Search

We derive and analyze the confinement potential of the Cornell type within the framework of the generalized soft wall holographic model that includes a parameter controlling the intercept of the linear Regge spectrum. In the phenomenology of Regge trajectories, this parameter is very important for the quantitative description of experimental data. Our analysis shows that the ‘linear plus Coulomb’ confinement potential obtained in the scalar channel is quantitatively consistent with the phenomenology and lattice simulations while the agreement in the vector channel is qualitative only. This result indicates the key role of the vacuum scalar sector in the formation of the confinement potential. As a by-product the overall consistency of our holographic description of confinement potential seems to confirm the glueball nature of the scalar meson f 0(1500). [ABSTRACT FROM AUTHOR]

In heavy-to-light B decays, the heavy-quark/large-energy symmetry reduces the number of QCD form factors. At large final state meson energy, these form factors receive sizeable perturbative corrections. The hard-gluon vertex corrections are absorbed in the coefficients of soft-form factors, while the hard-spectator interactions generate symmetry-breaking corrections and end-point singularities. At an order of 1/ m b, using the heavy-quark/large-energy symmetry, the end-point singularities can also be absorbed in the soft form factors, whereas the symmetry breaking corrections add separately to the form factors. In this work, we calculate these perturbative corrections for B â†' TÎĽ + ÎĽ âˆ' decays, with T representing the tensor mesons K 2 * , f 2 , a 2 all having J P = 2+. We find that the values of the branching ratio (Br) and the zero-position of the forwardâ€"backward asymmetry ( A F B ) of B â†' K 2 * ÎĽ + ÎĽ âˆ' decay receive nearly 5% and 14% contributions, respectively, from these radiative corrections. Compared to these observables, the radiative corrections change the averaged longitudinal lepton polarization asymmetry (⟨ P Lâź©) by 13%. Therefore, prior to attributing any deviation from the SM predictions of these asymmetries as a hint of NP, one has to take into account the contributions of vertex and hard-spectator corrections. [ABSTRACT FROM AUTHOR]

The three pentaquark states, P c (4312) , P c (4440) and P c (4457) , discovered by the LHCb Collaboration in 2019, can be arranged into a complete heavy quark spin symmetry multiplet of hadronic molecules of D ¯ (∗) Σ c (∗) . In the heavy quark mass limit, the Σ c (∗) baryons can be related to the doubly charmed tetraquark states of isospin 1, i.e., T c ¯ c ¯ (∗) ( T c ¯ c ¯ 0 , T c ¯ c ¯ 1 , T c ¯ c ¯ 2 ), via heavy antiquark diquark symmetry, which dictates that the D ¯ (∗) Σ c (∗) interactions are the same as the D ¯ (∗) T c ¯ c ¯ (∗) interactions up to heavy antiquark diquark symmetry breakings. In this work, we employ the contact-range effective field theory to systematically study the D ¯ (∗) T c ¯ c ¯ (∗) systems, and we show the existence of a complete heavy quark spin symmetry multiplet of hadronic molecules composed of a doubly charmed tetraquark state and a charmed meson. These are a new kind of hadronic molecules and, if discovered, can lead to a better understanding of the many exotic hadrons discovered so far. In addition, we summarise the triply charmed hexaquark states formed by different combinations of hadrons. In particular, we show that Ω ¯ ccc p system can bind by the Coulomb force, which is analogous to a hydrogenlike atom. [ABSTRACT FROM AUTHOR]

Using a symmetry-preserving regularisation of a vector × vector contact interaction (SCI), we complete a systematic treatment of twelve semileptonic transitions with vector meson final states: D → ρ , D (s) → K ∗ , D s → ϕ , B → ρ , B s → K ∗ , B (s) → D (s) ∗ , B c → B (s) ∗ , J / ψ , D ∗ ; and thereby finalise a unified analysis of semileptonic decays of heavy + heavy and heavy + light pseudoscalar mesons to both pseudoscalar and vector meson final states. The analysis is marked by algebraic simplicity, few parameters, and the ability to consistently describe systems from Nambu-Goldstone modes to heavy + heavy mesons. Regarding the behaviour of the transition form factors, the SCI results compare well wherever sound experimental or independent theory analyses are available; hence, the SCI branching fraction predictions should be a reasonable guide. Considering the ratios R (D (s) (∗)) , R (J / ψ) , R (η c) , whose values are key tests of lepton universality in weak interactions, the SCI values agree with Standard Model predictions. The B (s) → D (s) ∗ transitions are used to predict the precursor functions that evolve into the universal Isgur–Wise function in the heavy-quark limit, with results that conform with those from other sources where such are available. The study also exposes effects on the transition form factors that flow from interference between emergent hadron mass from the strong interaction and Higgs boson couplings via current-quark masses, including flavour symmetry violation. [ABSTRACT FROM AUTHOR]

We evaluate theoretically the interaction of the open bottom and strange systems B ¯ K ¯ , B ¯ ∗ K ¯ , B ¯ K ¯ ∗ and B ¯ ∗ K ¯ ∗ to look for possible bound states which could correspond to exotic non-quark–antiquark mesons since they would contain at least one b and one s quarks. The s-wave scattering matrix is evaluated implementing unitarity by means of the Bethe–Salpeter equation, with the potential kernels obtained from contact and vector meson exchange mechanisms. The vertices needed are supplied from Lagrangians derived from suitable extensions of the hidden gauge symmetry approach to the bottom sector. We find poles below the respective thresholds for isospin 0 interaction and evaluate the widths of the different obtained states by including the main sources of imaginary part, which are the B ∗ → B γ decay in the B ¯ ∗ K ¯ channels, the K ∗ → K π in the channels involving a K ∗ , plus the box diagrams with B ¯ K ¯ and B ¯ ∗ K ¯ intermediate states for the B ¯ ∗ K ¯ ∗ channels. [ABSTRACT FROM AUTHOR]

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We discuss spontaneous chiral symmetry breaking and the quark bilinear condensate in large- Nc quantum chromodynamics (QCD). It is known that the existence of the η′ meson is implied in large- Nc QCD, as pointed out by Witten[ 27 ] and Veneziano[ 28 ]. First, we show that the existence of η′ and the Ward–Takahashi identities implies the existence of Nambu–Goldstone bosons from chiral symmetry breaking SU (Nf) L × SU (Nf) R → SU (Nf) V . Second, we show that a QCD inequality implies a non-zero lower bound on the quark bilinear condensate. [ABSTRACT FROM AUTHOR]

Abstract Background Large-scale fusion reactors using hydrogen isotopes as fuel are under development at several places in the world. These types of fusion reactors use tritium as fuel for the T + D reaction. However, tritium is not a sustainable fuel, since it likely will require fission reactors for its production, and since it is a dangerous material due to its radioactivity with main risks of release to the environment during tritium production, transport and refuelling operations. Thus, widespread use of fusion relying on tritium fuel should be avoided. At least two better methods for producing the nuclear energy needed in the world indeed already exist, using deuterium or ordinary hydrogen as fuel, and more methods need to be developed. It should be noted that the first experiments with sustained laser-driven fusion above break-even using deuterium as fuel were published already in 2015. Similar results for T + D fusion do not exist even after 60 years of development, which gives no confidence in this approach. Main text The well-known muon-induced fusion (often called muon-catalyzed fusion) can use non-radioactive deuterium as fuel. With the recent development of a high intensity muon source (1013 muons per laser shot) (patented), this method is technically and economically feasible today. Due to the low energy cost of producing muons at

Inner-shell ionization has many applications related to material analysis. However, full theoretical calculations in heavy multielectronic atoms are scarce. In this contribution, we assess proton and electron impact L i and M i -subshell ionization cross-sections of heavy targets (72 ≤ Z ≤ 83) using two theoretical models. These calculations are based on the Distorted Plane Wave Born Approximation for electron impact and the shellwise local plasma approximation for the proton impact, combined with relativistic calculations of these deep subshells wave functions and binding energies. We analyze the L-shell ionization of W, Au, and Bi and the M-shell of Hf, Ta, W, Re, Os, Pt, Au, Pb, and Bi. Present values are compared with available experimental data from the literature, with disparate agreement. The convergence of proton and electron impact cross-sections at high-impact velocities is also discussed. [ABSTRACT FROM AUTHOR]

A reaction model for γ + p → J / ψ + p photoproduction, which exposes the c c ¯ content of the photon in making the transition γ → c c ¯ + P → J / ψ and couples the intermediate c c ¯ system to the proton's valence quarks via Pomeron (P) exchange, is used to deliver a description of available data, viz. both differential and total cross sections from near threshold, where data has newly been acquired, to invariant mass W ≈ 300 GeV. The study suggests that it is premature to link existing γ + p → J / ψ + p data with, for instance, in-proton gluon distributions, the quantum chromodynamics trace anomaly, or pentaquark production. Further developments in reaction theory and higher precision data are necessary before the validity of any such connections can be assessed. [ABSTRACT FROM AUTHOR]

In this brief note, we confront our results on diffractive photoproduction of J / ψ mesons with the putative gluon shadowing ratio defined as R g = σ (γ A → J / ψ A) / σ IA. , where σ IA is the result in impulse approximation. Building on our earlier description of the process in the color-dipole approach, where we took into account the rescattering of c c ¯ states only, we demonstrate that the inclusion of c c ¯ g -Fock states improves the description at small x commonly associated with gluon shadowing. [ABSTRACT FROM AUTHOR]

The mass and width of the tensor tetraquark T = b b c ‾ c ‾ with spin-parity J P = 2 + are calculated in the context of the QCD sum rule method. The tetraquark T is modeled as a diquark-antidiquark state built of components b T C γ μ b and c ‾ γ ν C c ‾ T with C being the charge conjugation matrix. The mass m = (12.795 ± 0.095) GeV of the exotic tensor meson T is found by means of the two-point sum rule approach. Its full width Γ is evaluated by considering processes T → B c − B c − , B c − B c ⁎ − , and B c ⁎ − B c ⁎ −. Partial widths of these decays are computed by means of the three-point sum rule approach which is used to determine the strong couplings at relevant tetraquark-meson-meson vertices. Predictions obtained for the width Γ T = 55.5 − 9.9 + 10.6 MeV , as well as the mass of the tetraquark T can be useful in investigations of fully heavy four-quark mesons. [ABSTRACT FROM AUTHOR]

Microplastics are widely present in the natural environment and exhibit a strong affinity for heavy metals in water, resulting in the formation of microplastics composite heavy metal pollutants. This study investigated the adsorption of heavy metals by electron beam-aged microplastics. For the first time, electron beam irradiation was employed to degrade polypropylene, demonstrating its ability to rapidly age microplastics and generate a substantial number of oxygen-containing functional groups on aged microplastics surface. Adsorption experiments revealed that the maximum adsorption equilibrium capacity of hexavalent chromium by aged microplastics reached 9.3 mg g−1. The adsorption process followed second-order kinetic model and Freundlich model, indicating that the main processes of heavy metal adsorption by aged microplastics are chemical adsorption and multilayer adsorption. The adsorption of heavy metals on aged microplastics primarily relies on the electrostatic and chelation effects of oxygen-containing functional groups. The study results demonstrate that environmental factors, such as pH, salinity, coexisting metal ions, humic acid, and water matrix, exert inhibitory effects on the adsorption of heavy metals by microplastics. Theoretical calculations confirm that the aging process of microplastics primarily relies on hydroxyl radicals breaking carbon chains and forming oxygen-containing functional groups on the surface. The results indicate that electron beam irradiation can simultaneously oxidize and degrade microplastics while reducing hexavalent chromium levels by approximately 90%, proposing a novel method for treating microplastics composite pollutants. Gas chromatography-mass spectrometry analysis reveals that electron beam irradiation can oxidatively degrade microplastics into esters, alcohols, and other small molecules. This study proposes an innovative and efficient approach to treat both microplastics composite heavy metal pollutants while elucidating the impact of environmental factors on the adsorption of heavy metals by electron beam-aged microplastics. The aim is to provide a theoretical basis and guidance for controlling microplastics composite pollution. [Display omitted] • Electron beam irradiation can achieve effective aging of microplastics. • The physicochemical properties after electron beam irradiation were determined. • The adsorption process and mechanism of Cr(Ⅵ) on aging MPs were studied. • Study the impact of environmental factors on the adsorption of aged MPs. • The OCFGs of MPs are the main reason for the change of adsorption properties. [ABSTRACT FROM AUTHOR]

Based on analyses of the mass and the strong decay features, D s 0 (2590) + observed by LHCb collaboration is identified as a radial excitation of the pseudoscalar D s , and D s J (3040) + observed by BaBar collaboration is identified as a radial excitation of D s 1 (2536) ±. D s 0 (2590) + is possibly a pure D s (2 S 0 1) meson, both basic D s 1 (2536) ± and radially excited D s J (3040) + are possibly the mixtures D s (n P 1) between spin triplet D s (n P 1 3) and spin singlet D s (n P 1 1). In this arrangement, their masses meet the linear behavior of the radial Regge trajectory very well. In the P 0 3 strong decay model, the decay channels of D s 0 (2590) + are D ⁎ 0 K + and D ⁎ + K 0 , the total decay width is predicted with Γ = 76.12 MeV. The main decay channels of D s J (3040) + are D ⁎ 0 K + / D ⁎ + K 0 and D ⁎ 0 K ⁎ + / D ⁎ + K ⁎ 0 , the total decay width is predicted with Γ = 283.46 MeV. These numerical strong decay results are consistent with the experiment data and support our arrangement. The dimensionless strength creation parameter γ plays an important role in the calculation, and γ = 9.57 is fixed through a comparison of the predicted strong decay widths of D s 2 ⁎ (2573) and D s 3 ⁎ (2860) ± with experimental data. [ABSTRACT FROM AUTHOR]

We suppose that there exist three vector hidden-charm tetraquark states with the J P C = 1 − − at the energy about 4.5 GeV , and investigate the two-body strong decays systematically. We obtain thirty QCD sum rules for the hadronic coupling constants based on rigorous quark-hadron duality, then obtain the partial decay widths, therefore the total widths approximately, which are compatible with the experimental data of the Y (4500) from the BESIII collaboration. The Y (4500) may be one vector tetraquark state having three main Fock components, or consists of three different vector tetraquark states. We can search for the typical decays Y → D ¯ 1 0 D 0 − D ¯ 0 D 1 0 2 , D ¯ 1 − D + − D ¯ − D 1 + 2 , D ¯ 0 0 D ⁎ 0 − D ¯ ⁎ 0 D 0 0 2 , D ¯ 0 − D ⁎ + − D ¯ ⁎ − D 0 + 2 , η c ω , J / ψ ω to diagnose the nature of the Y (4500). [ABSTRACT FROM AUTHOR]

The global spin alignment of the vector meson has been observed in relativistic heavy ion collisions, but its theoretical origin is still on hot debates. Here we propose to apply the light front framework to explain this phenomenon since the light front form explicitly describes the hadron spin including both the quark spin and the orbital angular momentum. After applying the light front spinor, we find that the spin alignment in the polarization of vector mesons with ρ 00 > 1 / 3 can be naturally manifested and in particular, the obtained spin alignment for ϕ meson is in good agreement with the experimental data. This implies that to explain the spin alignment it is important to properly include the contribution from the gluon interactions that are presented in terms of the orbital angular momentum of the hadron bound state. [ABSTRACT FROM AUTHOR]

Using a symmetry-preserving truncation of the quantum field equations describing hadron properties, parameter-free predictions are delivered for pion and kaon elastic electromagnetic form factors, F P = π , K , thereby unifying them with kindred results for nucleon elastic electromagnetic form factors. Regarding positive-charge states, the analysis stresses that the presence of scaling violations in QCD entails that Q 2 F P (Q 2) should exhibit a single maximum on Q 2 > 0. Locating such a maximum is both necessary and sufficient to establish the existence of scaling violations. The study predicts that, for charged π , K mesons, the Q 2 F P (Q 2) maximum lies in the neighbourhood Q 2 ≃ 5 GeV2. Foreseeable experiments will test these predictions and, providing their Q 2 reach meets expectations, potentially also provide details on the momentum dependence of meson form factor scaling violation. [ABSTRACT FROM AUTHOR]

We present the light-quark mass dependence of the Λ (1405) resonance at leading order in a renormalizable framework of covariant chiral effective field theory. The meson-baryon scattering amplitudes, which are obtained by solving the scattering equation within time-ordered perturbation theory, follow the quark mass trajectory of the Coordinated Lattice Simulations consortium. At M π ≈ 200 MeV and M K ≈ 487 MeV, our parameter-free prediction of Λ (1405) poles is consistent with the recent lattice results of BaSc Collaboration [Phys. Rev. Lett. 132, 051901 (2024)]. Varying the pion mass from 135 MeV to 400 MeV, we present the evolution of double-pole positions of Λ (1405) : the higher pole remains a resonance around the K ¯ N threshold; whereas the lower pole undergoes a transition from resonance to a virtual state, and ultimately to a bound state of the π Σ system, which could be verified by the forthcoming lattice QCD simulations. [ABSTRACT FROM AUTHOR]

We report on the results of the first search for the production of axion-like particles (ALPs) via Primakoff production on nuclear targets, γ A → a A , in the "SRC-CT" experiment using the GlueX detector at Jefferson Lab. This search uses an integrated luminosity of 100 pb ⋅ − 1 nucleon on a 12C target with a real photon beam of energies 6 < E γ < 10.8 GeV, and explores the mass region of 200 < m a < 450 MeV via the decay a → γ γ. This mass range is between the π 0 and η meson masses, which enables the use of the measured η meson production rate to obtain absolute bounds on the ALP production with reduced sensitivity to experimental luminosity and detection efficiency. We find no evidence for an ALP, consistent with previous searches in the quoted mass range, and present limits on the effective photon coupling scale of O (1 TeV − 1). We further find that the ALP production limit we obtain is hindered by the peaking structure of the non-target-related dominant background the in GlueX spectrometer, which we treat by using data on 4He to estimate and subtract it. We comment on how this search can be improved in a future higher-statistics dedicated measurement. [ABSTRACT FROM AUTHOR]

In light of recent measurements suggesting potential lepton flavor universality violations in semileptonic decays at collider experiments, this article provides a concise study of tree- and loop-level B-hadron semileptonic decays, b→clνl\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$b \rightarrow c l \nu _l$$\end{document} and b→sl+l-\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$b \rightarrow s l^+ l^-$$\end{document}. We provide predictions for lepton flavor violating observables, RJ/ψ\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\mathcal {R}}_{J/\psi }$$\end{document} and Rηc\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\mathcal {R}}_{\eta _c}$$\end{document}, across the entire q2\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$q^2$$\end{document} range. Our study employs the Relativistic Independent Quark Model (RIQM), highlighting a model-dependent approach to these observables. We compare our model’s predictions with existing lattice predictions, demonstrating the strong applicability of the RIQM framework in describing Bc\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$B_c$$\end{document} decays. Additionally, we reassess global averages for RD(D∗)\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\mathcal {R}}_{D(D^*)}$$\end{document} and RK(K∗)\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\mathcal {R}}_{K(K^*)}$$\end{document} in semileptonic transitions. With the upcoming experimental upgrades and the anticipated Run 3 data on Bc\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$B_c$$\end{document} meson decays, rapid confirmation of these quantities could indicate significant evidence of physics beyond the Standard Model, thereby opening new pathways for understanding the complex flavor dynamics in B meson decays. [ABSTRACT FROM AUTHOR]

Masses and current couplings of the charmonium and bottomonium hybrids c ‾ g c and b ‾ g b with spin-parities J PC = 0 + + , 0 + − , 0 − + , 0 − − and 1 + + , 1 + − , 1 − + , 1 − − are calculated using QCD two-point sum rule method. Computations are performed by taking into account gluon condensates up to dimension 12 including terms ∼ 〈 g s 3 G 3 〉 2. The parameters of the bottom-charm hybrids b ‾ g c with quantum numbers J PC = 0 + , 0 − , 1 + , and 1 − are calculated as well. In computations the dominance of the pole contribution to sum rule results is ensured. It is demonstrated that all charmonia hybrids decay strongly to two-meson final states. The bottomonium hybrids 0 − + and 1 − + as well as the bottom-charm hybrid mesons 0 − (+) and 1 − (+) may be stable against strong two-meson decay modes. Results of the present work are compared with ones obtained using the sum rule and alternative approaches. Our predictions for parameters of the heavy hybrid mesons may be useful to study their various decay channels which are important for interpretation of ongoing and future experiments. [ABSTRACT FROM AUTHOR]

Recent measurements of C P -related comparisons of the weak-interaction parameters that describe the decays of the Ξ − and the Ξ ̄ + doubly strange hyperon and antihyperon are reviewed and their significance is discussed. [ABSTRACT FROM AUTHOR]

In this paper, we construct the diquark–diquark–diquark-type vector six-quark currents to investigate the vector and scalar hexaquark states in the framework of the QCD sum rules in a consistent way, and make predictions for the hexaquark masses. We can search for the fully heavy hexaquark states in the di- Ω c c c and di- Ω b b b invariant mass spectra in the future. Combined with our previous works on the fully heavy tetraquark states and pentaquark states, the present predictions can shed light on the nature of the fully heavy multiquark states. [ABSTRACT FROM AUTHOR]

The masses of open bottom mesons (B ( B + , B 0 ), B ̄ ( B − , B 0 ̄), B s ( B s 0 , B s 0 ̄)) and upsilon states (Υ (1 S) , Υ (2 S) , Υ (3 S) , Υ (4 S) and Υ (1 D)) are investigated in the isospin asymmetric strange hadronic medium at finite temperature in the presence of strong magnetic fields using a chiral effective Lagrangian approach. Here the chiral SU(3) Lagrangian is generalized to include the bottom sector to incorporate the interactions of the open bottom mesons with the magnetized medium. At finite temperature, the number density and scalar density of baryons are expressed in terms of thermal distribution functions. For charged baryons, the magnetic field introduces contribution from Landau energy levels. The masses of the open bottom mesons get modified through their interactions with the baryons and the scalar mesons, which undergo modifications in a magnetized medium. The charged B + , B − mesons have additional positive mass shifts due to Landau quantization in the presence of the magnetic field. The medium mass shift of the upsilon states originates from the modification of the gluon condensates simulated by the variation of dilaton field (χ) and a quark mass term in the magnetized medium. The open bottom mesons and upsilon states experience a mass drop in the magnetized medium. The masses of these mesons initially increase with a rise in temperature, and beyond a high value of temperature, their masses are observed to drop. When the temperature is below 90 MeV, the in-medium masses of the mesons increase with an increase in the magnetic field. However, at high temperatures (T > 90 MeV), the masses are observed to drop with an increase in the magnetic field. These in-medium modifications can have observable effects in asymmetric heavy-ion collisions experiments. [ABSTRACT FROM AUTHOR]

Advances in the exploration of the spectrum and structure of the excited states of the nucleon from experiments with electromagnetic probes on proton targets are presented. Impressive progress has been achieved in the studies of exclusive meson photoproduction in experiments with continuous electron beams and with detectors of almost 4 π acceptance. The high-quality data, coupled with the advances in the amplitude analyses of exclusive photo- and hadroproduction data, allow for the observation of several long-awaited new baryon states known previously as the "missing" resonances. Studies of exclusive meson electroproduction in the resonance region with the CLAS detector at JLab have provided the dominant part of the available world information on exclusive meson electroproduction observables. These data offer unique information on the structure of most well-established excited nucleon states in the mass region up to 1.8 GeV in terms of the evolution of their electroexcitation amplitudes with momentum transfer of the virtual photon. We discuss the impact of these results on the insight into the strong interaction dynamics that underlie the generation of the full spectrum of nucleon resonances of distinctively different structure. These results shed light on the emergence of hadron mass, which is one of the most important and still open problems in the Standard Model. The extension of the nucleon resonance studies in the experiments of the 12-GeV era at JLab with the CLAS12 detector are outlined. [ABSTRACT FROM AUTHOR]

For the two-body Bc → BM decays, where Bc denotes the anti-triplet charm baryon and B(M) the octet baryon (meson), there exist two theoretical studies based on the SU(3) flavor [SU(3)f] symmetry. One is the irreducible SU(3)f approach (IRA). In the irreducible SU(3)f representation, the effective Hamiltonian related to the initial and final states forms the amplitudes for Bc → BM. The other is the topological-diagram approach (TDA), where the W-boson emission and W-boson exchange topologies are drawn and parameterized for the decays. As required by the group theoretical consideration, we present the same number of the IRA and TDA amplitudes. We can hence relate the two kinds of the amplitudes, and demonstrate the equivalence of the two SU(3)f approaches. We find a specific W-boson exchange topology only contributing to Ξ c 0 →BM. Denoted by EM, it plays a key role in explaining B ( Ξ c 0 → Λ0 K S 0 , Σ0 K S 0 , Σ+K−). We consider that Λ c + → nπ+ and Λ c + → pπ0 proceed through the constructive and destructive interfering effects, respectively, which leads to B ( Λ c + → nπ+) » B ( Λ c + → pπ0) in agreement with the data. With the exact and broken SU(3)f symmetries, we predict the branching fractions of Bc→BM to be tested by future measurements. [ABSTRACT FROM AUTHOR]

The helicity amplitudes of the N(1520) and N(1535) resonances in the γ ∗ p → N ∗ electromagnetic transition are studied in the constituent quark model using the impulse approximation, with the proton and resonances assumed to be in three-quark configurations. The comparison of theoretical results and experimental data on the helicity amplitudes A 1 / 2 , A 3 / 2 , and S 1 / 2 indicates that the N(1520) and N(1535) resonances are primarily composed of three-quark L = 1 states but may contain additional components. However, it is improbable that contributions from meson clouds will be dominant at low Q 2 . [ABSTRACT FROM AUTHOR]

Using the MAMI-C microtron at an accelerator facility in Mainz, Germany, fixed target experiments carry on to study the excitation spectrum of the nucleon via the photoproduction of mesons. In this paper, the photon-induced production of the π0π+/- -pairs with a liquid deuterium target has been investigated in view of the helicity dependence of the two isospin channels. While unpolarized cross-sections for protons and neutrons have been extracted, this data alone is not sufficient to separate the resonances, therefore polarization observables are vital factors essential in disentangling the contributing resonant and non-resonant amplitudes. The double-polarization observable E was extracted with the help of a longitudinally polarized deuterated butanol target and a circularly polarized photon beam. The antiparallel and parallel spin configurations between the beam photon and the target nucleon imply the spin-dependent cross-sections σ1/2 and σ3/2, respectively, which have been derived from E. Reaction products were detected with an almost 4π solid-angle covering calorimeter composed of the Crystal Ball, TAPS detectors, and particle identification detectors. The results are sensitive to sequential decays of nucleon resonances that include intermediate states and also involve the emission of charged ρ mesons. Furthermore, comparative studies of the results of the most recent available model calculations were made. [ABSTRACT FROM AUTHOR]

In this work, we systematically investigate the dibaryons with charm number C = 1 and strangeness number S = ± 1 from the interactions of a charmed baryon and a strange baryon Λ c Λ , Λ c Σ (∗) , Σ c (∗) Λ , and Σ c (∗) Σ (∗) , and corresponding interactions of a charmed baryon and an antistrange baryon Λ c Λ ¯ , Λ c Σ ¯ (∗) , Σ c (∗) Λ ¯ , and Σ c (∗) Σ ¯ (∗) . With the help of the effective Lagrangians with SU(3), heavy quark, and chiral symmetries, the potentials of the interactions considered are constructed by light meson exchanges. To search for the possible molecules, the quasipotential Bethe–Salpeter equation with the interaction potential kernel is solved to find poles from scattering amplitude. The results suggest that attractions widely exist in charmed-strange system with C = 1 and S = - 1 . The S-wave bound states can be produced from most of the channels. Few bound states are also produced from the charmed-antistrange interactions. Couple-channel effect are considered in the current work to discuss the couplings of the molecular states to the channels considered. More experimental research for these charmed-strange dibaryons are suggested. [ABSTRACT FROM AUTHOR]

We describe the propagation of charm quarks in the quark-gluon plasma (QGP) by means of an event-by-event transport approach. In our calculations the non-perturbative interaction between heavy quarks and light partons has been taken into account through a quasi-particle approach with thermal light quark masses tuned to reproduce lQCD thermodynamics. We found that the flow observables v 2 and v 3 of D mesons are comparable with the experimental measurements for Pb + Pb collisions at 5.02 TeV in different ranges of centrality selections. The results are analyzed with event-shape engineering technique. The comparison of the anisotropic flow coefficients v n with experimental data show a quite good agreement with experimental data for different flow vector q 2 selections, which confirms the strong coupling between charm quarks and light quarks in the QCD matter. Furthermore, we present here a novel study of the event-by-event correlations between flow harmonics of D mesons and soft hadrons at LHC energy with the event-shape engineering technique that can put further constraints on heavy quark transport coefficients toward a solid comparison between the phenomenological determination and the lattice QCD calculations. [ABSTRACT FROM AUTHOR]

The D-meson production is investigated by considering the unintegrated gluon distribution within the dipole approach in the momentum representation. We analyze the D-meson spectrum accounting for the effects of nonlinear behavior of the QCD dynamics which can be accordingly addressed in the dipole framework. The unintegrated gluon distribution is obtained by using geometric scaling property and the results are compared to the Glauber–Gribov framework. The absolute transverse momentum spectra and the nuclear modification ratios are investigated. Predictions are compared with the experimental measurements by the ALICE and LHCb Collaborations in pA collisions for different rapidity bins. [ABSTRACT FROM AUTHOR]

Inspired by the lower statistical information in the bottom sector, in this paper, we calculate the masses and the strong decays of excited B and B s mesons in the framework of heavy quark effective theory (HQET). Using an effective chiral Lagrangian approach based on heavy quark spin-flavor and light quark chiral symmetry, we explore the flavor independent parameters Δ F (c) = Δ F (b) and λ F (c) = λ F (b) to calculate the masses of experimentally unknown bottom mesons. Our predictions are consistent with the available experimental results and other theoretical studies. Their strong decay to the ground state bottom mesons plus light pseudoscalar mesons is calculated in terms of the square of the couplings g H , g S , g T , g X , g Y , and g R . The weighted average value of the couplings g H , g S and g T is obtained in the charm sector (Phys. Rev. D 86: 054024, 2012) by fitting the calculated decay widths with experimental measurements, which will be used in the present study to analyze the strong decays of excited open bottom mesons. Moreover, the ratio of the decay rates is also predicted, which can be countered with future experimental data. [ABSTRACT FROM AUTHOR]

We study the process γ γ → π 0 π 0 involving the principal mechanisms, the structure of its cross section and the role of individual isoscalar-tensor resonances in the saturation of its energy spectrum. [ABSTRACT FROM AUTHOR]

We study F -wave bottom mesons in heavy quark effective theory. The available experimental and theoretical data is used to calculate the masses of F -wave bottom mesons. The decay widths of bottom mesons are analyzed to find upper bounds for the associated couplings. We also construct Regge trajectories for our predicted data in the (J, M 2) plane, and our results nicely fit on Regge lines. Our results may provide crucial information for future experimental studies. [ABSTRACT FROM AUTHOR]

The D-term is one of the conserved charges of hadrons defined as the forward limit of the gravitational form factor D (t). We calculate the nucleon's D-term in a holographic quantum chromodynamics model in which the nucleon is described as a soliton in five dimensions. We show that the form factor D (t) is saturated by the exchanges of infinitely many 0++ and 2++ glueballs dual to transverse-traceless metric fluctuations on the Wick-rotated AdS7 black hole geometry. We refer to this phenomenon as "glueball dominance," in perfect analogy to the vector meson dominance of the electromagnetic form factors. However, the value at vanishing momentum transfer D (t = 0) can be interpreted as due to the exchange of pairs of pions and infinitely many vector and axial-vector mesons without any reference to glueballs. We find that the D-term is slightly negative as a result of a cancellation between the isovector and isoscalar meson contributions. [ABSTRACT FROM AUTHOR]

In this paper, we calculate the ρ -meson timelike electromagnetic form factors by employing the k T factorization approach. The theoretical ratio for the moduli of three helicity amplitudes and total cross-section for the annihilation/production process e + e − → ρ + ρ − are analyzed at s = 1 0. 5 8 GeV , where the BaBar experiment was done. The results for the moduli of the three helicity amplitudes F i (Q 2) (i = L L , L T ∕ T L , T L) are predicted between 6 0 GeV 2 and 1 4 0 GeV 2 , and the three form factors G i (Q 2) (i = 1 , 2 , 3) of rho meson are considered. [ABSTRACT FROM AUTHOR]

The temperature behavior of the pion width in the hadronic phase is investigated in the framework of the Nambu–Jona–Lasinio (NJL) model. The contribution to the width from the pion–pion collision is considered with a scalar sigma-meson as an intermediate state. It is shown that the pion width significantly broadens at T > 0. 1 GeV. Using the two-step iteration method, suggested by Kadanoff and Baym, the pion spectral function in a hot pion gas is calculated at different temperatures. [ABSTRACT FROM AUTHOR]

In the framework of a multi-source thermal model at the partonic level, we have analyzed transverse momentum spectra of hadrons measured by the ALICE Collaboration in proton–proton ( p p or p–p) collisions at the center-of-mass energy of s = 7 and 13 TeV, proton–lead (p–Pb) collisions at s N N = 5.02 TeV, and lead–lead (Pb–Pb) collisions at s N N = 2.76 TeV. For mesons (baryons), the contributions of two (three) constituent quarks are considered, in which each quark contributes to hadron transverse momentum to obey the revised phenomenological Tsallis transverse momentum distribution for Maxwell–Boltzmann particles (the TP-like function, in short) with isotropic random azimuthal angles. Three main parameters, namely, the revised index a 0 , effective temperature T, and entropy-related index n, are obtained, showing the same tendency for both small and large systems with respect to the centrality (or multiplicity) of events, the rest mass of hadrons, and the constituent mass of quarks. [ABSTRACT FROM AUTHOR]

A method for reconstructing spectra of short-range charged particles in experimental investigations of stopped-pion absorption by nuclei is described. This approach is based on the use of a monitor system, which consists of two Si detectors, and a "live" target, which is also a Si detector. By simultaneously analyzing data from the monitor detectors and the live target, it is possible to determine the depth at which a pion stops inside the target. It is shown that the use of the presented "aiming" method with targets ∼0.1 g/cm2 thick makes it possible to correctly reconstruct the energy spectra of 3He and 4He isotopes in the energy range of 16−35 MeV. [ABSTRACT FROM AUTHOR]

In the wake of recent measurements of ratios of semileptonic branching fractions: R J / ψ , R D and R D ∗ reported by the LHCb, BELLE and HFLAV Collaborations, we calculate invariant form factors for the exclusive semileptonic B c -meson decays to radially excited charmonium and charm meson states in the full kinematical region within the framework of relativistic independent quark (RIQ) model. We evaluate the lepton mass effect in the decay processes induced by b → c , u transition at the quark level. Our predictions on branching fractions for B c → η c / ψ (n S) are found ∼ 10 - 2 - 10 - 4 and that for B c → D ∗ (n S) are ∼ 10 - 4 in their e - decay modes, which lie within the detection accuracy of current experiment. Our predictions on branching fractions, forward backward asymmetry and asymmetry parameter are found in reasonable agreement with other model predictions; which can hopefully be tested in future experiments at LHC and Tevatron. Our predicted observable R in this sector are found comparable to other standard model (SM) predictions that violate the lepton flavor universality hinting at new physics beyond SM. [ABSTRACT FROM AUTHOR]

Mass renormalization of the electron in configurations such as metallic hydride surfaces due to electromagnetic field fluctuations leads to mass enhancement of the electron, which is known as the heavy electron. The effective mass renormalization has substantial consequences in the theory of electromagnetic field interaction with matter (QED). One of the fascinating effects appears when an external photon interacts with the heavy electron. In this case, the wavelength of the scattered photon from the electron increases and the hard photon turns into a soft photon. In this paper, we present a novel mechanism to show how the heavy electron results in hard photon absorption. [ABSTRACT FROM AUTHOR]

The relativistic Bethe–Salpeter method is adopted to study the OZI-allowed strong decays of the 2 + state B 2 ∗ (5747) 0 , with emphasis on the relativistic corrections. We first study the partial waves in the wave functions used and find that there are P, D, and F partial waves in the B 2 ∗ (5747) 0 meson, with ratios of P / D / F = 1 : 0.421 : 0.051 . We also find that S / P / D = 1 : 0.354 : 0.046 for B ∗ , and S / P = 1 : 0.343 for the B meson. The large components of the D wave in B 2 ∗ (5747) 0 and the P wave in B (∗) mean that large relativistic effects exist in these states. Second, we calculate the strong decays, and the total decay width Γ (B 2 ∗ (5747) 0) = 25.9 MeV and the branching fraction Γ (B 2 ∗ (5747) 0 → B ∗ π) / Γ (B 2 ∗ (5747) 0 → B π) = 0.96 obtained are consistent with experimental data. Third, we study the contributions of different partial waves in the initial and final wave functions, and find that the relativistic effects are about 15 % and 11 % for B 2 ∗ (5747) 0 → B π and B 2 ∗ (5747) 0 → B ∗ π , respectively, which are much smaller than our expected effects, showing that the relativistic corrections cancel each other in these decays. [ABSTRACT FROM AUTHOR]

We perform a theoretical study on the D D ¯ K three body system, using the fixed center approximation to the Faddeev equations, considering the interaction between D and K, D and D ¯ from the chiral unitary approach. We assume the scattering of K meson on a clusterized system D D ¯ , where a scalar meson X(3720) could be formed. Thanks to the strong DK interaction, where the scalar D s 0 ∗ (2317) meson is dynamically generated, a resonance structure shows up in the modulus squared of the three body K- (D D ¯) X (3720) scattering amplitude and supports that a D D ¯ K bound state can be formed. The result is in agreement with previous theoretical studies, which claim a new excited hidden charm K meson, K c c ¯ (4180) with quantum numbers I (J P) = 1 2 (0 -) and mass about 4180 MeV. It is expected that these theoretical results motivate its search in experimental measurements. [ABSTRACT FROM AUTHOR]

Spectrum of the low-lying hidden- and double-charm tetraquark states are investigated in a nonrelativistic quark potential model, where the instanton-induced interaction is taken as the residual spin-dependent hyperfine interaction between quarks. The model parameters are fixed by fitting the spectrum of the ground hadron states. Our numerical results show that masses of several presently studied tetraquark states are close to those of the experimentally observed candidates of exotic meson, which indicates that the corresponding compact tetraquark components may take considerable probabilities in those observed exotic states. [ABSTRACT FROM AUTHOR]

We reanalyze the Λ b → p transition form factors in the perturbative QCD (PQCD) approach by including higher-twist light-cone distribution amplitudes (LCDAs) of a Λ b baryon and a proton. The previous PQCD evaluation performed decades ago with only the leading-twist Λ b baryon and proton LCDAs gave the form factors, which are two orders of magnitude smaller than indicated by experimental data. We find that the twist-4 Λ b baryon LCDAs and the twist-4 and -5 proton LCDAs contribute dominantly, and the enhanced form factors become consistent with those from lattice QCD and other nonperturbative methods. The estimated branching ratios of the semileptonic decays Λ b → p ℓ ν ¯ ℓ and the hadronic decay Λ b → p π are also close to the data. It implies that the b quark mass is not really heavy enough, and higher-power contributions play a crucial role, similar to the observation made in analyses of B meson transition form factors. With the formalism established in this work, we are ready to study various exclusive heavy baryon decays systematically in the PQCD approach. [ABSTRACT FROM AUTHOR]

We compute the hadronic light-by-light scattering contribution to the muon g - 2 from the charm quark using lattice QCD. The calculation is performed on ensembles generated with dynamical (u, d, s) quarks at the SU(3) f symmetric point with degenerate pion and kaon masses of around 415 MeV. It includes the connected charm contribution, as well as the leading disconnected Wick contraction, involving the correlation between a charm and a light-quark loop. Cutoff effects turn out to be sizeable, which leads us to use lighter-than-physical charm masses, to employ a broad range of lattice spacings reaching down to 0.039 fm and to perform a combined charm-mass and continuum extrapolation. We use the η c meson to define the physical charm-mass point and obtain a final value of a μ HLbL , c = (2.8 ± 0.5) × 10 - 11 , whose uncertainty is dominated by the systematics of the extrapolation. Our result is consistent with the estimate based on a simple charm-quark loop, whilst being free of any perturbative scheme dependence on the charm mass. The mixed charm–light disconnected contraction contributes a small negative amount to the final value. [ABSTRACT FROM AUTHOR]

As a hypothetic particle, a sterile neutrino can exist in types of new physics models. In this work by investigating flavor violating semileptonic and leptonic decays of K,D, and B mesons induced by the GeV scale sterile neutrino, we explore its allowed regions in parameter space. Analytically, we derive branching fractions of semileptonic decay M+h→M+lℓ+1ℓ−2 and leptonic decay M0→ℓ−1ℓ+2, including the contribution from a new box diagram contribution due to the massive sterile neutrino. Imposing its mass ranges, we numerically analyze the active-sterile neutrino mixings in corresponding regions. We find that when the sterile neutrino mass is located in between pion and kaon mass, K+→π+e±μ∓ gives the strongest constraint while B+→π+e±μ∓ provides the dominated constraint when its mass in between of kaon and B meson. If the sterile neutrino is even heavier than Bmesons, the LHCb B0s→μ±e∓ results gives the strongest constraint. [ABSTRACT FROM AUTHOR]

Following our previous work [C. Y. Liu, Mod. Phys. Lett. A 36, 2150080 (2021), doi:10.1142/S0217732321500802], we investigate the masses of some pseudoscalar mesons which have the anomalous decays from axial anomaly (the Adler–Bell–Jackiw anomaly). We apply a non-perturbative mass formula to study the neutral single flavor pseudoscalar meson (f f ̄). We find the mass of pseudoscalar meson (c c ̄) (m (c c ̄) ≈ 7. 6 GeV) which can solve the problem of double c c ̄ production in e + e − annihilation at s ≈ 1 0. 6 GeV and obtain the mass of pseudoscalar meson (b b ̄) (m (b b ̄) ≈ 2 8. 4 GeV) which is the same as the invariant mass of μ + μ − pairs produced in association with b jet in p p -collisions at the LHC. We generalize this formula to three flavors pseudoscalar mesons, we obtain the mass of η ′ meson (m η ′ ≈ 9 6 1 MeV) which is almost the same as the experimental value (m η ′ exp ≈ 9 5 8 MeV). [ABSTRACT FROM AUTHOR]