Search

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]

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]

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]

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 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 medium mass modification may lead to a squeezing effect. In the baryonic medium, the mass of D meson was expected to reduce and the in-medium masses of D + and D − may show a splitting effect, and the chemical potential of D meson may be not zero. We study the squeezing effect on the yield ratio D + ∕ D − with nonzero chemical potential. Due to the in-medium mass splitting, the squeezing effect on the momentum distributions of D + and D − are different. Without the squeezing effect, the yield ratio D + ∕ D − remains constant as the transverse momentum increases. The yield ratio D + ∕ D − is affected by the squeezing effect, resulting in a dependence on transverse momentum. An increase in transverse momentum leads to a decrease in the yield ratio, especially when there is a high chemical potential. Additionally, the in-medium mass splitting amplifies this phenomenon. The yield ratio D + ∕ D − with nonzero chemical potential approaches 1 when there is a large average in-medium mass reduction, which becomes more evident at higher transverse momentum. The study of the squeezing effect on the yield ratio D + ∕ D − with nonzero chemical potential may be meaningful for the CBM and PANDA experiments of the FAIR project at GSI. [ABSTRACT FROM AUTHOR]

The neutron skin of atomic nuclei impacts the structure of neutron-rich nuclei, but its accurate measurement is quite challenging. We present predictions for neutron skins and proton radii for light to medium mass nuclei by employing Covariant Density Functional Theory (CDFT) based on density-dependent meson-exchange interaction. Using our microscopic predictions, we find a linear correlation between the neutron skin and the isospin asymmetry. The calculations are also extended to find a linear relationship between proton and neutron radii of mirror nuclei. Using the charge symmetry property of nuclear forces, a correlation between the neutron skin of neutron-rich nuclei and difference between the proton radii of the corresponding mirror pair has also been investigated. The inclusion of ISB term is found to affect the mirror difference charge radii of 4 8 Ca- 4 8 Ni mirror pair. [ABSTRACT FROM AUTHOR]

The mass spectrum of heavy mesons using the Cornell potential is used for studying the quark–antiquark interaction. By appropriately modifying the potential parameters, the established potential models such as Kratzer's potential and the anharmonic one are applied in the Pekeris approximation. The Schrodinger equation for the Cornell potential setting is solved in this paper via the Nikiforov–Uvarov method. We acquire the confined-state energy spectrum to verify whether the outcome produced by this approach is accurate. The spectrum of energy formulation is used to determine the mass spectra of heavy quarkonium compounds, including charmonium and bottomonium. There is a comparison with various theoretical stances. The outcomes align well with both experimental data and other researchers' findings. [ABSTRACT FROM AUTHOR]

In this paper, we tentatively assign the Y (4 2 3 0) as the vector tetraquark state with a relative P-wave between the scalar diquark pair, and explore the three-body strong decays Y (4 2 3 0) → D ̄ ∗ − D ∗ 0 π + , D ̄ ∗ − D 0 π + , J ∕ ψ π + π − and J ∕ ψ K + K − with the light-cone QCD sum rules by assuming contact four-meson coupling constants. The resulting partial decay widths are too small to account for the experimental data, and we expect those decays take place through an intermediate meson. We can search for the intermediate states and precisely measure the branching fractions to diagnose the nature of the Y states. [ABSTRACT FROM AUTHOR]

The quark–antiquark potential is one of the basic ingredients of QCD-inspired potential models. This work will report the results of the masses and decay constants of heavy-flavor pseudo-scalar mesons within a QCD-based potential model having both inverse distance Coulomb and the linear confinement pieces. To that end, we use the inverse piece incorporating two-loop effects as suggested in V-scheme. Quantum mechanical perturbative methods: Dalgarno's method of perturbation theory and variationally improved perturbation theory are used for the investigation. We use the Coulombic piece as the parent which is allowed by both Dalgarno's perturbation theory and variationally improved perturbation theory. The results are compared with the latest updated theoretical predictions and PDG data. The sensitivity of the input parameters of the model has been discussed. [ABSTRACT FROM AUTHOR]

The mass spectra of light-heavy tetraquarks c q c ̄ q ̄ (q = u , d) are computed in a nonrelativistic diquark model with one-gluon exchange plus confining potential. In the diquark model, a c q c ̄ q ̄ state is regarded to be made of a light-heavy diquark (q c) and an antidiquark q ̄ c ̄ in antitriplet and triplet color configuration, respectively. The masses of charm mesons were calculated in order to fit the model parameters used to create the masses of tetraquarks and therefore enhance the model's reliability. The masses of (c q c ̄ q ̄) tetra-quark states are determined to be in the range of 3.8–4.7 GeV, which is consistent with the experimentally reported charmonium-like states. In particular, the Z c (3 9 0 0) , Z c (4 4 3 0) and ψ (4 6 6 0) tetraquarks, which have been seen experimentally, may all be described by our model. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the masses of the pseudoscalar (D ( D 0 , D + ), D ̄ ( D 0 ̄ , D − ) and vector open charm mesons ( D ∗ ( D ∗ 0 , D ∗ + ), D ̄ ∗ ( D ̄ ∗ 0 , D ∗ − ) as well as the pseudoscalar ( η c (1 S) , η c (2 S)) and the vector charmonium states (J ∕ ψ , ψ (2 S) , ψ (1 D)) in the asymmetric hot strange hadronic medium in the presence of strong magnetic fields. In the magnetized medium, the mass modification of open charm mesons due to their interactions with baryons and the scalar fields (σ , ζ , and δ) is investigated in a chiral effective model. Moreover, the charged pseudoscalar meson ( D ± ), as well as the longitudinal component of charged vector meson ( D ∗ ± ∥ ), experience additional positive mass modifications in the magnetic field due to Landau quantization. The effect of the modification of gluon condensates simulated by the medium change of dilaton field χ on the masses of the charmonia is also calculated in the chiral effective model. The contribution of masses of light quarks is also considered in the modification of gluon condensates. At high temperatures, the magnetically induced modifications of scalar fields significantly reduce the in-medium masses of mesons. The effects of magnetically induced spin mixing between the pseudoscalar and the corresponding vector mesons are incorporated in our study through a phenomenological effective Lagrangian interaction. The spin mixing result in a positive mass shift for the longitudinal component of the vector mesons and a negative mass shift for the pseudoscalar mesons in the presence of the magnetic field. From the obtained in-medium masses of charmonia and open charm mesons, we have also calculated the partial decay widths of ψ (1 D) to D D ̄ , using a light quark pair creation model, namely, the 3 P 0 model. [ABSTRACT FROM AUTHOR]

In this paper, we calculate the electromagnetic (EM) transition decay widths between two mesons containing different heavy quarks (c and b) for the process; B c ∗ → B c + γ , using the Bethe–Salpeter (BS) framework. The calculated results are found to be in a reasonable agreement with other theoretical models but the experimental data for this problem is not yet available. [ABSTRACT FROM AUTHOR]

The deformed Klein–Gordon equation has been solved in three-dimensional extended relativistic quantum mechanics (3D-ERQM) symmetries for the newly improved screened Kratzer potential (NISKP) model under the influence of the deformation space–space symmetries. The new relativistic energy eigenvalues were calculated using the parametric Bopp's shift method and standard perturbation theory in addition to the approximation scheme suggested by Greene and Aldrich for the inverse square terms. The new relativistic energy eigenvalues of (LiH, HCl, CO and H2) molecules under the NISKP model were shown to be sensitive to the atomic quantum numbers (j , l , s , m), mixed potential depths ( D e , r e ), the screening parameter's inverse (α , δ) , control parameter τ and non-commutativity parameters (Θ , β , ζ). In addition, we analyzed the non-relativistic energy values by applying the well-known transmission rules known in the literature. Furthermore, we studied many special cases useful to researchers in the framework of the new extended symmetries, such as the new screened cosine Kratzer potential, the new screened Kratzer potential (SKP), the new Kratzer potential, the new coshine Yukawa potential, the new coshine Yukawa potential, the new shifted improved SKP and the new shifted SKP. The study is further extended to calculate the mass spectra of mesons of the heavy quarkonium system such as charmonium c c ¯ , bottomonium b b ¯ , b ¯ c and light mesons c s ¯ and b s ¯ that have the quark and antiquark flavor within the framework of the NISKP model in 3D-ENRQM symmetries. [ABSTRACT FROM AUTHOR]

The NA61/SHINE collaboration measured the production of K S 0 in p + p interactions at two beam momenta: 80 and 158 GeV/c. The π + + π − decay of K S 0 (branching ratio of 69.2%) was measured via the invariant mass method. The rapidity and transverse momentum distributions of K S 0 are presented and compared to transport model predictions. The measured mean multiplicities of K S 0 mesons equal to 〈 K S 0 〉 = 0. 1 2 0 ± 0. 0 0 1 (stat.) ± 0. 0 0 5 (sys.) (80 GeV/c) and 〈 K S 0 〉 = 0. 1 6 2 ± 0. 0 0 1 (stat.) ± 0. 0 1 1 (sys.) (158 GeV/c) are compared with the available data in the energy range s N N = 3 –32 GeV. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the mass spectra and decay properties of B , B s and B c mesons using the relativistic potential model with confining potential V q (r) = 1 2 (1 + γ 0) (a 2 r + V 0). The calculated mass spectra of B , B s and B c accord to the findings of the experiments and other theoretical forecasts. Using the same parameters, we calculate possible radiative decay widths of V (n s) → P (n s) γ and P (n s) → V (n s) γ , n = 1 , 2 , 3 and weak leptonic decay constants of B , B s and B c mesons. Our results, in most cases, generally agree with experimental and other theoretical predictions. Finally, we also investigate mixing parameters x q , y q and χ q for B q 0 − B ¯ q 0 (q ϵ d , s) mesons, where our calculated values reasonably agree with the experiment. [ABSTRACT FROM AUTHOR]

In recent times, there have been several observations suggesting deviations from lepton universality in semileptonic decays of B mesons. These deviations have been noticed both in the neutral-current transitions (b → s l l) and charged-current transitions (b → c l ν ̄ l ). Motivated by these intriguing findings, we investigate the semileptonic decays involving the quark-level transitions of b → c l ν ̄ l . To explore the presence of new physics, we adopt a model-independent approach and analyze the processes Λ b → Λ c τ ν ̄ τ , B c + → η c τ + ν τ and B → D ∗ ∗ τ ν ̄ τ , where D ∗ ∗ = D 0 ∗ , D 1 ∗ , D 1 , D 2 ∗ represent the four lightest excited charm mesons. Considering a comprehensive effective Hamiltonian, we perform a global fit using various sets of new coefficients and incorporate measurements of R D , R D ∗ , R J ∕ ψ , P τ D ∗ , as well as the upper limit on the branching ratio of B c + → τ + ν τ . Subsequently, we examine the impact of constrained new couplings on the branching ratios, forward–backward asymmetry parameters, lepton nonuniversality (LNU) ratios, as well as lepton and hadron polarization asymmetries in these decay modes. [ABSTRACT FROM AUTHOR]

The Dirac equation (DE) plays an essential role in the relativistic quantum systems, which is reduced to a form similar to Schrödinger equation when a certain potential's type is selected as the Cornell potential. By choosing the generalized fractional derivative, the fractional Nikiforov–Uvarov method is applied as a good efficient tool. The energy eigenvalues and corresponding wave functions are obtained in the sense of fractional forms by solving DE analytically. The special case is obtained, which is compatible with the classical model. In addition, we applied the present results on the light mesons such as D , D s and B s. Solving the fractional DE will open a new path to solve and improve results in the classical relativistic quantum systems. [ABSTRACT FROM AUTHOR]

In this paper, we consider the soft-wall holographic model with the linear dilaton background. The model leads to a Hydrogen-like meson spectrum which can be interpreted as the static limit with very large quark masses when the Coulomb interaction dominates. The mass scale introduced by the linear dilaton is matched to the quark mass. The resulting model is analyzed for the scalar, vector and tensor cases. The electromagnetic coupling constants predicted by the model are decreasing with the radial number in contrast to the soft-wall model with quadratic dilaton where these couplings represent a universal constant. The given prediction is qualitatively consistent with the corresponding experimental data in vector quarkonia. The proposed model can thus be used as a constituent part of more elaborated holographic models for heavy quarkonia. A particular example of such a model is put forward. [ABSTRACT FROM AUTHOR]

We investigate the weak leptonic and semileptonic decay widths of pseudoscalar light and heavy mesons in a Dirac formalism. We take relativistic-independent quark model of the form V q (r) = 1 2 (1 + γ 0) (a 2 r + V 0) , where a > 0. This is computed using the binding quark eigenfunction and taking the assumptions of a significant relationship between the quark and antiquark momenta inside the decaying meson in the rest frame. To calculate the decay constant (f M) , decay width and branching fractions of pseudoscalar mesons, we employ the model parameters that we used earlier. The experimental findings and various similar models are in good agreement with our predictions such as " f B C > f B S > f B , f D S > f D , f D > f B and f B > f π ". Finally, we calculate the form factors and branching fractions for the semileptonic D (D 0) decays " D + → K S 0 e + ν e ,  D + → K L 0 e + ν e ,  D + → π 0 e + ν e ,  D 0 → K − e + ν e and D 0 → π − e + ν e " and find reasonable agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Recently, the BESIII Collaboration reported that there exist two explicit enhancement structures near 2.25 GeV, one has the mass of M = 2 2 3 2 ± 1 9 ± 2 7 MeV and the width of Γ = 9 3 ± 5 3 ± 2 0 MeV and another structure has the mass of M = 2 2 0 0 ± 1 1 ± 1 7 MeV and the width of Γ = 7 4 ± 2 0 ± 2 4 MeV when analyzing the cross section of subprocesses. Earlier, the BESIII Collaboration reported the existence of the X (2 2 2 0) , with a mass of 2 2 2 2 ± 7 ± 2 MeV and width of 5 9 ± 3 0 ± 6 MeV. Based on these experimental results, we carried out a study. We present the comparison of the mass spectrum between theoretical and experimental masses and examine the two-body strong decays of these states within two different approaches to the 3 P 0 model. We find that the newly discovered states are most likely to be an ω (3 D) state. This discovery could be useful in establishing entire ω mesons. [ABSTRACT FROM AUTHOR]

The branching fractions of τ → π + π − π − ν τ and τ → π − 2 π 0 ν τ are calculated within the chiral NJL model. Features of the axial-vector a 1 meson which play an important role in describing the τ decays are discussed. Permissible values for the mass and width of the a 1 meson are considered in accordance with the latest experiments. [ABSTRACT FROM AUTHOR]

In this work, the mass spectrum of the first radial excitation axial vector meson nonet is considered in the framework of the nonrelativistic constituent quark model and Regge phenomenology. After that, we investigate the strong decay characteristics of these states within the 3 P 0 model. The results are compared to values from other phenomenological models, and they may be beneficial in the prospective search for 2 3 P 1 meson nonets. [ABSTRACT FROM AUTHOR]

We propose methods to produce gamma light source, muon and energetic meson beams such as charged and neutral Kaons, which are boosted to be collimated and with relatively long lifetime. The first type of method is based on asymmetric electron positron collisions with a center-of-mass energy of, e.g. 1020 MeV, and Kaons can be produced at a rate of 1 0 4 − 5 ∕ s. The electron and positron beams are either asymmetric in energy, e.g. 10 GeV electron beam with 26 MeV positron beam, or asymmetric in space, e.g. 10 GeV electron and positron beams collisions with an angle around 0.05 radius. Such proposals should be able to be achieved with a reasonable budget. The other type of method relies on TeV positron on target experiment, where Kaon beams can be achieved at around 1 0 7 per bunch crossing. Such Kaon beams are clean with small contamination, and can have great physics potential on, e.g. hyperon searches through Kaon nuclei collision, Kaon rare decay measurement, and Kaon proton or Kaon lepton collisions. The same technique can also be extended to other final states such as pions and tau leptons. [ABSTRACT FROM AUTHOR]

In this work, we tried to predict the parameters of B c ∗ meson. Simple assumptions gave us the following parameters m B c ∗ = 6 3 2 9 ± 1 0 MeV and f B c ∗ = 5 3 5. 5 ± 5 7. 8 MeV (for Λ B c ∗ = 2. 2 6 ± 0. 1 4 GeV in covariant confined quark model). We calculated widths of radiative decays of B q ∗ mesons, where q = u ∕ d , s , c and compared them with other theoretical works. It was shown that the width of the B c ∗ meson is very sensitive to the mass m B c ∗ as expected and less to the size parameter Λ B c ∗ . [ABSTRACT FROM AUTHOR]

Nonleptonic B c decays to P -wave charmonia and light π + , K + , and ρ + , K ∗ + mesons are analyzed using factorization. The hadronic form factors parametrizing the B c → χ c J (h c) matrix elements are expressed in terms of universal functions at the leading order of an expansion in the relative velocity of the heavy quarks in the B c rest-frame and in 1 / m Q . Several ratios of branching fractions are evaluated, and when experimental information can be used, single branching fractions are presented. Both the 1 P and 2 P charmonia are considered. If the exotic candidate state χ c 1 (3 8 7 2) corresponds to χ c 1 (2 P) , it should be produced in nonleptonic B c decays with predicted abundances with respect to the other states in the charmonium 2 P spin four-plet. [ABSTRACT FROM AUTHOR]

We present a systematic study of the transverse mass ( m T − m) spectra of π 0 and η mesons in C u + A u collisions at s N N = 2 0 0 GeV, U + U collisions at s N N = 1 9 2 GeV, P b + P b collisions at s N N = 2. 7 6 TeV and p + P b collisions at s N N = 5. 0 2 TeV. The published data of invariant yields of π 0 and η mesons as a function of p T are taken from PHENIX and from ALICE collaborations in the mid-rapidity region for different centrality cases. The primary object is to check the similar suppression patterns and identical spectral shapes of π 0 and η mesons at different center-of-mass energies in different collision systems. We employ m T scaling approach to study the spectral shapes of η meson from the given pion ( π 0 ) spectra. For this purpose, we use the modified Hagedorn function as a fit function. We obtain m T scaled η π 0 ratio to study the spectral shape and suppression pattern of π 0 and η mesons. This ratio is useful to obtain the decay contribution of π 0 and η mesons in photonic and leptonic channels but also points to the quantitative changes in the dynamics of the heavy ion collisions. [ABSTRACT FROM AUTHOR]

The axion or axion-like particle (ALP) is one of the best motivated particle candidates beyond the Standard Model (SM). Its rich phenomenology has been extensively studied in various low- and high-energy experiments. However, there are relatively few studies about the couplings of ALP with neutrinos at collider experiments. In the context of the simple ℓ ALP scenario, we consider the contributions of ℓ ALP via the couplings a ν ν ̄ to the decays Z → ν ν ̄ , H → ν ν ̄ , W → ℓ ν and P ± → ℓ ± ν with P being charged pseudoscalar meson. Comparing our numerical results with the corresponding experimental measured values, we derive constraints on the coupling parameter g ν and the ℓ ALP mass m a . The constraints on g ν from the decay P ± → ℓ ± ν are generally stricter than those from other decays, the strictest constraint comes from the decay K ± → ℓ ± ν , which is g ν ≲ 6. 4 × 1 0 − 4 (2. 4 × 1 0 − 2) for m a = 1  MeV (400 MeV). [ABSTRACT FROM AUTHOR]

We present a calculation of the masses of the isovector mesons (vector, scalar and pseudoscalar including the established recurrences) using a new method of finite energy QCD sum rules. The method is based on the idea of choosing a suitable integration kernel which minimizes the occurring integral over the cut in the complex energy (squared) plane. We obtain remarkably stable results in a wide range R , where R is the radius of the integration contour. The sum rule predictions agree with the experimental values within the expected accuracy showing that QCD describes single resonances. [ABSTRACT FROM AUTHOR]

In this paper, we incorporate three-loop contributions in the strong coupling constant and study their effects in the wave functions, masses and decay constants of heavy–light pseudo-scalar mesons (PSM) D , D s , B and B s in V-scheme. In this work, we use the standard linear plus inverse distance QCD potential in association with Dalgarno's method of perturbation theory for linear parent option. Detailed comparison is done with the results from Lattice QCD, QCD sum rules, light-front quark model (LFQM), relativistic harmonic confinement model (RHCM) and recent PDG data. [ABSTRACT FROM AUTHOR]

We present results on Spin Density Matrix Elements (SDMEs) measured in hard exclusive muoproduction of ρ 0 and ω mesons on the proton at COMPASS using 160 GeV/ c polarized μ + and μ − beams scattering off a liquid hydrogen target. The measurements cover the range 5 GeV/ c 2 < W < 17 GeV/ c 2 , 1.0 (GeV/ c)2 < Q 2 < 10.0 (GeV/ c)2 and 0.01 (GeV/ c)2 < p T 2 < 0.5 (GeV/ c)2. Here, Q 2 denotes the virtuality of the exchanged photon, W the mass of the final hadronic system and p T the transverse momentum of the vector meson with respect to the virtual-photon direction. The measured non-zero SDMEs for transitions of transversely polarized virtual photons to longitudinally polarized vector mesons ( γ T → V L ) indicate a violation of s -channel helicity conservation. Additionally, for ρ 0 production we observe a dominant contribution of natural-parity-exchange transitions and a small contribution of unnatural-parity-exchange transitions. On the contrary, the contribution of unnatural-parity-exchange for ω production is significant and it decreases with increasing W , being still non-negligible at the largest W values accessible at COMPASS. The results provide an important input for modeling Generalized Parton Distribution (GPDs). [ABSTRACT FROM AUTHOR]

In this paper, we use the concept of conformable fractional derivative to study the nonrelativistic radial Schrödinger equation. We suggest an extended version of the Cornell potential as the quark–antiquark interaction of light and heavy mesons. We generalize the asymptotic iteration method to the fractional domain. The latter is used to calculate the energy eigenvalues, as well as the effect of the fractional order ν on energy spectra. To test the applicability of our model, we use the obtained results to reproduce the mass spectra of some light and heavy mesons such as b b ̄ , c c ̄ , c s ̄ , b ̄ c , b q ̄ and b s ̄ quarks. The mass spectra are obtained at different values of the fractional order parameter ν and were compared with experimental results and other relevant theoretical works. Using the wave function, we calculated the decay constants for heavy-light D 0 , D + , D s + , B − , B ̄ 0 and B ̄ s 0 mesons. Our results are found to be in good agreement with the experimental data, and improved in comparison with other theoretical previsions. [ABSTRACT FROM AUTHOR]

In-medium masses of the pseudoscalar and vector open bottom mesons (B , B ̄ , B s and B ∗ , B ̄ ∗ , B s ∗ ) are studied in the magnetized nuclear matter by considering the effects of Dirac sea, within the chiral effective model. The mass modifications arise due to the interactions of the open bottom mesons with the nucleons and the scalar mesons, calculated in terms of the scalar and number densities of the nucleons and the scalar fields fluctuations, within the chiral model. The effects of the magnetized Dirac sea lead to the considerable changes in the scalar fields with increasing magnetic field, which are related to the condensates of light quark–antiquark pairs. There is observed to be a (reduction) enhancement in the QCD light quark condensates with rising magnetic field, a phenomenon called (inverse) magnetic catalysis. The contribution of the magnetic field on the Fermi sea of nucleons is also taken into account through protons Landau energy levels and anomalous magnetic moments (AMMs) of the nucleons. The additional contribution of the lowest Landau level for the charged mesons is taken into account. In the presence of an external magnetic field, the spin–magnetic field interaction between the longitudinal component of the vector mesons and the pseudoscalar mesons (B − B ∗ ∥ , B ̄ − B ̄ ∗ ∥ and B s − B s ∗ ∥ ) are studied, which lead to level repulsion between their masses with increasing magnetic field. The magnetic fields are observed to have significant contribution on the masses of the open bottom mesons through the Dirac sea effects taking into account the AMMs of nucleons. In vacuum, appreciable medium modifications are obtained due to the magnetized Dirac sea contribution with nonzero nucleonic AMMs. [ABSTRACT FROM AUTHOR]

In this paper, we apply the method of QCD sum rules to study the doubly heavy tetraquark states Q Q q ̄ n ̄ with spin-parity J P = 1 + and strangeness S = 0 , − 1 using careful estimates of the Borel and threshold parameters involved. Masses of the doubly bottom and charmed tetraquarks with isospin I = 0 , 1 / 2 , 1 are computed precisely via taking into account multifarious condensates up to dimension 10. Compared with the two-heavy meson thresholds, we find that all nonstrange doubly-bottom tetraquarks and a doubly-charmed tetraquarks associated with J 3 with J P = 1 + are stable against strong decay into two bottom mesons while a doubly-charmed tetraquark associated with current J 2 is unstable against strong decay. By the way, weak decay widths of the doubly bottom tetraquarks are also given. [ABSTRACT FROM AUTHOR]

During the past 40 years, the production of pairs of J ∕ ψ mesons in high-energy hadron collisions has been studied by several experiments. Despite the experimental and theoretical efforts, the origin of the process and the relative weight of different production mechanisms remain unknown. Depending on the energy scale, the double J ∕ ψ production can be described by single- and/or double-parton scattering sub-processes and gluon–gluon fusion or quark–antiquark annihilation mechanisms. The process can also be related to the hypothesis of the intrinsic charm of hadrons and the existence of exotic tetraquark states which were predicted by various theoretical models and have recently been observed by the LHCb experiment. To study dimuon pair production, the COMPASS experiment at CERN uses a 190 GeV/ c negative pion beam impinging on different nuclear targets. First preliminary COMPASS results on J ∕ ψ pair production will be presented. The search for possible signals from exotic resonances and the study of double J ∕ ψ production mechanisms will be discussed. [ABSTRACT FROM AUTHOR]

In the paper, we construct eight color singlet–singlet-type five-quark currents with distinguished isospins to study the D ̄ Ξ ′ , D ̄ Ξ c ∗ , D ̄ ∗ Ξ c ′ and D ̄ ∗ Ξ c ∗ molecular states with strangeness via the QCD sum rules. Numerical results show that the central values of the pentaquark masses with higher (lower) isospin are slightly above (below) the thresholds of the corresponding meson–baryon pairs, and support assigning the P c s (4 4 5 9) as the D ̄ Ξ c ∗ molecular state with the quantum numbers I J P = 0 3 2 − . The other predictions can be confronted to the experimental data in the future. [ABSTRACT FROM AUTHOR]

The prediction of properties of the low-energy portion of the hadronic spectrum is a challenging task which, up to day, is still tentatively given due to the nonperturbative nature of quantum chromodynamics (QCD) at low energies. In this paper, we are exploring the validity of the SO(4) scheme, as a representative of the fundamental QCD structure of meson-like states in the region below 2.5 GeV. We have focused our attention on the calculation of the energy and width of meson states of various spin, isospin and parities. [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]

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]

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]

The mass spectra and decay properties of B and B s mesons are obtained using the nonrelativistic potential model by applying the variational approach. The quark–anti-quark potential used in our model consists of a Hulthen potential and a confining linear potential. The hyper-fine interaction is introduced to obtain the splittings of the spin-singlet and triplet states, while the spin–orbit and tensor interactions provide the fine structure splittings. The model parameters and the wave functions that reproduce the mass spectra are used to investigate the decay properties of B and B s mesons. The mass spectra of B and B s mesons have been enhanced using coupled channel effects. [ABSTRACT FROM AUTHOR]

In this work, we calculate the mass spectrum of the bottom mesons with a modified nonrelativistic quark model by involving the screening effect, and explore their strong decay properties within the 3P0 model. Our results suggest that the B 1 (5 7 2 1) , B 2 ∗ (5 7 4 7) , B J (5 8 4 0) and B J (5 9 7 0) could be reasonably assigned as the B 1 ′ (1 P) , B (1 3 P 2) , B (2 1 S 0) and B (1 3 D 3) , respectively. The more precise measurements of the excited bottom mesons are crucial to confirm these assignments. [ABSTRACT FROM AUTHOR]

The in-medium partial decay widths of Υ (4 S) → B B ̄ in magnetized asymmetric nuclear matter are studied using a field theoretic model for composite hadrons with quark (and antiquark) constituents. Υ (4 S) is the lowest bottomonium state which can decay to B B ̄ in vacuum. The medium modifications of the decay widths of Υ (4 S) to B B ̄ pair in magnetized matter arise due to the mass modifications of the decaying Υ (4 S) as well as of the produced B and B ̄ mesons. The in-medium masses of the open bottom meson in magnetized nuclear matter are computed from their interactions with the nucleons and the scalar mesons within a chiral effective model. The mass modification of the Υ (4 S) arises due to the medium modification of a scalar dilaton field, which is introduced in the model to simulate the gluon condensates of QCD. The effects of the anomalous magnetic moments for the proton and neutron are taken into consideration in the present investigation. The presence of the external magnetic field is observed to lead to different mass modifications within the B (B + , B 0) as well as the B ̄ (B − , B 0 ̄) doublets, even in isospin symmetric nuclear matter. This is due to the difference in the interactions of the proton and the neutron to the electromagnetic field. The charged B ± mesons have additional contributions from the Landau energy levels, leading to positive shifts in their masses in the presence of a magnetic field. In the presence of an external magnetic field, there are contributions to the masses of the B, B ̄ mesons and Υ (4 S) state (longitudinal component) due to the pseudoscalar meson–vector meson (PV) mixing (B − B ∗ , B ̄ − B ∗ ̄ and Υ (4 S) − η b (4 S) mixings), which are also considered in this study. The PV mixing effects are observed to be the dominant contributions to the mass shifts of these mesons, which lead to appreciable modifications in the decay widths of Υ (4 S) to the neutral ( B 0 B 0 ̄) and the charged ( B + B − ) pairs in the presence of a magnetic field. These should have observable consequence in the production of open bottom mesons and bottomonium states at LHC and RHIC, where huge magnetic fields are produced in ultra-relativistic peripheral heavy-ion collisions. [ABSTRACT FROM AUTHOR]

The most precise measurement of decay-time-dependent CP violation in the decays of B 0 → J / ψ K S 0 and B 0 → ψ (2 S) K S 0 was reported by LHCb collaboration with the values of S J / ψ K S 0 = 0. 8 3 ± 0. 0 8 ± 0. 0 1 , C J / ψ K S 0 = 0. 1 2 ± 0. 0 7 ± 0. 0 2 and S ψ (2 S) K S 0 = 0. 8 4 ± 0. 1 0 ± 0. 0 1 , C ψ (2 S) K S 0 = − 0. 0 5 ± 0. 1 0 ± 0. 0 1. In this study, the parameters of CP violation in these decay modes have been calculated under the factorization approach. In these decays, CP violation in the interference of mixing and decay has has arisen from decay-time-dependent asymmetry. This type of CP violation has been characterized by Im λ f ≠ 0. We have estimated the parameters of S J / ψ K S 0 = 0. 8 8 ± 0. 0 0 and C J / ψ K S 0 = 0. 1 1 ± 0. 0 1 for the B 0 → J / ψ K S 0 decay and S ψ (2 S) K S 0 = 0. 8 9 ± 0. 0 1 and C ψ (2 S) K S 0 = − 0. 0 4 ± 0. 0 2 correspond to the B 0 → ψ (2 S) K S 0 decay which are compatible with the experimental values approved by the LHCb collaboration. In the following, we have obtained the value of sin 2 β. Finally, we have calculated the total amplitude and obtained comparable results with the experimental values for the branching ratios of both decays. [ABSTRACT FROM AUTHOR]

In this paper, the form factors of D(s) to light tensor mesons a2(1320), K 2 ∗ (1 4 3 0) , f 2 (1 2 7 0) , f 2 ′ (1 5 2 5) and corresponding semileptonic decays are investigated through the method of light cone sum rules (LCSR) in the framework of heavy quark effective field theory (HQEFT). Considering the light cone distribution amplitudes (DAs) of tensor mesons to twist-3, we give numerical results of form factors systematically, which are necessary inputs for the analysis of relevant D(s) decays. Based on the form factor results, the relevant semileptonic decays induced by charged current (CC) as well as flavor changing neutral current (FCNC) are studied. Our predictions for the branching ratios, longitudinal polarization fractions and forward–backward asymmetries can be tested by more precise experiments such as LHCb, BESIII and BelleII in the future. [ABSTRACT FROM AUTHOR]