Coherent Elastic Neutrino Nucleus Scattering (CEνNS) is a novel technique to look for new physics beyond the Standard Model. We study the prospects of probing a transition magnetic moment in CEνNS experiments. Showing the NUCLEUS experiment as an example, we demonstrate that properties of a potential sterile neutrino can be deduced

Bolton, PD

Deppisch, FF

Fridell, K

Harz, J

Hati, C

Kulkarni, S

English

UCL Discovery

Journal of Physics: Conference SeriesPAPER • OPEN ACCESSTransition neutrino magnetic moments in CEvNSTo cite this article: Patrick D. Bolton et al 2021 J. Phys.: Conf. Ser. 2156 012218 View the article online for updates and enhancements.You may also likeComparative Analysis of GenderDifferences in Environmental Values ofChinese PeopleNingning Wu, Shuai Wang, Xiao Liang etal.-Community cooling infrastructure fromwaste heat among diverse building typesin Rourkela Steel Township, IndiaR Sen, E Teitelbaum and F Meggers-The comparison of velaroidal shellstructures of square plane load bearingpropertiesE Tupikova and M Berdiev-This content was downloaded from IP address 193.60.238.99 on 06/07/2022 at 16:17Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing Ltd17th International Conference on Topics in Astroparticle and Underground PhysicsJournal of Physics: Conference Series 2156 (2022) 012218IOP Publishingdoi:10.1088/1742-6596/2156/1/0122181Transition neutrino magnetic moments in CEνNSPatrick D. Bolton1,2, Frank F. Deppisch1, K̊are Fridell∗3, Julia Harz3,Chandan Hati3 and Suchita Kulkarni41Department of Physics and Astronomy, University College London, London WC1E 6BT,United Kingdomy2SISSA, International School for Advanced Studies, INFN, Sezione di Trieste, Via Bonomea265, I-34136 Trieste, Italy3Physik Department T70, Technische Universität München, James-Franck-Straße 1, D-85748Garching, Germany4Institute of Physics, NAWI Graz, University of Graz, Universitätsplatz 5, A-8010 Graz,AustriaE-mail: kare.fridell@tum.deAbstract. Coherent Elastic Neutrino Nucleus Scattering (CEνNS) is a novel technique to lookfor new physics beyond the Standard Model. We study the prospects of probing a transitionmagnetic moment in CEνNS experiments. Showing the NUCLEUS experiment as an example,we demonstrate that properties of a potential sterile neutrino can be deduced.1. IntroductionCoherent neutrino nucleus scattering (CEνNS) was observed for the first time at theCOHERENT experiment in 2017 [1]. One of the major difficulties in observing such scatteringsis the smallness of the nuclear recoil that is induced, with recoil energies being in the keV range.The near-future a experiment NUCLEUS [2, 3], located at the CHOOZ nuclear site in France,aims to reach a sensitivity to nuclear recoils in the O(10) eV range.After the first observation of CEνNS, the novelty in CEνNS experiments has shifted fromconfirming the existence of this process, which is predicted by the Standard Model (SM), tousing it as an observable to constrain neutrino oscillation parameters [4, 5] or search for NewPhysics (NP) beyond the SM (BSM) [6–11]. A possible BSM scenario that could induce asignal in CEνNS experiments is the existence of an enhanced neutrino magnetic moment. Thismagnetic moment, connecting neutrinos with photons, can provide an additional interactionchannel between neutrinos and nuclei, thereby enhancing the CEνNS signal.One further possibility is that one of the fermions participating in the magnetic momentvertex is sterile neutrino N , which can be of either Dirac or Majorana nature, rather than anactive SM neutrino ναL. Such a vertex can be realized by the LagrangianL ⊃ µανN ν̄αLσµνPRNFµν + h.c. , (1)where Fµν = ∂µAν−∂νAµ is the field strength tensor corresponding to the electromagnetic fieldAµ. The terms in Eq. (1) correspond to dimension 5 effective field theory (EFT) operators, thatcan be UV-completed in for example renormalisable inverse see-saw models, for both Dirac andMajorana active neutrinos [12,13].∗Speaker17th International Conference on Topics in Astroparticle and Underground PhysicsJournal of Physics: Conference Series 2156 (2022) 012218IOP Publishingdoi:10.1088/1742-6596/2156/1/0122182ν NγµνNν νAγANγµνN µνNFigure 1. Left: Neutrino transition magnetic moment vertex. Right: Primakoff upscatteringof a neutrino ν to a sterile neutrino N via a nucleus A, with subsequent decay of the sterileneutrino to an active neutrino and a photon.The evidence for non-zero neutrino masses, coming from neutrino oscillation experiments [14],motivates the search for sterile neutrinos that could take part in the active neutrino massgeneration mechanism. In case the sterile neutrino is a Majorana particle, the transitionmagnetic moment vertex will also contribute to a radiative neutrino Majorana mass term [6],possibly explaining the origin of active neutrino masses.2. Radiative CEνNSThe transition neutrino magnetic moment, shown in Fig. 1 (left), can lead to Primakoffupscattering in CEνNS events, where an incoming active neutrino transitions into a sterileneutrino in its interaction with the nucleus. Assuming that the sterile neutrino is heavy, it candecay back into an active neutrino and an additional photon via the same vertex that producedthe initial upscattering, as depicted in Fig. 1 (right).In Ref. [6], we proposed a new type of experimental search, where the possibility to detect afinal state photon is present in CEνNS experiments. This could allow for efficient backgroundrejection, while simultaneously a providing new way to search for sterile neutrinos. In such aset-up, a photon detector is placed a distance l0 downstream of a CEνNS target. The sterileneutrinos that decay via the transition magnetic moment before reaching the photon detectorwill emit a photon that can be detected. This requirement of decaying within the experimentalset-up can be accounted for in the effective width of the sterile neutrino ΓN ∝ 1/l0, such thatlonger distances l0 generally lead to a larger proportion of N being able to provide a signal [6].If the nuclear recoil in the upscattering is also recorded, the photon- and nuclear recoil signalsare coincident and can provide a clear signature for these types of radiative CEνNS events.3. ConstraintsThere are numerous constraints on the neutrino transition magnetic moment coupling. Thiscoupling is flavour dependent, and therefore different experiments probe different flavourcouplings (depending on the source of neutrinos in terms of their flavour). For experimentsthat use neutrinos from pion decays, the most stringent constraints are provided for the µ-flavour coupling. Astrophysical observations generally constrain flavour-universally, and moststringently so in the low-mN part of the parameter space.The NUCLEUS experiment uses a nuclear reactor as the source of neutrinos, where electron-flavour antineutrinos are emitted in the β-decays of fission products. Therefore, the relevantconstraints to consider for NUCLEUS are those on the electron-flavour neutrino transitionmagnetic moment coupling µeνN . As shown in Fig. 2, the parameter space of this couplingis constrained by both astrophysical observations and laboratory experiments.The reach of of the near-future NUCLEUS experiment for the radiative CEνNS mode withan active neutrino final state, in the case where final state photon detection is possible and 10g17th International Conference on Topics in Astroparticle and Underground PhysicsJournal of Physics: Conference Series 2156 (2022) 012218IOP Publishingdoi:10.1088/1742-6596/2156/1/0122183Figure 2. Parameter space of the electron flavour neutrino transition magnetic dipole momentµeνN as a function of the sterile neutrino mass mN . The reach of the NUCLEUS experiment forthe radiative CEνNS mode is shown in red solid and dot-dashed lines for the near-future 10gdetector and black solid and dot-dashed lines for the far-future 10 kg upgrade, where solid linesrefer to an active neutrino final state and dot-dashed lines correspond to another sterile fermionN ′ in the final state, assuming a 3 year run time [6]. Existing constraints are shown in colouredareas. Astrophysical constraints come from Borexino, SN1987A, and BBN [15], while laboratoryconstraints come from LSND, LEP [16], and COHERENT [6]. Future projections are shown indashed lines for DUNE near detector [17] and NUCLEUS for Primakoff upscattering [6]. Allconstraints are given at 90% C.L. unless otherwise stated.of target material is used, is within the region excluded by the COHERENT experiment in theparameter space of µeνN and mN , assuming a 3 year run time for NUCLEUS [6]. A possiblefar-future upgrade of NUCLEUS, consisting of 1kg of target material, would have a much greaterreach in the parameter space than the near-future 10g experiment. However, also the regionthat would be explored by the upgrade is excluded by the COHERENT experiment.The exclusion line in Fig. 2 corresponding to the COHERENT experiment assumes thatPrimakoff upscattering via a neutrino transition magnetic moment would cause a deviationfrom the standard CEνNS signal, and since such a deviation is not seen, a part of the relevantparameter space is excluded [6]. Therefore, the process that corresponds to the exclusion linefrom COHERENT includes one instance of the neutrino transition magnetic moment, whilethe exclusion line from NUCLEUS, corresponding to the radiative CEνNS mode, includes twoinstances. Therefore, prime objective in the search for a radiative CEνNS mode is not toconstrain new regions of parameter space, but rather to find the details of a possible signalcoming from Primakoff upscattering. As seen in Ref. [6], the potential Primakoff upscatteringexclusion limit from the near- and far-future NUCLEUS is well within new regions of parameterspace. Furthermore, in the radiative mode, it is possible that the decay of N contains final statefermions N ′ other than the active electron-flavour neutrino, possibly enhancing the experimentalreach of the radiative mode further.4. ConclusionOne possible method to search for NP in the neutrino sector is via CEνNS experiments, where thesterile neutrino could be produced in Primakoff upscattering events. The improved sensitivity17th International Conference on Topics in Astroparticle and Underground PhysicsJournal of Physics: Conference Series 2156 (2022) 012218IOP Publishingdoi:10.1088/1742-6596/2156/1/0122184in the near-future CEνNS experiment NUCLEUS will allow sterile neutrnios with MeV-scalemasses to be probed in regions of parameter spacethat are so far unconstrained [6].The final state photon in radiative CEνNS events could in principle be detected if a photondetector is placed downstream of the CEνNS target [6]. A coincident signal of a final statephoton and a nuclear recoil in the CEνNS target could reduce the background, and help toidentify the process producing the signals.The potential that CEνNS experiments have in providing more details about the propertiesof neutrinos is largely still untapped, due mainly to the novelty of such experiments. Therefore,the future of CEνNS is very exciting, and the next generation of experiments will be crucial inthe development of this relatively new search mode.AcknowledgementsThe authors are grateful to the NUCLEUS collaboration, in particular to B. Mauri, E.Mazzucato, C. Nones, J. Rothe, T. Lasserre, F. Reindl, R. Strauss, M. Vignati for many usefuldiscussions regarding the NUCLEUS experiment. K. F., J. H. and C. H. acknowledge supportfrom the DFG Emmy Noether Grant No. HA 8555/1-1. K. F. acknowledges support from theDFG Collaborative Research Centre “Neutrinos and Dark Matter in Astro- and Particle Physics”(SFB 1258). J. H. acknowledges discussions at the Aspen Center for Physics, supported byNational Science Foundation grant PHY-1607611. P. D. B. and F. F. D. acknowledge supportfrom the UK Science and Technology Facilities Council (STFC) via the Consolidated GrantsST/P00072X/1 and ST/T000880/1. P. D. B. has received support from the European Union’sHorizon 2020 research and innovation programme under the Marie Sk lodowska-Curie grantagreement No 860881-HIDDeN. S. K. is supported by the Austrian Academy of Sciences Elise-Richter grant project number V592-N27.References[1] D. Akimov et al. [COHERENT], Science 357 (2017) no.6356, 1123-1126 doi:10.1126/science.aao0990[arXiv:1708.01294 [nucl-ex]].[2] G. Angloher et al. [NUCLEUS], Eur. Phys. J. C 79 (2019) no.12, 1018 doi:10.1140/epjc/s10052-019-7454-4[arXiv:1905.10258 [physics.ins-det]].[3] J. Rothe et al. [NUCLEUS], J. Low Temp. Phys. 199 (2019) no.1-2, 433-440 doi:10.1007/s10909-019-02283-7[4] P. Coloma and T. Schwetz, Phys. Rev. D 94 (2016) no.5, 055005 [erratum: Phys. Rev. D 95 (2017) no.7,079903] doi:10.1103/PhysRevD.94.055005 [arXiv:1604.05772 [hep-ph]].[5] P. B. Denton, J. Gehrlein and R. Pestes, Phys. Rev. Lett. 126 (2021) no.5, 051801doi:10.1103/PhysRevLett.126.051801 [arXiv:2008.01110 [hep-ph]].[6] P. D. Bolton, F. F. Deppisch, K. Fridell, J. Harz, C. Hati and S. Kulkarni, [arXiv:2110.02233 [hep-ph]].[7] P. Coloma, P. A. N. Machado, I. Martinez-Soler and I. M. Shoemaker, Phys. Rev. Lett. 119 (2017) no.20,201804 doi:10.1103/PhysRevLett.119.201804 [arXiv:1707.08573 [hep-ph]].[8] O. G. Miranda, D. K. Papoulias, M. Tórtola and J. W. F. Valle, JHEP 07 (2019), 103doi:10.1007/JHEP07(2019)103 [arXiv:1905.03750 [hep-ph]].[9] P. S. Bhupal Dev, K. S. Babu, P. B. Denton, P. A. N. Machado, C. A. Argüelles, J. L. Barrow,S. S. Chatterjee, M. C. Chen, A. de Gouvêa and B. Dutta, et al. SciPost Phys. Proc. 2 (2019), 001doi:10.21468/SciPostPhysProc.2.001 [arXiv:1907.00991 [hep-ph]].[10] P. Coloma, I. Esteban, M. C. Gonzalez-Garcia and M. Maltoni, JHEP 02 (2020), 023doi:10.1007/JHEP02(2020)023 [arXiv:1911.09109 [hep-ph]].[11] A. N. Khan, D. W. McKay and W. Rodejohann, Phys. Rev. D 104 (2021) no.1, 015019doi:10.1103/PhysRevD.104.015019 [arXiv:2104.00425 [hep-ph]].[12] R. N. Mohapatra, Phys. Rev. Lett. 56 (1986), 561-563 doi:10.1103/PhysRevLett.56.561[13] R. N. Mohapatra and J. W. F. Valle, Phys. Rev. D 34 (1986), 1642 doi:10.1103/PhysRevD.34.1642[14] P.A. Zyla et al. [Particle Data Group], PTEP 2020 (2020) no.8, 083C01 doi:10.1093/ptep/ptaa104[15] V. Brdar, A. Greljo, J. Kopp and T. Opferkuch, JCAP 01 (2021), 039 doi:10.1088/1475-7516/2021/01/039[arXiv:2007.15563 [hep-ph]].[16] G. Magill, R. Plestid, M. Pospelov and Y. D. Tsai, Phys. Rev. D 98 (2018) no.11, 115015doi:10.1103/PhysRevD.98.115015 [arXiv:1803.03262 [hep-ph]].[17] T. Schwetz, A. Zhou and J. Y. Zhu, JHEP 21 (2020), 200 doi:10.1007/JHEP07(2021)200 [arXiv:2105.09699[hep-ph]].

Transition neutrino magnetic moments in CEνNS

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Transition neutrino magnetic moments in CEνNS

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