Ljubljana Summer School on Particle Physics and Cosmology

28 Aug 2023, 08:30 → 2 Sept 2023, 18:00 Europe/Ljubljana

Faculty for mathematics and physics

Summer school on theoretical aspects of calculations related to BSM searches at colliders (e.g. MC tools, analyses, machine learning techniques), flavour aspects of BSM and related phenomenological tools, as well as on astroparticle and cosmological imprints of BSM models.

The level of lectures is intended mostly for PhD students in high-energy physics, as well as for advanced Master students and early-stage postdoctoral researchers.

There is no participation fee (0 EUR) which includes lunches and coffee breaks. Accommodation in student dorms at reasonable prices will be provided.
 

		FAIME

BSM_in_Flavour-Tools-prerequisites.pdf

menu_mafija_eng.jpg

poster.pdf

ToolsForBSMInCosmo-instructions-class.pdf

Monday 28 August

1 Registration

2 BSM in flavor

Speaker: Admir Greljo

Greljo-BSM-flavour.pdf

10:00 Coffee Break

3 BSM in flavor

Speaker: Admir Greljo

Greljo-BSM-flavour

12:00 Lunch

https://indico.ijs.si/event/1607/attachments/1346/2060/menu_mafija_eng.jpg

4 BSM in flavor - tools

Speaker: Peter Stangl

BSM_in_Flavour-Tools-prerequisites.pdf

Download interactive slides "Ljubljana.zip" (offline version)

Launch interactive slides (online version)

peter.stangl@cern.ch

16:00 Coffee Break

5 BSM in flavor - tools

Speaker: Peter Stangl

Tuesday 29 August

6 BSM in flavor

Speaker: Admir Greljo

Greljo-BSM-flavour

10:00 Coffee

7 BSM in flavor

Speaker: Admir Greljo

Greljo-BSM-flavour

12:00 Lunch

8 BSM at highPT

Speaker: Francesco Riva

16:00 Coffee Break

9 BSM at highPT

Speaker: Francesco Riva

Poster session: Poster session and reception

10 LHC tau-pair production constraints on $a_τ$ and $d_τ$

We point out that relevant constraints on the anomalous magnetic ($a_τ$) and electric ($d_τ$) moment of the tau lepton can be derived from tau-pair production measurements performed at the LHC. Our conclusion is based on the observation that the leading relative deviations from the Standard Model prediction for $pp \to τ^+ τ^−$ due to $a_τ$ and $d_τ$ are enhanced at high energies. Less precise measurements at hadron colliders can therefore offer the same or better sensitivity to new physics with respect to high-precision low-energy measurements performed at lepton machines. We derive bounds on $a_τ$ and $d_τ$ using the full LHC Run II data set on tau-pair production and compare our findings with the current best limits on the tau anomalous moments.

Speaker: Joachim Weiss

11 The shift-invariant orders of an ALP

Usually, effective field theories (EFTs) for axion-like particles (ALPs) are built assuming a shift symmetry for the ALP due to the global U(1) Peccei-Quinn (PQ) symmetry that is at the heart of the axion mechanism. However, it is generally believed that global symmetries, in particular axion shift symmetries, can only be approximate. Therefore, it is important to include shift-breaking interactions in the EFT description and find a clear way to implement the different power countings of the shift-conserving and shift-breaking sectors. Focusing on the flavorful effective Yukawa couplings to Standard Model fermions, I will present Jarlskog-like flavor invariants which act as order parameters for shift symmetry breaking of the axion. In this description, shift-breaking couplings are characterized in an explicit and flavor-invariant way and it is straightforward to give different power countings to the shift-conserving and shift-breaking sectors. I will discuss properties of the invariants like their CP parities, enabling us to make non-trivial connections between conservation of CP in the theory and an almost conserved shift-symmetry for the ALP. Finally, I will discuss examples of matching UV theories to the invariants and how they can be used to identify shift-breaking contributions in observables.

Speaker: Jonathan Kley (DESY)

12 An updated view on the Atomki anomalies

In view of the latest experimental results recently released by the ATOMKI collaboration, we critically re-examine the possible theoretical interpretation of the observed anomalies in terms of a new BSM boson X with mass ∼ 17 MeV. Employing a multipole expansion method, we estimate the range of values of the nucleon couplings to the new light state in order to match the experimental observations. Our conclusions identify the axial vector state as the most promising candidate, while other spin/parity assignments seem disfavored for a combined explanation.

Speaker: Claudio Toni (Università degli studi di Roma La Sapienza)

13 Investigating new physics in $\tau-\mu$ sector via LFU ratios $R_K^{\tau \mu}$ and $R_{K^*}^{\tau \mu}$

We explore the potential of the ratios $R^{\tau \mu}$ in the decays $B \to K \ell \ell$ and $B \to K^* \ell \ell$ ($\ell=\mu,\tau$) as a means to probe new physics effects within the $\tau-\mu$ sector.We find that these ratios deviate from their SM predictions even for universal couplings. This indicates that the observed deviation of these ratios from their SM predictions alone is insufficient to definitively establish the underlying nature of new physics. For this, we need to compare the allowed range of $R^{\tau \mu}$ for a class of solutions with only universal couplings to leptons and solutions having both universal and non-universal components. By comparing the predictions of $R_K^{\tau \mu}$ and $R_{K^*}^{\tau \mu}$ for the two classes of solutions using the current data, we find that the distinction becomes feasible if the measured value of $R_{K^*}^{\tau \mu}$ exceeds the SM prediction.

Speaker: Ms NEETU RAJ SINGH CHUNDAWAT (Indian Institute of Technology, Jodhpur, India)

14 New tests of short-distance dynamics in $b\to s \bar{\ell} \ell$ decays

The rare $B \to K^{(*)} \bar{\ell} \ell$ decays exhibit a long-standing tension with Standard Model (SM) predictions, which can be attributed to a lepton-universal short-distance $b \to s \bar{\ell} \ell$ interaction.
We present two novel methods to disentangle this effect from long-distance dynamics: one based on the determination of the inclusive $b \to s \bar{\ell} \ell$ rate at high dilepton invariant mass ($q^2\geq 15~{\rm GeV}^2$), the other based on the analysis of the $q^2$ spectrum of the exclusive mode $B \to K \bar{\ell} \ell$ (in the entire $q^2$ range).

Using the first method, we show that the SM prediction for the inclusive $b \to s \bar{\ell} \ell$ rate at high dilepton invariant mass is in good agreement with the result obtained summing the SM predictions for one- and two-body modes ($K$, $K^*$, $K\pi$). This observation allows us to perform a direct comparison of the inclusive $b \to s \bar{\ell} \ell$ rate with data. This comparison shows a significant deficit ($\sim 2\sigma$) in the data, fully compatible with the deficit observed at low-$q^2$ on the exclusive modes. This provides independent evidence of an anomalous $b \to s \bar{\ell} \ell$ short-distance interaction, free from uncertainties on the hadronic form factors.
To test the short-distance nature of this effect we use a second method, where we analyze the exclusive $B \to K \bar{\ell} \ell$ differential branching ratio data in the entire $q^2$ region. Here, after using a dispersive parametrization of the narrow charmonia resonances, we extract the non-SM contribution to the universal Wilson coefficient $C_9$ for every bin in $q^2$. The $q^2$-independence of the result, and its compatibility with the inclusive determination, provide a consistency check of the short-distance nature of this effect.

(Based on arXiv:2305.03076)

Speaker: Arianna Tinari (University of Zürich)

15 NNLO+PS event generation for $p p \rightarrow Z h$ with contributions from electroweak SMEFT operators

The associated production of a Higgs boson, i.e. $p p \rightarrow Z h$, allows for precise measurements of the Higgs boson couplings. In particular, $Z h$ with $Z \rightarrow \ell^{+} \ell^{-}$and $h \rightarrow b \bar{b}$ is the most sensitive channel for detecting $h \rightarrow b \bar{b}$ decays at the LHC. It will be probed extensively in future LHC runs. We present a comprehensive next-to-next-toleading order plus parton shower (NNLO+PS) accurate event generator based on the MiNNLO $\mathrm{PS}$ method that allows to simulate non-standard Higgs interactions in $V h$. In particular, we extend previous work to include the effects of the relevant electroweak SM effective field theory (SMEFT) operators and anomalous Higgs couplings. The ensuing phenomenology is discussed, presenting observables where the non-standard Higgs interactions in question lead to interesting changes in the event shapes.

Speaker: Luc Schnell

Wednesday 30 August

16 BSM in flavor - tools

Speaker: Peter Stangl

10:00 Coffee Break

17 BSM in flavor - tools

Speaker: Peter Stangl

12:00 Lunch

18 BSM at highPT

Speaker: Francesco Riva

15:30 Coffee Break

19 BSM at highPT

Speaker: Francesco Riva

Thursday 31 August

20 BSM at highPT - tools

Speaker: Darius Faroughy

BSM_course_2023

10:00 Coffee Break

21 BSM at highPT - tools

Speaker: Darius Faroughy

BSM_course_2023

12:00 Lunch

22 BSM in cosmo

Speaker: Andrea Tesi

15:30 Coffee Break

23 BSM in cosmo

Speaker: Andrea Tesi

19:00 School Dinner

Friday 1 September

24 BSM at highPT - tools

Speaker: Darius Faroughy

BSM_course_2023

10:00 Coffee Break

25 BSM at highPT - tools

Speaker: Darius Faroughy

BSM_course_2023

12:00 Lunch Break

26 BSM in cosmo - tools

Speaker: Andrea Tesi

Instructions

15:30 Coffee Break

27 BSM in cosmo - tools

Speaker: Andrea Tesi

Instructions

Saturday 2 September

28 Minicourse - Machine Learning

Speaker: Tilman Plehn

10:00 Coffee Break

29 Minicourse - Machine Learning

Speaker: Tilman Plehn

12:00 Lunch

30 Minicourse - Machine Learning - tools

Speaker: Luigi Favaro

Material for the ML hands-on session

ml_tools_requirements.pdf

15:30 Coffee Break

31 Minicourse - Machine Learning - tools

Speaker: Luigi Favaro

Material for the ML hands-on session