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While the LHC did not observe direct evidence for physics beyond the standard model, indirect hints for new physics were uncovered in the flavour sector in the decays $B\to K^*\mu^+\mu^-$, $B\to K\mu^+\mu^-/B\to Ke^+e^-$,…

High Energy Physics - Phenomenology · Physics 2016-06-22 Andreas Crivellin

Present measurements of b->c tau nu and b->u tau nu transitions differ from the standard model predictions of lepton flavor universality by almost 4sigma. We examine new physics interpretations of this anomaly. An effective field theory…

High Energy Physics - Phenomenology · Physics 2013-01-04 Svjetlana Fajfer , Jernej F. Kamenik , Ivan Nisandzic , Jure Zupan

The Standard Model (SM) of particle physics was finalized in its current form in the mid-1970s, and has been extensively tested and confirmed ever since, with the discovery of the Higgs boson in 2012 being the last missing piece. While no…

High Energy Physics - Phenomenology · Physics 2021-11-29 Andreas Crivellin , Martin Hoferichter

Lepton Flavour Universality tests with semileptonic $\Lambda_b\to\Lambda_c^*$ decays are important to corroborate the present anomalies in the similar ratios $R_{D^{(*)}}$, and can provide complementary constraints on possible origins of…

High Energy Physics - Phenomenology · Physics 2018-07-31 Philipp Böer , Marzia Bordone , Elena Graverini , Patrick Owen , Marcello Rotondo , Danny van Dyk

Anomalies in (semi)leptonic $B$-meson decays present interesting patterns that might be revealing the shape of the new physics to come. In order to understand the experimental data, we explore symmetry arguments that lead to the hypothesis…

High Energy Physics - Phenomenology · Physics 2015-05-21 Rodrigo Alonso , Benjamín Grinstein , Jorge Martin Camalich

We briefly report on some particular aspects of new physics searches concerning, on the one side, the CKM paradigm and, on the other, the global fit to rare $b\to s \ell\ell$ observables including lepton flavour universality ones. We put…

High Energy Physics - Phenomenology · Physics 2017-11-13 Joaquim Matias

331 models constitute an extension of the Standard Model (SM) obtained by enlarging the SM gauge group $SU(3)_\text{C}\times SU(2)_\text{L}\times U(1)_Y$ to the group $SU(3)_\text{C}\times SU(3)_\text{L}\times U(1)_X$. We investigate how a…

High Energy Physics - Phenomenology · Physics 2019-01-14 Sébastien Descotes-Genon , Marta Moscati , Giulia Ricciardi

Recently, discrepancies of up to $4\,\sigma$ between the different determinations of the Cabibbo angle were observed. This "Cabibbo-angle anomaly" could be explained by lepton flavour universality (LFU) violating New Physics (NP) in the…

High Energy Physics - Phenomenology · Physics 2020-10-28 Antonio M. Coutinho , Andreas Crivellin , Claudio Andrea Manzari

Decays of $B$ mesons with leptons in the final state offer an interesting laboratory to search for possible effects of physics from beyond the Standard Model. In view of puzzling patterns in experimental data, the violation of lepton…

High Energy Physics - Phenomenology · Physics 2021-08-02 Robert Fleischer , Ruben Jaarsma , Gilberto Tetlalmatzi-Xolocotzi

Recent measurements of $b$-hadron decays show a pattern of consistent tensions with the respective Standard Model (SM) predictions. These tensions appear both in the sector of rare flavour-changing neutral currents and in tree-level…

High Energy Physics - Experiment · Physics 2021-07-13 Johannes Albrecht , Danny van Dyk , Christoph Langenbruch

For a long time, global fits of the electroweak sector of the Standard Model (SM) have been used to exploit measurements of electroweak precision observables at lepton colliders (LEP, SLC), together with measurements at hadron colliders…

High Energy Physics - Phenomenology · Physics 2015-06-22 M. Baak , J. Cuth , J. Haller , A. Hoecker , R. Kogler , K. Moenig , M. Schott , J. Stelzer

Precision measures of electroweak and flavour observables, at both low and high energies, are highly complementary to direct searches for New Physics at high-energy colliders. Despite the discovery of the Higgs boson at the Large Hadron…

High Energy Physics - Phenomenology · Physics 2022-03-01 Jonathan Kriewald

Hints of lepton flavor universality violation observed in various flavor ratios such as $R_D$, $R_{D^*}$, $R_{J/\psi}$, $P_\tau^{D^*}$ and $F_L^{D^*}$ in $B\to D^{(*)}\,\ell \, \nu$ and $B_c\to J/\psi \, \ell\, \nu$ charge current decays…

High Energy Physics - Phenomenology · Physics 2022-04-13 Nilakshi Das , Rupak Dutta

In recent years, exciting (indirect) hints for physics beyond the Standard Model (SM) have been accumulated. In particular, semi-leptonic $B$ decays show deviations from the SM predictions, which, due to the ratios $R(K^{(*)})$ and…

High Energy Physics - Phenomenology · Physics 2022-04-27 Andreas Crivellin , Joaquim Matias

The exclusive (B -> K_2 l^+ l^-) decay is studied using the most general, model independent four-fermion interaction. The sensitivity of the ratio of the decay widths when K_2 meson is longitudinally and transversally polarized, the…

High Energy Physics - Phenomenology · Physics 2015-05-30 T. M. Aliev , M. Savci

We use HPQCD's recent lattice QCD determination of $B \to K$ scalar, vector and tensor form factors to determine Standard Model differential branching fractions for $B \to K \ell^+\ell^-$, $B\to K \ell_1^+\ell_2^-$ and $B \to K\nu…

High Energy Physics - Phenomenology · Physics 2023-06-06 W. G. Parrott , C. Bouchard , C. T. H. Davies

We critically examine the potential to disentangle Standard Model (SM) and New Physics (NP) in $B \to K^* \mu^+\mu^-$ and $B\to K^* e^+ e^-$ decays, focusing on $(i)$ the LHCb anomaly, $(ii)$ the search for right-handed currents, and…

High Energy Physics - Phenomenology · Physics 2016-02-03 Sebastian Jäger , Jorge Martin Camalich

We perform a global statistical analysis of the two-Higgs-doublet model with generic sources of flavour violation using \textsf{GAMBIT}. This is particularly interesting in light of deviations from the Standard Model predictions observed in…

High Energy Physics - Phenomenology · Physics 2024-11-27 Peter Athron , Andreas Crivellin , Tomás E. Gonzalo , Syuhei Iguro , Cristian Sierra

We scrutinize the recently further strengthened hints for new physics in semileptonic $B$-meson decays, focusing on the 'clean' ratios of branching fractions $R_K$ and $R_{K^\ast}$ and examining to which pattern of new effects they point…

High Energy Physics - Phenomenology · Physics 2018-12-05 Adrián Carmona , Florian Goertz

Deviation from the standard model prediction is observed in many semileptonic $B$ decays mediated via $b \to c$ charged current interactions. In particular, current experimental measurements of the ratio of branching ratio $R_D$ and…

High Energy Physics - Phenomenology · Physics 2018-06-06 Rupak Dutta , Rajeev N