The possible BπB\pi molecular state and its radiative decay

Recently, several exotic bosons have been confirmed as multi-quark states, but there are violent disputes about their inner structures, namely if they are molecular states or tetraquarks, or even mixtures of the two structures. It would be interesting to experimentally search for non-strange four-quark states with open charm or bottom which are lighter than $\Lambda_c$ or $\Lambda_b$. Reasonable arguments indicate that they are good candidates of pure molecular states $D\pi$ or $B\pi$ because pions are the lightest boson. Both $B\pi$ and $D\pi$ bound states do not decay via strong interaction. The $B\pi$ molecule may decay into $B^*$ by radiating a photon, whereas $D\pi$ molecule can only decay via weak interaction. In this paper we explore the mass spectra of $B\pi$ molecular statesby solving the corresponding B-S equation. Then the rate of radiative decay $|\frac{3}{2},\frac{1}{2}\rangle\to B^*\gamma$ is calculated and our numerical results indicate that the processes can be measured by the future experiment. We also briefly discuss the $D\pi$ case, due to the constraint of the final state phase space, it can only decay via weak interaction.Comment: 12 pages, 3 figures, 3 table

4,4′,6,6′-Tetra­bromo-2,2′-(2,8-diazonia-5-azanona-1,8-diene-1,9-diyl)diphenolate

In the zwitterionic title compound, C18H17Br4N3O2, the two salicylaldimine groups form a dihedral angle of 51.94 (2)° and the dihedral angle between the aromatic ring planes is 51.14 (2)°. One of the C atoms adjacent to the aza N atom is disordered over two positions; the site-occupancy factors are 0.51 (1) and 0.49 (1). There are two strong intra­molecular N—H⋯O hydrogen bonds in the mol­ecule

2,4-Dibromo-6-{(E)-[(R)-1-phenyl­ethyl]imino­meth­yl}phenol

In the title Schiff base, C15H13Br2NO, the benzene and phenyl rings form a dihedral angle of 75.18 (13)°. The N=C bond length of 1.263 (6) Å is shorter than of the N—C bond [1.476 (5) Å], indicating a double bond. In the crystal, there is some pseudosymmetry. This occurs because most of the two mol­ecules are centrosymmetrically related. The mol­ecular structure is stabilized by intra­molecular O—H⋯N hydrogen bonds

4,4′-Dimethyl-2,2′-[1,2-phenyl­enebis(nitrilo­methyl­idyne)]diphenol

In the title Schiff base, C22H20N2O2, the benzene ring forms dihedral angles of 53.92 (1) and 3.62 (1)° with the two salicylaldimine groups. There are two strong O—H⋯N intra­molecular hydrogen bonds. The crystal packing is stabilized by weak inter­molecular C—H⋯O hydrogen bonds and π–π stacking inter­actions (average distance 3.39 Å)

1,2-Bis[4-(1H-imidazol-1-yl)benzyl­idene]hydrazine

The title compound, C20H16N6, is centrosymmetric with the mid-point of the N—N bond located on an inversion center. The imidazole ring is oriented at a dihedral angle of 28.03 (6)° with respect to the attached benzene ring. In the crystal, molecules are linked via C—H⋯N interactions

Network Representation Learning: From Traditional Feature Learning to Deep Learning

Network representation learning (NRL) is an effective graph analytics technique and promotes users to deeply understand the hidden characteristics of graph data. It has been successfully applied in many real-world tasks related to network science, such as social network data processing, biological information processing, and recommender systems. Deep Learning is a powerful tool to learn data features. However, it is non-trivial to generalize deep learning to graph-structured data since it is different from the regular data such as pictures having spatial information and sounds having temporal information. Recently, researchers proposed many deep learning-based methods in the area of NRL. In this survey, we investigate classical NRL from traditional feature learning method to the deep learning-based model, analyze relationships between them, and summarize the latest progress. Finally, we discuss open issues considering NRL and point out the future directions in this field

Bis[μ-3-(1H-benzimidazol-2-yl)benzoato]dicopper(I)

The dimeric title complex, [Cu2(C14H9N2O2)2], resides on a center of symmetry. In the crystal, the mol­ecules are packed via π–π stacking inter­actions alternating between imidazole and benzene rings [mean inter­planar distances = 3.754 (3) and 3.624 (3) Å]. An inter­molecular N—H⋯O hydrogen bond links the dimers together. The two-coordinate CuI atom displays an O—Cu—N bond angle of 176.3 (2)°. The Cu⋯Cu distance within the dimer is 5.100 (2) Å