I recently installed the version 3.9 of Python in my computer. For the moment, I want to retain the version 3.8 alongside it (probably the best way to do it would be using virtualenvs, but I don’t have time to learn it now). Obviously, some packages needed new versions: the usual suspects numpy, scipy, matplotlib, etc. But for the rest of packages, I wanted to keep the old ones, so I don’t have to manage two versions of the same packages.

Welcome to my personal page. I will periodically post any updates here.

You can also check my Github discussion page.

How does it work?

This site is hosted in Github pages. Everything you see around here is generated from this repo. The posts are (mostly) written in Markdown, and then converted into HTML by Jekyll using the hydejack template. Comments in the posts are provided by giscus, which uses Github’s discussion system. The “Around the arXiv” posts are processed by this script, which reads arXiv’s API and escapes special characters.

Florentin Jaffredo

Abstract: We revisit the constraints on semileptonic operators derived from the mono-\(\tau\) high-\(p_T\) events in \(pp\) collisions at LHC. Like in previous studies, we obtain limits on the New Physics couplings from the CMS data much stronger than from the ATLAS data, despite a nearly equal integrated luminosity. We find that a neglected systematics on the \(\tau\) lepton reconstruction efficiency can partly explain that difference. We then provide new limits on the New Physics couplings relevant to decays based on \(b\to c\tau\bar{\nu}\) by using the recent ATLAS data with 139 \({\rm fb}^{-1}\). We also show that the inclusion of propagation of the New Physics particle can significantly worsen the bounds obtained by relying on Effective Field Theoretical treatment of New Physics.

Triparno Bandyopadhyay, Subhajit Ghosh, Tuhin S. Roy

Abstract: A light axion-like particle or an ALP not just gives rise to interesting and spectacular signals of new physics as final states in meson decays, it necessarily leaves tell-tale signatures in processes that involve standard model (SM) fields only (i.e., SM processes). These effects result in the violation of the Gell-Mann–Okubo mass relation, modified form factors, altered integrated and differential rates for various SM transitions etc. This suggests that in the presence of a low lying state, such as an ALP, extraction of masses, mixing angles, and form factors in an entirely data-driven way from meson-physics observables is a highly non-trivial exercise. However, once done correctly, these same observables may, in turn, provide important (indirect) bounds on ALP physics, which remain robust even in the limits where new physics effects conspire to weaken the bounds from direct searches. Starting with a generalized ALP-quark Lagrangian (where restrictions due to parity are removed) we demonstrate this approach by focussing on \(K^+_{\ell_3}\) decays, where we derive (indirect) bounds on ALP physics using NA48/2 data and lattice results. We also find sum rules which not just show deviations in the presence of an ALP, but also give hints towards the specific nature of the ALP physics itself.

Mikael Chala, Álvaro Díaz-Carmona, Guilherme Guedes

Abstract: We present a basis of dimension-eight Green’s functions involving Standard Model (SM) bosonic fields, consisting of 86 new operators. Rather than using algebraic identities and integration by parts, we prove the independence of these interactions in momentum space, including a discussion on evanescent bosonic operators. Our results pave the way for renormalising the SM effective field theory (SMEFT), as well as for performing matching of ultraviolet models onto the SMEFT, to higher order. To demonstrate the potential of our construction, we have implemented our basis in matchmakereft and used it to integrate out a heavy singlet scalar and a heavy quadruplet scalar up to one loop. We provide the corresponding dimension-eight Wilson coefficients. Likewise, we show how our results can be easily used to simplify cumbersome redundant Lagrangians arising, for example, from integrating out heavy fields using the path-integral approach to matching.

Jing Gao, Tobias Huber, Yao Ji, Chao Wang, Yu-Ming Wang, Yan-Bing Wei

Abstract: We investigate the subleading-power corrections to the exclusive \(B\to D \ell \nu_\ell\) form factors at \({\cal O} (\alpha_s^0)\) in the light-cone sum rules (LCSR) framework by including the two- and three-particle higher-twist contributions from the \(B\)-meson light-cone distribution amplitudes up to the twist-six accuracy, by taking into account the subleading terms in expanding the hard-collinear charm-quark propagator, and by evaluating the hadronic matrix element of the subleading effective current \(\bar q \, \gamma_{\mu} \, i \not\!\!{D}_\perp / (2 \, m_b) \, h_v\). Employing further the available leading-power results for the semileptonic \(B \to D\) form factors at the next-to-leading-logarithmic level and combining our improved LCSR predictions with the recent lattice determinations, we then carry out a comprehensive phenomenological analysis on the semi-leptonic \(B\to D \ell \nu_\ell\) decay. We extract \(|V_{cb}| = \big(40.3^{+0.9}_{-0.8} {\big |_{\rm th}}\,\, {}^{+1.4}_{-1.4} {\big |_{\rm exp}} \big) \times 10^{-3}\) (\(|V_{cb}| = \big(41.0^{+0.9}_{-0.8} {\big |_{\rm th}}\,\, {}^{+1.0}_{-1.0} {\big |_{\rm exp}} \big) \times 10^{-3}\)) using the BaBar (Belle) experimental data, and particularly obtain for the gold-plated ratio \(R(D) = 0.305 \pm 0.007\).

N Rajeev, Rupak Dutta

Abstract: The long persistent discrepancies in \(b\,\to\,s\, \ell\, \ell\) quark level transitions continue to be the ideal platform for an indirect search of new physics that lies beyond the SM. The measurements of \(R_K\), \(R_{K^*}\), \(P_5^{\prime}\), \(\mathcal{B}(B_s\, \to\, \phi\, \mu^+\,\mu^-)\) and \(\mathcal{B}(B_s\, \to\, \mu^+\,\mu^-)\) persistently deviate from the standard model expectations. Similarly, the new tests of lepton flavor universality performed using the isospin partners such as \(B^0 \, \to \, K_S^{0} \, \ell\,\ell\) and \(B^+ \, \to \, K^{+*} \, \ell\,\ell\) exhibit the same pattern of deviation in \(R_{K_S^0}\) and \(R_{K^{*+}}\) with the existing results. Motivated by these anomalies we search for the patterns of new physics in the family of flavor changing neutral decays with neutral leptons in the final state undergoing \(b \, \to \,s\, \nu \, \bar{\nu}\) quark level transitions. There are close relations between \(b\,\to\,s\, \ell\, \ell\) and \(b \, \to \,s\, \nu \, \bar{\nu}\) transitions not only in standard model but also in various beyond the standard model scenarios. For beyond the standard model physics under the \(\rm SU_L(2)\) gauge symmetry one can relate the left handed charged leptons to the neutrinos. Moreover, there are several advantages of studying \(b \, \to \,s\, \nu \, \bar{\nu}\) transitions over \(b\,\to\,s\, \ell\, \ell\) as they are free from various hadronic uncertainties beyond the form factors such as the non-factorizable corrections and photonic penguin contributions. Hence, we explore the consequences of \(b\, \to\, s\, \mu^+\, \mu^-\) anomalies on \(B \, \to \, K^{(*)} \,\nu \, \bar{\nu}\), \(B_s \to\, (\eta,\eta’) \, \nu\,\bar{\nu}\) and \(B_s \, \to \, \phi \, \nu \, \bar{\nu}\) decay observables in SMEFT platform within various 1D and 2D new physics scenarios.

Adrian Carmona, Achilleas Lazopoulos, Pablo Olgoso, Jose Santiago

Abstract: We introduce matchmakereft, a fully automated tool to compute the tree-level and one-loop matching of arbitrary models onto arbitrary effective theories. Matchmakereft performs an off-shell matching, using diagrammatic methods and the background field method when gauge theories are involved. The large redundancy inherent to the off-shell matching together with explicit gauge invariance offers a significant number of non-trivial checks of the results provided. These results are given in the physical basis but several intermediate results, including the matching in the Green basis before and after canonical normalization, are given for flexibility and the possibility of further cross-checks. As a non-trivial example we provide the complete matching in the Warsaw basis up to one loop of an extension of the Standard Model with a charge -1 vector-like lepton singlet. Matchmakereft has been built with generality, flexibility and efficiency in mind. These ingredients allow matchmakereft to have many applications beyond the matching between models and effective theories. Some of these applications include the one-loop renormalization of arbitrary theories (including the calculation of the one-loop renormalization group equations for arbitrary theories); the translation between different Green bases for a fixed effective theory or the check of (off-shell) linear independence of the operators in an effective theory. All these applications are performed in a fully automated way by matchmakereft.

Luca Di Luzio, Antonio Masiero, Paride Paradisi, Massimo Passera

Abstract: The recent measurement of the muon \(g\)-2 at Fermilab confirms the previous Brookhaven result. The leading hadronic vacuum polarization (HVP) contribution to the muon \(g\)-2 represents a crucial ingredient to establish if the Standard Model prediction differs from the experimental value. A recent lattice QCD result by the BMW collaboration shows a tension with the low-energy \(e^+e^- \to \text{hadrons}\) data which are currently used to determine the HVP contribution. We refer to this tension as the new muon \(g\)-2 puzzle. In this Letter we consider the possibility that new physics contaminates the experimental extraction of the \(e^+e^- \to \text{hadrons}\) cross-section. This scenario could, in principle, solve the new muon \(g\)-2 puzzle. However, we show that this solution is excluded by a number of experimental constraints.

T. Hurth, F. Mahmoudi, D. Martinez Santos, S. Neshatpour

Abstract: We analyse the new physics implications of theoretically clean \(b \to s\) observables in a model-independent approach and compare their coherence with the implications of other rare \(B\)-decays. A statistical comparison is done between the New Physics explanation and hadronic contributions as the source of the anomalies in angular observables of the \(B\to K^*\mu\mu\) decay. We make projections for future measurements that indicate that LHCb will be in the position to discover lepton non-universality via a single observable using the Run 3 data. The global fit of rare \(B\)-decays is given within a multidimensional fit involving all the 20 relevant Wilson coefficients.