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Register a new userPrecise predictions for $mathrm{WH}$+jet production at the LHC
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We present precise predictions for the production of a Higgs boson in association with a hadronic jet and a $mathrm{W}$ boson at hadron colliders. The behaviour of QCD corrections are studied for fiducial cross sections and distributions of the charged gauge boson and jet-related observables. The inclusive process (at least one resolved jet) and the exclusive process (exactly one resolved jet) are contrasted and discussed. The inclusion of QCD corrections up to $mathcal{O}(alpha_{text{s}}^3)$ leads to a clear stabilisation of the predictions and contributes substantially to a reduction of remaining theoretical uncertainties.
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We present the full NLO SUSY-QCD corrections to the pair production of neutralinos and charginos at the LHC in association with a jet and their matching to parton-shower programs in the framework of the POWHEG-BOX package. The code we have developed provides a SUSY Les Houches Accord interface for setting electroweak and supersymmetric input parameters. Decays of the neutralinos and charginos and parton-shower effects can be simulated with multi-purpose programs such as PYTHIA. The capabilities of the code are illustrated by phenomenological results for a parameter point in the framework of pMSSM10, compatible with present experimental limits on supersymmetry. We find that NLO-QCD corrections as well as parton-shower effects are of primary importance for the appropriate description of jet distributions.
The angular distributions of lepton pairs in the Drell-Yan process can provide rich information on the underlying QCD production mechanisms. These dynamics can be parameterised in terms of a set of frame dependent angular coefficients, $A_{i=0,ldots,7}$, which depend on the invariant mass, transverse momentum, and rapidity of the lepton pair. Motivated by recent measurements of these coefficients by ATLAS and CMS, and in particular by the apparent violation of the Lam-Tung relation $A_0-A_2=0$, we perform a precision study of the angular coefficients at $mathcal{O}(alpha_s^3)$ in perturbative QCD. We make predictions relevant for $pp$ collisions at $sqrt{s} = 8$ TeV, and perform comparisons with the available ATLAS and CMS data as well as providing predictions for a prospective measurement at LHCb. To expose the violation of the Lam-Tung relationship we propose a new observable $Delta^mathrm{LT} = 1-A_2/A_0$ that is more sensitive to the dynamics in the region where $A_0$ and $A_2$ are both small. We find that the $mathcal{O}(alpha_s^3)$ corrections have an important impact on the $p_{T,Z}$ distributions for several of the angular coefficients, and are essential to provide an adequate description of the data. The compatibility of the available ATLAS and CMS data is reassessed by performing a partial $chi^2$ test with respect to the central theoretical prediction which shows that $chi^2/N_mathrm{data}$ is significantly reduced by going from $mathcal{O}(alpha_s^2)$ to $mathcal{O}(alpha_s^3)$.
Precise predictions are provided for the production of a $mathrm{Z}$-boson and a $mathrm{b}$-jet in hadron-hadron collisions within the framework of perturbative QCD, at $mathcal{O}(alpha_s^3)$. To obtain these predictions we perform the first calculation of a hadronic scattering process involving the direct production of a flavoured-jet at next-to-next-to-leading order accuracy in massless QCD, and extend techniques to also account for the impact of finite heavy-quark mass effects. The predictions are compared to CMS data obtained in $mathrm{pp}$ collisions at a centre-of-mass energy of $8~mathrm{TeV}$, which are the most precise data from Run I of the LHC for this process, where a good description of the data is achieved. To allow this comparison we have performed an unfolding of the data, which overcomes the long-standing issue that the experimental and theoretical definitions of jet flavour are incompatible.
Inclusive Higgs boson production at large transverse momentum is induced by different production channels. We focus on the leading production through gluon fusion, and perform a consistent combination of the state of the art calculations obtained in the infinite-top-mass effective theory at next-to-next-to-leading order (NNLO) and in the full Standard Model (SM) at next-to-leading order (NLO). We thus present approximate QCD predictions for this process at NNLO, and a study of the corresponding perturbative uncertainties. This calculation is then compared with those obtained with commonly used event generators, and we observe that the description of the considered kinematic regime provided by these tools is in good agreement with state of the art calculations. Finally, we present accurate predictions for other production channels such as vector boson fusion, and associated production with a gauge boson, and with a $tbar{t}$ pair. We find that, at large transverse momentum, the contribution of other production modes is substantial, and therefore must be included for a precise theory prediction of this observable.
We present predictions for a variety of single-inclusive observables that stem from the production of charm and bottom quark pairs at the 7 TeV LHC. They are obtained within the FONLL semi-analytical framework, and with two Monte Carlo + NLO approaches, MC@NLO and POWHEG. Results are given for final states and acceptance cuts that are as close as possible to those used by experimental collaborations and, where feasible, are compared to LHC data.
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