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[Display omitted] Several Pulsar Timing Array (PTA) Collaborations have recently provided strong evidence for a nHz Stochastic Gravitational-Wave Background (SGWB). Here we investigate the implications of a first-order phase transition occurring within the early Universe's dark quantum chromodynamics epoch, specifically within the framework of the mirror twin Higgs dark sector model. Our analysis indicates a distinguishable SGWB signal originating from this phase transition, which can explain the measurements obtained by PTAs. Remarkably, a significant portion of the parameter space for the SGWB signal also effectively resolves the existing tensions in both the H 0 and S 8 measurements in Cosmology. This intriguing correlation suggests a possible common origin of these three phenomena for 0.2 < Δ N eff < 0.5 , where the mirror dark matter component constitutes less than 30 % of the total dark matter abundance. Next-generation CMB experiments such as CMB-S4 can test this parameter region. [ABSTRACT FROM AUTHOR]

[Display omitted] Jet quenching has long been regarded as one of the key signatures for the formation of quark-gluon plasma in heavy-ion collisions. Despite significant efforts, the separate identification of quark and gluon jet quenching has remained as a challenge. Here we show that J / ψ in high transverse momentum ( p T ) region provides a uniquely sensitive probe of in-medium gluon energy loss since its production at high p T is particularly dominated by gluon fragmentation. Such gluon-dominance is first demonstrated for the baseline of proton-proton collisions within the framework of leading power non-relativistic quantum chromodynamics factorization formalism. We then use the linear Boltzmann transport model combined with hydrodynamics for the simulation of jet-medium interaction in nucleus-nucleus collisions. The satisfactory description of experimental data on both nuclear modification factor R AA and elliptic flow v 2 reveals, for the first time, that the gluon jet quenching is the driving force for high p T J / ψ suppression. This novel finding is further confirmed by the data-driven Bayesian analyses of relevant experimental measurements, from which we also obtain the first quantitative extraction of the gluon energy loss distribution in the quark-gluon plasma. [ABSTRACT FROM AUTHOR]

[Display omitted] We perform a lattice QCD calculation of the η c → 2 γ decay width using a model-independent method that requires no momentum extrapolation of the off-shell form factors. This method also provides a straightforward and simple way to examine the finite-volume effects. The calculation is accomplished using N f = 2 twisted mass fermion ensembles. The statistically significant excited-state effects are observed and eliminated using a multi-state fit. The impact of fine-tuning the charm quark mass is also examined and confirmed to be well-controlled. Finally, using three lattice spacings for the continuum extrapolation, we obtain the decay width Γ η c γ γ = 6.67 (16) stat (6) syst keV, which differs significantly from the Particle Data Group's reported value of Γ η c γ γ = 5.4 (4) keV (2.9 σ tension). We provide insight into the comparison between our findings, previous theoretical predictions, and experimental measurements. [ABSTRACT FROM AUTHOR]

I describe the history of the calculations of NLO and NNLO QCD corrections to weak decays of mesons, particle–antiparticle mixing and electric dipole moments (EDMs) in the period 1988–2023. Also existing calculations of electroweak and QED corrections to these processes are included in this presentation. These efforts bear some analogies to the climbing of Himalayas and various expeditions by several teams of strongly motivated "climbers" allowed to move this field from the LO through the NLO to the NNLO level. We also summarize the most recent calculations within the Standard Model Effective Field Theory. The material is meant to be an up to date review of this very advanced field in non-technical terms as much as possible and a guide to the rich literature on NLO and NNLO corrections in question. In particular we stress for which processes these calculations are crucial for the tests of the Standard Model and to be able to differentiate between numerous New Physics models. It includes also several anecdotes related to the climbs that I was involved in. I hope that some of the comments made in the course of the presentation could turn out to be not only amusing but also instructive. [ABSTRACT FROM AUTHOR]

We investigate the neutron star (NS) equation of state (EOS) by incorporating multi-messenger data of GW170817, PSR J0030 + 0451, PSR J0740 + 6620, and state-of-the-art theoretical progresses, including the information from chiral effective field theory (χ EFT) and perturbative quantum chromodynamics (pQCD) calculation. Taking advantage of the various structures sampling by a single-layer feed-forward neural network model embedded in the Bayesian nonparametric inference, the structure of NS matter's sound speed c s is explored in a model-agnostic way. It is found that a peak structure is common in the c s 2 posterior, locating at (2.4 - 4.8) ρ sat (nuclear saturation density) and c s 2 exceeds c 2 / 3 at 90% credibility. The non-monotonic behavior suggests evidence of the state deviating from the hadronic matter inside the very massive NSs. Assuming the new/exotic state is featured as it is softer than typical hadronic models or even with hyperons, we find that a sizable (⩾ 10 - 3 M ⊙ ) exotic core, likely made of quark matter, is plausible for the NS with a gravitational mass above about 0.98 M TOV , where M TOV represents the maximum gravitational mass of a non-rotating cold NS. The inferred M TOV = (2.18 - 0.13 + 0.27) M ⊙ (90% credibility) is well consistent with the value of (2.17 - 0.12 + 0.15) M ⊙ estimated independently with GW170817/GRB 170817A/AT2017gfo assuming a temporary supramassive NS remnant formed after the merger. PSR J0740 + 6620, the most massive NS detected so far, may host a sizable exotic core with a probability of ≈ 0.36. [ABSTRACT FROM AUTHOR]

In this review, we present the current state of the art of our understanding of the spectrum of excited strongly interacting particles and discuss methods that allow for a systematic and model-independent calculation of the hadron spectrum. These are lattice QCD and effective field theories. Synergies between both approaches can be exploited allowing for a deeper understanding of the hadron spectrum. Results based on effective field theories and hadron–hadron scattering in lattice QCD or combinations thereof are presented and discussed. We also show that the often used Breit–Wigner parametrization is at odds with chiral symmetry and should not be used in case of strongly coupled channels. [ABSTRACT FROM AUTHOR]

Infrared divergences in the perturbative expansion of gauge theory amplitudes and cross sections have been a focus of theoretical investigations for almost a century. New insights still continue to emerge, as higher perturbative orders are explored, and high-precision phenomenological applications demand an ever more refined understanding. This review aims to provide a pedagogical overview of the subject. We briefly cover some of the early historical results, we provide some simple examples of low-order applications in the context of perturbative QCD, and discuss the necessary tools to extend these results to all perturbative orders. Finally, we describe recent developments concerning the calculation of soft anomalous dimensions in multi-particle scattering amplitudes at high orders, and we provide a brief introduction to the very active field of infrared subtraction for the calculation of differential distributions at colliders. [ABSTRACT FROM AUTHOR]

We present a nonperturbative study of the form factor associated with the projection of the full four-gluon vertex on its classical tensor, for a set of kinematics with one vanishing and three arbitrary external momenta. The treatment is based on the Schwinger-Dyson equation governing this vertex, and a large-volume lattice simulation, involving ten thousand gauge field configurations. The key hypothesis employed in both approaches is the "planar degeneracy", which classifies diverse configurations by means of a single variable, thus enabling their meaningful "averaging". The results of both approaches show notable agreement, revealing a considerable suppression of the averaged form factor in the infrared. The deviations from the exact planar degeneracy are discussed in detail, and a supplementary variable is used to achieve a more accurate description. The effective charge defined through this special form factor is computed within both approaches, and the results obtained are in excellent agreement. [ABSTRACT FROM AUTHOR]

The Batalin-Vilkovisky function is a central component in the modern formulation of the background field method and the physical applications derived from it. In the present work we report on novel lattice results for this particular quantity, obtained by capitalizing on its equality with the Kugo-Ojima function in the Landau gauge. The results of the lattice simulation are in very good agreement with the predictions derived from a continuum analysis based on the corresponding Schwinger-Dyson equations. In addition, we show that an important relation connecting this function with the ghost propagator is fulfilled rather accurately. With the aid of these results, we carry out the first completely lattice-based determination of the process-independent strong running interaction, employed in a variety of phenomenological studies. [ABSTRACT FROM AUTHOR]

We consider the production of a Standard-Model (SM) Higgs boson in gluon fusion in hadronic collisions and compute the QCD corrections up to next-to-next-to-leading order (NNLO) and match them to parton showers (NNLO+PS). The complete dependence on the top-quark mass is taken into account without making any approximations to the top quark loops mediating the coupling between the gluons and the Higgs boson. To this end, we have included the g g → H amplitudes up to three loops and the p p → H +jet amplitudes up to two loops in the full SM theory. This is the first fully differential calculation of the top-quark mass effects up to NNLO in QCD, and we study their impact on relevant observables for the LHC. [ABSTRACT FROM AUTHOR]

We study the time-momentum representation of the kernel needed to compute the hadronic vacuum polarization contribution to the muon g -2 in the space-like region at next-to-leading order. For small values of the time, we present analytical series expansions; for large values of the time, we present numerical series expansions which overcome the problems showed by naïve asymptotic expansions. These results are to be employed in lattice QCD determination of the hadronic vacuum polarization contribution to the muon g -2 at next-to-leading order. [ABSTRACT FROM AUTHOR]

We report the p + p and p + d differential cross sections measured in the SeaQuest experiment for J / ψ and ψ (2 S) production at ▪ beam energy covering the forward x -Feynman (x F) range of 0.5 < x F < 0.9. The measured cross sections are in good agreement with theoretical calculations based on the nonrelativistic QCD (NRQCD) using the long-distance matrix elements deduced from a recent global analysis of proton- and pion-induced charmonium production data. The σ ψ (2 S) / σ J / ψ cross section ratios are found to increase as x F increases, indicating that the q q ¯ annihilation process has larger contributions in the ψ (2 S) production than the J / ψ production. The σ p d / 2 σ p p cross section ratios are observed to be significantly different for the Drell-Yan process and J / ψ production, reflecting their different production mechanisms. We find that the σ p d / 2 σ p p ratios for J / ψ production at the forward x F region are sensitive to the d ¯ / u ¯ flavor asymmetry of the proton sea, analogous to the Drell-Yan process. The transverse momentum (p T) distributions for J / ψ and ψ (2 S) production are also presented and compared with data collected at higher center-of-mass energies. [ABSTRACT FROM AUTHOR]

We report a proof-of-principle lattice QCD simulation of the electric and magnetic polarizabilities for a neutral pion in the four-point function method. The results are based on the same quenched Wilson ensembles on a 24 3 × 48 lattice at β = 6.0 with pion mass from 1100 to 370 MeV previously used for a charged pion. For electric polarizability, the results are largely consistent with those from the background field method and ChPT. In contrast, there are significant differences for magnetic polarizability among the four-point function method, the background field method, and ChPT. The situation points to the important role of disconnected diagrams for a neutral pion. We elucidate a transparent quark decomposition in the four-point function method that can be used to shed light on the issue. [ABSTRACT FROM AUTHOR]

The standard formulation of parton physics involves light-cone correlations of quark and gluon fields in a hadron, which leads to a widespread impression that it can only be studied through real-time Hamiltonian dynamics or light-front quantization, which are challenged by non-perturbative computations with a pertinent regulator for light-cone/rapidity divergences (or zero modes). As such, standard lattice QCD studies have been limited to indirect parton observables such as first few moments and short-distance correlations, which do not provide the x -distributions without solving the model-dependent inverse problem. Here I describe an alternative formulation of partons in terms of equal-time (or Euclidean) correlators, which allows to compute precision-controlled x -distribution through lattice QCD simulations. This approach is in accord with Weinberg's pioneering idea of effective field theory as well as Wilson's renormalization group, in which the large hadron momentum serves as a natural cut-off for light-cone/rapidity divergences and can ultimately be eliminated through a method like the "perfect action" program in lattice QCD. [ABSTRACT FROM AUTHOR]

Approximate knowledge of the renormalon structure of the Bjorken polarised sum rule (BSR) Γ ‾ 1 p − n (Q 2) leads to the corresponding BSR characteristic function that allows us to evaluate the leading-twist part of BSR. In our previous work [1] , this evaluation (resummation) was performed using perturbative QCD (pQCD) coupling a (Q 2) ≡ α s (Q 2) / π in specific renormalisation schemes. In the present paper, we continue this work, by using instead holomorphic couplings [ a (Q 2) ↦ A (Q 2) ] that have no Landau singularities and thus require, in contrast to the pQCD case, no regularisation of the resummation formula. The D = 2 and D = 4 terms are included in the Operator Product Expansion (OPE) of inelastic BSR, and fits are performed to the available experimental data in a specific interval (Q min 2 , Q max 2) where Q max 2 = 4.74 GeV 2. We needed relatively high Q min 2 ≈ 1.7 GeV 2 in the pQCD case since the pQCD coupling a (Q 2) has Landau singularities at Q 2 ≲ 1 GeV 2. Now, when holomorphic (AQCD) couplings A (Q 2) are used, no such problems occur: for the 3 δ AQCD and 2 δ AQCD variants the preferred values are Q min 2 ≈ 0.6 GeV 2. The preferred values of α s in general cannot be unambiguously extracted, due to large uncertainties of the experimental BSR data. At a fixed value of α s MS ‾ (M Z 2) , the values of the D = 2 and D = 4 residue parameters are determined in all cases, with the corresponding uncertainties. [ABSTRACT FROM AUTHOR]

In the present work, we construct the diquark-antidiquark type four-quark currents to investigate the mass spectrum of the ground state hidden-charm-hidden-strange tetraquark states with the quantum numbers J P C = 0 + + , 1 + − , 1 + + and 2 + + via the traditional QCD sum rules in a comprehensive way. We update old calculations, perform new calculations and analysis in a rigorous way, and take account of the net light-flavor S U (3) breaking effects in a consistent way. And we make more reasonable identifications for the X (3960) , X (4140) , X (4274) , X (4500) , X (4685) and X (4700) and supersede some old identifications. Furthermore, we consider our previous theoretical predictions, and make reasonable/suitable identifications of the new LHCb states h c (4000) and χ c 1 (4010). [ABSTRACT FROM AUTHOR]

In the Standard Model of particle physics, the axial current is not conserved, due both to fermion masses and to the axial anomaly. Using perturbative quantum chromodynamics, we calculate matrix elements of the local and non-local axial current for a gluon target, clarifying their connection with the axial anomaly. In so doing, we also reconsider classic results obtained in the context of the nucleon spin sum rule as well as recent results for off-forward kinematics. An important role is played by the infrared regulator, for which we put a special emphasis on the nonzero quark mass. We highlight cancellations that take place between contributions from the axial anomaly and the quark mass, and we elaborate on the relation of those cancellations with the conservation of angular momentum. [ABSTRACT FROM AUTHOR]

In this paper, we carry out an investigation into the semileptonic decays D s + → K 0 ℓ + ν ℓ with ℓ = (e , μ) by employing the QCD light-cone sum rules approach. The vector transition form factor (TFF) f + D s + K 0 (q 2) for D s + → K 0 decay is calculated while considering its next-to-leading order contribution. Subsequently, we briefly introduce the twist-2, 3 kaon distribution amplitudes, which are calculated by using QCD sum rules within the framework of the background field theory. At the large recoil point, the TFF has f + D s + K 0 (0) = 0.692 − 0.026 + 0.027. Then, we extrapolate f + D s + K 0 (q 2) to the whole physical q 2 -region via the simplified z (q 2 , t) -series expansion, and the behavior of TFF f + D s + K 0 (q 2) is exhibited in the numerical results part, including the theoretical and experimental predictions for comparison. In addition, we compute the differential branching fraction B (D s + → K 0 ℓ + ν ℓ) with the electron and muon channels, which are expected to be B (D s + → K 0 e + ν e) = 3.379 − 0.275 + 0.301 × 10 − 3 and B (D s + → K 0 μ + ν μ) = 3.351 − 0.273 + 0.299 × 10 − 3 as well as contained other results for comparison. Our results show good agreement with the BESIII measurements and theoretical predictions. Furthermore, we present our prediction with respect to the CKM matrix element | V c d | by using the B (D s + → K 0 e + ν e) result from BESIII Collaboration, yielding | V c d | = 0.221 − 0.010 + 0.008. Finally, we provide the ratio between D s + → K 0 e + ν e and D s + → η e + ν e channels, i.e. R K 0 / η e = 0.144 − 0.020 + 0.028. [ABSTRACT FROM AUTHOR]

We study the out-of-time-order correlators (OTOC) of Skyrmion as baryon in the D0-D4/D8 model which is expected to be holographically dual to QCD with instantons as D0-branes or with a non-zero theta angle. Baryon states are identified to the excitations of the Skyrmion which are described by a holographic quantum mechanical system in this model. By employing the definition of OTOC in quantum mechanics, we derive the formulas and demonstrate explicitly the numerical calculations of the OTOC. Our calculation illustrates the quantum OTOC with imaginary Lyapunov coefficient indicates the possibly metastable baryonic status in the presence of the instanton while the classical OTOC can not, thus it reveals the instantonic or theta-dependent features of QCD are dominated basically by its quantum properties. Furthermore, the OTOC also implies the baryonic phase becomes really chaotic with real Lyapunov exponent if the instanton charge increases sufficiently which agrees with the unstable baryon spectrum presented in this model. In this sense, we believe the OTOC may be treated as a tool to detect the baryonic phase structure of QCD. [ABSTRACT FROM AUTHOR]

Parts 3 and 4 of the original Abstract have been modified as: 3. I use these new values of the D = 6 , 8 power corrections to extract α s from the BNP lowest moment. To order α s 4 , I find within the SVZ expansion: α s (M τ) | e + e − S V Z = 0.3081 (49) f i t (71) α s 5 [resp. 0.3260 (47) f i t (62) α s 5 ] implying α s (M Z) | e + e − S V Z = 0.1170 (6) (3) e v o l [resp. 0.1192 (6) (3) e v o l ] for Fixed Order (FO) [resp. Contour Improved (CI)] PT series. They lead to the mean: α s (M τ) | e + e − S V Z = 0.3179 (58) f i t (81) s y s t and α s (M Z) | e + e − S V Z = 0.1182 (12) (3) e v o l where the systematic error(syst) takes into account the discrepancy between the FO and CI results. Using the lowest BNP moment, we obtain from the vector (V) component of τ -decay data: α s (M τ) | τ , V S V Z = 0.3128 (19) f i t (77) α s 5 [resp. 0.3291 (25) f i t (65) α s 5 ] implying α s (M Z) | τ , V S V Z = 0.1176 (10) (3) e v o l [resp. 0.1196 (8) (3) e v o l ] for FO [resp. CI] PT series, giving the mean: α s (M τ) | τ , V S V Z = 0.3219 (52) (91) s y s t leading to: α s (M Z) | τ , V S V Z = 0.1187 (13) (3) e v o l. The average of the two determinations from e + e − and τ -decay data is: 〈 α s (M τ) 〉 = 0.3198 (72) which implies 〈 α s (M Z) 〉 = 0.1185 (9) (3) e v o l. 4. Some (eventual) contributions beyond the SVZ expansion (1 / Q 2 , instantons and duality violation) are discussed in Sections 10 and 11 which are expected to be relatively small. [ABSTRACT FROM AUTHOR]

Understanding how momentum anisotropies arise in small collision systems is important for a quantitative understanding of collectivity in terms of QCD dynamics in small and large collision systems. In this letter we present results for small collision systems from the newly developed parton cascade Alpaca , which faithfully encodes the AMY effective kinetic theory. Alpaca reproduces quantitatively previously known results from a calculation in the single-hit approximation for small values of the coupling. We discuss in detail how such a comparison is to be carried out. Particularly at larger coupling a generic difference between the two approaches becomes apparent, namely that in parton cascades particles interact over a finite distance while in direct integrations of the Boltzmann equation the interactions are local. This leads to quantitative differences in the extracted values for the elliptic flow coefficient. These discrepancies appear in situations where the mean free path is not large compared to the interaction time and the applicability of kinetic theory is thus questionable. [ABSTRACT FROM AUTHOR]

The relationship between QCD and the string model offers a valuable perspective for exploring the interaction potential between quarks. In this study, we investigate the restoration of chiral symmetry in connection with the Unruh effect experienced by accelerating observers. Utilizing the Schwinger model, we analyze the critical point at which the string or chromoelectric flux tube between quark-antiquarks breaks with increasing separation between quarks. In this study, the critical distance for quark-antiquark chromoelectric flux tube or string breaking is determined to be r c = 1.294 ± 0.040 fm. The acceleration and Unruh temperature corresponding to this critical point signify the transition of the system's chiral symmetry from a broken to a restored state. Our estimates for the critical acceleration (a c = 1.14 × 10 34 cm/s2) and Unruh temperature (T c = 0.038 GeV) align with previous studies. This analysis illuminates the interplay between chiral symmetry restoration, the Unruh effect, and the breaking of the string or chromoelectric flux tube within the context of quark interactions. [ABSTRACT FROM AUTHOR]

A reaction model for γ + p → J / ψ + p photoproduction, which exposes the c c ¯ content of the photon in making the transition γ → c c ¯ + P → J / ψ and couples the intermediate c c ¯ system to the proton's valence quarks via Pomeron (P) exchange, is used to deliver a description of available data, viz. both differential and total cross sections from near threshold, where data has newly been acquired, to invariant mass W ≈ 300 GeV. The study suggests that it is premature to link existing γ + p → J / ψ + p data with, for instance, in-proton gluon distributions, the quantum chromodynamics trace anomaly, or pentaquark production. Further developments in reaction theory and higher precision data are necessary before the validity of any such connections can be assessed. [ABSTRACT FROM AUTHOR]

We present the even- N moments N ≤ 20 of the fourth-order (N3LO) contribution P gq (3) (x) to the quark-to-gluon splitting function in perturbative QCD. These moments, obtained by analytically computing off-shell operator matrix elements for a general gauge group, agree with all known results, in particular with the moments N ≤ 10 derived before from structure functions in deep-inelastic scattering. Using the new moments and the available endpoint constraints, we construct approximations for P gq (3) (x) which improve upon those obtained from the lowest five even moments. The remaining uncertainties of this function are now practically irrelevant at momentum fractions x > 0.1. The resulting errors of the convolution of P gq at N3LO with a typical quark distribution are small at x ≳ 10 − 3 and exceed 1% only at x ≲ 10 − 4 for a strong coupling α s = 0.2. The present results for P gq (3) (x) should thus be sufficient for most collider-physics applications. [ABSTRACT FROM AUTHOR]

We discuss a machine learning (ML) regression model to reduce the computational cost of disconnected diagrams in lattice QCD calculations. This method creates a mapping between the results of fermionic loops computed at different quark masses and flow times. The ML mapping, trained with just a small fraction of the complete data set, makes use of translational invariance and provides consistent result with comparable uncertainties over the calculation done over the whole ensemble, resulting in a significant computational gain. [ABSTRACT FROM AUTHOR]

The mass and width of the tensor tetraquark T = b b c ‾ c ‾ with spin-parity J P = 2 + are calculated in the context of the QCD sum rule method. The tetraquark T is modeled as a diquark-antidiquark state built of components b T C γ μ b and c ‾ γ ν C c ‾ T with C being the charge conjugation matrix. The mass m = (12.795 ± 0.095) GeV of the exotic tensor meson T is found by means of the two-point sum rule approach. Its full width Γ is evaluated by considering processes T → B c − B c − , B c − B c ⁎ − , and B c ⁎ − B c ⁎ −. Partial widths of these decays are computed by means of the three-point sum rule approach which is used to determine the strong couplings at relevant tetraquark-meson-meson vertices. Predictions obtained for the width Γ T = 55.5 − 9.9 + 10.6 MeV , as well as the mass of the tetraquark T can be useful in investigations of fully heavy four-quark mesons. [ABSTRACT FROM AUTHOR]

We discuss the simultaneous dispersive analyses of π K → π K and π π → K K ̄ scattering data and the κ / K 0 ∗ (700) resonance. The unprecedented statistics of present and future hadron experiments, modern lattice QCD calculations, and the wealth of new states and decays require such precise and model-independent analyses to describe final state interactions. We review the existing and often conflicting data and explain in detail the derivation of the relevant dispersion relations, maximizing their applicability range. Next, we review and extend the caveats on some data, showing their inconsistency with dispersion relations. Our main result is the derivation and compilation of precise amplitude parameterizations constrained by several π K → π K and π π → K K ̄ dispersion relations. These constrained parameterizations are easily implementable and provide the rigor and accuracy needed for modern experimental and phenomenological hadron physics. As applications, after reviewing their status and interest, we will provide new precise threshold and subthreshold parameters and review our dispersive determination of the controversial κ / K 0 ∗ (700) resonance and other light-strange resonances. [ABSTRACT FROM AUTHOR]

We suppose that there exist three vector hidden-charm tetraquark states with the J P C = 1 − − at the energy about 4.5 GeV , and investigate the two-body strong decays systematically. We obtain thirty QCD sum rules for the hadronic coupling constants based on rigorous quark-hadron duality, then obtain the partial decay widths, therefore the total widths approximately, which are compatible with the experimental data of the Y (4500) from the BESIII collaboration. The Y (4500) may be one vector tetraquark state having three main Fock components, or consists of three different vector tetraquark states. We can search for the typical decays Y → D ¯ 1 0 D 0 − D ¯ 0 D 1 0 2 , D ¯ 1 − D + − D ¯ − D 1 + 2 , D ¯ 0 0 D ⁎ 0 − D ¯ ⁎ 0 D 0 0 2 , D ¯ 0 − D ⁎ + − D ¯ ⁎ − D 0 + 2 , η c ω , J / ψ ω to diagnose the nature of the Y (4500). [ABSTRACT FROM AUTHOR]

Gluon transverse-momentum dependent distributions (TMDs) are very important for revealing the internal structure of the proton. They correspond to a variety of experiments and are among the major tasks of the future electron-ion colliders. In this paper, we calculate the T-even gluon TMDs at the leading twist within the Basis Light-front Quantization framework. We employ the light-front wave functions of the proton obtained from a light-front quantized Hamiltonian with Quantum Chromodynamics input determined for its valence Fock-sector with three constituent quarks and an additional Fock-sector, encompassing three quarks and a dynamical gluon, with a three-dimensional confinement. After obtaining the numerical results we investigate the properties of gluon TMDs by checking whether they satisfy the Mulders-Rodrigues inequalities and investigate the correlations between transverse and longitudinal degrees of freedom. With their connection to unintegrated gluon distributions in mind, we further investigate the limiting behaviors of gluon TMDs in the small- x and large- x regions. [ABSTRACT FROM AUTHOR]

We study the confinement/deconfinement transition of QCD matter for a quark-gluon plasma at finite density using AdS/QCD duality. In order to determine the critical temperature and its dependence on the quark chemical potential, the semi-classical Hawking-Page approach is considered for a charged AdS black hole. The result obtained is consistent with the QCD phase diagram, with the critical temperature decreasing as the chemical potential increases. Using the soft wall holographic model, the value of quark density in which the phase transition occurs at zero temperature is estimated. For higher densities the QCD matter is deconfined, independent of the temperature. [ABSTRACT FROM AUTHOR]

We present the light-quark mass dependence of the Λ (1405) resonance at leading order in a renormalizable framework of covariant chiral effective field theory. The meson-baryon scattering amplitudes, which are obtained by solving the scattering equation within time-ordered perturbation theory, follow the quark mass trajectory of the Coordinated Lattice Simulations consortium. At M π ≈ 200 MeV and M K ≈ 487 MeV, our parameter-free prediction of Λ (1405) poles is consistent with the recent lattice results of BaSc Collaboration [Phys. Rev. Lett. 132, 051901 (2024)]. Varying the pion mass from 135 MeV to 400 MeV, we present the evolution of double-pole positions of Λ (1405) : the higher pole remains a resonance around the K ¯ N threshold; whereas the lower pole undergoes a transition from resonance to a virtual state, and ultimately to a bound state of the π Σ system, which could be verified by the forthcoming lattice QCD simulations. [ABSTRACT FROM AUTHOR]

We compute the baryonic screening masses of the nucleon and of its negative parity partner in thermal QCD with N f = 3 massless quarks for a wide range of temperatures, from T ∼ 1 GeV up to ∼160 GeV. The computation is performed by Monte Carlo simulations of lattice QCD with O (a) -improved Wilson fermions by exploiting a recently proposed strategy to study non-perturbatively QCD at very high temperature. Very large spatial extensions are considered in order to have negligible finite volume effects. For each temperature we have simulated 3 or 4 values of the lattice spacing, so as to perform the continuum limit extrapolation with confidence at a few permille accuracy. The degeneracy of the positive and negative parity-state screening masses, expected from Ward identities associated to non-singlet axial transformations, provides further evidence for the restoration of chiral symmetry in the high temperature regime of QCD. In the entire range of temperatures explored, the baryonic masses deviate from the free theory result, 3 π T , by 4–8%. The contribution due to the interactions is clearly visible up to the highest temperature considered, and cannot be explained by the expected leading behavior in the QCD coupling constant g over the entire range of temperatures explored. [ABSTRACT FROM AUTHOR]

This White Paper presents an overview of the current status and future perspective of QCD research, based on the community inputs and scientific conclusions from the 2022 Hot and Cold QCD Town Meeting. We present the progress made in the last decade toward a deep understanding of both the fundamental structure of the sub-atomic matter of nucleon and nucleus in cold QCD, and the hot QCD matter in heavy ion collisions. We identify key questions of QCD research and plausible paths to obtaining answers to those questions in the near future, hence defining priorities of our research over the coming decades. [ABSTRACT FROM AUTHOR]

G (2) is the smallest exceptional group and it is the simplest and viable gauge group to minimally extend the strong interaction sector: G (2) includes the group S U (3) of Quantum Chromodynamics (QCD) as a maximal subgroup and it is equipped with six additional gluons that can acquire mass via a Higgs mechanism driven by a new Higgs particle and constitute dark matter. In this article I want to describe how the exceptional G (2) group can be a physical gauge group, capable of extending the Standard Model (SM) of particles and including a versatile dark sector, which is compatible with experimental observations. In fact, due to its peculiar mathematical features, the group G (2) manifests some complex features, not properly considered in literature, which guarantee its correct use in physics, as its { 3 } ⊕ { 3 ‾ } decompositions w.r.t. S U (3) can acquire a complex structure. The resulting framework can be a solid Beyond Standard Model (BSM) solution for the dark matter (DM) problem, in the form of massive complex scalar glueballs, and it includes the proper color representations for quarks and leptons. Several quantum field theory features are discussed, like the G (2) coupling constant running and its spectrum before and after the phase transition, along with all the DM astrophysical realizations, in order to present the unexpected potential of this gauge group. [ABSTRACT FROM AUTHOR]

Recently, a hadronic state, named X (3960) , about 3.96 GeV with J P C = 0 + + was observed in LHCb experiment. From its the decay modes, it's reasonable to categorize this structure to novel hadronic state. In this paper, we examine the tetraquark interpretation for the structure of X (3960) in the configurations of [ 3 c ] c s ⊗ [ 3 ¯ c ] c ¯ s ¯ , and the QCD sum rules calculations of the mass spectrum are performing. Numerical results indicted that the observed X (3900) could be embedded into the [ 3 c ] c s ⊗ [ 3 ¯ c ] c ¯ s ¯ configuration. Various X (3960) decay modes are evaluated, which are critical for pinning down its configuration and left for experimental verification. In the same way, we evaluate as well the c ¯ q c ¯ q , b ¯ s b ¯ s , and b ¯ q b ¯ q tetraquark state with 0 + + quantum number in the configuration of [ 3 c ] c s ⊗ [ 3 ¯ c ] c ¯ s ¯ and find that there might exist six such ground states. [ABSTRACT FROM AUTHOR]

We demonstrate that at sufficiently high energies when the eikonal regime is established for hadronic interactions, the double scattering subprocess can be clearly identified and isolated in quasi-elastic deuteron electro-disintegration processes. Comparing theoretical calculations with the recent high precision experimental data we present a "proof of principle" that these processes can be used to study advanced issues related to hadron formation in QCD. In this case, the double scattering represents as a fermi-scale "detector" which probes products of high Q 2 scattering from the bound nucleon through their rescattering from the spectator nucleon in the deuteron. [ABSTRACT FROM AUTHOR]

We study the potential of X (3872) at finite temperature in the Born-Oppenheimer approximation under the assumption that it is a tetraquark. We argue that, at large number of colors, it is a good approximation to assume that the potential consists in a real part plus a constant imaginary term. The real part is then computed adapting an approach by Rothkopf and Lafferty and using as input lattice QCD determinations of the potential for hybrids. This model allows us to qualitatively estimate at which temperature range the formation of a heavy tetraquark is possible, and to propose a qualitative picture for the dissociation of the state in a medium. Our approach can be applied to other suggested internal structures for the X (3872) and to other exotic states. [ABSTRACT FROM AUTHOR]

The low-lying energy spectrum of the static-colour-source-anti-source system in a vacuum containing light and strange quarks is computed using lattice QCD for a range of different light quark masses. The resulting levels are described using a simple model Hamiltonian and the parameters in this model are extrapolated to the physical light-quark masses. In this framework, the QCD string tension is found to be σ = 445 (3) stat (6) sys MeV. [ABSTRACT FROM AUTHOR]

This work discusses the connection between isospectrality and configurational entropy in holographic bottom-up models. We analyze the effect of monoparametric isospectral transformation in holographic decay constants and configurational entropy for a set of softwall-like models at zero temperature. We conclude that the isospectral parameter λ defines a window of possible holographic models suitable for describing spectroscopy. [ABSTRACT FROM AUTHOR]

We present the first lattice calculation of the nucleon isovector helicity parton distribution function (PDF) in the framework of large-momentum effective theory (LaMET) that uses the hybrid scheme with self-renormalization. We use ensembles generated by the MILC collaboration at lattice spacings a = { 0.1207 , 0.0888 , 0.0582 } fm, with N f = 2 + 1 + 1 flavors of highly improved staggered quarks at sea pion mass of M π ≈ 315 MeV. We use clover-improved action for our valence quarks with nucleon boost momentum P z ≈ 1.75 GeV and high-statistics measurements for the LaMET matrix elements. We perform an extrapolation to the continuum limit and improve the handling of systematic errors using renormalization-group resummation (RGR) and leading-renormalon resummation (LRR). Our final nucleon helicity PDF is renormalized in the MS ‾ scheme at energy scale μ = 2.0 GeV. We compare our results with and without the two systematic improvements of RGR and LRR at each lattice spacing as well as the continuum limit, and we see that the application of RGR and LRR greatly reduces the systematic errors across the whole x range. Our continuum results with both RGR and LRR show a small positive antiquark region for the nucleon helicity PDF as well as a change of as much as a factor of two in the central values compared to results with neither RGR or LRR. By contrast, the application of RGR and LRR only changes the central values by about 5% in the quark region. We compare our lattice results with the global fits by the JAM, NNPDF and DSSV collaborations, and we observe some tension between our results. [ABSTRACT FROM AUTHOR]

Masses and current couplings of the charmonium and bottomonium hybrids c ‾ g c and b ‾ g b with spin-parities J PC = 0 + + , 0 + − , 0 − + , 0 − − and 1 + + , 1 + − , 1 − + , 1 − − are calculated using QCD two-point sum rule method. Computations are performed by taking into account gluon condensates up to dimension 12 including terms ∼ 〈 g s 3 G 3 〉 2. The parameters of the bottom-charm hybrids b ‾ g c with quantum numbers J PC = 0 + , 0 − , 1 + , and 1 − are calculated as well. In computations the dominance of the pole contribution to sum rule results is ensured. It is demonstrated that all charmonia hybrids decay strongly to two-meson final states. The bottomonium hybrids 0 − + and 1 − + as well as the bottom-charm hybrid mesons 0 − (+) and 1 − (+) may be stable against strong two-meson decay modes. Results of the present work are compared with ones obtained using the sum rule and alternative approaches. Our predictions for parameters of the heavy hybrid mesons may be useful to study their various decay channels which are important for interpretation of ongoing and future experiments. [ABSTRACT FROM AUTHOR]

We study higher-order QCD corrections for the associated production of a top-antitop quark pair and a W boson (t t ¯ W production) in proton-proton collisions. We calculate approximate NNLO (aNNLO) and approximate N3LO (aN3LO) cross sections, with second-order and third-order soft-gluon corrections added to the exact NLO QCD result, and we also include electroweak (EW) corrections through NLO. We calculate uncertainties from scale dependence, which are reduced at higher orders, and from parton distributions, and we also provide separate results for t t ¯ W + and t t ¯ W − production. We compare our results to recent measurements from the LHC, and we find that the aN3LO QCD + NLO EW predictions provide improved agreement with the data. We also calculate differential distributions in top-quark transverse momentum and rapidity and find significant enhancements from the higher-order corrections. This is the first calculation of soft-gluon corrections in single-particle-inclusive kinematics for a 2 → 3 process where all final-state particles are massive. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the behaviors of the 3-dimensional non-Hermitian double-cover Lieb model near the band-touching points. The double-cover Lieb model is composed of two copies of Lieb configurations. Our analysis demonstrates that, near the band-touching points, the double-cover Lieb model emerges macroscopic electromagnetism, which incorporates permittivity and permeability that serve as primary causes for numerous electromagnetic phenomena. By analyzing the polarized phases of flavor and spin spaces in the double-cover Lieb model, we classify different topological phases of the model corresponding to different material phases induced by permittivity and permeability. We also discuss possible experimental schemes for realizing the 3-dimensional non-Hermitian double-cover Lieb model. The double-cover Lieb models model bears similarity to low-energy quantum chromodynamics models, extension of the non-Hermitian double-cover Lieb model could enable the exploration of even richer phase phenomena. • The emergence of macroscopic electromagnetism in the non-Hermitian double-cover Lieb model. • The different topological phases of the model induced by permittivity and permeability are classified. • Extending the model could connect particle physics, condensed matter physics, and materials science. [ABSTRACT FROM AUTHOR]

1. I report an update of my previous comparison of the theoretical value of the muon anomaly a μ ≡ 1 2 (g − 2) μ with the new measurement. One finds: Δ a μ ≡ a μ e x p − a μ t h = (143 ± 42 t h ± 22 e x p) × 10 − 11 indicating about 3 σ discrepancy between the SM predictions and experiment. 2. I improve the estimate of QCD power corrections up to dimension D = 12 and provide a new estimate of the ones up to D = 20 within the Shifman-Vainshtein-Zahkarov (SVZ) expansion by combining the ratio of the SVZ Borel/Laplace sum rules (LSR) with the Braaten-Pich and the author (BNP) τ -like decay moments for the I = 1 vector current. The results summarized in Table 1 confirm a violation of the factorization of the four-quark condensates and the value of the gluon one 〈 α s G 2 〉 from some other sources. Up to D = 20 , I do not observe any factorial nor exponential growth of the size of these power corrections. 3. I use these new values of power corrections to extract α s from the BNP lowest moment. To order α s 4 , I find within the SVZ expansion: α s (M τ) = 0.3081 (50) f i t (71) α s 5 [resp. 0.3260 (47) f i t (62) α s 5 ] implying α s (M Z) = 0.1170 (6) (3) e v o l [resp. 0.1192 (6) (3) e v o l ] for Fixed Order (FO) [resp. Contour Improved (CI)] PT series. They lead to the mean: α s (M τ) | S V Z = 0.3180 (58) f i t (99) s y s t and α s (M Z) | S V Z = 0.1182 (14) (3) e v o l where the systematic error(syst) takes into account the discrepancy between the FO and CI results. Using the lowest BNP moment, we also obtain from the V + A component of τ -decay data: α s (M τ) | τ , V + A = 0.3040 (76) f i t (68) s y s t giving: α s (M Z) | τ , V + A = 0.1166 (8) (3) e v o l. The average of the two determinations from e + e − and τ -decay is: 〈 α s (M τ) 〉 = 0.3111 (71) which implies 〈 α s (M Z) 〉 = 0.1174 (10) (3) e v o l. 4. Some (eventual) contributions beyond the SVZ expansion (1 / Q 2 , instantons and duality violation) are discussed in Sections 10 and 11. [ABSTRACT FROM AUTHOR]

In [1] , we showed that the gravitational wave spectrum from trans-Planckian shockwave scattering in Einstein gravity is determined by the gravitational Lipatov vertex expressed as the bilinear double copy Γ μ ν = 1 2 C μ C ν − 1 2 N μ N ν where C μ is the QCD Lipatov vertex and N μ is the QED soft photon factor. We show here that this result can be directly obtained by careful application of the classical color-kinematic duality to the spectrum obtained in gluon shockwave collisions. [ABSTRACT FROM AUTHOR]

In this paper, we present an improved analysis of the top-quark pair production via the process e + e − → γ ⁎ → t t ¯ near the threshold region up to next-to-next-to-next-to-leading order (N3LO) QCD corrections. Near the threshold region, the top-quark velocity v tends to zero, leading to Coulomb singularity. To achieve a reasonable prediction in the threshold region, we reconstruct the analytical expression for the Coulomb-terms up to N3LO accuracy by using the PSLQ algorithm, whose numerical values agree well with the previous N3LO-level calculations. It is found that the N3LO series still has sizable renormalization scale dependence, and to improve the precision of the series, we apply the Principle of Maximum Conformality to eliminate such scale dependence. After that, the Coulomb part is resummed into a Sommerfeld-Gamow-Sakharov factor, which finally leads to a much more reasonable behavior near the threshold region. [ABSTRACT FROM AUTHOR]

Ultracentral heavy ion collisions due to their exceptionally large multiplicity probe an interesting regime of quark-gluon plasma where the size is (mostly) fixed and fluctuations in the initial condition dominate. Spurred by the recent measurement of the CMS collaboration we investigate the driving factors of the increase of transverse momentum, including a complete analysis of the influence of the QCD equation of state. Particularly interesting is the influence of the centrality selection as well as the initial energy deposition. [ABSTRACT FROM AUTHOR]

Decays of the neutral and long-lived η and η ′ mesons provide a unique, flavor-conserving laboratory to test low-energy Quantum Chromodynamics and search for new physics beyond the Standard Model. They have drawn world-wide attention in recent years and have inspired broad experimental programs in different high-intensity-frontier centers. New experimental data will offer critical inputs to precisely determine the light quark mass ratios, η – η ′ mixing parameters, and hadronic contributions to the anomalous magnetic moment of the muon. At the same time, it will provide a sensitive probe to test potential new physics. This includes searches for hidden photons, light Higgs scalars, and axion-like particles that are complementary to worldwide efforts to detect new light particles below the GeV mass scale, as well as tests of discrete symmetry violation. In this review, we give an update on theoretical developments, discuss the experimental opportunities, and identify future research needed in this field. [ABSTRACT FROM AUTHOR]