There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

비만아 부모의 돌봄 경험: q 방법론

A golden age for heavy-quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the B-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations at BESIII, the LHC, RHIC, FAIR, the Super Flavor and/or Tau-Charm factories, JLab, the ILC, and beyond. The list of newly found conventional states expanded to include h(c)(1P), chi(c2)(2P), B-c(+), and eta(b)(1S). In addition, the unexpected and still-fascinating X(3872) has been joined by more than a dozen other charmonium- and bottomonium-like "XYZ" states that appear to lie outside the quark model. Many of these still need experimental confirmation. The plethora of new states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of c (c) over bar, b (b) over bar, and b (c) over bar bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. Lattice QCD has grown from a tool with computational possibilities to an industrial-strength effort now dependent more on insight and innovation than pure computational power. New effective field theories for the description of quarkonium in different regimes have been developed and brought to a high degree of sophistication, thus enabling precise and solid theoretical predictions. Many expected decays and transitions have either been measured with precision or for the first time, but the confusing patterns of decays, both above and below open-flavor thresholds, endure and have deepened. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.

/pdf/heavy-quarkonium-progress-puzzles-and-opportunities-2tru0l8jyp.pdf

Heavy quarkonium: progress, puzzles, and opportunities

The newly observed $\Omega_c(3327)$ gives us a good chance to construct the $\Omega_c$ charmed baryon family. In this work, we carry out the mass spectrum analysis by a non-relativistic potential model using Gaussian Expansion Method, and the study of its two-body Okubo-Zweig-Iizuka allowed strong decay behavior. Our results imply that the $\Omega_c(3327)$ is good candidate of $\Omega_c(1D)$ state with $J^P=5/2^+$. We also predict the spectroscopy behavior of other $\Omega_c(1D)$ states, which may provide further clues to their search. 

Newly observed 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi mathvariant="normal">Ω</mml:mi><mml:mi>c</mml:mi></mml:msub><mml:mo stretchy="false">(</mml:mo><mml:mn>3327</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math>
: A good candidate for a 
<mm

The recently discovered $\eta_1(1855)$ and the previously observed $\pi_1(1600)$ present a valuable opportunity for the investigation of the $J^{P(C)}=1^{-(+)}$ light hybrid nonet. In this study, we employ a semirelativistic quark potential model to examine the masses of the $J^{P(C)}=1^{-(+)}$ light hybrid states. The static potential, which portrays the confinement force between the quark-antiquark pair in a hybrid system, is borrowed from the SU$(3)$ lattice gauge theory. Additionally, we utilize a constituent gluon model to analyze the strong decay characteristics of these light $1^{-+}$ hybrids. Our findings suggest that the $\pi_1(1600)$ and $\eta_1(1855)$ could be potential candidates for $1^{-+}$ $(u\bar{u}-d\bar{d})g/\sqrt{2}$ and $s\bar{s}g$ hybrids, respectively. To ensure comprehensiveness, we also investigate the isospin partners of the $\pi_1(1600)$ and $\eta_1(1855)$ within the $1^{-(+)}$ nonet, specifically, the $(u\bar{u}+d\bar{d})g/\sqrt{2}$ and $s\bar{q}g$ ($q=u$ and $d$ quarks) states. We propose some potential decay channels which could be explored in experimental settings to detect these undiscovered states.

Constructing the $J^{P(C)}=1^{-(+)}$ light flavor hybrid nonet with the newly observed $\eta_1(1855)$

By treating the recent evidence of a new bottomonium-like structure $\Upsilon(10753)$ reported by Belle as the missing $\Upsilon_1(3D)$ bottomonium state, we study its hidden-bottom hadronic decays with a $\eta^{(\prime)}$ or $\omega$ emission, which include $\Upsilon(10753)\to\Upsilon(1S)\eta^{(\prime)}$, $\Upsilon(10753)\to h_{b}(1P)\eta$ and $\Upsilon(10753)\to\chi_{bJ}\omega$ ($J$=0,1,2) processes. Since $\Upsilon(10753)$ is above the $B\bar{B}$ threshold, the coupled-channel effect cannot be ignored, thus, when calculating partial decay widths of these $\Upsilon(10753)$ hidden-bottom decays, we apply the hadronic loop mechanism. Our result shows that these discussed decay processes own considerable branching fractions with the order of magnitude of $10^{-4}\sim 10^{-3}$, which can be accessible at Belle II and other future experiments.

Hidden-bottom hadronic decays of $\Upsilon(10753)$ with a $\eta^{(\prime)}$ or $\omega$ emission

We calculate the form factors of the $\Lambda_b\to\Lambda_c(2625)$ and $\Xi_b\to\Xi_c(2815)$ transitions, and additionally evaluate the corresponding semileptonic decays and the color-allowed two-body nonleptonic decays. In order to obtain the concerned form factors, we use the three-body light-front quark model with the support from baryon spectroscopy. In this work, as important physical inputs, the spatial wave functions of concerned baryons are obtained by the Gaussian expansion method with a semirelativistic potential model. For the semileptonic processes, the branching ratios of the electron and muon channels can reach up to the order of magnitude of $1\%$, where our result $\mathcal{B}(\Lambda_b^0\to\Lambda_c^+(2625)\mu^-\nu_{\mu})=(1.641\pm0.113)\%$ is consistent with the current experimental data. As for the nonleptonic processes, the decays to $\pi^-$, $\rho^-$, and $D_s^{(*)-}$ final states have considerable widths. These discussed decay modes could be accessible at the LHCb experiment.

Investigating the transition form factors of $\Lambda_b\to\Lambda_c(2625)$ and $\Xi_b\to\Xi_c(2815)$ and the corresponding weak decays with support from baryon spectroscopy

The decay process ${\mathrm{\ensuremath{\Xi}}}_{b}^{\ensuremath{-}}\ensuremath{\rightarrow}p{K}^{\ensuremath{-}}{K}^{\ensuremath{-}}$ is studied with the final-state interaction approach by considering the contributions from the $S$-wave meson-baryon interactions, and also the intermediate state $\mathrm{\ensuremath{\Lambda}}(1520)$ in the $D$-wave. The low-lying resonances $\mathrm{\ensuremath{\Lambda}}(1405)$ and $\mathrm{\ensuremath{\Lambda}}(1670)$ have significant contributions, which are both dynamically generated from the $S$-wave final-state interactions with isospin $I=0$. Furthermore, the $\mathrm{\ensuremath{\Lambda}}(1520)$ state also has important contributions from $D$-wave. With these resonances contributions, the experimental data of the lower $p{K}^{\ensuremath{-}}$ invariant mass distributions are well-described. We also discuss the contribution of another resonance in the $S$-wave with isospoin $I=1$, which cannot be ignored. Moreover, some of the branching fractions obtained for the corresponding decay channels are consistent with the experimental measurements. 

Study of the resonance contributions in the 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msubsup><mml:mi mathvariant="normal">Ξ</mml:mi><mml:mi>b</mml:mi><mml:mo>−</mml:mo></mml:msubsup><mml:mo stretchy="false">→</mml:mo><mml:mi>p</mml:mi><mml:msup><mml:mi>K</mml:m

Xiang Liu

Papers

Newly observed <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi mathvariant="normal">Ω</mml:mi><mml:mi>c</mml:mi></mml:msub><mml:mo stretchy="false">(</mml:mo><mml:mn>3327</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math> : A good candidate for a <mm

Constructing the $J^{P(C)}=1^{-(+)}$ light flavor hybrid nonet with the newly observed $\eta_1(1855)$

Hidden-bottom hadronic decays of $\Upsilon(10753)$ with a $\eta^{(\prime)}$ or $\omega$ emission

Investigating the transition form factors of $\Lambda_b\to\Lambda_c(2625)$ and $\Xi_b\to\Xi_c(2815)$ and the corresponding weak decays with support from baryon spectroscopy