Search

In the presence of transition magnetic moments between active and sterile neutrinos, the search for a Primakoff upscattering process at coherent elastic neutrino-nucleus scattering (CE$\nu$NS) experiments can provide stringent constraints on the neutrino magnetic moment. We show that a radiative upscattering process with an emitted photon in the final state can induce a novel coincidence signal at CE$\nu$NS experiments that can also probe neutrino transition magnetic moments beyond existing limits. Furthermore, the differential distributions for such a radiative mode can also potentially be sensitive to the Dirac vs. Majorana nature of the sterile state mediating the process. This can provide valuable insights into the nature and mass generation mechanism of the light active neutrinos., Comment: 38 pages, 9 figures; expanded discussion of constraints, matches published version

Acknowledgments We thank the participants of the FPF meetings and the Snowmass working groups for discussions that have contributed both directly and indirectly to this study. We gratefully acknowledge the invaluable support of the CERN Physics Beyond Colliders study group and the work of CERN technical teams related to civil engineering studies (SCE-DOD), safety discussions (HSE-OHS, HSE-RP, EP-DI-SO), integration (EN-ACE), and discussions on services (EN-CV, EN-EL, EN-AA) and simulations (SY-STI). The work by J Alameddine, W Rhode, T Ruhe, and A Sandrock has been supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), Collaborative Research Center SFB 876 and SFB 1491. L A Anchordoqui is supported by the US National Science Foundation (NSF) Grant PHY-2112527. T Araki is supported by JP18H01210. A Ariga is supported by JSPS KAKENHI Grant JP20K23373 and the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (Grant 101002690). T Ariga acknowledges support from JSPS KAKENHI Grant JP19H01909. K Asai is supported by JSPS KAKENHI Grant JP19J13812 and JP21K20365. A Bacchetta and F G Celiberto acknowledge support from the INFN/NINPHA project. P Bakhti and M Rajaee are supported by the National Research Foundation of Korea (NRF-2020R1I1A3072747). B Barman received funding from the Patrimonio Autónomo—Fondo Nacional de Financiamiento para la Ciencia, la Tecnología y la Innovación Francisco José de Caldas (MinCiencias—Colombia) Grant 80740-465-2020 and the European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement No. 860881-HIDDeN. The work of B Batell is supported by the US Department of Energy (DOE) Grant DE–SC0007914. The work of A Berlin, T J Hobbs, S Hoeche, and J G Morfín was supported by the Fermi National Accelerator Laboratory (Fermilab), a US DOE, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract DE-AC02-07CH11359. M Becker, E Copello and J Harz acknowledge support from the DFG Emmy Noether Grant HA 8555/1-1. E Copello acknowledges also support from the DFG Collaborative Research Centre 'Neutrinos and Dark Matter in Astro- and Particle Physics' (SFB 1258). E Bertuzzo acknowledges financial support from FAPESP Contracts 2015/25884-4 and 2019/15149-6 and is indebted to the Theoretical Particle Physics and Cosmology group at King's College London for hospitality. The work of J Bian and W Wu is supported in part by US DOE Grant DE-SC0009920 and Heising-Simons Foundation Grant 2022-3319. The work of A Boyarsky and M Ovchynnikov is supported by the ERC under the European Union's Horizon 2020 Research and Innovation Programme (GA 694896). A Carmona acknowledges funding from the European Union's Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie Grant Agreement No. 754446 and UGR Research and Knowledge Transfer Found—Athenea3i. A Carmona also acknowledges partial support by the Ministry of Science and Innovation and SRA (10.13039/501100011033) Grant PID2019-106087GB-C22 and by the Junta de Andalucía Grant A-FQM-472-UGR20. F G Celiberto thanks the Università degli Studi di Pavia for the warm hospitality. The work of G Chachamis was supported by the Fundação para a Ciência e a Tecnologia (Portugal) under Project CERN/FIS-PAR/0024/2019 and Contract 'Investigador auxiliar FCT—Individual Call/03216/2017'. The work of M Citron and D Stuart is supported by US DOE Grant DE-SC0011702. The work of L Darme is supported by the European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement 101028626. P B Denton acknowledges support from the US DOE Grant Contract DE-SC0012704. The work of P S Bhupal Dev was supported in part by the US DOE Grant DE-SC0017987. The research activities of K R Dienes were supported in part by the US DOE Grant DE-FG02-13ER41976/DE-SC0009913 and also by the US NSF through its employee IR/D program. M V Diwan acknowledges support from the US DOE Grant Contract DE-SC0012704. Y Du and J H Yu are supported in part by National Key Research and Development Program of China Grant 2020YFC2201501, and the National Science Foundation of China (NSFC) under Grants 12022514, 11875003 and 12047503, and CAS Project for Young Scientists in Basic Research YSBR-006, and the Key Research Program of the CAS Grant XDPB15. The work of B Dutta and S Ghosh are supported in part by the US DOE Grant DE-SC0010813. The work of S Ghosh is also supported in part by National Research Foundation of Korea (NRF)'s Grants, Grant 6N021413. Y Farzan has received financial support from Saramadan Contract ISEF/M/400279 as well as from the European Union's Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie Grant Agreement 860881-HIDDeN. The work of J L Feng is supported in part by US NSF Grants PHY-1915005 and PHY-2111427, Simons Investigator Award #376204, Simons Foundation Grant 623683, and Heising-Simons Foundation Grants 2019-1179 and 2020-1840. M Fieg is supported in part by US NSF Grant PHY-1915005 and by NSF Graduate Research Fellowship Award DGE-1839285. A L Foguel is supported by FAPESP Contract 2020/00174-2. The work of P Foldenauer is supported by the UKRI Future Leaders Fellowship DARKMAP. The work of S Foroughi-Abari and A Ritz is supported in part by NSERC, Canada. The work of J-F Fortin is supported in part by NSERC, Canada. A Friedland is supported by the US DOE Grant DE-AC02-76SF00515. E Fuchs acknowledges support by the DFG Germany's Excellence Strategy—EXC-2123 'QuantumFrontiers'—390837967. M Fucilla, M M A Mohammed, and A Papa acknowledge support from the INFN/QFT@COLLIDERS project. A Garcia acknowledges support from the European Union's H2020-MSCA Grant Agreement 101025085. C A García Canal and S J Sciutto acknowledge support from CONICET and ANPCyT M V Garzelli acknowledges support the from German BMBF Contract 05H21GUCCA. V P Goncalves was partially financed by the Brazilian funding agencies CNPq, CAPES, FAPERGS and INCT-FNA (Process Number 464898/2014-5). S Goswami acknowledges the J C Bose Fellowship (JCB/2020/000011) of Science and Engineering Research Board of Department of Science and Technology, Government of India. The work of M Guzzi is supported by US NSF Grant PHY-2112025. L Harland-Lang thanks the Science and Technology Facilities Council (STFC) for support via Grant Award ST/L000377/1. The work of S P Harris is supported by the US DOE Grant DE-FG02-00ER41132 as well as the US NSF Grant PHY-1430152 (JINA Center for the Evolution of the Elements). J C Helo acknowledge support from Grant ANID FONDECYT-Chile 1201673 and ANID—Millennium Science Initiative Program ICN2019-044. The work of M Hirsch is supported by the Spanish Grants PID2020-113775GB-I00 (AEI/10.13039/501100011033) and PROMETEO/2018/165 (Generalitat Valenciana). The work of A Hryczuk and M Laletin is supported by the National Science Centre, Poland, research Grant 2018/31/D/ST2/00813. The research activities of F Huang are supported by the International Postdoctoral Exchange Fellowship Program and in part by US NSF Grant PHY-1915005. A Ismail is supported by NSERC (Reference Number 557763) and by US NSF Grant PHY-2014071. Y S Jeong acknowledges support from the National Research Foundation of Korea (NRF) grant funded by the Korea government through Ministry of Science and ICT Grant 2021R1A2C1009296. K Jodlowski and L Roszkowski are supported by the National Science Centre, Poland, research Grant 2015/18/A/ST2/00748. S R Klein is supported in part by the US NSF Grant PHY-1307472 and the US DOE Contract DE-AC-76SF00098. F Kling and P Quílez are supported by the DFG under Germany's Excellence Strategy—EXC 2121 Quantum Universe—390833306. P Ko is supported in part by KIAS Individual Grant PG021403 and by National Research Foundation of Korea (NRF) Grant NRF-2019R1A2C3005009. S Kulkarni is supported by the Austrian Science Fund Elise-Richter Grant V592-N27. The work of J Kumar is supported in part by US DOE Grant DE-SC0010504. J-L Kuo is supported by US NSF Theoretical Physics Program, Grant PHY-1915005. The work of C Le Roux and K Zapp is part of a project that has received funding from the ERC under the European Union's Horizon 2020 Research and Innovation Programme (Grant Agreement 803183, collectiveQCD). The work of H-S Lee was supported in part by the National Research Foundation of Korea (NRF-2021R1A2C2009718). S J Lee was supported by the Samsung Science and Technology Foundation. Ji Li is supported by the National Natural Science Foundation of China Grant 11905149. K-F Lyu and Z Liu are supported in part by the US DOE Grant DE-SC0022345. The work of R Maciula and A Szczurek was partially supported by the Polish National Science Centre under Grant 2018/31/B/ST2/03537. R Mammen Abraham and A Ismail acknowledge support from the US DOE Grant DE-SC0016013. M R Masouminia is supported by the UK Science and Technology Facilities Council (Grant ST/P001246/1). The work of J McFayden was supported by the Royal Society Fellowship Grant URF R1 201519. The work of O Mikulenko is supported by the NWO Physics Vrij Programme 'The Hidden Universe of Weakly Inter-acting Particles' with Project Number 680.92.18.03 (NWO Vrije Programma), which is (partly) financed by the Dutch Research Council (NWO). P Nadolsky and F Olness acknowledge support through US DOE Grant DE-SC0010129. E R Nocera thanks the STFC for support by the Grant Awards ST/P000630/1and ST/T000600/1. The work of N Okada is supported by the US DOE Grant DE-SC0012447. V Pandey acknowledges the support from US DOE Grant DE-SC0009824. The work of D Raut is supported by the US DOE Grant DE-SC0013880. P Reimitz acknowledges financial support from FAPESP Contract 2020/10004-7. M H Reno is supported in part by US DOE Grant DE-SC-0010113. The work of J Rojo is partly supported by the Dutch Research Council (NWO). L Roszkowski and S Trojanowski are supported by the grant 'AstroCeNT: Particle Astrophysics Science and Technology Centre' carried out within the International Research Agendas programme of the Foundation for Polish Science financed by the European Union under the European Regional Development Fund. S Trojanowski is also supported in part by the Polish Ministry of Science and Higher Education through its scholarship for young and outstanding scientists (Decision No. 1190/E-78/STYP/14/2019). S Trojanowski is also supported in part from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No. 952480 (DarkWave 24 project). I Sarcevic is supported by US DOE Grant DOE DE-SC-0009913. The work of L Shchutska is supported by the ERC under the European Union's Horizon 2020 Research and Innovation Programme (GA 758316). The work of T Shimomura is supported by JSPS KAKENHI Grants JP18H01210, JP18K03651, and MEXT KAKENHI Grant JP18H05543. The work of K Sinha is supported in part by US DOE Grant DE-SC0009956. The work of T Sjöstrand is supported by the Swedish Research Council, Contract 2016-05996. J T Sobczyk acknowledges support from NCN Grant UMO-2021/41/B/ST2/02778. D Soldin acknowledges support from the US NSF Grant PHY-1913607. H Song is supported by the International Postdoctoral Exchange Fellowship Program. Y Soreq is supported by grants from the NSF-BSF, BSF, the ISF and by the Azrieli foundation. A Stasto acknowledges support from US DOE Grant DE-SC-0002145. S Su is supported by the US DOE Grant DE-FG02-13ER41976/DE-SC0009913. W Su is supported by a KIAS Individual Grant (PG084201) at Korea Institute for Advanced Study. Y Takubo is supported by JP20K04004. M Taoso acknowledges support from the INFN Grant 'LINDARK', the research grant 'The Dark Universe: A Synergic Multimessenger Approach 2017X7X85' funded by MIUR, and the project 'Theoretical Astroparticle Physics (TAsP)' funded by the INFN. The research activities of B Thomas are supported in part by US NSF Grant PHY-2014104. The work of Y-D Tsai is supported in part by US NSF Grant PHY-1915005. The work of A Sabio Vera has been supported by the Spanish Research Agency (Agencia Estatal de Investigación) through the Grant IFT Centro de Excelencia Severo Ochoa SEV-2016-0597, by the Spanish Government Grant FPA2016-78022-P and from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement 824093. The work of Yongchao Zhang is supported by the National Natural Science Foundation of China Grant 12175039, the 2021 Jiangsu Shuangchuang (Mass Innovation and Entrepreneurship) Talent Program JSSCBS20210144, and the 'Fundamental Research Funds for the Central Universities'. Yue Zhang is supported by the Arthur B McDonald Canadian Astroparticle Physics Research Institute. R Zukanovich Funchal is partially supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) and Conselho Nacional de Ciência e Tecnologia (CNPq). The opinions and conclusions expressed herein are those of the authors and do not represent any funding agencies., High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential., German Research Foundation (DFG) SFB 876 SFB 1491, National Science Foundation (NSF) PHY2112527, Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research (KAKENHI) JP18H01210 JSPS KAKENHI JP20K23373 JP19H01909 JSPS KAKENHI JP19J13812 JP21K20365 JSPS KAKENHI JP18K03651, European Research Council (ERC) 101002690, National Research Foundation of Korea NRF-2020R1I1A3072747, Patrimonio Autónomo-Fondo Nacional de Financiamiento para la Ciencia Tecnología y la Innovación Francisco José de Caldas (MinCiencias-Colombia) 80740-465-2020, European Commission Joint Research Centre 860881-HIDDeN European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant 754446, United States Department of Energy (DOE) DE-SC0007914, Fermi National Accelerator Laboratory (Fermilab), a US DOE, Office of Science, HEP User Facility, Fermi Research Alliance, LLC (FRA) DE-AC02-07CH11359, German Research Foundation (DFG) HA 8555/1-1, DFG Collaborative Research Centre 'Neutrinos and Dark Matter in Astro-and Particle Physics' SFB 1258, Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) 2015/25884-4 2019/15149-6, United States Department of Energy (DOE) DE-SC0009920, Heising-Simons Foundation 2022-3319 2019-1179 2020-1840, ERC under the European Union's Horizon 2020 Research and Innovation Programme 694896 803183, UGR Research and Knowledge Transfer Found-Athenea3i, Ministry of Science and Innovation, Spain (MICINN) Spanish Government, SRA Grant PID2019-106087GB-C22, Junta de Andalucía A-FQM-472-UGR20, Fundacao para a Ciencia e a Tecnologia (FCT) CERN/FIS-PAR/0024/2019 03216/2017, United States Department of Energy (DOE) DE-SC0011702 DE-SC0017987 DE-FG02-13ER41976/DE-SC0009913 DE-SC0012704 DE-SC0010813 DE-AC02-76SF00515 DE-FG02-00ER41132 DE-AC-76SF00098 DE-SC0010504 DE-SC0022345 DE-SC0010129, US NSF through its employee IR/D program, National Key Research and Development Program of China 2020YFC2201501, National Natural Science Foundation of China (NSFC) 12022514 11875003 12047503, CAS Project for Young Scientists in Basic Research YSBR-006, Key Research Program of the CAS XDPB15, National Research Foundation of Korea (NRF)'s Grants 6N021413, Saramadan Contract ISEF/M/400279, National Science Foundation (NSF) PHY-1915005 PHY-2111427 PHY1430152 PHY-2014071 PHY-1307472 PHY-2014104, Simons Investigator Award 376204, Simons Foundation 623683, National Science Foundation (NSF) DGE-1839285, FAPESP Contract 2020/00174-2, UKRI Future Leaders Fellowship DARKMAP, Natural Sciences and Engineering Research Council of Canada (NSERC), German Research Foundation (DFG) EXC-2123 390837967, INFN/QFT@COLLIDERS project, European Union's H2020-MSCA Grant Agreement 101025085, Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), ANPCyT, Federal Ministry of Education & Research (BMBF) 05H21GUCCA, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ), Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES), Fundacao de Amparo a Ciencia e Tecnologia do Estado do Rio Grande do Sul (FAPERGS), INCT-FNA 464898/2014-5, J C Bose Fellowship of Science and Engineering Research Board of Department of Science and Technology, Government of India JCB/2020/000011, National Science Foundation (NSF) PHY-2112025, UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) Science and Technology Development Fund (STDF) ST/L000377/1, Grant ANID FONDECYT-Chile 1201673, ANID-Millennium Science Initiative Program ICN2019-044, Spanish Grant (AEI) PID2020-113775GBI00, Center for Forestry Research & Experimentation (CIEF) PROMETEO/2018/165, National Science Centre, Poland 2018/31/D/ST2/00813, International Postdoctoral Exchange Fellowship Program, KIAS Individual Grant PG021403, National Research Foundation of Korea NRF-2019R1A2C3005009, Austrian Science Fund Elise-Richter Grant V592-N27, US NSF Theoretical Physics Program PHY-1915005, Samsung, National Natural Science Foundation of China (NSFC) 11905149, Polish National Science Centre 2018/31/B/ST2/03537, UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) ST/P001246/1, Royal Society of London URF R1 201519, Netherlands Organization for Scientific Research (NWO) 680.92.18.03 Physics Vrij Programme .The Hidden Universe of Weakly Inter-acting Particles' - Dutch Research Council (NWO), UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) ST/T000600/1 ST/P000630/1, Netherlands Organization for Scientific Research (NWO), European Union under the European Regional Development Fund, Polish Ministry of Science and Higher Education through its scholarship for young and outstanding scientists 1190/E-78/STYP/14/2019, European Commission 952480, ERC under the European Union 758316, Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research (KAKENHI) JP18H05543 MEXT KAKENHI, Swedish Research Council 2016-05996, NCN UMO-2021/41/B/ST2/02778, NSF-BSF, US-Israel Binational Science Foundation, Israel Science Foundation, Azrieli foundation, KIAS Individual Grant at Korea Institute for Advanced Study PG084201, Istituto Nazionale di Fisica Nucleare (INFN), Ministry of Education, Universities and Research (MIUR) 2017X7X85', Spanish Government SEV-2016-0597 Spanish Research Agency (Agencia Estatal de Investigacion) through the Grant IFT Centro de Excelencia Severo Ochoa FPA2016-78022-P, European Union's Horizon 2020 Research and Innovation Programme 824093, National Natural Science Foundation of China (NSFC) 12175039, 2021 Jiangsu Shuangchuang (Mass Innovation and Entrepreneurship) Talent Program JSSCBS20210144, Fundamental Research Funds for the Central Universities, Arthur B McDonald Canadian Astroparticle Physics Research Institute, Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP), United States Department of Energy (DOE) DE-SC0012447 DE-SC0009824 DE-SC0013880 :The US DOE DE-SC-0010113 DOE DE-SC-0009913 US DOE DE-SC0009956 DE-FG02-13ER41976/DESC0009913 US DOE JP20K04004

In the presence of transition magnetic moments between active and sterile neutrinos, the search for a Primakoff upscattering process at coherent elastic neutrino-nucleus scattering (CE$ν$NS) experiments can provide stringent constraints on the neutrino magnetic moment. We show that a radiative upscattering process with an emitted photon in the final state can induce a novel coincidence signal at CE$ν$NS experiments that can also probe neutrino transition magnetic moments beyond existing limits. Furthermore, the differential distributions for such a radiative mode can also potentially be sensitive to the Dirac vs. Majorana nature of the sterile state mediating the process. This can provide valuable insights into the nature and mass generation mechanism of the light active neutrinos., 38 pages, 9 figures; expanded discussion of constraints, matches published version

Bayesian parameter inference techniques require a choice of prior distribution which can strongly impact the statistical conclusions drawn. We discuss the construction of least-informative priors for neutrinoless double beta decay searches. Such priors attempt to be objective by maximizing the information gain from an experimental setup. In a parametrization using the lightest neutrino mass $m_l$ and an effective Majorana phase parameter $��$, we construct such a prior using two different approaches and compare them with the standard flat and logarithmic priors in $m_l$., 19 pages, 6 figures, matches published version

Neutrinoless double beta decay ($0������$) is a crucial test for lepton number violation. Observation of this process would have fundamental implications for neutrino physics, theories beyond the Standard Model and cosmology. Focussing on so called short-range operators of $0������$ and their potential interplay with the standard light Majorana neutrino exchange, we present the first complete calculation of the relevant nuclear matrix elements, performed within the interacting boson model (IBM-2). Furthermore, we calculate the relevant phase space factors using exact Dirac electron wavefunctions, taking into account the finite nuclear size and screening by the electron cloud. The obtained numerical results are presented together with up-to-date limits on the standard mass mechanism and effective $0������$ short-range operators in the IBM-2 framework. Finally, we interpret the limits in the particle physics scenarios incorporating heavy sterile neutrinos, Left-Right symmetry and R-parity violating supersymmetry., 54 pages, 10 figures, 14 tables, including appendix, v2 matches published version

We present a novel mode of neutrinoless double beta decay with emission of a light Majoron-like scalar particle phi. We assume it couples via an effective seven-dimensional operator with a (V+A) lepton current and (V+-A) quark currents leading to a long-range contribution that is unsuppressed by the light neutrino mass. We calculate the total double beta decay rate and determine the fully differential shape for this mode. We find that future double beta decay searches are sensitive to scales of the order Lambda_NP ~ 1 TeV for the effective operator and a light scalar m_phi < 0.2 MeV, based on ordinary double beta decay Majoron searches. The angular and energy distributions can deviate considerably from that of two-neutrino double beta decay, which is the main background. We point out possible ultraviolet completions where such an effective operator can emerge., 25 pages, 4 figures, including appendices, matches published version

Models of neutrino mass generation provide well motivated scenarios of Beyond-the-Standard-Model physics. The synergy between low energy and high energy LHC searches facilitates an effective approach to rule out, constrain or ideally pinpoint such models. In this proceedings report, we provide a brief overview of scenarios where searches at the LHC can help determine the mechanism of light neutrino masses and potentially falsify baryogenesis mechanisms., Comment: Talk presented at CIPANP2015. 9 pages, 3 figures

In this review article, we highlight the impact of models incorporating flavour symmetries on charged lepton flavour violating (LFV) processes. Flavour symmetries provide a natural approach to explain the peculiar mass hierarchies and mixing patterns of the Standard Model fermions. New sources of LFV are generally present in new physics beyond the Standard Model, and flavour symmetries can make distinctive predictions for LFV observables. Their discovery can provide crucial information to distinguish flavour symmetries and new physics scenarios in general. Because of their high sensitivity, we will focus on searches for low-energy LFV processes such as mu --> e gamma or mu-e conversion in nuclei but we will also highlight the potential impact of LFV processes at the LHC. If new physics occurs at a scale accessible by the LHC, the flavour operators they induce could potentially be probed in high detail., Contribution to special issue on 'Discrete Symmetries' to appear in 'Fortschritte der Physik', 26 pages, 12 figures, added references

We investigate nuclear mu-e conversion in the framework of an effective Lagrangian arising from the inverse seesaw model of neutrino masses. We consider lepton flavour violation interactions that arise from short range (non-photonic) as well as long range (photonic) contributions. Upper bounds for the LFV parameters characterizing mu-e conversion are derived in the inverse seesaw model Lagrangian using the available limits on the mu-e conversion branching ratio, as well as the expected sensitivities of upcoming experiments. We comment on the relative importance of these two types of contributions and their relationship with the measured solar neutrino mixing angle theta_12 and the dependence on theta_13. Finally we show how the LFV mu-e conversion and the mu -> e gamma rates are strongly correlated in this model.

This is the Snowmass2021 Energy Frontier (EF) Beyond the Standard Model (BSM) report. It combines the EF topical group reports of EF08 (Model-specific explorations), EF09 (More general explorations), and EF10 (Dark Matter at Colliders). The report includes a general introduction to BSM motivations and the comparative prospects for proposed future experiments for a broad range of potential BSM models and signatures, including compositeness, SUSY, leptoquarks, more general new bosons and fermions, long-lived particles, dark matter, charged-lepton flavor violation, and anomaly detection., Comment: 108 pages + 38 pages references and appendix, 37 figures, Report of the Topical Group on Beyond the Standard Model Physics at Energy Frontier for Snowmass 2021. The first nine authors are the Conveners, with Contributions from the other authors