Constraints on the two-pion contribution to hadronic vacuum polarization

With the long-standing tension between experiment and Standard-Model (SM) prediction in the anomalous magnetic moment of the muon aμ recently reaffirmed by the Fermilab experiment, the crucial question becomes which other observables could be sensitive to the underlying physics beyond the SM to which aμ may be pointing. While from the effective field theory (EFT) point of view no direct correlations exist, this changes in specific new physics models. In particular, in the case of explanations involving heavy new particles above the electroweak (EW) scale with chiral enhancement, which are preferred to evade exclusion limits from direct searches, correlations with other observables sensitive to EW symmetry breaking are expected. Such scenarios can be classified according to the SU(2)L representations and the hypercharges of the new particles. We match the resulting class of models with heavy new scalars and fermions onto SMEFT and study the resulting correlations with h → μμ and Z → μμ decays, where, via SU(2)L symmetry, the latter process is related to Z → νν and modified W-μ-ν couplings.

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“…Some recent developments include refs [34][35][36][37][38][39][40]. for hadronic vacuum polarization and refs [41][42][43][44][45][46][47][48].…”

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confidence: 99%

Consequences of chirally enhanced explanations of (g − 2)μ for h → μμ and Z → μμ

Crivellin

Hoferichter

2021

J. High Energ. Phys.

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“…The advantage of the standard approach is that the result directly applies to an arbitrary pion vector form factor, while collecting the residues in the k 0 integration assumes the form dictated by vector meson dominance. For our application this approximation is completely sufficient, but could be improved by using a dispersive representation of F V π (k 2 ) [119,120] and treating the Cauchy kernel along the same lines.…”

Section: Jhep05(2021)289mentioning

confidence: 99%

Determining the leading-order contact term in neutrinoless double β decay

Cirigliano

Dekens

Vries

et al. 2021

J. High Energ. Phys.

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We present a method to determine the leading-order (LO) contact term contributing to the nn → ppe−e− amplitude through the exchange of light Majorana neutrinos. Our approach is based on the representation of the amplitude as the momentum integral of a known kernel (proportional to the neutrino propagator) times the generalized forward Compton scattering amplitude n(p1)n(p2)W+(k) →$$ p\left({p}_1^{\prime}\right)p\left({p}_2^{\prime}\right){W}^{-}(k) $$ p p 1 ′ p p 2 ′ W − k , in analogy to the Cottingham formula for the electromagnetic contribution to hadron masses. We construct model-independent representations of the integrand in the low- and high-momentum regions, through chiral EFT and the operator product expansion, respectively. We then construct a model for the full amplitude by interpolating between these two regions, using appropriate nucleon factors for the weak currents and information on nucleon-nucleon (NN) scattering in the 1S0 channel away from threshold. By matching the amplitude obtained in this way to the LO chiral EFT amplitude we obtain the relevant LO contact term and discuss various sources of uncertainty. We validate the approach by computing the analog I = 2 NN contact term and by reproducing, within uncertainties, the charge-independence-breaking contribution to the 1S0NN scattering lengths. While our analysis is performed in the $$ \overline{\mathrm{MS}} $$ MS ¯ scheme, we express our final result in terms of the scheme-independent renormalized amplitude $$ {\mathcal{A}}_{\nu}\left(\left|\mathbf{p}\right|,\left|\mathbf{p}^{\prime}\right|\right) $$ A ν p p ′ at a set of kinematic points near threshold. We illustrate for two cutoff schemes how, using our synthetic data for $$ {\mathcal{A}}_{\nu } $$ A ν , one can determine the contact-term contribution in any regularization scheme, in particular the ones employed in nuclear-structure calculations for isotopes of experimental interest.

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“…• We assume the scalar trilinear terms (A e ) ij to be zero for simplicity. 10 Then, the following five model parameters are left relevant:…”

Section: Setupmentioning

confidence: 99%

Supersymmetric interpretation of the muon g – 2 anomaly

Endo

Hamaguchi

Iwamoto

et al. 2021

J. High Energ. Phys.

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The Fermilab Muon g− 2 collaboration recently announced the first result of measurement of the muon anomalous magnetic moment (g− 2), which confirmed the previous result at the Brookhaven National Laboratory and thus the discrepancy with its Standard Model prediction. We revisit low-scale supersymmetric models that are naturally capable to solve the muon g− 2 anomaly, focusing on two distinct scenarios: chargino-contribution dominated and pure-bino-contribution dominated scenarios. It is shown that the slepton pair-production searches have excluded broad parameter spaces for both two scenarios, but they are not closed yet. For the chargino-dominated scenario, the models with $$ {m}_{{\tilde{\mu}}_{\mathrm{L}}}\gtrsim {m}_{{\tilde{\chi}}_1^{\pm }} $$ m μ ˜ L ≳ m χ ˜ 1 ± are still widely allowed. For the bino-dominated scenario, we find that, although slightly non-trivial, the region with low tan β with heavy higgsinos is preferred. In the case of universal slepton masses, the low mass regions with $$ {m}_{\tilde{\mu}} $$ m μ ˜ ≲ 230 GeV can explain the g− 2 anomaly while satisfying the LHC constraints. Furthermore, we checked that the stau-bino coannihilation works properly to realize the bino thermal relic dark matter. We also investigate heavy staus case for the bino-dominated scenario, where the parameter region that can explain the muon g− 2 anomaly is stretched to $$ {m}_{\tilde{\mu}} $$ m μ ˜ ≲ 1.3 TeV.

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Constraints on the two-pion contribution to hadronic vacuum polarization

Cited by 131 publications

References 121 publications

Consequences of chirally enhanced explanations of (g − 2)μ for h → μμ and Z → μμ

Consequences of chirally enhanced explanations of (g − 2)μ for h → μμ and Z → μμ

Determining the leading-order contact term in neutrinoless double β decay

Supersymmetric interpretation of the muon g – 2 anomaly

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