Abstract 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 $$f_+(0)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>f</mml:mi> <mml:mo>+</mml:mo> </mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>0</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math> arising in the semileptonic $$K \rightarrow \pi $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>K</mml:mi> <mml:mo>→</mml:mo> <mml:mi>π</mml:mi> </mml:mrow> </mml:math> transition at zero momentum transfer, as well as the decay constant ratio $$f_K/f_\pi $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>f</mml:mi> <mml:mi>K</mml:mi> </mml:msub> <mml:mo>/</mml:mo> <mml:msub> <mml:mi>f</mml:mi> <mml:mi>π</mml:mi> </mml:msub> </mml:mrow> </mml:math> and its consequences for the CKM matrix elements $$V_{us}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>V</mml:mi> <mml:mrow> <mml:mi>us</mml:mi> </mml:mrow> </mml:msub> </mml:math> and $$V_{ud}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>V</mml:mi> <mml:mrow> <mml:mi>ud</mml:mi> </mml:mrow> </mml:msub> </mml:math> . Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of $$SU(2)_L\times SU(2)_R$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>S</mml:mi> <mml:mi>U</mml:mi> <mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>2</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mi>L</mml:mi> </mml:msub> <mml:mo>×</mml:mo> <mml:mi>S</mml:mi> <mml:mi>U</mml:mi> <mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>2</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mi>R</mml:mi> </mml:msub> </mml:mrow> </mml:math> and $$SU(3)_L\times SU(3)_R$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>S</mml:mi> <mml:mi>U</mml:mi> <mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>3</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mi>L</mml:mi> </mml:msub> <mml:mo>×</mml:mo> <mml:mi>S</mml:mi> <mml:mi>U</mml:mi> <mml:msub> <mml:mrow> <mml:mo>(</mml:mo> <mml:mn>3</mml:mn> <mml:mo>)</mml:mo> </mml:mrow> <mml:mi>R</mml:mi> </mml:msub> </mml:mrow> </mml:math> Chiral Perturbation Theory. We review the determination of the $$B_K$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>B</mml:mi> <mml:mi>K</mml:mi> </mml:msub> </mml:math> 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 $$m_c$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>m</mml:mi> <mml:mi>c</mml:mi> </mml:msub> </mml:math> and $$m_b$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>m</mml:mi> <mml:mi>b</mml:mi> </mml:msub> </mml:math> as well as those for the decay constants, form factors, and mixing parameters of charmed and bottom mesons and baryons. 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 $$\alpha _s$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>α</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> . We consider nucleon matrix elements, and review the determinations of the axial, scalar and tensor bilinears, both isovector and flavor diagonal. Finally, in this review we have added a new section reviewing determinations of scale-setting quantities. 

FLAG Review 2021

We revisit the possibilities of accommodating the experimental indications of the lepton flavor universality violation in $b$-hadron decays in the minimal scenarios in which the Standard Model is extended by the presence of a single $\mathcal{O}(1\text{ }\text{ }\mathrm{TeV})$ leptoquark state. To do so we combine the most recent low energy flavor physics constraints, including ${R}_{{K}^{(*)}}^{\mathrm{exp}}$ and ${R}_{{D}^{(*)}}^{\mathrm{exp}}$, and combine them with the bounds on the leptoquark masses and their couplings to quarks and leptons as inferred from the direct searches at the LHC and the studies of the large ${p}_{T}$ tails of the $pp\ensuremath{\rightarrow}\ensuremath{\ell}\ensuremath{\ell}$ differential cross section. We find that none of the scalar leptoquarks of ${m}_{\mathrm{LQ}}\ensuremath{\simeq}1\textdiv{}2\text{ }\text{ }\mathrm{TeV}$ can accommodate the $B$-anomalies alone. Only the vector leptoquark, known as ${U}_{1}$, can provide a viable solution which, in the minimal setup, provides an interesting prediction, i.e., a lower bound to the lepton flavor violating $b\ensuremath{\rightarrow}s{\ensuremath{\mu}}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\tau}}^{\ensuremath{\mp}}$ decay modes, such as $\mathcal{B}(B\ensuremath{\rightarrow}K\ensuremath{\mu}\ensuremath{\tau})\ensuremath{\gtrsim}0.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$.

Single leptoquark solutions to the B -physics anomalies


 High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF’s physics potential.

https://iopscience.iop.org/article/10.1088/1361-6471/ac865e/pdf

The Forward Physics Facility at the High-Luminosity LHC

Low energy SUSY confronted with new measurements of W-boson mass and muon g-2.

Recently, both ATLAS and CMS measured the decay $h\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, finding a signal strength with respect to the standard model expectation of $1.2\ifmmode\pm\else\textpm\fi{}0.6$ and ${1.19}_{\ensuremath{-}0.39\ensuremath{-}0.16}^{+0.41+0.17}$, respectively. This provides, for the first time, evidence that the standard model Higgs couples to second generation fermions. This measurement is particularly interesting in the context of the intriguing hints for lepton flavor universality violation, accumulated within recent years, as new physics explanations could also be tested in the $h\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ decay mode. Leptoquarks are prime candidates to account for the flavor anomalies. In particular, they can provide the necessary chiral enhancement (by a factor ${m}_{t}/{m}_{\ensuremath{\mu}}$) to address ${a}_{\ensuremath{\mu}}$ with tera-electron-volt scale new physics. In this Letter we point out that such explanations of ${a}_{\ensuremath{\mu}}$ also lead to enhanced effects in $h\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and we examine the correlations between $h\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${a}_{\ensuremath{\mu}}$ within leptoquark models. We find that the effect in the branching ratio of $h\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ ranges from several percent up to a factor of 3, if one aims at accounting for ${a}_{\ensuremath{\mu}}$ at the $2\ensuremath{\sigma}$ level. Hence, the new ATLAS and CMS Collaboration measurements already provide important constraints on the parameter space, rule out specific ${a}_{\ensuremath{\mu}}$ explanations, and will be very important to test the flavor anomalies in the future.

/pdf/correlating-h-m-m-to-the-anomalous-magnetic-moment-of-the-522c780ef8.pdf

Correlating h→μ^{+}μ^{-} to the Anomalous Magnetic Moment of the Muon via Leptoquarks.

This paper reports world averages of measurements of b -hadron, c -hadron, and -lepton properties obtained by the Heavy Flavour Averaging Group using results available through September 2018. In rare cases, significant results obtained several months later are also used. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters,  violation parameters, parameters of semileptonic decays, and Cabibbo–Kobayashi–Maskawa matrix elements.

H.-L. Ma

Papers

Averages of b-hadron, c-hadron, and $$\tau $$-lepton properties as of 2018: Heavy Flavor Averaging Group (HFLAV)