Theory Of Quantum Chromodynamics Research Articles

On Theoretical Aspect of Photons Emission From Quark-Gluon Interaction Upon Hard Collision

Abstract This work applies a quantum chromodynamics theory QCD to photon emission from heavy quark-gluon scattering in the strong interaction quark-gluon to study and calculate photon flow in hard interaction processes. The photon flow from the dense quark-gluon interaction was calculated using critical temperature, quantum chromodynamic coupling and fugacity at chemical potential μq (500 MeV) for the anti-top with gluon interaction in t ¯ g → s ¯ γ system. The photon flow spectrum in hard collisions is described under the first leading order approximation for QCD theory at finite chemical potential and critical temperature using various photon energy values dependent on the fugacity of quark and gluon. Photon flux calculation provided valuable insights into QGP conditions. The coupling strength αc (T) calculation is a strongly decreasing function of critical temperature ranging 107MeV ≤ Tc ≤ 145MeV and also find appreciable increasing as a result of increasing temperature of system ranging 180MeV ≤ T ≤ 360MeV. The photon flow produced in the t ¯ g → s ¯ γ system was observed in the low range of photon energy with two critical temperatures. The total photon emission strongly decreases marginally as a function of the increase in photon energy. The photon flow emission was found to have appreciable enhancement at the anti-top quark interaction with gluon and it increases highly as a result of the increased temperature of the system and reaches to maximum near 360 MeV at minimum strength coupling in the energy of the photon 1GeV≤E≤2 GeV.

Study of Photon Emission at High Temperature of Quark Gluon Interaction

In this paper, the photons emission rate from the interaction of quark with gluon is calculated and studied based on quantum chromodynamics theory. The photonic rate is calculated for u g→d g γ system at bremsstrahlung processes with Bag constant B1/4=0.235GeV and B1/4=0.275GeV, system temperature (325-625) MeV and the value of fugacity of quark λQ=0.9 and gluon λG=0.02 to emit photons with energy 0.5 ≤ Eγ ≤ 5GeV in hadronic phase. The effect of system temperature on the photons emission rate was studied and discussed, it was found that it increases with increases of system temperature and decreases of coupling strength due to the deconfinement phenomena furthermore the photonic yield at B1/4=0.235GeV is less than the photonic yield at B1/4=0.275GeV.

Phase diagram determination at fivefold nuclear compression

In the standard model of particle physics, the strong force is characterized by the theory of quantum chromodynamics (QCD). It is commonly understood from QCD properties that hadrons, at sufficiently high temperatures or densities, melt into their constituent quarks, thereby undergoing a deconfinement transition to a new phase of quarks and gluons, often referred to as quark matter or quark-gluon plasma (QGP) [1,2]. Although QGP has been observed in relativistic heavy-ion collisions [3,4], uncertainties remain about when the onset of deconfinement occurs. After comparing simulations from a reliable hadron and quark relativistic transport model with recent data from the STAR experiment, we determined that the onset of the hadron-quark phase transition occurs at about five times nuclear compression, corresponding to temperature T∼ 112 MeV and baryon chemical potential μB∼ 586 MeV, in the nuclear matter phase diagram. This discovery has significant implications for the studies of both the early and present universe [5], including the fraction of dark matter formed in the early universe [6–8] and the structure and dynamics of neutron stars and their mergers [9].

Realization of Wilson fermions in topolectrical circuits

The Wilson fermion (WF) is a fundamental particle in the theory of quantum chromodynamics. Theoretical calculations have shown that the WF with a half skyrmion profile represents a quantum anomalous semimetal phase supporting a chiral edge current, but the experimental evidence is still lacking. In this work, we report a direct observation of the WF in circuit systems. We find that WFs manifest as topological spin textures analogous to the half skyrmion, half-skyrmion pair, and Néel skyrmion structures, depending on their mass. Transformations of different WF states are realized by tuning the electric elements. We further experimentally observe the propagation of chiral edge current along the domain-wall separating two circuits with contrast fractional Chern numbers. Our work provides experimental evidence for WFs in topolectrical circuits. The nontrivial analogy between the WF state and the skyrmionic structure builds an intimate connection between the two burgeoning fields.

Theoretical evaluation of solar proton-proton fusion reaction rate and its uncertainties

The weak proton-proton fusion into a deuteron (2H) is the driving reaction in the energy production in the Sun, as well as similar main sequence stars. Its reaction rate in the solar interior is determined only theoretically. Here, we provide a new determination of the rate of this reaction in solar conditions S11(0), and analyze theoretical and experimental sources for uncertainties, using effective field theory of Quantum Chromodynamics without explicit pions at next-to-leading order. This prediction procedure is verified and validated using experimentally measured set of electromagnetic reactions, which we show to be analogous in their operator structure and properties to the weak sector, and are reproduced within the assessed theoretical uncertainty, using the same approach. We find an enhancement of S11 by 1−4% over the previously recommended value. This change reduces the calculated fluxes of neutrinos originating in 8B and 7Be nuclear reactions in the Sun, thus favoring higher abundances for metallic photospheric elements, in the tension between different composition determination, known as the “Solar Composition Problem”.

Calculation of the Rate of Photons Emission from Charm-Gluon Interaction

In this research, the rate of photons emission from quark-gluon interaction based on the quantum chromodynamics theory was calculated. The rate of photons emission was evaluated for

QCD at the amplitude level: Fock state interference in heavy quark electroproduction

Quantum chromodynamics (QCD) rigorously predicts the existence of both nonperturbative intrinsic and perturbative extrinsic heavy quark contents of nucleons. In this article we discuss the heavy quark electroproduction on protons induced by the Fock states ∣uud + g〉 of three valence quarks in the proton and a nonperturbative gluon, and the mid uud+Qoverline{Q}Bigrangle non-perturbative state of three valence quarks and a heavy quark-antiquark pair. The first one gives the perturbative contribution when the gluon produces a heavy quark pair, while the second is the intrinsic part, and they produce amplitude interference. We use nonperturbative light-front wavefunctions for these Fock states, which are computed using the color-confining light-front holographic QCD theory. Due to interference of the amplitudes corresponding to the intrinsic and extrinsic heavy quark contribution to the proton a novel Q vs. overline{Q} asymmetry emerges in the differential cross section of the electroproduction off a proton {d}^2{sigma}_{e^{-}p}/left( dxd{Q}^2right) . Our analysis proposed a novel asymmetry in QCD between intrinsic and extrinsic heavy quark content in nucleon and provides new insights into the physics of heavy quark phenomena in QCD at the amplitude level. This asymmetry is similar to the Brodsky-Gillespie asymmetry discovered before in QED case and confirmed at DESY.

Kaonic atoms measurements with SIDDHARTA-2

The SIDDHARTA-2 collaboration is aiming to perform the challenging measurement of kaonic deuterium X-ray transitions to the ground state. This will allow to extract the isospin-dependent antikaon-nucleon scattering lengths, providing input to the theory of Quantum Chromodynamics (QCD) in the non-perturbative regime with strangeness. This work describes the SIDDHARTA-2 experimental apparatus and presents the results obtained during the commissioning phase realized with kaonic helium measurements. In particular, the first observation of the kaonic helium transitions to the 3s level (M-lines), reported in this work, represents a new source of information to study the kaonic helium cascade process and demonstrates the potential of the SIDDHARTA-2 apparatus, in the view of the ambitious kaonic deuterium measurement.

Estimates for rare three-body decays of the Ω baryon using chiral symmetry and the ΔI=1/2 rule

We study rare three-body decays of the $\mathrm{\ensuremath{\Omega}}$ baryon using SU(3) chiral perturbation theory, the successful effective field theory of quantum chromodynamics at low energies. At leading order, we calculate the branching fractions of the decay ${\mathrm{\ensuremath{\Omega}}}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Xi}}\ensuremath{\pi}\ensuremath{\pi}$ for all possible combinations of pions. For one channel, we find an order-of-magnitude discrepancy between theory and experiment. This tension is known to exist in the nonrelativistic limit, and we confirm that it remains in the relativistic calculation. Fairly independent of the values of the low-energy constants, we establish lower limits for the branching fractions of these three-body $\mathrm{\ensuremath{\Omega}}$ decays, which reaffirm the gap between theory and experiment. We point out that this discrepancy is closely tied to the $\mathrm{\ensuremath{\Delta}}I=1/2$ selection rule. In turn, this means that the three-body decays constitute an interesting tool to scrutinize the selection rule. Using next-to-leading-order calculations, we also provide predictions for the decay ${\mathrm{\ensuremath{\Omega}}}^{\ensuremath{-}}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Xi}}}^{0}{\ensuremath{\mu}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$. We show that fully differential distributions will provide access to low-energy constants needed in the axial-vector transitions from a decuplet to octet baryon. Since data for all of these rare three-body $\mathrm{\ensuremath{\Omega}}$ decays are scarce (fully differential data are nonexistent), we recommend that they be remeasured at running and upcoming experiments, such as BESIII, LHCb, Belle-II, and PANDA.

Theoretical Calculation of Photon Emission from Quark-Antiquark Annihilation Using QCD Theory

In this work, we calculate and analyze the photon emission from quark and anti-quark interaction during annihilation process using simple model depending on phenomenology of quantum chromodynamic theory (QCD). The parameters, which include the running strength coupling, temperature of the system and the critical temperature, carry information regarding photon emission and have a significant impact on the photons yield. The emission of photon from strange interaction with anti-strange is large sensitive to decreases or increases there running strength coupling. The photons emission increases with decreases running strength coupling and vice versa. We introduce the influence of critical temperature on the photon emission rate in order to facilitate its further applied in photon emission spectrum. Photon emission was increased with large critical temperature MeV comparing with photons emission at critical temperature MeV. We analyze and discuss the sensitive of the emission of photon to photons energy . It increases with decreased photons energy and vice versa. However, the photons emission increases with increases thermal energy of system T = 170 MeV to 270 Mev. It is implied that strength coupling, critical temperature and photons energy can be as important as thermal energy of system for emission of photon.

Axions as a model of Dark Matter

The true nature of dark matter is an extremely important and fundamental problem in the study of astrophysics, particle physics, cosmology and many other areas within the study of physics. This paper presents experimental evidence for the existence of dark matter through discussing the experimental results of mass profiling a galaxy and gravitational lensing. The fundamental properties of dark matter are then discussed, and evidence for these properties is presented. This allows further discussion of one of the most promising models of dark matter - the axion. The purpose of this paper is to present the evidence for the axion model, describe the nature of the theoretical axion particle, and to highlight the effects this model would have on other theories in physics such as solving the Strong CP Problem in the theory of quantum chromodynamics.

Direct observation of the dead-cone effect in quantum chromodynamics

In particle collider experiments, elementary particle interactions with large momentum transfer produce quarks and gluons (known as partons) whose evolution is governed by the strong force, as described by the theory of quantum chromodynamics (QCD)1. These partons subsequently emit further partons in a process that can be described as a parton shower2, which culminates in the formation of detectable hadrons. Studying the pattern of the parton shower is one of the key experimental tools for testing QCD. This pattern is expected to depend on the mass of the initiating parton, through a phenomenon known as the dead-cone effect, which predicts a suppression of the gluon spectrum emitted by a heavy quark of mass mQ and energy E, within a cone of angular size mQ/E around the emitter3. Previously, a direct observation of the dead-cone effect in QCD had not been possible, owing to the challenge of reconstructing the cascading quarks and gluons from the experimentally accessible hadrons. We report the direct observation of the QCD dead cone by using new iterative declustering techniques4,5 to reconstruct the parton shower of charm quarks. This result confirms a fundamental feature of QCD. Furthermore, the measurement of a dead-cone angle constitutes a direct experimental observation of the non-zero mass of the charm quark, which is a fundamental constant in the standard model of particle physics.

Determination of the parton distribution functions of the proton using diverse ATLAS data from pp collisions at sqrt{s} = 7, 8 and 13 TeV

This paper presents an analysis at next-to-next-to-leading order in the theory of quantum chromodynamics for the determination of a new set of proton parton distribution functions using diverse measurements in pp collisions at sqrt{s} = 7, 8 and 13 TeV, performed by the ATLAS experiment at the Large Hadron Collider, together with deep inelastic scattering data from ep collisions at the HERA collider. The ATLAS data sets considered are differential cross-section measurements of inclusive W^{pm } and Z/gamma ^* boson production, W^{pm } and Z boson production in association with jets, tbar{t} production, inclusive jet production and direct photon production. In the analysis, particular attention is paid to the correlation of systematic uncertainties within and between the various ATLAS data sets and to the impact of model, theoretical and parameterisation uncertainties. The resulting set of parton distribution functions is called ATLASpdf21.

Theoretical Study of Hard Photonic Produce from Interaction of Quark-Gluon at Critical Temperature 190 MeV and 196 MeV

The quantum chromodynamics theory approach was taken to study the photonic emission from interaction of quark gluon at high at Bremsstrahlung processes. Strength coupling, quark charge 𝑒𝑞 , flavor number 𝑛𝐹 , thermal energy T of system, fugacity of gluon ƛ𝑔, fugacity of quark ƛ𝑞 , critical temperature 𝑇𝐶 and photons energy 𝐸 are taken to calculate photons rate via the quantum system. Photons emission rate studies and calculates via high energy 400MeV to 650 MeV using flavor number 3 and 7 for 𝑢̅𝑔 → 𝑑̅𝑔𝛾 and 𝑐𝑔 → 𝑠𝑔𝛾 systems at bremsstrahlung processes with critical temperature (𝑇𝑐 = 190 and 196) MeV with photons energy (1-10) GeV. The confinement and de-confinement of quarks behavior at strong force with distances limits investigate theoretically using the strength coupling. The strength coupling increases with increases 𝑛𝐹 and decreases temperature of systems and decrease critical temperature. Photons rate relative to strength coupling, its increases with decreases strength coupling due to increase the temperature. However, the photons produce is high affected with the temperature and critical temperature it decreases with increases the temperature of system and critical temperature and large near created quarks matter and the photons produce increases with decrease the photons energy.

Equilibration of the Quark-Gluon Plasma at Finite Net-Baryon Density in QCD Kinetic Theory

We explore the out-of-equilibrium dynamics of the quark-gluon plasma at zero and finite net-baryon density based on an effective kinetic theory of quantum chromodynamics (QCD). By investigating the isotropization of the longitudinal pressure, we determine the relevant time and temperature scales for the onset of viscous hydrodynamics and quantify the dependence on the chemical composition of the quark-gluon plasma. By extrapolating our results to realistic coupling strength, we discuss phenomenological consequences regarding the role of the preequilibrium phase at different collision energies.

From cosmic matter to the laboratory

AbstractThe recent discovery of binary neutron star mergers has opened a new and exciting venue of research into hot and dense strongly interacting matter. For the first time, this elusive state of matter, described by the theory of quantum chromo dynamics, can be studied in two very different environments. On the macroscopic scale, in the collisions of neutron stars; and on the microscopic scale, in collisions of heavy ions at particle collider facilities. We will discuss the conditions that are created in these mergers and the corresponding high energy nuclear collisions. This includes the properties of quantum chromo dynamics matter, that is, the expected equation of state as well as expected chemical and thermodynamic properties of this exotic matter. To explore this matter in the laboratory, a new research prospect is available at the Facility for Antiproton and Ion Research, FAIR. The new facility is being constructed adjacent to the existing accelerator complex of the GSI Helmholtz Centre for Heavy Ion Research at Darmstadt/Germany, expanding the research goals and technical possibilities substantially. The worldwide unique accelerator and experimental facilities of FAIR will open the way for a broad spectrum of unprecedented research supplying a variety of experiments in hadron, nuclear, atomic, and plasma physics as well as biomedical and material science, which will be briefly described.

Insights into the Origin of Mass

Atomic nuclei are the core of everything we can see. At the first level of approximation, their atomic weights are simply the sum of the masses of all the nucleons they contain. Each nucleon has a mass mN ≈ 1 GeV, i.e. approximately 2000-times the electron mass. The Higgs boson produces the latter, but what produces the nucleon mass? This is the crux: the vast bulk of the mass of a nucleon is lodged with the energy needed to hold quarks together inside it; and that is supposed to be explained by quantum chromodynamics (QCD), the strong-interaction piece within the Standard Model. This contribution canvasses the potential for a coherent effort in QCD phenomenology and theory, coupled with experiments at existing and planned facilities, to reveal the origin and distribution of mass by focusing on the properties of the strong-interaction Nambu-Goldstone modes. Key experiments are approved at JLab 12; planned with COMPASS++/AMBER at CERN; and could deliver far-reaching insights by exploiting the unique capabilities foreseen at an electron ion collider.

Theoretical Study of the Photons Production Kinetic In Hot Quark-Gluon Plasma Matter

In this paper, we study flow of photons rate production in a quark-gluon QG plasma. General theory of this study is based on the field theory for hard interaction. The kinetic of photons production from hard interaction in charm with anti-top to production photons with gluon due to plasma phase at high temperatures (150, 200,250,300 and 350 MeV) .It has been investigated and studied using the postulate of quantum chromodynamic theory QCD .The photons production rate of hard photons with( GeV) are insensitive to strength coupling and depend mainly on the temperature of system T . Despite the different critical temperature (150 and 190MeV) comes, we find that same order of flow rate photons magnitude in both cases. In both cases, the flow rate of photons production in the QG plasmais increased with increased temperature of system and photons energy and decreases with increases the strength coupling strength.

Chiral Perturbation Theory at NNNLO

Chiral perturbation theory is a much successful effective field theory of quantum chromodynamics at low energies. The effective Lagrangian is constructed systematically order by order in powers of the momentum p2, and until now the leading order (LO), next-to leading order (NLO), next-to-next-to leading order (NNLO) and next-to-next-to-next-to leading order (NNNLO) have been studied. In the following review we consider the construction of the Lagrangian and in particular focus on the NNNLO case. We in addition review and discuss the pion mass and decay constant at the same order, which are fundamental quantities to study for chiral perturbation theory. Due to the large number of terms in the Lagrangian and hence low energy constants arising at NNNLO, some remarks are made about the predictivity of this effective field theory.

Flow Production Rate of Hard Photons Probes of Quark–Anti Quark Annihilation Processes at Plasma Phase

The flow emission rate of hard photons from lowest order the QCD processes for quark-anti quark annihilation processes in plasma media at high temperatures (175, 200, 225, 250 and 275 MeV) have been study. In these framework photons, the flow photons emission is calculate according to quark-antiquark annihilation using the quantum chromodynamic theory and solves the ultrarelativistic equation with MATLAP program. Due to the results, we show increases flow photons rate with increases strength coupling and increases with increases temperature of media, it indicate that logarithmically divergent thermal effect on photons product. The critical temperature (Tc=155 to 195 MeV) effect on the quarks confined in hadronic matter phase, it is important parameter effect on strength coupling with flavour number. The flow photons rate spectra show decreasing with increasing th photons energy, it indicate the processes at hadronic phase.