Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userSearching for the rules that govern hadron construction
52
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Just as Quantum Electrodynamics describes how electrons are bound in atoms by the electromagnetic force, mediated by exchange of photons, Quantum Chromodynamics (QCD) describes how quarks are bound inside hadrons by the strong force, mediated by exchange of gluons. At face value, QCD allows hadrons constructed from increasingly many quarks to exist, just as atoms with increasing numbers of electrons exist, yet such complex constructions seemed, until recently, to not be present in nature. In what follows we describe advances in the spectroscopy of mesons that are refining our understanding of the rules for building hadrons from QCD.
rate research
Read More
QCD instantons are arguably the best motivated yet unobserved nonperturbative effects predicted by the Standard Model. A discovery and detailed study of instanton-generated processes at colliders would provide a new window into the phenomenological exploration of QCD and a vastly improved fundamental understanding of its non-perturbative dynamics. Building on the optical theorem, we numerically calculate the total instanton cross-section from the elastic scattering amplitude, also including quantum effects arising from resummed perturbative exchanges between hard gluons in the initial state, thereby improving in accuracy on previous results. Although QCD instanton processes are predicted to be produced with a large scattering cross-section at small centre-of-mass partonic energies, discovering them at hadron colliders is a challenging task that requires dedicated search strategies. We evaluate the sensitivity of high-luminosity LHC runs, as well as low-luminosity LHC and Tevatron runs. We find that LHC low-luminosity runs in particular, which do not suffer from large pileup and trigger thresholds, show a very good sensitivity for discovering QCD instanton-generated processes.
A Hadron Blind Detector (HBD) has been developed, constructed and successfully operated within the PHENIX detector at RHIC. The HBD is a Cherenkov detector operated with pure CF4. It has a 50 cm long radiator directly coupled in a window- less configuration to a readout element consisting of a triple GEM stack, with a CsI photocathode evaporated on the top surface of the top GEM and pad readout at the bottom of the stack. This paper gives a comprehensive account of the construction, operation and in-beam performance of the detector.
We investigate the processes $e^+e^-$$to$$gamma J/psiphi$, $gamma J/psiomega$ and $pi^0 J/psieta$ to search for the charmnium-like states with hidden $sbar{s}$, such as $Y(4140)$, $Y(4274)$, $X(4350)$ and $X(3915)$. These processes will receive contributions from the charmed-strange meson rescatterings. When the center-of-mass energies of the $e^+e^-$ scatterings are taken around the $D_{s0}(2317)D_s^{*}$, $D_{s1}(2460)D_s$ or $D_{s1}(2460)D_s^{*}$ threshold, the anomalous triangle singularities can be present in the rescattering amplitudes, which implies a non-resonance explanation about the resonance-like structures. The positions of the anomalous triangle singularities are sensitive to the kinematics, which offers us a criterion to distinguish the kinematic singularities from genuine particles.
We investigate the anomalous triangle singularity (ATS) and its possible manifestations in various processes. We show that the ATS should have important impact on our understanding of the nature of some newly observed threshold states. Discussions on how to distinguish the ATS phenomena from genuine dynamic pole structures are presented.
A spectrum of massive graviton states is present in several recent theoretical models that include extra space dimensions. In some such models the graviton states are well separated in mass, and can be detected as resonances in collider experiments. The ability of the ATLAS detector at the Large Hadron Collider to identify such states and measure their properties is considered, in the case that the resonances are narrow compared to the experimental resolution. The discovery limits for the detection of the decay mode G->e+e- are derived. The angular distribution of the lepton pair is used to determine the spin of the intermediate state. In one specific model, the resonance can be detected up to a graviton resonance mass of 2080 GeV, while the angular distribution favours a spin-2 hypothesis over a spin-1 hypothesis at 90% confidence for resonance masses up to 1720 GeV.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
