We revisit the physics of neutrino magnetic moments, focusing in particular on the case where the right-handed, or sterile, neutrinos are heavier (up to several MeV) than the left-handed Standard Model neutrinos. The discussion is centered around the idea of detecting an upscattering event mediated by a transition magnetic moment in a neutrino or dark matter experiment. Considering neutrinos from all known sources, as well as including all available data from XENON1T and Borexino, we derive the strongest up-to-date exclusion limits on the active-to-sterile neutrino transition magnetic moment. We then study complementary constraints from astrophysics and cosmology, performing, in particular, a thorough analysis of BBN . We find that these data sets scrutinize most of the relevant parameter space. Explaining the XENON1T excess with transition magnetic moments is marginally possible if very conservative assumptions are adopted regarding the supernova 1987 A and CMB constraints. Finally, we discuss model-building challenges that arise in scenarios that feature large magnetic moments while keeping neutrino masses well below 1 eV. We present a successful ultraviolet-complete model of this type based on TeV-scale leptoquarks, establishing links with muon magnetic moment, B physics anomalies, and collider searches at the LHC.

We report on the status of efforts to improve the reinterpretation of searches and measurements at the LHC in terms of models for new physics, in the context of the LHC Reinterpretation Forum. We detail current experimental offerings in direct searches for new particles, measurements, technical implementations and Open Data, and provide a set of recommendations for further improving the presentation of LHC results in order to better enable reinterpretation in the future. We also provide a brief description of existing software reinterpretation frameworks and recent global analyses of new physics that make use of the current data.

The mass hierarchy among the three generations of quarks and charged leptons is one of the greatest mysteries in particle physics. In various flavor models, the origin of this phenomenon is attributed to a series of hierarchical spontaneous symmetry breakings, most of which are beyond the reach of particle colliders. We point out that the observation of a multipeaked stochastic gravitational wave signal from a series of cosmological phase transitions could well be a unique probe of the mechanism behind flavor hierarchies. To illustrate this point, we show how near future ground- and space-based gravitational wave observatories could detect up to three peaks in the recently proposed PS^{3} model.

We propose a procedure to cross-validate Monte Carlo implementations of the standard model effective field theory. It is based on the numerical comparison of squared amplitudes computed at specific phase-space and parameter points in pairs of implementations. Interactions are fully linearised in the effective field theory expansion. The squares of linear effective field theory amplitudes and their interference with standard-model contributions are compared separately. Such pairwise comparisons are primarily performed at tree level and a possible extension to the one-loop level is also briefly considered. We list the current standard model effective field theory implementations and the comparisons performed to date.

: We analyze the bounds on the Higgs pseudo-observables following from electroweak constraints, under the assumption that the Higgs particle is the massive excitation of an SU (2) L doublet. Using such bounds, detailed predictions for h → 4 ℓ decay rates, dilepton spectra, and lepton-universality ratios are presented. Abstract We analyze the bounds on the Higgs pseudo-ob-servables following from electroweak constraints, under the assumption that the Higgs particle is the massive excitation of an SU ( 2 ) L doublet. Using such bounds, detailed predictions for h → 4 (cid:2) decay rates, dilepton spectra, and lepton-universality ratios are presented.

We propose a procedure to cross-validate Monte Carlo implementations of the standard model effective field theory. It is based on the numerical comparison of squared amplitudes computed at specific phase-space and parameter points in pairs of implementations. Interactions are fully linearised in the effective field theory expansion. The squares of linear effective field theory amplitudes and their interference with standard-model contributions are compared separately. Such pairwise comparisons are primarily performed at tree level and a possible extension to the one-loop level is also briefly considered. We list the current standard model effective field theory implementations and the comparisons performed to date. 1 ar X iv :1 90 6. 12 31 0v 1 [ he pph ] 2 8 Ju n 20 19

This is the third out of five chapters of the final report [1] of the Workshop on Physics at HL-LHC, and perspectives on HE-LHC [2]. It is devoted to the study of the potential, in the search for Beyond the Standard Model (BSM) physics, of the High Luminosity (HL) phase of the LHC, defined as $3$ ab$^{-1}$ of data taken at a centre-of-mass energy of 14 TeV, and of a possible future upgrade, the High Energy (HE) LHC, defined as $15$ ab$^{-1}$ of data at a centre-of-mass energy of 27 TeV. We consider a large variety of new physics models, both in a simplified model fashion and in a more model-dependent one. A long list of contributions from the theory and experimental (ATLAS, CMS, LHCb) communities have been collected and merged together to give a complete, wide, and consistent view of future prospects for BSM physics at the considered colliders. On top of the usual standard candles, such as supersymmetric simplified models and resonances, considered for the evaluation of future collider potentials, this report contains results on dark matter and dark sectors, long lived particles, leptoquarks, sterile neutrinos, axion-like particles, heavy scalars, vector-like quarks, and more. Particular attention is placed, especially in the study of the HL-LHC prospects, to the detector upgrades, the assessment of the future systematic uncertainties, and new experimental techniques. The general conclusion is that the HL-LHC, on top of allowing to extend the present LHC mass and coupling reach by $20-50\%$ on most new physics scenarios, will also be able to constrain, and potentially discover, new physics that is presently unconstrained. Moreover, compared to the HL-LHC, the reach in most observables will, generally more than double at the HE-LHC, which may represent a good candidate future facility for a final test of TeV-scale new physics.

Author(s): Blas, J de; Franceschini, R; Riva, F; Roloff, P; Schnoor, U; Spannowsky, M; Wells, JD; Wulzer, A; Zupan, J; Alipour-Fard, S; Altmannshofer, W; Azatov, A; Azevedo, D; Baglio, J; Bauer, M; Bishara, F; Blaising, J-J; Brass, S; Buttazzo, D; Chacko, Z; Craig, N; Cui, Y; Dercks, D; Dev, PS Bhupal; Luzio, L Di; Vita, S Di; Durieux, G; Fan, J; Ferreira, P; Frugiuele, C; Fuchs, E; Garcia, I; Ghezzi, M; Greljo, A; Grober, R; Grojean, C; Gu, J; Hunter, R; Joglekar, A; Kalinowski, J; Kilian, W; Kilic, C; Kotlarski, W; Kucharczyk, M; Leogrande, E; Linssen, L; Liu, D; Liu, Z; Lombardo, DM; Low, I; Matsedonskyi, O; Marzocca, D; Mimasu, K; Mitov, A; Mitra, M; Mohapatra, RN; Moortgat-Pick, G; Muhlleitner, M; Najjari, S; Nardecchia, M; Neubert, M; No, JM; Panico, G; Panizzi, L; Paul, A; Perello, M; Perez, G; Plascencia, AD; Pruna, GM; Redigolo, D; Reece, M; Reuter, J; Riembau, M; Robens, T; Robson, A; Rolbiecki, K; Sailer, A; Sakurai, K; Sala, F; Santos, R; Schlaffer, M; Shim, SY; Shuve, B; Simoniello, R; Sokolowska, D | Abstract: The Compact Linear Collider (CLIC) is a mature option for the future of high energy physics. It combines the benefits of the clean environment of $e^+e^-$ colliders with operation at high centre-of-mass energies, allowing to probe scales beyond the reach of the Large Hadron Collider (LHC) for many scenarios of new physics. This places the CLIC project at a privileged spot in between the precision and energy frontiers, with capabilities that will significantly extend knowledge on both fronts at the end of the LHC era. In this report we review and revisit the potential of CLIC to search, directly and indirectly, for physics beyond the Standard Model.

We investigate the crossing-symmetry relation between b→cτ^{-}ν[over ¯] decay and bc[over ¯]→τ^{-}ν[over ¯] scattering to derive direct correlations of new physics in semitauonic B-meson decays and the mono-tau signature at the LHC (pp→τ_{h}X+MET). Using an exhaustive set of effective operators and heavy mediators we find that the current ATLAS and CMS data constrain scenarios addressing anomalies in B decays. Pure tensor solutions, completed by leptoquark, and right-handed solutions, completed by W_{R}^{'} or leptoquark, are challenged by our analysis. Furthermore, the sensitivity that will be achieved in the high-luminosity phase of the LHC will probe all the possible scenarios that explain the anomalies. Finally, we note that the LHC is also competitive in the b→u transitions and bounds in some cases are currently better than those from B decays.