\begin{longtable}{p{0.15\textwidth}|b{0.425\textwidth}|b{0.425\textwidth}}
\caption{Research areas, their top-words, and their correlation with a standard classification (PACS).}
\label{table:research_areas}\\
\toprule
                    Research area &                                                                                                                                                                                                                                                Top words &                                                                                                                                                                                                                        Most correlated PACS categories \\
\midrule
\endfirsthead
\caption[]{Research areas, their top-words, and their correlation with a standard classification (PACS).} \\
\toprule
                    Research area &                                                                                                                                                                                                                                                Top words &                                                                                                                                                                                                                        Most correlated PACS categories \\
\midrule
\endhead
\midrule
\multicolumn{3}{r}{{Continued on next page}} \\
\midrule
\endfoot

\bottomrule
\endlastfoot
                          AdS/CFT &              boundary, holographic, flow, bulk, critical, conformal, critical\_point, boundary\_theory, cfts, point, bootstrap, central, conformal\_anomaly, strip, fixed, free, entanglement\_entropy, conformal\_field\_theory, criticality, condition &                                               \shortstack[l]{Gauge/string duality (0.27)\\ Conformal field theory, algebraic [...] (0.23)\\ Theory of quantized fields (0.15)\\ Theories and models of [...] (0.14)\\ Critical point phenomena (0.14)}\\ \hline
                      Black holes &                                            hole, black\_hole, gravity, black, horizon, geometry, gravitational, spacetimes, spacetime, curvature, thermodynamics, einstein, schwarzschild, metric, ad, hair, relativity, space\_time, observer, graviton &                                                    \shortstack[l]{Quantum aspects of black holes, [...] (0.51)\\ Classical black holes (0.41)\\ Physics of black holes (0.32)\\ Exact solutions (0.24)\\ Higher-dimensional black holes, [...] (0.23)}\\ \hline
                 Classical fields &                                                    scalar, general, first, scalar\_field, massless, real, explicit, dynamical, second, exact, special, linear, full, symmetric, static, electromagnetic, classical, nonlinear, approximate, non\_trivial &                                  \shortstack[l]{Modified theories of gravity (0.19)\\ Lorentz and Poincaré invariance (0.16)\\ Nonlinear or nonlocal theories and [...] (0.11)\\ Exact solutions (0.10)\\ Higher-dimensional gravity and [...] (0.10)}\\ \hline
                 Collider physics &                      distribution, collision, production, cross\_sections, section, parton, hadron, cross, cross\_section, process, hadronic\_collision, scattering, correction, fragmentation, partons, kinematics, transverse, impact, event, partonic &                 \shortstack[l]{Perturbative calculations (0.29)\\ Polarization in interactions and [...] (0.28)\\ Inclusive production with [...] (0.27)\\ Total and inclusive cross sections [...] (0.26)\\ Relativistic heavy-ion collisions (0.25)}\\ \hline
                        Cosmology &                           constant, cosmological, inflation, cosmic, perturbation, vacuum, universe, inflationary, cosmology, fluctuation, inhomogeneity, tension, lambda, planck, inflaton, cosmological\_perturbation, era, epoch, density, background &                                                                 \shortstack[l]{Particle-theory and field-theory [...] (0.59)\\ Cosmology (0.32)\\ Observational cosmology (including [...] (0.28)\\ Dark energy (0.25)\\ Background radiations (0.21)}\\ \hline
                      Dark matter &                                                matter, dark, dark\_matter, detection, dm, signal, abundance, observation, relic, direct, constraint, candidate, wimp, asymmetric, prospect, dark\_matter\_particle, center, detectable, cold, contribute &                                                                                                     \shortstack[l]{Dark matter (0.74)\\ γ-ray (0.22)\\ Cosmic rays (0.19)\\ γ-ray sources; γ-ray bursts (0.17)\\ Elementary particle processes (0.17)}\\ \hline
                         Dynamics &                                                                        solution, equation, phase, space, time, system, transition, region, condition, constraint, dynamic, class, background, configuration, wave, range, motion, set, star, instability &                                       \shortstack[l]{Exact solutions (0.14)\\ Nonlinear or nonlocal theories and [...] (0.11)\\ Extended classical solutions; [...] (0.10)\\ Relativistic wave equations (0.10)\\ Modified theories of gravity (0.09)}\\ \hline
               Electroweak sector &                                                 standard, higgs, boson, particle, standard\_model, physic, lhc, sm, top, tev, collider, mssm, electroweak, minimal, phenomenology, extension, extra, supersymmetric\_model, superpartners, new\_particle &                             \shortstack[l]{Extensions of electroweak Higgs sector (0.34)\\ Supersymmetric models (0.33)\\ Non-standard-model Higgs bosons (0.30)\\ Supersymmetric partners of known [...] (0.28)\\ Standard-model Higgs bosons (0.27)}\\ \hline
Gauge theory \& Grand Unification &                                                                              dimension, coupling, scale, structure, operator, fermion, value, matrix, number, su, charge, sector, spin, group, topological, anomalous, breaking, anomaly, global, flavor & \shortstack[l]{Unified theories and models of [...] (0.22)\\ Unification of couplings; mass relations (0.17)\\ Quark and lepton masses and mixing (0.13)\\ Unified field theories and models (0.12)\\ Field theories in dimensions other [...] (0.12)}\\ \hline
                          Hadrons &                                                      decay, data, channel, bound, resonance, gamma, meson, width, experimental\_data, collaboration, kaon, prediction, experimental, measurement, admixture, narrow, process, hadronic\_decay, s0, ratio &                                                        \shortstack[l]{Decays of bottom mesons (0.30)\\ Decays of J/ψ, Υ, and other quarkonia (0.24)\\ Meson-meson interactions (0.21)\\ Decays of bottom mesons (0.20)\\ Bottom mesons (|B|>0) (0.19)}\\ \hline
     Neutrinos \& flavour physics &                                neutrino, violation, oscillation, flavor, cp, angle, mixing, experiment, lepton, flavour, hierarchy, majorana, cp\_violation, beta, leptogenesis, asymmetry, neutrino\_mass, neutrino\_oscillation, smallness, generation &                                                    \shortstack[l]{Neutrino mass and mixing (0.74)\\ Non-standard-model neutrinos, [...] (0.41)\\ Ordinary neutrinos (0.30)\\ Neutrino interactions (0.28)\\ Quark and lepton masses and mixing (0.23)}\\ \hline
             Perturbative methods &                                  amplitude, qcd, loop, diagram, sum, contribution, perturbative, expansion, vertex, rule, light\_cone, perturbative\_qcd, propagator, approach, correlator, one\_loop, evaluation, nonperturbative, kernel, diagrammatic &                                             \shortstack[l]{General properties of perturbation [...] (0.25)\\ Other nonperturbative calculations (0.24)\\ Sum rules (0.22)\\ Perturbative calculations (0.21)\\ General properties of QCD [...] (0.16)}\\ \hline
                              QCD &                                               quark, chiral, magnetic, baryon, relativistic, moment, qcd, light\_quark, strong, heavy, heavy\_quark, lattice, magnetic\_field, electric, deconfinement, chromodynamics, current, diquarks, plasma, color &                                                                            \shortstack[l]{Lattice QCD calculations (0.27)\\ Chiral symmetries (0.26)\\ Chiral Lagrangians (0.25)\\ Quark-gluon plasma (0.23)\\ General properties of QCD [...] (0.20)}\\ \hline
             Quantum Field Theory & quantum, group, quantum\_field, representation, quantisation, mechanic, quantum\_field\_theory, transformation, hamiltonians, algebra, finite\_dimensional, quantization, commutator, algebraic, arbitrary, operator, qft, invariant, analog, associated &                                                                                      \shortstack[l]{Algebraic methods (0.26)\\ Noncommutative field theory (0.25)\\ Quantum mechanics (0.22)\\ Noncommutative geometry (0.19)\\ Quantum groups (0.18)}\\ \hline
    String theory \& supergravity &                                   string, supersymmetric, superstring, six\_dimensional, modulus, super, instantons, supergravity, dyons, n2, mathcaln, superpotentials, heterotic, sigma\_models, n1, n4, gauged, space, deformation, compactifications &                                                                                                     \shortstack[l]{Supersymmetry (0.31)\\ Strings and branes (0.29)\\ Supergravity (0.29)\\ Compactification and four- [...] (0.25)\\ D branes (0.20)}\\ \hline
                   Thermodynamics &               potential, effective, interaction, limit, temperature, action, finite, local, freedom, approximation, level, weak, chemical, force, effective\_field\_theory, lagrangian, finite\_temperature, effective\_field, degree, effective\_theory &                                                                         \shortstack[l]{Finite-temperature field theory (0.26)\\ Chiral symmetries (0.09)\\ Nuclear forces (0.08)\\ Quark-gluon plasma (0.08)\\ General properties of QCD [...] (0.08)}\\ \hline
                  Uninterpretable &                                                 approach, method, analysis, recent, calculation, numerical, formalism, study, prediction, sigma, previous, work, theoretical, systematic, comparison, uncertainty, agreement, good, investigation, paper &                                                \shortstack[l]{Lattice QCD calculations (0.07)\\ Baryon resonances (S=C=B=0) (0.05)\\ Other nonperturbative calculations (0.05)\\ Few-body systems (0.05)\\ Lagrangian and Hamiltonian approach (0.05)}\\ \hline
                  Uninterpretable &                                                                 form, correction, momentum, tensor, mode, relation, higher, factor, vector, invariant, formula, angular, part, theorem, spectrum, power, dimensional, invariance, expression, derivative &                                                                 \shortstack[l]{Electromagnetic form factors (0.17)\\ Protons and neutrons (0.10)\\ Lorentz and Poincaré invariance (0.08)\\ Gauge field theories (0.06)\\ Dispersion relations (0.06)}\\ \hline
                  Uninterpretable &                                                     spectrum, low, problem, low\_energy, important, high, property, high\_energy, small, physical, soft, fundamental, behavior, analytic, behaviour, spectral, dispersion, essential, phenomenon, regime &                                                            \shortstack[l]{General properties of QCD [...] (0.07)\\ Regge formalism (0.07)\\ Wave propagation, transmission and [...] (0.05)\\ Elastic scattering (0.05)\\ Lattice gauge theory (0.05)}\\ \hline
                  Uninterpretable &                                                          different, possible, particular, present, various, mechanism, type, example, massive, several, scenario, simple, single, similar, consistent, addition, hand, different\_type, interesting, way &                                                          \shortstack[l]{Particle-theory and field-theory [...] (0.07)\\ Modified theories of gravity (0.07)\\ Field theories in dimensions other [...] (0.05)\\ Cosmology (0.05)\\ Dark energy (0.05)}\\ \hline
\end{longtable}
