Scalar leptoquarks from grand unified theories to accommodate the 
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-physics anomalies

Bečirević, Damir; Doršner, Ilja; Fajfer, Svjetlana; Faroughy, Darius A.; Košnik, Nejc; Sumensari, Olcyr

doi:10.1103/physrevd.98.055003

Cited by 197 publications

(145 citation statements)

References 117 publications

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“…Also in this case, the Yukawa interactions present the same flavor structure discussed in 3.2: dominant couplings to third-generation fermions, with small couplings to left-handed light-generation fermions and negligible couplings to right-handed light-generation fermions. The R 2 leptoquark was recently proposed as a solution to the R D ( * ) anomalies [36]. However in our model the R 2 contributions to these observables are negligible due to the smallness of the light-generation right-handed couplings.…”

Section: Constraints On the New Fieldsmentioning

confidence: 77%

“…Due to the relatively low scale of new physics hinted at by the charged-current anomalies, high-p T constraints are indeed quite relevant [19][20][21][22][23][24][25][26][27]. Given the success of some EFT approaches and simplified models in describing available data, the attention has shifted recently towards the development of more complete (and more complex) models with a consistent ultraviolet (UV) behavior (see in particular [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]).…”

Section: Introductionmentioning

confidence: 99%

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Revisiting the vector leptoquark explanation of the B-physics anomalies

Cornella

Fuentes-Martín

Isidori

2019

J. High Energ. Phys.

175

209

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We present a thorough investigation of the vector leptoquark hypothesis for a combined explanation of the B-physics anomalies. We analyze this hypothesis from a twofold perspective, taking into account recent results from B-physics observables and high-p T searches. First, using a simplified model, we determine the general conditions for a successful lowenergy fit in presence of right-handed leptoquark couplings (neglected in previous analyses). Second, we show how these conditions, in particular a sizable 2-3 family mixing, can be achieved in a motivated ultraviolet completion. Our analysis reinforces the phenomenological success of the vector leptoquark hypothesis in addressing the anomalies, and its compatibility with motivated extensions of the Standard Model based on the idea of flavor non-universal gauge interactions. The implications of right-handed leptoquark couplings for a series of key low-energy observables, namely B s → τ τ and τ → µ lepton flavor violating processes, both in τ and in B decays, are discussed in detail. The role of the ultraviolet completion in precisely estimating other low-energy observables, most notably ∆F = 2 amplitudes, is also addressed. also [32,37]).We provide a detailed implementation of the U 1 leptoquark in a renormalizable model based on the (flavor non-universal) gauge group SU (4) 3 × SU (3) 1+2 × SU (2) L × U (1) , which in turn can be embedded in PS 3 [31]. In this context, we complement the simplified-model analysis by including oneloop contributions to low-energy observables (most notably ∆F = 2 amplitudes and dipole operators) which can be reliably computed only within a UV-complete framework.The paper is organized as follows. In Section 2 we present the simplified-model analysis: we introduce the Lagrangian describing the U 1 couplings to SM fermions, and analyze its low-energy limit. We discuss all the observables insensitive to the UV completion (Section 2.2), which are later used to fit low-energy data (Section 2.3). We finally comment on the high-p T constraints (Section 2.4).The UV-complete model is presented and discussed in Section 3: on the model-building side we pay particular attention to the flavor structure of the model (Section 3.2); on the phenomenological side we present complete expressions for the UV-dependent (loop-induced) observables, which were omitted in the low-energy fit (Section 3.3). The results are summarized in Section 4.

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Section: Constraints On the New Fieldsmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Revisiting the vector leptoquark explanation of the B-physics anomalies

Cornella

Fuentes-Martín

Isidori

2019

J. High Energ. Phys.

175

209

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“…4. The case of imaginary WCs in this context was first discussed in [40], and later also in [39,[41][42][43][44]. In this case, Fig.…”

Section: Sm Prediction Measurementmentioning

confidence: 90%

“…Another single mediator solution that has been discussed in the literature is the so-called R 2 (3, 2, 7/6) Leptoquark [38,39]. which, contrary to the S 1 (3, 1, 1/3) Leptoquark mediator, generates C LL S ≈ +8C LL T (see the sign difference) at the m b scale 2 .…”

Section: Sm Prediction Measurementmentioning

confidence: 99%

B -meson charged current anomalies: The post-Moriond 2019 status

Bardhan

Ghosh

2019

Phys. Rev. D

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In this note, we discuss the impact of the recent Belle result on the various theoretical explanations of the RD and RD * anomalies. The pure tensor explanation, which was strongly disfavoured by the measurements of F D * L and high-pT p p → τ ν searches before Moriond, is now completely allowed because of reduction of the experimental world-average. Moreover, the pure right-chiral vector solution (involving right-chiral neutrinos) has now moved into the 2σ allowed range of the LHC p p → τ ν searches. We also critically re-examine the bound on B(B − c → τ −ν τ ) from LEP data and show that the bound is considerably weaker than the number 10% often used in the recent literature.The Belle collaboration has recently published results for R D and R D * with a semileptonic tag [1,2], and their result is consistent with the Standard Model (SM) expectation within 1.2σ. Consequently, the experimental world average has moved towards the SM. However, the tension between the experimental world average and the SM expectation is still more than 3σ, and thus, it is interesting to re-examine the status of the various New Physics (NP) explanations in view of the new worldaverage. In Table. I below, we collect all the experimental results related to this anomaly. SM prediction Measurement04 [6] −0.38 +0.55 −0.53 [9, 10] F D * L 0.46 ± 0.04 0.60 ± 0.087 [11] R J/ψ 0.290 0.71 ± 0.25 [12] TABLE I. Observables, their SM predictions and the experimentally measured values. The pre-Moriond experimental averages for RD and RD * are based on [9, 10, 13-19].The most general effective Lagrangian for the decay b → c τ −ν τ involving mass dimension-6 operators and only left-chiral neutrinos can be written asc. If one uses power-counting rules arising from linearlyrealised SU(2) × U(1) gauge invariance, it turns out that the Wilson Coefficient (WC) C RL V , with the possibility of lepton non-universality, is only generated at the mass dimension-8 level [20]. Thus, it is expected to be suppressed compared to the other WCs as long as the scale * bardhan@post.bgu.ac.il † diptimoy.ghosh@iiserpune.ac.in of NP is not too close to the Higgs vacuum expectation value, thus we will ignore it in this analysis. If one also assumes the existence of light right-chiral neutrino(s), as was first done in [21] to solve the R D anomaly, five additional operators can be constructed by the replacement P L → P R in the leptonic currents of Eq. 1. In particular, a pure-right chiral vector current namely,was considered by several authors [22][23][24] , and we will include it in our analysis. As the experimental situation for R D and R D * is far from clear, we do not try to perform a fit to the WCs; for an early global fit, see [25]. Instead, we show how R D and R D * vary with respect to the WCs, and overlay the current 1σ experimental world-average and the corresponding currently allowed values of the WCs.In Fig. 1, we show this for two WCs C LL V and C RR V assuming them to be real. It can be seen from the left 0.20 0.25 0.30 0.35 0.40 0.45 R D 0.90 0.95 1.00 1.05...

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“…Much work has been done in the past few years on the phenomenology of leptoquarks in relation to the flavor anomalies, for some early references, see, e.g., [38,[40][41][42][43][44][45]48]. Here, we limit ourselves to the analysis of but one of these models, the scalar SU(2) triplet S 3 [87][88][89][90][91][92][93][94], which can generate a C µ 9 = −C µ 10 contribution at the tree level, like Model 3 of the previous subsection.…”

Section: Leptoquarksmentioning

confidence: 99%

Implications for new physics in $$b\rightarrow s \mu \mu $$ transitions after recent measurements by Belle and LHCb

2019

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We present a Bayesian analysis of the implications for new physics in semileptonic b → s transitions after including new measurements of R K at LHCb and new determinations of R K * and R K * + at Belle. We perform global fits with 1, 2, 4, and 8 input Wilson coefficients, plus one CKM nuisance parameter to take into account uncertainties that are not factorizable. We infer the 68% and 95.4% credibility regions of the marginalized posterior probability density for all scenarios and perform comparisons of models in pairs by calculating the Bayes factor given a common data set. We then proceed to analyzing a few well-known BSM models that can provide a high energy framework for the EFT analysis. These include the exchange of a heavy Z boson in models with heavy vector-like fermions and a scalar field, and a model with scalar leptoquarks. We provide predictions for the BSM couplings and expected mass values.

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Scalar leptoquarks from grand unified theories to accommodate the B -physics anomalies

Cited by 197 publications

References 117 publications

Revisiting the vector leptoquark explanation of the B-physics anomalies

Revisiting the vector leptoquark explanation of the B-physics anomalies

B -meson charged current anomalies: The post-Moriond 2019 status

Implications for new physics in $$b\rightarrow s \mu \mu $$ transitions after recent measurements by Belle and LHCb

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