Search

In light of new data we present an updated phenomenological analysis of the simplified U 1 -leptoquark model addressing charged-current B -meson anomalies. The analysis shows a good compatibility of low-energy data (dominated by the lepton flavor universality ratios R D and R D ∗ ) with the high-energy constraints posed by p p → τ τ ¯ Drell-Yan data. We also show that present data are well compatible with a framework where the leptoquark couples with similar strength to both left- and right-handed third-generation fermions, a scenario that is well-motivated from a model building perspective. We find that the high-energy implications of this setup will be probed at the 95% confidence level in the high-luminosity phase of the LHC., (© The Author(s) 2023.)

We discuss the possibility of performing precise tests of μ / e universality in B → π ℓ + ℓ - decays. We show that in wide regions of the dilepton invariant mass spectrum the ratio between muonic and electronic decay widths can be predicted with high accuracy, both within and beyond the Standard Model. We present numerical expressions which can be used to extract precise information on short-distance dynamics if a deviation from universality is observed in the data., (© The Author(s) 2021.)

We propose improved lepton flavor universality (LFU) ratios in semileptonic P → V ℓ ν ¯ decays, when comparing μ and τ modes, that minimize the theoretical form-factor uncertainties. These optimized ratios are obtained with simple cuts or reweighting of the dilepton mass distributions, which imply a minimum loss of signal on the rare tauonic modes while maximizing the cancellation of theoretical uncertainties among the two modes. We illustrate the usefulness of these observables in B c → J / ψ , B c → ψ ( 2 S ) , B → D ∗ and B s → D s ∗ transitions, showing that in all cases we can reach O ( 1 % ) uncertainties on the SM predictions of the improved LFU ratios employing conservative form-factor uncertainties., (© The Author(s) 2020.)

We analyse the sensitivity of quark flavour-changing observables to the MSSM, in a regime of heavy superpartners. We analyse four distinct and motivated frameworks characterising the structure of the soft-breaking terms by means of approximate flavour symmetries. We show that a set of six low-energy observables with realistic chances of improvement in the near future, namely Δ M s , d , ϵ K , ϵ K ' / ϵ K , B ( K → π ν ν ¯ ) , and the phase of D - D ¯ mixing, could play a very important role in characterising these frameworks for superpartner masses up to O ( 100 )  TeV. We show that these observables remain very interesting even in a long-term perspective, i.e. even taking into account the direct mass reach of the most ambitious future high-energy colliders., (© The Author(s) 2020.)

We investigate the possibility of indirectly constraining the B + → K + τ + τ - decay rate using precise data on the B + → K + μ + μ - dimuon spectrum. To this end, we estimate the distortion of the spectrum induced by the B + → K + τ + τ - → K + μ + μ - re-scattering process, and propose a method to simultaneously constrain this (non-standard) contribution and the long-distance effects associated to hadronic intermediate states. The latter are constrained using the analytic properties of the amplitude combined with data and perturbative calculations. Finally, we estimate the sensitivity expected at the LHCb experiment with present and future datasets. We find that constraints on the branching fraction of O ( 10 - 3 ) , competitive with current direct bounds, can be achieved with the current dataset, while bounds of O ( 10 - 4 ) could be obtained with the LHCb upgrade-II luminosity., (© The Author(s) 2020.)

We perform a likelihood analysis of the minimal anomaly-mediated supersymmetry-breaking (mAMSB) model using constraints from cosmology and accelerator experiments. We find that either a wino-like or a Higgsino-like neutralino LSP, [Formula: see text], may provide the cold dark matter (DM), both with similar likelihoods. The upper limit on the DM density from Planck and other experiments enforces [Formula: see text] after the inclusion of Sommerfeld enhancement in its annihilations. If most of the cold DM density is provided by the [Formula: see text], the measured value of the Higgs mass favours a limited range of [Formula: see text] (and also for [Formula: see text] if [Formula: see text]) but the scalar mass [Formula: see text] is poorly constrained. In the wino-LSP case, [Formula: see text] is constrained to about [Formula: see text] and [Formula: see text] to [Formula: see text], whereas in the Higgsino-LSP case [Formula: see text] has just a lower limit [Formula: see text] ([Formula: see text]) and [Formula: see text] is constrained to [Formula: see text] in the [Formula: see text] ([Formula: see text]) scenario. In neither case can the anomalous magnetic moment of the muon, [Formula: see text], be improved significantly relative to its Standard Model (SM) value, nor do flavour measurements constrain the model significantly, and there are poor prospects for discovering supersymmetric particles at the LHC, though there are some prospects for direct DM detection. On the other hand, if the [Formula: see text] contributes only a fraction of the cold DM density, future LHC [Formula: see text]-based searches for gluinos, squarks and heavier chargino and neutralino states as well as disappearing track searches in the wino-like LSP region will be relevant, and interference effects enable [Formula: see text] to agree with the data better than in the SM in the case of wino-like DM with [Formula: see text].

We perform a likelihood analysis of the constraints from accelerator experiments and astrophysical observations on supersymmetric (SUSY) models with SU(5) boundary conditions on soft SUSY-breaking parameters at the GUT scale. The parameter space of the models studied has seven parameters: a universal gaugino mass [Formula: see text], distinct masses for the scalar partners of matter fermions in five- and ten-dimensional representations of SU(5), [Formula: see text] and [Formula: see text], and for the [Formula: see text] and [Formula: see text] Higgs representations [Formula: see text] and [Formula: see text], a universal trilinear soft SUSY-breaking parameter [Formula: see text], and the ratio of Higgs vevs [Formula: see text]. In addition to previous constraints from direct sparticle searches, low-energy and flavour observables, we incorporate constraints based on preliminary results from 13 TeV LHC searches for jets + [Formula: see text] events and long-lived particles, as well as the latest PandaX-II and LUX searches for direct Dark Matter detection. In addition to previously identified mechanisms for bringing the supersymmetric relic density into the range allowed by cosmology, we identify a novel [Formula: see text] coannihilation mechanism that appears in the supersymmetric SU(5) GUT model and discuss the role of [Formula: see text] coannihilation. We find complementarity between the prospects for direct Dark Matter detection and SUSY searches at the LHC.

Different mechanisms operate in various regions of the MSSM parameter space to bring the relic density of the lightest neutralino, [Formula: see text], assumed here to be the lightest SUSY particle (LSP) and thus the dark matter (DM) particle, into the range allowed by astrophysics and cosmology. These mechanisms include coannihilation with some nearly degenerate next-to-lightest supersymmetric particle such as the lighter stau [Formula: see text], stop [Formula: see text] or chargino [Formula: see text], resonant annihilation via direct-channel heavy Higgs bosons H  /  A , the light Higgs boson h or the Z boson, and enhanced annihilation via a larger Higgsino component of the LSP in the focus-point region. These mechanisms typically select lower-dimensional subspaces in MSSM scenarios such as the CMSSM, NUHM1, NUHM2, and pMSSM10. We analyze how future LHC and direct DM searches can complement each other in the exploration of the different DM mechanisms within these scenarios. We find that the [Formula: see text] coannihilation regions of the CMSSM, NUHM1, NUHM2 can largely be explored at the LHC via searches for [Formula: see text] events and long-lived charged particles, whereas their H  /  A funnel, focus-point and [Formula: see text] coannihilation regions can largely be explored by the LZ and Darwin DM direct detection experiments. We find that the dominant DM mechanism in our pMSSM10 analysis is [Formula: see text] coannihilation: parts of its parameter space can be explored by the LHC, and a larger portion by future direct DM searches.

We present a frequentist analysis of the parameter space of the pMSSM10, in which the following ten soft SUSY-breaking parameters are specified independently at the mean scalar top mass scale [Formula: see text]: the gaugino masses [Formula: see text], the first-and second-generation squark masses [Formula: see text], the third-generation squark mass [Formula: see text], a common slepton mass [Formula: see text] and a common trilinear mixing parameter A , as well as the Higgs mixing parameter [Formula: see text], the pseudoscalar Higgs mass [Formula: see text] and [Formula: see text], the ratio of the two Higgs vacuum expectation values. We use the MultiNest sampling algorithm with [Formula: see text]1.2 [Formula: see text] points to sample the pMSSM10 parameter space. A dedicated study shows that the sensitivities to strongly interacting sparticle masses of ATLAS and CMS searches for jets, leptons [Formula: see text][Formula: see text] signals depend only weakly on many of the other pMSSM10 parameters. With the aid of the Atom and Scorpion codes, we also implement the LHC searches for electroweakly interacting sparticles and light stops, so as to confront the pMSSM10 parameter space with all relevant SUSY searches. In addition, our analysis includes Higgs mass and rate measurements using the HiggsSignals code, SUSY Higgs exclusion bounds, the measurements of [Formula: see text] by LHCb and CMS, other B -physics observables, electroweak precision observables, the cold dark matter density and the XENON100 and LUX searches for spin-independent dark matter scattering, assuming that the cold dark matter is mainly provided by the lightest neutralino [Formula: see text]. We show that the pMSSM10 is able to provide a supersymmetric interpretation of [Formula: see text], unlike the CMSSM, NUHM1 and NUHM2. As a result, we find (omitting Higgs rates) that the minimum [Formula: see text] with 18 degrees of freedom (d.o.f.) in the pMSSM10, corresponding to a [Formula: see text] probability of 30.8 %, to be compared with [Formula: see text] in the CMSSM (NUHM1) (NUHM2). We display the one-dimensional likelihood functions for sparticle masses, and we show that they may be significantly lighter in the pMSSM10 than in the other models, e.g., the gluino may be as light as [Formula: see text]1250 [Formula: see text] at the 68 % CL, and squarks, stops, electroweak gauginos and sleptons may be much lighter than in the CMSSM, NUHM1 and NUHM2. We discuss the discovery potential of future LHC runs, [Formula: see text] colliders and direct detection experiments.

We analyze the impact of data from the full Run 1 of the LHC at 7 and 8 TeV on the CMSSM with [Formula: see text] and [Formula: see text] and the NUHM1 with [Formula: see text], incorporating the constraints imposed by other experiments such as precision electroweak measurements, flavour measurements, the cosmological density of cold dark matter and the direct search for the scattering of dark matter particles in the LUX experiment. We use the following results from the LHC experiments: ATLAS searches for events with [Formula: see text] accompanied by jets with the full 7 and 8 TeV data, the ATLAS and CMS measurements of the mass of the Higgs boson, the CMS searches for heavy neutral Higgs bosons and a combination of the LHCb and CMS measurements of [Formula: see text] and [Formula: see text]. Our results are based on samplings of the parameter spaces of the CMSSM for both [Formula: see text] and [Formula: see text] and of the NUHM1 for [Formula: see text] with 6.8[Formula: see text], 6.2[Formula: see text] and 1.6[Formula: see text] points, respectively, obtained using the MultiNest tool. The impact of the Higgs-mass constraint is assessed using FeynHiggs 2.10.0, which provides an improved prediction for the masses of the MSSM Higgs bosons in the region of heavy squark masses. It yields in general larger values of [Formula: see text] than previous versions of FeynHiggs, reducing the pressure on the CMSSM and NUHM1. We find that the global [Formula: see text] functions for the supersymmetric models vary slowly over most of the parameter spaces allowed by the Higgs-mass and the [Formula: see text] searches, with best-fit values that are comparable to the [Formula: see text] for the best Standard Model fit. We provide 95 % CL lower limits on the masses of various sparticles and assess the prospects for observing them during Run 2 of the LHC.