Exploring SMEFT Couplings Using the Forward-Backward Asymmetry in Neutral Current Drell-Yan Production at the LHC

Neutral current Drell-Yan (DY) lepton-pair production is considered in the framework of the Standard Model Effective Field Theory (SMEFT). Using the open-source fit platform xFitter, we investigate the impact of high-statistics measurements of the neutral current DY (NCDY) forward-backward asymmetry $A_{\rm{FB}}$ near the weak boson mass scale in the present and forthcoming stages of the Large Hadron Collider (LHC). Besides recovering earlier results on the $A_{\rm{FB}}$ sensitivity to parton distribution functions, we analyze the precision determination of $Z$-boson couplings to left-handed and right-handed $u$-quarks and $d$-quarks, and explore Beyond-Standard-Model contributions using the SMEFT framework. We comment on the role of the $A_{\rm{FB}}$ asymmetry for the electroweak SMEFT fit and precision $Z$-boson physics at the LHC and high-luminosity HL-LHC

Comparison of CMS measurements with predictions at NLO applying the Parton Branching Method and PYTHIA

In August 2023, more than 30 students joined the Special Remote DESY summer-school to work on projects of importance for LHC experiments. In a dedicated initiative, analyses that had not been incorporated into the RIVET package were implemented and verified. Here, a brief description of the accomplished work is given, and a comparison of the measurements with predictions obtained from matched standard parton shower Monte Carlo event generators as well as with those obtained from Parton-Branching TMDs with corresponding parton showers are presented

TMD densities at leading and higher order from the noParton Branching method

We present a new determination of Transverse Momentum Dependent (TMD) parton distributions obtained with the Parton Branching (PB) method at LO, NLO and NNLO. The PB TMDs are extracted from fits to precision DIS data using DGLAP splitting functions at leading and higher order. We extract both the collinear part and the transverse momentum dependent part of the parton densities.In addition the fit sensitivity to dynamical resolution scales on TMD evolution in different kinematical region of x and Q2 will be investigated

Effect of low-Q2Q^2 DIS data on fits to TMD parton distributions

A new parton-branching Monte Carlo method has been recently presented to solve the QCDDGLAP evolution equations. It has been used to construct both collinear and transverse momentumdependent (TMD) parton distribution functions. Based on this method, we perform fits to therecently released high-precision deep inelastic scattering (DIS) measurements, and examine theimpact of low-$Q^2$ data on TMD distributions

Determination of collinear and TMD photon densities using the Parton Branching method

We present the first determination of transverse momentum dependent (TMD) photon densities with the Parton Branching method. The photon distribution is generated perturbatively without intrinsic photon component. The input parameters for quarks and gluons are determined from fits to precision measurements of deep inelastic scattering cross sections at HERA. The TMD densities are used to predict the mass and transverse momentum spectra of very high mass lepton pairs from both Drell-Yan production and Photon-Initiated lepton processes at the LHC

Determination of collinear and TMD photon densities using the Parton Branching method

We present the first determination of transverse momentum dependent (TMD) photon densities with the Parton Branching method. The photon distribution is generated perturbatively without intrinsic photon component. The input parameters for quarks and gluons are determined from fits to precision measurements of deep inelastic scattering cross sections at HERA. The TMD densities are used to predict the mass and transverse momentum spectra of very high mass lepton pairs from both Drell-Yan production and Photon-Initiated lepton processes at the LHC

High-pTp_T Azimuthal Correlations of Z jet and Multi-jet Production

In this study, we present our latest findings regarding azimuthal distributions in vector boson + jets and multi-jet production at the Large Hadron Collider (LHC). These findings result from matching next-to-leading order (NLO) perturbative matrix elements with transverse momentum dependent (TMD) parton branching. We conduct a comprehensive comparative analysis of azimuthal correlations between Z boson-jet and jet-jet systems in the back-to-back region. These distinct azimuthal correlation patterns can help identify potential factorization-breaking effects in this region. Such effects depend on the different color and spin structures of the final states and their interactions with the initial states