Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userCollinear expansion for color singlet cross sections
112
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We demonstrate how to efficiently expand cross sections for color-singlet production at hadron colliders around the kinematic limit of all final state radiation being collinear to one of the incoming hadrons. This expansion is systematically improvable and applicable to a large class of physical observables. We demonstrate the viability of this technique by obtaining the first two terms in the collinear expansion of the rapidity distribution of the gluon fusion Higgs boson production cross section at next-to-next-to leading order (NNLO) in QCD perturbation theory. Furthermore, we illustrate how this technique is used to extract universal building blocks of scattering cross section like the N-jettiness and transverse momentum beam function at NNLO.
rate research
Read More
306 -
Jonathan Estevez
, Felipe J. Llanes-Estrada
, Victor Martinez-Fernandez (Nat. Center for Nuclear Research
2020
We present a new computation in a field-theoretical model of Coulomb gauge QCD of the first radial and angular excitations of a qqq system in a SU(3) flavor singlet state, Lambda_S. The traditional motivation for the study is that the absence of flavor singlets in the lowest-lying spectrum is a direct consequence of the color degree of freedom. (The calculation is tested with decuplet baryons Delta(1232) and Omega(1672).) We also analyze decay branching fractions of the flavor singlet baryon for various masses with the simplest effective Lagrangians.
Pair production of massive coloured particles in hadron collisions is accompanied by potentially large radiative corrections related to the suppression of soft gluon emission and enhanced Coulomb exchange near the production threshold. We recently developed a framework to sum both series of corrections for the partonic cross section using soft-collinear and non-relativistic effective theory. If it can be argued that the resummed cross section approximates the complete result over a significant kinematic range, an improvement of the hadronic cross section results, even when the production is not kinematically constrained to the threshold. This is discussed here for the case of top quark production.
With quark-antiquark annihilation and creation in the first Born approximation, we study the reactions: $K bar {K} to K bar {K}^ast, ~K bar{K} to K^* bar{K}, ~pi K to pi K^ast, ~pi K to rho K, ~pi pi to K bar{K}^ast, ~pi pi to K^ast bar{K}, ~pi pi to K^ast bar{K}^ast, ~pi rho to K bar{K}, ~pi rho to K^ast bar{K}^ast, ~rho rho to K^ast bar{K}^ast, ~K bar{K}^ast to rho rho$, and $K^* bar{K} to rho rho$. Unpolarized cross sections for the reactions are obtained from transition amplitudes that are composed of mesonic quark-antiquark relative-motion wave functions and the transition potential for quark-antiquark annihilation and creation. From a quark-antiquark potential that is equivalent to the transition potential, we prove that the total spin of the two final mesons may not equal the total spin of the two initial mesons. Based on flavor matrix elements, cross sections for some isospin channels of reactions can be obtained from the other isospin channels of reactions. Remarkable temperature dependence of the cross sections is found.
We estimate the theoretical uncertainties of the model developed in Phys. Rev. C70 055503 for inclusive quasielastic charged-current neutrino-nucleus reactions at intermediate energies. Besides we quantify the deviations of the predictions of this many body framework from those obtained within a simple Fermi gas model. An special attention has been paid to the ratio sigma(mu)/sigma(e) of interest for experiments on atmospheric neutrinos. We show that uncertainties affecting this ratio are likely smaller than 5%
The experimental results of the future electron -- ion ($e A$) collider are expected to constrain the dynamics of the strong interactions at small values of the Bjorken -- $x$ variable and large nuclei. Recently it has been suggested that Coulomb corrections can be important in inclusive and diffractive $eA$ interactions. In this paper we present a detailed investigation of the impact of the Coulomb corrections to some of the observables that will be measured in the future $eA$ collider. In particular, we estimate the magnitude of these corrections for the charm and longitudinal cross sections in inclusive and diffractive interactions. Our results demonstrate that the Coulomb corrections for these observables are negligible, which implies that they can be used to probe the QCD dynamics.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
