The contribution of the hadronic continuum in the QCD sum rule calculation of the parameters entering in pseudoscalar meson mixing is evaluated by making use of simple integration kernels tailored in order to practically eliminate the contribution of the hadronic continuum. This approach avoids the arbitrariness and instability inherent to previous sum rule calculations. An independent evaluation of the mixed quark gluon condensate $\left\langle QGC\right\rangle =$$\left\langle g\bar{q}σ_{μν}\frac{λ^{a}}{2}G_{μν}^{a}q\right\rangle $ which enters in the calculation is presented as well as the calculation of the K-meson decay constant $f_{K}$ to five loops.
We consider the production of a Higgs pseudoscalar accompanied by two jets in hadronic collisions. We work in the limit that the top quark is much heavier than the Higgs pseudoscalar and use an effective Lagrangian for the interactions of gluons with the pseudoscalar. We compute the amplitudes involving: 1) four gluons and the pseudoscalar, 2) two quarks, two gluons and the pseudoscalar and 3) four quarks and the pseudoscalar. We find that the pseudoscalar amplitudes are nearly identical to those for the scalar case, the only differences being the overall size and the relative signs between te…
The contribution of pseudoscalar pole diagrams to the hadronic light-by-light corrections of order alpha^3 E_F to the ground state hyperfine splitting in hydrogenic atom is calculated in the pseudoscalar pole terms approximation. The vector dominance model for the form factor of the transition of a pseudoscalar meson into two photons is used. With the account of new experimental data on the cross sections sigma (e^+e^-\to ρ, ω\to π^0(η)γ) in the SND and CMD-2 experiments some other hadronic corrections to the muonium hyperfine splitting are calculated.
The pseudoscalar pole contribution is the dominant source of the $ {\cal O}(α^3) $ hadronic light-by-light scattering effect in muon $g - 2$. We have examined this contribution taking account of the off-shell structure of the pseudoscalar-photon-photon anomaly vertex deduced from available experimental data. Our work leads to an improved estimate, $ -79.2 (15.4) \times 10^{-11}$, for the total hadronic light-by-light scattering contribution to the muon $g - 2$.
The evaluation of the numerically dominant pseudoscalar-pole contribution to hadronic light-by-light scattering in the muon g-2 involves the pseudoscalar-photon transition form factor F_{P gamma^* gamma^*}(-Q_1^2, -Q_2^2) with P = pi^0, eta, eta^\prime and, in general, two off-shell photons with spacelike momenta Q_{1,2}^2. We determine which regions of photon momenta give the main contribution for hadronic light-by-light scattering. Furthermore, we analyze how the precision of future measurements of the single- and double-virtual form factor impacts the precision of a data-driven estimate of …
In this work, we present our recent results on a new and alternative data-driven determination for the hadronic light-by-light pseudoscalar-pole contribution to the muon $(g-2)$. Our approach is based on Canterbury approximants, a rational approach to describe the required transition form factors, which provides a systematic and model-independent framework beyond traditional large-$N_c$ approaches. As a result, we obtain a competitive determination with errors according to future $(g-2)$ experiments including, for the first time, a well-defined systematic uncertainty.
Since b quark mass is not asymptotically large, chirally enhanced corrections which arise from twist-3 wave functions may be important in B decays. We thus evaluate the hadronic matrix elements with the emitted meson described by leading twist and twist-3 distribution amplitudes $Φ_p(x)$. After summing over the four "vertex correction" diagrams, we obtain the results with infrared finiteness which shows that chirally enhanced corrections arise from $Φ_p(x)$ can be consistently included in QCD factorization. We also briefly discuss the contributions from "hard spectator" diagrams.
The light-by-light contribution to the anomalous magnetic moment of muon (g-2)_μ from the hadronic exchanges in the neutral pseudoscalar meson channel is calculated in the nonlocal chiral quark model. The full kinematic dependence of the meson-two-photon vertices on the virtualities of the mesons and photons is taken into account. The status of various phenomenological and QCD short-distance constraints is discussed and the comparison with the predictions of other models is performed. It is demonstrated that the effect of the full kinematic dependence in the meson-photon vertices is to reduce …
We have performed a numerical analysis of branching ratios and direct CP-asymmetries of B meson decays to two light pseudoscalar nonets with deltaS=1 using QCD improved factorization. The parameters related to B meson including its semileptonic form factors, strange quark mass and the CKM phase angle have been varied over a limited range and phenomenological parameters used to parameterize divergences in hard spectator scattering and weak annihilation have been varied over a wide range simultaneously with an aim to achieve a fit of branching ratios and some direct CP-asymmetries. A good fit fo…
We have employed the framework of Bethe-Salpeter equation under covariant instantaneous ansatz to calculate leptonic decay constants of unequal mass pseudoscalar mesons like pi, K, D, Ds and B and radiative decay constants of neutral pseudoscalar mesons like pi and etac in two photon decays of these mesons. In the Dirac structure of hadronic BS wave function, the covariants are incorporated from their complete set in accordance with a recently proposed power counting rule, order-by-order in powers of inverse of meson mass. The decay constants are calculated with the incorporation of both Leadi…
The evaluation of the numerically dominant pseudoscalar-pole contribution to hadronic light-by-light scattering in the muon g-2 involves the pseudoscalar-photon transition form factor F_{P gamma^* gamma^*}(-Q_1^2, -Q_2^2) with P = pi^0, eta, eta^\prime and, in general, two off-shell photons with spacelike momenta Q_{1,2}^2. We show, in a largely model-independent way, that for pi^0 (eta, eta^\prime) the region of photon momenta below about 1 (1.5) GeV gives the main contribution to hadronic light-by-light scattering. We then discuss how the precision of current and future measurements of the s…
In this work, we evaluate the contributions of the hadronic loops to the amplitudes of $J/ψ\to PV$ where $P$ and $V$ denote light pseudoscalar and vector mesons respectively. By fitting data of two well measured channels of $J/ψ\to PV$, we obtain the contribution from the pure OZI process to the amplitude which is expressed by a phenomenological quantity $|\mathcal{G}^{PV}_{S}|$, and a parameter $α$ existing in the calculations of the contribution of hadronic loops. In terms of $α$ and $|\mathcal{G}^{PV}_{S}|$, we calculate the branching ratios of other channels and get results which are reaso…
We study two-body charmless hadronic decays of $B$ mesons to a pseudoscalar meson ($P$) and a tensor meson ($T$) in the frameworks of both flavor SU(3) symmetry and generalized factorization. Certain ways to test validity of the generalized factorization are proposed, based on the flavor SU(3) analysis. We present a set of relations between a flavor SU(3) amplitude and a corresponding amplitude in the generalized factorization which bridge both approaches in $B \to PT$ decays. The branching ratios and CP asymmetries are calculated using the \emph{full} effective Hamiltonian including all the \…
Recent works have discussed the violation of factorization and universality in hadronic hard scattering processes aimed at measurements of T-odd distributions. We use simple arguments to show that it is possible to restore an approximate factorization involving T-odd contributions if the factorization breaking interactions present a frequency spectrum dominated by by a narrow and regular peak whose maximum value corresponds to a respected factorization.
We study the hadronic vacuum polarization in the resonance energy region, using the framework given by the Resonance Effective Theory of QCD. We consider the incorporation of vector-pseudoscalar meson loops that give, inclusively, three and four pseudoscalar meson cuts. After resummation we achieve a QCD-based inclusive parameterization of the correlator, hence of the hadronic cross-section in the energy region populated by resonances.
We present preliminary results from our calculation of the pseudoscalar transition form factors of the $η$ and $η'$ mesons using staggered quarks on $N_f=2+1+1$ gauge ensembles generated by the Budapest-Marseille-Wuppertal collaboration. These transition form factors are an important input for the hadronic light-by-light contribution to the muon $(g-2)$. We first elaborate on the extraction of the masses of the $η$ and $η'$ mesons, that mix under the dynamics of QCD. Thereafter, we show our preliminary results for the pseudoscalar transition form factors, focusing on the $η$ meson in the absen…
We report on our progress toward the computation of the $π^0$, $η$ and $η^{\prime}$ transition form factors using staggered quarks on $N_f=2+1+1$ gauge ensembles generated by the Budapest-Marseille-Wuppertal collaboration. These form factors are essential ingredients to evaluate the pseudoscalar-pole contributions to the hadronic light-by-light scattering in the muon $g-2$. Preliminary results for the pseudoscalar-pole contributions are presented, at finite lattice spacing, for all three light mesons.
In semi-leptonic and other weak decays of mesons, the hadronic matrix elements of the operators in the weak Hamiltonian are parametrized by standard sets of independent, Lorentz invariant, form factors. For the case of pseudoscalar to vector meson transitions, it has been shown that a Quark Model description leads to relations between some of the form factors. Here, I give an alternate, and more general, proof of those relations and thus confirm that, in the Quark Model, not all the form factors for pseudoscalar to vector meson transitions are independent. As an application of this result, a Q…
We study exclusive production of scalar $χ_{c0}\equiv χ_c(0^{++})$ and pseudoscalar $η_c$ charmonia states in proton-proton collisions at the LHC energies. The amplitudes for $gg \to χ_{c0}$ as well as for $gg \to η_c$ mechanisms are derived in the $k_{T}$-factorization approach. The $p p \to p p η_c$ reaction is discussed for the first time. We have calculated rapidity, transverse momentum distributions as well as such correlation observables as the distribution in relative azimuthal angle and $(t_1,t_2)$ distributions. The latter two observables are very different for $χ_{c0}$ and $η_c$ case…
The basic ideas of kt-factorization and CCFM parton evolution is discussed. The unintegrated gluon densities, obtained from CCFM fits to the proton structure function data at HERA are used to predict hadronic final state cross sections like jet production at HERA, but also comparisons with recent measurements of heavy quark production at the Tevatron are presented. Finally, the kt-factorization approach is applied to Higgs production at high energy hadron hadron colliders and the transverse momentum spectrum of Higgs production at the LHC is calculated.
We have studied the $P\toγ^\starγ^\star$ form factor in Resonance Chiral Theory, with $P = π^0,η,η'$, to compute the contribution of the pseudoscalar pole to the hadronic light-by-light piece of the anomalous magnetic moment of the muon. In this work we allow the leading $U(3)$ chiral symmetry breaking terms, obtaining the most general expression for the form factor of order $\mathcal{O}(m_P^2)$. The parameters of the Effective Field Theory are obtained by means of short distance constraints on the form factor and matching with the expected behavior from QCD. Those parameters that cannot be fi…
Entangled pseudoscalar neutral meson pairs have been used in studying CP violation and searching CPT violation, but almost all the previous works concern $C=-1$ entangled state. Here we consider $C=+1$ entangled state of pseudoscalar neutral mesons, which is quite different from $C=-1$ entangled state and provides complementary information on symmetry violating parameters. After developing a general formalism, we consider three kinds of decay processes, namely, semileptonic-semileptonic, hadronic-hadronic and semileptonic-hadronic processes. For each kind of processes, we calculate the integra…
I review the meaning of ``QCD factorization'' in hadronic two-body B decays and then discuss recent results of theoretical (rather than phenomenological) nature: the proof of factorization at two loops; the identification of ``chirally enhanced'' power corrections; and the role of annihilation contributions.
We consider the branching ratios and CP asymmetry in the B meson decays into two pseudoscalar mesons in the generalized factorization approximation. We also investigate the possible effects of the enhanced chromomagnetic interaction b --> s g on these exclusive B meson decays that was suggested as a possible solution to the semileptonic branching ratio of B mesons, the missing charm puzzle and the large B --> η^{'} + X_s. We finds that such enhanced b --> s g interaction degrades the agreement between the data and the model predictions for B meson decays into two light mesons in the generalize…
We have studied the $P\toγ^\starγ^\star$ form factor in Resonance Chiral Theory, with $P = π^0ηη'$, to compute the contribution of the pseudoscalar pole to the hadronic light-by-light piece of the anomalous magnetic moment of the muon. In this work we allow the leading $U(3)$ chiral symmetry breaking terms, obtaining the most general expression for the form factor up to $\mathcal{O}(m_P^2)$. The parameters of the Effective Field Theory are obtained by means of short distance constraints on the form factor and matching with the expected behavior from QCD. Those parameters that cannot be fixed i…
We present a new analysis of two-jet event shape distributions in soft collinear effective theory. Extending previous results, we observe that a large class of such distributions can be expressed in terms of vacuum matrix elements of operators in the effective theory. We match these matrix elements to the full theory in the two-jet limit without assuming factorization of the complete set of hadronic final states into independent sums over partonic collinear and soft states. We also briefly discuss the relationship of this approach to diagrammatic factorization in the full theory.
In the present investigation, we evaluate the in-medium partial decay widths of exited states $ψ$(4040) and $Y$(4008) decaying to the pairs of non-strange pseudoscalar $D \bar{D}$ mesons, strange pseudoscalar $D_s \bar{D}_s$ mesons, non-strange vector $D^* \bar{D}^*$ meson and pseudoscalar-vector $D \bar{D}^*$ mesons using $^3P_0$ model. The in-medium effects are incorporated through the in-medium masses of daughter mesons (calculated using the chiral SU(3) model and QCD sum rule approach in our previous works). We consider $ψ$(4040) and $Y$(4008) states as 3$^3S_1$ states and observe the in-m…
Because quarks in hadronic states are subjected to strong QCD forces, it is not straight-forward to apply calculation obtained at the quark level to physical processes involving hadrons. In this paper we present a new approach to treat the semileptonic decays of pseudoscalar mesons. At the quark level, the process is straightforward. However, when we fold the quark-level process to the meson decay process, the complication from QCD effects come in. We make the fundamental assumption that the vertex of type M-q-qbar can be approximated by an effective constant gamma-5 coupling. With this assump…
In this paper, we investigate phenomenologically two-body weak decays of the bottom mesons emitting pseudoscalar and tensor mesons. Decay amplitudes are obtained using the factorization scheme in the improved ISGW II model. Branching ratios for the CKM-favored and CKM-suppressed decays are calculated.
We compute the next-to-next-to-leading order (NNLO) QCD corrections to the hadronic decay rates of the pseudoscalar quarkonia, at the lowest order in velocity expansion. The validity of NRQCD factorization for inclusive quarkonium decay process, for the first time, is verified to relative order $α_s^2$. As a byproduct, the renormalization group equation (RGE) of the leading NRQCD 4-fermion operator ${\cal O}_1({}^1S_0)$ is also deduced to this perturbative order. By incorporating this new piece of correction together with available relativistic corrections, we find that there exists severe ten…
We review recent advances in the theory of strong-interaction effects and final-state interactions in hadronic weak decays of heavy mesons. In the heavy-quark limit, the amplitudes for most nonleptonic, two-body B decays can be calculated from first principles and expressed in terms of semileptonic form factors and light-cone distribution amplitudes. We summarize the main features of this novel QCD factorization and discuss its phenomenological applications to B -> D^(*) L decays (with L a light meson), and to the rare charmless decays B -> pi K and B -> pi pi.
Mass dependences of the total production rates per hadronic Z decay of all light-flavour hadrons measured so far at LEP are extrapolated to the zero mass limit (m=0) using phenomenological laws of hadron production related to the spin, isospin, strangeness content and mass of the particles. The vector-to-pseudoscalar and meson-to-baryon ratios at m=0 are found to be: rho^+ / 3 pi^+ = 1.2 +/- 0.3 and pi^+ / p = 2.9 +/- 0.3, in good agreement with the predictions of quark combinatorics.
Despite recent developments, there are a number of conceptual issues on the hadronic light-by-light (HLbL) contribution to the muon $(g-2)$ which remain unresolved. One of the most controversial ones is the precise way in which short-distance constraints get saturated by resonance exchange, particularly in the so-called Melnikov-Vainshtein (MV) limit. In this paper we address this and related issues from a novel perspective, employing a warped five-dimensional model as a tool to generate a consistent realization of QCD in the large-$N_c$ limit. This approach differs from previous ones in that …
In this paper, the twist-3 two parton corrections in charmless $B\to PP$ decays are shown to be factorizable under the QCD factorization approach. The factorizability of the twist-3 two parton corrections is constructed on the following findings. Under the energetic meson limit, the pseudoscalar distribution amplitude for a light pseudoscalar meson is allowed to be non-constant by the equations of motion for the quark. The non-constant pseudoscalar distribution amplitude is then used to regularize the end-point divergences in the hard spectator corrections at twist-3 order. By retaining the mo…
The $π^0$, $η$, and $η^\prime$ transition form factors in the space-like region are analyzed at low and intermediate energies in a model-independent way through the use of rational approximants. Slope and curvature parameters as well as their values at infinity are extracted from experimental data. These results are suited for constraining hadronic models such as the ones used for the hadronic light-by-light scattering piece of the anomalous magnetic moment of the muon, and for the mixing parameters of the $η- η^\prime$ system.
The cross sections for $J/ψ$ absorption by $π$ and $ρ$ mesons are studied in a meson-exchange model that includes not only pseudoscalar-pseudoscalar-vector-meson couplings but also three-vector-meson and four-point couplings. We find that they are much larger than in a previous study where only pseudoscalar-pseudoscalar-vector-meson couplings were considered. Including form factors at interaction vertices, the $J/ψ$ absorption cross sections $σ_{πψ}$ and $σ_{ρψ}$ are found to have values on the order of 7 mb and 3 mb, respectively. Their thermal averages in hadronic matter at temperature T=150…
Recent theoretical investigations of two-body hadronic B decays have provided justification for the use of the factorization ansatz to evaluate the B decay matrix elements. Motivated by this, we present simplified formulae for a wide range of B decays into the lowest mass pseudoscalar and vector mesons. These formulae, valid in the heavy quark limit, involve a reduced set of soft QCD parameters and, although resulting in some loss of accuracy, should still provide an adequate and transparent tool with which to confront data for some time to come. Finally, we confront these formulae with data o…
We review recent advances in the theory of strong-interaction effects and final-state interactions in hadronic weak decays of heavy mesons. In the heavy-quark limit, the amplitudes for most nonleptonic, two-body B decays can be calculated from first principles and expressed in terms of semileptonic form factors and light-cone distribution amplitudes. We summarize the main features of this novel QCD factorization and discuss its phenomenological applications to B->D^(*)+L decays (with L a light meson), and to the rare charmless decays B->pi+K and B->pi+pi.
Third QED order hadronic light-by-light (LBL) contributions $a_μ^{LBL}(M)$ to the anomalous magnetic moment of the muon $a_μ^{had}$ from the pole terms of scalar $σ$, $a_0(980)$ and pseudoscalar $π^0$, $η$, $η'$ mesons (M) in the framework of the linearized extended Nambu-Jona-Lasinio model are evaluated. The off-shell structure of the photon-photon-meson vertices is taken into account by means of constituent quark triangle loops. The mass of the quark is taken to be $m_u=m_d=m_q=(280 \pm 20)$ MeV. The unknown strong coupling constants of $π^0, η, η'$ and $a_0$ mesons with quarks are evaluated…
In standard Regge theory with a pomeron intercept a(0)=1+ε, the contribution of the tripe-pomeron amplitude to the t=0 differential cross section for single diffraction dissociation has the form dσ/dM^2(t=0) \sim s^{2ε}/(M^2)^{1+ε}. For ε>0, this form, which is based on factorization, does not scale with energy. From an analysis of p-p and p-pbar data from fixed target to collider energies, we find that such scaling actually holds, signaling a breakdown of factorization. Phenomenologically, this result can be obtained from a scaling law in diffraction, which is embedded in the hypothesis of po…
The decays of $B$ mesons to a pair of charmless pseudoscalar mesons ($PP$ decays) or to a vector and pseudoscalar meson ($VP$ decays) have been analyzed within the framework of flavor SU(3) symmetry and the Kobayashi-Maskawa mechanism of CP violation. Separate $PP$ and $VP$ fits proved to be successful in describing the experimental data (branching ratios, CP asymmetries and time-dependent parameters). Decay magnitudes and relative weak and strong phases have been extracted from the fits. Values of the weak phase $γ$ were found to be consistent with the current indirect bounds from other analy…
We study forward dijet production in dilute-dense hadronic collisions. By considering the appropriate limits, we show that both the transverse-momentum-dependent (TMD) and the high-energy factorization formulas can be derived from the Color Glass Condensate framework. Respectively, this happens when the transverse momentum imbalance of the dijet system, $k_t$, is of the order of either the saturation scale, or the hard jet momenta, the former being always much smaller than the latter. We propose a new formula for forward dijets that encompasses both situations and is therefore applicable regar…
We investigate the masses of the pseudoscalar ($D$($D^0$, $D^+$), $\bar{D}$($\bar{D^0}$, $D^-$) and vector open charm mesons ($D^*$($D^{*0}$, $D^{*+}$), ${\bar{D}}^*$(${\bar{D}}^{*0}$, $D^{*-}$) as well as the pseudoscalar ($η_c(1S)$, $η_c(2S)$) and the vector charmonium states ($J/ψ$, $ψ(2S)$, $ψ(1D)$) 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 $δ$) are investigated in a chiral effective model. Moreover, …
We compare results of $k_t$-factorization approach and next-to-leading order collinear-factorization approach for photon-jet correlations in $pp$ and $p \bar p$ collisions at RHIC, Tevatron and LHC energies. We discuss correlations in azimuthal angle as well as in two-dimensional space of transverse momenta of photon and jet. Different unintegrated parton distributions (UPDF) are included in the $k_t$-factorization approach. The results depend on UPDFs used. The results of NLO collinear-factorization are shown for comparison.
We propose a QCD-based model for calculation of the non-perturbative corrections to the factorization approximation in the decays of heavy mesons. In the framework of the model, factorization in pseudoscalar transitions holds exactly at the leading order leaving the opportunity to calculate non-leading corrections consistently.
The Drell-Yan hadronic tensor for electromagnetic (EM) current is calculated in the Sudakov region $s\gg Q^2\gg q_\perp^2$ with ${1\over Q^2}$ accuracy, first at the tree level and then with the double-log accuracy. It is demonstrated that in the leading order in $N_c$ the higher-twist quark-quark-gluon TMDs reduce to leading-twist TMDs due to QCD equation of motion. The resulting tensor for unpolarized hadrons is EM gauge-invariant and depends on two leading-twist TMDs: $f_1$ responsible for total DY cross section, and Boer-Mulders function $h_1^\perp$. The order-of-magnitude estimates of ang…
Two body nonleptonic weak decays of bottom mesons to a pseudoscalar meson and an axial-vector meson involving charmed states are studied using the non-relativistic quark model. We calculate the branching ratios of these decays by employing the factorization hypothesis. Obtained results are in good agreement with the existing experimental data. We also calculated the branching ratios in the light of heavy quark symmetry constraints and compared with the exiting theoretical analyses.
We present a relativistic constituent quark model to analyze the mass spectrum and hadronic properties of radially excited u and d quark sector mesons. Using a simple Gaussian function as a trial wave function for the variational principle of a QCD motivated Hamiltonian, we obtain the mass spectrum consistent with the experimental data. To do the same for several observables such as decay constants and form factors, it seems necessary to include both Dirac and Pauli form factors on the level of constituent quarks. Taking into account the quark form factors, we thus present the generalized form…
I briefly introduce the theoretical frameworks for studies of two-body hadronic $B$ meson decays, which include the factorization assumption, the QCD-improved factorization, the perturbative QCD, the soft-collinear effective theory, the light-cone QCD sum rules, and the quark-diagram parametrization.
We study the decay $B^\pm\to ϕK^{\ast\pm}$, followed by the decay of the outgoing vector mesons into two pseudoscalars. The analysis of angular distributions of the decay products is shown to provide useful information about the annihilation contributions and possible tests of factorization.
The electromagnetic form factors of light and heavy pseudoscalar mesons are calculated within two covariant constituent-quark models, a light-front and a dispersion relation approach. We investigate the details and physical origins of the model dependence of various hadronic observables: the weak decay constant, the charge radius and the elastic electromagnetic form factor.
We propose studying the mechanism of factorization in exclusive decays of the form B->D(*)X by examining the differential decay rate as a function of the invariant mass of the light hadronic state X. If factorization works primarily due to the large N_c limit then its accuracy is not expected to decrease as the X invariant mass increases. However, if factorization is mostly a consequence of perturbative QCD then the corrections should grow with the X invariant mass. Combining data for hadronic tau decays and semileptonic B decays allows tests of factorization to be made for a variety of final …
We compare results of $k_t$-factorization approach and next-to-leading order collinear-factorization approach for photon-jet correlations in $pp$ and $p \bar p$ collisions at RHIC, Tevatron and LHC energies. We discuss correlations in azimuthal angle between photon and jet as well as correlations in two-dimensional space of photon and jet transverse momenta. Different unintegrated gluon/parton distributions are used in the $k_t$-factorization approach. The results depend on UGDF/UPDF used. The collinear NLO $2 \to 3$ contributions dominate over $k_t$-factorization cross section at small relati…
We make use of the Nambu-Jona-Lasinio (NJL) formalism and real-time finite-temperature field theory to calculate hadronic current correlation functions in the deconfined phase of quantum chromodynamics (QCD). We consider both pseudoscalar and vector currents and compare our results with those obtained in lattice simulations of QCD. Our results are similar to those obtained in the lattice simulations for $T=1.5 T_c$, where $T_c$ is the temperature of the confinement-deconfinement transition. For $T=3.0 T_c$ our results do not exhibit the resonances obtained from the lattice simulations. However…
