Search

We study the Λ(1405) resonance with I (J P ) = 0(1/2−) in the context of the pentaquark hypothesis in the nuclear medium. To explore the influence of the nuclear medium on the physical parameters of Λ(1405), we propose a molecular-type structure involving admixtures of K − p and K ¯ 0 n , correlated with the nuclear matter density. Our analysis reveals a substantial shift in mass and residue, approximately 20% and 38%, respectively. These findings have significant implications for experimental researchers aiming to identify in-medium characteristics of hyperon resonances. [ABSTRACT FROM AUTHOR]

We study systematically magnetic moments of hiddden-bottom pentaquark states with quantum numbers J P = 1 2 ± , J P = 3 2 ± , and J P = 5 2 ± with molecular, diquark–diquark–antiquark, and diquark–triquark models. The numerical results show that magnetic moments are different within the same model according to same quantum numbers and spin-orbit couplings. The results are also different when different models are taken into account with the same angular momentum. The magnetic moments encode valuable information about inner structures. We believe that our results may be helpful for experimental studies. [ABSTRACT FROM AUTHOR]

In this work, the doubly-charm and doubly-bottom pentaquark molecular states D (∗) Σ c (∗) and B (∗) Σ b (∗) are studied via the QCD sum rules. Sixteen color singlet-singlet type currents with the definite isospin-spin-parity I J P are constructed to interpolate the corresponding hadronic states with the same quantum numbers. The masses and pole residues of those doubly-heavy pentaquark molecular states are calculated, the results show that their masses are all below the corresponding meson-baryon thresholds, which means that they are possible bound states, not resonant states, moreover, the possible decay channels for the doubly-charm molecular states are given. [ABSTRACT FROM AUTHOR]

The possibility of the existence of multiquark hadrons made of 4-quarks for mesons and 5-quarks for baryons was predicted by Gell-Mann [Phys. Lett. 8, 214 (1964)]. The renewed interest for the search for exotic pentaquark states was initiated by the paper by Diakonov, Petrov, and Polyakov [Z. Phys. A 359, 305 (1997)]. The 2003 experimental reports on the observation of Θ + pentaquark with u u d d s ̄ quark content created a great excitement and many following experiments have reported its observation [K. H. Hicks, Eur. Phys. J. H 37, 1 (2012)]. After high-statistics experiments at JLab, which did not confirm previous claims by the CLAS collaboration, the community concluded that the Θ + pentaquark either does not exist at all or has an extremely small cross-section, making it currently unobserved. There were different review papers on this subject, questioning the existence of Θ + or trying to explain the reasons why reaching a conclusion based on production experiments is challenging [M. Amaryan, Eur. Phys. J. Plus 137, 684 (2022)]. To address the challenge of minimal 3-body final states, a formation experiment with a projectile-kaon beam is proposed. In the following, we discuss how the Θ + could be observed in the K L p → Θ + → K + n reaction in the KLF experiment at JLab [M. Amaryan et al. [KLF Collaboration], arXiv:2008.08215 [nucl-ex]]. [ABSTRACT FROM AUTHOR]

Manganese catalysts that activate hydrogen peroxide carry out several different hydrocarbon oxidation reactions with high stereoselectivity. The commonly proposed mechanism for these reactions involves a key manganese(III)-hydroperoxo intermediate, which decays via O–O bond heterolysis to generate a Mn(V)–oxo species that institutes substrate oxidation. Due to the scarcity of characterized MnIII–hydroperoxo complexes, MnIII–alkylperoxo complexes are employed to understand factors that affect the mechanism of the O–O cleavage. Herein, we report a series of novel complexes, including two room-temperature-stable MnIII–alkylperoxo species, supported by a new amide-containing pentadentate ligand (6Medpaq5NO2). We use a combination of spectroscopic methods and density functional theory computations to probe the effects of the electronic changes in the ligand sphere trans to the hydroxo and alkylperoxo units to thermal stability and reactivity. The structural characterizations for both MnII(OTf)(6Medpaq5NO2) and [MnIII(OH)(6Medpaq5NO2)](OTf) were obtained via single-crystal X-ray crystallography. A perturbation to the ligand sphere allowed for a marked increase in reactivity towards an organic substrate, a modest change in the distribution of the O–O cleavage products from homolytic and heterolytic pathways, and little change in thermal stability. [ABSTRACT FROM AUTHOR]

The LHCb collaboration has recently announced the discovery of two hidden-charm pentaquark states with strange quark content, P c s (4338) and P c s (4459) ; its analysis points towards having both hadrons' isospins equal to zero and spin-parity quantum numbers 1 2 − and 3 2 − , respectively. Herein, we perform a systematical investigation of the q q s c c ¯ (q = u , d) system by means of a chiral quark model, along with a highly accurate computational method, the Gaussian expansion approach combined with the complex scaling technique. baryon-meson configurations in both singlet- and hidden-color channels are considered. The P c s (4338) and P c s (4459) signals can be well identified as molecular bound states with dominant components Λ J / ψ (60 %) and Ξ c D (23 %) for the lowest-energy case and Ξ c D ∗ (72 %) for the highest-energy one. In addition, it seems that some narrow resonances can also be found in each allowed I (J P) channel in the energy region of 4.6 – 5.5 GeV, except for the 1 (1 2 −) channel where a shallow bound state with dominant Ξ c ∗ D ∗ structure is obtained at 4673 MeV with binding energy E B = − 3 MeV. These exotic states are expected to be confirmed in future high-energy experiments. [ABSTRACT FROM AUTHOR]

Understanding the production mechanism of exotic hadrons with the structures beyond naive parton model can be helpful to find out their inner configuration and also to check the theory of quantum chromodynamics (QCD). Theoretically, fragmentation is known as the dominant production mechanism of conventional heavy hadrons with large transverse momentum so as this mechanism can also be considered for heavy pentaquarks production. In the present work, we first study the fragmentation function of S-wave fully heavy pentaquarks in leading-order perturbative QCD and then we will estimate their production cross section in pair annihilation process at lowest order of perturbation theory, relevant for the present and future high energy electron–positron colliders. [ABSTRACT FROM AUTHOR]

Hexaquarks are one of the currently emerging topics in both experimental and theoretical high energy physics. Hexaquarks have been examined in relation to particle physics, however, there are still some research and theoretical conjectures surrounding their relationship to dark matter. Due to some experimental discoveries, it has attracted much interest and also resulted in new theoretical models to study the properties of these states. In this work, Regge trajectories of some hexaquark states are compared with tetraquark and pentaquark states. The study is mainly concentrated on fully heavy hexaquark states. The mass spectra of these hexaquark states have also been investigated and the results are compared with other theoretical works. Our findings agree well with those of other researchers. [ABSTRACT FROM AUTHOR]

In this study, we investigate how the baryonic effects vary with scale and local density environment mainly by utilizing a novel statistic, the environment-dependent wavelet power spectrum (env-WPS). With four state-of-the-art cosmological simulation suites, EAGLE (Evolution and Assembly of GaLaxies and their Environments), SIMBA, Illustris, and IllustrisTNG, we compare the env-WPS of the total matter density field between the hydrodynamic and dark matter-only runs at z = 0. We find that the clustering is most strongly suppressed in the emptiest environment of |$\rho _\mathrm{m}/\bar{\rho }_\mathrm{m} \ \lt \ 0.1$| with maximum amplitudes ∼67–89 per cent on scales ∼1.86–10.96  h Mpc−1, and less suppressed in higher density environments on small scales (except Illustris). In the environments of |$\rho _\mathrm{m}/\bar{\rho }_\mathrm{m}\geqslant 0.316$| (≥10 in EAGLE), the feedbacks also lead to enhancement features at intermediate and large scales, which is most pronounced in the densest environment of |$\rho _\mathrm{m}/\bar{\rho }_\mathrm{m}\geqslant 100$| and reaches a maximum ∼7–15 per cent on scales ∼0.87–2.62  h Mpc−1 (except Illustris). The baryon fraction of the local environment decreases with increasing density, denoting the feedback strength, and potentially explaining some differences between simulations. We also measure the volume and mass fractions of local environments, which are affected by ≳1 per cent due to baryon physics. In conclusion, our results show that the baryonic processes can strongly modify the overall cosmic structure on the scales of k > 0.1  h Mpc−1, which encourages further research in this direction. [ABSTRACT FROM AUTHOR]

In this work, we analyse the density profiles of subhaloes with masses M sh ≥ 1.4 × 108 M⊙ in the TNG50 simulation, with the aim of including baryonic effects. We evaluate the performance of frequently used models, such as the standard Navarro–Frenk–White (NFW), the Einasto, and a smoothly truncated version of the NFW profile. We find that these models do not perform well for the majority of subhaloes, with the NFW profile giving the worst fit in most cases. This is primarily due to mismatches in the inner and outer logarithmic slopes, which are significantly steeper for a large number of subhaloes in the presence of baryons. To address this issue, we propose new three-parameter models and show that they significantly improve the goodness of fit independently of the subhalo's specific properties. Our best-performing model is a modified version of the NFW profile with an inner log-slope of −2 and a variable truncation that is sharper and steeper than the slope transition in the standard NFW profile. Additionally, we investigate how both the parameter values of the best density profile model and the average density profiles vary with subhalo mass, V max, distance from the host halo centre, baryon content, and infall time, and we also present explicit scaling relations for the mean parameters of the individual profiles. The newly proposed fit and the scaling relations are useful to predict the properties of realistic subhaloes in the mass range 108 M⊙ ≤ M sh ≤ 1013 M⊙ that can be influenced by the presence of baryons. [ABSTRACT FROM AUTHOR]

We study the possibly-existing molecular pentaquark states with open charm and bottom flavors, i.e., the states with the quark contents c b ¯ q q q and b c ¯ q q q ( q = u , d , s ). We investigate the meson-baryon interactions through the coupled-channel unitary approach within the local hidden-gauge formalism, and extract the poles by solving the Bethe-Salpeter equation in coupled channels. These poles qualify as molecular pentaquark states, which are dynamically generated from the meson-baryon interactions through the exchange of vector mesons. Our results suggest the existence of the Σ c (∗) B (∗) and Σ b (∗) D ¯ (∗) molecular states with isospin I = 1 / 2 , the Ξ c (′ , ∗) B (∗) and Ξ b (′ , ∗) D ¯ (∗) molecular states with isospin I = 0 and I = 1 , as well as the Ω c (∗) B (∗) and Ω b (∗) D ¯ (∗) molecular states with isospin I = 1 / 2 . [ABSTRACT FROM AUTHOR]

We have studied the strong decay properties of the recently observed T c s ¯ 0 a (2900) + + / 0 by considering it as a c u d ¯ s ¯ / c d u ¯ s ¯ fully open-flavor tetraquark state with I (J P) = 1 (0 +) . In the framework of QCD sum rules, we have calculated the three-point correlation functions of the two-body strong decay processes T c s ¯ 0 a (2900) + + → D s + π + , D + K + , D s ∗ + ρ + and D s 1 + π + . The full width of T c s ¯ 0 a (2900) + + / 0 is obtained as 161.7 ± 94.8 MeV, which is consistent with the experimental observation. We predict the relative branching ratios as Γ (T → D s π) : Γ (T → D K) : Γ (T → D s ∗ ρ) : Γ (T → D s 1 π) ≈ 1.00 : 1.10 : 0.04 : 0.43 , implying that the main decay modes of T c s ¯ 0 a (2900) + + / 0 state are D s π and DK channels in our calculations. However, the P-wave decay mode D s 1 π is also comparable and important by including the uncertainties. To further identify the nature of T c s ¯ 0 a (2900) + + / 0 , we suggest confirming them in the DK and D s π final states, and measuring the above ratios in future experiments. [ABSTRACT FROM AUTHOR]

‎In this paper‎, ‎we present an exact analytical solution for five interacting quarks‎. ‎We solve the Schr\"{o}dinger equation for pentaquarks in the framework of five-body and two-body problems‎. ‎For this purpose‎, ‎we utilize Yukawa potential in Jacobi coordinates‎. ‎Also finding the relation between the reduced masses and coupling constants of pentaquarks‎, ‎we obtain the coupling constant of Yukawa potential for pentaquark systems‎. ‎We calculate the energy of these systems in their ground state‎. ‎The results are well consistent with the theoretical results‎. ‎Our procedure to obtain these results is appropriate for other potentials and $n$-body systems‎.

In this paper, we analyze the properties of heavy quarkonia in a curved space-time with conical geometry induced by a topological defect, namely a cosmic string. The particles moving within the latter space are under the influence of an extended version of the Cornell potential. Assuming that the cosmic string space time is torsion free, the full spectrum of each particle is obtained by solving the Schrödinger equation using the extended Nikiforov–Uvarov method. It is observed that the gravitational field of the topological defect acts on the energy levels in a manner similar to the Zeeman effect due to the magnetic field. However, in the limit of the flat Minkowski space-time (α → 1) , we recover the classical mass spectra of heavy quarkonia for the extended Cornell potential. The numerical outcomes of this study are overall found in good agreement with experimental data and other relevant theoretical works. Thus, to illustrate the effect of the topological defect graphically, mass spectra, wave functions and radial probability densities are plotted for P - states at different values of α . It is found that, at large values of the quantum number n, the mass spectra of heavy quarkonia exhibit saturation effect governed by the topological parameter. [ABSTRACT FROM AUTHOR]

We derive and explicitly display the internal wave function of a color-, flavor- and spin- singlet dibaryon composed of uuddss quarks in a spatially symmetric state, in the approximation of exact SU(3) flavor symmetry. This wavefunction shows that the often-used superposition of ΛΛ, NΞ and ΣΣ baryons, relevant for di-baryon molecules, accounts for only 1/5 of a spatially symmetric six-quark color-flavor-spin-singlet state, with the remaining 4/5 consisting of products of color-octet baryons. Using the correct wavefunction has important implications for calculations of the mass of the lowest-lying flavor-singlet dibaryon, as we illustrate using the Cornell potential. We also provide a compact representation of the state in terms of creation operators, and comment on the impact of not using the optimal operator in lattice studies of this system. [ABSTRACT FROM AUTHOR]

The measurements on a few pentaquarks states P c (4440) , P c (4457) and P cs (4459) excite our new interests about their structures. Since the masses of P c (4440) and P c (4457) are close to the threshold of Σ c D ¯ ∗ , in the earlier works, they were regarded as molecular states of Σ c D ¯ ∗ with quantum numbers I (J P) = 1 2 (1 2 -) and 1 2 (3 2 -) , respectively. In a similar way P cs (4459) is naturally considered as a Ξ c D ¯ ∗ bound state with I = 0 . Within the Bethe-Salpeter (B-S) framework we systematically study the possible bound states of Λ c D ¯ ∗ , Σ c D ¯ ∗ , Ξ c D ¯ ∗ and Ξ c ′ D ¯ ∗ . Our results indicate that Σ c D ¯ ∗ can form a bound state with I (J P) = 1 2 (1 2 -) , which corresponds to P c (4440) . However for the I (J P) = 1 2 (3 2 -) system the attraction between Σ c and D ¯ ∗ is too weak to constitute a molecule, so P c (4457) may not be a bound state of Σ c D ¯ ∗ with I (J P) = 1 2 (3 2 -) . As Ξ c D ¯ ∗ and Ξ c ′ D ¯ ∗ systems we take into account of the mixing between Ξ c and Ξ c ′ and the eigenstets should include two normal bound states Ξ c D ¯ ∗ and Ξ c ′ D ¯ ∗ with I (J P) = 1 2 (1 2 -) and a loosely bound state Ξ c D ¯ ∗ with I (J P) = 1 2 (3 2 -) . The conclusion that two Ξ c D ¯ ∗ bound states exist, supports the suggestion that the observed peak of P cs (4459) may hide two states P cs (4455) and P cs (4468) . Based on the computations we predict a bound state Ξ c ′ D ¯ ∗ with I (J P) = 1 2 (1 2 -) but not that with I (J P) = 1 2 (3 2 -) . Further more accurate experiments will test our approach and results. [ABSTRACT FROM AUTHOR]

We study the masses and production modes of pentaquark with the quark constituent c q ¯ q q q , by the tridiquark-diquark model and systematical light flavor quark symmetry SU(3) analysis. The mass spectrums show that the S-wave singly charm pentaquark c n ¯ n n n , c s ¯ s s n , c n ¯ s s n and c n ¯ s n n (n = u , d) are above their strong decay thresholds, while c s ¯ n n n and c s ¯ s n n with parity 1 2 - are below their strong decay thresholds, which imply the possibility of stable states. Furthermore, we discuss the production of the concerned 15 states from B meson, the analysis within SU(3) symmetry yields the golden channels of production process, B ¯ s 0 → F s ¯ u d d + p ¯ , B - → F u ¯ d d s - Λ ¯ 0 , which expected to be work worthily in b-factory. [ABSTRACT FROM AUTHOR]

At present, production, properties, and decays of heavy baryons are vigorously studied both experimentally and theoretically. The flavor symmetry allows an existence of a large number of hidden charm pentaquark states which differ by their light quark content. Here, ratios of weak decay widths of bottom baryons into a pentaquark and light meson are presented. The most interesting for experimental observation decays of bottom baryons are specified. [ABSTRACT FROM AUTHOR]

Nuclear dynamics in the first six vibronically coupled electronic states of pentafluorobenzene radical cation is studied with the aid of the standard vibronic coupling theory and quantum dynamical methods. A model 6 × 6 vibronic Hamiltonian is constructed in a diabatic electronic basis using symmetry selection rules and a Taylor expansion of the elements of the electronic Hamiltonian in terms of the normal coordinate of vibrational modes. Extensive ab initio quantum chemistry calculations are carried out for the adiabatic electronic energies to establish the diabatic potential energy surfaces and their coupling surfaces. Both time-independent and time-dependent quantum mechanical methods are employed to perform nuclear dynamics calculations. The vibronic spectrum of the electronic states is calculated, assigned, and compared with the available experimental results. Internal conversion dynamics of electronic states is examined to assess the impact of various couplings on the nuclear dynamics. The impact of increasing fluorination of the parent benzene radical cation on its radiative emission is examined and discussed. [ABSTRACT FROM AUTHOR]

We generalize to five distinct flavors the flavor-spin hyperfine interaction introduced previously for four flavors and used in the study of u u d c c ¯ pentaquark. As a particular case here we study the lowest states of the pentaquark u u d b b ¯ , of either positive or negative parity, in a constituent quark model with linear confinement and the presently extended hyperfine interaction. The positive parity states have one unit of angular momentum located in the subsystem of four quarks and are described by translationally invariant states of orbital permutation symmetry [ 31 ] O which requires the configuration s 3 p . The negative parity states are described by the configuration s 4 of permutation symmetry [ 4 ] O . We show that the lowest state has the quantum numbers J P = 1 / 2 + or 3 / 2 + and I = 1/2 and is located below the Σ b B threshold by - 132 MeV. We present a comparison between the spectra of u u d c c ¯ and u u d b b ¯ pentaquarks. [ABSTRACT FROM AUTHOR]

The Dirac equation (DE) plays an essential role in the relativistic quantum systems, which is reduced to a form similar to Schrödinger equation when a certain potential's type is selected as the Cornell potential. By choosing the generalized fractional derivative, the fractional Nikiforov–Uvarov method is applied as a good efficient tool. The energy eigenvalues and corresponding wave functions are obtained in the sense of fractional forms by solving DE analytically. The special case is obtained, which is compatible with the classical model. In addition, we applied the present results on the light mesons such as D , D s and B s. Solving the fractional DE will open a new path to solve and improve results in the classical relativistic quantum systems. [ABSTRACT FROM AUTHOR]

In this work, we systematically investigate the singly charmed pentaquark molecular states D (∗) N ,  D (∗) Ξ (∗) and D s (∗) Ξ (∗) with the QCD sum rules by carrying out the operator product expansion up to the vacuum condensates of dimension 13 and taking fully account of the light-flavor S U (3) breaking effects. The numerical results favor assigning the Ω c (3 1 8 5) as the D Ξ molecular state with the J P = 1 2 − and | I , I 3 〉 = | 0 , 0 〉 , assigning the Ω c (3 3 2 7) as the D ∗ Ξ molecular state with the J P = 3 2 − and | I , I 3 〉 = | 0 , 0 〉 , assigning the Σ c (2 8 0 0) as the D N molecular state with the J P = 1 2 − and | I , I 3 〉 = | 1 , 0 〉 , and assigning the Λ c (2 9 4 0) / Λ c (2 9 1 0) as the D ∗ N molecular state with the J P = 3 2 − and | I , I 3 〉 = | 0 , 0 〉. Other potential molecule candidates are also predicted, which may be observed in future experiments. For example, we can search for the D Ξ and D ∗ Ξ molecular states with the isospin | I , I 3 〉 = | 1 , ± 1 〉 in the Ξ c + K ̄ 0 and Ξ c 0 K ̄ − mass spectrum, respectively, in the future, which could shed light on the nature of the Ω c (3 1 8 5 / 3 3 2 7). [ABSTRACT FROM AUTHOR]

According to the classification of the quark model, the hadrons going beyond three-quark baryon and quark-antiquark meson pictures are called exotic hadrons. Many new hadrons have been observed since 2003, some of which exhibit exotic behaviors. There are a lot of excellent review articles on exotic hadrons available so far; the present article tries to focus on the recent experimental and theoretical progress on the exotic states from the perspective of the quark model. Although lattice quantum chromodynamics may give the final answer of the problem, the phenomenological models are still powerful tools to explore the exotic states and to provide insight on the phenomenology of hadrons. The spatial and color structures of multiquark states and the channel coupling calculation are emphasized through reviewing some bound states, molecular and color structure resonances. Finally, the unquench effects of some exotic states are reviewed. With the accumulation of experimental data on multiquark states and inspiration of underlying theory developments, more reasonable phenomenological models incorporating multi-body interactions and high Fock components to unify the description of normal hadrons and exotic hadrons are expectable. [ABSTRACT FROM AUTHOR]

Inspired by the fully heavy tetraquark states reported by the LHCb, ATLAS and CMS Collaborations, we perform a systematical investigation of the low-lying fully heavy pentaquark systems composed of charm and bottom quarks (anti-quark) in the chiral quark model. With the help of the channel-coupling, we obtain several fully heavy pentaquark candidates, which are c c c c b ¯ and b b b b c ¯ systems with J P = 1 / 2 - and 3 / 2 - , c c c b c ¯ , b b b c b ¯ , c c c b b ¯ and b b b c c ¯ systems with J P = 5 / 2 - . The binding energies of these states are all below 10 MeV and the root mean square (RMS) are around 1.8 fm, which indicates that these states are likely to be molecular states. These predicted exotic states may provide new ideas for experimental searches and we expect more experimental and theoretical researches to study and understand the fully heavy states in future. [ABSTRACT FROM AUTHOR]

Motivated by recent progresses in experiments in searching for the Ω c baryons, we systematically analyze the strong decay behaviors of single heavy baryons Λ Q , Σ Q and Ω Q . The two-body strong decay properties of S -wave, P -wave and some D -wave states are studied with the 3 P 0 model. The results support assigning the recently observed Ω c (3 1 8 5) and Ω c (3 3 2 7) as the 2S( 3 2 + ) and 1D( 3 2 + ) states, respectively. In addition, the quantum numbers of many other experimentally observed baryons are also suggested according to their strong decays. Finally, some baryons which have good potentials to be observed in experiments are predicted and the possible decay channels for searching for these predicted states are also suggested. [ABSTRACT FROM AUTHOR]

Inspired by the LHCb observation of hidden-charm pentaquarks, i.e., P c (4312) , P c (4440) , and P c (4457) in the J / ψ p invariant mass spectrum, a calculation of the J / ψ p scattering cross-section was performed using the quark-delocalization color screening model. The results show that P c (4312) can be identified as a hidden-charm molecular state Σ c D with J P = 1 2 − . The two-peak structure can be reproduced around 4450 MeV, which corresponds to P c (4440) and P c (4457) . They are the resonances molecular states Σ c D * of J P = 1 2 − and J P = 3 2 − . Moreover, the Σ c * D * of both J P = 1 2 − and J P = 3 2 − are possible molecular pentaquarks. Moreover, in the same theoretical frame, the calculation is extended to the P c -like molecular pentaquarks, denoted as P b . Several hidden-bottom pentaquarks with masses above 11 GeV and narrow widths were obtained. All of these heavy pentaquarks are worth exploring in future experiments. [ABSTRACT FROM AUTHOR]

Motivated by the recent observation of the Λ c (2910) + state in the Σ c (2455) 0 , + + π ± spectrum by the Belle Collaboration, we investigate the explanation of Λ c states within the pentaquark framework using the quark delocalization color screening model (QDCSM). To check for bound states and resonance states, we utilize the real-scaling method. Additionally, we calculate the root mean square of cluster spacing to study the structure of the states and further estimate whether a state is a resonance state or not. Our numerical results show that Λ c (2910) cannot be interpreted as a molecular state, and Σ c (2800) cannot be explained as the ND molecular state with J P = 1 / 2 - . However, we find that Λ c (2595) can be interpreted as a molecular state with J P = 1 2 - , where the main component is Σ c π . Similarly, we interpret Λ c (2625) as a molecular state with J P = 3 2 - , where the main component is Σ c ∗ π . We also suggest that Λ c (2940) is likely to be interpreted as a molecular state with J P = 3 / 2 - , where the main component is N D ∗ . In addition, we predict two new states: a J P = 3 / 2 - Σ c ρ resonance state with a mass of 3140–3142 MeV, and a J P = 5 2 - Σ c ∗ ρ state with a mass about 3187–3188 MeV. [ABSTRACT FROM AUTHOR]

We describe the implementation of infrared subtractions for two-loop QCD corrections to quark-antiquark annihilation to electroweak final states. The subtractions are given as form-factor integrands whose integrals are known. The resulting subtracted amplitudes are amenable to efficient numerical integration. Our procedure is based on the universality of infrared singularities and requires a relatively limited set of subtractions, whose number grows as the number of two-loop diagrams, rather than with the number of singular regions of integration. [ABSTRACT FROM AUTHOR]

We study compact hidden charm pentaquarks in the Born–Oppenheimer approximation, previously introduced for tetraquarks, assuming the heavy pair to be in a color octet. We show that Fermi statistics applied to the complex of the three light quarks, also in color octet, requires S-wave pentaquark ground states to consist of three octets of flavour-SU(3) f , two with spin 1/2 and one with spin 3/2, in line with the observed, strangeness S = 0 , - 1 , spectrum. Additional lines corresponding to decays into J / ψ + Σ and J / ψ + Ξ are predicted. In the language of non-relativistic SU(6), ground state pentaquarks form either a 56 or a 20 representation, distinguished by presence or absence of pentaquarks decaying in the spin 3/2 decuplet, e.g. in J / ψ + Δ + + . Observation of a strangeness S = - 2 or isospin I = 3 / 2 pentaquarks would be a clear signature of compact, QCD bound pentaquarks. [ABSTRACT FROM AUTHOR]

Inspired by recent progresses in observations of the fully charmed tetraquark states by LHCb, CMS, and ATLAS collaborations, we perform a systematic study of the ground states and the first radial excitations of the S- and P-wave cc c ¯ c ¯ system. Their mass spectra, root mean square (r.m.s.) radii and radial density distributions are studied with the relativized quark model. The calculations show that there is no stable bound states for the fully charmed tetraquark states, and the r.m.s. radii of these tetraquark states are smaller than 1 fm. Our results support assigning X(6600) structure, M X (6600) = 6552 ± 10 ± 12 MeV, as one of the 0 + + (1S) and 2 + + (1S) states or their mixtures. Another structure also named as X(6600) by CMS Collaboration, M X (6600) = 6.62 ± 0. 03 - 0.01 + 0.02 GeV, may arise from the lowest 1P states with J PC = 0 - + , 1 - + , and 2 - + . The possible assignments for X(6900) include the 0 + + (2S), 2 + + (2S) states, and the highest 1P state with J PC = 0 - + . As for X(7200), it can be interpreted as one of the highest 2P states with J PC = 0 - + , 1 - + , and 2 - + , and the 3S states can not be completely excluded from the candidates. [ABSTRACT FROM AUTHOR]

We investigate whether the soft mode that becomes massless at the QCD critical point (CP) causes an enhancement of the dilepton production rate (DPR) and electric conductivity around the CP through modification of the photon self-energy using the two-flavor Nambu–Jona-Lasinio model. The modification is described by the so-called Aslamazov–Larkin, Maki–Thompson, and density of states terms, which have been taken into account in our previous study on the DPR near the color-superconducting phase transition, with a replacement of the diquark modes with the soft mode of the QCD CP. We show that the coupling of photons with the soft modes brings about an enhancement of the DPR in the low-invariant-mass region and the conductivity near the CP, which would be observable in relativistic heavy-ion collisions. [ABSTRACT FROM AUTHOR]

In recent years, many tetraquarks and pentaquarks have been discovered by various experimental groups and X (3 8 7 2) , Z c (3 9 0 0) , X (4 4 3 0) , P c + (4 3 1 2) , P c + (4 4 5 7) are some of the interesting observed tetraquark and pentaquark states. The Regge trajectories of some such states are studied in view of the flux tube model of hadrons with finite quark masses. The effect of flux tube (or string) length variation on the Regge trajectories of these states is analyzed in detail. It is observed that for a fixed angular momentum, the string length has a constant value. Some other states are also proposed and the results obtained are then compared with the studies by others. Our findings correspond rather well with those of other researchers and with those of the experiment. [ABSTRACT FROM AUTHOR]

The mass-spectra of all-charm tetraquark states [ c c ] [ c ¯ c ¯ ] with the diquark-antidiquark configuration are investigated in this study. To determine the fitting parameters for the calculation of masses of all-charm tetraquarks states [ c c ] [ c ¯ c ¯ ], we first calculate the mass-spectra of charmonia [ c c ¯ ] and its decay constants ( f P / V 2 ). We estimated the masses of the tetraquark states in their ground state along with their radially and orbitally excited states. The spin-spin, spin-orbital, and tensor interactions are perturbatively added to the central potential to produce the mass-spectra of tetraquark states. The charmonia findings obtained in this study are reasonably consistent with earlier experimental and theoretical expectations, whereas the masses of the tetraquark states are in accordance with prior theoretical predictions. The mass discrepancy in the present study are having nearly 100 MeV for 3S-wave ( 0 + + and 2 + + ) and nearly 50 MeV for 2P-wave ( 0 - + , 1 - + and 2 - + ) states from experimental data. We propose that the X(6900) state, which has all charm [ c c ] [ c ¯ c ¯ ] in its constituent and was recently detected by LHCb, could be classified as either radially (3S-wave) or orbitally (2P-wave) excited states. [ABSTRACT FROM AUTHOR]

Layered nanomaterials with in‐plane anisotropy exhibit unique orientation‐dependent responses to external stimuli, enabling the development of novel devices with additional degrees of freedom. In particular, their anisotropic optical properties enable ultrafast nanophotonic modulators to be controlled by light polarization. However, achieving high controllability is still challenging due to incomplete optical anisotropy in most materials. Here, this work presents a completely anisotropic, ultrafast optical modulation in zirconium pentatelluride (ZrTe5), a layered nanomaterial that has recently attracted renewed attention. The transient absorption (TA) microscopy reveals anisotropic ultrafast picosecond optical modulation in a broad range of 1.2–2.2 eV. In particular, at a certain photon‐energy of 1.62 eV, complete on/off switching with a near‐unity degree of anisotropy is achieved solely by changing the light polarization, suggesting that ZrTe5 is a promising material for polarization‐selective high‐speed optical modulators. The theoretical analysis of the transition dipole moments attributes this sharp anisotropy to strongly polarization‐dependent excited‐state absorption. Furthermore, this work directly observes direction‐dependent photocarrier transport using scanning TA microscopy. It yields the anisotropic diffusivity, mobility, and diffusion lengths of the photocarriers, which are essential parameters for designing devices. Therefore, this work provides a comprehensive understanding of the anisotropic optical characteristics of ZrTe5 on ultrafast timescales. [ABSTRACT FROM AUTHOR]

Layered nanomaterials with in‐plane anisotropy exhibit unique orientation‐dependent responses to external stimuli, enabling the development of novel devices with additional degrees of freedom. In particular, their anisotropic optical properties enable ultrafast nanophotonic modulators to be controlled by light polarization. However, achieving high controllability is still challenging due to incomplete optical anisotropy in most materials. Here, this work presents a completely anisotropic, ultrafast optical modulation in zirconium pentatelluride (ZrTe5), a layered nanomaterial that has recently attracted renewed attention. The transient absorption (TA) microscopy reveals anisotropic ultrafast picosecond optical modulation in a broad range of 1.2–2.2 eV. In particular, at a certain photon‐energy of 1.62 eV, complete on/off switching with a near‐unity degree of anisotropy is achieved solely by changing the light polarization, suggesting that ZrTe5 is a promising material for polarization‐selective high‐speed optical modulators. The theoretical analysis of the transition dipole moments attributes this sharp anisotropy to strongly polarization‐dependent excited‐state absorption. Furthermore, this work directly observes direction‐dependent photocarrier transport using scanning TA microscopy. It yields the anisotropic diffusivity, mobility, and diffusion lengths of the photocarriers, which are essential parameters for designing devices. Therefore, this work provides a comprehensive understanding of the anisotropic optical characteristics of ZrTe5 on ultrafast timescales. [ABSTRACT FROM AUTHOR]

In the present work, we construct the diquark-antidiquark type four-quark currents to investigate the mass spectrum of the ground state hidden-charm-hidden-strange tetraquark states with the quantum numbers J P C = 0 + + , 1 + − , 1 + + and 2 + + via the traditional QCD sum rules in a comprehensive way. We update old calculations, perform new calculations and analysis in a rigorous way, and take account of the net light-flavor S U (3) breaking effects in a consistent way. And we make more reasonable identifications for the X (3960) , X (4140) , X (4274) , X (4500) , X (4685) and X (4700) and supersede some old identifications. Furthermore, we consider our previous theoretical predictions, and make reasonable/suitable identifications of the new LHCb states h c (4000) and χ c 1 (4010). [ABSTRACT FROM AUTHOR]

In the paper, we study the production of pentaquark c ¯ q q q q from singly bottom baryon. The tensor representations of pentaquark c ¯ q q q q are completed at first. Under the light quark symmetry analysis, we decompose the singly charmed pentaquarks into 6, 15 and 15 ′ multiple states, and deduce the representations of these states. Then we construct the production Hamiltonian of the multiple states in proper order. For completeness, we systematically study the production channels of pentaquark states, including the possible production amplitudes and decay relations between different channels, concurrently, the widths of selected channels are worked out with the effective Lagrangian approach. Ultimately, we expect that the chosen channels will be fairly valuable supports for future search experiments. [ABSTRACT FROM AUTHOR]

Fluctuating light (FL) can cause the selective photoinhibition of photosystem I (PSI) in angiosperms. In nature, leaves usually experience FL conditions with the same low light and different high light intensities, but the effects of different FL conditions on PSI redox state and PSI photoinhibition are not well known. In this study, we found that PSI was highly reduced within the first 10 s after transition from 59 to 1809 μmol photons m−2 s−1 in tomato (Solanum lycopersicum). However, such transient PSI over-reduction was not observed by transitioning from 59 to 501 or 923 μmol photons m−2 s−1. Consequently, FL (59-1809) induced a significantly stronger PSI photoinhibition than FL (59-501) and FL (59-923). Compared with the proton gradient (∆pH) level after transition to high light for 60 s, tomato leaves almost formed a sufficient ∆pH after light transition for 10 s in FL (59-501) but did not in FL (59-923) or FL (59-1809). The difference in ∆pH between 10 s and 60 s was tightly correlated to the extent of PSI over-reduction and PSI photoinhibition induced by FL. Furthermore, the difference in PSI photoinhibition between (59-923) and FL (59-1809) was accompanied by the same level of linear electron flow. Therefore, PSI photoinhibition induced by different intensities of FL is more related to the kinetics of ∆pH formation rather than linear electron flow. [ABSTRACT FROM AUTHOR]

In the paper, we construct eight color singlet–singlet-type five-quark currents with distinguished isospins to study the D ̄ Ξ ′ , D ̄ Ξ c ∗ , D ̄ ∗ Ξ c ′ and D ̄ ∗ Ξ c ∗ molecular states with strangeness via the QCD sum rules. Numerical results show that the central values of the pentaquark masses with higher (lower) isospin are slightly above (below) the thresholds of the corresponding meson–baryon pairs, and support assigning the P c s (4 4 5 9) as the D ̄ Ξ c ∗ molecular state with the quantum numbers I J P = 0 3 2 − . The other predictions can be confronted to the experimental data in the future. [ABSTRACT FROM AUTHOR]

In this paper, we construct the diquark–diquark–diquark-type vector six-quark currents to investigate the vector and scalar hexaquark states in the framework of the QCD sum rules in a consistent way, and make predictions for the hexaquark masses. We can search for the fully heavy hexaquark states in the di- Ω c c c and di- Ω b b b invariant mass spectra in the future. Combined with our previous works on the fully heavy tetraquark states and pentaquark states, the present predictions can shed light on the nature of the fully heavy multiquark states. [ABSTRACT FROM AUTHOR]

We compute the modification of the photon self-energy due to dynamical diquark fluctuations developed near the critical temperature of two-flavor superconductivity, which is one of the color superconducting phases, through the Aslamasov–Larkin, Maki–Thompson, and density of states terms, which are responsible for the paraconductivity in metals at vanishing energy and momentum. The analysis is performed through an investigation of the diquark fluctuations within the normal phase determined by the mean-field approximation in the massless two-flavor Nambu–Jona-Lasinio model. It is shown that the rate has a significant enhancement in low-invariant-mass regions over a rather wide range of temperatures in the normal phase. This enhancement is worth exploring in the relativistic heavy-ion collisions, which may thereby reveal the significance of the diquark fluctuations in dense quark matter. [ABSTRACT FROM AUTHOR]

We perform a theoretical study on the D D ¯ K three body system, using the fixed center approximation to the Faddeev equations, considering the interaction between D and K, D and D ¯ from the chiral unitary approach. We assume the scattering of K meson on a clusterized system D D ¯ , where a scalar meson X(3720) could be formed. Thanks to the strong DK interaction, where the scalar D s 0 ∗ (2317) meson is dynamically generated, a resonance structure shows up in the modulus squared of the three body K- (D D ¯) X (3720) scattering amplitude and supports that a D D ¯ K bound state can be formed. The result is in agreement with previous theoretical studies, which claim a new excited hidden charm K meson, K c c ¯ (4180) with quantum numbers I (J P) = 1 2 (0 -) and mass about 4180 MeV. It is expected that these theoretical results motivate its search in experimental measurements. [ABSTRACT FROM AUTHOR]

Spectrum of the low-lying hidden- and double-charm tetraquark states are investigated in a nonrelativistic quark potential model, where the instanton-induced interaction is taken as the residual spin-dependent hyperfine interaction between quarks. The model parameters are fixed by fitting the spectrum of the ground hadron states. Our numerical results show that masses of several presently studied tetraquark states are close to those of the experimentally observed candidates of exotic meson, which indicates that the corresponding compact tetraquark components may take considerable probabilities in those observed exotic states. [ABSTRACT FROM AUTHOR]

We consider a QCD cold-plasma-motivated Equation of State (EOS) to examine the impact of an Anomalous Magnetic Moment (AMM) coupling and small shape deformations on the static oblate and prolate core shapes of quark stars. Using the Fogaça QCD-motivated EOS, which shifts from the high-temperature, low-chemical-potential quark–gluon plasma environment to the low-temperature, high-chemical-potential quark stellar core environment, we consider the impact of an AMM coupling with a metric-induced shape deformation parameter in the Tolman–Oppenheimer–Volkov (TOV) equations. The AMM coupling includes a phenomenological scaling that accounts for the weak and strong field characteristics in dense matter. The EOS is developed using a hard gluon and soft gluon decomposition of the gluon field tensor and using a mean-field effective mass for the gluons. The AMM is considered using the Dirac spin tensor coupled to the EM field tensor with quark-flavor-based magnetic moments. The shape parameter is introduced in a metric ansatz that represents oblate and prolate static stellar cores for modified TOV equations. These equations are numerically solved for the final mass and radius states, representing the core collapse of a massive star with a phase transition leading to an unbound quark–gluon plasma. We find that the combined shape parameter and AMM effects can alter the coupled EOS–TOV equations, resulting in an increase in the final mass and a decrease in the final equatorial radius without collapsing the core into a black hole and without violating causality constraints; we find maximum mass values in the range 1.6 Mʘ < M < 2.5 Mʘ. These states are consistent with some astrophysical, high-mass magnetar/pulsar and gravity wave systems and may provide evidence for a core that has undergone a quark–gluon phase transition such as PSR 0943 + 10 and the secondary from the GW 190814 event. [ABSTRACT FROM AUTHOR]

According to the classification of the quark model, the hadrons going beyond three-quark baryon and quark-antiquark meson pictures are called exotic hadrons. Many new hadrons have been observed since 2003, some of which exhibit exotic behaviors. There are a lot of excellent review articles on exotic hadrons available so far; the present article tries to focus on the recent experimental and theoretical progress on the exotic states from the perspective of the quark model. Although lattice quantum chromodynamics may give the final answer of the problem, the phenomenological models are still powerful tools to explore the exotic states and to provide insight on the phenomenology of hadrons. The spatial and color structures of multiquark states and the channel coupling calculation are emphasized through reviewing some bound states, molecular and color structure resonances. Finally, the unquench effects of some exotic states are reviewed. With the accumulation of experimental data on multiquark states and inspiration of underlying theory developments, more reasonable phenomenological models incorporating multi-body interactions and high Fock components to unify the description of normal hadrons and exotic hadrons are expectable.

A reaction model for γ + p → J / ψ + p photoproduction, which exposes the c c ¯ content of the photon in making the transition γ → c c ¯ + P → J / ψ and couples the intermediate c c ¯ system to the proton's valence quarks via Pomeron (P) exchange, is used to deliver a description of available data, viz. both differential and total cross sections from near threshold, where data has newly been acquired, to invariant mass W ≈ 300 GeV. The study suggests that it is premature to link existing γ + p → J / ψ + p data with, for instance, in-proton gluon distributions, the quantum chromodynamics trace anomaly, or pentaquark production. Further developments in reaction theory and higher precision data are necessary before the validity of any such connections can be assessed. [ABSTRACT FROM AUTHOR]

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We consider the theory of spinor fields in polar form, where the spinorial true degrees of freedom are isolated from their Goldstone states, and we show that these carry information about the frames which is not related to gravitation, so that their propagation is not restricted to be either causal or local: we use them to build a model of entangled spins where a singlet possesses a uniform rotation that can be made to collapse for both states simultaneously regardless their spatial distance. Models of entangled polarizations with similar properties are also sketched. An analogy with the double-slit experiment is also presented. General comments on features of Goldstone states are given. [ABSTRACT FROM AUTHOR]

The interactions of D ¯ (∗) Λ c - D ¯ (∗) Σ c (∗) are studied within the framework of a dynamical coupled-channel approach. A series of bound states and resonances with different spin and parity are dynamically generated in the hidden charm sector. Four S-wave bound states are found in the mass range of 4.3–4.5 GeV, close to the pentaquark states observed by LHCb. Two of the states have a spin parity of J P = 1 / 2 - and the other two have J P = 3 / 2 - . In addition, several resonances with different spin and parity in higher partial waves are predicted. [ABSTRACT FROM AUTHOR]