76 research outputs found
Implications of scalar and tensor explanations of RD(∗)
Full text linkAbstract We investigate the implications of scalar and tensor operators proposed to accommodate the hints of lepton flavor universality violation in charged-current B-meson decays. We show that these scenarios unavoidably induce chirality enhanced contributions to charged lepton magnetic moments and Yukawa couplings. By using an effective field theory approach we quantify in a model independent way the connection of the R D ∗ anomaly with the tau g − 2 and the Higgs decay h → τ τ , which can offer an alternative to test these scenarios. Concrete New Physics models giving rise to our setup will be illustrated
Hunting for ALPs with Lepton Flavor Violation
Full text linkWe examine the low-energy signatures of axion-like particles (ALPs) in lepton flavor violating (LFV) processes. By using a dimension-5 effective Lagrangian, we compute the most general ALP contributions to LFV decays of leptons and mesons. The provided expressions are valid for any choice of ALP mass and couplings. We explore the complementarity of different processes, identifying specific patterns to be experimentally tested. Constraints on LFV couplings are derived from existing data and prospects for forthcoming experiments are also discussed. As a by-product, we revisit the possibility of a simultaneous explanation of the observed discrepancies in the muon and electron g−2 through ALP interactions
Testable Axion-Like Particles In The Minimal Linear sigma Model
Full text linkAxion and axion-like particle models are typically affected by a strong fine-tuning problem in conceiving the electroweak and the Peccei-Quinn breaking scales. Within the context of the Minimal Linear σ Model, axion-like particle constructions are identified where this hierarchy problem is solved, accounting for a TeV Peccei-Quinn breaking scale and a pseudoscalar particle with a mass larger than 10 MeV. Potential signatures at colliders and B-factories are discussedThe authors acknowledge partial financial support by the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreements No.690575 and No. 674896. J.A.G and L.M. acknowledge partial financial support by the Spanish Agencia Estatal de Investigación (AEI) and the EU Fondo Europeo de Desarrollo Regional(FEDER) through the project FPA2016-78645-P, and through the Centro de excelencia Severo Ochoa Program under grant SEV-2016-0597. L. M. acknowledges partial financial support by the Spanish MINECO through the “Ramón y Cajal” programme (RYC-2015-17173).J.A.G. and L.M. thank the Physics and Astronomy department “Galileo Galilei” of the Padua University for hospitality during the development of this project. Furthermore, L.M. thanks the Kavli Institute for the Physics and Mathematics of the Universe for hospitality during the development of this projec
BSM physics and lepton flavor nonuniversality in semileptonic b decays
No full textEven though the LHC searches so far did not unveil the new physics particles, B-factories and LHCb hint towards deviations from Lepton Flavor Universality in both the tree-level and loop-induced B-meson semileptonic decays. In this talk I will propose a new leptoquark model that can fully accommodate these deviations and discuss the main predictions that can be tested at LHCb and/or Belle-II.</p
Leptoquark models for the -physics anomalies
No full textInternational audienceThe -physics experiments at LHCb, BaBar and Belle hint towards deviations from Lepton Flavor Universality in both the tree-level and loop-induced meson semileptonic decays. We propose a leptoquark model with light right-handed neutrinos which can accommodate both . We discuss several of its predictions which can be tested in modern day experiments. We also comment on the recent finding at LHCb, namely
Recherche de la nouvelle physique à travers les observables de la physique de la saveur
No full textIndirect searches of physics beyond the Standard Model through flavor physics processes at low energies are complementary to the ongoing efforts at the LHC to observe the New Physic phenomena directly. In this thesis we discuss several scenarios of physics beyond the Standard Model by (a) reusing the effective field theory approach and (b) by considering explicit extensions of the Standard Model, namely the two-Higgs doublet models and the scenarios involving the low energy scalar leptoquark states. Particular emphasis is devoted to the issue of the lepton flavor universality violation in the exclusive decays based on b → sℓℓ and b → cτν, and to the possibility of searching for signs of lepton flavor violation through similar decay modes. A proposal for testing the presence of the light CP-odd Higgs through quarkonia decays is also made.La recherche indirecte des effets de la physique au-delà du Modèle Standard à travers les processus de la saveur est complémentaire aux efforts au LHC pour observer directement la nouvelle physique. Dans cette thèse nous discutons plusieurs scénarios au-delà du Modèle Standard (a) en utilisant une approche basée sur les théories de champs effective et (b) en considérant des extensions explicites du Modèle Standard, à savoir les modèles à deux doublets de Higgs et les scénarios postulant l'existence des bosons leptoquarks scalaires à basse énergie. En particulier, nous discutons le phénomène de la brisure de l'universalité des couplages leptoniques dans les désintégrations basées sur les transitions b → sℓℓ et b → cτν, et la possibilité de chercher les signatures de la violation de la saveur leptonique à travers les modes de désintégration similaires. Une proposition pour tester la présence d'un boson pseudoscalaire léger à travers les désintégrations des quarkonia est aussi présentée
Connecting flavour at low- and high in SMEFT
No full textInternational audienceWe discuss the high-energy probes of flavor physics operators in the and processes, with , and explore their complementarity with low-energy flavor measurements. We consider the Standard Model Effective Field Theory (SM EFT) as our framework and we discuss two explicit examples: (i) the discrepancies observed in the transition, and (ii) the decays that are currently studied at Belle-II. We also briefly comment on the current status of the SM predictions for these low-energy observables
Looking for New Physics Through the Exclusive Modes
No full textInternational audienceThe Belle-II experiment has recently measured , which appears to be almost larger than its Standard Model (SM) prediction. In this talk, I will critically revisit the status of the SM predictions for the decays, and discuss the interpretation of the recent Belle-II measurement in terms of a general Effective Field Theory, as well as concrete models of physics beyond the SM
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