Probing charged lepton flavor violation with axion-like particles at Belle II

Cheung, Kingman; Soffer, A.; Wang, Zeren Simon; Wu, Y. G.

doi:10.1007/jhep11(2021)218

“…In refs. [11][12][13][14], the dark photon production from the dark Higgs decay at the FASER and other experiments [15][16][17][18] was studied. Using a large number of the dark Higgs bosons produced by heavy meson decays through the scalar mixing with the SM Higgs boson, it was shown that the sensitivity to the dark photon parameters can be enlarged.…”

Section: Introductionmentioning

confidence: 99%

Dark photon from light scalar boson decays at FASER

Araki

¹

,

Asai

²

,

Otono

³

et al. 2021

J. High Energ. Phys.

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FASER is one of the promising experiments which search for long-lived particles beyond the Standard Model. In this paper, we focus on dark photon associating with an additional U(1) gauge symmetry, and also a scalar boson breaking this U(1) gauge symmetry. We study the sensitivity to the dark photon originated from U(1)-breaking scalar decays. We find that a sizable number of dark photon signatures can be expected in wider parameter space than previous studies.

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“…In [43][44][45], on the other hand, one finds a more generic analysis of ALP signatures in cLFV phenomena, where both muonic and tauonic decay modes are entertained. Searches for τ → ℓX at Belle II are also expected to play a major part in the ongoing probing of flavourviolating new physics, either via prompt decays of possibly short-lived ALPs or, in the case of long-lived ALPs, via displaced vertices or missing energy [46,47]. These processes are, however, beyond the scope of the present work.…”

Section: Introductionmentioning

confidence: 91%

“…The expected number of signal events in the signal bin depends on the µ + → e + X branching ratio B as nr s = B N µ E s I s = B N b E I s , where I s is defined in analogy to (46). Using the LO approximation H s (E ′ ) ∝ δ(E ′ − E X ), we have I s = erf(z 90 / 2) = 0.9.…”

Section: Experimental Sensitivitymentioning

confidence: 99%

High-precision muon decay predictions for ALP searches

Banerjee

¹

,

Coutinho

²

,

Engel

³

et al. 2023

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We present an improved theoretical prediction of the positron energy spectrum for the polarised Michel decay \mu^+\to e^+ \nu_e\bar{\nu}_\muμ+→e+νeν‾μ. In addition to the full next-to-next-to-leading order correction of order \alpha^2α2 in the electromagnetic coupling, we include logarithmically enhanced terms at even higher orders. Logarithms due to collinear emission are included at next-to-leading accuracy up to order \alpha^4α4. At the endpoint of the Michel spectrum, soft photon emission results in large logarithms that are resummed up to next-to-next-to-leading logarithmic accuracy. We apply our results in the context of the MEG II and Mu3e experiments to estimate the impact of the theory error on the branching ratio sensitivity for the lepton-flavour-violating decay \mu^+\to e^+ Xμ+→e+X of a muon into an axion-like particle XX.

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“…Signatures of directly detectable or escaping long-lived particles at B factories have also been discussed in refs. [30,[46][47][48][49][50][51][52][53][54][55][56][57][58][59] This paper is organized as follows: section 2 contains the theoretical framework of the RPV scenario. This includes the effective Lagrangian with the RPV terms and the calculation of the matrix elements, which we estimate using an effective BNV Lagrangian.…”

Section: Jhep02(2023)224mentioning

confidence: 99%

Probing R-parity violation in B-meson decays to a baryon and a light neutralino

Dib

¹

,

Helo

²

,

Lyubovitskij

³

et al. 2023

J. High Energ. Phys.

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We propose a search for B meson decays to a baryon plus missing energy at the Belle II experiment to probe supersymmetry with a GeV-scale lightest neutralino $$ {\overset{\sim }{\chi}}_1^0 $$ χ ~ 1 0 and R-parity violation (RPV). We perform analytic computations of the signal branching fractions in the framework of effective field theory, with a single nonzero RPV operator $$ {\lambda}_{ij3}^{\prime \prime }{\overline{U}}_i^c{\overline{D}}_j^c{\overline{D}}_3^c $$ λ ij 3 ′ ′ U ¯ i c D ¯ j c D ¯ 3 c , where i, j = 1, 2. The hadronic form factors are calculated using an SU(3) phenomenological Lagrangian approach for the proton, as well as several hyperons and charmed baryons. Since the decay of the neutralino is kinematically and CKM suppressed in this theoretical scenario, it decays outside the detector and appears experimentally only as missing energy. We detail the analysis techniques at the experimental level and estimate the background in the $$ {B}^{+}\to p{\overset{\sim }{\chi}}_1^0 $$ B + → p χ ~ 1 0 search using published results for $$ {B}^{+}\to {K}^{+}\nu \overline{\nu} $$ B + → K + ν ν ¯ . Our final sensitivity plots are shown for both $$ {\lambda}_{113}^{\prime \prime } $$ λ 113 ′ ′ versus the squark mass $$ {m}_{\tilde{q}} $$ m q ~ and $$ {\lambda}_{113}^{\prime \prime }/{m}_{\tilde{q}}^2 $$ λ 113 ′ ′ / m q ~ 2 versus the neutralino mass $$ {m}_{{\overset{\sim }{\chi}}_1^0} $$ m χ ~ 1 0 . We find that the search at Belle II could probe $$ {\lambda}_{113}^{\prime \prime }/{m}_{\tilde{q}}^2 $$ λ 113 ′ ′ / m q ~ 2 down to the order of 10−8 GeV−2 in the kinematically allowed $$ {m}_{{\overset{\sim }{\chi}}_1^0} $$ m χ ~ 1 0 range. We also obtain current limits on $$ {\lambda}_{123}^{\prime \prime } $$ λ 123 ′ ′ by recasting an existing search interpreted as $$ {B}^0\to {\Lambda}^0{\overset{\sim }{\chi}}_1^0 $$ B 0 → Λ 0 χ ~ 1 0 , and comment about searches for $$ {B}^{+}\to {\Sigma}^{+}{\overset{\sim }{\chi}}_1^0 $$ B + → Σ + χ ~ 1 0 , $$ {B}^0\to {\Sigma}^0{\chi}_1^0 $$ B 0 → Σ 0 χ 1 0 , $$ {B}^{+}\to {\Lambda}_c^{+}{\overset{\sim }{\chi}}_1^0 $$ B + → Λ c + χ ~ 1 0 , and $$ {B}^{+}\to {\Xi}_c^{+}{\overset{\sim }{\chi}}_1^0 $$ B + → Ξ c + χ ~ 1 0 . In closing, we briefly discuss potential searches at the LHCb and BESIII experiments.

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Probing charged lepton flavor violation with axion-like particles at Belle II

Cited by 16 publications

References 102 publications

Dark photon from light scalar boson decays at FASER

Dark photon from light scalar boson decays at FASER

High-precision muon decay predictions for ALP searches

Probing R-parity violation in B-meson decays to a baryon and a light neutralino

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