Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userGluon emission at small longitudinal momenta in the QCD effective action approach
44
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
In the framework of the QCD effective action the vertices of gluon emission in interaction of reggeons are studied in the limit of small longitudinal momenta of the emitted gluon. It is found that the vertices drastically simplify in this limit so that the gluon becomes emitted from a single reggeon coupled to the projectile and target via multireggeon vertices. Contribution from this kinematical region is studied for double and 2x2 elementary collisions inside the composite projectile and target.
rate research
Read More
Gluon production on two scattering centers is studied in the formalism of reggeized gluons. Different contributions to the inclusive cross-section are derived with the help of the Lipatov effective action. The AGK relations between these contributions are established. The found inclusive cross-section is compared to the one in the dipole picture and demonstrated to be the same.
We discuss application of formalism of small-$x$ effective action for reggeized gluons, cite{Gribov,LipatovEff,BFKL}, for the calculation of classical gluon field of relativistic color charge, similarly to that done in CGC approach of cite{Venug,Kovner}. The equations of motion with the reggeon fields are solved in LO and NLO approximations and new solutions are found. The results are compared to the calculations performed in the CGC framework and it is demonstrated that the LO CGC results for the classical field are reproduced in our calculations. Possible applications of the NLO solution in the effective action and CGC frameworks are discussed as well.
In this work we apply effective field theory (EFT) to observables in quarkonium production and decay that are sensitive to soft gluon radiation, in particular measurements that are sensitive to small transverse momentum. Within the EFT framework we study $chi_Q$ decay to light quarks followed by the fragmentation of those quarks to light hadrons. We derive a factorization theorem that involves transverse momentum distribution (TMD) fragmentation functions and new quarkonium TMD shape functions. We derive renormalization group equations, both in rapidity and virtuality, which are used to evolve the different terms in the factorization theorem to resum large logarithms. This theoretical framework will provide a systematic treatment of quarkonium production and decay processes in TMD sensitive measurements.
We study the production of the four-lepton final state $l^+ l^- l^+ l^-$, predominantly produced by a pair of electroweak Z bosons, ZZ. Using the LoopSim method, we merge NLO QCD results for ZZ and ZZ+jet and obtain approximate NNLO predictions for ZZ production. The exact gluon-fusion loop-squared contribution to the ZZ process is also included. On top of that, we add to our merged sample the gluon-fusion ZZ+jet contributions from the gluon-gluon channel, which is formally of N^3LO and provides approximate results at NLO for the gluon-fusion mechanism. The predictions are obtained with the VBFNLO package and include the leptonic decays of the Z bosons with all off-shell and spin-correlation effects, as well as virtual photon contributions. We compare our predictions with existing results for the total inclusive cross section at NNLO and find a very good agreement. Then, we present results for differential distributions for two experimental setups, one used in searches for anomalous triple gauge boson couplings, the other in Higgs analyses in the four charged-lepton final state channel. We find that the approximate NNLO corrections are large, reaching up to 20% at high transverse momentum of the Z boson or the leading lepton, and are not covered by the NLO scale uncertainties. Distributions of the four-lepton invariant mass are, however, stable with respect to QCD corrections at this order.
The quark-gluon plasma in stellar structure is investigated using the fluid-like QCD approach. The classical energy momentum tensor relevant for high energy and hot plasma having the nature of fluid bulk of gluon sea is calculated within the model. The transition of gluon field from point particle field inside stable hadrons to relativistic fluid field in hot plasma and vice versa is briefly discussed. The results are applied to construct the equation of state using the Tolman--Oppenheimer--Volkoff equation to describe the hot plasma dominated stellar structure.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
