y00017 Final-state muon energy distributions for both pions (green line) and kaons (blue line) decays, $\pi,K\rightarrow\mu+X$, as extracted from a dedicated \texttt{GEANT4} simulation of the process within the experimental set-up.
002909518 8564_ $$82557065$$s25681$$uhttps://cds.cern.ch/record/2909518/files/momentum_extrap_v1.png$$y00018 Exponential (dashed magenta line) and Crystal Ball (dashed green line) fits of the low-energy tails of the scattered muon momentum distribution, after applying selection criteria (iii) and (i), with $p_\text{in}=160\pm10$ GeV/c, on a sample of events extracted from the calibration trigger configuration.
002909518 8564_ $$82557066$$s33852$$uhttps://cds.cern.ch/record/2909518/files/figure_gchi_1_projection_v1.png$$y00023 The NA64$\mu$ 90\% C.L. exclusion limits in the LTDM parameter space $y-m_{\chi}$ compatible with an invisibly decaying $Z'\rightarrow\text{DM}$ with (left) $g_\chi=5\times10^{-2}$ and (right) $g_\chi=1$ and mass ratio $m_\chi/m_{Z'}=3$. The existing constraints from the CCFR experiment \cite{Altmannshofer:2014pba,CCFR:1991lpl} are compared, and the thermal targets for complex scalar, (pseudo-)Dirac and Majorana thermal relics plotted \cite{Berlin:2018bsc}. Projections for the pre-LS3, pre-LS4, and post-LS4 periods of the muon program are shown together with the $M^{3}$ missing momentum searches \cite{Kahn:2018cqs}. The NA64 electron program limits are plotted for completeness \cite{Andreev:2024lps}.
002909518 8564_ $$82557067$$s24861$$uhttps://cds.cern.ch/record/2909518/files/signal_efficiency.png$$y00019 Effect of the geometrical acceptance associated with trigger 1 (S$_4$ and S$_\mu$ shifted respectively 65 mm and 152 mm along the magnetic deflection direction) on the signal efficiency computed as a function of the mass. The track reconstruction efficiency is also considered.
002909518 8564_ $$82557068$$s3600803$$uhttps://cds.cern.ch/record/2909518/files/2409.10128.pdf$$yFulltext
002909518 8564_ $$82557069$$s23909$$uhttps://cds.cern.ch/record/2909518/files/hcal0_trigger1.png$$y00016 First HCAL module energy distribution for a sample of muon interacting in the ECAL, $\mu N\rightarrow\mu+X$, with high energetic secondaries escaping the detector and propagating through MS2. Both data (blue triangle) and MC (solid magenta line) correspond to the physics trigger configuration 1. The spectra are normalized to a similar number of events. See text for more details.
002909518 8564_ $$82557070$$s35258$$uhttps://cds.cern.ch/record/2909518/files/GENFIT.rendering.png$$y00012 \texttt{GenFit}-based \cite{Rauch:2014wta} track reconstruction through the whole experimental set-up.
002909518 8564_ $$82557071$$s8546$$uhttps://cds.cern.ch/record/2909518/files/total-ratio-WW-ETL-vector.png$$y00000 Ratio of the cross-sections computed in the WW approximation and at ETL, $\sigma_{2\rightarrow3}^{Z'}\big|_\text{WW}/\sigma_{2\rightarrow3}^{Z'}\big|_\text{ETL}$, as a function of the muon beam energy, $E_0$, for different $Z'$ masses, $m_{Z'}$. More details can be found in \cite{Kirpichnikov:2021jev}.
002909518 8564_ $$82557072$$s11455$$uhttps://cds.cern.ch/record/2909518/files/calibration_optimisation.png$$y00007 Calibration trigger acceptance effects (blue solid line) on the initial-state beam muons before the ECAL target.
002909518 8564_ $$82557073$$s17330$$uhttps://cds.cern.ch/record/2909518/files/dsdx-BREM-IWW-WW-ETL-vector.png$$y00001 Comparison of the single-differential cross-section as a function of the fractional energy of the emitted $\gamma$ and $Z'$ through respectively SM muon-bremsstrahlung and dark bremsstrahlung, $\mu N\rightarrow\mu NZ'$, in the mass limit $m_{Z'}\rightarrow0$. These results are obtained both at ETL and in the WW and IWW approaches, with mixing strength $\epsilon_{Z'}=g_{Z'}/e=1$. More details can be found in Ref. \cite{Kirpichnikov:2021jev}.
002909518 8564_ $$82557074$$s13200$$uhttps://cds.cern.ch/record/2909518/files/s4_brem_optimisation.png$$y00008 Final-state muons energy distribution from the SM process $\mu N\rightarrow\mu N\gamma$ using the calibration trigger configuration (green line) and different physical trigger configurations with the S$_4$ counter shifted respectively -40 mm (black line) and -65 mm (blue line) along the deflection axis past MS2. For completeness, bremsstrahlung-like events $\mu N\rightarrow\mu NZ'$ in the $m_{Z'}=1$ MeV scenario (solid red dots) are shown for S$_4$ at -65 mm.
002909518 8564_ $$82705118$$s1979491$$uhttps://cds.cern.ch/record/2909518/files/Publication.pdf$$yFulltext
002909518 9031_ $$aApproval requested for number CERN-EP-2024-236$$bCERN-EP-2024-236$$cEPPHAPP$$d2024-09-10 15:41:14$$e2024-09-12 15:41:[email protected]$$swaiting
002909518 9031_ $$aDocument approved$$bCERN-EP-2024-236$$cEPPHAPP$$d2024-09-13 13:53:[email protected]$$sapproved
002909518 916__ $$sn$$w202437
002909518 980__ $$aNA64_Papers
002909518 980__ $$aARTICLE