A survey of heavy–heavy hadronic molecules

The spectrum of hadronic molecules composed of heavy–antiheavy charmed hadrons has been obtained in our previous work. The potentials are constants at the leading order, which are estimated from resonance saturation. The experimental candidates of hadronic molecules, say X(3872), Y(4260), three P_c states and P_cs(4459), fit the spectrum well. The success in describing the pattern of heavy–antiheavy hadronic molecules stimulates us to give more predictions for the heavy–heavy cases, which are less discussed in literature than the heavy–antiheavy ones. Given that the heavy–antiheavy hadronic molecules, several of which have strong experimental evidence, emerge from the dominant constant interaction from resonance saturation, we find that the existence of many heavy–heavy hadronic molecules is natural. Among these predicted heavy–heavy states we highlight the DD^* molecule and the ${D}^{(* )}{{\rm{\Sigma }}}_{c}^{(* )}$ molecules, which are the partners of the famous X(3872) and P_c states. Quite recently, LHCb collaboration reported a doubly charmed tetraquark state, T_cc, which is in line with our results for the DD^* molecule. With the first experimental signal of this new kind of exotic states, the upcoming update of the LHCb experiment as well as other experiments will provide more chances of observing the heavy–heavy hadronic molecules.     

Precision measurements and tau neutrino physics in a future accelerator neutrino experiment

We investigate prospects of building a future accelerator-based neutrino oscillation experiment in China, including site selection, beam optimization and tau neutrino physics aspects. CP violation, non-unitary mixing and non-standard neutrino interactions are discussed. We simulate neutrino beam setups based on muon and beta decay techniques and compare Chinese laboratory sites by their expected sensitivities. A case study on the Super Proton–Proton Collider and the China JinPing Laboratory is also presented. It is shown that the muon-decay-based beam setup can measure the Dirac CP phase by about 14.2° precision at 1σ CL, whereas non-unitarity can be probed down to ∣α_ij∣ ≲ 0.37 (i ≠ j = 1, 2, 3) and non-standard interactions to $| {\epsilon }_{{\ell }{\ell }^{\prime} }^{m}| \lesssim $ 0.11 (${\ell }\ne {\ell }^{\prime} =e$, μ, τ) at 90% CL, respectively.     

Covalent hadronic molecules induced by shared light quarks

After examining Feynman diagrams corresponding to the ${\bar{D}}^{(* )}{{\rm{\Sigma }}}_{c}^{(* )}$, ${\bar{D}}^{(* )}{{\rm{\Lambda }}}_{c}$, ${D}^{(* )}{\bar{K}}^{* }$, and ${D}^{(* )}{\bar{D}}^{(* )}$ hadronic molecular states, we propose a possible binding mechanism induced by shared light quarks. This mechanism is similar to the covalent bond in chemical molecules induced by shared electrons. We use the method of QCD sum rules to calculate its corresponding light-quark-exchange diagrams, and the obtained results indicate a model-independent hypothesis: the light-quark-exchange interaction is attractive when the shared light quarks are totally antisymmetric so they obey the Pauli principle. We build a toy model with four parameters to formulize this picture and estimate binding energies of some possibly-existing covalent hadronic molecules. A unique feature of this picture is that the binding energies of the (I)J^P = (0)1⁺ $D{\bar{B}}^{* }/{D}^{* }\bar{B}$ hadronic molecules are much larger than those of the (I)J^P = (0)1⁺ ${{DD}}^{* }/\bar{B}{\bar{B}}^{* }$ ones, while the (I)J^P = (1/2)1/2⁺ $\bar{D}{{\rm{\Sigma }}}_{c}/\bar{D}{{\rm{\Sigma }}}_{b}/B{{\rm{\Sigma }}}_{c}/B{{\rm{\Sigma }}}_{b}$ hadronic molecules have similar binding energies.     

Ab initio calculation of the ground and first excited states of the lithium dimer

Based on a high level ab initio calculation which is carried out with the multireference configuration interaction method under the aug-cc-pVXZ (AVXZ) basis sets, X=T, Q, 5, the accurate potential energy curves (PECs) of the ground state ${\rm{X}}{}^{{\rm{1}}}{\rm{\Sigma }}_{g}^{+}$ and the first excited state ${\rm{A}}{}^{{\rm{1}}}{\rm{\Sigma }}_{u}^{+}$ of Li₂ are constructed. By fitting the ab initio potential energy points with the Murrell–Sorbie potential function, the analytic potential energy functions (APEFs) are obtained. The molecular bond length at the equilibrium (R_e), the potential well depth (D_e), and the spectroscopic constants (B_e, ω_e, α_e, and ω_eχ_e) for the ${\rm{X}}{}^{{\rm{1}}}{\rm{\Sigma }}_{g}^{+}$ state and the ${\rm{A}}{}^{{\rm{1}}}{\rm{\Sigma }}_{u}^{+}$ state are deduced from the APEFs. The vibrational energy levels of the two electronic states are obtained by solving the time-independent Schrödinger equation with the Fourier grid Hamiltonian method. All the spectroscopic constants and the vibrational levels agree well with the experimental results. The Franck–Condon factors (FCFs) corresponding to the transitions from the vibrational level (v′=0) of the ground state to the vibrational levels (v″=0–74) of the first excited state have been calculated. The FCF for the vibronic transition of ${\rm{A}}{}^{{\rm{1}}}{\rm{\Sigma }}_{u}^{+}$(v″=0) ←${\rm{X}}{}^{{\rm{1}}}{\rm{\Sigma }}_{g}^{+}$(v′=0) is the strongest. These PECs and corresponding spectroscopic constants provide reliable theoretical references to both the spectroscopic and the molecular dynamic studies of the Li₂ dimer.     

Mono-top signature from stop decay at the HE-LHC

Searching for the top squark(stop)is a key task to test the naturalness of SUSY.Different from stop pair production,single stop production relies on its electroweak properties and can provide some unique signatures.Following the single production process pp→t^~1X(~)1→tX^~1⁰X^~1^-,the top quark has two decay channels:leptonic channel and hadronic channel.In this paper,we probe the observability of these two channels in a simplified minimal supersymmetric standard model scenario.We find that,at the 27 TeV LHC with the integrated luminosity of L=15 ab^-1,mt^-1<1900 GeV andμ<750 GeV can be excluded at 2σthrough the leptonic mono-top channel,while m_t^-1<1200 GeV andμ<350 GeV can be excluded at 2σthrough the hadronic channel.     

Using Pantheon and Hubble parameter data to constrain the Ricci dark energy in a Bianchi I Universe

In this work, we use the most recent publicly available type Ia supernova (SNIa) compilations and H(z) data. A well formulated cosmological model based on Bianchi type I (BI) metric is implemented in the presence of the Ricci dark energy model. Using the maximum likelihood technique, we estimate the present value of Hubble's constant H₀ = 70.339 ± 0.743, matter density parameter ${{\rm{\Omega }}}_{{m}_{0}}=0.297\pm 0.031$, anisotropy parameter ${{\rm{\Omega }}}_{{\sigma }_{0}}=\,$−0.004 01 ± 0.001 07 within $1\sigma ^{\prime} $ confidence level by bounding our derived model with recent joint Pantheon and H(z) data. We have constrained the present value of the equation of state parameter as ω_de = −1.17 joint with the observational data. The present value of the deceleration parameter of the Universe in the derived model is obtained as ${q}_{0}=-{0.749}_{-0.086}^{+0.076}$. Transition redshift is also derived as ${z}_{\mathrm{tr}}\sim 0.551$ with the recent observations (Pantheon + H(z)) datasets. Finally, we compare the anisotropy effects on the evolution of H(z) for the proposed model under consideration with different observational datasets.     

Preferential attachment network model with aging and initial attractiveness

In this paper, we generalize the growing network model with preferential attachment for new links to simultaneously include aging and initial attractiveness of nodes. The network evolves with the addition of a new node per unit time, and each new node has m new links that with probability Π_i are connected to nodes i already present in the network. In our model, the preferential attachment probability Π_i is proportional not only to k_i + A, the sum of the old node i's degree k_i and its initial attractiveness A, but also to the aging factor ${\tau }_{i}^{-\alpha }$, where τ_i is the age of the old node i. That is, ${{\rm{\Pi }}}_{i}\propto ({k}_{i}+A){\tau }_{i}^{-\alpha }$. Based on the continuum approximation, we present a mean-field analysis that predicts the degree dynamics of the network structure. We show that depending on the aging parameter α two different network topologies can emerge. For α < 1, the network exhibits scaling behavior with a power-law degree distribution P(k) ∝ k^−γ for large k where the scaling exponent γ increases with the aging parameter α and is linearly correlated with the ratio A/m. Moreover, the average degree k(t_i, t) at time t for any node i that is added into the network at time t_i scales as $k({t}_{i},t)\propto {t}_{i}^{-\beta }$ where 1/β is a linear function of A/m. For α > 1, such scaling behavior disappears and the degree distribution is exponential.     

P-v criticality and heat engine efficiency for Bardeen Einstein-Gauss-Bonnet AdS black hole

In this paper,we discuss the P-v criticality and the heat engine efficiency in the Bardeen EinsteinGauss-Bonnet (EGB) AdS black hole space-time.From the P-v plane in the extended phase space,we find that the Bardeen EGB-AdS black hole conforms to Van der Waals (VdW) liquid-gas systems in the extended phase space,and P_cv_/T_c=0.369 of the Bardeen EGB-AdS black hole system is between 0.3333 of the Gauss-Bonnet AdS black hole system and 0.375 of the VdW gas system in the 5-dimensions.Then we construct a heat engine by taking the Bardeen EGB-AdS black hole as the working substance,and consider a rectangle heat cycle in the P-v plane.We find that two cases with different Bardeen parameter e and Gauss-Bonnet parameter a both have the same situation,i.e.as the entropy difference between small black hole and large black hole S2 increases,the heat engine efficiency will increase.Furthermore,as the Bardeen parameter e increases,the efficiency will decrease.However,for the Gauss-Bonnet parameter a,the result is contrary.By comparing with the well-know Carnot heat engine efficiency,we have found the efficiency ratioη/η_c versus entropy S_2 is bounded below l,so it is coincided with the thermodynamical second law.     

Study of semileptonic decay of ${\bar{B}}_{s}^{0} \rightarrow \phi {l}^{+}{l}^{-}$ in QCD sum rule

In this work we study the semileptonic decay of ${\bar{B}}_{s}^{0}\to \phi {l}^{+}{l}^{-}$ (l=e, μ, τ) with the QCD sum rule method. We calculate the ${\bar{B}}_{s}^{0}\to \phi $ translation form factors relevant to this semileptonic decay, then the branching ratios of ${\bar{B}}_{s}^{0}\to \phi {l}^{+}{l}^{-}$ (l=e, μ, τ) decays are calculated with the form factors obtained here. Our result for the branching ratio of ${\bar{B}}_{s}^{0}\to \phi {\mu }^{+}{\mu }^{-}$ agree very well with the recent experimental data. For the unmeasured decay modes such as ${\bar{B}}_{s}^{0}\to \phi {e}^{+}{e}^{-}$ and ${\bar{B}}_{s}^{0}\to \phi {\tau }^{+}{\tau }^{-}$, we give theoretical predictions.     

Quantum uncertainty relations of Tsallis relative α entropy coherence based on MUBs

In this paper,we discuss quantum uncertainty relations of Tsallis relative α entropy coherence for a single qubit system based on three mutually unbiased bases.For α∈[1/2,1)U(1,2],the upper and lower bounds of sums of coherence are obtained.However,the above results cannot be verified directly for any α∈(0,1/2).Hence,we only consider the special case of α=1/n+1,where n is a positive integer,and we obtain the upper and lower bounds.By comparing the upper and lower bounds,we find that the upper bound is equal to the lower bound for the special α=1/2,and the differences between the upper and the lower bounds will increase as α increases.Furthermore,we discuss the tendency of the sum of coherence,and find that it has the same tendency with respect to the different θ or φ,which is opposite to the uncertainty relations based on the Rényi entropy and Tsallis entropy.     

Scalar one-loop four-point integral with one massless vertex in loop regularization

The scalar one-loop four-point function with one massless vertex is evaluated analytically by employing the loop regularization method. According to the method, a characteristic scale μ_s is introduced to regularize the divergent integrals. The infrared divergent parts, which take the form of ln~2(λ~2/μ_s~2)and ln(λ~2/μ_s~2)as μ_s→ 0 where λ is a constant and expressed in terms of masses and Mandelstam variables, and the infrared stable parts are well separated. The result is shown explicitly via 44 dilogarithms in the kinematic sector in which our evaluation is valid.     

Eigen microstates and their evolutions in complex systems

Emergence refers to the existence or formation of collective behaviors in complex systems. Here,we develop a theoretical framework based on the eigen microstate theory to analyze the emerging phenomena and dynamic evolution of complex system. In this framework, the statistical ensemble composed of M microstates of a complex system with N agents is defined by the normalized N × M matrix A, whose columns represent microstates and order of row is consist with the time. The ensemble matrix A can be decomposed as ■, where r= min(N,M), eigenvalue σIbehaves as the probability amplitude of the eigen microstate U_I so that ■ and U_I evolves following V_I. In a disorder complex system, there is no dominant eigenvalue and eigen microstate. When a probability amplitude σIbecomes finite in the thermodynamic limit, there is a condensation of the eigen microstate UIin analogy to the Bose–Einstein condensation of Bose gases. This indicates the emergence of U_I and a phase transition in complex system. Our framework has been applied successfully to equilibrium threedimensional Ising model, climate system and stock markets. We anticipate that our eigen microstate method can be used to study non-equilibrium complex systems with unknown orderparameters, such as phase transitions of collective motion and tipping points in climate systems and ecosystems.     

Study of the XYZ states at the BESIII

With its unique data samples at energies of 3.8–4.6 GeV, the BESIII experiment made a significant contribution to the study of charmonium and charmonium-like states, i.e., the XYZ states.We review the results for observations of the Z_c(3900) and Z_c(4020) states, the X(3872) in e⁺e⁻ annihilation, and charmonium ψ(1³D₂) state, as well as measurements of the cross-sections of ωχ_cJ and ηJ/ψ, and the search for e⁺e⁻→ γχ_cJ and γY (4140). We also present data from BESIII that may further strengthen the study of the XYZ and conventional charmonium states, and discuss perspectives on future experiments.     

Systematic study of α decay half-lives for even–even nuclei within a deformed two-potential approach

In this work, we systematically study the α decay half-lives of 196 even–even nuclei using a two-potential approach improved by considering nuclear deformation. The results show that the accuracy of this model has been improved after considering nuclear deformation. In addition, we extend this model to predict the α decay half-lives of Z = 118 and 120 isotopes by inputting the α decay energies extracted from the Weizsacker–Skyrme-type (WS-type) mass model, a simple nuclear mass formula, relativistic continuum Hartree–Bogoliubov theory and Duflo-Zuker-19 (DZ19) mass model. It is useful for identifying the new superheavy elements or isotopes for future experiments. Finally, the predicted α decay energies and half-lives of Z = 118 and 120 isotopes are analyzed, and the shell structure of superheavy nuclei is discussed. It shows that the shell effect is obvious at N = 184, while the shell effect at N = 178 depends on the nuclear mass model.     

The upper bound on the tensor-to-scalar ratio consistent with quantum gravity

We consider the polynomial inflation with the tensor-to-scalar ratio as large as possible which can be consistent with the quantum gravity(QG) corrections and effective field theory(EFT). To get a minimal field excursion Δ? for enough e-folding number N, the inflaton field traverses an extremely flat part of the scalar potential, which results in the Lyth bound to be violated. We get a CMB signal consistent with Planck data by numerically computing the equation of motion for inflaton ? and using Mukhanov–Sasaki formalism for primordial spectrum. Inflation ends at Hubble slow-roll parameter ■. Interestingly, we find an excellent practical bound on the inflaton excursion in the format ■, where a is a tiny real number and b is at the order 1. To be consistent with QG/EFT and suppress the high-dimensional operators, we show that the concrete condition on inflaton excursion is ■. For n_s= 0.9649,N_e= 55, and ■0.632 MPl, we predict that the tensor-to-scalar ratio is smaller than 0.0012 for such polynomial inflation to be consistent with QG/EFT.     

Probing vector-like top partner from same-sign dilepton events at the LHC

The standard model is a successful theory but is lacking a mechanism for neutrino mass generation as well as a solution to the naturalness problem. In the models that are proposed to simultaneously solve the two problems, heavy Majorana neutrinos and top partners are usually predicted to lead to a new decay mode of the top partner mediated by the heavy Majorana neutrinos: $T\to b\,{W}^{+}\to b\,{{\ell }}^{+}{{\ell }}^{+}q\bar{q^{\prime} }$. In this paper, we will study the observability of such a new signature via the pair production process of a top partner ${pp}\to T\bar{T}\to 2b+{{\ell }}^{\pm }{{\ell }}^{\pm }+4j$ in a model independent way. By performing Monte Carlo simulations, we present the 2σ exclusion limits of the top partner mass and mixing parameters at the HL-LHC.     

Constraint on nuclear symmetry energy imposed by f-mode oscillation of neutron stars

Due to improvements in the sensitivity of gravitational wave (GW) detectors, the detection of GWs originating from the fundamental quasi-normal mode (f-mode) of neutron stars has become possible. The future detection of GWs originating from the f-mode of neutron stars will provide a potential way to improve our understanding of the nature of nuclear matter inside neutron stars. In this work, we investigate the constraint imposed by the f-mode oscillation of neutron stars on the symmetry energy of nuclear matter using Bayesian analysis and parametric EOS. It is shown that if the frequency of the f-mode of a neutron star of known mass is observed precisely, the symmetry energy at twice the saturation density (E_sym(2ρ₀)) of nuclear matter can be constrained within a relatively narrow range. For example, when all the following parameters are within the given intervals: 220 ≤ K₀ ≤ 260 MeV, 28 ≤ E_sym(ρ₀) ≤ 36 MeV, 30 ≤ L ≤ 90 MeV, −800 ≤ J₀ ≤ 400 MeV, − 400 ≤ K_sym ≤ 100 MeV, −200 ≤ J_sym ≤ 800 MeV, E_sym(2ρ₀) will be constrained to within ${48.8}_{-5.5}^{+6.6}$ MeV if the f-mode frequency of a canonical neutron star (1.4 M_⊙) is observed to be 1.720 kHz with a 1% relative error. Furthermore, if only f-mode frequency detection is available, i.e. there is no stellar mass measurement, a precisely detected f-mode frequency can also impose an accurate constraint on the symmetry energy. For example, given the same parameter space and the same assumed observed f-mode frequency mentioned above, and assuming that the stellar mass is in the range of 1.2–2.0 M_⊙, E_sym(2ρ₀) will be constrained to within ${49.5}_{-6.8}^{+8.1}\,\mathrm{MeV}$. In addition, it is shown that a higher slope of 69 ≤ L ≤ 143 MeV will give a higher posterior distribution of E_sym(2ρ₀), ${53.8}_{-6.4}^{+7.0}\,\mathrm{MeV}$.     

Hiding neutrinoless double beta decay in the minimal seesaw model with the TM1 or μ–τ reflection symmetry

In Asaka et al (2021 Phys. Rev. D 103, 015014), Asaka, Ishida and Tanaka put forward an interesting possibility that the neutrinoless double beta decay can be hidden in the minimal seesaw model with the two right-handed neutrinos having a hierarchical mass structure: the lighter one is lighter enough than the typical Fermi-momentum scale of nuclei while the heavier one is sufficiently heavy to decouple from the neutrinoless double beta decay. Then, in the basis where the mass matrices of the charged leptons and right-handed neutrinos are diagonal, for some particular texture of the Dirac neutrino mass matrix ${M}_{{\rm{D}}}^{}$, the neutrinoless double beta decay can be hidden. In this paper, on top of this specified model, we study the interesting scenario that ${M}_{{\rm{D}}}^{}$ further obeys the TM1 symmetry or μ–τ reflection symmetry which are well motivated by the experimental results for the neutrino mixing parameters.     

On the Riemann–Hilbert problem of a generalized derivative nonlinear Schrödinger equation

In this work,we present a unified transformation method directly by using the inverse scattering method for a generalized derivative nonlinear Schr?dinger(DNLS)equation.By establishing a matrix Riemann-Hilbert problem and reconstructing potential function q(x,t)from eigenfunctions{Gj(x,t,η)}3/1 in the inverse problem,the initial-boundary value problems for the generalized DNLS equation on the half-line are discussed.Moreover,we also obtain that the spectral functions f(η),s(η),F(η),S(η)are not independent of each other,but meet an important global relation.As applications,the generalized DNLS equation can be reduced to the Kaup-Newell equation and Chen-Lee-Liu equation on the half-line.