Project description
Precision calculations of quark matter in neutron star conditions
At normal temperatures, the strong force binds quarks and gluons tightly into protons and neutrons, a phenomenon called confinement. Whether deconfined quark matter (quarks in isolation) exists under extreme temperature and density conditions such as those in the early universe or in neutron stars, remains an essential open question. Answering it requires perturbative thermal quantum chromodynamics, a theoretical framework applying approximations (perturbations), but necessary calculations are lacking. The ERC-funded ExPertQCD project aims to apply ‘loop tree duality’ to perform previously impossible four-loop calculations of the quark matter equation of state. These precision calculations could significantly advance descriptions of the early universe and yield insight into new physics beyond the Standard Model.
Objective
Predicting the thermodynamic and transport properties of strongly interacting matter at the highest densities in the present-day Universe is a pressing challenge bridging modern particle and astrophysics. Determining whether deconfined Quark Matter (QM), the high-density counterpart of the Quark-Gluon Plasma created in heavy-ion collisions, exists or forms in Neutron Stars (NSs) and their mergers would be a landmark result. However, this task is severely complicated by the Sign Problem of lattice QCD, preventing the direct use of nonperturbative methods.
The ExPertQCD project will significantly advance our quantitative understanding of deconfined QM in NS conditions by employing cutting-edge perturbative thermal field theory methods. A critical challenge is the need for high-precision perturbative QCD calculations of the four-loop Equation of State (EOS) for both cold and warm QM, along with an accurate determination of the QM bulk viscosity. These milestone results will greatly improve the precision with which we understand the properties of NS matter and provide first-principles input for modern NS merger simulations.
To achieve these goals, the project will overcome limitations of traditional perturbative techniques. The key innovation lies in applying Loop Tree Duality (LTD), a powerful algorithmic method from collider physics, to address computations with nonzero chemical potentials and temperatures. This method enables the treatment of all thermal Feynman diagrams up to the four-loop order, previously considered impossible to evaluate.
By pushing the limits of perturbative thermal field theory with LTD, the project has the potential to significantly advance the description of early-Universe thermodynamics and thermal particle production rates. These advances could yield the most accurate predictions of strong phase transitions, critical for gravitational wave analysis in future experiments like LISA, and improved calculations of beyond Standard Model rates.
Fields of science (EuroSciVoc)
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques. See: The European Science Vocabulary.
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques. See: The European Science Vocabulary.
- natural sciences physical sciences theoretical physics particle physics particle accelerator
- natural sciences physical sciences astronomy observational astronomy gravitational waves
- natural sciences physical sciences astronomy stellar astronomy neutron stars
- natural sciences physical sciences astronomy astrophysics
- natural sciences physical sciences theoretical physics particle physics quarks
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Project’s keywords as indicated by the project coordinator. Not to be confused with the EuroSciVoc taxonomy (Fields of science)
Project’s keywords as indicated by the project coordinator. Not to be confused with the EuroSciVoc taxonomy (Fields of science)
Programme(s)
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Multi-annual funding programmes that define the EU’s priorities for research and innovation.
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HORIZON.1.1 - European Research Council (ERC)
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Topic(s)
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Calls for proposals are divided into topics. A topic defines a specific subject or area for which applicants can submit proposals. The description of a topic comprises its specific scope and the expected impact of the funded project.
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Funding scheme (or “Type of Action”) inside a programme with common features. It specifies: the scope of what is funded; the reimbursement rate; specific evaluation criteria to qualify for funding; and the use of simplified forms of costs like lump sums.
HORIZON-ERC - HORIZON ERC Grants
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Call for proposal
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Procedure for inviting applicants to submit project proposals, with the aim of receiving EU funding.
(opens in new window) ERC-2025-COG
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Net EU financial contribution. The sum of money that the participant receives, deducted by the EU contribution to its linked third party. It considers the distribution of the EU financial contribution between direct beneficiaries of the project and other types of participants, like third-party participants.
20014 Turku
Finland
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