# LHCb and Belle II Opportunities for Model Builders

Europe/Berlin
02.430 (Mainz Institute for Theoretical Physics, Johannes Gutenberg University)

### 02.430

#### Mainz Institute for Theoretical Physics, Johannes Gutenberg University

Staudingerweg 9 / 2nd floor, 55128 Mainz
Description
The flavor physics community is patiently preparing for the upcoming physics run of the Belle II experiment, which is expected the deepen our understanding of CP and flavor violation. While no signal of new physics has been observed so far at the LHC in the high-energy frontier, a set of surprising - albeit still inconclusive - hints of violation of lepton flavor universality have been observed in semi-leptonic B-decays by LHCb and the previous B factories BaBar and Belle, renewing the interest in flavor physics of a broader community. The goal of this Topical Workshop is to bring together Belle II and LHCb experimentalists and BSM model builders to discuss the opportunities and new schemes for future Belle II measurements in view of the present results from the LHC. The workshop will have a balanced schedule of theory and experimental talks as well as several discussion sessions to trigger more interaction among the leading experts in the field. The impact is expected on the Belle II community decision-making process about the future search priorities as well as on the determination of future research topics in the theory community. The main objective is to better understand the Belle II potential to uncover new physics.
Contact @ MITP : Sibylle Wittek
• Monday, 28 January
• 12:00 12:15
Introduction to the workshop 15m
• 14:00 14:45
BSM interpretations of R(D(*) 45m
Speaker: Diptimoy Ghosh
• 14:45 15:30
LFU tests in the angular observables of $B \to D^{*} \ell \nu$ 45m
In this talk, I will review a new set of observables sensitive to LFU violation, whose measurements - together with the ones of R(D) and R(D*) - would be extremely of help to understand whether there is indeed presence of NP in $b \to c$ transitions, and moreover to discriminate the shape of it.
Speaker: Marco Fedele
• Tuesday, 29 January
• 10:30 11:15
Status of LFU tests in B-meson decays from LHCb 45m
Speaker: Beatriz García Plana
• 11:15 12:00
Model Independent bounds on SMEFT from flavour physics 45m
Speaker: Mauro Valli
• 14:00 14:45
New perspectives in BSM flavour physics 45m
Speaker: Javi Serra
• Wednesday, 30 January
• 10:30 11:15
LFV B-decays @ Belle-II 45m
Speaker: Alexander Glazov
• 11:15 12:00
Tau decays @ Belle-II 45m
Speaker: Xing-Yu Zhou
• 14:00 14:45
The vector leptoquark saga: from EFT to UV 45m
The vector leptoquark has been shown to be one of the most successful candidates for the combined explanation of B-anomalies. In this talk I will present the high- and low-energy phenomenology of a vector leptoquark coupled to left- and right-handed SM fields, emphasising the differences with respect to the solution involving left-handed couplings only. I will then discuss the general structure and the phenomenology of the Pati Salam Cubed model, which provides a possibile UV completion to this setup.
Speaker: Claudia Cornella
• 14:45 15:30
Explaining B-anomalies by loop effects 45m
Speaker: Federico Mescia
• Thursday, 31 January
• 10:30 11:15
B-decays with missing energy @ Belle-II 45m
Speaker: Lu Cao
• 11:15 12:00
New Physics in b → c τ ν: Impact of Polarisation Observables and B_c → τ ν 45m
In this talk I review the status of new physics in b→cτν transitions in the EFT framework of dimension-six operators. The fit results, including the recent measurement of FL(D*), are presented for all one- and two-dimensional scenarios resulting from the tree level exchange of a single new particle. Particular emphasis is put on the constraint from the Bc→τν decay rate. I introduce a sum rule for the branching ratios of B→Dτν, B→D*τν and Λb→Λc τν which holds for any NP contribution to the Wilson coefficients and predicts an enhancement of the latter decay w.r.t. the Standard Model. I also discuss correlations between the polarisation observables in B→Dτν, B→D*τν and their model-discriminating prospects. The talk is based on the results published in https://arxiv.org/abs/1811.09603.
Speaker: Monika Blanke
• 14:00 14:45
Matrix elements for exclusive b→clν processes 45m
Speaker: Marzia Bordone
• Friday, 1 February
• 10:30 11:15
Dark sector and ALPs @ Belle-II 45m
Speaker: Giacomo De Pietro
• 11:15 12:00
New axion searches at flavour factories 45m
New particles in the ~ 1-100 GeV range that couple to gluons and photons are well motivated by frameworks addressing both the hierarchy problem and Dark Matter (e.g. the SUSY R-axion) and by "heavy axion" solutions to the strong CP problem. After reviewing these motivations, I will discuss how vast regions of parameter space are left unexplored by current collider searches. I will then propose a program of new searches for these particles, with particular emphasis on LHCb and Belle-II.
Speaker: Filippo Sala