Bo Liu
Measurements of the X(3872) mass, $ψ(2S)$ production cross-section and $χ_{c2}/χ_{c1}$ production ratio using around 35$\rm pb^{-1}$ of pp collision data at $\sqrt{s}$ = 7 TeV during the 2010 LHC running period with the LHCb detector are presented.
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LHCb has productive studies of quarkonia and $b$-hadrons which provide essential inputs to study quantum chromodynamics (QCD). In this proceeding, seven recent results are reported: the observation of a new excited $Ξ_b^0$ resonance in $Ξ_b^- π^+$ final states, the new excited $B_s^0$ state is observed in $B^+ K^-$ mass spectrum, the first observation of suppressed semileptonic $B_s^0 \rightarrow K^- μ^+ ν_μ$ decay, the first observation of the decay $B^0 \rightarrow D^0 \bar{D}^0 K^+ π^-$, the first observation of the Cabibbo-suppressed decay $Λ_b^0 \rightarrow χ_{c1} p π^-$, the first observ…
Measurements of coherent charmonium production cross sections together with their ratio in ultra-peripheral PbPb collisions are studied at a nucleon-nucleon centre-of-mass energy of $5.02\,\mathrm{TeV}$, the differential cross-sections are measured as a function of rapidity and transverse momentum, separately. The photo-production of \jpsi mesons at low transverse momentum is studied in peripheral PbPb collisions, which confirms coherent \jpsi production in hadronic collisions. These latest results significantly improve previous measurements and are compared with some theoretical predictions.
Measurements of quarkonia production in ultra-peripheral heavy-ion collisions are of important value to study photon-photon and photon-nucleus interactions, the partonic structure of nuclei, and mechanisms of vector-meson production. LHCb has studied both coherent $J/ψ$ and $ψ(2S)$ mesons in ultra-peripheral collisions using PbPb data at forward rapidity with the highest precision currently accessible. In addition, measurements of $Z$ production in $p$Pb collisions provide new constraints on the partonic structure of nucleons bound inside nuclei. Here will present these measurements of quarkon…
The production of $J/ψ$ and $Υ$ mesons decaying into dimuon final state is studied at the LHCb experiment, with rapidity in the range of (1.5, 4.0) or (-5.0, -2.5) in proton-lead collisions at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{NN}}$ = 5 TeV, based on a data sample corresponding to an integrated luminosity of 1.6 /fb. The nuclear modification factor and forward-backward production ratio are determined for prompt $J/ψ$, $J/ψ$ from b-hadron decay and $Υ(1S)$ mesons in study of the cold nuclear matter effects.
The cross-sections of coherent \jpsi and \psitwos production in ultra-peripheral PbPb collisions at a nucleon-nucleon center-of-mass energy of $5.02\,\mathrm{TeV}$ are measured using a data sample collected in 2018 at $\lhcb$, and the differential cross-sections are measured separately as a function of transverse momentum and rapidity. The photo-production of \jpsi mesons at low transverse momentum is studied in peripheral PbPb collisions, \jpsi candidates are reconstructed through the prompt decay into \mumu in the rapidity region of $2.0<y<4.5$. These results significantly improve previous m…
The LHCb experiment has a broad and varied physics programme, extending far beyond its core set of flavour physics measurements. This contribution summarises recent electroweak scale measurements and searches for exotic states in the dimuon final state.
Recent results on studies of exotic hadrons at the LHCb experiment are summarised. These are the observation of new resonances decaying to J/$ψK^{+}$ and J/$ψϕ$, evidence of a J/$ψΛ$ structure and observation of excited $Ξ^{-}$ states in the $Ξ_{b}^{-}\to J/ψΛK^{-}$ decay and the study of $B_{s}^{0}\to J/ψπ^{+}π^{-}K^{+}K^{-}$ decays.
Born-Oppenheimer EFT: a unified description of ordinary and exotic quarkonia
本文提出Born-Oppenheimer EFT统一描述普通和奇异夸克onium，通过QCD非相对论展开和格点QCD输入，应用于四夸克、五夸克及夸克onium杂化态并评估阈值效应。
We investigate the properties of mesons with the exotic J^PC = 1^-+ quantum numbers. Starting out from the light-quark domain, where the π_1 states are used as references, we predict the masses of analogous quarkonia for c\bar{c} and b\bar{b} configurations. We employ a covariant Dyson-Schwinger-Bethe-Salpeter-equation approach with a rainbow-ladder truncated model of quantum chromodynamics.
QCD, Electroweak Physics, and Searches for Exotic Signatures in the Forward Region at LHCb
本文介绍了LHCb前向谱仪的独特相空间覆盖，展示了其在电弱、QCD及寻找超出标准模型奇异特征物理方面的精选互补性研究成果。
We present a summary of new experimental results on the status of the charm spectroscopy using inclusive approaches and Dalitz plot analyses of $B$ and $B_s$ decays. We also report on a new determination of the $X(3872)$ quantum numbers.
A review of the experimental status of purely leptonic ${B^0_{[s]}\to\ell^+\ell^-}$ decays is given and the new analysis of ${B^0_{[s]}\toμ^+μ^-}$ observables with the LHCb experiment is presented. The new results are the most precise single experiment measurements of the quantities to date and are consistent with the Standard Model. However, they also match the recent anomalies found in $b\to s\ell\ell$ transitions excellently.
The LHCb experiment is designed to study the decays and properties of heavy flavoured hadrons produced in the forward region from proton-proton collisions at the CERN Large Hadron Collider. During Run 1, it has recorded the world's largest data sample of beauty and charm hadrons, enabling precise studies into the spectroscopy of such particles, including discoveries of new states and measurements of their masses, widths and quantum numbers. An overview of recent LHCb results in the area of exotic hadron spectroscopy is presented, focussing on the discovery of the first pentaquark states in the…
We report on the latest direct searches for light exotics at LHCb, conducted during Run I of LHC. This proceedings are divided into two sections, the first part will cover the search for the lepton number violating decay ${B}\rightarrow {π^{+}μ^{-}μ^{-}}$ while the second part will cover the search for a low mass dark boson in the decay $B^0 \rightarrow K^{*0}χ$, with $χ\rightarrow μ^+μ^-$ and $K^{*0} \rightarrow K^+π^-$. The data used in these searches correspond to integrated luminosities of 1.0 and $2.0$ fb$^{-1}$ collected in $pp$ collisions at centre of mass energies of $\sqrt{s}=7$ and 8…
QCD, electroweak physics, and searches for exotic signatures in the forward region at LHCb
LHCb探测器通过其前方覆盖范围在多种物理分析中表现出竞争力。本文报告了利用重味喷注的互补测量、顶夸克和W玻色子的电弱测量，以及寻找新物理状态如轴子类似粒子、重中微子和B介子到多muon最终态的搜索。
Exotic Hadrons at LHCb
本文综述了LHCb探测器五年间在奇特强子谱学上的重大发现及相关唯象学解释，并探讨了2024年升级后该项目在奇特强子物理领域的研究潜力。
These proceedings present the LHCb results on Majorana neutrino searches and direct production of exotic particles using the data collected during Run I of LHC. For the former, Majorana neutrinos are searched for both on-shell and off-shell in $B$ and $D$ decays to final states with two same-sign muons. For the latter, different types of new particles are studied profiting the unique coverage of LHCb with respect to other detectors.
This talk presents a review of recent results for quarkonium production at the LHC from ATLAS, CMS, LHCb, and ALICE. Production cross sections for $J/ψ$, $ψ(2S)$, and $Υ(mS)$, and production ratios for $χ_{c,bJ}$ are found to be in good agreement with predictions from non-relativistic QCD. In contrast, spin-alignment (polarization) measurements seem to disagree with all theoretical predictions. Some other production channels useful for investigating quarkonium hadroproduction mechanisms are also considered.
I will report on the recent LHCb results on the evidence for the decay $X(3872)\rightarrowψ(2S) γ$, and on the improved measurement of the mass and width of the $Z(4430)^-$, the determination of its quantum numbers and the observation of its resonant character.
The LHCb experiment is designed to study properties and decays of heavy flavored hadrons produced from $pp$ collisions at the LHC. During Run~1, it has recorded the world's largest data sample of beauty and charm hadrons, enabling precision spectroscopy studies of such particles. Several important results obtained by LHCb, such as the discovery of the first pentaquark states and the first unambiguous determination of the $Z_c(4430)^-$ as an exotic state, have dramatically increased the interest on spectroscopy of heavy hadrons. An overview of the latest LHCb results on the subject, including t…
We advocate for the construction of a new detector element at the LHCb experiment, designed to search for displaced decays of beyond standard model long-lived particles, taking advantage of a large shielded space in the LHCb cavern that is expected to soon become available. We discuss the general features and putative capabilities of such an experiment, as well as its various advantages and complementarities with respect to the existing LHC experiments and proposals such as SHiP and MATHUSLA. For two well-motivated beyond Standard Model benchmark scenarios -- Higgs decay to dark photons and $B…
The beauty hadron decays is unique laboratory to study charmonium and charmonium-like states, such as the $χ_{c1}(3872)$ meson, other exotic states and the tensor D-wave $ψ_2(3823$) states. However the nature of many exotic charmonium-like candidates are still unknown. The most recent LHCb results related to b-hadron decays to charmonium states and obtained using large data samples collected during the Run 1 and Run 2 periods are presented. This includes the most precise determination of the mass and width of the $χ_{c1}(3872)$ state using the $B^{+} \to J/ψπ^{+}π^{-}K^{+}$ decays, observation…
The production of c c_bar and b b_bar is studied in pp collisions at sqrt(s) = 7 TeV with the LHCb detector. The results of these measurements are compared with different theoretical models. Results and prospects are also shown for exotics: the mass measurement of the X(3872) and the search of the X(4140). Most of the presented results are based on the 2010 LHCb dataset (35 pb-1).
The rapidity dependent transverse momentum spectra of heavy quarkonia (J/psi and Upsilon mesons) produced in small collision systems such as proton-proton (pp) and proton-lead (p-Pb) collisions at center-of-mass energy (per nucleon pair) 5-13 TeV are described by a two-component statistical model which is based on the Tsallis statistics and inverse power-law. The experimental data measured by the LHCb Collaboration at the Large Hadron Collider (LHC) are well fitted by the model results. The related parameters are obtained and the dependences of parameters on rapidity are analyzed.
The last decade of hadron spectroscopy has unveiled a wealth of states that do not have the properties expected of particles composed of two or three valence quarks. Among the most intriguing of these exotics is the $χ_{c1}(3872)$, which various models attempt to describe as a hadronic molecule, a compact tetraquark, an unexpected charmonium state, or their mixtures. To date, most experimental studies of the $χ_{c1}(3872)$ have focused on its production through $B$ meson decays. Heavy ion collisions, as well as high multiplicity $pp$ collisions, offer a new window on the properties of this poo…
The latest results obtained by the LHCb collaboration from proton-lead and proton-gas fixed-target collisions are presented. Results related to charm and beauty flavour hadron and quarkonia production in proton-lead collisions, being clean probes for Cold Nuclear Matter effects, are compatible to predictions based on initial-state effects. Indications of significant final-state effects in excited $Υ(nS)$ resonances production are reported. The first cross-section measurement of $c\bar{c}$ and antiproton production in fixed-target proton-helium collisions at 100 GeV energy scale are also presen…
Heavy hybrid decays to quarkonia
基于非相对论有效场论框架，计算了重夸克偶素杂化态到常规重夸克偶素的半举衰变率，在领头阶和次领头阶更新了结果，并与实验数据进行了比较。
The LHCb experiment offers the unique opportunity to study heavy-ion interactions in the forward region (2 <eta< 5), in a kinematic domain complementary to the other 3 large experiments at the LHC. The detector has excellent capabilities for reconstructing quarkonia and open charm states, including baryons, down to zero $p_T$. It can separate the prompt and displaced charm components. In $p$Pb collisions, both forward and backward rapidities are covered thanks to the possibility of beam reversal. Results include measurements of the nuclear modification factor and forward-backward ratio for cha…
Inclusive production of $ΥJ/ψ$ pair in proton-proton interation at LHCb is considered. This process is forbidden at leading order of perturbation theory, so such channels as double parton scattering, $χ_bχ_c$ pair production with subsequent radiative decays of $P$-wave quarkonia, contributions of color-octet states, and NLO corrections are studied in details. For all these channels we present theoretical predictions of total cross sections at LHCb and distributions over different kinematical variables. According to presented in the paper results, double parton interaction gives main contributi…
Heavy quarkonia and new hadrons with two heavy quarks
本文教学式综述重夸克偶素及含两个重夸克的奇特强子，重点讨论违背夸克模型的XYZ态及其对非微扰QCD和夸克禁闭研究的挑战。
Measurements of heavy flavor production and decay have featured prominently in the early results from the four large LHC experiments: ALICE, ATLAS, CMS, and LHCb. These results provide tests of QCD models in a new energy region and point the way toward future measurements of CP violation and searches for new physics. An overview of open heavy flavor studies is presented here, focusing on how the new measurements extend our knowledge of this area of physics. Heavy quarkonia states at the LHC are summarized in other proceedings of this conference. I also discuss briefly how heavy flavor measurem…
Inspired by $P_c(4380)$ and $P_c(4450)$ recently observed by LHCb, a QCD sum rule investigation is performed, by which they can be identified as exotic hidden-charm pentaquarks composed of an anti-charmed meson and a charmed baryon. Our results suggest that $P_c(4380)$ and $P_c(4450)$ have quantum numbers $J^P=3/2^-$ and $5/2^+$, respectively. Furthermore, two extra hidden-charm pentaqurks with configurations $\bar{D}Σ_c^*$ and $\bar{D}^*Σ_c^*$ are predicted, which have spin-parity quantum numbers $J^P=3/2^-$ and $J^P=5/2^+$, respectively. As an important extension, the mass predictions of hid…
Predictions for $h_c$ and $h_b$ production at the LHC
本文利用重夸克对称性在NRQCD框架下预言LHC上h_c和h_b的产生截面与横动量分布，并通过与LHCb数据比较表明修正NRQCD能更好地描述实验，从而有助于区分夸克偶素产生模型。
With appropriate interpolating currents the mass spectra of $0^{+-}$, $1^{-+}$, and $2^{+-}$ oddballs are studied in the framework of QCD sum rules (QCDSR). We find there exits one stable $0^{+-}$ oddball with mass of $4.57 \pm 0.13 \, \text{GeV}$, and one stable $2^{+-}$ oddball with mass of $6.06 \pm 0.13 \, \text{GeV}$, whereas, no stable $1^{-+}$ oddball shows up. The possible production and decay modes of these glueballs with unconventional quantum numbers are analyzed, which are hopefully measurable in either BELLEII, PANDA, Super-B or LHCb experiments.
The BESIII and the LHCb became the leading experiments in the study of the exotic states after the Belle and BaBar experiments finished their data taking in the first decade of this century. We review the progress in the study of the XYZ states at BESIII and LHCb experiments with their unique data samples in $e^+e^-$ annihilation at center-of-mass energies of 3.8--4.6~GeV and in pp collision at center-of-mass energies 7, 8, and 13~TeV, respectively. With these data samples, we have deepened our understanding of the most famous charmonium-like states X(3872), Y(4260), Z_c(3900), and Z_c(4430), …
In this paper we describe the history of the LHCb experiment over the last three decades, and its remarkable successes and achievements. LHCb was conceived primarily as a b-physics experiment, dedicated to CP violation studies and measurements of very rare b decays, however the tremendous potential for c-physics was also clear. At first data taking, the versatility of the experiment as a general-purpose detector in the forward region also became evident, with measurements achievable such as electroweak physics, jets and new particle searches in open states. These were facilitated by the excell…
We outline the case for heavy-ion-physics studies using the multi-TeV lead LHC beams in the fixed-target mode. After a brief contextual reminder, we detail the possible contributions of AFTER@LHC to heavy-ion physics with a specific emphasis on quarkonia. We then present performance simulations for a selection of observables. These show that $Υ(nS)$, $J/ψ$ and $ψ(2S)$ production in heavy-ion collisions can be studied in new energy and rapidity domains with the LHCb and ALICE detectors. We also discuss the relevance to analyse the Drell-Yan pair production in asymmetric nucleus-nucleus collisio…
Possible signal of an exotic $I=1$, $J=2$ state in the $B \to D^{*-}D^+K^+$ reaction
本文研究 $B \to D^{*-}D^+K^+$ 反应，将 LHCb 在约 2834 MeV 处的峰解释为 $J^P=2^+$ 奇特态，并提出通过角质量分布及干涉项判别自旋。
Extraction of Effective Parameters from Transverse Momentum Spectra of Heavy Quarkonia in Proton-Proton Collisions at the LHC
本文通过分析LHC碰撞中重夸克onium的横动量谱，提取有效弦张力和有效温度，并探讨其在小碰撞系统中的初始有效温度作用。
The field of exotic spectroscopy is extremely rich and productive. Several observations and searches for pentaquark states have been performed in the last 4 years, starting from the LHCb observation in 2015. This is still quite a recent discovery, and possibly the beginning of a new era in both observation of new states and understanding of the QCD binding mechanisms. The most recent results from LHCb and Belle are presented regarding measurements and searches for charm, strange and beauty pentaquarks, along with an introduction on phenomenology of multiquark states.
Hadronisation of in-medium $c\bar c$ pairs to the exotic $X(3872)$
研究夸克-胶子等离子体中$c\bar c$夸克分离对奇异$X(3872)$强子产额的影响，通过费米黄金定则关联真空与介质波函数内积，解释LHC实验数据。
In the $B^+\to D^+ D^-K^+$ decay, LHCb has reported the observation of the open-charm exotic states $X_{0,1}^0\equiv X_{0,1}(2900)^0$ with four different quark flavors~$(ud\bar s \bar c)$, where the subscripts (0,1) denote the spins. To confirm the discovery, we propose $Λ_b\to Σ_c^{0(++)} X_{0,1}^{\prime\,0(--)}$ in the final state interaction, where $X_{0,1}^{\prime\,0(--)}$ with $s u\bar d \bar c$ ($ds\bar u \bar c$) are the new $X_{0,1}$-like exotic states. More specifically, $Λ_c^+D_s^-$ in $Λ_b\to Λ_c^+D_s^-$ are transformed as $Σ_c^{0(++)} X_{0,1}^{\prime\,0(--)}$, by exchanging $π^{+(-…
The LHCb Collaboration has reported resonant activity in the channel $D^+ K^-$, identifying two components: $X_0(2900)$ with $J^P = 0^+$ at $2866 {\pm} 7$ MeV, $Γ_0=57{\pm} 13$ MeV and $X_1(2900)$ with $J^P = 1^-$ at $2904 {\pm} 7$ MeV, $Γ_1=110{\pm} 12$ MeV. We interpret the $X_0(2900)$ component as a $cs \bar u\bar d$ isosinglet compact tetraquark, calculating its mass to be $2863 {\pm} 12$ MeV. This is the first exotic hadron with open heavy flavor. The analogous $bs\bar u\bar d$ tetraquark is predicted at $6213 {\pm} 12$ MeV. We discuss possible interpretations of the heavier and wider $X_…
Is the LHCb $P_c(4312)^+$ plausible in the GlueX $γp\to J/ψp$ total cross sections ?
本文通过拟合GlueX实验的$γp\to J/ψp$总截面数据寻找LHCb观测到的奇特$P_c(4312)^+$态，发现$S$波共振与非共振背景的相消干涉能解释数据中的凹陷结构，并讨论了模型局限与统计量需求。
Motivated by a recent successful dynamical explanation for the newly observed fully-charm structure $X(6900)$ in the mass spectrum of di-$J/ψ$ by LHCb [J.~Z.~Wang \textit{et al.} arXiv:2008.07430], in this work, we extend the same dynamical rescattering mechanism to predict the line shape of more potential fully-heavy structures in the invariant mass spectrum of $J/ψψ(3686)$, $J/ψψ(3770)$, $ψ(3686) ψ(3686)$, and $J/ψΥ(1S)$ at high energy proton-proton collisions, whose verification in experiments should be helpful to further clarify the nature of $X(6900)$. The above final states of vector hea…
Exotic resonant structures found in $Λ^0_b$ and $\overline{B}^0$ decays into charmonium in the LHCb experiment are discussed. Examination of the $J/ψp$ system in $Λ^0_b\to J/ψK^- p$ decays shows two states each of which must be composed of $uudc\overline{c}$ quarks, and thus are called charmonium pentaquarks. Their masses are $4380\pm 8\pm 29$~MeV and $4449.8\pm 1.7\pm 2.5$~MeV, and their corresponding widths ($Γ$) are $205\pm 18\pm 86$ MeV, and $39\pm 5\pm 19$ MeV. The preferred $J^P$ assignments are of opposite parity, with one state having spin 3/2 and the other 5/2. Models of internal bind…
We report on the inclusive production cross sections of J/$ψ$, $ψ$(2S), $Υ$(1S), $Υ$(2S) and $Υ$(3S), measured at forward rapidity with the ALICE detector in pp collisions at a center-of-mass energy $\sqrt{s}=8$ TeV. The analysis is based on data collected at the LHC and corresponds to an integrated luminosity of 1.28 pb$^{-1}$. Quarkonia are reconstructed in the dimuon-decay channel. The differential production cross sections are measured as a function of the transverse momentum $p_{\rm T}$ and rapidity $y$, over the $p_{\rm T}$ ranges $0<p_{\rm T}<20$ GeV/$c$ for J/$ψ$, $0<p_{\rm T}<12$ GeV/…
The search for hybrid mesons and the detailed study of their spectrum is the primary goal of the GlueX Experiment in Hall D at Jefferson Lab. The identification and study of hybrid mesons promises to provide unique insight into gluonic degrees of freedom in QCD and the nature of confinement. The experiment combines an intense photon beam with linear polarization peaking around 9 GeV incident on a liquid hydrogen target with a nearly hermetic spectrometer, allowing for the comprehensive study of charged and neutral particle final states. The first phase of the experiment has recently concluded,…
The LHCb Collaboration at the Large Hadron Collider at CERN discovered two pentaquark states $P_c(4380)$ and $P_c(4450)$. These two hidden-charm states are interpreted as the loosely bound $Σ_c(2455)D^*$ and $Σ_c^*(2520)D^*$ molecular states in the boson exchange interaction model, which provides an explanation for why the experimental width of $P_c(4450)$ is much narrower than that of $P_c(4380)$. The discovery of the new resonances $P_c(4380)$ and $P_c(4450)$, indeed, opens a new page for hadron physics. The partners of $P_c(4380)$ and $P_c(4450)$ should be pursued in future experiments.
Two iso-singlet hadron states $X_0(2900)$ and $X_1(2900)$ with $J=0$ and 1 respectively, discovered by the LHCb collaboration in 2020, were identified as molecular bound states of $\bar D^*K^*$. Recently two structures $T^a_{cs0}(2900)^0$ and $T^a_{cs0}(2900)^{++}$ have been observed at the hadron spectra, one would suspect if they also are molecular states of $D^*$ and $K^*$. As long as they were of the molecular structures of $D^*K^*$, the hadron states must be in an iso-vector, namely $T^a_{cs0}(2900)^0$ and $T^a_{cs0}(2900)^{++}$ were $I_3=-1, 1$ components of the iso-vector. If it is the …
Exotic hadrons associated with $b$-quark
本文综述了与 $b$ 夸克相关的奇特强子（如 $Z_b$、$X_b$、$Y_b$ 态）的实验和理论研究，强调了重底夸克在理论计算中的优势，并介绍了 Belle、Belle II 和 LHCb 实验的最新成果。
Used in the fixed-target mode, the multi-TeV LHC proton and lead beams allow for studies of heavy-flavour hadroproduction with unprecedented precision at backward rapidities - far negative Feyman-x - using conventional detection techniques. At the nominal LHC energies, quarkonia can be studies in detail in p+p, p+d and p+A collisions at sqrt(s_NN) ~ 115 GeV as well as in Pb+p and Pb+A collisions at sqrt(s_NN) ~ 72 GeV with luminosities roughly equivalent to that of the collider mode, i.e. up to 20 fb-1 yr-1 in p+p and p+d collisions, up to 0.6 fb-1 yr-1 in p+A collisions and up to 10 nb-1 yr-1…
Motivated by the very recent discovery of fully open-flavor exotic states $X_0(2900)$ and $X_1(2900)$ by the LHCb Collaboration, we study possible interpretations of these exotic states by QCD Sum Rules method. We have calculated mass and decay constant by traditional QCD Sum Rules analysis and Monte-Carlo based analysis. $X_0(2900)$ and $X_1(2900)$ are studied in molecular and diquark-antidiquark tetraquark pictures, respectively. Obtained mass results agree well with the masses observed in the experiment. We also made a Monte-Carlo based analysis within QCD Sum Rules for the mass and decay c…
Benchmark calculations of fully heavy compact and molecular tetraquark states
使用三种夸克势模型计算S波全重四夸克态质量谱，结合分子型与紧凑型空间关联，发现多个共振态及奇特C宇称零宽度态，部分共振态为实验观测粒子的良好候选者。
Hadron spectroscopy provides direct physical measurements that shed light on the non-perturbative behavior of quantum chromodynamics (QCD). In particular, various exotic hadrons such as the newly observed $T_{cc}^+$ by the LHCb collaboration, offer unique insights on the QCD dynamics in hadron structures. In this letter, we demonstrate how heavy ion collisions can serve as a powerful venue for hadron spectroscopy study of doubly charmed exotic hadrons by virtue of the extremely charm-rich environment created in such collisions. The yields of $T_{cc}^+$ as well as its potential isospin partners…
Based on the hypothesis that the $X(3872)$ exotic hadron is a mixture of $χ_{c1}(2P)$ and other states and that its prompt hadroproduction predominately proceeds via its $χ_{c1}(2P)$ component, we calculate the prompt-$X(3872)$ polarization at the CERN LHC through next-to-leading order in $α_s$ within the factorization formalism of nonrelativistic QCD, including both the color-singlet $^3\!P_1^{[1]}$ and color-octet $^3\!S_1^{[8]}$ $c\bar c$ Fock states. We also consider the polarization of the $J/ψ$ produced by the subsequent $X(3872)$ decay. We predict that, under ATLAS, CMS, and LHCb experi…
In this work, we treat the newly observed doubly charmed four-quark state $ T_{cc}^{+}$ as an axial-vector tetraquark with content $cc\overline{u} \overline{d}$, and calculate its spectroscopic parameters and width. The mass and current coupling of the tetraquark $T_{cc}^{+}$ are found by means of the QCD two-point sum rule method by taking into account quark, gluon and mixed condensates up to dimension $10$. The width of the $T_{cc}^{+}$ is evaluated using partial widths of decay processes $T_{cc}^{+} \to \widetilde{ T}π^{0}$ and $T_{cc}^{+} \to T_{cc;\overline{u}\overline{u}}^{0}π^{+}$ , whe…
The LHCb Collaboration announced two pentaquark-like structures in the $J/ψp$ invariant mass distribution. We show that the current information on the narrow structure at 4.45 GeV is compatible with kinematical effects of the rescattering from $χ_{c1} p$ to $J/ψp$: First, it is located exactly at the $χ_{c1} p$ threshold. Second, the mass of the four-star well-established $Λ(1890)$ is such that a leading Landau singularity from a triangle diagram can coincidentally appear at the $χ_{c1} p$ threshold, and third, there is a narrow structure at the $χ_{c1}\,p$ threshold but not at the $χ_{c0} p$ …
Inspired by the recent observation of $χ_{c0}(3930)$, $X(4685)$ and $X(4630)$ by the LHCb Collaboration and some exotic resonances such as $X(4350)$, $X(4500)$, etc. by several experiment collaborations, the $cs\bar{c}\bar{s}$ tetraquark systems with $IJ^{P}=00^+$, $01^+$ and $02^+$ are systematically investigated in the framework of the quark delocalization color screening model(QDCSM). Two structures, the meson-meson and diquark-antidiquark structures, as well as the channel-coupling of all channels of these two configurations are considered in this work. The numerical results indicate that …
Very recently, the LHCb Collaboration reported a fully charmed tetraquark state $X(6900)$ in the invariant mass spectrum of $J/ψ$ pairs. If one $J/ψ$ meson is replaced with a fully charmed baryon, we obtain a fully charmed pentaquark candidate. In this work, we perform a systematic study on the mass spectra of the S-wave fully heavy pentaquark $QQQQ\bar{Q}$ in the framework of the chromomagnetic interaction model. Based on our results in two different schemes, we further investigate the decay behaviors for them. We hope that our study will be helpful in searching for such types of exotic penta…
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