Search

Experimental High Energy Physics has entered an era of precision measurements. However, measurements of many of the accessible processes assume that the final states’ underlying kinematic distribution is the same as the Standard Model prediction. This assumption introduces an implicit model-dependency into the measurement, rendering the reinterpretation of the experimental analysis complicated without reanalysing the underlying data. We present a novel reweighting method in order to perform reinterpretation of particle physics measurements. It makes use of reweighting the Standard Model templates according to kinematic signal distributions of alternative theoretical models, prior to performing the statistical analysis. The generality of this method allows us to perform statistical inference in the space of theoretical parameters, assuming different kinematic distributions, according to a beyond Standard Model prediction. We implement our method as an extension to the pyhf software and interface it with the EOS software, which allows us to perform flavor physics phenomenology studies. Furthermore, we argue that, beyond the pyhf or HistFactory likelihood specification, only minimal information is necessary to make a likelihood model-agnostic and hence easily reinterpretable. We showcase that publishing such likelihoods is crucial for a full exploitation of experimental results. [ABSTRACT FROM AUTHOR]

We study the inclusive and exclusive cross sections of e + e - → hadrons for center-of-mass energies between 3.70 and 3.83 GeV to infer the mass, width, and couplings of the ψ (3770) resonance. By using a coupled-channel K-matrix approach, we setup our analysis to respect unitarity and the analyticity properties of the underlying scattering amplitudes. We fit several models to the full dataset and identify our nominal results through a statistical model comparison. We find that, accounting for the interplay between the ψ (2 S) and the ψ (3770) , no further pole is required to describe the ψ (3770) line shape. In particular we derive from the pole location M ψ (3770) = 3778.8 ± 0.3 MeV and Γ ψ (3770) = 25.0 ± 0.5 MeV . Moreover, we find the decay to D + D - and D 0 D ¯ 0 to be consistent with isospin symmetry and derive an upper bound on the branching ratio B (ψ (3770) → non- D D ¯) < 6 % at 90 % probability. [ABSTRACT FROM AUTHOR]

Studying potential BSM effects at the precision frontier requires accurate transfer of information from low-energy measurements to high-energy BSM models. We propose to use normalising flows to construct likelihood functions that achieve this transfer. Likelihood functions constructed in this way provide the means to generate additional samples and admit a "trivial" goodness-of-fit test in form of a χ 2 test statistic. Here, we study a particular form of normalising flow, apply it to a multi-modal and non-Gaussian example, and quantify the accuracy of the likelihood function and its test statistic. [ABSTRACT FROM AUTHOR]

We provide updated predictions for the hadronic decays B ¯ s 0 → D s (∗) + π - and B ¯ 0 → D (∗) + K - . They are based on O (α s 2) results for the QCD factorization amplitudes at leading power and on recent results for the B ¯ (s) → D (s) (∗) form factors up to order O (Λ QCD 2 / m c 2) in the heavy-quark expansion. We give quantitative estimates of the matrix elements entering the hadronic decay amplitudes at order O (Λ QCD / m b) for the first time. Our results are very precise, and uncover a substantial discrepancy between the theory predictions and the experimental measurements. We explore two possibilities for this discrepancy: non-factorizable contributions larger than predicted by the QCD factorization power counting, and contributions beyond the Standard Model. We determine the f s / f d fragmentation fraction for the CDF, D0 and LHCb experiments for both scenarios. [ABSTRACT FROM AUTHOR]

We carry out a comprehensive analysis of the full set of B ¯ q → D q (∗) form factors for spectator quarks q = u , d , s within the framework of the Heavy-Quark expansion (HQE) to order O α s , 1 / m b , 1 / m c 2 . In addition to the available lattice QCD calculations we make use of two new sets of theoretical constraints: we produce for the first time numerical predictions for the full set of B ¯ s → D s (∗) form factors using Light-Cone sum rules with B s -meson distribution amplitudes. Furthermore, we reassess the QCD three-point sum rule results for the Isgur-Wise functions entering all our form factors for both q = u , d and q = s spectator quarks. These additional constraints allow us to go beyond the commonly used assumption of S U (3) F symmetry for the B ¯ s → D s (∗) form factors, especially in the unitarity constraints which we impose throughout our analysis. We find the coefficients of the IW functions emerging at O 1 / m c 2 to be consistent with the naive O 1 expectation, indicating a good convergence of the HQE. While we do not find significant SU(3) breaking, the explicit treatment of q = s as compared to a simple symmetry assumption renders the unitarity constraints more effective. We find that the (pseudo)scalar bounds are saturated to a large degree, which affects our theory predictions. We analyze the phenomenological consequences of our improved form factors by extracting | V cb | from B ¯ → D (∗) ℓ ν decays and producing theoretical predictions for the lepton-flavour universality ratios R(D), R (D ∗) , R (D s) and R (D s ∗) , as well as the τ - and D q ∗ polarization fractions for the B ¯ q → D q (∗) τ ν modes. [ABSTRACT FROM AUTHOR]

We carry out an analysis of the full set of ten B ¯ → D (∗) form factors within the framework of the Heavy-Quark Expansion (HQE) to order O α s , 1 / m b , 1 / m c 2 , both with and without the use of experimental data. This becomes possible due to a recent calculation of these form factors at and beyond the maximal physical recoil using QCD light-cone sum rules, in combination with constraints from lattice QCD, QCD three-point sum rules and unitarity. We find good agreement amongst the various theoretical results, as well as between the theoretical results and the kinematical distributions in B ¯ → D (∗) { e - , μ - } ν ¯ measurements. The coefficients entering at the 1 / m c 2 level are found to be of O (1) , indicating convergence of the HQE. The phenomenological implications of our study include an updated exclusive determination of | V cb | in the HQE, which is compatible with both the exclusive determination using the BGL parametrization and with the inclusive determination. We also revisit predictions for the lepton-flavour universality ratios R D (∗) , the τ polarization observables P τ D (∗) , and the longitudinal polarization fraction F L . Posterior samples for the HQE parameters are provided as ancillary files, allowing for their use in subsequent studies. [ABSTRACT FROM AUTHOR]

We discuss a novel approach to systematically determine the dominant long-distance contribution to B→K∗ℓℓ decays in the kinematic region where the dilepton invariant mass is below the open charm threshold. This approach provides the most consistent and reliable determination to date and can be used to compute Standard Model predictions for all observables of interest, including the kinematic region where the dilepton invariant mass lies between the J/ψ and the ψ(2S) resonances. We illustrate the power of our results by performing a New Physics fit to the Wilson coefficient C9. This approach is systematically improvable from theoretical and experimental sides, and applies to other decay modes of the type B→Vℓℓ, B→Pℓℓ and B→Vγ. [ABSTRACT FROM AUTHOR]