Contributions of axionlike particles to lepton dipole moments

Marciano, William J.; Masiero, A.; Paradisi, Paride; Passera, M.

doi:10.1103/physrevd.94.115033

Cited by 160 publications

(158 citation statements)

References 62 publications

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“…The mass resolution δM a varies from 7 − 70 MeV at BaBar [67] and comparable resolution at Belle II across the 100 MeV < M a < 10 GeV range; these values are consistent with the BaBar M γγ resolution at the π 0 mass rescaled to higher/lower masses [68]. In addition to the 3γ search mode, we also considered exclusive e + e − → e + e − a, a → γγ production [38] and found it to be subdominant to other channels. At proton fixedtarget experiments, Ref.…”

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confidence: 56%

Searching for Axionlike Particles in Flavor-Changing Neutral Current Processes

2017

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We propose new searches for axion-like particles (ALPs) produced in flavor-changing neutral current (FCNC) processes. This proposal exploits the often-overlooked coupling of ALPs to W ± bosons, leading to FCNC production of ALPs even in the absence of a direct coupling to fermions. Our proposed searches for resonant ALP production in decays such as B → K ( * ) a, a → γγ and K → πa, a → γγ could greatly improve upon the current sensitivity to ALP couplings to Standard Model particles. We also determine analogous constraints and discovery prospects for invisibly decaying ALPs.Introduction: Axion-like particles (ALPs) are among the best-motivated candidates for particle extensions of the Standard Model (SM). ALPs arise as the Goldstone bosons of any theory with a Peccei-Quinn symmetry (PQ) [1][2][3], which is a spontaneously broken global symmetry that is anomalous with respect to the SM gauge interactions. PQ symmetries, and hence ALPs, are ubiquitous in theories beyond the SM such as string theory [4][5][6][7] and supersymmetry [8][9][10]. ALPs were originally motivated by dynamical solutions to the strong-CP problem [1-3], although recent proposals suggest that ALP dynamics could also resolve the hierarchy problem [11].Because ALPs are pseudo-Goldstone bosons, their properties are more constrained than arbitrary scalar fields. In particular, the shift invariance associated with the anomalous symmetry protects ALP masses from radiative corrections and so their masses can naturally take on any value. Furthermore, their interactions with SM fields arise through higher-dimensional (or otherwise suppressed) operators, and these feeble couplings naturally situate ALPs within models of hidden sectors, either as the dark matter candidate itself [12][13][14] or as a mediator through the "axion portal" [15]. This has driven a comprehensive laboratory search program ranging from high-energy collider physics to condensed matter systems (see for example Refs. ).In the simplest models, ALPs couple to the SM gauge boson field strengths according to the anomaly of the corresponding PQ symmetry,

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confidence: 56%

Searching for Axionlike Particles in Flavor-Changing Neutral Current Processes

2017

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“…The leading ALP contributions are given by the one-loop diagrams shown in Fig. 1 (with i = j), as well as by the two-loop light-by-light and vacuum polarization diagrams, which are entirely induced by the aγγ coupling [22]. The expression for a i = F ii 2 (0) can then be written as…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

“…Linear diagrams, which mimic the so-called Barr-Zee contributions [22,32], are typically dominant due to the logarithmic dependence on the ultraviolet cut-off. 3 Their contribution to the dipole form factors reads where…”

Section: J → I γmentioning

confidence: 99%

“…This makes it possible to infer the ALP mass indirectly, through their virtual effects to LFV processes. Another observable which is highly sensitive to ALP couplings is the anomalous magnetic moment of leptons a = (g − 2) /2 [10,22]. This quantity received a lot of attention due to the longstanding ≈ 3.6σ discrepancy between the experimental measurement and the SM prediction, ∆a µ = a exp µ − a SM µ = (27.1 ± 7.3) × 10 −10 [23][24][25], which might be soon clarified by the ongoing analysis at the Muon g-2 experiment (Fermilab) [26].…”

Section: Introductionmentioning

confidence: 99%

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Hunting for ALPs with lepton flavor violation

Cornella

Paradisi

Sumensari

2020

J. High Energ. Phys.

134

137

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We examine the low-energy signatures of axion-like particles (ALPs) in lepton flavor violating (LFV) processes. By using a dimension-5 effective Lagrangian, we compute the most general ALP contributions to LFV decays of leptons and mesons. The provided expressions are valid for any choice of ALP mass and couplings. We explore the complementarity of different processes, identifying specific patterns to be experimentally tested. Constraints on LFV couplings are derived from existing data and prospects for forthcoming experiments are also discussed. As a by-product, we revisit the possibility of a simultaneous explanation of the observed discrepancies in the muon and electron g − 2 through ALP interactions.

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“…Therefore a suitable scenario would be that with a relatively light CPeven flavon and a heavy CP-odd flavon, which would suppress the negative contribution. When m H F ≃ m A F , the flavon contributions would largely cancel one another out for c α ≃ 1 and the remaining (positive) contribution would arise from the corrections to the SM Higgs boson couplings, unless there were large extra positive contributions arising from the CP-odd flavon at the two-loop level: such contributions could arise as long as A F is very light and there was an enhanced one-loop-induced A F γγ coupling, as discussed in [42]. We do not expect such an enhancement in the FNSM, so large values of the mixing matrix element Z l 23 would be required to solve the a μ discrepancy.…”

Section: Matrix Elementsmentioning

confidence: 99%

Searching for lepton flavor violating flavon decays at hadron colliders

et al. 2018

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The search for flavons with a mass of Oð1Þ TeV at current and future colliders might probe low-scale flavor models. We are interested in the simplest model that invokes the Froggatt-Nielsen mechanism with an Abelian flavor symmetry, which includes a Higgs doublet and a Froggatt-Nielsen complex singlet. Assuming a CP conserving scalar potential, there are a CP-even H F and a CP-odd A F flavons with lepton flavor violating (LFV) couplings. The former can mix with the standard-model-like Higgs boson, thereby inducing tree-level LFV Higgs interactions that may be at the reach of the LHC. We study the constraints on the parameter space of the model from low-energy LFV processes, which are then used to evaluate the flavon decay widths and the gg → ϕ → τμ (ϕ ¼ H F ; A F ) production cross section at hadron colliders. After imposing several kinematic cuts to reduce the standard model main background, we find that for m H F about 200-350 GeV, the decay H F → τμ might be at the reach of the LHC for a luminosity in the range 1-3 ab −1 , however, a luminosity of the order of 10 ab −1 would be required to detect the A F → τμ decay. On the other hand, a future 100 TeV pp collider could probe masses as high as Oð10Þ TeV if it reaches an integrated luminosity of at least 20 ab −1 . Therefore, the 100 TeV Collider could work as a flavon factory.

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Contributions of axionlike particles to lepton dipole moments

Cited by 160 publications

References 62 publications

Searching for Axionlike Particles in Flavor-Changing Neutral Current Processes

Searching for Axionlike Particles in Flavor-Changing Neutral Current Processes

Hunting for ALPs with lepton flavor violation

Searching for lepton flavor violating flavon decays at hadron colliders

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