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The pervasiveness of deep space radiation remains a confounding factor for the transit of humans through our solar system. Spacecraft shielding both protects astronauts but also contributes to absorbed dose through galactic cosmic ray interactions that produce secondary particles. The resultant biological effects drop to a minimum for aluminum shielding around 20 g/cm2 but increase with additional shielding. The present work evaluates for the first time, the impact of secondary pions on central nervous system functionality. The fractional pion dose emanating from thicker shielded spacecraft regions could contribute up to 10% of the total absorbed radiation dose. New results from the Paul Scherrer Institute have revealed that low dose exposures to 150 MeV positive and negative pions, akin to a Mars mission, result in significant, long-lasting cognitive impairments. These surprising findings emphasize the need to carefully evaluate shielding configurations to optimize safe exposure limits for astronauts during deep space travel.

The multiplicity dependence of the production of the charm mesons in pp collisions at s=7TeV and 13TeV as measured by ALICE experiment has been investigated using Pythia 8 event generator by studying the effect of various processes at partonic level such as the effect of different modes of color reconnections and rope hadronization. The relative yields (Yield∕〈Yield〉) of D-mesons and J∕ψ as a function of relative charged particle multiplicity for various transverse momentum (pT) ranges as measured by the ALICE experiment are in reasonable agreement with the estimations of Pythia 8 model within the framework of microscopic processes. The relative yields of B mesons for various pT intervals (1c) have also been predicted in pp collisions at s=7TeV and s=13TeV. [ABSTRACT FROM AUTHOR]

The possible appearance of the effects of local parity breaking in the QCD medium formed in heavy ion collisions due to violation of chiral symmetry can be quantified by corresponding chiral chemical potential μ5. The experimental observables sensitive to the effects of local parity violation in strong interaction include search for polarization splitting of the ρ0 and ω0 mesons via angular dependence of spectral functions in their decay to leptons. In this paper, we study the space-time evolution and fluctuations of μ5 using relativistic hydrodynamics and estimate their effect on the light vector meson polarization splitting in Pb–Pb collisions at LHC energy. [ABSTRACT FROM AUTHOR]

A partial-wave analysis (PWA) for the photoproduction of pseudoscalar mesons on a nucleon using truncation in total angular momentum j is discussed. A formalism is described that can be used for investigating discrete ambiguities. Considerable attention is devoted to the connection of this type of PWA with that based on the truncation in orbital angular momentum l. [ABSTRACT FROM AUTHOR]

We have developed the covariant approach for the partial wave analysis of the radiative decay of the vector meson into two pseudoscalar mesons based on the orbital momentum- intrinsic spin decomposition. This allowed us to include the data on the radiative decay into a large data base for analysis of the meson production reactions. The correspondence between partial wave amplitudes extracted in our approach and those extracted in the helicity basis is determined. [ABSTRACT FROM AUTHOR]

The bioreduction characteristics and mechanisms of Cr(VI) onto Bacillus cereus RCr enhanced by ferric citrate were investigated. The optimum conditions were initial pH 9, temperature 40 °C, inoculation amount 4%, and glucose 3 g/L, respectively. The addition of 1.5 g/L ferric citrate increased the average reduction rate from 120.43 to 220.61 mg/(L∙h) compared with the control (without ferric citrate). The binding capacity of Cr(III) on the cell surface increased to 21%, in which the precipitates were mainly CrO(OH), Cr2O3, and FeCr2O4. Cell membrane was the main site of reduction, related important functional groups: − COOH, C-H, − NH2, C = C, and P-O. Fe(III) increased the yield of NADH and cytochrome c by approximately 48.51% and 68.63%, which significantly facilitated the electron generation and electron transfer, thus increasing the amount of electrons in the bioreduction of heavy metals by an average of 110%. Among the electrons obtained by Cr(VI), the proportion of indirect reduction mediated by Fe(III)/Fe(II) shuttle was 62% on average, whereas direct reduction mediated by reductase was 38%. These results may provide insights into the bioreduction process by bacteria enhanced by Fe(III) for detoxification of heavy metals with multiple valences, as an important step towards improving microbial remediation. [ABSTRACT FROM AUTHOR]

Cubic, perovskite‐structure ABO3‐ and A1−xA'xBO3‐type oxides have been investigated extensively while their hexagonal structure versions have not, even though they are multiferroic and can form heterostructures with hexagonal 2D materials. In particular, multiferroic 2D epilayers may lead to strong magnetoelectric coupling. Hexagonal RFeO3 ferrites, where R is a rare‐earth element (Lu, Yb, etc.), are excellent candidates, but their ferromagnetism is weak. In this work, density‐functional‐theory (DFT) calculations are employed and first show that heavy electron doping of hexagonal LuFeO3 (h‐LFO), namely Lu1−xHfxFeO3 (h‐LHFO), leads to spin‐disproportionation of the Fe sublattices and, especially for x = 1/2 and 2/3, to robust, room‐temperature, out‐of‐plane, collinear ferrimagnetism that is stabilized by a Jahn–Teller metal‐to‐insulator transition. h‐LHFO/h‐2D heterostructures are then shown, where h‐2D is the FE/FM monolayer MnSTe, to stabilize skyrmions without an external magnetic field and their chirality is controlled by an external electric field through the h‐LHFO polarization, opening up a new realm for magnetoelectric applications. [ABSTRACT FROM AUTHOR]

Nucleon–nucleon short range correlations (SRCs) in nuclei are important part of the nuclear structure and have been a subject of intensive studies in the last years. These objects represent temporary fluctuations in average nuclear matter density that occur when two or more nucleons separated by about 1 fm = 10–13 cm. Inspired by recent theoretical and experimental progress in understanding of SRC we reanalyzed our data on the production of high momentum and mesons emitted from nuclear targets irradiated by a proton beam. One of the basic properties of SRCs is the universality which means that they are equally involved in the creation of different hadrons on different nuclei, reflecting the properties of nuclear matter. So far, the property of universality has been observed in electron–nuclear collisions for the breakup of proton–neutron correlations, as well as in proton–nuclear collisions for the production of cumulative pions with high momenta. Both processes involve only light quarks. In this letter, we report the first observation of SRC universality in kaon production on nuclei in the kinematic region of high energy–momentum transfers thereby extending the investigation of the SRC universality to the sector of strange quarks. [ABSTRACT FROM AUTHOR]

We investigate the transverse momentum spectra of identified particles at 7 and 13 TeV in pp collisions in the framework of the blast wave model with Tsallis statistics (TBW). Based on experimental data by ALICE Collaboration, we observe that the model describes the p T spectra well with the common Tsallis temperature (T) and flow velocity (β T ) but separate non-extensive parameters (q) for baryons and mesons. The parameter dependence on multiplicity as well as on collision energy is investigated, and a strong dependence on the former while a weak dependence on the latter is reported. The extracted parameters in this work consist of the initial temperature (T i ), the average transverse momentum (〈 p T 〉), the Tsallis temperature (T), the flow velocity (β T ), and the non-extensive parameter (q). These parameters are found to increase a little with increasing energy, however, they (except the parameter q) decrease significantly with decreasing multiplicity. We observe that β T drops to zero at high multiplicity, while, T and q do not change their behavior. Furthermore, our analysis explore the correlations among different parameters, including associations with the charged particle multiplicity per unit pseudorapidity ( 〈 d N ch / d η 〉 ). The correlations between T and β T , T and 〈 d N ch / d η 〉 , β T and 〈 d N ch / d η 〉 , T i and 〈 p T 〉 and T i and 〈 d N ch / d η 〉 demonstrates a positive relationship, while, the correlation between T and q − 1, and q − 1 and 〈 d N ch / d η 〉 is negative. Finally, we implement an extra flow correction on the T parameter. Our findings reveal that the Doppler-corrected temperature parameter aligns closely with the T in scenarios with lower multiplicities. However, as the multiplicity increases, a noticeable divergence emerges between these parameters, indicating a widening separation between them. [ABSTRACT FROM AUTHOR]

In this work, the doubly-charm and doubly-bottom pentaquark molecular states D (∗) Σ c (∗) and B (∗) Σ b (∗) are studied via the QCD sum rules. Sixteen color singlet-singlet type currents with the definite isospin-spin-parity I J P are constructed to interpolate the corresponding hadronic states with the same quantum numbers. The masses and pole residues of those doubly-heavy pentaquark molecular states are calculated, the results show that their masses are all below the corresponding meson-baryon thresholds, which means that they are possible bound states, not resonant states, moreover, the possible decay channels for the doubly-charm molecular states are given. [ABSTRACT FROM AUTHOR]

The recently introduced topological heavy fermion model (THFM) provides a means for interpreting the low-energy electronic degrees of freedom of the magic angle twisted bilayer graphene as hybridization amidst highly dispersing topological conduction and weakly dispersing localized heavy fermions. In order to understand the Landau quantization of the ensuing electronic spectrum, a generalization of THFM to include the magnetic field B is desired, but currently missing. Here we provide a systematic derivation of the THFM in B and solve the resulting model to obtain the interacting Hofstadter spectra for single particle charged excitations. While naive minimal substitution within THFM fails to correctly account for the total number of magnetic subbands within the narrow band i.e., its total Chern number, our method—based on projecting the light and heavy fermions onto the irreducible representations of the magnetic translation group— reproduces the correct total Chern number. Analytical results presented here offer an intuitive understanding of the nature of the (strongly interacting) Hofstadter bands. The recently-developed topological heavy fermion model explains the low energy electrons of magic-angle twisted bilayer graphene as a hybridization between states localized at AA stacking sites and itinerant topological states, denoted by f and c electrons in analogy to heavy fermion systems. Here, the authors extend this model to a nonzero magnetic field, obtaining interacting Hofstadter spectra in the flatband limit by analytic methods. [ABSTRACT FROM AUTHOR]

Ratios ms/md and mu/md of the light quark masses have been determined from expressions for squared masses of pseudoscalar mesons and obtained with an accuracy of the second order in chiral symmetry breaking. The fit of the theoretical expressions for and to their phenomenological values leads to a functional relation between the ratios ms/md and mu/md, which is described by a third-order curve. The application of the lattice calculation result ms/mud = 27.23(10), where mud = (mu + md)/2, reported by the flavor lattice averaging group (FLAG) for the case of four quark flavors provides an additional constraint, which significantly reduces the error (~2%) for the ratio mu/md = 0.455(8). The absolute values of the quark masses have been then obtained. [ABSTRACT FROM AUTHOR]

This research study primarily will focus on investigating how the topological effects influence the eigenvalue solutions in the presence of a hot-dense medium. To accomplish this, we employ the non-relativistic Schrödinger wave equation by taking into consideration both the quantum flux field and interaction potential. Through this approach, we determine the energy eigenvalues and their corresponding wave functions using the Nikiforov–Uvarov method. Our findings indicate that when we consider both the topological effects and the magnetic flux, Φ , there is a noticeable reduction in the binding energy within the hot-dense medium. Additionally, we analyze the role of the baryonic potential in shaping the binding energy within the (T , u b) plane. Interestingly, it is evident that the influence of the baryonic potential becomes more pronounced as its values decrease. [ABSTRACT FROM AUTHOR]

A novel observable, the double nuclear modification factor, is proposed to probe simultaneously the initial and final state effects in nucleus–nucleus collisions. An interesting competition between the combinatorial enhancement in the double parton scattering and the suppression due to parton energy loss can be observed in the production rate of two hard particles. In particular, the production of mesons in association with a W boson is not suppressed but is enhanced in the region of moderate transverse momenta, unlike the case of unassociated (inclusive) production. At the same time, in the region of high enough transverse momenta the nuclear modification factor for associated production converges to that of unassociated . [ABSTRACT FROM AUTHOR]

In this paper, we perform a complete non-relativistic study of the improved class of inversely quadratic Yukawa plus Hulthén potential (ICIQYHP) model in the context of three-dimensional non-relativistic non-commutative quantum phase-space (3D-NRNCPS) symmetries impacted by perturbed spin–orbit interaction and the external magnetic fields for the homogeneous (N2 and O2) and heterogeneous (CO and NO) diatomic molecules and the heavy meson systems, such as charmonium (cc) and bottomonium (bb) using generalized Bopp's shifts method and standard perturbation theory with the Greene–Aldrich approximation to the centrifugal barrier. The new non-relativistic energy equation and eigenfunction for the ICIQYHP in the presence of deformation phase–space are obtained to be sensitive to the atomic quantum numbers (j , l , s , and m), the mixed potential depths ( V 0 1 , V 2 1 , V 1 1 and V 3 1 ), the screening parameter δ 0 , and non-commutativity parameters (Φ / η ¯ , χ / χ ¯ and ζ / ζ ¯). The critical particular cases in 3D-NRNCPS symmetries have been obtained by adjusting the parameters of the ICIQYHP, such as the improved Hulthén potential, the improved Coulomb potential, and the improved inversely quadratic Yukawa potential. We have also studied the spin-averaged mass spectra of the heavy mesons and the thermo-magnetic properties under the class of inversely quadratic Yukawa plus Hulthén potential model in 3D-NRQM and 3D-NRNCPS symmetries. This research can potentially be applied to atomic, condensed matter, nuclear, molecular physics, and chemical physics. [ABSTRACT FROM AUTHOR]

We provide an update on our semi-classical transport approach for quarkonium production in high-energy heavy-ion collisions, focusing on J / ψ and ψ (2 S) mesons in 5.02 TeV Pb-Pb collisions at the Large Hadron Collider (LHC) at both forward and mid-rapidity. In particular, we employ the most recent charm-production cross sections reported in pp collisions, which are pivotal for the magnitude of the regeneration contribution, and their modifications due to cold-nuclear-matter (CNM) effects. Multi-differential observables are calculated in terms of nuclear modification factors as a function of centrality, transverse momentum, and rapidity, including the contributions from feeddown from bottom hadron decays. For our predictions for ψ (2 S) production, the mechanism of sequential regeneration relative to the more strongly bound J / ψ meson plays an important role in interpreting recent ALICE data. [ABSTRACT FROM AUTHOR]

In heavy-ion collisions at intermediate energies, the production and propagation of Δ particles are crucial to understanding the nuclear equation of state and inferring the properties of nuclear matter at high densities. Based on the self-consistent relativistic Boltzmann-Uehling-Uhlenbeck (RBUU) transport theory, by introducing the isovector ρ meson exchange into the effective Lagrangian and adopting the density-dependent coupling constants, the detailed expressions for isospin-dependent in-medium N Δ → N Δ elastic cross sections σ N Δ ∗ have been calculated. The energy and density dependence of the isospin-related σ N Δ ∗ as well as the total contributions of σ , ω and ρ meson fields are analyzed. It is found that the total σ N Δ ∗ has a sensitive center-of-mass energy dependence at lower energies while exhibiting a slight increase as the center-of-mass energy increases. The isospin effect between different isospin-separated channels weakens as the energy and/or density increases. The isospin effect on the density- and energy-dependent in-medium N Δ elastic cross sections is dominantly caused by the delicate balance of the isovector ρ meson exchange. [ABSTRACT FROM AUTHOR]

Partial widths and double- and single-differential distributions are calculated on the framework of the Standard Model for the four-lepton decays , where = and . The contribution of virtual-photon emission by a light quark and a heavy quark, the bremsstrahlung contribution from charged leptons in the final state, the weak-annihilation contribution, and the contribution of wide vector resonances are taken into account. The contribution of narrow and resonances is excluded. Virtual-photon emission by the light quark of a meson is described on the framework of the vector-meson-dominance model, within which only the contributions of the lightest vector mesons containing pairs are taken into account. For the meson, this is the resonance. For the meson, the contributions of the and resonances are taken into account. Two possibilities are considered in the present study. The first is that where the contributions of the narrow and mesons are excluded from the partial widths with respect to the corresponding decays. The second is that where the contributions of narrow resonances are taken into account in partial widths. The problem of the influence of the subtraction procedure on the partial widths with respect to the decays is studied individually. [ABSTRACT FROM AUTHOR]

First results on -dependence measurements in inclusive meson production in interactions ( , Al, Cu, Sn, and W) are presented at GeV/c. The ratios of the differential cross sections of four of these nuclei to the differential cross section on aluminum were measured and the dependence of these cross sections on the atomic of the nucleus was studied. The measurements were carried out in the kinematic region of the Feynman variable and transverse momentum GeV/c. mesons were detected in the decay mode at the SPASCHARM experimental setup using negative charged beams at beamline 14 of the U-70 accelerator complex. [ABSTRACT FROM AUTHOR]

The Spin Physics Detector (SPD) at the Nuclotron based Ion Collider fAcility (NICA) is designed to study nucleon spin structure in the three dimensions. At design energy, the leading mechanism of charm meson pair production in proton–proton collisions is the gluon fusion. At the SPD, charmed mesons can be detected via their hadronic decay channels. While these measurements are challenging due to orders of magnitude larger hadronic background, we demonstrate the capacity to obtain asymmetry measurements that can make an impact on the present understanding of gluon Transverse Momentum Dependent (TMD) distributions inside protons. [ABSTRACT FROM AUTHOR]

The recent results on charmonium production at BESIII are reviewed, including the observation of charmonium-like states in the processes of electron–positron annihilation into , , , and final states, as well as the study of the prompt inclusive production of the and mesons. [ABSTRACT FROM AUTHOR]

The effects of external magnetic fields on monopoles, spectra of the overlap Dirac operator, instantons, and the mass of the eta-prime meson are examined by conducting lattice QCD simulations. The uniform external magnetic field is applied to gauge field configurations with flavor quarks. The bare quark masses are tuned in order to obtain the physical values of the pion mass and of the ratio. Standard configurations and configurations with an applied external magnetic field are generated in the color confinement and deconfinement phases. The intensity of the external magnetic field varies from to . To examine the influence of the external magnetic field on monopoles, we first calculate the monopole density, measure the lengths of the monopole loops, and compare them with the absolute value of the Polyakov loops. Next, using the generated configurations, we compute the eigenvalues and eigenvectors of the overlap Dirac operator, which preserves exact chiral symmetry. To investigate how external magnetic fields affect the spectra of the overlap Dirac operator, we compute spectral densities, compare fluctuations of the eigenvalues of the overlap Dirac operator with the predictions of random matrix theory, and estimate the number of instantons and anti-instantons from the topological charges. In addition, we analyze smearing effects on these observables and chiral symmetry breaking. Finally, we calculate the decay constant of the pseudoscalar meson, the chiral condensate, and the square mass of the eta-prime meson using the eigenvalues and eigenvectors. We then extrapolate the numerical results in the chiral limit and demonstrate the effects of external magnetic fields on the extrapolation results. This article presents preliminary results. [ABSTRACT FROM AUTHOR]

Motivated by the study of heavy–light meson production within the framework of heavy quark effective theory (HQET) factorization, we extend the factorization formalism for a rather complicated process W + → B +ℓ+ℓ− in the limit of a nonzero invariant squared mass of the dilepton, q 2, at the lowest order in 1/ mb up to |$\mathcal {O}(\alpha _s)$|⁠. The purpose of the current study is to extend the HQET factorization formula for the W + → B +ℓ+ℓ− process and subsequently compute the form factors for this channel up to next-to-leading-order corrections in α s . We explicitly show that the amplitude of the W + → B +ℓ+ℓ− process can also be factorized into a convolution between the perturbatively calculable hard-scattering kernel and the nonperturbative yet universal light-cone distribution amplitude (LCDA) defined in HQET. The validity of the HQET factorization depends on the assumed scale hierarchy mW ∼ mb ≫ ΛQCD. Within the HQET framework, we evaluate the form factors associated with the W + → B +ℓ+ℓ− process, providing insights into its phenomenology. In addition, we also perform an exploratory phenomenological study on W + → B +ℓ+ℓ− by employing an exponential model for the LCDAs for the B + meson. Our findings reveal that the branching ratio for W + → B +ℓ+ℓ− is below 10−10. Although the branching ratios are small, this channel in high-luminosity LHC experiments may serve to further constrain the value of λ B . [ABSTRACT FROM AUTHOR]

The paper studies a strong coupling constant between π meson and octet baryon using the hard-wall AdS/QCD model, which considers SU(3)f symmetry-breaking effects. Briefly mentioned are profile functions for pseudoscalar meson and baryon fields. The obtained baryon coupling constants are in agreement with those obtained in theoretical calculations. [ABSTRACT FROM AUTHOR]

We present our first set of results for charm physics, using the mixed-action setup introduced in a companion paper [1]. Maximally twisted Wilson valence fermions are used on a sea of non-perturbatively O(a)-improved Wilson fermions, made up by CLS N f = 2 + 1 ensembles. Our charm-sector observables are free from O (a m c) discretisation effects, without need of tuning any improvement coefficient, and show continuum-limit scaling properties consistent with leading cutoff effects of O (a 2) . We consider a subset of CLS ensembles – including four values of the lattice spacing and pion masses down to 200 MeV – allowing to take the continuum limit and extrapolate to the physical pion mass. A number of techniques are incorporated in the analysis in order to estimate the systematic uncertainties of our results for the charm quark mass and the D (s) -meson decay constants. This first study of observables in the charm sector, where the emphasis has been on the control of the methodology, demonstrates the potential of our setup to achieve high-precision results. [ABSTRACT FROM AUTHOR]

We look at the mass spectra of the D ± , D ± ∗ , D s ± ∗ , D s ± , B ± , B ± ∗ , B s 0 ∗ , B s 0 , B c ± ∗ , B c ± , ρ , π , and ω mesons using a relativistic square root potential. Before looking at the mass spectra, we have to figure out the model parameters, which are U 0 = − 1. 1 1 5 GeV and a = 0. 8 8 5 GeV. The calculated result of D ± (1. 8 6 1 GeV) , D ± ∗ (2. 0 1 0 GeV) , D s ± (1. 9 0 3 GeV) , D s ∗ ± (2. 1 1 2 GeV) , B ± (5. 2 6 4 GeV) , B ± ∗ (5. 3 2 7 GeV) , B s 0 (5. 3 4 5 GeV) , B s 0 ∗ (5. 4 2 3 GeV) , B C ± (5. 9 5 6 GeV) , B C ± ∗ (6. 2 7 7 GeV) , findings of this study exhibit a notable concurrence with the experimental observations and pertinent theoretical projections. We estimate the decay constant, leptonic decay width, semileptonic decay width, and branching fractions of pseudoscalar and vector mesons, specifically B and D mesons, while keeping the model parameters unchanged. The pseudoscalar decay constants and partial decay widths of "B and D-mesons" reasonably agree with the theoretical predictions, lattice quantum chromodynamics (LQCD) calculations, and experimental data. Moreover, we have efficiently found the values for these mesons' leptonic decay width and branching fraction, matching the experimental findings and theoretical forecasts. The calculated values of semileptonic decays are D 0 → π − e + ν e (2. 8 9 2 × 1 0 − 3) , D + → π 0 e + ν e (3. 6 6 9 × 1 0 − 3) , D + → ρ 0 e + ν e (1. 6 5 9 × 1 0 − 3) and D + → η ′ e + ν e (3. 1 7 × 1 0 − 4) , D S + → φ e + ν e (2. 5 9 9 × 1 0 − 2) , D S + → η e + ν e (2. 3 0 3 × 1 0 − 2) , the proximity of the observed results to experimental and certain theoretical models is evident. [ABSTRACT FROM AUTHOR]

The proton spin puzzle has inspired a vast programme of experiments and theoretical work challenging our understanding of QCD and its role in the structure of hadrons. The proton's internal spin structure is connected to chiral symmetry and, through gluon degrees of freedom in the flavor singlet channel, to the physics of the η ′ meson. Why do quarks contribute just about one third of the proton's spin? Why are η ′ mesons and their interactions so sensitive to gluonic degrees of freedom? We review the status of these topics and some key observables for forthcoming experiments. [ABSTRACT FROM AUTHOR]

The two-body leptonic decays of both light and heavy-charged mesons X l 2 ± are investigated in the first Born approximation in the presence of a monochromatic and circularly polarized laser field. As a result of using Volkov functions, the analytic study of these processes has brought a change in the parameters associated with each decay process. The decay width, lifetime, and branching ratio of each decay process are affected by increasing the classical parameter ξ of the meson. A comparison between the matter decay X l 2 + and that of the anti-matter X l 2 - in the presence of a circularly polarized laser wave, indicates that increasing laser field strength (increasing the classical parameter ξ ) can induce a slight dominance of matter over antimatter or vise versa. [ABSTRACT FROM AUTHOR]

The Schwinger confinement mechanism stipulates that a massless fermion and a massless antifermion are confined as a massive boson when they interact in the Abelian QED interaction in (1+1)D.If we approximate light quarks as massless and apply the Schwinger confinement mechanism to quarks, we can infer that a light quark and a light antiquark interacting in the Abelian QED interaction are confined as a QED meson in (1+1)D. Similarly, a light quark and a light antiquark interacting in the QCD interaction in the quasi-Abelian approximation will be confined as a QCD meson in (1+1)D. The QED and QCD mesons in (1+1)D can represent physical mesons in (3+1)D when the flux tube radius is properly taken into account. Such a theory leads to a reasonable description of the masses of π 0 , η , and η ′ , and its extrapolation to the unknown QED sector yields an isoscalar QED meson at about 17 MeV and an isovector QED meson at about 38 MeV. The observations of the anomalous soft photons, the hypothetical X17 particle, and the hypothetical E38 particle bear promising evidence for the possible existence of the QED mesons. Pending further confirmation, they hold important implications on the properties on the quarks and their interactions. [ABSTRACT FROM AUTHOR]

The production of ψ(2S) mesons in proton-lead collisions at a centre-of-mass energy per nucleon pair of s NN = 8.16 TeV is studied with the LHCb detector using data corresponding to an integrated luminosity of 34 nb−1. The prompt and nonprompt ψ(2S) production cross-sections and the ratio of the ψ(2S) to J/ψ cross-section are measured as a function of the meson transverse momentum and rapidity in the nucleon-nucleon centre-of-mass frame, together with forward-to-backward ratios and nuclear modification factors. The production of prompt ψ(2S) is observed to be more suppressed compared to pp collisions than the prompt J/ψ production, while the nonprompt productions have similar suppression factors. [ABSTRACT FROM AUTHOR]

In classical field theory, radiation does not reflect off of reflectionless kinks. In quantum field theory, radiation quanta, called mesons, can be reflected. We provide a general analytical formula for the leading order amplitude and probability for the elastic scattering of mesons off of reflectionless quantum kinks. In the case of the Sine-Gordon model we verify that, due to a cancellation of six contributing processes, our general formula yields an amplitude of zero, as is required by integrability. [ABSTRACT FROM AUTHOR]

This study focuses on the presence of (multi)fractal structures in hadronic matter through the momentum distributions of mesons produced in proton-proton collisions between 23 GeV and 63 GeV. The analysis demonstrates that the q-exponential behaviour of the particle momentum distributions is consistent with fractal characteristics, exhibiting fractal structures in confined hadronic matter with features similar to those observed in the deconfined quark-gluon plasma (QGP) regime. Furthermore, the systematic analysis of meson production in hadronic collisions at energies below 1 TeV suggests that specific fractal parameters are universal, independently of confinement or deconfinement, while others may be influenced by the quark content of the produced meson. These results pave the way for further research exploring the implications of fractal structures on various physical distributions. [ABSTRACT FROM AUTHOR]

Belle II collects data at the asymmetric electron-positron collider SuperKEKB, which operates with a centre-of-mass energy at, or close to, the mass of the Υ (4 S) resonance. The Υ (4 S) lies just above the kinematic threshold for B-meson-pair production, so Belle II collects a large sample of B + B - and B 0 B ¯ 0 pairs that are unaccompanied by other particles. The low-multiplicity final state and constrained kinematics allow many measurements with missing energy and neutral mesons in the final state that complement the B-physics measurements made by LHCb. In addition to B mesons, this center-of-mass energy has a similar cross section for electron-positron annihilation to c c ¯ and τ + τ - pairs, meaning Belle II also makes measurements of charm hadron and tau lepton properties. Finally, unique searches for hypothesized dark-sector particles with masses in the range 100 MeV–10 GeV are possible. This article reviews the current results from the Belle II experiment. [ABSTRACT FROM AUTHOR]

This article elucidates the pivotal role of b-mesons and bottomonium states in exploring the existence and properties of hot QCD matter (commonly known as quark-gluon-plasma (QGP) produced within the crucible heavy-ion collision experiments). Owing to the complex and confounding nature of strong interaction force the direct detection of probing the hot QCD matter is not feasible. In light of this, investigating the dynamics of b-quarks and anti-quarks within the hot QCD medium emerges as an invaluable indirect probe. The impact of b-quarks and the mesons spans a spectrum of interesting domains regarding the physics of QCD at finite temperature, encompassing the QCD phase transition, color screening, quarkonia dissociation, heavy quark energy loss and collective flow, anisotropic aspects, and strongly coupled nature of hot QCD medium. These aspects underscore the indispensable nature of B-mesons in the quest to create and explore the complex nature of strong interaction force through the QGP/hot QCD matter. In this context, we mainly focus on works related to transport studies of b-mesons in hot QCD medium, lattice QCD, and effective field theory studies on bottomonium states, and finally, open quantum system frameworks to quarkonia to explore the properties of hot QCD medium in relativistic heavy-ion collision experiments. [ABSTRACT FROM AUTHOR]

We overview the current status and future perspectives of the QCD-based method of light-cone sum rules. The two main versions of these sum rules, using light-meson and B-meson distribution amplitudes are introduced and the most important applications of the method are discussed. We also outline open problems and future perspectives of this method. [ABSTRACT FROM AUTHOR]

We discuss the main issues in dealing with heavy quarks on the lattice and shortly present the different approaches used. We discuss a selection of computations covering first the b-quark mass and the B (s) meson decay constants as the consolidated results (neglecting isospin breaking corrections). In the second part, we consider recent calculations of form factors for tree-level semileptonic decays with emphasis on the tensions between the results produced by different collaborations. We propose benchmark quantities and tests suited to investigate the origin of such tensions. Finally, we review computations of the bag parameters parameterising neutral meson mixing and provide an overview on a few recent developments in the field. [ABSTRACT FROM AUTHOR]

Two newly proposed Regge trajectory relations are employed to analyze the heavy-light systems. One of the relations is M = m 1 + m 2 + C ′ + β x x + c 0 x , (x = l , n r) . Another reads M = m 1 + C ′ + β x 2 (x + c 0 x) + 4 3 π β x m 2 3 / 2 (x + c 0 x) 1 / 4 . M is the bound state mass. m 1 and m 2 are the masses of the heavy constituent and the light constituent, respectively. l is the orbital angular momentum and n r is the radial quantum number. β x and c 0 x are fitted. m 1 , m 2 and C ′ are input parameters. These two formulas consider both of the masses of heavy constituent and light constituent. We find that the heavy-light diquarks, the heavy-light mesons, the heavy-light baryons and the heavy-light tetraquarks satisfy these two formulas. When applying the first formula, the heavy-light systems satisfy the universal description irrespective of both of the masses of the light constituents and the heavy constituent. When using the second relation, the heavy-light systems satisfy the universal description irrespective of the mass of the heavy constituent. The fitted slopes differ distinctively for the heavy-light mesons, baryons and tetraquarks, respectively. When employing the first relation, the average values of c f n r ( c fl ) are 1.026, 0.794 and 0.553 (1.026, 0.749 and 0.579) for the heavy-light mesons, the heavy-light baryons and the heavy-light tetraquarks, respectively. Upon application of the second relation, the mean values of c f n r ( c fl ) are 1.108, 0.896 and 0.647 (1.114, 0.855 and 0.676) for the heavy-light mesons, the heavy-light baryons and the heavy-light tetraquarks, respectively. Moreover, the fitted results show that the Regge trajectories for the heavy-light systems are concave downwards in the (M 2 , n r) and (M 2 , l) planes. [ABSTRACT FROM AUTHOR]