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Chen, Chuan Hung; Nomura, Takaaki; Okada, Hiroshi

doi:10.1016/j.physletb.2017.10.005

Cited by 135 publications

(68 citation statements)

References 76 publications

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“…W gauge bosons [11,14,53,54] 3. Leptoquarks [9,10,12,13,15,16,19,20,42,[55][56][57][58][59][60] Models with charged Higgses lead to (too) large effects in the total B c lifetime [61] and, depending on the coupling structure, can also be disfavored by the q 2 distribution [62][63][64]. Interestingly, if the couplings of the charged Higgs are chosen in such a way that they are compatible with the measured q 2 distribution, these models are ruled out by direct searches [65].…”

Section: Jhep09(2017)040mentioning

confidence: 99%

“…with 20) and C 23 R is obtained from C 23 L by L ↔ R. We will assume that λ R 32 is small compared to λ L 32 . The world average of the measurement of a µ ≡ (g − 2) µ /2 is completely dominated by the Brookhaven experiment E821 [76] and is given by [77] a exp µ = (116 592 091 ± 54 ± 33) × 10 −11 where the first error is statistical and the second one is systematic.…”

Section: A µ and τ → µγmentioning

confidence: 99%

“…Therefore, it is well motivated to search for a simultaneous explanation of these two anomalies [8][9][10][11][12][13][14][15][16][17][18][19][20]. Furthermore, since a e agrees with the SM prediction, also a µ can be considered as a LFUV quantity and one can address it together with R(D ( * ) ) and/or b → sµ + µ − [13,[21][22][23].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Simultaneous explanation of R(D (∗)) and b→sμ + μ −: the last scalar leptoquarks standing

Crivellin

Müller

Ota

2017

J. High Energ. Phys.

322

254

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Over the past years, experiments accumulated intriguing hints for new physics (NP) in flavor observables, namely in the anomalous magnetic moment of the muon (a µ ), in R(D ( * ) ) = Br(B → D ( * ) τ ν)/Br(B → D ( * ) ν) and in b → sµ + µ − transitions, which are all at the 3 − 4 σ level. In this article we point out that one can explain the R(D ( * ) ) anomaly using two scalar leptoquarks (LQs) with the same mass and coupling to fermions related via a discrete symmetry: an SU(2) L singlet and an SU(2) L triplet, both with hypercharge Y = −2/3. In this way, potentially dangerous contributions to b → sνν are avoided and non-CKM suppressed effects in R(D ( * ) ) can be generated. This allows for smaller overall couplings to fermions weakening the direct LHC bounds. In our model, R(D ( * ) ) is directly correlated to b → sτ + τ − transitions where an enhancement by orders of magnitude compared to the standard model (SM) is predicted, such that these decay modes are in the reach of LHCb and BELLE II. Furthermore, one can also naturally explain the b → sµ + µ − anomalies (including R(K)) by a C 9 = −C 10 like contribution without spoiling µ − e universality in charged current decays. In this case sizable effects in b → sτ µ transitions are predicted which are again well within the experimental reach. One can even address the longstanding anomaly in a µ , generating a sizable decay rate for τ → µγ. However, we find that out of the three anomalies R(D ( * ) ), b → sµ + µ − and a µ only two (but any two) can be explained simultaneously. We point out that a very similar phenomenology can be achieved using a vector leptoquark SU(2) L singlet with hypercharge 2/3. In this case, no tuning between couplings is necessary, but the model is non-renormalizable.

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Section: Jhep09(2017)040mentioning

confidence: 99%

Section: A µ and τ → µγmentioning

confidence: 99%

See 1 more Smart Citation

Simultaneous explanation of R(D (∗)) and b→sμ + μ −: the last scalar leptoquarks standing

Crivellin

Müller

Ota

2017

J. High Energ. Phys.

322

254

View full text Add to dashboard Cite

show abstract

“…Previous analyses in the literature have considered various ad hoc extensions of the Standard Model suitable to accommodate the anomalies, in particular including new gauge bosons [25][26][27][28][29][30][31][32][33][34][35], leptoquarks [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] and general effective field theory frameworks [51][52][53][54][55]. 2 Anomalies in R K , and b → s processes, have also been addressed in Randall-Sundrum [56][57][58] and flat space [59] extra dimensional scenarios.…”

Section: Jhep07(2017)102mentioning

confidence: 99%

Lepton-flavor universality violation in R K and R D ∗ $$ {R}_{D^{{}_{\left(\ast \right)}}} $$ from warped space

Megías

Quirós

Salas

2017

J. High Energ. Phys.

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Some anomalies in the processes b → s ( = µ, e) and b → c ν ( = τ, µ, e), in particular in the observables R K and R D ( * ) , have been found by the BaBar, LHCb and Belle collaborations, leading to a possible lepton flavor universality violation. If these anomalies were confirmed they would inevitably lead to physics beyond the Standard Model. In this paper we try to accommodate the present anomalies in an extra dimensional theory, solving the naturalness problem of the Standard Model by means of a warped metric with a strong conformality violation near the infra-red brane. The R K anomaly can be accommodated provided that the left-handed bottom quark and muon lepton have some degree of compositeness in the dual theory. The theory is consistent with all electroweak and flavor observables, and with all direct searches of Kaluza-Klein electroweak gauge bosons and gluons. The fermion spectrum, and fermion mixing angles, can be reproduced by mostly elementary right-handed bottom quarks, and tau and muon leptons. Moreover the R D ( * ) anomaly requires a strong degree of compositeness for the left-handed tau leptons, which turns out to be in tension with experimental data on the g Z τ L coupling, possibly unless some degree of fine-tuning is introduced in the fixing of the CKM matrix.

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“…Furthermore, also RðJ=ΨÞ points towards the violation of LFU in b → cτν processes [10]. This suggests a possible connection between these two classes of decays and motivates the investigation of simultaneous explanations [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30].…”

mentioning

confidence: 99%

B Meson Anomalies in a Pati-Salam Model within the Randall-Sundrum Background

2018

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Lepton number as a fourth color is the intriguing theoretical idea of the famous Pati-Salam (PS) model. While in conventional PS models, the symmetry breaking scale and the mass of the resulting vector leptoquark are stringently constrained by K L → μe and K → πμe, the scale can be lowered to a few TeV by adding vectorlike fermions. Furthermore, in this case, the intriguing hints for lepton flavor universality violation in b → sμ þ μ − and b → cτν processes can be addressed. Such a setup is naturally achieved by implementing the PS gauge group in the five-dimensional Randall-Sundrum background. The PS symmetry is broken by boundary conditions on the fifth dimension, and the resulting massive vector leptoquark automatically has the same mass scale as the vectorlike fermions and all other resonances. We consider the phenomenology of this model in the context of the hints for lepton flavor universality violation in semileptonic B decays. Assuming flavor alignment in the down sector, we find that in b → sl þ l − transitions, the observed deviations from the standard model predictions [including RðKÞ and RðK Ã Þ can be explained with natural values for the free parameters of the model. Even though we find sizable effects in RðDÞ, RðD Ã Þ, and RðJ=ΨÞ, one cannot account for the current central values in the constrained setup of our minimal model due to the stringent constraints from D −D mixing and τ → 3μ.

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Excesses of muon g − 2,RD(⁎), andR

Cited by 135 publications

References 76 publications

Simultaneous explanation of R(D (∗)) and b→sμ + μ −: the last scalar leptoquarks standing

Simultaneous explanation of R(D (∗)) and b→sμ + μ −: the last scalar leptoquarks standing

Lepton-flavor universality violation in R K and R D ∗ $$ {R}_{D^{{}_{\left(\ast \right)}}} $$ from warped space

B Meson Anomalies in a Pati-Salam Model within the Randall-Sundrum Background

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