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A bstract Following our earlier work we establish kinematic endpoint relations for baryon decays using the Wigner-Eckart theorem and apply them to 1 2 → 1 2 and 1 2 → 3 2 baryon transitions. We provide angular distributions at the kinematic endpoint which hold for the generic d = 6 model-independent effective Hamiltonian and comment on the behaviour in the vicinity of the endpoint. Moreover, we verify the endpoint relations, using an explicit form factor parametrisation, and clarify constraints on helicity-based form factors to evidence endpoint relations. Our results provide guidance for phenomenological parameterisations, consistency checks for theory computations and experiment. Results are applicable to ongoing and future new physics searches at LHCb, BES III and Belle II with rare semileptonic-, dineutrino-and charged-modes, which include Λ b → Λ (*) ℓℓ, Λ b → Λ (*) νν , Ω b → Ω ℓℓ , Λ c → pℓℓ , Σ → pℓℓ and Λ b → Λ c ∗ ℓν .

A bstract We present a systematic global analysis of dineutrino modes b → qν ν ¯ , q = d, s , and charged dilepton b → qℓ + ℓ − transitions. We derive improved or even entirely new limits on dineutrino branching ratios including decays B 0 → ( K 0 , X s ) ν ν ¯ , B s → ϕν ν ¯ and B 0 → ( π 0 , ρ 0 ) ν ν ¯ from dineutrino modes which presently are best constrained: B + → ( K + , π + , ρ + ) ν ν ¯ and B 0 → K *0 ν ν ¯ . Using SMEFT we obtain new flavor constraints from the dineutrino modes, which are stronger than the corresponding ones from charged dilepton rare b -decay or Drell-Yan data, for eτ and ττ final states, as well as for μτ ones in b → s processes. The method also allows to put novel constraints on semileptonic four-fermion operators with top quarks. Implications for ditau modes b → sτ + τ − and b → dτ + τ − are worked out. Even stronger constraints are obtained in simplified BSM frameworks such as leptoquarks and Z ′-models. Furthermore, the interplay between dineutrinos and charged dileptons allows for concrete, novel tests of lepton universality in rare B -decays. Performing a global fit to b → sμ + μ − , sγ transitions we find that lepton universality predicts the ratio of the B 0 → K *0 ν ν ¯ to B 0 → K 0 ν ν ¯ ( B + → K + ν ν ¯ ) branching fractions to be within 1.7 to 2.6 (1.6 to 2.4) at 1 σ , a region that includes the standard model, and that can be narrowed with improved charged dilepton data. There is sizable room outside this region where universality is broken and that can be probed with the Belle II experiment. Using results of a fit to B 0 → μ + μ − , B s 0 → K ¯ *0 μ + μ − and B + → π + μ + μ − data we obtain an analogous relation for | ∆ b| = | ∆ d| = 1 transitions: if lepton universality holds the ratio of the B 0 → ρ 0 ν ν ¯ to B 0 → π 0 ν ν ¯ ( B + → π + ν ν ¯ ) branching fractions is within 2.5 to 5.7 (1.2 to 2.6) at 1 σ . Putting upper limits on B ( B s → ν ν ¯ ) at the level of 10 − 5 and B ( B 0 → ν ν ¯ ) below 10 − 6 would allow to control backgrounds from (pseudo-)scalar operators such as those induced by light right-handed neutrinos.

A bstract We perform global fits within Standard Model Effective Field Theory (SMEFT) combining top-quark pair production processes and decay with b → s flavor changing neutral current transitions and Z → b b ¯ in three stages: using existing data from the LHC and B -factories, using projections for the HL-LHC and Belle II, and studying the additional new physics impact from a future lepton collider. The latter is ideally suited to directly probe ℓ + ℓ − → t t ¯ transitions. We observe powerful synergies in combining both top and beauty observables as flat directions are removed and more operators can be probed. We find that a future lepton collider significantly enhances this interplay and qualitatively improves global SMEFT fits.

A bstract We analyze rare charm baryon decays within the standard model and beyond. We identify all null test observables in unpolarized Λ c → pℓ + ℓ − , ℓ = e, μ decays, and study the new physics sensitivities. We find that the longitudinal dilepton polarization fraction F L is sensitive to electromagnetic dipole couplings C 7 ′ , and to the right-handed 4-fermion vector coupling C 9 ′ . The forward-backward asymmetry, A FB , due to the GIM-suppression a standard model null test already, probes the left-handed axialvector 4-fermion coupling C 10 ; its CP–asymmetry, A FB CP probes CP-violating phases in C 10 . Physics beyond the standard model can induce branching ratios of dineutrino modes Λ c → pν ν ¯ up to a few times 10 − 5 , and one order of magnitude smaller if lepton flavor universality is assumed, while standard model rates are negligible. Charged lepton flavor violation allows for striking signals into e ± μ ∓ final states, up to 10 − 6 branching ratios model-independently, and up to order 10 − 8 in leptoquark models. Related three-body baryon decays Ξ c → Σ ℓℓ , Ξ c → Λ ℓℓ and Ω c → Ξ ℓℓ offer similar opportunities to test the standard model with | ∆ c| = | ∆ u| = 1 transitions.

A bstract Evidence for electron-muon universality violation that has been revealed in b → sℓℓ transitions in the observables R KK ∗ by the LHCb Collaboration can be explained with spin-1 leptoquarks in SU(2) L singlet V 1 or triplet V 3 representations in the O (1 − 10) TeV range. We explore the sensitivity of the high luminosity LHC (HL-LHC) and future proton-proton colliders to V 1 and V 3 in the parameter space connected to R KK ∗ -data. We consider pair production and single production in association with muons in different flavor benchmarks. Reinterpreting a recent ATLAS search for scalar leptoquarks decaying to bμ and jμ , we extract improved limits for the leptoquark masses: for gauge boson-type leptoquarks ( κ = 1) we obtain M V 1 > 1 . 9 TeV, M V 1 > 1 . 9 TeV, and M V 1 > 1 . 7 TeV for leptoquarks decaying predominantly according to hierarchical, flipped and democratic quark flavor structure, respectively. Future sensitivity projections based on extrapolations of existing ATLAS and CMS searches are worked out. We find that for κ = 1 the mass reach for pair (single) production of V 1 can be up to 3 TeV (2.1 TeV) at the HL-LHC and up to 15 TeV (19.9 TeV) at the FCC-hh with s = 100 TeV and 20 ab − 1 . The mass limits and reach for the triplet V 3 are similar or higher, depending on flavor. While there is the exciting possibility that leptoquarks addressing the R KK ∗ -anomalies are observed at the LHC, to fully cover the parameter space pp -collisions beyond the LHC-energies are needed.

A bstract We study the production of dineutrinos in proton-proton collisions, with large missing transverse energy and an energetic jet as the experimental signature. Recasting a search from the ATLAS collaboration we work out constraints on semileptonic four-fermion operators, gluon and electroweak dipole operators and Z -penguins in the SMEFT. All but the Z -penguin operators experience energy-enhancement. Constraints on gluon dipole operators are the strongest, probing new physics up to 14 TeV, and improve over existing ones from collider studies. Limits on FCNC four-fermion operators are competitive with Drell-Yan production of dileptons, and improve on those for tau final states. For left-handed |∆ s | = |∆ d | = 1 and right-handed |∆ c | = |∆ u | = 1 transitions these are the best available limits, also considering rare kaon and charm decays. We estimate improvements for the 3000 fb −1 High Luminosity Large Hadron Collider.

A bstract We perform a global analysis of Beauty, Top, Z and Drell-Yan measurements in the framework of the Standard Model effective theory (SMEFT). We work within the minimal flavor violation (MFV) hypothesis, which relates different sectors and generations beyond the SU(2) L -link between left-handed top and beauty quarks. We find that the constraints on the SMEFT Wilson coefficients from the combined analysis are stronger than the constraints from a fit to the individual sectors, highlighting synergies in the global approach. We also show that constraints within MFV are strengthened compared to single-generation fits. The strongest bounds are obtained for the semileptonic four-fermion triplet operator C lq 3 , probing scales as high as 18 TeV, followed by the gluon dipole operator C uG with 7 TeV, and other four-fermion and penguin operators in the multi-TeV range. Operators with left-handed quark bilinears receive order one contributions from higher orders in the MFV expansion induced by the top Yukawa coupling as a result of the FCNC b → sμμ anomalies combined with the other sectors. We predict the 68% credible intervals of the dineutrino branching ratios within MFV as 4.25 ⋅ 10 − 6 ≤ B B 0 → K ∗ 0 ν ν ¯ ≤ 11.13 ⋅ 10 − 6 and 2.26 ⋅ 10 − 6 ≤ B B + → K + ν ν ¯ ≤ 5.78 ⋅ 10 − 6 , which include the respective Standard Model predictions, and are in reach of the Belle II experiment. We show how future measurements of the dineutrino branching ratios can provide insights into the structure of new physics in the global fit.

SU(2)L-invariance links charged dilepton and dineutrino couplings. Phenomenological implications are worked out for flavor changing neutral currents involving strange, charm, beauty and top quark transitions in a model-independent way. We put forward novel tests of lepton universality and lepton flavor conservation in |Δc|=|Δu|=1 and |Δb|=|Δq|=1, q=d,s, transitions suitable for the experiments Belle II and BES III. Single top production plus dileptons uniquely probes semileptonic four-fermion |Δt|=|Δq′|=1, q′=u,c, couplings and further study at the LHC is encouraged. Tests with single top production associated with dileptons and missing energy are suitable for study at future e+e- or muon colliders.

U(1)′ extensions of the standard model with generation-dependent couplings to quarks and leptons are investigated as an explanation of anomalies in rare B-decays, with an emphasis on stability and predictivity up to the Planck scale. To these ends, we introduce three generations of vector-like standard model singlet fermions, an enlarged, flavorful scalar sector, and, possibly, right-handed neutrinos, all suitably charged under the U(1)′ gauge interaction. We identify several gauge-anomaly free benchmarks consistent with Bs-mixing constraints, with hints for electron-muon universality violation, and the global b→s fit. We further investigate the complete two-loop running of gauge, Yukawa and quartic couplings up to the Planck scale to constrain low-energy parameters and enhance the predictive power. A characteristic of models is that the Z′ with TeV-ish mass predominantly decays to invisibles, i.e. new fermions or neutrinos. Z′-production can be studied at a future muon collider. While benchmarks feature predominantly left-handed couplings C9μ and C10μ, right-handed ones can be accommodated as well.

| Δ c | = | Δ u | = 1 processes are unique probes of flavor physics in the up-sector within and beyond the Standard Model (SM). SM tests with rare semileptonic charm meson decays are based on an approximate CP–symmetry, a superior GIM–mechanism, angular distributions, lepton-universality and lepton flavor conservation. We analyze the complete set of null test observables in D → π ℓ ℓ ( ′ ) and D s → K ℓ ℓ ( ′ ) decays, ℓ ( ′ ) = e , μ , and find large room for new physics safely above the SM contribution. We identify signatures of supersymmetry, leptoquarks and anomaly-free U ( 1 ) ′ –models with generation-dependent charges, for which we provide explicit examples. Z ′ –effects in c → u ℓ ℓ ( ′ ) transitions can be sizable if both left-handed and right-handed couplings to quarks are present.