Interaction Of Vector Mesons Research Articles

Impact of vector meson polarization on its interaction with matter

The production of unstable particles on different nuclei provides the possibility to determine the total cross section of the interaction of vector mesons V=rho ,omega ,varphi , K^{*0}(892),J/psi etc. with nucleons. This interaction is defined by a set of amplitudes that correspond to the transverse (helicity lambda =pm 1) or longitudinal (lambda =0) polarization of the vector meson. The total cross section for the interaction of transversely polarized vector mesons with nucleon sigma _T=sigma (V_T N) has been extracted from the coherent photoproduction of vector mesons off nuclei, while the vector meson production in charge exchange reactions as pi ^pm (K^pm )+Arightarrow V^0(K^{*0})+A' provides the unique opportunity to obtain the not yet measured total cross section for longitudinally polarized vector meson interacting with nucleon sigma _L=sigma (V_L N). We shortly discuss the importance of the knowledge of sigma _L and possibility to extract its value from experiments on nuclear target.

First characterization of the scattering length distribution of the vector meson interaction with the deuteron

First characterization of the scattering length distribution of the vector meson interaction with the deuteron

Vector meson-nucleon scattering length $$|\alpha _{VN}|$$ and trace anomalous energy contribution to the nucleon mass $$T_{A}$$

Low-energy scattering processes of vector meson and nucleon are an important window for studying non-perturbative QCD. The interaction of vector meson with nucleon, vector meson-nucleon scattering length $|\alpha_{VN}|$, is an important component of the study of hadronic interactions. Nowadays many scattering length values $|\alpha_{VN}|$ have been reported using the recent photoproduction experiment data or quasi data. In addition, the study of trace anomalous energy contribution to the proton mass is also a hot topic in non-perturbative QCD and hadron physics. However, it is difficult to measure proton trace anomalous energy experimentally, and the study of the trace anomaly of proton is still inconclusive. In this study, we established the relationship between the scattering length of the vector meson-proton $|\alpha_{Vp}|$ and the trace anomaly contribution of the proton mass $T_{A}$. With the scattering length values extracted by using the Vector Meson Dominance model, we obtained the trace anomaly contribution of the proton mass $T_{A}$ = (22.8$\%$ $\pm$ 1.2$\%$), which is of similar order of magnitude as the 23$\%$ given by Lattice QCD calculation. We conjecture that the trace anomaly contribution of nucleon is independent of the type of vector meson probe. We hope that high precision measurements of vector meson-nucleon scattering length could give us a better chance to explore the origin of the nucleon mass.

Nonperturbative quark matter equations of state with vector interactions

Nonperturbative equations of state (EoSs) for two and three quark flavors are constructed with the functional renormalization group (FRG) within a quark-meson model truncation augmented by vector mesons for low temperature and high density. Based on previous FRG studies without repulsive vector meson interactions the influence of isoscalar vector ω- and ϕ-mesons on the dynamical fluctuations of quarks and (pseudo)scalar mesons is investigated. The grand potential as well as vector meson condensates are evaluated as a function of quark chemical potential and the quark matter EoS in β-equilibrium is applied to neutron star (NS) physics. The tidal deformability and mass-radius relations for hybrid stars from combined hadronic and quark matter EoSs are compared for different vector couplings. We observe a significant impact of the vector mesons on the quark matter EoS such that the resulting EoS is sufficiently stiff to support two-solar-mass neutron stars.

Tau decay into nu _tau and a_1(1260), b_1(1235), and two K_1(1270)

We study the tau rightarrow nu _tau A decay, with A an axial-vector meson. We produce the a_1(1260) and b_1(1235) resonances in the Cabibbo favored mode and two K_1(1270) states in the Cabibbo suppressed mode. We take advantage of previous chiral unitary approach results where these resonances appear dynamically from the vector and pseudoscalar meson interaction in s-wave. Actually two different poles were obtained associated to the K_1(1270) quantum numbers. We find that the unmeasured rates for b_1(1235) production are similar to those of the a_1(1260) and for the two K_1 states we suggest to separate the present information on the bar{K} pi pi invariant masses into bar{K}^* pi and rho K modes, the channels to which these two resonances couple most strongly, predicting that these modes peak at different energies and have different widths. These measurements should shed light on the existence of these two K_1 states. In addition, we have gone one step further making a comparison with experimental results of three meson decay channels, letting the vector mesons of our approach decay into pseudoscalars, and we find an overall good agreement with experiment.

Massive neutron stars with a color superconducting quark matter core

We construct the equation of state for high-density neutron star matter at zero temperature using the two-flavor Nambu--Jona-Lasinio (NJL) model as an effective theory of QCD. We build nuclear matter, quark matter, and the mixed phases from the same NJL Lagrangian, which has been used to model free and in-medium hadrons as well as nuclear systems. A focus here is to determine if the same coupling constants in the scalar diquark and vector meson channels, which give a good description of nucleon structure and nuclear matter, can also be used for the color superconducting high-density quark matter phase. We find that this is possible for the scalar diquark (pairing) interaction, but the vector meson interaction has to be reduced so that superconducting quark matter becomes the stable phase at high densities. We compare our equation of state with recent phenomenological parametrizations based on generic stability conditions for neutron stars. We find that the maximum mass of a hybrid star, with a color superconducting quark matter core, exceeds $2.01\ifmmode\pm\else\textpm\fi{}0.04\phantom{\rule{0.16em}{0ex}}{M}_{\ensuremath{\bigodot}}$, which is the value of the recently observed massive neutron star PSR $\text{J0348}+0432$. The mass-radius relation is also consistent with gravitational wave observations (GW170817).

Sensitivity of the excitation functions of collective flow to relativistic scalar and vector meson interactions in the relativistic quantum molecular dynamics model RQMD.RMF

Relativistic quantum molecular dynamics with scalar and vector interactions based on the relativistic mean meson field theory, RQMD.RMF, is developed.It is implemented into the microscopic transport code JAM.The sensitivity of the directed and of the elliptic proton flow in high energy heavy-ion collisions on the stiffness of the RMF equation of state (EoS) is examined. These new calculations are compared to experimental data at mid-central Au + Au collisions in the beam energy range $2.5 < \sqrt{s_{NN}} < 20$ GeV. This new RQMD model with the relativistic mean field scalar and vector meson interactions does describe consistently, with one RMF parameter set,the beam energy dependence of both the directed flow and the elliptic flow,from SIS18 to AGS and RHIC BES-II energies, $\sqrt{s_{NN}}< 10$ GeV.There are different sensitivities of these different kinds of flow to the EoS: elliptic flow is most sensitive to the nuclear incompressibility constant,at the moderate beam energies $\sqrt{s_{NN}}<3$ GeV,whereas the directed flow is most sensitive to the effective baryon mass at saturation density at $3< \sqrt{s_{NN}}<5 $ GeV. Matters abruptly change in the next higher energy range,$\sqrt{s_{NN}}\gtrsim 10-20$ GeV:the directed flow data show a double change of sign of the slope of $v_1$, inverting twice in this energy range,in sudden contradiction to the RQMD.RMF calculation for a monotonous, stiff EoS. This surprising oscillating behavior,a double change of sign of the $v_1$ slope, points to the appearance of a hitherto unknown first-order phase transition in excited QCD matter at high baryon densities in mid-central Au + Au collisions.

Axial Vector-Meson–Nucleon Interaction Constant in the AdS/QCD Soft Wall Model

This work investigates the interaction of an axial vector-meson with nucleons in the AdS/QCD soft wall model. The axial vector fields have been determined inside the anti-de Sitter (AdS) space with the help of gauge fields with left and right chiral symmetries. In addition, a pseudoscalar field has been introduced inside the AdS space to break the chiral symmetry. A Lagrangian for these fields has been introduced inside the AdS space and the profile functions which are solutions of the equation of motion have been found. In accordance with AdS/CFT, the interaction constant of the axial vector-meson with the nucleons has been obtained as an integral over the additional dimension. The main task of this work was to find numerical values of the interaction constant of the axial vector-meson with the nucleons in the AdS/QCD soft wall model. With the help of the computer program Mathematica 7, these values were determined. A comparison of the theoretical and experimental data has revealed significant agreement of the results.

Modeling interactions of photons with pseudoscalar and vector mesons

We model interaction of photons, pseudoscalars and vector mesons within the resonance chiral symmetric theory with the SU(3) breaking. The couplings of the model are fitted to the experimental data. Within the developed model we predict the light-by-light contributions to the muon anomalous magnetic moment $a_{\mu}^P = (82.8 \pm 3.4)\times 10^{-11}$. The error covers also the model dependence within the class of models considered in this paper. The model was implemented into the Monte Carlo event generator Ekhara to simulate the reactions $e^+e^-\to e^+e^- P$, $P=\pi^0,\eta,\eta'$ and into the Monte Carlo event generator Phokhara to simulate the reactions $e^+e^-\to P\gamma(\gamma)$.

Charm-beauty meson bound states from B(B*)D(D*) and B(B*)D¯(D¯*) interaction

We evaluate the s-wave interaction of pseudoscalar and vector mesons with both charm and beauty to investigate the possible existence of molecular $BD$, $B^*D$, $BD^*$, $B^*D^*$, $B\bar D$, $B^*\bar D$, $B\bar D^*$ or $B^* \bar D^*$ meson states. The scattering amplitude is obtained implementing unitarity starting from a tree level potential accounting for the dominant vector meson exchange. The diagrams are evaluated using suitable extensions to the heavy flavor sector of the hidden gauge symmetry Lagrangians involving vector and pseudoscalar mesons{, respecting heavy quark spin symmetry}. We obtain bound states at energies above 7 GeV for $BD$ ($J^P=0^+$), $B^*D$ ($1^+$), $BD^*$ ($1^+$) and $B^*D^*$ ($0^+$, $1^+$, $2^+$), all in isospin 0. For $B\bar D$ ($0^+$), $B^*\bar D$ ($1^+$), $B\bar D^*$ ($1^+$) and $B^*\bar D^*$ ($0^+$, $1^+$, $2^+$) we also find similar bound states in $I=0$, but much less bound, which would correspond to exotic meson states with $\bar b$ and $\bar c$ quarks, and for the $I=1$ we find a repulsive interaction. We also evaluate the scattering lengths in all cases, which can be tested in current investigations of lattice QCD.

The impact of vector mesons polarization on meson-nucleon interaction

Production of unstable particles off nuclei allows to determine the total cross section of the unstable particle interaction with nucleons. The interaction of vector mesons V(ρ, ω, ϕ) with nucleons are defined by a set of amplitudes corresponding to the transverse polarization of the vector meson (helicity λ = ±1) meson or longitudinal one (λ = 0). Whereas the total cross section for the interaction of the transversely polarized vector meson with nucleon σ T = σ(VTN) can be extract from the coherent photoproduction, measurements of vector meson interaction with nucleon σL= σ(VLN).As a good tool for such investigation we proposed the photoproduction of ω mesons on the set of nuclei in the incoherent region. Such experiment can be done using the feasibility of the new experiment GlueX at Jefferson Lab, designed to study the photoproduction of mesons in a large beam energy range up to 12 GeV.

Interaction of the vector-meson octet with the baryon octet in effective field theory

We analyze the constraint structure of the interaction of vector mesons with baryons using the classical Dirac constraint analysis. We show that the standard interaction in terms of two independent SU(3) structures is consistent at the classical level. We then require the self-consistency condition of the interacting system in terms of perturbative renormalizability to obtain relations for the renormalized coupling constants at the one-loop level. As a result we find a universal interaction with one coupling constant which is the same as in the massive Yang-Mills Lagrangian of the vector-meson sector.

Photoproduction of the f2(1270) resonance

We have performed a calculation of the $\gamma p \to \pi^+ \pi^- p$ reaction, where the two pions have been separated in $D$-wave producing the $f_2(1270)$ resonance. We use elements of the local hidden gauge approach that provides the interaction of vector mesons in which the $f_2(1270)$ resonance appears as a $\rho$-$\rho$ molecular state in $L=0$ and spin 2. The vector meson dominance, incorporated in the local hidden gauge approach converts a photon into a $\rho^0$ meson and the other meson connects the photon with the proton. The picture is simple and has no free parameters, since the parameters of the theory have been constrained in the previous study of the vector-vector states. In a second step we introduce new elements, not present in the local hidden gauge approach, adapting the $\rho$ propagator to Regge phenomenology and introducing the $\rho NN$ tensor coupling. We find that both the differential cross section as well as the $t$ dependence of the cross section are in good agreement with the experimental results and provide support for the molecular picture of the $f_2(1270)$ in the first baryonic reaction where it has been tested.

B¯0andB¯s0decays intoJ/ψandf0(1370),f0(1710),f2(1270),f2′(1525),K2*(1430)

We make predictions for the ratios of branching fractions of ${\overline{B}}^{0}$ and ${\overline{B}}_{s}^{0}$ decays into $J/\ensuremath{\psi}$ and the scalar mesons ${f}_{0}(1370)$, ${f}_{0}(1710)$ or tensor mesons ${f}_{2}(1270)$, ${f}_{2}^{\ensuremath{'}}(1525)$, ${K}_{2}^{*}(1430)$. The theoretical approach is based on results of chiral unitary theory where these resonances are shown to be generated from the vector meson--vector meson interaction. Eight independent ratios can be predicted, and comparison is made with the recent data on ${\overline{B}}_{s}^{0}$ decay into $J/\ensuremath{\psi}{f}_{2}^{\ensuremath{'}}(1525)$ versus the ${\overline{B}}_{s}^{0}$ decay into $J/\ensuremath{\psi}{f}_{2}(1270)$.

Pseudoscalar meson and vector meson interactions and dynamically generated axial-vector mesons

The axial-vector mesons $a_1(1260)$, $b_1(1235)$, $f_1(1285)$, $h_1(1170)$, $h_1(1380)$, and $K_1(1270)$ are dynamically generated in the unitized chiral perturbation theory. Such a picture has been tested extensively in the past few years. In this work, we calculate the interaction kernel up to $\mathcal{O}(p^2)$ and study the impact on the dynamically generated axial-vector states. In anticipation of future lattice QCD simulations, we calculate the scattering lengths and the pole positions as functions of the pion mass, with the light-quark mass dependence of the kaon, the eta, and the vector mesons determined by the $n_f=2+1$ lattice QCD simulations of the PACS-CS Collaboration.

N AND Δ HIDDEN-CHARM RESONANCES WITH HEAVY-QUARK SPIN SYMMETRY

We study N and Δ hidden-charm baryon resonances that are generated dynamically from the s-wave interaction of pseudoscalar and vector mesons with 1/2+ and 3/2+ baryons. We use a unitary coupled-channels model that fulfills heavy-quark spin symmetry and respects spin-flavor symmetry in the light sector. We predict seven N-like and five Δ-like states with masses around 4 GeV, most of them as bound states. Some of these states form heavy-quark spin multiplets, which are almost degenerate in mass.

N*'s AND Δ's GENERATED IN VECTOR, PSEUDOSCALAR MESON-BARYON SYSTEMS

We have recently studied coupled channel interactions of vector and pseudoscalar mesons with octet baryons having total strangeness null and spin-parity 1/2-. We, thus, considered πN, ηN, KΛ, KΣ, ρN, ωN, ϕN, K*Λ, and K*Σ with total isospin 1/2 and 3/2. The interactions between pseudoscalar mesons and baryons are obtained by using the Weinberg-Tomozawa theorem. For the case of vector mesons, we calculate s-, t-, u-exchange diagrams and a contact term. The subtraction constants, required to calculate the loop-function in the scattering equations, are constrained by fitting the available experimental data on some of the reactions with pseudoscalar meson-baryon final states. We end up finding resonances which can be related to N*(1535), N*(1650) (with a double pole structure), N*(1895) and Δ(1620). We conclude that these resonances can be, at least partly, interpreted as dynamically generated resonances and that the vector mesons play an important role in determining the dynamical origin of the low-lying N* and Δ states.

VECTOR-BARYON DYNAMICS IN γN → K0Σ REACTIONS

A coupled channel model for the interaction of vector mesons with baryons is employed in the study of the γp → K0Σ+ reaction around the K*Λ and K*Σ thresholds, where the recent CBELSA/TAPS cross section shows a sudden drop and the differential cross section experiences a transition from a forward-peaked distribution to a flat one. A delicate interference between amplitudes having K*Λ and K*Σ intermediate states is found. The sharp downfall is dictated by the presence of a N* resonance produced by our model, a feature that we have employed to infer its properties. Predictions for the complementary γn → K0Σ0 reaction are also given.

Vector-meson dominance and photonuclear interactions at superhigh energies

It is shown that experimental data on the electromagnetic structure functions of a nucleon in the kinematic region of low x can be described in terms of a two-component approach in which the nonperturbative part of photon-nucleon interaction is described in terms of a updated variant of the generalized model of vector dominance that includes the radial excitations of mesons and off-diagonal elements of the matrix of meson-nucleon scattering. The perturbative component is described using the color-dipole model.

Implications of the measurement of pulsars with two solar masses for quark matter in compact stars and heavy-ion collisions: A Nambu–Jona-Lasinio model case study

The precise measurement of the high masses of the pulsars PSR J1614-2230 (M_{1614}=1.97 +- 0.04 solar masses) and PSR J0348-0432 (M_{0348}=2.01 +- 0.04 solar masses) provides an important constraint for the equation of state of cold, dense matter and is suited to give interesting insights regarding the nature and existence of the possible phase transition to deconfined quark matter in the cores of neutron stars. We analyze the stability and composition of compact star sequences for a class of hybrid nuclear - quark-matter equations of state. The quark matter phase is described in the framework of a standard color superconducting 3-flavor Nambu-Jona-Lasinio model and the hadronic phase is given by the Dirac-Brueckner-Hartree-Fock equation of state for the Bonn-A potential. The phase transition is obtained by a Maxwell construction. Within this model setup we aim to constrain otherwise not strictly fixed parameters of the NJL model, namely the coupling strengths in the vector meson and diquark interaction channels. We perform this investigation for two different parameterizations characterized by a different scalar coupling constant. The analysis of flow data obtained in heavy-ion collisions resulted in a further constraint which we account for in our discussion. Massive hybrid stars with extended quark matter cores can be obtained in accordance with all of the considered constraints.