Azimuthal correlations of high transverse momentum jets at next-to-leading order in the parton branching method

The azimuthal correlation, $$\Delta \phi _{12}$$ Δ ϕ 12 , of high transverse momentum jets in pp collisions at $$\sqrt{s}=13$$ s = 13 TeV is studied by applying PB-TMD distributions to NLO calculations via MCatNLO together with the PB-TMD parton shower. A very good description of the cross section as a function of $$\Delta \phi _{12}$$ Δ ϕ 12 is observed. In the back-to-back region of $${\Delta \phi _{12}}\rightarrow \pi $$ Δ ϕ 12 → π , a very good agreement is observed with the PB-TMD Set 2 distributions while significant deviations are obtained with the PB-TMD Set 1 distributions. Set 1 uses the evolution scale while Set 2 uses transverse momentum as an argument in $$\alpha _\mathrm {s}$$ α s , and the above observation therefore confirms the importance of an appropriate soft-gluon coupling in angular ordered parton evolution. The total uncertainties of the predictions are dominated by the scale uncertainties of the matrix element, while the uncertainties coming from the PB-TMDs and the corresponding PB-TMD shower are very small. The $$\Delta \phi _{12}$$ Δ ϕ 12 measurements are also compared with predictions using MCatNLO together Pythia8, illustrating the importance of details of the parton shower evolution.

Study of transverse momentum and nuclear modification factors distribution of charged particles produced in pp and Pb–Pb collisions at s NN = 2.76TeV and 5.02TeV

We have studied transverse momentum distributions of charged particles produced in pp and Pb–Pb collisions at [Formula: see text] TeV and 5.02 TeV in the pseudorapidity interval [Formula: see text] and transverse momentum range [Formula: see text][Formula: see text]GeV/[Formula: see text]. We simulated data using EPOS-LHC, EPOS-1.99 and QGSJETII-04 models. The simulation data is compared with the ALICE experimental data values at [Formula: see text] TeV and 5.02 TeV for pp and most central Pb–Pb collisions. It has been observed that, EPOS-LHC and QGSJETII-04 models explain the experimental results for pp collision at [Formula: see text] TeV and 5.02 TeV. The behavior of nuclear modification factors has been studied. The simulation codes of all three models EPOS-LHC, EPOS-1.99 and QGSJETII-04 overestimate the experimental results at low transverse momentum interval: [Formula: see text] GeV/[Formula: see text], for Pb–Pb collisions at [Formula: see text] TeV and 5.02 TeV. However, only EPOS-LHC model can explain the experimental data at high transverse momentum in the range: [Formula: see text] GeV/[Formula: see text]. EPOS-1.99 and QGSJETII-04 underestimate in the region of Cronin effect and cannot give satisfactory estimates for the [Formula: see text] values for which [Formula: see text] demonstrates stronger suppression because of the collective parton effect. It can be inferred that these effects are not taken into account in EPOS-1.99 and QGSJETII-04 models. These models, however, satisfactorily explain the ALICE experimental data in the ranges of [Formula: see text] for which nuclear modification factor [Formula: see text] shows rising trend.

In-medium modification of dijets in PbPb collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ = 5.02 TeV

Modifications to the distribution of charged particles with respect to high transverse momentum (pT) jets passing through a quark-gluon plasma are explored using the CMS detector. Back-to-back dijets are analyzed in lead-lead and proton-proton collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ s NN = 5.02 TeV via correlations of charged particles in bins of relative pseudorapidity and angular distance from the leading and subleading jet axes. In comparing the lead-lead and proton-proton collision results, modifications to the charged-particle relative distance distribution and to the momentum distributions around the jet axis are found to depend on the dijet momentum balance xj , which is the ratio between the subleading and leading jet pT. For events with xj ≈ 1, these modifications are observed for both the leading and subleading jets. However, while subleading jets show significant modifications for events with a larger dijet momentum imbalance, much smaller modifications are found for the leading jets in these events.

Precision SMEFT bounds from the VBF Higgs at high transverse momentum

We study the production of Higgs bosons at high transverse momenta via vector-boson fusion (VBF) in the Standard Model Effective Field Theory (SMEFT). We find that contributions from four independent operator combinations dominate in this limit. These are the same ‘high energy primaries’ that control high energy diboson processes, including Higgs-strahlung. We perform detailed collider simulations for the diphoton decay mode of the Higgs boson as well as the three final states arising from the ditau channel. Using the quadratic growth of the SMEFT contributions relative to the Standard Model (SM) contribution, we project very stringent bounds on these operators that far surpass the corresponding bounds from the LEP experiment.