arXiv subjects

A. Limphirat

Publications and source records attributed to A. Limphirat.

14 recordsLinked to original sources

arXiv2025

Effect of construction steels on PMTs detection efficiency at JUNO

We study the impact of the carbon steel rebars and the steel TT bridge within the JUNO structure on the shielding effect of the coils. Our simulations demonstrate that despite the presence of carbon steel structures of the rebars of the water pool and the TT bridge within the central detector vicinity, the residual magnetic field experienced by the PMTs remains within the acceptable limit established by the JUNO experiment of 10% for CD-PMTs and 20% for Veto-PMTs, compared to the geomagnetic field. The maximum magnetic fields experienced by the CD-PMTs and Veto-PMTs are 9% and 18% of the geomagnetic field strength, respectively. These findings indicate that the residual magnetic field has minimal impacts on the PMTs detection efficiency.

physics.ins-det↗

arXiv2025

Investigation of $\Delta(1232)$ resonance substructure in $p\gamma^*\to \Delta(1232)$ process through helicity amplitudes

This work investigates the substructure of the $\Delta(1232)$ resonance in the $p\gamma^*\to \Delta(1232)$ process through helicity transition amplitudes within the quark model framework. We consider the involved baryons composed of three quarks, and both the quark core and meson cloud contribute to the transition amplitudes. The comparison of theoretical results with experimental data reveals that, rather than the $L=0$ component of the $\Delta(1232)$ resonance, it is the $L=2$ component that significantly affects its $S_{1/2}$ amplitude. These findings indicate that the $\Delta(1232)$ resonance likely contains a substantial $L=2$ component, challenging the conventional view of the $\Delta(1232)$ resonance as an $L=0$ baryon.

hep-ph↗

arXiv2023

Axial transition form factors of octet baryons in the perturbative chiral quark model

We study the axial transition form factors $G_A^{B\to B'}(Q^2)$ as well as the axial charges $g_A^{B\to B'}$ of the octet baryons in the perturbative chiral quark model~(PCQM) with including both the ground and excited states in the intermediate quark propagators. The PCQM results on the $G_A^{B\to B'}(Q^2)$ and the $g_A^{B\to B'}$ are found in good agreement with the existing experimental data and the lattice-QCD values. The study figures out that the $G_A^{B\to B'}(Q^2)$ for all transitions behave in the dipolelike form, which is dominantly caused by the three-quark core. The meson cloud with the ground-state quark propagator also plays an extremely important role but results in a flat contribution. The excited-state quark propagator contributing to the $G_A^{B\to B'}(Q^2)$ could be regarded as the higher order correction and it is very limited.

hep-ph↗

arXiv2022

Study of $N(1520)$ and $N(1535)$ structures via $γ^p\to N^$ transitions

The helicity amplitudes of the $N(1520)$ and $N(1535)$ resonances in the $γ^*p\to N^*$ electromagnetic transition are studied in the constituent quark model using the impulse approximation, with the proton and resonances assumed to be in three-quark configurations. The comparison of theoretical results and experimental data on the helicity amplitudes $A_{1/2}$, $A_{3/2}$, and $S_{1/2}$ indicates that the $N(1520)$ and $N(1535)$ resonances are primarily composed of three-quark $L=1$ states but may contain additional components. However, it is improbable that contributions from meson clouds will be dominant at low $Q^2$.

hep-ph↗

arXiv2021

The study of active geomagnetic shielding coils system for JUNO

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator (LS) detector for neutrino mass ordering and other neutrino physics research. The detector uses large-size $20$ inches photomultiplier tubes to detect photons from a liquid scintillator. The large PMTs are sensitive and easily affected such that the detection efficiency loses about 60$\%$ under the geomagnetic field intensity ($\sim$500 mG). It has a significantly negative effect on the detector performance, and a compensation system is necessary for geomagnetic field shielding. As permalloys are easily rusted in water, a better way for the geomagnetic shielding is to apply an active compensation coils system. The simulations show that a set of 32 circular coils can meet the experiment requirement. The residual magnetic field is less than 0.05 G in the Central Detector Photomultiplier Tube (CD-PMT) region (38.5-39.5 m in diameter). A prototype coil system with a 1.2 m was built to validate the simulation and the design. The measured data of prototype and simulation results are consistent with each other, and geomagnetic field intensity is effectively reduced by coils, verifying the shielding coils system design for JUNO. This study is expected to provide practical guidance for the PMT magnetic field shielding for future large-scale detector designs.

physics.ins-det↗

arXiv2021

Study of $N(1440)$ structure via $γ^*p\to N(1440)$ transition

We study the photoproduction of the $N(1440)$ resonance in $γ^*p\to N^*$ process in quark models, where the $N(1440)$ takes different wave functions: first radial excitation of the nucleon imported from low-lying baryon mass spectrum calculations, a general radial excitation of the nucleon, and a $q^3$ state with positive parity. The comparison between the theoretical results and experimental data on the helicity amplitudes $A_{1/2}$ and $S_{1/2}$ and the analysis of the spatial wave function of the $N(1440)$ resonance reveal that the $N(1440)$ resonance is mainly the $q^3$ first radial excitation.

hep-ph↗

arXiv2019

Analysis of excited quark propagator effects on neutron charge form factor

The charge form factor and charge radius of neutron are investigated in the perturbative chiral quark model (PCQM) with considering both the ground and excited states in the quark propagator. A Cornell-like potential is extracted in accordance with the predetermined ground state quark wavefunction, and the excited quark states are derived by solving the Dirac equation with the extracted PCQM potential numerically. The study reveals that the contributions of the excited quark states are considerably influential in the charge form factor and charge radius of neutron as expected, and the total results are significantly improved and increased by nearly four times by including the excited states in the quark propagator. The theoretical PCQM results are found, including the ground and excited quark propagators, in good agreement with the recent lattice QCD values at pion mass of about 130 MeV.

hep-ph↗

arXiv2017

Higher order net-proton number cumulants dependence on the centrality definition and other spurious effects

We study the dependence of the normalized moments of the net-proton multiplicity distributions on the definition of centrality in relativistic nuclear collisions at a beam energy of $\sqrt{s_{\mathrm{NN}}}= 7.7$ GeV. Using the UrQMD model as event generator we find that the centrality definition has a large effect on the extracted cumulant ratios. Furthermore we find that the finite efficiency for the determination of the centrality introduces an additional systematic uncertainty. Finally, we quantitatively investigate the effects of event-pile up and other possible spurious effects which may change the measured proton number. We find that pile-up alone is not sufficient to describe the data and show that a random double counting of events, adding significantly to the measured proton number, affects mainly the higher order cumulants in most central collisions.

nucl-th↗

arXiv2017

Comparisons of electric charge and axial charge meson cloud distributions in the PCQM

The meson cloud distributions in $r$-space are extracted from the nucleon electromagnetic and axial form factors which are derived in the perturbative chiral quark model. The theoretical results indicate that the electric charge and axial charge distributions of the three-quark core are the same, the magnetic charge distributions of the meson cloud and three-quark core are more or less in the same region and peak at distances of around 2 $\rm GeV^{-1}$, but the axial charge meson cloud distributes mainly inside the three-quark core.

hep-ph↗

arXiv2015

Role of pentaquark components in $ϕ$ meson production proton-antiproton annihilation reactions

The pentaquark component is included in the proton wave functions to study phi meson production proton-antiproton annihilation reactions. With all possible configurations of the uuds subsystem proposed for describing the strangeness spin and magnetic moment of the proton, we estimate the branching ratios of the annihilation reactions at rest proton-antiproton to phi + X (X=pi, eta, rho, omega) from atomic proton-antiproton S- and P-wave states by using effective quark line diagrams incorporating the 3P0 model. The best agreement of theoretical prediction with the experimental data is found when the pentaquark configuration of the proton wave function takes the flavor-spin symmetry, [4]_FS [22]_F [22]_S.

hep-ph↗

arXiv2015

Meson cloud contributions to baryon axial form factors

The axial form factor as well as the axial charge of octet baryons are studied in the perturbative chiral quark model (PCQM) with the quark wave functions predetermined by fitting the theoretical results of the proton charge form factor to experimental data. The theoretical results are found, based on the predetermined quark wave functions, in good agreement with experimental data and lattice values. This may indicate that the electric charge and axial charge distributions of the constituent quarks are the same. The study reveals that the meson cloud plays an important role in the axial charge of octet baryons, contributing 30%-40% to the total values, and strange sea quarks have a considerable contribution to the axial charge of the $Σ$ and $Ξ$.

hep-ph↗

arXiv2014

Study of baryon octet electromagnetic form factors in perturbative chiral quark model

The electromagnetic properties of baryon octet are studied in the perturbative chiral quark model (PCQM). The relativistic quark wave function is extracted by fitting the theoretical results of the proton charge form factor to experimental data and the predetermined quark wave function is applied to study the electromagnetic form factors of other octet baryons as well as magnetic moments, charge and magnetic radii. The PCQM results are found, based on the predetermined quark wave function, in good agreement with experimental data.

hep-ph↗

arXiv2014

Reaction $e^+e^-\to\bar DD$ and $ψ'$ mesons

We study the reaction $e^+e^-\to\bar DD$ near threshold in the $^3P_0$ non-relativistic quark model, including as intermediate states the $J/ψ$, $ψ(2S)$, $ψ(3770)$ and $ψ(4040)$ mesons. The work reveals that experimental data strongly favor one of the two $ψ(2S)-ψ(3770)$ mixing angles derived by fitting to the $e^-e^+$ partial decay widths of the $ψ(2S)$ and $ψ(3770)$ mesons. The meson $X(3940)$ as well as the resonance around 3.9 GeV observed by Belle and BaBar Collaborations in the reaction $e^+e^-\rightarrow \bar DD$ is unlikely to be a $c\bar c$ $I^G(J^{PC})=0^-(1^{--})$ state.

hep-ph↗

arXiv2007

Bottom Baryon Decays in Non-relativistic Quark Model

The reactions $Σ_b^* \to Λ_b π$, $Σ_b \to Λ_b π$, and $Ξ_b^* \to Ξ_b π$ are studied in the $^3P_0$ non-relativistic quark model with all the model parameters fixed in the sector of light quarks. The theoretical predictions for the decay widths $Γ_{Σ_b^* \to Λ_b π}$ and $Γ_{Σ_b \to Λ_b π}$ are consistent with the experimental data of the CDF Collaboration. Using as an input the recent mass of $Ξ_b$ and the theoretical predictions mass of $Ξ_b^{*}$, a narrow decay width about 1 MeV is predicted for the bottom baryon $Ξ_b^*$. The work suggests that the $^3P_0$ quark dynamics is of independence of environments where heavy quarks may or may not be a component of baryons.

hep-ph↗