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 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]

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]

We perform a systematic study of the electromagnetic properties of exotic states to shed light on their nature, which is still controversial and not fully understood. The magnetic dipole and higher multipole moments of a hadronic state are as fundamental a dynamical quantity as its mass, and they contain valuable information about the deep structure underlying it. In the present work, we have explored the magnetic dipole and higher multipole moments of the hidden-charm pentaquarks with quantum number J P = 3 / 2 − using the QCD light-cone sum rule method and different interpolating currents. The obtained results show that different interpolating currents employed to probe pentaquarks with the same quark content produce varying results for their magnetic dipole and higher multipole moments at all. This can be interpreted to mean that there is more than one hidden-charm pentaquark with identical quark content but with different magnetic dipole and higher multipole moments. The nature, internal structure, and quark-gluon configurations of these states can be better understood by studying their electromagnetic properties. [ABSTRACT FROM AUTHOR]

We study the near-threshold ϒ (1 S) meson photoproduction from protons and nuclei by considering incoherent direct non-resonant (γ p → ϒ (1 S) p , γ n → ϒ (1 S) n) and two-step resonant (γ p → P b i + → ϒ (1 S) p , γ n → P b i 0 → ϒ (1 S) n , i = 1 , 2, 3; P b 1 + , 0 = P b + , 0 (11080) , P b 2 + , 0 = P b + , 0 (11125) , P b 3 + , 0 = P b + , 0 (11130)) bottomonium production processes with the main goal of clarifying the possibility to observe the non-strange hidden-bottom pentaquark states P b i + , 0 in this production via differential observables. We calculate the absolute excitation functions, energy and momentum distributions for the non-resonant, resonant and for the combined (non-resonant plus resonant) production of ϒ (1 S) mesons on protons, on carbon and tungsten target nuclei at near-threshold incident photon beam energies by assuming the spin-parity assignments of the hypothetical hidden-bottom resonances P b + , 0 (11080) , P b + , 0 (11125) and P b + , 0 (11130) as J P = (1 / 2) − , J P = (1 / 2) − and J P = (3 / 2) − within four different realistic choices for the branching ratios of their decays to the ϒ (1 S) p and ϒ (1 S) n modes (0.125, 0.25, 0.5 and 1%) as well as for two options for the background contribution. We demonstrate that the measurements of these combined observables on proton and nuclear targets in the near-threshold energy region in future experiments at the planned high-luminosity electron-ion colliders EIC and EicC in the US and China should provide evidence for the existence of the above hidden-bottom pentaquark resonances as well as clarify their decay rates. [ABSTRACT FROM AUTHOR]

In this paper we study the magnetic dipole moments of the newly discovered Ω c (3185) 0 and Ω c (3327) 0 , assuming that Ω c (3185) 0 and Ω c (3327) 0 are S -wave D Ξ and D ⁎ Ξ molecular pentaquark states, respectively. Together with these states, the magnetic dipole moments of possible D s Ξ , D s ⁎ Ξ , D Ξ ⁎ , and D s Ξ ⁎ pentaquark states are also studied. The magnetic dipole moments of these singly-charmed pentaquarks are estimated within the framework of the QCD light cone sum rules utilizing the photon distribution amplitudes. In the search for the properties of singly-charmed molecular pentaquark states, the results obtained for the magnetic dipole moments can be useful. [ABSTRACT FROM AUTHOR]

Computations of screening masses in finite-temperature QCD at finite density are plagued by the sign problem and have been performed so far with an imaginary chemical potential. Here, we use a dual formulation of a Polyakov-loop model which allows the determination of screening masses at real baryon chemical potential. This is a second paper in a series devoted to a detailed study of dual Polyakov-loop models at finite density. While the first paper was mainly devoted to establishing the phase diagram of the model, here we compute correlation functions of the Polyakov loops and the second-moment correlation length at non-zero chemical potential. This enables us to evaluate numerically the screening masses from correlations of the real and imaginary parts of the Polyakov loops. We also compute these masses in the mean-field approximation and compare with numerical results. In addition, we provide a quantitative improvement of the general phase diagram presented in the first paper. [ABSTRACT FROM AUTHOR]