
Abbas, G., Celis, A., Li, X. Q., Lu, J., & Pich, A. (2015). Flavourchanging top decays in the aligned twoHiggsdoublet model. J. High Energy Phys., 06(6), 005–26pp.
Abstract: We perform a complete oneloop computation of the twobody flavourchanging top decays t > ch and t > cV (V = gamma, Z), within the aligned twoHiggsdoublet model. We evaluate the impact of the model parameters on the associated branching ratios, taking into account constraints from flavour data and measurements of the Higgs properties. Assuming that the 125 GeV Higgs corresponds to the lightest CPeven scalar of the CPconserving aligned twoHiggsdoublet model, we find that the rates for such flavourchanging top decays lie below the expected sensitivity of the future highluminosity phase of the LHC. Measurements of the Higgs signal strength in the diphoton channel are found to play an important role in limiting the size of the t > ch decay rate when the charged scalar of the model is light.



Albaladejo, M., Daub, J. T., Hanhart, C., Kubis, B., & Moussallamd, B. (2017). How to employ (B)overbar(d)(0) > J/psi(pi eta, (K)overbarK) decays to extract information on pi eta scattering. J. High Energy Phys., 04(4), 010–28pp.
Abstract: We demonstrate that dispersion theory allows one to deduce crucial information on pi eta scattering from the finalstate interactions of the light mesons visible in the spectral distributions of the decays (B) over bar (0)(d) > J/psi(pi(0)eta, K+K, K0 (K) over bar (0)). Thus highquality measurements of these differential observables are highly desired. The corresponding rates are predicted to be of the same order of magnitude as those for (B) over bar (0)(d) > J/psi pi(+)pi() measured recently at LHCb, letting the corresponding measurement appear feasible.



Belanger, G., Bharucha, A., Fuks, B., Goudelis, A., Heisig, J., Jueid, A., et al. (2022). Leptoquark manoeuvres in the dark: a simultaneous solution of the dark matter problem and the RD(*) anomalies. J. High Energy Phys., 02(2), 042–58pp.
Abstract: The measured branching fractions of Bmesons into leptonic final states derived by the LHCb, Belle and BaBar collaborations hint towards the breakdown of lepton flavour universality. In this work we take at face value the socalled RD(()*()) observables that are defined as the ratios of neutral Bmeson chargedcurrent decays into a D(*())meson, a charged lepton and a neutrino final state in the tau and light lepton channels. A wellstudied and simple solution to this charged current anomaly is to introduce a scalar leptoquark S1 that couples to the second and third generation of fermions. We investigate how S1 can also serve as a mediator between the Standard Model and a dark sector. We study this scenario in detail and estimate the constraints arising from collider searches for leptoquarks, collider searches for missing energy signals, direct detection experiments and the dark matter relic abundance. We stress that the production of a pair of leptoquarks that decays into different final states (i.e. the commonly called “mixed” channels) provides critical information for identifying the underlying dynamics, and we exemplify this by studying the t tau b nu and the resonant S1 plus missing energy channels. We find that direct detection data provides nonnegligible constraints on the leptoquark coupling to the dark sector, which in turn affects the relic abundance. We also show that the correct relic abundance can not only arise via standard freezeout, but also through conversiondriven freezeout. We illustrate the rich phenomenology of the model with a few selected benchmark points, providing a broad stroke of the interesting connection between lepton flavour universality violation and dark matter.



Bernardoni, F., Hernandez, P., & Necco, S. (2010). Heavylight mesons in the epsilonregime. J. High Energy Phys., 01(1), 070–30pp.
Abstract: We study the finitesize scaling of heavylight mesons in the static limit. We compute twopoint functions of chiral current densities as well as pseudoscalar densities in the epsilonregime of heavy meson Chiral Perturbation Theory (HMChPT). As expected, finite volume dependence turns out to be significant in this regime and can be predicted in the effective theory in terms of the infinitevolume lowenergy couplings. These results might be relevant for extraction of heavymeson properties from lattice simulations.



Della Morte, M., Dooling, S., Heitger, J., Hesse, D., & Simma, H. (2014). Matching of heavylight flavour currents between HQET at order 1/m and QCD: I. Strategy and treelevel study. J. High Energy Phys., 05(5), 060–31pp.
Abstract: We present a strategy how to match the full set of components of the heavylight axial and vector currents in Heavy Quark Effective Theory (HQET), up to and including 1/m (h) corrections, to QCD. While the ultimate goal is to apply these matching conditions nonperturbatively, in this study we first have implemented them at treelevel, in order to find good choices of the matching observables with small contributions. They can later be employed in the nonperturbative matching procedure which is a crucial part of precision HQET computations of semileptonic decay form factors in lattice QCD.



Durieux, G., Perello, M., Vos, M., & Zhang, C. (2018). Global and optimal probes for the topquark effective field theory at future lepton colliders. J. High Energy Phys., 10(10), 168–68pp.
Abstract: We study the sensitivity to physics beyond the standard model of precise topquark pair production measurements at future lepton colliders. A global effectivefieldtheory approach is employed, including all ten dimensionsix operators of the Warsaw basis which involve a topquark and give rise to treelevel amplitudes that interfere with standardmodel e+ett ones in the limit of vanishing bquark mass. Fourfermion and CPviolating contributions are taken into account. Circularcollider, ILC and CLIClike benchmark run scenarios are examined. We compare the constraining power of various observables to a set of statistically optimal ones which maximally exploit the information contained in the fully differential bW+ distribution. The enhanced sensitivity gained on the linear contributions of dimensionsix operators leads to bounds that are insensitive to quadratic ones. Even with statistically optimal observables, two centreofmass energies are required for constraining simultaneously two and fourfermion operators. The impact of the centreofmass energy lever arm is discussed, that of beam polarization as well. A realistic estimate of the precision that can be achieved in ILC and CLIClike operating scenarios yields individual limits on the electroweak couplings of the top quark that are one to three orders of magnitude better than constraints set with Tevatron and LHC run I data, and three to two hundred times better than the most optimistic projections made for the highluminosity phase of the LHC. Clean global constraints can moreover be obtained at lepton colliders, robustly covering the multidimensional effectivefieldtheory space with minimal model dependence.



Hoang, A. H., RuizFemenia, P., & Stahlhofen, M. (2012). Renormalization group improved bottom mass from (gamma) sum rules at NNLL order. J. High Energy Phys., 10(10), 188–30pp.
Abstract: We determine the bottom quark mass from nonrelativistic largen gamma sum rules with renormalization group improvement at nexttonexttoleading logarithmic order. We compute the theoretical moments within the vNRQCD formalism and account for the summation of powers of the Coulomb singularities as well as of logarithmic terms proportional to powers of alpha(s) ln(n). The renormalization group improvement leads to a substantial stabilization of the theoretical moments compared to previous fixedorder analyses, which did not account for the systematic treatment of the logarithmic alpha(s) ln(n) terms, and allows for reliable single moment fits. For the current world average of the strong coupling (alpha(s) (MZ) = 0.1183 +/ 0.0010) we obtain Mb(1S) = 4.755 +/ 0.057(pert) +/ 0.009 alpha(s) +/ 0.003(exp) GeV for the bottom 1S mass and (m) over bar (b) ((m) over bar (b)) = 4.235 +/ 0.055(pert) +/ 0.003(exp) GeV for the bottom (MS) over bar mass, where we have quoted the perturbative error and the uncertainties from the strong coupling and the experimental data.



Kuhn, J. H., & Rodrigo, G. (2012). Charge asymmetries of top quarks at hadron colliders revisited. J. High Energy Phys., 01(1), 063–25pp.
Abstract: A sizeable difference in the differential production cross section of topcompared to antitopquark production, denoted charge asymittetm has been observed at the Tevatron. The experimental results seem to exceed the theory predictions based on the Standard Model by a significant amount and have triggered a large number of suggestions for “new physics'. In the present paper the Standard Model predictions for Tevatron and LHe experiments are revisited. This includes a reanalysis of electromagnetic as well as weak corrections, leading to a shift of the asymmetry by roughly a factor 1.1 when compared to the results of the first papers on this subject. The impact of cuts on the transverse momentum of the topantitop system is studied. Restricting the it system to a transverse momentum less than 20 GeV leads to an enhancement of the asymmetries by factors between 1.3 and 1.5, indicating the importance of an improved understanding of the ttmomentum distribution. Predictions for similar measurements at the LHC are presented, demonstrating the sensitivity of the large rapidity region bot ti to the Standard Model contribution and effects from ”new physics".

