At high baryon chemical potential μ_{B}, the equation of state of QCD allows a weak-coupling expansion in the QCD coupling α_{s}. The result is currently known up to and including the full next-to-next-to-leading order α_{s}^{2}. Starting at this order, the computations are complicated by the modification of particle propagation in a dense medium, which necessitates nonperturbative treatment of the scale α_{s}^{1/2}μ_{B}. We apply a hard-thermal-loop scheme for capturing the contributions of this scale to the weak-coupling expansion, and we use it to determine the leading-logarithm contribution to next-to-next-to-next-to-leading order: α_{s}^{3}ln^{2}α_{s}. This result is the first improvement to the equation of state of massless cold quark matter in 40 years. The new term is negligibly small and thus significantly increases our confidence in the applicability of the weak-coupling expansion.
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http://dx.doi.org/10.1103/PhysRevLett.121.202701 | DOI Listing |
Sci Rep
January 2025
Department of Mathematics, Khalifa University of Science and Technology, PO Box 127788, Abu Dhabi, UAE.
We propose a general approach to quasi-deform the Korteweg-De Vries (KdV) equation by deforming its Hamiltonian. The standard abelianization process based on the inherent sl(2) loop algebra leads to an infinite number of anomalous conservation laws, that yield conserved charges for definite space-time parity of the solution. Judicious choice of the deformed Hamiltonian yields an integrable system with scaled parameters as well as a hierarchy of deformed systems, some of which possibly are quasi-integrable.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Center for Gravitational Physics and Quantum Information, Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan.
We calculate the two-loop heavy quarkonium Hamiltonian within potential-nonrelativistic-QCD effective field theory in the nonannihilation channel. This calculation represents the first nontrivial step toward determining the N^{4}LO Hamiltonian in the weak coupling regime. The large amount of computation is systematically handled by employing the β expansion, differential equations for master integrals, and adopting a single-step matching procedure, in contrast to the conventional two-step approach.
View Article and Find Full Text PDFPhys Rev Lett
July 2024
Institut de Physique Théorique, Université Paris Saclay, CNRS, 91191 Gif-sur-Yvette, France.
Various observables in different four-dimensional superconformal Yang-Mills theories can be computed exactly as Fredholm determinants of truncated Bessel operators. We exploit this relation to determine their dependence on the 't Hooft coupling constant. Unlike the weak coupling expansion, which has a finite radius of convergence, the strong coupling expansion is factorially divergent, necessitating the inclusion of nonperturbative, exponentially small corrections.
View Article and Find Full Text PDFPhys Rev Lett
June 2024
Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France.
J Phys Chem A
May 2024
Department of Chemistry & Pharmaceutical Sciences and Amsterdam Institute of Molecular and Life Sciences (AIMMS), Faculty of Science, Vrije Universiteit, De Boelelaan 1083, Amsterdam 1081 HV, The Netherlands.
We study the adiabatic connection that has as weak-coupling expansion the Møller-Plesset perturbation series, generalizing to the open-shell case previous closed-shell results for the large-coupling limit. We first focus on the hydrogen atom with fractional spins, providing results along the adiabatic connection from small to large coupling strengths. We reveal an intriguing phase diagram and an equation for the large-coupling leading order that has closed-form solutions for specific choices of its relevant quantum numbers.
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