The charm of 331

Buras, Andrzej J.; Colangelo, P.; Fazio, F. De; Loparco, Francesco

doi:10.1007/jhep10(2021)021

Cited by 19 publications

(11 citation statements)

References 54 publications

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“…In previous studies of the 331 model [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][43][44][45][46][47], two Higgs doublets are assumed at the EW scale, which come from the 6 H 1 (chosen to be ρ = 1 without loss of generality) and the 15 H , respectively.…”

Section: The Symmetry Breaking Patternmentioning

confidence: 99%

Bottom quark and tau lepton masses in a toy ${\rm SU}(6)$

Chen¹,

Mao²,

Teng³

2021

Preprint

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We study a toy SU(6) model with the symmetry breaking pattern of the extended 331 symmetry of SU(3) c ⊗ SU(3) W ⊗ U(1) X . A "fermion-Higgs mismatching" symmetry breaking pattern is proposed for more realistic model building. Within such symmetry breaking pattern, only one Higgs doublet develops vacuum expectation value for the spontaneous electroweak symmetry breaking, and gives tree-level top quark mass. A natural VEV splittings in the 331 breaking Higgs fields gives treelevel masses to both bottom quark and tau lepton. The 125 GeV SM-like Higgs boson discovered at the LHC can have Yukawa couplings to bottom quark and tau lepton as in the SM prediction, and this sets the 331 symmetry breaking scale at ∼ O(10) TeV.

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Section: The Symmetry Breaking Patternmentioning

confidence: 99%

Bottom quark and tau lepton masses in a toy ${\rm SU}(6)$

Chen¹,

Mao²,

Teng³

2021

Preprint

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“…allows to bound the Z mediated FCNC transitions of up-type quarks using the constraints established in the down-type quark sector [44]. Such a relation connecting the down-type and up-type quark FCNC processes is a peculiar feature of the 331 model.…”

Section: → Uν ν Transition In the 331 Modelmentioning

confidence: 99%

$c \to u ν{\bar ν}$ transitions of $B_c$ mesons: 331 model facing Standard Model null tests

Colangelo,

De Fazio,

Loparco

2021

Preprint

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The Glashow-Iliopoulos-Maiani mechanism is extremely efficient to suppress the flavour-changing neutral current decays of charmed hadrons induced by the c → u transitions, making such processes particularly sensitive to phenomena beyond the Standard Model. In particular, c → u decays with a neutrino pair in the final state are theoretically appealing due to the small long-distance contributions. Moreover, in the framework of the Standard Model Effective Field Theory (SMEFT), the SU (2) L invariance allows to relate the Wilson coefficients in the effective Hamiltonian governing the c → uν ν decays to the coefficients in the c → u + − Hamiltonian. We analyze the B c → B ( * )+ ν ν decays, for which branching fractions of at most O(10 −16 ) are predicted in the Standard Model including short-and long-distance contributions, so small that they can be considered as null tests. Using SMEFT and the relation to the c → u + − processes we study the largest enhancement achievable in generic new physics scenarios. Then we focus on a particular extension of the Standard Model, the 331 model. SMEFT relations and the connection with c → u + − imply that B(B c → B ( * )+ ν ν) could even reach O(10 −6 ), an extremely large enhancement. A less pronounced effect is found in the 331 model, with O(10 −11 ) predicted branching fractions. Within the 331 model correlations exist among the B c → B ( * )+ ν ν and K → πν ν, B → (X s , K, K * )ν ν channels.

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“…[10] for most recent world averages and global fits. Also theoretically, charm CP violation obtains a lot of attention right now [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25], see earlier Refs. .…”

Section: Introductionmentioning

confidence: 98%

A $U$-Spin Anomaly in Charm CP Violation

Schacht¹

2022

Preprint

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Recent LHCb data shows that the direct CP asymmetries of the decay modes D 0 → π + π − and D 0 → K + K − have the same sign, violating an improved U -spin limit sum rule in an unexpected way at 2.1σ. From the new data, we determine for the first time the imaginary part of the CKMsubleading, U -spin breaking ∆U = 1 correction to the U -spin limit ∆U = 0 amplitude. The imaginary part of the ∆U = 0 amplitude is determined by ∆a dir CP . The corresponding strong phases are yet unknown and could be extracted in the future from time-dependent measurements.Assuming O(1) strong phases due to non-perturbative rescattering, we find the ratio of U -spin breaking to U -spin limit contributions to the CKM-subleading amplitudes to be ( 173+85 −74 )%. This highly exceeds the Standard Model (SM) expectation of ∼ 30% U -spin breaking, with a significance of 1.95σ. If this puzzle is confirmed with more data in the future, in the SM it would imply the breakdown of the U -spin expansion in CKM-subleading amplitudes of charm decays. The other solution are new physics models that generate an additional ∆U = 1 operator, leaving the U -spin power expansion intact. Examples for the latter option are an extended scalar sector or flavorful Z models.

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The charm of 331

Cited by 19 publications

References 54 publications

Bottom quark and tau lepton masses in a toy ${\rm SU}(6)$

Bottom quark and tau lepton masses in a toy ${\rm SU}(6)$

$c \to u ν{\bar ν}$ transitions of $B_c$ mesons: 331 model facing Standard Model null tests

A $U$-Spin Anomaly in Charm CP Violation

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