An updated review of the new hadron states.

The past decades witnessed the golden era of hadron physics. Many excited open heavy flavor mesons and baryons have been observed since 2017. We shall provide an updated review of the recent experimental and theoretical progresses in this active field. Besides the conventional heavy hadrons, we shall also review the recently observed open heavy flavor tetraquark statesX(2900) andTcc+(3875)as well as the hidden heavy flavor multiquark statesX(6900),Pcs(4459)0,Zcs(3985)-,Zcs(4000)+, andZcs(4220)+. We will also cover the recent progresses on the glueballs and light hybrid mesons, which are the direct manifestations of the non-AbelianSU(3) gauge interaction of the Quantum Chromodynamics in the low-energy region.

Downregulation of a mitochondrial micropeptide, MPM, promotes hepatoma metastasis by enhancing mitochondrial complex I activity.

We and others have shown that MPM (micropeptide in mitochondria) regulates myogenic differentiation and muscle development. However, the roles of MPM in cancer development remain unknown. Here we revealed that MPM was downregulated significantly in human hepatocellular carcinoma (HCC) tissues and its decrease was associated with increased metastasis potential and HCC recurrence. Gain- and loss-of-function investigations disclosed that in vitro migration/invasion and in vivo liver/lung metastasis of hepatoma cells were repressed by restoring MPM expression and increased by silencing MPM. Mechanism investigations revealed that MPM interacted with NDUFA7. Mitochondrial complex I activity was inhibited by overexpressing MPM and enhanced by siMPM, and this effect of siMPM was attenuated by knocking down NDUFA7. The NAD+/NADH ratio, which was regulated by complex I, was reduced by MPM but increased by siMPM. Treatment with the NAD+ precursor nicotinamide abrogated the inhibitory effect of MPM on hepatoma cell migration. Further investigations showed that miR-17-5p bound to MPM and inhibited MPM expression. miR-17-5p upregulation was associated with MPM downregulation in HCC tissues. These findings indicate that a decrease in MPM expression may promote hepatoma metastasis by increasing mitochondrial complex I activity and the NAD+/NADH ratio.

Strong decays of fully-charm tetraquarks into di-charmonia.

We study strong decays of the possible fully-charm tetraquarks recently observed by LHCb, and calculate their relative branching ratios through the Fierz rearrangement. Together with our previous QCD sum rule study, our results suggest that the broad structure around 6.2-6.8 GeV can be interpreted as an S-wave ccc¯c¯ tetraquark state with JPC=0++ or 2++, and the narrow structure around 6.9 GeV can be interpreted as a P-wave one with JPC=0-+ or 1-+. These structures were observed in the di-J/ψ invariant mass spectrum, and we propose to confirm them in the di-ηc,J/ψhc,ηcχc0, and ηcχc1 channels. We also propose to search for their partner states having the negative charge-conjugation parity in the J/ψηc,J/ψχc0,J/ψχc1, and ηchc channels.

A novel mitochondrial micropeptide MPM enhances mitochondrial respiratory activity and promotes myogenic differentiation.

Micropeptides belong to a class of newly identified small molecules with <100 amino acids in length, and their functions remain largely unknown. Here, we identified a novel muscle-enriched micropeptide that was localized to mitochondria (named MPM, micropeptide in mitochondria) and upregulated during in vitro differentiation of C2C12 myoblasts and in vivo early postnatal skeletal muscle development, and muscle regeneration after cardiotoxin (CTX) damage. Downregulation of MPM was observed in the muscular tissues of tibial muscular dystrophy and Duchenne muscular dystrophy patients. Furthermore, MPM silencing inhibited the differentiation of C2C12 myoblasts into myotubes, whereas MPM overexpression stimulated it. MPM-/- mice exhibited smaller skeletal muscle fibers and worse muscle performance, such as decrease in the maximum grip force of limbs, the latency to fall off rotarod, and the exhausting swimming time. Muscle regeneration was also impaired in MPM-/- mice, as evidenced by lower expression of Pax7, MyoD, and MyoG after CTX injection and smaller regenerated myofibers, compared with wild-type mice. Mechanistical investigations based on both gain- and loss-of function studies revealed that MPM increased oxygen consumption and ATP production of mitochondria. Moreover, ectopic expression of PGC-1α, which can enhance mitochondrial respiration, attenuated the inhibitory effect of siMPM on myogenic differentiation. These results imply that MPM may promote myogenic differentiation and muscle fiber growth by enhancing mitochondrial respiratory activity, which highlights the importance of micropeptides in the elaborate regulatory network of both myogenesis and mitochondrial activity and implicates MPM as a potential target for muscular dystrophy therapy.

A review of the open charm and open bottom systems.

Since the discovery of the first charmed meson in 1976, many open-charm and open-bottom hadrons were observed. In 2003 two narrow charm-strange states [Formula: see text] and D s1(2460) were discovered by the BaBar and CLEO Collaborations, respectively. After that, more excited heavy hadrons were reported. In this work, we review the experimental and theoretical progress in this field.

Decoding the X(5568) as a Fully Open-Flavor sub[over ¯]d[over ¯] Tetraquark State.

We investigate the recent evidence for a charged X(5568) meson as an exotic open-flavor tetraquark state sub[over ¯]d[over ¯] with J^{P}=0^{+}/1^{+} in the framework of QCD sum rules. We use the color antisymmetric [3[over ¯]_{c}]_{su}⊗[3_{c}]_{b[over ¯]d[over ¯]} tetraquark currents in both scalar and axial-vector channels to perform evaluations and numerical analyses. Our results imply that the X(5568) can be interpreted as both the scalar sub[over ¯]d[over ¯] tetraquark state and the axial-vector one, which are in good agreement with the experimental measurement. We also discuss the possible decay patterns of the X(5568) and suggest to search for its neutral partner in the radiative decay into B_{s}^{0}γ and B_{s}^{*}γ, which can be used to determine its spin-parity quantum numbers. Moreover, we predict its charmed partner state around 2.55 GeV with the quark content suc[over ¯]d[over ¯] and J^{P}=0^{+}/1^{+}.

Towards Exotic Hidden-Charm Pentaquarks in QCD.

Inspired by P(c)(4380) and P(c)(4450) recently observed by LHCb, a QCD sum rule investigation is performed, by which they can be identified as exotic hidden-charm pentaquarks composed of an anticharmed meson and a charmed baryon. Our results suggest that P(c)(4380) and P(c)(4450) have quantum numbers J(P)=3/2(-) and 5/2(+), respectively. Furthermore, two extra hidden-charm pentaqurks with configurations D̅Σ(c)(*) and D̅(*)Σ(c)(*) are predicted, which have spin-parity quantum numbers J(P)=3/2(-) and J(P)=5/2(+), respectively. As an important extension, the mass predictions of hidden-bottom pentaquarks are also given. Searches for these partners of P(c)(4380) and P(c)(4450) are especially accessible at future experiments like LHCb and BelleII.

Oil-water separation property of polymer-contained wastewater from polymer-flooding oilfields in Bohai Bay, China.

In this study, the effects of gravitational settling time, temperature, speed and time of centrifugation, flocculant type and dosage, bubble size and gas amount were investigated. The results show that the simple increase in settling time and temperature is of no use for oil-water separation of the three wastewater samples. As far as oil-water separation efficiency is concerned, increasing centrifugal speed and centrifugal time is highly effective for L sample, and has a certain effect on J sample, but is not valid for S sample. The flocculants are highly effective for S and L samples, and the oil-water separation efficiency increases with an increase in the concentration of inorganic cationic flocculants. There exist critical reagent concentrations for the organic cationic and the nonionic flocculants, wherein a higher or lower concentration of flocculant would cause a decrease in the treatment efficiency. Flotation is an effective approach for oil-water separation of polymer-contained wastewater from the three oilfields. The oil-water separation efficiency can be enhanced by increasing floatation agent concentration, flotation time and gas amount, and by decreasing bubble size.