Correlation between $$ {R}_{D^{\left(\ast \right)}} $$ and top quark FCNC decays in leptoquark models

Kim, Tae Jeong; Ko, Pyungwon; Li, Jinmian; Park, Ji Won; Wu, Peiwen

doi:10.1007/jhep07(2019)025

Cited by 35 publications

(12 citation statements)

References 104 publications

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“…As leptoquarks, they appear together in models which tackle the flavour anomalies in the R K ( * ) and R D ( * ) observables [38][39][40][41][42]. S 1 coupling as a leptoquark is able to explain R D ( * ) (see, for example [43,44]) while S 3 coupling as a leptoquark is able explain R K ( * ) [45][46][47][48][49][50][51]. However, in order to generate neutrino mass in this model, the fermion content of the chosen effective operators forces us to have one of either S 1 or S 3 coupling as a leptoquark, and the other as a diquark.…”

Section: The Modelmentioning

confidence: 99%

Radiative neutrino mass model from a mass dimension-11 ∆L = 2 effective operator

Gargalionis

Popa-Mateiu

Volkas

2020

J. High Energ. Phys.

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We present the first detailed phenomenological analysis of a radiative Majorana neutrino mass model constructed from opening up a ∆L = 2 mass-dimension-11 effective operator constructed out of standard model fields. While three such operators are generated, only one dominates neutrino mass generation, namely O 47 = L C LQ C QQQ C HH, where L denotes lepton doublet, Q quark doublet and H Higgs doublet. The underlying renormalisable theory contains the scalars S 1 ∼ (3, 1, 1/3) coupling as a diquark, S 3 ∼ (3, 3, 1/3) coupling as a leptoquark, and Φ 3 ∼ (3, 3, 2/3), which has no Yukawa couplings but does couple to S 1 and S 3 in addition to the gauge fields. Neutrino masses and mixings are generated at two-loop order. A feature of this model that is different from many other radiative models is the lack of proportionality to any quark and charged-lepton masses of the neutrino mass matrix. One consequence is that the scale of new physics can be as high as 10 7 TeV, despite the operator having a high mass dimension. This raises the prospect that ∆L = 2 effective operators at even higher mass dimensions may, when opened up, produce phenomenologically-viable radiative neutrino mass models. The parameter space of the model is explored through benchmark slices that are subject to experimental constraints from charged lepton flavour-violating decays, rare meson decays and neutral-meson mixing. The acceptable parameter space can accommodate the anomalies in R K ( * ) and the anomalous magnetic moment of the muon.

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Section: The Modelmentioning

confidence: 99%

Radiative neutrino mass model from a mass dimension-11 ∆L = 2 effective operator

Gargalionis

Popa-Mateiu

Volkas

2020

J. High Energ. Phys.

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“…To illustrate how L np may be generated by renormalizable NP interactions, we look at the leptoquark (LQ) scenario. Amongst those that have been explored in the literature [12][13][14][15][16][17][18][19][20][21][22], with couplings to SM fermions which conserve baryon and lepton numbers and respect SM gauge symmetries, the LQs (with their SU(3) c × SU(2) L × U(1) Y assignments) that can bring about L np are S 1 3 , 1, 4/3 , S 2 (3, 2, 7/6),S 2 (3, 2, 1/6), and S 3 3 , 3, 1/3 , which are spinless, and V 1 (3, 1, 2/3), V 2 3 , 2, 5/6 , and V 3 (3, 3, 2/3), which have spin 1. The SU(2) L doublets (triplets) S 2 ,S 2 , and V 2 (S 3 and V 3 ) each have two (three) components having different electric charges.…”

Section: Leptoquark Modelmentioning

confidence: 99%

“…Many extensions of the SM do not preserve lepton-flavor number, and the corresponding parameters have been tightly restricted by the negative outcomes of the various searches conducted so far in the decays of kaons, B mesons, and charged leptons, among others [1][2][3][4][5][6][7][8][9][10][11]. The most common examples of NP exhibiting LFV include leptoquarks [12][13][14][15][16][17][18][19][20][21][22], heavy neutrinos [23][24][25][26][27][28][29][30][31][32], gauged U(1) extensions of the SM with their associated Z gauge bosons [33][34][35][36][37][38][39][40][41], and multi-Higgs models [42][43][44][45][46][47]…”

mentioning

confidence: 99%

Charged-lepton-flavor violation in |ΔS| = 1 hyperon decays

He¹,

Tandean²,

Valencia³

2019

J. High Energ. Phys.

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Studies of lepton-flavor violation in strangeness-changing (|∆S| = 1) transitions have a long tradition in the kaon sector where they provide some of the strongest limits on physics beyond the standard model. Recent hints of violation of lepton-flavor universality in B-meson decays have revived interest in lepton-flavor violation as the two phenomena appear simultaneously in many extensions of the standard model. At the same time, the LHCb experiment has produced new results for the hyperon process Σ + → pµ + µ − and may be in a position to study other rare hyperon decay modes. With this in mind, we investigate |∆S| = 1 hyperon decays into different-flavor lepton pairs e ± µ ∓ in a model-independent manner and contrast the coverage of parameter space that can be achieved with what is known from kaon modes. We include a comparison with selected two-body leptonic decays of charged mesons, with K → πνν modes, with µ → e conversion, and with lepton-flavor violating decays of other neutral mesons, all of which constrain the same parameter space in a complementary way.

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“…[45]. Models with one or more LQ states, which are colored bosons and couple to both quarks and leptons, are one of the most popular scenarios to explain the R D ( * ) and R K ( * ) anomalies [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63]. In ref.…”

Section: Introductionmentioning

confidence: 99%

Phenomenology of decays in a scalar leptoquark model *

2019

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During the past few years, hints of Lepton Flavour Universality (LFU) violation have been observed in b → cτν and b → s + − transitions. Recently, the D * and τ polarization fractions P D * L and P τ L in B → D * τν decay have also been measured by the Belle collaboration. Motivated by these intriguing results, we revisit the R D ( * ) and R K ( * ) anomalies in a scalar leptoquark (LQ) model, in which two scalar LQs, one being SU (2) L singlet and the other SU (2) L triplet, are introduced simultaneously. We consider five b → cτν mediated decays, B → D ( * ) τν, B c → η c τν, B c → J/ψτν, and Λ b → Λ c τν, and focus on the LQ effects on the q 2 distributions of the branching fractions, the LFU ratios, and the various angular observables in these decays. Under the combined constraints by the available data on R D ( * ) , R J/ψ , P τ L (D * ), and P D * L , we perform scans for the LQ couplings and make predictions for a number of observables. It is found numerically that both the differential branching fractions and the LFU ratios are largely enhanced by the LQ effects, with the latter being expected to provide testable signatures at the SuperKEKB and High-Luminosity LHC experiments.results of R D and R D * with a semileptonic tagging method [94,95]. The measured values are R exp D = 0.307 ± 0.037 (stat.) ± 0.016 (syst.) and R exp D * = 0.283 ± 0.018 (stat.) ± 0.014 (syst.). After including this new measurement, the world averages become to R avg, 2019 D = 0.337 ± 0.030

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Correlation between $$ {R}_{D^{\left(\ast \right)}} $$ and top quark FCNC decays in leptoquark models

Cited by 35 publications

References 104 publications

Radiative neutrino mass model from a mass dimension-11 ∆L = 2 effective operator

Radiative neutrino mass model from a mass dimension-11 ∆L = 2 effective operator

Charged-lepton-flavor violation in |ΔS| = 1 hyperon decays

Phenomenology of decays in a scalar leptoquark model *

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