We review lattice results related to pion, kaon, D-meson, B-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More specifically, we report on the determination of the light-quark masses, the form factor $f_+(0)$ arising in the semileptonic $K \rightarrow \pi $ transition at zero momentum transfer, as well as the decay constant ratio $f_K/f_\pi $ and its consequences for the CKM matrix elements $V_{us}$ and $V_{ud}$. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of $SU(2)_L\times SU(2)_R$ and $SU(3)_L\times SU(3)_R$ Chiral Perturbation Theory. We review the determination of the $B_K$ parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. For the heavy-quark sector, we provide results for $m_c$ and $m_b$ as well as those for D- and B-meson decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. We review the status of lattice determinations of the strong coupling constant $\alpha _s$. Finally, in this review we have added a new section reviewing results for nucleon matrix elements of the axial, scalar and tensor bilinears, both isovector and flavor diagonal.

FLAG Review 2019

HEPfit is a flexible open-source tool which, given the Standard Model or any of its extensions, allows to (i) fit the model parameters to a given set of experimental observables; (ii) obtain predictions for observables. HEPfit can be used either in Monte Carlo mode, to perform a Bayesian Markov Chain Monte Carlo analysis of a given model, or as a library, to obtain predictions of observables for a given point in the parameter space of the model, allowing HEPfit to be used in any statistical framework. In the present version, around a thousand observables have been implemented in the Standard Model and in several new physics scenarios. In this paper, we describe the general structure of the code as well as models and observables implemented in the current release.

/pdf/hepfit-a-code-for-the-combination-of-indirect-and-direct-2u56e1xh80.pdf

HEPfit : a code for the combination of indirect and direct constraints on high energy physics models

Collider physics at the precision frontier

Based on recent HQET sum rule and lattice calculations we present updated Standard Model predictions for the mass differences of neutral $B$ mesons: $\Delta M_s^{\rm SM} = \left(18.4^{+0.7}_{-1.2} \right) \mbox{ps}^{-1}$ and $\Delta M_d^{\rm SM} = \left(0.533^{+0.022}_{-0.036} \right) \mbox{ps}^{-1}$ and study their impact on new physics models that address the present hints of anomalous data in $b \to s \ell \ell$ transitions. We also examine future prospects of further reducing the theory uncertainties and discuss the implications of a 2025 scenario with $\Delta M_s^\text{SM 2025} = \left(18.4 \pm 0.5\right) \mbox{ps}^{-1}$. In particular, the latter yields upper bounds $M_{Z'}\lesssim 9~\text{TeV}$ and $M_{S_3}\lesssim 30~\text{TeV}$ for the minimal $Z'$ and $S_3$ lepto-quark explanations of the $b \to s \ell \ell$ anomalies, respectively.

/pdf/delta-m-s-theory-precision-confronts-flavour-anomalies-55hn46hai7.pdf

$\Delta M_s$ theory precision confronts flavour anomalies.

wilson is a Python library for matching and running Wilson coefficients of higher-dimensional operators beyond the Standard Model. Provided with the numerical values of the Wilson coefficients at a high new physics scale, it automatically performs the renormalization group evolution within the Standard Model effective field theory (SMEFT), matching onto the weak effective theory (WET) at the electroweak scale, and QCD/QED renormalization group evolution below the electroweak scale down to hadronic scales relevant for low-energy precision tests. The matching and running encompasses the complete set of dimension-six operators in both SMEFT and WET. The program builds on the Wilson coefficient exchange format (WCxf) and can thus be easily combined with a number of existing public codes.

/pdf/a-python-package-for-the-running-and-matching-of-wilson-pxivflk1nj.pdf

a Python package for the running and matching of Wilson coefficients above and below the electroweak scale

Version 3 of RunDec and CRunDec

An important ingredient for the calculation of Higgs boson properties in the infinite top quark mass limit is the knowledge of the effective coupling between the Higgs bosons and gluons, i.e. the Wilson coefficients CH and CHH for one and two Higgs bosons, respectively. In this work we calculate for the first time CHH to four loops in a direct, diagrammatic way, discussing in detail all issues arising due to the renormalization of operator products. Furthermore, we also calculate the Wilson coefficient CH for the coupling of a single Higgs boson to gluons as well as all four loop decoupling relations in QCD with general SU(Nc) colour factors. The latter are related to CH and CHH via low-energy theorems, which are used to obtain five-loop results for the Wilson coefficients.

/pdf/wilson-coefficients-for-higgs-boson-production-and-3ebrlhj7ft.pdf

Wilson coefficients for Higgs boson production and decoupling relations to $ \mathcal{O}\left({\alpha}_s^4\right) $

We compute the β functions of the three standard model gauge couplings to four-loop order in the modified minimal subtraction scheme. At this order a proper definition of γ_{5} in D=4-2e space-time dimensions is required; however, in our calculation we determine the γ_{5}-dependent terms by exploiting relations with β function coefficients at lower loop orders.

Gauge Coupling β Functions to Four-Loop Order in the Standard Model

We compute the beta functions for the three gauge couplings and the Yukawa matrices of a general two-Higgs-doublet model in the modified minimal subtraction scheme to three loops. The calculations are performed using Lorenz gauge in the unbroken phase. We discuss in detail the occurence of poles in anomalous dimensions and propose practical prescriptions to avoid them. We provide explicit results for the often used $\mathbb{Z}_2$-symmetric versions of the two-Higgs-doublet model of type I, II, X and Y. Furthermore, we provide the first independent cross-check of the three-loop Yukawa coupling beta functions of the Standard Model.

Gauge and Yukawa coupling beta functions of two-Higgs-doublet models to three-loop order

We compute the real-radiation corrections, i.e. the virtual corrections to the single real emission of a parton, to Higgs boson pair production at next-to-next-to-leading order in QCD, in an expansion for large top quark mass. We concentrate on the radiative corrections to the interference contribution from the next-to-leading order one-particle reducible and the leading order amplitudes. This is a well defined and gauge invariant subset of the full real-virtual corrections to the inclusive cross section. We obtain analytic results for all phase-space master integrals both as an expansion around the threshold and in an exact manner in terms of Goncharov polylogarithms. We demonstrate that for many applications it is sufficient to use the expanded expressions.

/pdf/real-virtual-corrections-to-higgs-boson-pair-production-at-3ppjn3jqc0.pdf

Florian Herren

Papers

Version 3 of RunDec and CRunDec

Wilson coefficients for Higgs boson production and decoupling relations to $ \mathcal{O}\left({\alpha}_s^4\right) $

Gauge Coupling β Functions to Four-Loop Order in the Standard Model

Gauge and Yukawa coupling beta functions of two-Higgs-doublet models to three-loop order

Real-virtual corrections to Higgs boson pair production at NNLO: three closed top quark loops