Non-strange Mesons Research Articles

Measurement of beauty-quark production in pp collisions at s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document} = 13 TeV via non-prompt D mesons

The pT-differential production cross sections of non-prompt D0, D+, and Ds+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\ extrm{D}}_{\ extrm{s}}^{+} $$\\end{document} mesons originating from beauty-hadron decays are measured in proton–proton collisions at a centre-of-mass energy s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document} = 13 TeV. The measurements are performed at midrapidity, |y| < 0.5, with the data sample collected by ALICE from 2016 to 2018. The results are in agreement with predictions from several perturbative QCD calculations. The fragmentation fraction of beauty quarks to strange mesons divided by the one to non-strange mesons, fs/(fu + fd), is found to be 0.114 ± 0.016 (stat.) ± 0.006 (syst.) ± 0.003 (BR) ± 0.003 (extrap.). This value is compatible with previous measurements at lower centre-of-mass energies and in different collision systems in agreement with the assumption of universality of fragmentation functions. In addition, the dependence of the non-prompt D meson production on the centre-of-mass energy is investigated by comparing the results obtained at s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document} = 5.02 and 13 TeV, showing a hardening of the non-prompt D-meson pT-differential production cross section at higher s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document}. Finally, the bb¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \ extrm{b}\\overline{\ extrm{b}} $$\\end{document} production cross section per unit of rapidity at midrapidity is calculated from the non-prompt D0, D+, Ds+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\ extrm{D}}_{\ extrm{s}}^{+} $$\\end{document}, and Λc+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\Lambda}_{\ extrm{c}}^{+} $$\\end{document} hadron measurements, obtaining dσ/dy=75.2±3.2stat.±5.2syst.−3.2+12.3extrap.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \ extrm{d}\\sigma /\ extrm{d}y=75.2\\pm 3.2\\left(\ extrm{stat}.\\right)\\pm 5.2{\\left(\ extrm{syst}.\\right)}_{-3.2}^{+12.3}\\left(\ extrm{extrap}.\\right) $$\\end{document} μb.

Revisiting the pion Regge trajectories

We propose a model-independent ansatz M=βx(x+c0)ν+c1 (x=l,nr) and then use it to fit the orbital and radial pion Regge trajectories without the preset values. It is shown that nonzero c1 is reasonable and acceptable. Nonzero c1 gives an explanation for the nonlinearity of the pion Regge trajectories in the usually employed (M2,x) plane. As mR or c1 is chosen appropriately, both the orbital and radial pion Regge trajectories are linear in the ((M−mR)2,x) plane whether the π0 is included or not on the Regge trajectories. The fitted pion Regge trajectories suggest 0.45≤ν≤0.5, which indicates the confining potential ra with 9/11≤a≤1. Moreover, it is illustrated in the appendix B that mR can be nonzero for the light nonstrange mesons. We present discussions in the appendix A on the structure of the Regge trajectories plotted in the (M,x) plane and on the structure of the Regge trajectories in the ((M−mR)2,x) plane based on the potential models and the string models.

On Asymptotic Regge Trajectories of Heavy Meson Resonances

We performed the analysis of the asymptotic behavior of Regge trajectories of nonstrange and strange mesons and found that thewidth of heavy hadrons for these trajectories cannot linearly depend on their mass. Such a finding clearly demonstrates that a widely spread belief on the linear mass dependence of the resonance width contradicts the linearity of Regge trajectories on theMandelstam variable s. Using the data on masses and widths for ρJ––, ωJ––, aJ++,, and fJ++ mesons with the spin values J ≤ 6 and for K*J mesons with J ≤ 5, we extracted the parameters of the asymptotically linear Regge trajectories predicted by the finite-width model of quark gluon bags. It is shown that the parameters obtained for the data sets B and D are consistent with the cross-over temperaturedetermined by the lattice QCD simulations at the vanishing baryonic density and with the kinetic freeze-out temperature of early hadronizing particles found in relativistic heavy ion collisions at and above the highest SPS energy. Comparing the resonance width of sets B and D evaluated at the masses of Z and W bosons, respectively, we discovered that the calculated width values match that of the gauge bosons. We argue that such matches provide us with indirect, but the first experimental evidence for the compositeness of Z and W bosons. Based on these findings, we assume that Z, W, and Higgs bosons have the Regge trajectories which are similar to the asymptotic trajectories of the studied mesons. The predictions for the masses and widths of the Regge partners of Z and W bosons and for the mass dependence of the widths of Higgs boson Regge partners along with the values for the mass and width of the scalar Higgs mesons are made as well.

Observation of Ds±/D0 Enhancement in Au+Au Collisions at sNN=200 GeV

We report on the first measurement of charm-strange meson D_{s}^{±} production at midrapidity in Au+Au collisions at sqrt[s_{NN}]=200 GeV from the STAR experiment. The yield ratio between strange (D_{s}^{±}) and nonstrange (D^{0}) open-charm mesons is presented and compared to model calculations. A significant enhancement, relative to a pythia simulation of p+p collisions, is observed in the D_{s}^{±}/D^{0} yield ratio in Au+Au collisions over a large range of collision centralities. Model calculations incorporating abundant strange-quark production in the quark-gluon plasma and coalescence hadronization qualitatively reproduce the data. The transverse-momentum integrated yield ratio of D_{s}^{±}/D^{0} at midrapidity is consistent with a prediction from a statistical hadronization model with the parameters constrained by the yields of light and strange hadrons measured at the same collision energy. These results suggest that the coalescence of charm quarks with strange quarks in the quark-gluon plasma plays an important role in D_{s}^{±}-meson production in heavy-ion collisions.

Repulsive properties of hadrons in lattice QCD data and neutron stars

Second-order susceptibilities $\chi^{11}_{ij}$ of baryon, electric, and strangeness, $B$, $Q$, and $S$, charges, are calculated in the Chiral Mean Field (CMF) model and compared to available lattice QCD data. The susceptibilities are sensitive to the short range repulsive interactions between different hadron species, especially to the hardcore repulsion of hyperons. Decreasing the hyperons size, as compared to the size of the non-strange baryons, does improve significantly the agreement of the CMF model results with the Lattice QCD data. The electric charge-dependent susceptibilities are sensitive to the short range repulsive volume of mesons. The comparison with lattice QCD data suggests that strange baryons, non-strange mesons and strange mesons have significantly smaller excluded volumes than non-strange baryons. The CMF model with these modified hadron volumes allows for a mainly hadronic description of the QCD susceptibilities significantly above the chiral pseudo-critical temperature. This improved CMF model which is based on the lattice QCD data, has been used to study the properties of both cold QCD matter and neutron star matter. The phase structure in both cases is essentially unchanged, i.e. a chiral first-order phase transition occurs at low temperatures ($T_{\rm CP}\approx 17$ MeV), and hyperons survive deconfinement to higher densities than non-strange hadrons. The neutron star maximal mass remains close to 2.1$M_\odot$ and the mass-radius diagram is only modified slightly due to the appearance of hyperons and is in agreement with astrophysical observations.

Measurement of beauty and charm production in pp collisions at sqrt{s} = 5.02 TeV via non-prompt and prompt D mesons

The pT-differential production cross sections of prompt and non-prompt (produced in beauty-hadron decays) D mesons were measured by the ALICE experiment at midrapidity (|y|< 0.5) in proton-proton collisions at sqrt{s} = 5.02 TeV. The data sample used in the analysis corresponds to an integrated luminosity of (19.3 ± 0.4) nb−1. D mesons were reconstructed from their decays D0→ K−π+, D+→ K−π+π+, and {mathrm{D}}_{mathrm{s}}^{+}to upphi {uppi}^{+}to {mathrm{K}}^{-}{mathrm{K}}^{+}{uppi}^{+} and their charge conjugates. Compared to previous measurements in the same rapidity region, the cross sections of prompt D+ and {mathrm{D}}_{mathrm{s}}^{+} mesons have an extended pT coverage and total uncertainties reduced by a factor ranging from 1.05 to 1.6, depending on pT, allowing for a more precise determination of their pT-integrated cross sections. The results are well described by perturbative QCD calculations. The fragmentation fraction of heavy quarks to strange mesons divided by the one to non-strange mesons, fs/(fu + fd), is compatible for charm and beauty quarks and with previous measurements at different centre-of-mass energies and collision systems. The mathrm{b}overline{mathrm{b}} production cross section per rapidity unit at midrapidity, estimated from non-prompt D-meson measurements, is mathrm{d}{sigma}_{mathrm{b}overline{mathrm{b}}}/mathrm{d}yleft|{}_{left|mathrm{y}right|<0.5}=34.5pm 2.4{left(mathrm{stat}right)}_{-2.9}^{+4.7}left(mathrm{tot}.mathrm{syst}right)right. μb. It is compatible with previous measurements at the same centre-of-mass energy and with the cross section pre- dicted by perturbative QCD calculations.

Production of K*(892)° mesons in Cu+Au collisions at = 200 GeV and U+U collisions at = 192 GeV

Studying the properties and evolution of the QGP is one of the main goals in modern heavy ion physics. Due to strange quark content K*0 meson is a good probe for the study of QGP formed in heavy-ion collisions. K *0-meson production was previously measured by PHENIX in symmetric Cu+Cu collisions at = 200 GeV and U+U collisions at = 200 GeV. K *0-meson production in asymmetric Cu+Au collisions at = 200 GeV and U+U collisions at = 200 GeV and spherically asymmetric uranium nuclei at = 200 GeV and U+U collisions at = 192 GeV was performed for continuation the study of the QGP properties. This report presents invariant transverse momentum spectra and nuclear modification factors of K *0-mesons which were measured in Cu+Au collisions at the energy of = 200 GeV and U+U collisions at = 200 GeV and U+U collisions at the energy of = 200 GeV and U+U collisions at = 192 GeV. In results, K *0-mesons yields are less suppressed than the yields of non-strange mesons, which might indicate that additional particle production mechanisms are involved in the K *0-meson production. The production of the K *0-mesons in Cu+Cu, Cu+Au, and U+U collisions scales with Npart and seems to depend on nuclear overlap size, but not on its geometry.

The BGOOD experimental setup at ELSA

The BGOOD experiment at the ELSA facility in Bonn has been commissioned within the framework of an international collaboration. The experiment pursues a systematic investigation of non-strange and strange meson photoproduction, in particular t-channel processes at low momentum transfer. The setup uniquely combines a central almost 4pi acceptance BGO crystal calorimeter with a large aperture forward magnetic spectrometer providing excellent detection of both neutral and charged particles, complementary to other setups such as Crystal Barrel, Crystal Ball, LEPS and CLAS.

Strange matter and kaon to pion ratio in the SU(3) Polyakov–Nambu–Jona-Lasinio model

The behavior of strange matter in the frame of the SU(3) Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model including the ${U}_{A}(1)$ anomaly is considered. We discuss the appearance of a peak in the ratio of the number of strange mesons to nonstrange mesons known as the ``horn.'' The PNJL model gives a schematic description of the chiral phase transition and meson properties at finite temperature and density. By using the model, we can show that the splitting of kaon and antikaon masses appears as a result of the introduction of density. This may explain the difference in the ${K}^{+}/{\ensuremath{\pi}}^{+}$ ratio and the ${K}^{\ensuremath{-}}/{\ensuremath{\pi}}^{\ensuremath{-}}$ ratio at low $\sqrt{{s}_{NN}}$ and their tendency to the same value at high $\sqrt{{s}_{NN}}$. We also show that the rise in the ratio ${K}^{+}/{\ensuremath{\pi}}^{+}$ appears near the critical endpoint when we build the ${K}^{+}/{\ensuremath{\pi}}^{+}$ ratio along the phase-transition diagram and it can be considered as a critical region signal.

A Multiquark Approach to Excited Hadrons and Regge Trajectories

We propose a novel approach to construction of hadron spectroscopy. The case of light nonstrange mesons is considered. By assumption, all such mesons above 1 GeV appear due to creation of constituent quark-antiquark pairs inside π or ρ(ω) mesons. These spin-singlet or triplet pairs dictate the quantum numbers of formed resonance. The resulting classification of light mesons turns out to be in a better agreement with the experimental observations than the standard quark model classification. It is argued that the total energy of quark components should be proportional to the hadron mass squared rather than the linear mass. As a byproduct a certain relation expressing the constituent quark mass via the gluon and quark condensate is put forward. We show that our approach leads to an effective mass counting scheme for meson spectrum and results in the linear Regge and radial Regge trajectories by construction. An experimental observation of these trajectories might thus serve as evidence not for string but for multiquark structure of highly excited hadrons.

Glueballs and deconfinement temperature in AdS/QCD

We put forward an alternative way to estimate the deconfinement temperature in bottom-up holographic models. The deconfinement in AdS/QCD is related to the Hawking-Page phase transition, in which the critical Hawking temperature is identified with the deconfinement one in the gauge theory. The numeric estimation of the latter is only possible when the parameters of a $5D$ dual model are previously determined from consistency with other physical aspects, standardly, providing a description of the QCD resonances. The traditional way to fix parameters in the simplest AdS/QCD models is to reproduce the mass of the $\rho$ meson or the slope of the approximate radial Regge trajectory of the $\rho$ excitations. Motivated by a general idea that the slope value originates in gluodynamics, we propose calculating the deconfinement temperature using the trajectory of scalar glueballs. We consider several holographic models and use the recent idea of isospectral potentials to make an additional check of the relevance of our approach. It is demonstrated that different models from an isospectral family (i.e. the models leading to identical predictions for spectrum of hadrons with fixed quantum numbers) result in different predictions for the deconfinement temperature. This difference is found to be quite small in the scalar glueball channel but very large in the vector meson channel. The observed stability in the former case clearly favours the choice of the glueball channel for thermodynamic predictions in AdS/QCD models. For a balanced approach, we argue that either assuming $f_0(1500)$ to have a dominating component of $0^{++}$ glueball or accepting the idea of the universality in the radial Regge trajectories of light non-strange vector mesons one can reproduce the results for the deconfinement temperature obtained before in the lattice simulations in the background of non-dynamical quarks.

Measurement of the Absolute Branching Fraction of the Inclusive Semileptonic Λ_{c}^{+} Decay.

Using a data sample of e^{+}e^{-} collisions corresponding to an integrated luminosity of 567 pb^{-1} collected at a center-of-mass energy of sqrt[s]=4.6 GeV with the BESIII detector, we measure the absolute branching fraction of the inclusive semileptonic Λ_{c}^{+} decay with a double-tag method. We obtain B(Λ_{c}^{+}→Xe^{+}ν_{e})=(3.95±0.34±0.09)%, where the first uncertainty is statistical and the second systematic. Using the known Λ_{c}^{+} lifetime and the charge-averaged semileptonic decay width of nonstrange charmed mesons (D^{0} and D^{+}), we obtain the ratio of the inclusive semileptonic decay widths Γ(Λ_{c}^{+}→Xe^{+}ν_{e})/Γ[over ¯](D→Xe^{+}ν_{e})=1.26±0.12.

Two-pole structure of the [formula omitted

The so far only known charmed non-strange scalar meson is dubbed as D0⁎(2400) in the Review of Particle Physics. We show, within the framework of unitarized chiral perturbation theory, that there are in fact two (I=1/2,JP=0+) poles in the region of the D0⁎(2400) in the coupled-channel Dπ, Dη and DsK¯ scattering amplitudes. With all the parameters previously fixed, we predict the energy levels for the coupled-channel system in a finite volume, and find that they agree remarkably well with recent lattice QCD calculations. This successful description of the lattice data is regarded as a strong evidence for the two-pole structure of the D0⁎(2400). With the physical quark masses, the poles are located at (2105−8+6−i102−12+10) MeV and (2451−26+36−i134−8+7) MeV, with the largest couplings to the Dπ and DsK¯ channels, respectively. Since the higher pole is close to the DsK¯ threshold, we expect it to show up as a threshold enhancement in the DsK¯ invariant mass distribution. This could be checked by high-statistic data in future experiments. We also show that the lower pole belongs to the same SU(3) multiplet as the Ds0⁎(2317) state. Predictions for partners in the bottom sector are also given.

Recoil polarization measurements

Polarization observables in photon-induced meson production off nucleons have long been recognized to hold the promise of a detailed understanding of the excited states in the excitation spectrum of the nucleon. Photon beam and proton target polarization are routinely used at the ELSA facility in the Crystal Barrel/TAPS experiment and have yielded a wealth of data on contributing partial waves and nucleon resonances. A detector study on how to complement these ongoing studies by recoil polarization measurements that offer an orthogonal approach with otherwise unmeasurable observables in the field of non-strange meson photoproduction has been performed.Building on experience with silicon detectors operated in the photon beamline environment, first possible layouts of Si detector telescopes for recoil protons were developed. Various geometries, e.g. Archimedean spiral design of annular sensors, sector shapes and rectangular sensors were studied and have been used during test measurements. A prototype for the recoil polarimeter was built and subjected to performance tests in protonproton scattering at the COSY-accelerator in Julich.

Mass spectra of heavy-light mesons in heavy hadron chiral perturbation theory

We study the masses of the low-lying charm and bottom mesons within the framework of heavy- hadron chiral perturbation theory (HHChPT). We work to third order in the chiral expansion, where meson loops contribute. In contrast to previous approaches, we use physical meson masses in evaluating these loops. This ensures that their imaginary parts are consistent with the observed widths of the D-mesons. The lowest odd- and even-parity, strange and nonstrange charm mesons provide enough constraints to determine only certain linear combinations of the low-energy constants (LECs) in the effective Lagrangian. We comment on how lattice QCD could provide further information to disentangle these constants. Then we use the results from the charm sector to predict the spectrum of odd- and even-parity of the bottom mesons. The predicted masses from our theory are in good agreement with experimentally measured masses for the case of the odd-parity sector. For the even-parity sector, the B-meson states have not yet been observed; thus, our results provide useful information for experimentalists investigating such states. The near degeneracy of nonstrange and strange scalar B mesons is confirmed in our predictions using HHChPT. We show why previous approaches of using HHChPT in studying the mass degeneracy in the scalar states of charm and bottom meson sectors gave unsatisfactory results.

Photoproduction ofa0(980)andf0(980)

There is no generally accepted view of the structure of the light-quark non-strange scalar mesons. A variety of models have been proposed that encompass $qq\bar{q}\bar{q}$, molecular, $q\bar{q}$ and glueball states in various combinations. Previously we considered scalar-meson photoproduction in a simple Regge-pole model and showed that it was experimentally viable. Recent data on the photoproduction of $a_0(980)$ and $f_0(980)$ confirm this. We extend our model to incorporate Regge cuts, based on our knowledge of $\pi^0$ photoproduction. The theoretical predictions are compared to the $a_0(980)$ and $f_0(980)$ photoproduction data.

EQUATION OF STATE FOR NEUTRON STARS WITH HYPERONS AND QUARKS IN THE RELATIVISTIC HARTREE–FOCK APPROXIMATION

We construct the equation of state (EoS) for neutron stars explicitly including hyperons and quarks. Using the quark-meson coupling model with relativistic Hartree-Fock approximation, the EoS for hadronic matter is derived by taking into account the strange ($\sigma^{\ast}$ and $\phi$) mesons as well as the light non-strange ($\sigma$, $\omega$, $\vec{\pi}$ and $\vec{\rho}$) mesons. Relevant coupling constants are determined to reproduce the experimental data of nuclear matter and hypernuclei in SU(3) flavor symmetry. For quark matter, we employ the MIT bag model with one-gluon-exchange interaction, and Gibbs criteria for chemical equilibrium in the phase transition from hadrons to quarks. We find that the strange vector ($\phi$) meson and the Fock contribution make the hadronic EoS stiff, and that the maximum mass of a neutron star can be consistent with the observed mass of heavy neutron stars even if the coexistence of hadrons and quarks takes place in the core. However, in the present calculation the transition to pure quark matter does not occur in stable neutron stars. Furthermore, the lower bound of the critical chemical potential of the quark-hadron transition at zero temperature turns out to be around 1.5 GeV in order to be consistent with the recent observed neutron star data.

Strong decay widths and coupling constants of recent charm meson states

Open charm hadrons with strange and non-strange mesons have been discovered in recent years. We study the spectra of several newly observed resonances by different collaborations like BaBar (del Amo Sanchez et al., Phys Rev D 82:111101, 2010) and LHCb (Aaij et al. [LHCb Collaboration], J High Energy Phys 1309:145, 2013) etc. Using an effective Lagrangian approach based on heavy quark symmetry and chiral dynamics, we explore the strong decay widths and branching ratios of various resonances and suggest their $$J^{p}$$ values. We try to fit the experimental data to find the coupling constants involved in the strong decays through pseudo-scalar mesons. The present work also discusses the possible spin–parity assignments of recently observed states by the LHCb Collaboration. The tentative assignment of the newly discovered state $$D_{J}^{*}(3000)$$ can be by natural parity states $$(0^{+},1^{-},2^{+},3^{-},\ldots )$$ , while $$D_{J}(3000)$$ can be identified with unnatural parity states like $$(0^{-},1^{+},2^{-},3^{+},\ldots )$$ . Therefore, the missing doublets 2S, 2D, 1F, 2P, and 3S can be thought of as filled up with these states. We study the two-body strong decay widths and branching ratios of missing doublets and plot the branching ratios vs. the mass of the decaying particle. These plots are used to thoroughly analyze all assignments to $$D_{J}(3000)$$ and various possibilities for the $$J^{P}$$ values.

Importance of Nonperturbative QCD Parameters for Bottom Mesons

The importance of nonperturbative quantum chromodynamics (QCD) parameters is discussed in context to the predicting power for bottom meson masses and isospin splitting. In the framework of heavy quark effective theory, the work presented here focuses on the different allowed values of the two nonperturbative QCD parameters used in heavy quark effective theory formula, and using the best fitted parameter, masses of the excited bottom meson states injp=1/2+doublet in strange and nonstrange sectors are calculated here. The calculated masses are found to be matching well with experiments and other phenomenological models. The mass splitting and hyperfine splitting have also been analyzed for both strange and nonstrange heavy mesons with respect to spin and flavor symmetries.

Meson Production in Proton--Proton Scattering Within an Extended Linear Sigma Model

We study the production of non-strange mesons in proton-proton scattering reactions within an effective model of mesons and baryons with global chiral symmetry. The model includes the nucleon ($N$) and its chiral partner ($N^{\ast}$) and their couplings to the $N_{f}=2$ multiplets of (pseudo-)scalar and (axial-)vector mesons. Results for the production of $\omega$ and $\eta$ mesons are presented.