Conveners
QCD & Heavy Ion Physics: PDFs and Hadrons
- Joey Huston (Michigan State University (US))
QCD & Heavy Ion Physics: Jets and Energy Correlators
- Keping Xie (Michigan State University)
As we push to high precision measurements, the PDF uncertainty is often a limiting factor. To achieve improved precision, our goal is to not only ‘fit’ the PDFs, but to better understand the underlying process at the precision level. Toward this goal, we extend the QCD Parton Model analysis using a factorized nuclear structure model incorporating individual nucleons, and pairs of correlated...
We present a very simple method for calculating the mixed Coulomb-nuclear effects in the $pp$ and $\bar{p}p$ scattering amplitudes, and illustrate the method using simple models frequently used to describe their differential cross sections at small momentum transfers. Combined with the pure Coulomb and form-factor contributions to the scattering amplitude which are known analytically from...
In this work, we complete our CT18qed study with the neutron’s photon parton distribution function (PDF), which is essential for the nucleus scattering phenomenology. Two methods, CT18lux and CT18qed, based on the LUXqed formalism and the DGLAP evolution, respectively, to determine the neutron’s photon PDF have been presented. Various low-Q2 non-perturbative variations have been carefully...
The X(6900) resonance, originally discovered by the LHCb collaboration and later confirmed by both ATLAS and CMS experiments, has sparked broad interests in the fully-charmed tetraquark states. Relative to the mass spectra and decay properties of fully-heavy tetraquarks, our knowledge
on their production mechanism is still rather limited. In this talk, I will discuss the production of S-wave...
Until recently, it was widely believed that every hadron is a composite state of either three quarks or one quark and one antiquark. In the last 20 years, dozens of exotic heavy hadrons have been discovered, and yet no theoretical scheme has unveiled the general pattern. For hadrons that contain more than one heavy quark or antiquark, the Born-Oppenheimer approximation for QCD provides a...
Double-heavy hadrons can be identified as bound states in the Born-Oppenheimer potentials for QCD. We present parameterizations of the 5 lowest Born-Oppenheimer potentials from pure $SU(3)$ lattice gauge theory as functions of the separation $r$ of the static quark and antiquark sources. The parametrizations have the correct limiting behavior at small $r$, where the potentials form...
Energy correlators, which as a jet-substructure observable measure correlations between energy detectors (calorimeters) in a collider experiment, have received significant attention over the last few years in both the theory/phenomenology and experimental communities. This success has prompted investigations into how energy correlators can be further used, such as in the study of both hot and...
Understanding the behaviour of heavy quarks is important for painting a coherent picture of QCD, both formally and phenomenologically, and the upcoming runs at the LHC will provide unprecedented statistics for precision measurements related to heavy flavor. A natural object for initiating these studies are Energy and Charge Correlators, which measure correlations of energy flow, along with the...
We introduce “power jets,” a scheme that uses the fully correlated information of the QCD power spectrum to go beyond conventional, sequential jet clustering algorithms. This affords us a kinematic reconstruction that can accurately probe the underlying hard physics of an event, even in the presence of high pile up, and subject to finite sampling.
In collider physics, the properties of hadronic jets are often measured as a function of their lab-frame momenta. However, jet fragmentation must occur in the particular rest frame of all color-connected particles. Since this frame need not be the lab frame, the fragmentation of a jet depends on the properties of its sibling objects. This non-factorizability of jets has consequences for jet...
The calibration of the energy scale and resolution of jets, the collimated sprays of particles initiated by quarks and gluons, is important for many precision measurements and searches for physics beyond the standard model at the Large Hadron Collider (LHC). Currently within ATLAS, a series of calibrations is required to correct jets for effects of pileup and detector response. This results in...
