Search

Chiral dynamics is investigated using the chiral confining Lagrangian (CCL), previously derived from QCD with confinement interaction. Based on the calculations of the quark condensate, which is defined entirely by confinement in the zero quark mass limit, one can assert that chiral symmetry breaking is predetermined by confinement. It is shown that CCL retains all basic relations of the standard chiral theory but enables one to include quark degrees of freedom in the CCL. The expansion of the CCL provides the Gell–Mann–Oakes–Renner (GMOR) relations and the masses and decay constants of all chiral mesons, including η , η ′ . For the latter, one needs to define a nonchiral component due to confinement, while the orthogonality condition defines the wave functions and the eigenvalues. The resulting masses and decay constants of all chiral mesons are obtained in good agreement with the experimental and lattice data. [ABSTRACT FROM AUTHOR]

The effects of parity violation in the interaction of relativistic polarized protons with and nuclei are discussed. Within the Glauber approach, estimates are obtained for P-odd asymmetries in the total and elastic scattering cross sections, the dissociation cross section, and in the inelastic scattering cross section with meson production. Our calculations show that asymmetry should be most noticeable in the elastic cross section and in the dissociation cross section. [ABSTRACT FROM AUTHOR]

In the QCD sum rules for the tetraquark (molecular) states, the higher-dimensional vacuum condensates play an important role in extracting the tetraquark masses. We carry out the operator product expansion up to the vacuum condensates of dimension-10 and observe that the vacuum condensates of dimensions 6, 8 and 10 have the same expressions but opposite signs for the C γ 5 ⊗ γ μ C -type and C ⊗ γ μ C -type four-quark currents, which make their influences distinguishable, and they are excellent channels to examine the vacuum saturation approximation. We introduce a parameter κ to parametrize the derivation from the vacuum saturation or factorization approximation, and choose two sets of parameters to examine the influences on the predicted tetraquark masses, which can be confronted to the experimental data in the future. In all the channels, smaller value of the κ leads to better convergent behavior in the operator product expansion, which favors the vacuum saturation approximation. [ABSTRACT FROM AUTHOR]

Hulthen plus Hellmann potentials are adopted as the quark–antiquark interaction potential for studying the thermodynamic properties and the mass spectra of heavy mesons. The potential was rendered temperature dependent by replacing the screening parameter with Debye mass. We solved the radial Schrödinger equation analytically using the Nikiforov–Uvarov method. The energy eigenvalues and corresponding wave function in terms of Laguerre polynomials were obtained. The present results are applied for calculating the mass of heavy mesons, such as charmonium --> c c ¯ --> and bottomonium --> b b ¯ --> , and thermodynamic properties, such as the mean energy, the specific heat, the free energy, and the entropy. Four special cases were considered when these potential parameters were set to zero, resulting in Hellmann potential, Yukawa potential, Coulomb potential, and Hulthen potential, respectively. The present potential provides satisfying results in comparison with experimental data and the work of other researchers. [ABSTRACT FROM AUTHOR]

Hadron spectroscopy provides a way to understand the dynamics of the strong interaction. For light hadron systems, only phenomenological models or lattice quantum chromodynamics (QCD) are applicable, because of the failure of perturbation expansions for QCD at low energy. Experimental data on light hadron spectroscopy are therefore crucial to provide necessary constraints on various theoretical models. Light meson spectroscopy has been studied using charmonium decays with the Beijing Spectrometer Experiment (BES) at the Beijing Electron-Positron Collider, operating at 2.0–4.6 GeV center-of-mass energy, for nearly three decades. Charmonium data with unprecedented statistics and well-defined initial and final states provide BESIII with unique opportunities to search for glueballs, hybrids and multi-quark states, as well as perform systematic studies of the properties of conventional light mesons. In this article, we review BESIII results that address these issues. [ABSTRACT FROM AUTHOR]

A comprehensive review of weak decays of charmed hadrons (D 0/ +, |$D^+_s$| and |$\Lambda ^+_c$|⁠) based on analyses of the threshold data from e + e − annihilation in the BESIII experiment is presented. Current experimental challenges and successes in understanding decays of the charmed hadrons are discussed. Precise calibrations of quantum chromodynamics and tests of the standard model are provided by measurements of purely leptonic and semi-leptonic decays of charmed hadrons, and lepton universality is probed in purely leptonic decays of charmed mesons to three generations of leptons. Quantum correlations in threshold data samples provide access to strong phases in the neutral D meson decays and probe the decay dynamics of the charmed Λ c baryon. Charm physics studies with near-threshold production of charmed particle pairs are unique to BESIII, and provide many important opportunities and challenges. [ABSTRACT FROM AUTHOR]

Studies of light meson decays are important tools to perform precision tests of the effective field theories, determine transition form factors and test fundamental symmetries. With very high statistics data samples, the Beijing Spectrometer III (BESIII) experiment provides a unique laboratory for light meson studies and is contributing significantly to a variety of these investigations. A brief review of recent progress in light meson decay studied at the BESIII experiment, including detailed studies of common decay dynamics, searches for rare/forbidden decays and new particles, is presented. Finally, together with descriptions of different experimental techniques, prospects for future studies of light mesons are discussed in some detail. [ABSTRACT FROM AUTHOR]

We present a field-programmable gate array (FPGA)-based technique for the on-line identification of highly ionizing particles in a liquid xenon (LXe) detector. The method was developed and successfully exploited to select $\alpha $ particles emitted by 241Am sources submerged in LXe in an overwhelming, mostly beam-related, $\gamma $ -ray background. After revising the main features of xenon and other liquid noble gases as ultra-violet (UV) scintillating media, we describe the algorithm idea and its firmware implementation. We then present the results in terms of efficiency and background suppression for the real-time $\alpha $ -particle tagging and the limits of the MEG trigger configuration. Finally, we show that in MEG II we are going to overcome the main issues and further improve the performances. [ABSTRACT FROM AUTHOR]

We analyze mesons in constant magnetic fields (B) within a non-relativistic constituent quark model. Our quark model contains a harmonic oscillator type confining potential, and we perturbatively treat short range correlations to account for the spin-flavor energy splittings. We study both neutral and charged mesons taking into account the internal quark dynamics. The neutral states are labelled by two-dimensional momenta for magnetic translations, while the charged states by two discrete indices related to angular momenta. For B ≪ Λ QCD 2 ( Λ QCD ∼ 200 MeV: the QCD scale), the analyses proceed as in usual quark models, while special precautions are needed for strong fields, B ∼ Λ QCD 2 , especially when we treat short range correlations such as the Fermi-Breit-Pauli interactions. We compute the energy spectra of mesons up to energies of ∼ 2.5 GeV and use them to construct the meson resonance gas. Within the assumption that the constituent quark masses are insensitive to magnetic fields, the phase space enhancement for mesons significantly increases the entropy, assisting a transition from a hadron gas to a quark gluon plasma. We confront our results with the lattice data, finding reasonable agreement for the low-lying spectra and the entropy density at low temperature less than ∼ 100 MeV, but our results at higher energy scale suffer from artifacts of our confining potential and non-relativistic treatments. [ABSTRACT FROM AUTHOR]

We explore the system size dependence of heavy-quark-QGP interaction by studying the heavy flavor meson suppression and elliptic flow in Pb–Pb, Xe–Xe, Ar–Ar and O–O collisions at the LHC. The space-time evolution of the QGP is simulated using a (3 + 1) -dimensional viscous hydrodynamic model, while the heavy-quark-QGP interaction is described by an improved Langevin approach that includes both collisional and radiative energy loss inside a thermal medium. Within this framework, we provides a reasonable description of the D meson suppression and flow coefficients in Pb–Pb collisions, as well as predictions for both D and B meson observables in other collision systems yet to be measured. We find a clear hierarchy for the heavy meson suppression with respect to the size of the colliding nuclei, while their elliptic flow coefficient relies on both the system size and the geometric anisotropy of the QGP. Sizable suppression and flow are predicted for both D and B mesons in O–O collisions, which serve as a crucial bridge of jet quenching between large and small collision systems. Scaling behaviors between different collision systems are shown for heavy meson suppression factor and the bulk-eccentricity-rescaled heavy meson elliptic flow as functions of the number of participant nucleons in heavy-ion collisions. [ABSTRACT FROM AUTHOR]

We perform a study of the D s + → a 0 (980) (f 0 (980)) e + ν e reactions investigating the different sources of isospin violation which make the production of the a 0 (980) possible. We find that loops involving kaons in the production mechanism provide a source of isospin violation since they do not cancel due to the different mass of charged and neutral kaons, but we also find that the main source comes from the breaking of isospin in the meson-meson transition T matrices, which contain information on the nature of the low lying scalar mesons. The reaction is thus very sensitive to the nature of the a 0 (980) and f 0 (980) resonances. Our results are consistent with the present upper bound for a 0 (980) production and only a factor three smaller, indicating that future runs with more statistics should find actual numbers for this reaction from where we can learn more about the origin of the scalar resonances and their nature. [ABSTRACT FROM AUTHOR]

A flavour-tagged time-dependent angular analysis of B s 0 → J / ψ ϕ decays is presented where the J / ψ meson is reconstructed through its decay to an e + e - pair. The analysis uses a sample of pp collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and 8 \,Te V , corresponding to an integrated luminosity of 3 \,fb - 1 . The C P -violating phase and lifetime parameters of the B s 0 system are measured to be ϕ s = 0.00 ± 0.28 ± 0.07 \,rad , Δ Γ s = 0.115 ± 0.045 ± 0.011 \,ps - 1 and Γ s = 0.608 ± 0.018 ± 0.012 \,ps - 1 where the first uncertainty is statistical and the second systematic. This is the first time that C P -violating parameters are measured in the B s 0 → J / ψ ϕ decay with an e + e - pair in the final state. The results are consistent with previous measurements in other channels and with the Standard Model predictions. [ABSTRACT FROM AUTHOR]

We argue that high-quality data on the reaction e + e - → π + π - η will allow one to determine the doubly-virtual form factor η → γ ∗ γ ∗ in a model-independent way with controlled accuracy. This is an important step towards a reliable evaluation of the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon. When analyzing the existing data for e + e - → π + π - η for total energies squared k 2 > 1 GeV 2 , we demonstrate that the effect of the a 2 meson provides a natural breaking mechanism for the commonly employed factorization ansatz in the doubly-virtual form factor F η γ ∗ γ ∗ (q 2 , k 2) . However, better data are needed to draw firm conclusions. [ABSTRACT FROM AUTHOR]

In this study, the bound state solutions of the Dirac equation (DE) have been determined with the generalized Cornell potential model (GCPM) under the condition of spin symmetry. The GCPM includes the Cornell potential plus a combination of the harmonic and inversely quadratic potentials. In the framework of the Nikiforov–Uvarov (NU) method, the relativistic and nonrelativistic energy eigenvalues for the GCPM have been obtained. The energies spectra of the Kratzer potential (KP) and the modified Kratzer potential (MKP) have been derived as particular cases of the GCPM. The present results have been applied to some diatomic molecules (DMs) as well as heavy and heavy-light mesons. The energy eigenvalues of the KP and MKP have been computed for several DMs, and they are fully consistent with the results found in the literature. In addition, the energy eigenvalues of the GCPM have been employed for predicting the spin-averaged mass spectra of heavy and heavy-light mesons. One can note that our predictions are in close agreement with the experimental data as well as enhanced compared to the recent studies. [ABSTRACT FROM AUTHOR]

With updated experimental data and improved theoretical calculations, several significant deviations are being observed between the Standard Model predictions and the experimental measurements of the branching ratios of B ¯ s 0 → D s ∗ + L − decays, where L is a light meson from the set {π, ρ, K(∗)}. Especially for the two channels B ¯ 0 → D + K − and B ¯ s 0 → D s + π − , both of which are free of the weak annihilation contribution, the deviations observed can even reach 4–5σ. Here we exploit possible new-physics effects in these class-I non-leptonic B-meson decays within the framework of QCD factorization. Firstly, we perform a model-independent analysis of the effects from twenty linearly independent four-quark operators that can contribute, either directly or through operator mixing, to the quark-level b → c u ¯ d s transitions. It is found that, under the combined constraints from the current experimental data, the deviations observed could be well explained at the 1σ level by the new-physics four-quark operators with γμ(1 − γ5) ⨂ γμ(1 − γ5) structure, and also at the 2σ level by the operators with (1 + γ5) ⨂ (1 − γ5) and (1 + γ5) ⨂ (1 + γ5) structures. However, the new-physics four-quark operators with other Dirac structures fail to provide a consistent interpretation, even at the 2σ level. Then, as two specific examples of model-dependent considerations, we discuss the case where the new-physics four-quark operators are generated by either a colorless charged gauge boson or a colorless charged scalar, with their masses fixed both at the 1 TeV. Constraints on the effective coefficients describing the couplings of these mediators to the relevant quarks are obtained by fitting to the current experimental data. [ABSTRACT FROM AUTHOR]

Measurements of elliptic (v2) and triangular (v3) flow coefficients of π±, K±, p+ p ¯ , K S 0 , and Λ+ Λ ¯ obtained with the scalar product method in Xe-Xe collisions at s NN = 5.44 TeV are presented. The results are obtained in the rapidity range |y| < 0.5 and reported as a function of transverse momentum, pT, for several collision centrality classes. The flow coefficients exhibit a particle mass dependence for pT< 3 GeV/c, while a grouping according to particle type (i.e., meson and baryon) is found at intermediate transverse momenta (3 < pT< 8 GeV/c). The magnitude of the baryon v2 is larger than that of mesons up to pT = 6 GeV/c. The centrality dependence of the shape evolution of the pT-differential v2 is studied for the various hadron species. The v2 coefficients of π±, K±, and p+ p ¯ are reproduced by MUSIC hydrodynamic calculations coupled to a hadronic cascade model (UrQMD) for pT< 1 GeV/c. A comparison with vn measurements in the corresponding centrality intervals in Pb-Pb collisions at s NN = 5.02 TeV yields an enhanced v2 in central collisions and diminished value in semicentral collisions. [ABSTRACT FROM AUTHOR]

We study two- and three-meson systems composed either of pions or kaons at maximal isospin using Monte Carlo simulations of lattice QCD. Utilizing the stochastic LapH method, we are able to determine hundreds of two- and three-particle energy levels, in nine different momentum frames, with high precision. We fit these levels using the relativistic finite-volume formalism based on a generic effective field theory in order to determine the parameters of the two- and three-particle K-matrices. We find that the statistical precision of our spectra is sufficient to probe not only the dominant s-wave interactions, but also those in d waves. In particular, we determine for the first time a term in the three-particle K-matrix that contains two-particle d waves. We use three Nf = 2 + 1 CLS ensembles with pion masses of 200, 280, and 340 MeV. This allows us to study the chiral dependence of the scattering observables, and compare to the expectations of chiral perturbation theory. [ABSTRACT FROM AUTHOR]

Model-independent description of nonleptonic decays of charmed mesons is a challenging task due to large nonperturbative effects of strong interactions on the transition amplitudes. We discuss the equivalence of two different flavor-SU(3)-based descriptions of Cabibbo-favored non-leptonic decays of charmed mesons to two-pseudoscalars final states including the η and η′ mesons. [ABSTRACT FROM AUTHOR]

In this article, we utilise the non-relativistic potential model to calculate the mass-spectra of all bottom [ b b ] [ b ¯ b ¯ ] and heavy-light bottom [ b q ] [ b ¯ q ¯ ] (q = u,d) tetraquark states in diquark–antidiquark approximation. The four-body problem is reduced into two body problem by numerically solving the S c h r o ¨ d i n g e r equation using a Cornell-inspired potential along with relativistic correction term. The splitting structure of the tetraquark spectrum is described using spin-dependent terms (spin-spin, spin-orbit, and tensor). We have successfully calculated and predicted the masses of bottom mesons, diquarks and tetraquarks. The masses of S and P-wave tetraquark states [ b b ] [ b ¯ b ¯ ] and [ b q ] [ b ¯ q ¯ ], respectively, are found to be between 18.7–19.4 GeV and 10.4–11.3 GeV, in which the masses of S-wave [ b b ] [ b ¯ b ¯ ] states are less than the 2 η b , η b Υ , and 2 Υ threshold. Additionally, we have investigated the Z b (10610) and Z b (10650) states in the current model and found that they are 150 MeV below the B B ∗ and B ∗ B ∗ thresholds. [ABSTRACT FROM AUTHOR]

We study, by optical spectroscopy, the properties of high-current electric arcs that form between opening Cu contacts. The presence of a current that increases linearly with a rate of about 14 kA/ms leads to the separation of the contacts and to the formation of a bridge of molten metal that eventually ruptures. We show that after the molten bridge rupture, it takes about 40 $\mu \text{s}$ for the initial arc to be at local thermal equilibrium. This long thermalization time suggests that the plasma density during that time range is low, which we confirm using a simple modeling of the energy transfer between electrons and heavy particles. We explain these low densities by the fact that the molten bridge rupture leads to the formation of a shock wave. The initial dense plasma rapidly expands and a region with a pressure below the background pressure forms between the two contacts, leading to low plasma densities and long thermalization times. [ABSTRACT FROM AUTHOR]

Despite the undeniable success of the standard model of particle physics (SM), there are some phenomena that the SM cannot explain. These phenomena indicate that the SM has to be modified. One of the possible ways to extend the SM is to introduce heavy neutral leptons (HNLs). To search for HNLs in intensity Frontier experiments, one has to consider HNL production both in two-body and three-body decays of some mesons. We verified the possibility of using the parton level PYTHIA default matrix elements (without the form-factor formalism) to calculate HNL production in three-body semileptonic decays of B and D mesons in the experimentally interesting mass range of the produced HNLs. We conclude that this approach is quite suitable for the estimation of the sensitivity region for HNLs in the intensity Frontier experiments, provided one uses suitable parton level PYTHIA default matrix elements. Our study was driven by the usage of such an approximation by the SHiP collaboration. We conclude that in this case the parton level PYTHIA default matrix elements could have been chosen more appropriately. [ABSTRACT FROM AUTHOR]

We study the problem of π production in heavy-ion collisions in the context of the isospin-dependent Boltzmann–Uehling–Uhlenbeck transport model. We generated nucleon densities using two different models, the Skyrme–Hartree–Fock (SHF) model and the configuration interaction shell model (SM). Indeed, inter-nucleon correlations are explicitly taken into account in SM, while they are averaged in the SHF model. As an application of our theoretical frameworks, we calculated the π − and π + yields in collisions of nuclei with A = 30–40 nucleons. We used different harmonic oscillator lengths b HO to generate the harmonic oscillator basis for SM in order to study both theoretical and experimental cases. It is found that the SM framework with b HO = 2.5 fm and SHF can be distinguished by the yield of π mesons, in this case the density distribution calculated by the SM produces more π in the collision. In comparison, SM with b HO = 2.0 fm is distinguished from SHF by the double π −/ π + ratios with different large impact parameters, from which one can find that the double π −/ π + ratios of SM change smoother and are less than those of SHF. [ABSTRACT FROM AUTHOR]

The mass spectra for the heavy-light (c q ¯) ; q = u or d charmed mesons are computed based on a relativistic framework. The low-lying 1P states are found to be in an excellent agreement with the PDG reported values. Using the computed mass spectra and following effective Lagrangian approach based on heavy quark and chiral symmetry, the OZI allowed two body strong decays are computed. The computed decay rates, ratios and branching fractions allow us to identify the proper spin-parity assignments of the newly observed charm states. Accordingly, we could identify D J (2560) as 2 1 S 0 , D J ∗ (2680) as 2 3 S 1 , D J (2740) as 1 3 D 2 , D J ∗ (2760) as 1 3 D 3 , D J ∗ (3000) as 2 3 P 0 , D J (3000) as 2 1 P 1 and D 2 ∗ (3000) as 1 3 F 2 open charm states. The effective coupling constants, g T , g H ~ , g Y , g S ~ and g Z extracted from the present study are found to be in accordance with the reported values. These coupling constants would be useful in further investigations. We found D ∗ + π - as a favorable channel for the experimental search of the missing 1 1 F 3 state. [ABSTRACT FROM AUTHOR]

In this paper, the differential cross section of charmed mesons production ( D s ± , D 0 , D ∗ and D ∗ ± and D ± ) are computed as a function of transverse momentum p T and the total cross sections. The hadronization mechanism is considered via a fragmentation process of a c heavy quark to a light-heavy meson according to Suzuki's model. The two-cutoff phase-space slicing method has been applied to calculate the phase-space integral of two- and three-body subprocess cross sections and fragmentation function (FF) at next-to-leading order (NLO) accuracy. By using Monte Carlo (MC) techniques, we try to properly estimate the ratio of neutral to charged D-meson production R u / d and the strangeness-suppression factor γ s . Our numerical results show that the NLO corrections of the FF have significant effect on D-mesons production and enhance the cross section ratio at NLO respect to leading order (LO) about 50 % . A comparison indicates that our cross section results are in agreement (within uncertainties) with available data from ATLAS and ALICE and theoretical predictions of the fixed-order next-to-leading-logarithm (FONLL) approach and NLO parton-shower MC simulation (MC@NLO) in high-energy proton–proton (pp) collisions at s = 7 T e V . [ABSTRACT FROM AUTHOR]

Recently, LHCb Collaboration announced the discovery of radial excitations of D s and B s mesons. In present work, we calculate the most promising strong and electromagnetic decay widths of radially excited D s (2 S) and B s (2 S) mesons within the light cone QCD sum rules method. [ABSTRACT FROM AUTHOR]

Two-particle Azimuthal correlations are measured with the ALICE apparatus in pp collisions at s = 13 TeV to explore strangeness- and multiplicity-related effects in the fragmentation of jets and the transition regime between bulk and hard production, probed with the condition that a strange meson ( K S 0 ) or baryon (Λ ) with transverse momentum p T > 3 GeV/ c is produced. Azimuthal correlations between kaons or Λ hyperons with other hadrons are presented at midrapidity for a broad range of the trigger ( 3 < p T trigg < 20 GeV/ c ) and associated particle p T (1 GeV/ c < p T assoc < p T trigg ), for minimum-bias events and as a function of the event multiplicity. The near- and away-side peak yields are compared for the case of either K S 0 or Λ ( Λ ¯ ) being the trigger particle with that of inclusive hadrons (a sample dominated by pions). In addition, the measurements are compared with predictions from PYTHIA 8 and EPOS LHC event generators. [ABSTRACT FROM AUTHOR]

We consider the fidelity of the vector meson dominance (VMD) assumption as an instrument for relating the electromagnetic vector-meson production reaction e + p → e ′ + V + p to the purely hadronic process V + p → V + p . Analyses of the photon vacuum polarisation and the photon-quark vertex reveal that such a VMD Ansatz might be reasonable for light vector-mesons. However, when the vector-mesons are described by momentum-dependent bound-state amplitudes, VMD fails for heavy vector-mesons: it cannot be used reliably to estimate either a photon-to-vector-meson transition strength or the momentum dependence of those integrands that would arise in calculations of the different reaction amplitudes. Consequently, for processes involving heavy mesons, the veracity of both cross-section estimates and conclusions based on the VMD assumption should be reviewed, e.g., those relating to hidden-charm pentaquark production and the origin of the proton mass. [ABSTRACT FROM AUTHOR]

Laser-induced nuclear reactions in ultra-dense hydrogen H(0) produce mesons with both relatively low kinetic energy and with high kinetic energy. The kaons have up to 100 MeV of kinetic energy, thus a velocity of 0.55 c. Each laser pulse of >0.1 J of energy and length of 5 ns produces 1013 mesons. The operation of the meson generator is here demonstrated by measuring all decay times for mesons in the ns range after induction by a pulsed laser. These decay times are the unique fingerprints of the mesons, and they also produce the kinetic energy of the mesons created from their time-dilated decay. The charged pion decay time at rest from this generator is measured to be 25.92 ± 0.04 ns (standard fit error), in reasonable agreement with the tabulated results of 26.033 ns. A similar accuracy is found for the other mesons as for the charged kaons, with 96 MeV of kinetic energy, at 14.81 ± 0.05 ns. The same general behaviour is found with both deuterium and normal hydrogen forming the ultra-dense phase H(0) on the laser target. This meson generator gives intense meson showers useful for many types of particle physics experiments at a small fraction of the cost of using particle accelerators. A particle accelerator would need an energy of at least 1021 eV to produce a similar shower of 1013 mesons. Thus, the described generator is among the most intense meson sources that exist. Other important applications include nuclear energy generation and particle (pion) radiation for cancer treatment.

The effect of the interaction of mesons in the final state is additionally considered within the description of τ → π η (η ′) ν τ decays. This interaction is taken into account at the level of production of intermediate pions. One of them, in turn, might be transited into η or η ′ mesons. Our results do not exceed the experimentally established branching fractions, and they are in agreement with the results of other theoretical studies. [ABSTRACT FROM AUTHOR]

In this paper, we first derive two QCD sum rules QCDSR I and QCDSR II which are, respectively, used to extract observable quantities of the ground states and the first radially excited states of the D-wave vector ρ and ϕ mesons. In our calculations, we consider the contributions of vacuum condensates up to dimension-7 in the operator product expansion. The predicted masses for 1 3 D 1 ρ meson and 2 3 D 1 ϕ meson are consistent well with the experimental data of ρ (1 7 0 0) and ϕ (2 1 7 0), respectively. Besides, our analysis indicates that it is reliable to assign the recent reported Y (2 0 4 0) state as the 2 3 D 1 ρ meson. Finally, we obtain the decay constants of these states with QCDSR I and QCDSR II. These predictions are helpful not only to reveal the structure of the newly observed Y (2 0 4 0) state, but also to establish ϕ meson and ρ meson families. [ABSTRACT FROM AUTHOR]

In the system of a pair of quantum-entangled neutral kaons from meson decays, when one kaon collapses into the K S state, the other will collapse instantaneously into the K L state, due to entanglement and nonlocality. However, if the alternative hypothesis is correct and there is a time window during which one kaon is unaware that the other has decayed, some quantum mechanically prohibited K S K S decays may occur. We calculate the branching ratios of K S K S in vector meson decays under locality hypothesis and compare them with experimental results. We show that the branching ratio of J / ψ → K S K S under locality assumption is already excluded by the BESIII experimental upper limit. Additional experimental results are proposed to perform this test in the future. [ABSTRACT FROM AUTHOR]

In this paper, lattice simulations are used to propose a potential model for gluonic excited Σ-u states of bottomonium meson. This proposed model is used to calculate radial wave functions, masses and radii of Σ-u bottomonium hybrid mesons. Here, gluonic field between a quark and an antiquark is treated as in the Born-Oppenheimer expansion, and Schr o¨ dinger equation is numerically solved employing shooting method. Results of calculated masses for Σ-u state are in quite good agreement with the lattice. [ABSTRACT FROM AUTHOR]

The topology of closed manifolds forces interacting charges to appear in pairs. We take advantage of this property in the setting of the conformal boundary of AdS5 spacetime, topologically equivalent to the closed manifold S1× S3, by considering the coupling of two massless opposite charges on it. Taking the interaction potential as the analog of Coulomb interaction (derived from a fundamental solution of the S3 Laplace-Beltrami operator), a conformal S1× S3 metric deformation is proposed, such that free motion on the deformed metric is equivalent to motion on the round metric in the presence of the interaction potential. We give explicit expressions for the generators of the conformal algebra in the representation induced by the metric deformation. By identifying the charge as the color degree of freedom in QCD, and the two charges system as a quark-anti-quark system, we argue that the associated conformal wave operator equation could provide a realistic quantum mechanical description of the simplest QCD system, the mesons. Finally, we discuss the possibility of employing the compactification radius, R, as an- other scale along ΛQCD, by means of which, upon reparametrizing Q2c2 as (Q2c2+ħ2c2/R2), a perturbative treatment of processes in the infrared could be approached. [ABSTRACT FROM AUTHOR]

We propose a systematic theoretical framework for the topological amplitudes of the heavy meson decays and their SU(N) decomposition. In the framework, the topologies are expressed in invariant tensors and classified into tree- and penguin-operator-induced diagrams according to which four-quark operators, tree or penguin, being inserted into their effective weak vertexes. The number of possible topologies contributing to one type of decay can be counted by permutations and combinations. The Wigner-Eckhart theorem ensures the topological amplitudes under flavor symmetry are the same for different decay channels. By decomposing the four-quark operators into irreducible representations of SU(N) group, one can get the SU(N) irreducible amplitudes. Taking the D → PP decay (P denoting a pseudoscalar meson) with SU(3)F symmetry as an example, we present our framework in detail. The linear correlation of topologies in the SU(3)F limit is clarified in group theory. It is found there are only nine independent topologies in all tree- and penguin-operator-induced diagrams contributing to the D → PP decays in the Standard Model. If a large quark-loop diagram, named TLP, is assumed, the large ∆ACP and the very different D0→ K+K− and D0→ π+π− branching fractions can be explained with a normal U-spin breaking. Moreover, our framework provides a simple way to analyze the SU(N) breaking effects. The linear SU(3)F breaking and the high order U-spin breaking in charm decays are re-investigated in our framework, which are consistent with literature. Analogous to the degeneracy and splitting of energy levels, we propose the concepts of degeneracy and splitting of topologies to describe the flavor symmetry breaking effects in decay. As applications, we analyze the strange-less D decays in SU(3)F symmetry breaking into Isospin symmetry and the charm-less B decays in SU(4)F symmetry breaking into SU(3)F symmetry. [ABSTRACT FROM AUTHOR]

Nowadays High Energy Physics experiments can accumulate unprecedented statistics of heavy flavour decays that allows to apply new methods, based on the study of very rare phenomena, which used to be just desperate. In this paper we propose a new method to measure composition of K0- K ¯ 0, produced in a decay of heavy hadrons. This composition contains important information, in particular about weak and strong phases between amplitudes of the produced K0 and K ¯ 0. We consider possibility to measure these parameters with time-dependent K0 → π+π− analysis. Due to C P -violation in kaon mixing time-dependent decay rates of K0 and K ¯ 0 differ, and the initial amplitudes revealed in the CP-violating decay pattern. We perform phenomenological study of K0 decay evolution initially produced as a combination a K 0 t + b K ¯ 0 t , where a and b, complex amplitudes, could also be dependent on decay time of heavy mother particle. In particular we consider cases of charmed hadrons decays: D+ → K0π+, D s + → K0K+, Λ → pK0 and with some assumptions D0 → K0π0. This can be used to test the sum rule for charmed mesons and to obtain input for the full constraint of the two body amplitudes of D-mesons. [ABSTRACT FROM AUTHOR]

We study local quark-hadron duality and its violation for the D 0 − D ¯ 0 , B d 0 − B ¯ d 0 and B s 0 − B ¯ s 0 mixings in the 't Hooft model, offering a laboratory to test QCD in two-dimensional spacetime together with the large-Nc limit. With the 't Hooft equation being numerically solved, the width difference is calculated as an exclusive sum over two-body decays. The obtained rate is compared to inclusive one that arises from four-quark operators to check the validity of the heavy quark expansion (HQE). In view of the observation in four-dimensions that the HQE prediction for the width difference in the D 0 − D ¯ 0 mixing is four orders of magnitude smaller than the experimental data, in this work we investigate duality violation in the presence of the GIM mechanism. We show that the order of magnitude of the observable in the D 0 − D ¯ 0 mixing is enhanced in the exclusive analysis relative to the inclusive counterpart, when the 4D-like phase space function is used for the inclusive analysis. By contrast, it is shown that for the B d 0 − B ¯ d 0 and B s 0 − B ¯ s 0 mixings, small yet non-negligible corrections to the inclusive result emerge, which are still consistent with what is currently indicated in four-dimensions. [ABSTRACT FROM AUTHOR]

The on-shell matrix elements, or couplings g H H ∗ H 1 γ , describing the B D q ∗ → B(D)qγ and B1q → Bqγ (q = u, d, s) radiative decays, are determined from light-cone sum rules at next-to-leading order for the first time. Two different interpolating operators are used for the vector meson, providing additional robustness to our results. For the D*-meson, where some rates are experimentally known, agreement is found. The couplings are of additional interest as they govern the lowest pole residue in the B(D) → γ form factors which in turn are connected to QED-corrections in leptonic decays B(D) → ℓ ν ¯ . Since the couplings and residues are related by the decay constants f H ∗ H 1 and f H ∗ H 1 T , we determine them at next-leading order as a by-product. The quantities f H ∗ T f H 1 T have not previously been subjected to a QCD sum rule determination. All results are compared with the existing experimental and theoretical literature. [ABSTRACT FROM AUTHOR]

The 𝜙4 double-well theory admits a kink solution, whose rich phenomenology is strongly affected by the existence of a single bound excitation called the shape mode. We find that the leading quantum correction to the energy needed to excite the shape mode is −0.115567λ/M in terms of the coupling λ/4 and the meson mass M evaluated at the minimum of the potential. On the other hand, the correction to the continuum threshold is −0.433λ/M. A naive extrapolation to finite coupling then suggests that the shape mode melts into the continuum at the modest coupling of λ/4 ∼ 0.106M2, where the ℤ2 symmetry is still broken. [ABSTRACT FROM AUTHOR]

We propose a scheme of lattice twisted-mass fermion regularization which is particularly convenient for application to isospin breaking (IB) QCD and QED calculations, based in particular on the so called RM123 approach, in which the IB terms of the action are treated as a perturbation. The main, practical advantage of this scheme is that it allows the calculation of IB effects on some mesonic observables, like e.g. the π + - π 0 mass splitting, using lattice correlation functions in which the quark and antiquark fields in the meson are regularized with opposite values of the Wilson parameter r. These correlation functions are found to be affected by much smaller statistical fluctuations, with respect to the analogous functions in which quark and antiquark fields are regularized with the same value of r. Two numerical application of this scheme, that we call rotated twisted-mass, within pure QCD and QCD + QED respectively, are also provided for illustration. [ABSTRACT FROM AUTHOR]

We study the impact of the coupling of neutrinos with a new light neutral gauge boson, Z′, with a mass of less than 500 MeV in FASERν experiment. Scenarios in which a light gauge boson is coupled to neutrinos are motivated within numerous contexts which are designed to explain various anomalies in particle physics and cosmology. This interaction leads to a new decay mode for charged mesons to a light lepton plus neutrino and Z′, (M+ → l+νZ′), followed by the subsequent decay of Z′ into the pair of neutrino and anti-neutrino, (). FASERν, the Forward Search Experiment at the Large Hadron Collider, has the potential to detect collider neutrinos for the first time. In particular, the FASERν emulsion detector will provide the opportunity to detect τ-neutrinos and to measure their energies. Using this ability of FASERν emulsion detector, we investigate the potential of FASERν experiment and the proposed upgraded version of this experiment, FASER2ν, to constrain the coupling of a neutrino with the light gauge boson. [ABSTRACT FROM AUTHOR]

The topology of closed manifolds forces interacting charges to appear in pairs. We take advantage of this property in the setting of the conformal boundary of AdS5 spacetime, topologically equivalent to the closed manifold S1× S3, by considering the coupling of two massless opposite charges on it. Taking the interaction potential as the analog of Coulomb interaction (derived from a fundamental solution of the S3 Laplace-Beltrami operator), a conformal S1× S3 metric deformation is proposed, such that free motion on the deformed metric is equivalent to motion on the round metric in the presence of the interaction potential. We give explicit expressions for the generators of the conformal algebra in the representation induced by the metric deformation. By identifying the charge as the color degree of freedom in QCD, and the two charges system as a quark-anti-quark system, we argue that the associated conformal wave operator equation could provide a realistic quantum mechanical description of the simplest QCD system, the mesons. Finally, we discuss the possibility of employing the compactification radius, R, as an- other scale along ΛQCD, by means of which, upon reparametrizing Q2c2 as (Q2c2+ħ2c2/R2), a perturbative treatment of processes in the infrared could be approached. [ABSTRACT FROM AUTHOR]

In this paper, the mass spectra of mesons with one or two heavy quarks and their diquarks partners are estimated within a nonrelativistic framework by solving Schrödinger equation with an effective potential inspired by a symmetry preserving Poincaré covariant vector–vector contact interaction model of quantum chromodynamics. Matrix Numerov method is implemented for this purpose. In our survey of mesons with heavy quarks, we fix the model parameter to the masses of groundstates and then extend our calculations for radial excitations and diquarks. The potential model used in this work gives results which are in good agreement with experimental data and other theoretical calculations. [ABSTRACT FROM AUTHOR]

In a particle theory model whose most readily discovered new particle is the ∼ 1 TeV bilepton resonance in same-sign leptons, currently being sought at CERN's LHC, there exist three quarks , , which will be bound by QCD into baryons and mesons. We consider the decays of these additional baryons and mesons whose detailed experimental study will be beyond the reach of the 14 TeV CERN collider and accessible only at an O(100 TeV) collider. [ABSTRACT FROM AUTHOR]

The width of the decay has been calculated within the extended Nambu–Jona-Lasinio model including the final-state interaction of mesons. Both the contact term and the channel with the intermediate ground state and its first radial excitation have been taken into account. To describe the final-state interaction, a triangle diagram with three mesons has been considered. The cutoff parameter in the diverging integrals over the meson loop has been taken the same as in our preceding work to describe the decay, so no additional parameters are introduced. Satisfactory agreement with experimental data has been obtained. [ABSTRACT FROM AUTHOR]

In 2019, LHCb reported the first observation of direct CP violation in the charm sector. As of yet indirect CP violation has not been observed but measurements of this and mixing is essential to our understanding of the Standard Model. We report on the latest measurements of CP violation and mixing in charm mesons from LHCb and present prospects for future measurements. [ABSTRACT FROM AUTHOR]

The beauty hadron decays provide a unique laboratory to study charmonium and charmonium-like states, such as the χc1(3872) meson, other exotic states, and the tensor D-wave ψ2(3823) states. However, the nature of many exotic charmonium-like candidates is still unknown. The most recent LHCb results related to b-hadron decays to charmonium states and obtained using large data samples collected during the Run 1 and Run 2 periods are presented. This includes the most precise determination of the mass and width of the χc1(3872) state using the B+ → J/ψπ+π-K+ decays, observation of a resonant structure denoted as X(4740) in the J/ψφ mass spectrum from B0s → J/ψπ+π-K+K- decays and the precise measurement of the B0s meson mass. [ABSTRACT FROM AUTHOR]

The mass modifications of the open charm (D and D ∗ ) mesons, and their effects on the decay widths D ∗ → D π as well as of the charmonium state, Ψ (3 7 7 0) to open charm mesons (Ψ (3 7 7 0) → D D ̄), are investigated in the presence of strong magnetic fields. These are studied accounting for the mixing of the pseudoscalar (P) and vector (V) mesons (D − D ∗ , η c ′ − Ψ (3 7 7 0) mixings), with the mixing parameter, g P V of a phenomenological three-point (P V γ) vertex interaction determined from the observed radiative decay width of V → P γ. For charged D − D ∗ mixing, this parameter is dependent on the magnetic field, because of the Landau level contributions to the vacuum masses of these mesons. The masses of the charged D and D ∗ mesons modified due to P V mixing, in addition, have contributions from the lowest Landau levels in the presence of a strong magnetic field. The effects of the magnetic field on the decay widths are studied using a field theoretical model of composite hadrons with quark (and antiquark) constituents. The matrix elements for these decays are evaluated using the light quark–antiquark pair creation term of the free Dirac Hamiltonian for the constituent quark field, with explicit constructions for the charmonium state Ψ (3 7 7 0) , the open charm (D , D ̄ , D ∗ ) mesons and the pion states in terms of the constituent quark fields. The parameter for the charged D − D ∗ mixing is observed to increase appreciably with increase in the magnetic field. This leads to dominant modifications to their masses, and hence the decay widths of charged D ∗ → D π as well as Ψ (3 7 7 0) → D + D − at large values of the magnetic field. The modifications of the masses and decay widths of the open and hidden charm mesons in the presence of strong magnetic fields should have observable consequences on the production of the open charm (D and D ∗ ) mesons as well as of the charmonium states resulting from noncentral ultra-relativistic heavy ion collision experiments. [ABSTRACT FROM AUTHOR]

The isospin splitting of the in-medium N N → N Δ cross-sections in asymmetric nuclear medium is investigated in the framework of the one-boson exchange model by including δ and ρ mesons. Our results show that the medium correction factors R = σ N N → N Δ ∗ / σ N N → N Δ free have R p p → n Δ + + < R n n → p Δ − and R N N → N Δ + < R N N → N Δ 0 by using the without- δ sets. By including the δ meson, there appear the totally opposite results in the R for different channels, i.e., R p p → n Δ + + > R n n → p Δ − and R N N → N Δ + > R N N → N Δ 0 . [ABSTRACT FROM AUTHOR]

In this work we calculate the mass spectrum and decay constants of ground and excited states of heavy-light P-wave mesons such as 1++ and 1+−, with quark composition, c u ¯ , c s ¯ , b u ¯ , b s ¯ , and b c ¯ in the framework of a QCD motivated Bethe-Salpeter equation (BSE) by making use of the exact treatment of the spin structure (γ μ ⊗ γ μ) in the interaction kernel, In this 4 × 4 BSE framework, the coupled Salpeter equations for Q q ¯ are first solved for the confining part of interaction, and are shown to decouple under heavy-quark approximation. Then the one-gluon-exchange interaction is perturbatively incorporated, leading to their mass spectral equations. The analytic forms of wave functions obtained from these equations are then used for calculation of leptonic decay constants of ground and excited states of 1++, and 1+− as a test of these wave functions and the over all framework. [ABSTRACT FROM AUTHOR]

Ground-level cosmic ray muon detections have various potential applications in the predictions of space and Earth weather variations and muon tomography. However, in order to push its practical applications, a low-power, low-cost, high-accuracy, and portable ground-level cosmic ray muon detection system needs to be developed. In this article, we present a high time-resolution and low-power readout integrated circuit (ROIC) for portable ground-level cosmic ray muon detection. The ROIC comprises preamplifiers, comparators, encoding modules, a delay-locked loop (DLL), and a data transfer module. The preamplifiers amplify the weak signals produced by the muon detector. The comparators convert the amplified signals into digital signals. The encoding modules extract and store the time information of the input pulses produced by the comparator, and the data transfer module transmits them to a microcontroller unit (MCU). A pulse edge detecting method using DLL clocks is employed to improve the time-resolution and limit the power consumption of the ROIC. A 32-channel prototype of the ROIC was designed and fabricated in a 0.18- $\mu \text{m}$ mixed-signal CMOS process. The main chip size is 11.4 mm2. A one-channel double-layer plastic scintillator muon detector was used to test the performance of the ROIC. A time-resolution of 1.0 ns was achieved with a system clock of 50 MHz, and the ROIC power consumption was measured at 1.9 mW/channel. Compared with existing muon readout electronics systems, the system using the proposed ROIC achieves high time-resolution and accuracy, with low power consumption and a smaller size, making it suitable for portable real-time cosmic ray muon detection. [ABSTRACT FROM AUTHOR]