The University of Osaka · Physics and Astronomy
Professor Ahmad Jafar Arifi's research lab specializes in theoretical particle physics, focusing on the spectroscopy and decay dynamics of heavy and light baryons, mesons, and their excited resonances within the framework of constituent quark models and light-front quark models. The lab investigates relativistic corrections, spin-parity quantum numbers, and internal quark structures to explain experimental decay widths and mass spectra, particularly for Roper-like resonances in the charmed, bottom, and multistrange baryon sectors. A key emphasis is placed on resolving theoretical ambiguities in current matrix elements and ensuring consistency in light-front formulations through the Bakamjian-Thomas construction.
Figures are computed from collected data and may differ slightly.
We investigate relativistic corrections of an order $1/{m}^{2}$, where $m$ is the constituent quark mass, to heavy baryon decays by emitting one pseudoscalar meson in the quark model. This work is motivated by shortcomings in the previous studies in the nonrelativistic quark model for decays of the Roper-like states, such as ${\mathrm{\ensuremath{\Lambda}}}_{c}(2765)$. We find that the relativistic corrections due to the internal motion of quarks are essential ingredients in improving their deca
Decay properties of multistrangeness $\mathrm{\ensuremath{\Xi}}$ and $\mathrm{\ensuremath{\Omega}}$ baryon resonances are investigated within the constituent quark model by including relativistic corrections. The strong decay widths of various $\mathrm{\ensuremath{\Xi}}$ and $\mathrm{\ensuremath{\Omega}}$ resonances are computed and tested for internal quark configurations to pin down their spin-parity (${J}^{P}$) quantum numbers and internal structures. We found that the Roper-like resonances i
The mass spectra and wave functions of both $1S$ and $2S$ state heavy pseudoscalar ($P$) and vector ($V$) mesons are analyzed within the light-front quark model. Important empirical constraints employed in our analysis of the mass spectra and wave functions are the experimental mass-gap relation, $\mathrm{\ensuremath{\Delta}}{M}_{P}>\mathrm{\ensuremath{\Delta}}{M}_{V}$, where $\mathrm{\ensuremath{\Delta}}{M}_{P(V)}={M}_{P(V)}^{2S}\ensuremath{-}{M}_{P(V)}^{1S}$ and the hierarchy of the decay c
We study the three-body decay of the newly observed bottom baryon ${\mathrm{\ensuremath{\Lambda}}}_{b}^{*}(6072)$ by LHCb; ${\mathrm{\ensuremath{\Lambda}}}_{b}^{*}(6072)\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\pi}\ensuremath{\pi}$. Its mass about 500 MeV above the ground state ${\mathrm{\ensuremath{\Lambda}}}_{b}$ and a broad width imply that the state could be an analogue of the Roper resonance of the nucleon $N(1440)$. In terms of sequential processes going throu
Three-body decay of charmed baryons ${\ensuremath{\Lambda}}_{c}^{*}(2595)$ and ${\ensuremath{\Lambda}}_{c}^{*}(2625)$ into ${\ensuremath{\Lambda}}_{c}\ensuremath{\pi}\ensuremath{\pi}$ are studied with effective Lagrangians in which the coupling constants are extracted from the nonrelativistic quark model. We take into account sequential processes going through ${\ensuremath{\Sigma}}_{c}(2455)$ and ${\ensuremath{\Sigma}}_{c}^{*}(2520)$ in intermediate states. The total decay widths are sensitive
The issue of resulting in the same physical observables with different current components, in particular from the minus current, has been challenging in the light-front quark model (LFQM) even for the computation of the two-point functions such as meson decay constants. At the level of one-body current matrix element computation, we show the uniqueness of pseudoscalar and vector meson decay constants using all available components including the minus component of the current in the LFQM consiste
In the light-front quark model (LFQM) amenable to the simultaneous study of both the mass spectroscopy and the wave function related observables, we examine the decay constants and distribution amplitudes (DAs) up to the twist-4. The analysis of the heavy pseudoscalar mesons is carried out both in the $1S$ and $2S$ states. This investigation involves calculating the local and nonlocal matrix elements $⟨0|\overline{q}\mathrm{\ensuremath{\Gamma}}q|P⟩$ using three distinct current operators $\mathr
We investigate the in-medium properties of pseudoscalar and vector mesons with the light-light and heavy-light quarks in a light-front quark model, using the in-medium quark properties computed by the quark-meson coupling model. Both models are constructed on an equal footing with the constituent quark degree of freedom. Here, we particularly focus on the weak decay constants and distribution amplitudes (DAs) of the mesons in symmetric nuclear matter. We find that the weak decay constants decrea
We investigate the structure of ground-state heavy mesons within the light-front quark model, utilizing wave functions derived from the single Gaussian ansatz (SGA) and the Gaussian expansion method (GEM). By performing a <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msup><a:mi>χ</a:mi><a:mn>2</a:mn></a:msup></a:math> fit to static properties such as mass spectra and decay constants, we determine the model parameters for each approach. We then compare the impacts of bo
We investigate the three-body decays of ${\mathrm{\ensuremath{\Lambda}}}_{c}^{*}(2595)$ and ${\mathrm{\ensuremath{\Lambda}}}_{c}^{*}(2625)$ into ${\mathrm{\ensuremath{\Lambda}}}_{c}\ensuremath{\pi}\ensuremath{\pi}$ by including a direct process going through the two-pion coupling of ${\mathrm{\ensuremath{\Lambda}}}_{c}^{*}{\mathrm{\ensuremath{\Lambda}}}_{c}\ensuremath{\pi}\ensuremath{\pi}$ in addition to the sequential processes going through ${\mathrm{\ensuremath{\Sigma}}}_{c}(2455)$ and ${\mat
We study three-body decays of ${\mathrm{\ensuremath{\Lambda}}}_{c}^{*}(2765)\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Lambda}}}_{c}^{+}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ by using effective Lagrangians in a nonrelativistic framework. We consider the sequential decays through ${\mathrm{\ensuremath{\Sigma}}}_{c}(2455)\ensuremath{\pi}$ and ${\mathrm{\ensuremath{\Sigma}}}_{c}^{*}(2520)\ensuremath{\pi}$ in intermediate states which are dominant contributions. The coupling c
In this study, we present a comprehensive analysis of decay constants and chiral-even and chiral-odd distribution amplitudes (DAs) up to twist 4 for the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>ρ</a:mi></a:math> meson in the standard light-front quark model (LFQM) based on the Bakamjian-Thomas (BT) construction. For the <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>ρ</c:mi></c:math> meson, which possesses both longitudinal (<e:math
We explore the modifications of the hadron structure in a nuclear medium, focusing on the spacelike electromagnetic form factors (EMFFs) of light and heavy-light pseudoscalar mesons. By combining the light-front quark model with the quark-meson coupling model, which reasonably reproduces EMFFs in free space and the saturation properties of nuclear matter, respectively, we systematically analyze the in-medium EMFFs and charge radii of mesons with various quark flavors. Our findings show that the
The mass spectra and wave functions of both $1S$ and $2S$ state heavy pseudoscalar ($P$) and vector ($V$) mesons are analyzed within the light-front quark model. Important empirical constraints employed in our analysis of the mass spectra and wave functions are the experimental mass-gap relation, $ΔM_P > ΔM_V$, where $ΔM_{P(V)}=M^{2S}_{P(V)}-M^{1S}_{P(V)}$ and the hierarchy of the decay constants, $f_{1S}>f_{2S}$, between $1S$ and $2S$ meson states. We maintain the orthogonality of the tri
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