Explaining the lepton non-universality at the LHCb and CMS within a unified framework

Biswas, Sanjoy; Chowdhury, Debtosh; Han, S.; Lee, Seung Joon

doi:10.1007/jhep02(2015)142

Cited by 68 publications

(39 citation statements)

References 84 publications

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“…1 Previous measurements [3,4] had significantly larger uncertainties and were consistent with the SM prediction, which is R K = 1 to an excellent approximation [5]. Theory interpretations of the recent R K data are given in [6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 69%

Diagnosing lepton-nonuniversality in b → sℓℓ

Hiller

Schmaltz

2015

J. High Energ. Phys.

125

111

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Ratios of branching fractions of semileptonic B decays, (B → Hµµ) over (B → Hee) with H = K, K * , X s , K 0 (1430), φ, . . . are sensitive probes of lepton universality. In the Standard Model, the underlying flavor changing neutral current process b → s is lepton flavor universal. However models with new flavor violating physics above the weak scale can give substantial non-universal contributions. The leading contributions from such new physics can be parametrized by effective dimension six operators involving left-or right-handed quarks. We show that in the double ratios R Xs /R K , R K * /R K and R φ /R K the dependence on new physics coupling to left-handed quarks cancels out. Thus a measurement of any of these double ratios is a clean probe of flavor nonuniversal physics coupling to right-handed quarks. We also point out that the observables R Xs , R K * , R K 0 (1430) and R φ depend on the same combination of Wilson coefficients and therefore satisfy simple consistency relations.

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Section: Introductionmentioning

confidence: 69%

Diagnosing lepton-nonuniversality in b → sℓℓ

Hiller

Schmaltz

2015

J. High Energ. Phys.

125

111

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“…Nevertheless, it is intriguing that many of the discrepancies can be simultaneously explained by assuming new physics contributions to the Wilson coefficients of 4-fermion operators with a band s-quark and 2 leptons [4][5][6][7][8][9][10][11][12][13][14][15]. Such contributions can be easily generated in explicit models through the exchange of a new Z gauge boson [16][17][18][19][20][21][22][23][24][25][26] or leptoquarks [11,[27][28][29][30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Lepton flavor non-universality in B-meson decays from a U(2) flavor model

Falkowski

Nardecchia

Ziegler

2015

J. High Energ. Phys.

125

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Abstract:We address the recent anomalies in semi-leptonic B-meson decays using a model of fermion masses based on the U(2) flavor symmetry. The new contributions to b → s transitions arise due to a tree-level exchange of a Z vector boson gauging a U(1) subgroup of the flavor symmetry. They are controlled by a single parameter and are approximately aligned to the Standard Model prediction, with constructive interference in the e-channel and destructive interference in the µ-channel. The current experimental data on semi-leptonic B-meson decays can be very well reproduced without violating existing constraints from flavor violation in the quark and lepton sectors. Our model will be tested by new measurements of b → s transitions and also by future electroweak precision tests, direct Z searches, and µ-e conversion in nuclei.

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“…On the other hand, bremsstrahlung effects largely cancel in the experimental observable, and results for B → Ke + e − are consistent with SM expectations. The LHCb results for the B → K ( * ) µ + µ − angular distributions and R K have attracted much theoretical attention [12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28]. References [13,16,17,18,19,20,21,23,24,27] proposed the existence of particles at or above 1 TeV which induce new and non-universal lepton interactions.…”

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confidence: 99%

Lepton Flavor Violation inBDecays?

2015

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The LHCb Collaboration's measurement of R K = B(B + → K + µ + µ − )/B(B + → K + e + e − ) lies 2.6σ below the Standard Model prediction. Several groups suggest this deficit to result from new lepton non-universal interactions of muons. But non-universal leptonic interactions imply lepton flavor violation in B-decays at rates much larger than are expected in the Standard Model. A simple model shows that these rates could lie just below current limits. An interesting consequence of our model, that B(75, is compatible with recent measurements of these rates. We stress the importance of searches for lepton flavor violations, especially for B → Kµe, Kµτ and B s → µe,

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Explaining the lepton non-universality at the LHCb and CMS within a unified framework

Cited by 68 publications

References 84 publications

Diagnosing lepton-nonuniversality in b → sℓℓ

Diagnosing lepton-nonuniversality in b → sℓℓ

Lepton flavor non-universality in B-meson decays from a U(2) flavor model

Lepton Flavor Violation inBDecays?

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