Narrow States Research Articles

Diabatic description of bottomoniumlike mesons

We apply the diabatic approach, specially suited for a QCD based study of conventional (quark-antiquark) and unconventional (quark-antiquark + meson-meson) meson states, to the description of hidden-bottom mesons. A spectral analysis of the $I=0$, $J^{++}$ and $1^{--}$ resonances with masses up to about $10.8$ GeV is carried out. Masses and widths of all the experimentally known resonances, including conventional and unconventional states, can be well reproduced. In particular, we predict a significant $B\bar{B}^{\ast}$ component in $\Upsilon(10580)$. We also predict the existence of a not yet discovered unconventional $1^{++}$ narrow state, with a significant $B_{s}\bar{B}_{s}^{\ast}$ content making it to decay into $\Upsilon(1S)\phi$, whose experimental discovery would provide definite support to our theoretical analysis.

Excited J−− meson resonances at the SU(3) flavor point from lattice QCD

We present the first calculation within lattice QCD of excited light meson resonances with $J^{PC} = 1^{--}$, $2^{--}$ and $3^{--}$. Working with an exact SU(3) flavor symmetry, for the singlet representation of pseudoscalar-vector scattering, we find two $1^{--}$ resonances, a lighter broad state and a heavier narrow state, a broad $2^{--}$ resonance decaying in both $P$- and $F$-waves, and a narrow $3^{--}$ state. We present connections to experimental $\omega^\star_J, \phi^\star_J$ resonances decaying into $\pi \rho$, $K\bar{K}^*$, $\eta \omega$ and other final states.

Probing Folded Proteins and Intact Protein Complexes by Desorption Electrospray Ionization Mass Spectrometry.

Native mass spectrometry (MS) enables the study of intact proteins as well as noncovalent protein-protein and protein-ligand complexes in their biological state. In this work, we present the application of a Waters desorption electrospray ionization (DESI) source with a prototype spray emitter for rapid surface measurements of folded and native protein structures. A comparison of DESI spray solvent shows that adding 50% methanol to 200 mM ammonium acetate solution does not reduce its performance in preserving folded protein structures. Instead, improved signal-to-noise (S/N) ratio is obtained, and less adducted peaks are detected by using this uncommon native MS solvent system. The standard DESI design with an inlet tube allows optimization of sampling temperature conditions to improve desolvation and therefore S/N ratio. Furthermore, tuning the inlet temperature enables the control and study of unfolding behavior of proteins from surface samples. The optimized condition for native DESI has been applied to several selected proteins and protein complexes with the molecular weight ranging from 8.6 to 66.4 kDa. Ions of folded proteins with narrow charge state distribution (CSD), or peaks showing noncovalent-bond-assembled intact protein complexes, are observed in the spectra. Evidence for the structural refolding of denatured proteins and protein complexes sampled with native solvent highlights the need for care when interpreting DESI native MS data, particularly for proteins with stable native structures.

Study of the decays of S -wave D¯*K* hadronic molecules: The scalar X0(2900) and its spin partners X˜J(J=1,2)

In this work, we investigate the decays of the fully open-flavor tetraquark state ${X}_{0}(2900)$ which was observed by the LHCb collaboration very recently. By using an effective Lagrangian approach, the partial widths of ${X}_{0}(2900)$ are estimated, where ${X}_{0}(2900)$ is assumed to be an $S$-wave ${\overline{D}}^{*}{K}^{*}$ hadronic molecule with $I=0$. It is found that the estimated results are in agreement with the experimental observations. Moreover, we also predict the decay behaviors of the other unobserved ${\stackrel{\texttildelow{}}{X}}_{J(J=1,2)}$, which are the spin partners of the ${X}_{0}(2900)$ in the $S$-wave ${\overline{D}}^{*}{K}^{*}$ picture. It is pointed out that the ${\stackrel{\texttildelow{}}{X}}_{1}$ state with $I=0$ is a broad state with the width more than 100 MeV, while another ${\stackrel{\texttildelow{}}{X}}_{2}$ state with $I=0$ is a narrow state with the width approaching half of that for the ${X}_{0}(2900)$. In addition, our results also show that the ${\overline{D}}^{*}K$ mode is expected to be the dominant decay mode for both ${\stackrel{\texttildelow{}}{X}}_{1}$ and ${\stackrel{\texttildelow{}}{X}}_{2}$. Searching for those unobserved ${\stackrel{\texttildelow{}}{X}}_{J(J=1,2)}$ in the future experiments might be helpful to understand the nature of ${X}_{0}(2900)$.

Systematics of fully heavy tetraquarks

In this work, we systematically study the mass spectrum of the fully heavy tetraquark in an extended chromomagnetic model, which includes both color and chromomagnetic interactions. Numerical results indicate that the energy level is mainly determined by the color interaction, which favors the color-sextet $|(QQ{)}^{{6}_{c}}(\overline{Q}\overline{Q}{)}^{{\overline{6}}_{c}}⟩$ configuration over the color-triplet $|(QQ{)}^{{\overline{3}}_{c}}(\overline{Q}\overline{Q}{)}^{{3}_{c}}⟩$ one. The chromomagnetic interaction mixes the two color configurations and gives small splitting. The ground state is always dominated by the color-sextet configuration. We find no stable state below the lowest heavy quarkonium pair thresholds. Most states may be wide since they have at least one $S$-wave decay channel into two $S$-wave mesons. One possible narrow state is the ${1}^{+}$ $bb\overline{b}\overline{c}$ state with a mass 15719.1 MeV. It is just above the ${\ensuremath{\eta}}_{b}{\overline{B}}_{c}$ threshold. But this channel is forbidden because of the conservation of the angular momentum and parity.

Tandem surface-induced dissociation of protein complexes on an ultrahigh resolution platform

We describe instrumentation for conducting tandem surface-induced dissociation (tSID) of native protein complexes on an ultrahigh resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The two stages of SID are accomplished with split lenses replacing the entrance lenses of the quadrupole mass filter (stage 1, referred to herein as SID-Q) and the collision cell (stage 2, Q-SID). After SID-Q, the scattered projectile ions and subcomplexes formed in transit traverse the pre-filter prior to the mass-selecting quadrupole, providing preliminary insights into the SID fragmentation kinetics of noncovalent protein complexes. The isolated SID fragments (subcomplexes) are then fragmented by SID in the collision cell entrance lens (Q-SID), generating subcomplexes of subcomplexes. We show that the ultrahigh resolution of the FT-ICR can be used for deconvolving species overlapping in m/z, which are particularly prominent in tandem SID spectra due to the combination of symmetric charge partitioning and narrow product ion charge state distributions. Various protein complex topologies are explored, including homotetramers, homopentamers, a homohexamer, and a heterohexamer.

Detecting Anomalies in the 2020 US Presidential Election Votes with Benford’s Law

This study applies Benford’s law to detect anomalies in county-level vote data for the 2020 US presidential election. Most prominent distribution violations are observed with Republican vote counts in blue states, all vote counts in states won by the Democratic candidate, and Democratic vote counts in swing states. Distributions are anomalous in swing states won by the Democratic nominee and not anomalous in swing states won by the Republican nominee. The results are robust to two-digit analysis, Monte Carlo simulations of p-values, broad or narrow swing state definitions, and when compared to distributions observed in 2008, 2012, and 2016 elections.

Study on Fano resonance sensing characteristics of double-baffle MDM waveguide coupled disk cavity with absorption material

A metal-dielectric-metal (MDM) waveguide coupled disk cavity structure with bimetallic baffle is proposed, which bases on the transmission characteristics of surface plasmon polaritons (SPPs) in subwavelength structure, and the absorption material InGaAsP is filled in the Fabry–Perot (F-P) cavity and disk cavity. The Fano resonance is an asymmetric spectral line formed by the destructive interference between the wide continuous state generated by the F-P resonator and the narrow discrete state interference generated by the disk cavity. Based on the coupled mode theory, the formation mechanism of the Fano resonance of the structure is qualitatively analyzed. The structure was simulated by finite element method to quantitatively analyze the influence of structural parameters and absorption material InGaAsP on the refractive index sensing characteristics. The proposed sensor yields sensitivity higher than 1360 nm/refractive index unit (RIU) and a figure of merit of [Formula: see text] by optimizing the geometry parameters and filling the absorption material InGaAsP. This structure has potential applications for high integration of nanosensors, slow-light devices, and nano-optical switches.

QQs¯s¯ tetraquarks in the chiral quark model

The low-lying $S$-wave $QQ\bar{s}\bar{s}$ ($Q=c, b$) tetraquark states with $IJ^P=00^+$, $01^+$ and $02^+$ are systematically investigated in the framework of complex scaling range of chiral quark model. Every structure including meson-meson, diquark-antidiquark and K-type configurations, and all possible color channels in four-body sector are considered by means of a commonly extended variational approach, Gaussian expansion method. Several narrow and wide resonance states are obtained for $cc\bar{s}\bar{s}$ and $bb\bar{s}\bar{s}$ tetraquarks with $IJ^P=00^+$ and $02^+$. Meanwhile, narrow resonances for $cb\bar{s}\bar{s}$ tetraquarks are also found in $IJ^P=00^+$, $01^+$ and $02^+$ states. These results confirm the possibility of finding hadronic molecules with masses $\sim\,0.6\,\text{GeV}$ above the noninteracting hadron-hadron thresholds.

Understanding the newly observed Ξc0 states through their decays

Inspired by the newly observed $\Xi_c^0$ states by the LHCb Collaboration, we investigate the OZI-allowed two-body strong decays of the $\lambda$-mode $1P$ wave $\Xi'_c$ states within the chiral quark model. Our results indicate that: (i) the newly observed states $\Xi_c(2923)^0$ and $\Xi_c(2939)^0$ are good candidates of the $\lambda$-mode $1P$ wave $\Xi'_c$ states with the spin-parity $J^P=3/2^-$, namely $|^4P_{\lambda}3/2^-\rangle$ and $|^2P_{\lambda}3/2^-\rangle$, respectively. (ii) The another newly observed state $\Xi_c(2965)^0$ mostly corresponds to the $\lambda$-mode $1P$-wave $\Xi'_c$ state with the spin-parity $J^P=5/2^-$, namely $|^4P_{\lambda}5/2^-\rangle$. (iii) For the two $\lambda$-mode $J^P=1/2^-$ mixed states, the $|P_{\lambda}~1/2^-\rangle_1$ is a narrow state with a width of $\Gamma\sim15$ MeV and mainly decays into $\Xi'_c\pi$; while the $|P_{\lambda}~1/2^-\rangle_2$ state has a width of $\Gamma\sim52$ MeV and dominantly decays into $\Xi_c\pi$ and $\Lambda_cK$ channels. If the broad structure around $2880$ MeV observed at LHCb arises from the new $\Xi^0_c$ state, this state is very likely to be the $|P_{\lambda}~1/2^-\rangle_2$ state.

Ca24Al28O64]4+(4e−) electrides ceramic with high-electron concentration rapidly fabricated by spark plasma sintering of Ca, Al organic powder precursor in spark plasma sintering

The electrides of [Ca24Al28O64]4+(4e−) (C12A7:e−) was quickly fabricated by Ca, Al organic powder precursor through spark plasma sintering (SPS) at 750 °C for 10 min. There exist a large amount of reducing gas CO generated by heating Ca, Al organic powder acting as a perfect reducing agent in the high-energy DC pulse current and DC electric field of the SPS. By analyzing the phase, elements, structural composition, and electronic state of the sample, it is found that the phase and elemental composition of the sample meet the standard C12A7:e− and the density of the sample is more than 99%. The EPR results show that the sample has a sharp absorption peak at a magnetic field strength of about 352 mT, and the ratio of the maximum value to the minimum amount of the absorption peak is 2.67. This EPR curve with Dyson characteristics indicates that there is a high density of unpaired electrons inside the sample. The sample showed a significant ultraviolet absorption peak at 2.5 eV, and the calculated electron concentration of the sample reached 2.3 × 1021cm−3. TG/DTA, Raman spectroscopy, and XPS result further fully proved the successful fabrication of C12A7:e−. The electronic structure of C12A7:e− calculated using the first-principles show that the CCB of C12A7:e− not only traverses the Fermi surface as a whole, but also shows a narrower state with a smaller effective mass of electron transition, and the energy between CCB and FCB is 0.68eV. This indicates that C12A7:e− has excellent electrical transport characteristics like typical metals, which mainly from the contribution of s-state electrons of Ca atoms and p-state electrons of Al atoms. The theoretical results support our experiments. This fabricating method makes rapid large-scale production of C12A7:e− with high electron concentration possible.

From triply charmed dibaryons to pentaquark states: A model-independent way to determine the spins of the Pc(4440) and Pc(4457)

The LHCb collaboration has recently observed three narrow pentaquark states --- the $P_c(4312)$, $P_c(4440)$, and $P_c(4457)$ ---that are located close to the $\bar{D} \Sigma_c$ and $\bar{D}^* \Sigma_c$ thresholds. Among the so-far proposed theoretical interpretations for these pentaquarks, the molecular hypothesis seems to be the preferred one. Nevertheless, in the molecular picture the spins of the $P_c(4440)$ and $P_c(4457)$ have not been unambiguously determined yet. In this letter we point out that heavy antiquark-diquark symmetry induces a model-independent relation between the spin-splitting in the masses of the $P_c(4440)$ and $P_c(4457)$ $\bar{D}^* \Sigma_c$ pentaquarks and the corresponding splitting for the $0^+$ and $1^+$ $\Xi_{cc} \Sigma_c$ triply charmed dibaryons. This is particularly relevant owing to a recent lattice QCD prediction of the $1^+$ triply charmed dibaryon, which suggests that a calculation of the mass of its $0^+$ partner might be within reach. This in turn would reveal the spins of the $P_c(4440)$ and $P_c(4457)$ pentaquarks, providing a highly nontrivial test of heavy-quark symmetry and the molecular nature of the pentaquarks. Furthermore, the molecular interpretation of the hidden-charm pentaquarks implies the existence of a total of ten triply charmed dibaryons as $\Xi_{cc}^{(*)} \Sigma_c^{(*)}$ molecules, which, if confirmed in the lattice, will largely expand our understanding of the non-perturbative strong interaction in the heavy-quark sector.

Toward establishing the low-lying P -wave Σb states

In the present work, we analyze the $P$-wave singly-heavy baryon spectrum belonging to $\mathbf{6}_F$ by combining the observations of the heavy baryon states, and restudy the strong decays of the $1P$ wave $\Sigma_b$ states within the $j$-$j$ coupling scheme using the chiral quark model. We obtain that: (i) the structure $\Sigma_b(6097)$ observed in the $\Lambda_b\pi$ final state may arise from the overlapping of $\Sigma_b|J^P=\frac{3}{2}^-,2\rangle$ and $\Sigma_b|J^P=\frac{5}{2}^-,2\rangle$. (ii) The broad structure $\Sigma_b(6072)$ observed in the $\Lambda_b\pi\pi$ final state may arise from the overlapping of $\Sigma_b|J^P=\frac{1}{2}^-,1\rangle$ and $\Sigma_b|J^P=\frac{3}{2}^-,1\rangle$. (iii) The missing state $\Sigma_b|J^P=\frac{1}{2}^-,0\rangle$ is most likely to be a narrow state with a width of $\Gamma\sim10$ MeV, and mainly decays into $\Lambda_b\pi$ channel.

Single-particle resonant states with Green’s function method * * Partly supported by the Physics Research and Development Program of Zhengzhou University (32410217) and the National Natural Science Foundation of China (11505157, 11875225)

This study employs the relativistic mean field theory with the Green's function method to study the single-particle resonant states. In contrast to our previous work [Phys. Rev. C, 90: 054321 (2014)], the resonant states are identified by searching for the poles of Green's function or the extremes of the density of states. This new approach is highly effective for all kinds of resonant states, no matter whether they are broad or narrow. The dependence on the space size for the resonant energies, widths, and the density distributions in the coordinate space has been checked and was found to be very stable. Taking 120Sn as an example, four new broad resonant states , , , and were observed, and the accuracy for the width of the very narrow resonant state was highly improved to MeV. Further, our results are very close to those obtained using the complex momentum representation method and the complex scaling method.

The structure of lipid nanodisc-reconstituted TRPV3 reveals the gating mechanism.

Transient receptor potential vanilloid subfamily member 3 (TRPV3) is a temperature-sensitive cation channel. Previous cryo-EM analyses of TRPV3 in detergent micelles or amphipol proposed that the lower gate opens by α-to-π helical transitions of the nearby S6 helix. However, it remains unclear how physiological lipids are involved in the TRPV3 activation. Here we determined the apo state structure of mouse (Mus musculus) TRPV3 in a lipid nanodisc at 3.3 Å resolution. The structure revealed that lipids bound to the pore domain stabilize the selectivity filter in the narrow state, suggesting that the selectivity filter of TRPV3 affects cation permeation. When the lower gate is closed in nanodisc-reconstituted TRPV3, the S6 helix adopts the π-helical conformation without agonist- or heat-sensitization, potentially stabilized by putative intra-subunit hydrogen bonds and lipid binding. Our findings provide insights into the lipid-associated gating mechanism of TRPV3.

Excited-state trions in two-dimensional materials

Using the complex scaling and the stabilization method combined with the stochastic variational approach, we have shown that there are narrow resonance states in two-dimensional three particle systems of electrons and holes interacting via a screened Coulomb interaction. These resonances are loosely bound systems of excited state excitons with a third particle circling around them. Recent experimental studies of excited state trions might be explained and identified by these resonant states.

Following Structural Changes by Thermal Denaturation Using Trapped Ion Mobility Spectrometry-Mass Spectrometry.

The behavior of biomolecules as a function of the solution temperature is often crucial to assessing their biological activity and function. While heat-induced changes of biomolecules are traditionally monitored using optical spectroscopy methods, their conformational changes and unfolding transitions remain challenging to interpret. In the present work, the structural transitions of bovine serum albumin (BSA) in native conditions (100 mM aqueous ammonium acetate) were investigated as a function of the starting solution temperature (T ∼ 23-70 °C) using a temperature-controlled nanoelectrospray ionization source (nESI) coupled to a trapped ion mobility spectrometry-mass spectrometry (TIMS-MS) instrument. The charge state distribution of the monomeric BSA changed from a native-like, narrow charge state ([M + 12H]12+ to [M + 16H]16+ at ∼23 °C) and narrow mobility distribution toward an unfolded-like, broad charge state (up to [M + 46H]46+ at ∼70 °C) and broad mobility distribution. Inspection of the average charge state and collision cross section (CCS) distribution suggested a two-state unfolding transition with a melting temperature Tm ∼ 56 ± 1 °C; however, the inspection of the CCS profiles at the charge state level as a function of the solution temperature showcases at least six structural transitions (T1-T7). If the starting solution concentration is slightly increased (from 2 to 25 μM), this method can detect nonspecific BSA dimers and trimers which dissociate early (Td ∼ 34 ± 1 °C) and may disturb the melting curve of the BSA monomer. In a single experiment, this technology provides a detailed view of the solution, protein structural landscape (mobility vs solution temperature vs relative intensity for each charge state).

CP asymmetry from hadronic charm rescattering in B± → π−π+π± decays at the high mass region

A model for the B±→π−π+π± decay amplitude is proposed to study the large CP violation observed at the high mass region of the Dalitz plane. A short distance b→u amplitude with the weak phase γ is considered together with the contribution of a hadronic charm loop and a s-wave DD¯→ππ rescattering. In the model, the χc0 appears as a narrow resonant state of the DD¯ system below threshold. It is introduced in an unitary two channel S-matrix model of the coupled DD¯ and ππ channels, where the χc0 complex pole in DD¯ channel shows its signature in the off-diagonal matrix element and in the associated DD¯→ππ transition amplitude. The strong phase of the resulting decay amplitude has a sharp sign change at the DD¯ threshold, changing the sign of the CP asymmetry, as it is observed in the data. We conclude that the hadronic charm loop and rescattering mechanism are relevant to the broadening of the CP asymmetry around the χc0 resonance in the ππ channel. This novel mechanism provides a possible interpretation for the CP asymmetry challenging experimental result presented by the LHCb collaboration for the B±→π−π+π± decay in the high mass region.

Tunable Plasmonic System Based on a Slotted Side-Coupled Disk Resonator and Its Multiple Applications on Chip-Scale Devices

In this letter, based on the subwavelength metal-insulator-metal (MIM) waveguide embodying a baffle and a slotted side-coupled disk resonator (SSCDR) inserted with a metallic block is designed. The proposed structure is numerically investigated and analyzed by FEM method. Two sharp transmission peaks with high transmittance and asymmetrical line-shaped Fano resonances, originating from the interferences between the width continuum state supported by the MIM waveguide embodying a baffle and the narrow discrete state from the SSCDR, arise in its transmission spectrum. And multimode interference coupled mode theory (MICMT) is employed to analyze the proposed structure theoretically, which is consistent with the simulation results. Additionally, by adjusting the parameters of the structure, the resonant wavelengths of Fano resonances can be manipulated. Finally, the proposed structure is applied to nano-filters, refractive index (RI) sensors, temperature sensors and slow light devices, all showing high performance. It is believed that the proposed system can boost the development of highly integrated photonics and support substantial applications for nano-sensors, filters and slow light devices.

Characterizing quasibound states and scattering resonances

Characterizing quasibound states from coupled-channel scattering calculations can be a laborious task, involving extensive manual iteration and fitting. We present an automated procedure, based on the phase shift or S-matrix eigenphase sum, that reliably converges on a quasibound state (or scattering resonance) from some distance away. It may be used for both single-channel and multichannel scattering. It produces the energy and width of the state and the phase shift of the background scattering, and hence the lifetime of the state. It also allows extraction of partial widths for decay to individual open channels. We demonstrate the method on a very narrow state in the Van der Waals complex Ar--H$_2$, which decays only by vibrational predissociation, and on near-threshold states of $^{85}$Rb$_2$, whose lifetime varies over 4 orders of magnitude as a function of magnetic field.