Molecule Picture Research Articles

Production of the X(4014) as the Spin-2 Partner of X(3872) in e + e − Collisions

In 2021, the Belle collaboration reported the first observation of a new structure in the ψ(2S)γ final state produced in the two-photon fusion process. In the hadronic molecule picture, this new structure can be associated with the shallow isoscalar D*D¯* bound state and as such is an excellent candidate for the spin-2 partner of the X(3872) with the quantum numbers J PC = 2++ conventionally named X 2. In this work we evaluate the electronic width of this new state and argue that its nature is sensitive to its total width, the experimental measurement currently available being unable to distinguish between different options. Our estimates demonstrate that the planned Super τ-Charm Facility offers a promising opportunity to search for and study this new state in the invariant mass distributions for the final states J/ψγ and ψ(2S)γ.

Anticharmed strange pentaquarks from the one-boson-exchange model

Inspired by the LHCb's discovery of hidden-charm pentaquarks, the anticharmed strange pentaquarks ${P}_{\overline{c}s}$ in a favor of the hadronic molecule picture are investigated from the one-boson-exchange model. Similar to the hidden-charm pentaquarks, three molecular bound states, one with spin parity ${J}^{P}=1/{2}^{\ensuremath{-}}$ below the $\overline{D}\mathrm{\ensuremath{\Sigma}}$ threshold and another two with ${J}^{P}={1/{2}^{\ensuremath{-}},3/{2}^{\ensuremath{-}}}$ below the ${\overline{D}}^{*}\mathrm{\ensuremath{\Sigma}}$ threshold, are predicted at 3--3.2 GeV mass region. The mass ordering of the later two states can be interchanged by different reductions of the $\ensuremath{\delta}(\mathbit{r})$ term. Furthermore, resonances associated with these three bound states are examined by considering ${D}_{s}^{\ensuremath{-}}N\ensuremath{-}\overline{D}\mathrm{\ensuremath{\Lambda}}\ensuremath{-}\overline{D}\mathrm{\ensuremath{\Sigma}}\ensuremath{-}{\overline{D}}^{*}\mathrm{\ensuremath{\Lambda}}\ensuremath{-}{\overline{D}}^{*}\mathrm{\ensuremath{\Sigma}}$ coupled-channel dynamics, and decay widths of them are predicted. Our study indicates that the ${D}_{s}^{\ensuremath{-}}p$ invariant mass spectrum in the ${\overline{B}}_{s}^{0}\ensuremath{\rightarrow}\overline{n}{D}_{s}^{\ensuremath{-}}p$ decay is an appropriate place to detect the ${P}_{\overline{c}s}$ pentaquarks.

Searching for strange hidden-charm pentaquark state Pcs(4459) in γp→K+Pcs(4459) reaction

We investigate the possibility of studying the strange hidden-charm pentaquark state $P_{cs}(4459)$ by photon-induced reactions on a proton target in an effective Lagrangian approach. The production process is described by the $t$-channel $K^{-}$ exchange, the $u$-channel $\Lambda$ exchange, the contract term, and the $s$- channel nucleon pole. Our theoretical approach is based on the assumption that $P_{cs}(4459)$ with $J^{P}=1/2^{-}$ or $J^{P}=3/2^{-}$ can be interpreted as a molecule composed of $\bar{D}^{*}\Xi_c$. Using the coupling constants of the $P^{J^P}_{cs}$ to $\gamma{}\Lambda$ and $K^{-}p$ channels obtained from molecule picture of the $P^{J^{P}}_{cs}(4459)$, the total cross-sections of the process $\gamma{}p\to{}P^{J^P}_{cs}K^{+}$ is evaluated. Our calculation indicates that the cross-section for $\gamma{}p\to{}P^{1/2^{-}}_{cs}K^{+}$ and $\gamma{}p\to{}P^{3/2^{-}}_{cs}K^{+}$ are of the order of 10.0 pb and 5.0 pb, respectively. In addition, we compute the cross-section by assuming $P_{cs}(4459)$ as a compact pentaquark and find it is quite different from the results of $\bar{D}^{*}\Xi_c$ molecule. Those results can be measured in future experiments, such as the Electron-Ion Collider in China and the United States. And can be used to test the nature of the $P_{cs}$.

Radiative decay of the Ξ(1620) in a hadronic molecule picture * *Supported by the Science and Technology Research Program of Chongqing Municipal Education Commission (KJQN201800510), the Opened Fund of the State Key Laboratory on Integrated Optoelectronics (IOSKL2017KF19). Yin Huang want to thanks the support from the Development and Exchange Platform for the Theoretic Physics of Southwest Jiaotong University (11947404, 12047576),

Last year, the state, which is cataloged in the Particle Data Group (PDG) with only one star, was reported again in the final state by the Belle Collaboration. Its properties, such as the spectroscopy and decay width, cannot be simply explained in the context of conventional constituent quark models. This inspires an active discussion on the structure of this resonance. In this paper, we study the radiative decays of the newly observed assuming that it is a meson-baryon molecular state of and with spin-parity developed in our previous study. The partial decay widths of the molecular state into and final states through hadronic loops are evaluated using effective Lagrangians. The partial widths for is evaluated to be approximately keV, which may be accessible for the LHCb experiment. If is a molecule, the radiative transition strength is considerably small and the decay width is of the order of 0.01 eV. Future experimental measurements of these processes can be useful to test the molecule interpretations of the .

Vibrational spectroscopy and phonon‐related properties of monoclinic GABA, a non‐proteinogenic inhibitory neurotransmitter amino acid

AbstractThe γ‐aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in vertebrate central nervous systems. Taking full account of the measured X‐ray diffractogram of its stable monoclinic polymorph, we have performed density functional theory (DFT) calculations to analyze/understand its infrared and Raman spectra considering its monoclinic polymorph, an isolated stabilized (120) plane, and a single GABA molecule. Besides, phonon dispersion/density of states, heat capacity, Debye temperature, and entropy/enthalpy/free energies were also obtained for the GABA monoclinic crystal. Vibrational signatures due to the GABA (120) planes are pointed out for the first time for several wavenumbers. The results obtained for the GABA monoclinic polymorph reinforce the need of dispersion‐corrected solid‐state calculations to describe the vibrational properties of molecular crystals instead of considering a single isolated molecule picture, even for wavenumbers larger than those usually associated with lattice modes.

Strong decays of the varXi (1620)^0 as a varLambda {bar{K}} and varSigma {bar{K}} molecule

In this work, we study the strong decays of the newly observed varXi (1620)^0 assuming that it is a meson-baryon molecular state of varLambda {bar{K}} and varSigma {bar{K}}. We consider four possible spin-parity assignments J^P=1/2^{pm } and 3/2^{pm } for the varXi (1620)^0, and evaluate its partial decay width into varXi pi and varXi pi pi via hadronic loops with the help of effective Lagrangians. In comparison with the Belle data, the calculated decay width favors the spin-party assignment 1/2^- while the other spin-parity assignments do not yield a decay width consistent with data in the molecule picture. We find that about 52–68% of the total width comes from the {bar{K}}varLambda channel, while the rest is provided by the {bar{K}}varSigma channel. As a result, both channels are important in explaining the strong decay of the varXi (1620)^0. In addition, the transition varXi (1620)^0rightarrow pi varXi is the main decay channel in the J^{P}=1/2^{-} case, which almost saturates the total width. These information are helpful to further understand the nature of the varXi (1620)^0.

Radiative decay of in a hadronic molecule picture * * This work is partly supported by the Development and Exchange Platform for Theoretic Physics of Southwest Jiaotong University in 2020 (11947404). We acknowledge the supported by the National Science Foundation of Chongqing (cstc2019jcyj-msxm0953), the Science and Technology Research Program of Chongqing Municipal Education Commission (KJQN201800510). This work is also supported

The baryon with the quantum number is considered as a molecular state composed of a baryon and meson. The partial decay widths of the molecular state into and final states through hadronic loops are evaluated with the help of the effective Lagrangians. The partial widths for the and transitions are evaluated at 1.50–1.02 keV and 17.56–24.91 keV, respectively, which may be accessible for the LHCb. Based on our results, we argue that an experimental determination of the radiative decay width of is important for the understanding of its intrinsic properties.

Understanding the structures of hidden-charm pentaquarks in a simple model

We discuss the possible interpretations and JP assignments for the LHCb Pc(4312), Pc(4440), and Pc(4457) pentaquark states in a simple chromomagnetic model, Hsplitting=−∑i<jCijλi⋅λjσi⋅σj and Hdecay=const. We find that both the spectrum and decay properties can be understood by assuming that they are (uud)8c(cc‾)8c states. The JP=3/2− assignment for the Pc(4312) is different from the JP=1/2− assignment in the naive ΣcD‾ molecule picture. If the former assignment is confirmed, the possible implication of the (uud)8c(cc‾)8c structure is discussed. The search for the predicted pentquark states is also called for.

Pc(4457)+ , Pc(4440)+ , and Pc(4312)+ : Molecules or compact pentaquarks?

In a chromomagnetic model, we analyse the properties of the newly observed $P_c(4457)^+$, $P_c(4440)^+$, and $P_c(4312)^+$ states. We estimate the masses of the $(uud)_{8_c}(c\bar{c})_{8_c}$ and $(uds)_{8_c}(c\bar{c})_{8_c}$ pentaquark states by considering the isospin breaking effects. Their values are determined by calculating mass distances from the $\Sigma_c^{++}D^-$ and $\Xi_c^{\prime+}D^-$ thresholds, respectively. It is found that the isospin breaking effects on the spectrum are small. From the uncertainty consideration and the rearrangement decay properties in a simple model, we find that it is possible to assign the $P_c(4457)^+$, $P_c(4440)^+$, and $P_c(4312)^+$ as $J^P=3/2^-$, $1/2^-$, and $3/2^-$ pentaquark states, respectively. The assignment in the molecule picture can be different, in particular for the $P_c(4312)^+$. The information from open-charm channels, e.g. ${\cal B}[P_c\to\Sigma_c^{++}D^-]/{\cal B}[P_c\to J/\psi p]$, will play an important role in distinguishing the inner structures of the $P_c$ states. Discussions and predictions based on the calculations are also given.

Analyzing Xi (1620) in the molecule picture in the Bethe\u2013Salpeter equation approach

In this work, we assume that the observed state Xi (1620) is a s-wave Lambda {bar{K}} or Sigma {bar{K}} bound state. Based on this molecule picture, we establish the Bethe–Salpeter equations for Xi (1620) in the ladder and instantaneous approximations. We solve the Bethe–Salpeter equations for the Lambda {bar{K}} and Sigma {bar{K}} systems numerically and find that the Xi (1620) can be explained as Lambda {bar{K}} and Sigma {bar{K}} bound states with J^P=1/2^-, respectively. Then we calculate the decay widths of Xi (1620)rightarrow Xi pi in these two different molecule pictures systems, respectively.

Material Flow in Cutting of Metals Affected by Low Frequency Modulation

This paper has been exhibited for different part of the misshapening field, material stream, and mechanics of chip division in cutting of metals with superimposed low-recurrence tweak (1000HZ) are described at the mesoscale utilizing rapid imaging and molecule picture of velocimetry (PIV).

Quantum Coherence and Temperature Dependence of the Anomalous State of Nanoconfined Water in Carbon Nanotubes.

X-ray Compton scattering measurements of the electron momentum distribution in water confined in both single-walled and double-walled carbon nanotubes (SWNT and DWNT), as a function of temperature and confinement size are presented here together with earlier measurements of the proton momentum distribution in the same systems using neutron Compton scattering. These studies provide a coherent picture of an anomalous state of water that exists because of nanoconfinement. This state cannot be described by the weakly interacting molecule picture. It has unique transport properties for both protons and water molecules. We suggest that knowledge of the excitation spectrum of this state is needed to understand the enhanced flow of water in cylinders with diameters on the order of 20 Å.

Production ofY(4260)as a hadronic molecule state ofD¯D1+c.c.ine+e−annihilations

We study the $Y(4260)$ production mechanism in $e^+e^-$ annihilations in the framework of hadronic molecules and investigate the consequence of such a picture in different decay channels. In the hadronic molecule picture the $Y(4260)$ is described as a mixture state composed of a long-ranged $\bar{D}D_1(2420)+c.c.$ molecule state and a compact $c\bar{c}$ component. We show that the compositeness relation can still provide a reasonable constraint on the wavefunction renormalization parameter due to the dominance of the molecular component. Such a mechanism can be regarded as a natural consequence of the heavy quark spin symmetry (HQSS) breaking. This study elaborates the molecular picture for the $Y(4260)$ in the $e^+e^-$ annihilations and affirms that the cross section lineshape of $e^+e^-\to \bar{D}D^*\pi+c.c.$ in the vicinity of the $Y(4260)$ should have a nontrivial behavior. In this framework we predict that the upper limit of the $Y(4260)$ leptonic decay width is about 500 eV. We also investigate the coupling for $D_1(2420)\to D^*\pi$ in the $^3P_0$ quark model and examine the possible HQSS breaking effects due to the deviation from the $|^1P_1\rangle$ and $|^3P_1\rangle$ ideal mixing. This will in turn provide a constraint on the HQSS breaking coupling for the $Y(4260)$ to $\bar{D}D_1(2420)+c.c.$ via its $c\bar{c}$ component.

Radiative decays of the neutralZc(3900)

We study the radiative decays of the $Z_c(3900)^0$ in a hadronic molecule picture, where the $Z_c(3900)$ is treated as a $D \bar{D}^\ast +c.c$ hadronic molecule. The partial widths of $\Gamma(Z_c(3900)^0 \to \gamma \eta_c(2S))$ and $\Gamma(Z_c(3900)^0 \to \gamma \chi_{c0})$ are predicted to be of order 10 keV and the cross sections for $\sigma(e^+ e^- \to \pi^0 Z_c(3900) \to \pi^0 \gamma \eta_c(2S))$ and $\sigma(e^+ e^- \to \pi^0 Z_c(3900) \to \pi^0 \gamma \chi_{c0})$ are of order 0.1 pb at 4.23 GeV, which may be accessible for the BESIII and forthcoming BelleII.

Vibrational Spectroscopy and Phonon-Related Properties of the L-Aspartic Acid Anhydrous Monoclinic Crystal.

The infrared absorption and Raman scattering spectra of the monoclinic P21 l-aspartic acid anhydrous crystal were recorded and interpreted with the help of density functional theory (DFT) calculations. The effect of dispersive forces was taken into account, and the optimized unit cells allowed us to obtain the vibrational normal modes. The computed data exhibits good agreement with the measurements for low wavenumbers, allowing for a very good assignment of the infrared and Raman spectral features. The vibrational spectra of the two lowest energy conformers of the l-aspartic molecule were also evaluated using the hybrid B3LYP functional for the sake of comparison, showing that the molecular calculations give a limited description of the measured IR and Raman spectra of the l-aspartic acid crystal for wavenumbers below 1000 cm(-1). The results obtained reinforce the need to use solid-state calculations to describe the vibrational properties of molecular crystals instead of calculations for a single isolated molecule picture even for wavenumbers beyond the range usually associated with lattice modes (200 cm(-1) < ω < 1000 cm(-1)).

Electron hopping at the Si(111):B-3surface: Insight from local impurity spectroscopy

Boron vacancies at the Si(111):B-$\sqrt{3}$ surface are model systems in the comprehension of strongly correlated semiconductor surfaces. By using scanning tunneling spectroscopy, the origin of the single-vacancy electronic structure is addressed. It is shown to originate from the localization of a well-identified dangling-bond surface state with significant B character. The bivacancy defect, which is characterized by energy-split bonding and antibonding states, is interpreted within the textbook diatomic molecule picture. From the hopping parameter, we determine the bandwidth of the surface state from which the impurity state derives and evaluate the strength of many-body effects. Our analysis supports the realization of the Mott-Hubbard insulator state in half-filled dangling-bond surface states on $\sqrt{3}$-reconstructed surfaces, as proposed recently for SiC(0001), Sn/Ge(111), and Sn/Si(111).

Tetraquark bound states in a Bethe–Salpeter approach

We determine the mass of tetraquark bound states from a coupled system of covariant Bethe–Salpeter equations. Similar in spirit to the quark–diquark model of the nucleon, we approximate the full four-body equation for the tetraquark by a coupled set of two-body equations with meson and diquark constituents. These are calculated from their quark and gluon substructure using a phenomenologically well-established quark–gluon interaction. For the lightest scalar tetraquark we find a mass of the order of 400 MeV and a wave function dominated by the pion–pion constituents. Both results are in agreement with a meson molecule picture for the f0(600). Our results furthermore suggest the presence of a potentially narrow all-charm tetraquark in the mass region 5–6 GeV.

CHIRAL DYNAMICS, STRUCTURE OF Λ(1405), AND $\bar{K}N$ PHENOMENOLOGY

We investigate the structure of the Λ(1405) resonance and [Formula: see text] phenomenology in the perspective of chiral SU(3) dynamics. Utilizing the chiral coupled-channel approach which well describes the [Formula: see text] scattering observable, we perform three different analyses to clarify the structure of the Λ(1405) resonance. The results consistently indicate the meson-baryon molecule picture of the Λ(1405). We argue the consequence of the chiral dynamics in [Formula: see text] phenomenology and the antikaon bound state in nucleus, emphasizing the important role of the strong πΣ interaction.

Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy

Two-photon absorption (2PA) spectroscopy in the range from 7 to 10 eV provides new insight on the electronic structure of liquid water. Continuous 2PA spectra are obtained via the pump-probe technique, using broadband probe pulses to record the absorption at many wavelengths simultaneously. A preresonance enhancement of the absolute 2PA cross section is observed when the pump-photon energy increases from 4.6 to 6.2 eV. The absorption cross section also depends on the relative polarization of the pump and probe photons. The variation of the polarization ratio across the spectrum reveals a detailed picture of the 2PA and indicates that at least four different transitions play a role below 10 eV. Theoretical polarization ratios for the isolated molecule illustrate the value of the experimental polarization measurement in deciphering the 2PA spectrum and provide the framework for a simple simulation of the liquid spectrum. A more comprehensive model goes beyond the isolated molecule picture and connects the 2PA spectrum with previous one-photon absorption, photoelectron, and x-ray absorption spectroscopy measurements of liquid water. Previously unresolved, overlapping transitions are assigned for the first time. Finally, the electronic character of the vertical excited states is related to the energy-dependent ionization mechanism of liquid water.

What can we learn from the decay of NX(1625) in the molecule picture?

Considering two assumptions on the molecular state, i.e. the S-wave Λ̄–K- and S-wave Σ̄0–K- molecular states, we study the possible decays of N̄X(1625) that include N̄X(1625)→K-Λ̄,π0p̄,ηp̄,π-n̄. Our results indicate that (1) if N̄X(1625) is the Λ̄–K- molecular state, K-Λ̄ is the main decay mode of N̄X(1625), and the branching ratios of the rest decay modes are tiny; (2) if N̄X(1625) is the Σ̄0–K- molecular state, the branching ratio of N̄X(1625)→K-Λ̄ is one or two orders smaller than that of N̄X(1625)→π0p̄,ηp̄,π-n̄. Thus the search for N̄X(1625)→π0p̄,ηp̄,π-n̄ will be helpful to shed light on the nature of N̄X(1625).