Article
Physics, Multidisciplinary
Javier Mazzitelli, Pier Francesco Monni, Paolo Nason, Emanuele Re, Marius Wiesemann, Giulia Zanderighi
Summary: Studying the production of top-quark pairs in hadronic collisions is crucial for understanding the properties of the heaviest quark observed in nature, with Monte Carlo simulations being heavily relied upon and challenged by experimental measurements. This work presents the first matched computation of top-quark pair production at next-to-next-to-leading order in QCD with all-order radiative corrections using parton-shower simulations, marking an important step towards simulating other hadronic processes with color charges in the final state.
PHYSICAL REVIEW LETTERS
(2021)
Article
Astronomy & Astrophysics
Eric Braaten, Li-Ping He, Jun Jiang
Summary: XEFT is a low-energy effective field theory for charm mesons and pions that systematically improves the description of the X(3872) resonance. A new formulation and renormalization scheme have been introduced to simplify calculations in XEFT, which involve a new dynamical field for a pair of charm mesons and a subtraction of amplitudes at the complex D*(0)-(D) over bar (0) threshold. These are illustrated by calculating the complex pole energy of X and the D*(0)-(D) over bar (0) scattering amplitude to next-to-leading order using Galilean-invariant XEFT.
Article
Astronomy & Astrophysics
Christoph Mueller
Summary: The leading corrections to the differential cross section for top-pair production via gluon fusion due to third-generation dimension-six operators were computed at leading order in QCD. A systematic approach was used to treat single insertions of operators containing gluon field strength tensors, as well as explicitly loop suppressed contributions. All leading order dimension-six contributions were consequently suppressed with a loop factor 1/16 pi(2).
Article
Optics
Julia Qin, Jared Vanasse
Summary: The study of cold helium atoms has allowed for the exploration of the unique three-body Efimov bound state without the need for an external magnetic field. Utilizing the short-range effective field theory (SREFT), researchers have successfully investigated the properties of cold-atom systems, revealing the average bond lengths of the ground state and excited Efimov bound state of cold helium atoms.
Article
Physics, Multidisciplinary
Stefano Catani, Simone Devoto, Massimiliano Grazzini, Stefan Kallweit, Javier Mazzitelli, Chiara Savoini
Summary: The associated production of a Higgs boson with a top-antitop quark pair is a crucial process at the LHC, which allows for the measurement of the top-quark Yukawa coupling. The computation of radiative corrections to this process at NNLO in QCD perturbation theory is presented. This is the first computation for a 2 -> 3 process with massive colored particles at this perturbative order. A soft Higgs boson approximation for loop amplitudes is developed to quantify the impact of the unknown two-loop contribution. The NNLO corrections at a center-of-mass energy of 13 TeV increase the NLO result for the total cross section by about 4% and reduce perturbative uncertainties significantly.
PHYSICAL REVIEW LETTERS
(2023)
Article
Astronomy & Astrophysics
Loic Fernandez, Jean-Loic Kneur
Summary: The investigation of renormalization group optimized perturbation theory (RGOPT) at NNLO for thermal scalar field theory demonstrates efficient resummation and excellent convergence properties, significantly improving the renormalization scale dependence of thermodynamical quantities compared to standard perturbative expansions and other resummation methods. These results provide a useful first NNLO illustration for potential applications of this approach to more complex thermal QCD.
Article
Physics, Particles & Fields
Rui-Qing Meng, Sheng-Quan Wang, Ting Sun, Chao-Qin Luo, Jian-Ming Shen, Xing-Gang Wu
Summary: This study applies the Principle of Maximum Conformality (PMC) to analyze the top-quark decay at NNLO in QCD, eliminating renormalization scheme and scale ambiguities. The PMC scale Q(star) is determined to be 15.5 GeV, an order of magnitude smaller than the conventional choice mu(r) = m(t), indicating the small virtuality of the QCD dynamics in top-quark decay. Removal of non-conformal beta terms in the pQCD series avoids renormalon divergence, resulting in a significant increase in NLO QCD correction and suppression of NNLO QCD correction compared to conventional results obtained at mu(r) = m(t). Including NLO electroweak corrections, finite W boson width, and finite bottom quark mass, the top-quark total decay width Gamma(tot)(t) is obtained as 1.3112(-0.0189)(+0.0190) GeV.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Andreas Ekstedt, Oliver Gould, Johan Lofgren
Summary: We develop new perturbative tools to accurately study radiatively induced first-order phase transitions. By employing a consistent power counting scheme, we resolve previous issues and show that the infamous Linde problem is not as significant in these calculations as previously thought.
Article
Physics, Multidisciplinary
Roman N. Lee, Matthew D. Schwartz, Xiaoyuan Zhang
Summary: An analytic formula is provided for the total scattering cross section of an electron and a photon at order alpha(3) in QED, including both real-emission and virtual Compton scattering contributions. When combined with the recent analytic result for the pair-production cross section, the complete alpha(3) cross section is determined. Modern multiloop calculation techniques are used to compute the next-to-leading order calculation and pair-production cross section.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Michal Czakon, Alexander Mitov, Rene Poncelet
Summary: This study utilizes multijet rates to explore quantum chromodynamics (QCD), calculating NNLO QCD corrections for three-jet observables and three-to-two jet ratios. It demonstrates a significant reduction in the dependence of these observables on factorization and renormalization scales. This proof-of-principle computation represents a milestone in perturbative QCD.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Particles & Fields
Filip Bergabo, Jamal Jalilian-Marian
Summary: We calculate one-loop corrections to single inclusive hadron production in DIS at small x in the forward rapidity region using the Color Glass Condensate formalism. We show that the divergent parts of the NLO corrections cancel or lead to x evolution of the LO dipole cross section. The remaining finite parts constitute the NLO (alpha(s)) corrections to the LO single inclusive hadron production cross section in DIS at small x.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Guoxing Wang, Xiaofeng Xu, Yongqi Xu, Li Lin Yang
Summary: For the first time, a calculation of the complete next-to-leading order corrections to the gg -> ZH process is presented. The method of small mass expansion is used to tackle the challenging two-loop virtual amplitude, taking into account the top quark mass dependence. Reliable numeric results are obtained in all kinematic regions, and phenomenological predictions are provided for the total and differential cross sections at the Large Hadron Collider and its future upgrades. These results are crucial for reducing the theoretical uncertainties and providing theoretical inputs for future precision experimental collider programs.
Article
Physics, Multidisciplinary
Xiang Gao, Andrew D. Hanlon, Swagato Mukherjee, Peter Petreczky, Philipp Scior, Sergey Syritsyn, Yong Zhao
Summary: This study reports the first lattice QCD calculation of pion valence quark distribution with next-to-next-to-leading order perturbative matching correction. Through renormalization and perturbative matching, reliable determination of valence quark distribution within a certain range is achieved.
PHYSICAL REVIEW LETTERS
(2022)
Article
Astronomy & Astrophysics
Heribertus Bayu Hartanto, Rene Poncelet, Andrei Popescu, Simone Zoia
Summary: We compute the theoretical predictions for the production of a W boson in association with a bottom-quark pair at hadron colliders at NNLO in QCD. We derive an analytic expression for the required two-loop five-particle amplitudes in the leading color approximation employing finite-field methods. Numerical results show an improvement in the perturbative convergence upon inclusion of NNLO QCD corrections.
Article
Physics, Multidisciplinary
V. M. Braun, Yao Ji, Jakob Schoenleber
Summary: Deeply virtual Compton scattering provides information on the transverse position and longitudinal momentum of quarks and gluons in the proton through the generalized parton distributions. We have calculated the two-loop, next-to-next-to-leading order (NNLO) coefficient functions of deeply virtual Compton scattering associated with the dominant Compton form factors H and epsilon at high energies, in anticipation of high-precision experimental data from the Electron-Ion Collider. The NNLO correction to the imaginary part of H is found to be rather large for simple generalized parton distribution models, up to a factor of 2 at the input scale Q(2) = 4 GeV2, due to a cancellation between quark and gluon contributions.
PHYSICAL REVIEW LETTERS
(2022)
