Review
Physics, Multidisciplinary
Andrei Alexandru, Gokce Basar, Paulo F. Bedaque, Neill C. Warrington
Summary: This article reviews a new approach to solve the sign problem based on the complexification of field space and the accompanying mathematical theory. The underlying mathematical ideas and developed algorithms are described, along with successful examples. The article also outlines future research directions, including the growing use of machine learning techniques.
REVIEWS OF MODERN PHYSICS
(2022)
Article
Astronomy & Astrophysics
Chowdhury Aminul Islam, Munshi G. Mustafa, Rajarshi Ray, Pracheta Singha
Summary: We discuss a novel approach for estimating the partition function in effective model frameworks with multiple extrema in effective potentials, making it difficult to determine the mean field. Using this approach, we present a consistent model to investigate the thermodynamic properties of gluon quasiparticles as a function of temperature, in both the color confined and deconfined phases.
Article
Astronomy & Astrophysics
Jan M. Pawlowski, Manuel Scherzer, Christian Schmidt, Felix P. G. Ziegler, Felix Ziesche
Summary: We propose a novel simulation strategy for Yang-Mills theories with a complex coupling, based on the Lefschetz thimble decomposition. This approach can potentially be adapted to QCD at finite density and real-time simulations, offering a solution to sign problems in Monte Carlo calculations within models with complex actions. Our algorithm demonstrates exponential improvements over standard reweighting approaches, despite facing a residual sign problem.
Article
Physics, Nuclear
M. Giordano, K. Kapas, S. D. Katz, D. Nogradi, A. Pasztor
Summary: This study provides the first direct determination of the leading singularity of pressure in the complex chemical potential mu(B) plane in lattice QCD, without relying on a finite-order truncation of the Taylor expansion. By redefining the fermion determinant, the analyticity issues in the complex mu(B) plane of QCD with rooted staggered fermions are solved. The analysis shows that the radius of convergence near the crossover temperature at zero chemical potential is approximately mu(B)/T, which is independent of temperature.
Article
Physics, Nuclear
Jana N. Guenther, Szabolcs Borsanyi, Zoltan Fodor, Ruben Kara, Sandor D. Katz, Paolo Parotto, Attila Pasztor, Claudia Ratti, Kalman K. Szabo
Summary: An efficient method to study the QCD phase diagram at small finite density is to extrapolate thermodynamical observables from imaginary chemical potential. The phase diagram features a crossover line starting from the transition temperature already determined at zero chemical potential. In this work, the focus is on the Taylor expansion of this line up to mu(4) contributions, and the continuum extrapolation of the crossover temperature based on different observables at several lattice spacings is presented.
Article
Physics, Particles & Fields
Ji-Chong Yang, Xiao-Ting Chang, Jian-Xing Chen
Summary: The effect of an external electric field on quark matter is investigated using lattice QCD approach, focusing on the properties of the Roberge-Weiss phase. Novel phenomena are observed at high temperatures, including oscillations of chiral condensation, absolute value of the Polyakov loop, and charge density with coordinate. A possible phase transition is implied by the different behavior of the phase of the Polyakov loop depending on whether it encloses the origin.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Peng-Cheng Chu, Qian Cao, He Liu, Xiao-Hua Li, Min Ju, Xu-Hao Wu, Ying Zhou
Summary: In this study, the thermodynamical properties of color-flavor locked (CFL) quark matter at zero temperature, finite temperature, and strong magnetic field were investigated using a quasiparticle model. The results show that considering CFL quark phase can lead to the formation of large quark stars under certain constraints.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Multidisciplinary
Gokce Basar
Summary: By utilizing a combination of Pade' resummation and conformal maps, we are able to efficiently determine the location of the critical point, constrain nonuniversal parameters, and numerically evaluate the equation of state near the critical point in the crossover region of the Ising universality class.
PHYSICAL REVIEW LETTERS
(2021)
Review
Multidisciplinary Sciences
Owe Philipsen
Summary: The article discusses the thermal restoration of chiral symmetry in QCD and the expected transition into a phase transition with a critical endpoint as baryon density increases. By simulating at zero and imaginary baryon chemical potential, the location of a potential non-analytic phase transition and its critical endpoint can be constrained. Studies show a possible critical point bound to μ(B) & GSIM; 3T.
Article
Physics, Nuclear
Aftab Ahmad, Ali Murad
Summary: We study the dynamical chiral symmetry breaking/restoration in the NJL model for different numbers of light quark flavors and colors. We observe a strong interplay between the number of colors and flavors, where larger values of N-c enhance quark mass and condensate, while higher values of N-f suppress them. In the QCD phase diagram at finite temperature and quark chemical potential, we find that N-c is enhanced while N-f is suppressed, affecting the critical temperature and location of the critical endpoint. Our findings are consistent with predictions from lattice QCD and Schwinger-Dyson equations.
Article
Physics, Multidisciplinary
Yang-yang Tan, Yong-rui Chen, Wei-jie Fu
Summary: This paper investigates the real-time dynamics of the O(4) scalar theory using the Schwinger-Keldysh closed time path. The flow equations for effective action and correlation functions are derived, and an analytic expression for the four-point vertex is obtained. Spectral functions at different temperatures and momentums are calculated. Furthermore, the dynamical critical exponent for the phase transition near the critical temperature in the 3+1 dimensional O(4) scalar theory is calculated to be approximately 2.023.
Article
Astronomy & Astrophysics
Zhibin Li, Jingmin Liang, Song He, Li Li
Summary: Baryon number fluctuations can be used to explore the QCD phase diagram experimentally, and may provide insights into the critical endpoint (CEP). We used a holographic QCD model to compute higher-order baryon number susceptibilities and found that the model agrees well with experimental data, suggesting that it can be used to locate the CEP.
Article
Astronomy & Astrophysics
Hiroaki Kouno, Kouji Kashiwa, Takehiro Hirakida
Summary: The study focused on the nonanalyticity and sign problem of the Z(3)-symmetric heavy quark model at low temperature, analyzing the nonanalyticity in relation to the zeros of the grand canonical partition function. The Z(3)-symmetric effective Polyakov-line model (EPLM) and the effects of imaginary quark chemical potential were considered, revealing the significant impact of Z(3) symmetry on the structure of zeros in the microscopic probability density function.
Review
Multidisciplinary Sciences
Victor V. Braguta
Summary: This review discusses the modern understanding of the two-color QCD phase diagram at finite baryon density and low temperatures. At low baryon density, chiral perturbation theory (ChPT) is applicable and predicts a second-order phase transition with Bose-Einstein condensation of diquarks. At larger baryon chemical potentials, interactions between baryons become important and ChPT is not applicable. Lattice studies support most of the theoretical predictions, showing a Fermi sphere composed of quarks and condensation of diquarks on its surface at large baryon densities.
Article
Astronomy & Astrophysics
Ying-Ying Li, Xing-Lin Liu, Xin-Yi Liu, Zhen Fang
Summary: This article introduces an improved soft-wall AdS/QCD model coupled to an Einstein-dilaton system, which offers the ability to study deconfining and chiral transitions simultaneously. The correlation between these transitions is investigated, and the effects of the scaling dimension of the dual operator of the dilaton on chiral transitions are observed.
Article
Physics, Nuclear
Jana N. Guenther, Szabolcs Borsanyi, Zoltan Fodor, Ruben Kara, Sandor D. Katz, Paolo Parotto, Attila Pasztor, Claudia Ratti, Kalman K. Szabo
Summary: An efficient method to study the QCD phase diagram at small finite density is to extrapolate thermodynamical observables from imaginary chemical potential. The phase diagram features a crossover line starting from the transition temperature already determined at zero chemical potential. In this work, the focus is on the Taylor expansion of this line up to mu(4) contributions, and the continuum extrapolation of the crossover temperature based on different observables at several lattice spacings is presented.
Review
Physics, Nuclear
Jana N. Guenther
Summary: In recent years, significant progress has been made in investigating the QCD phase diagram using lattice QCD simulations, with a focus on developments in the last two years. The addition of external influences or new parameter ranges has led to an increasing number of interesting results. Discussions include progress for small, finite densities, heavy quark bound states, quark mass dependence, and the influence of magnetic fields.
EUROPEAN PHYSICAL JOURNAL A
(2021)
Article
Multidisciplinary Sciences
Sz. Borsanyi, Z. Fodor, J. N. Guenther, C. Hoelbling, S. D. Katz, L. Lellouch, T. Lippert, K. Miura, L. Parato, K. K. Szabo, F. Stokes, B. C. Toth, Cs. Torok, L. Varnhorst
Summary: The standard model of particle physics describes the majority of experiments and observations involving elementary particles, with a long-standing discrepancy concerning the anomalous magnetic moment of the muon. Ongoing experiments aim to reduce measurement errors, theoretically attributed to the leading-order hadronic vacuum polarization contribution, to distinguish between experimental measurements and predictions. The developed methods using ab initio quantum chromodynamics and quantum electrodynamics simulations favor experimentally measured values over those obtained using dispersion methods, with potential for increased precision as computer technology advances.
Article
Physics, Multidisciplinary
S. Borsanyi, Z. Fodor, J. N. Guenther, R. Kara, S. D. Katz, P. Parotto, A. Pasztor, C. Ratti, K. K. Szabo
Summary: This Letter introduces a new scheme for extrapolating the equation of state of QCD to finite chemical potential with improved convergence properties, allowing extension to high baryonic chemical potentials. The continuum extrapolated lattice results for the new expansion coefficients are presented, showing thermodynamic observables up to mu(B)/T <= 3.5. This novel expansion overcomes the limitations of traditional Taylor expansion methods, providing a solution to the poor signal-to-noise ratio in determining Taylor coefficients from lattice calculations.
PHYSICAL REVIEW LETTERS
(2021)
Article
Astronomy & Astrophysics
Szabolcs Borsanyi, Zoltan Fodor, Matteo Giordano, Jana N. Guenther, Sandor D. Katz, Attila Pasztor, Chik Him Wong
Summary: In order to understand the limitations of various approximation schemes, researchers compared them to direct results at finite baryon density, using reweighting techniques without an overlap problem. They calculated the equation of state of the quark gluon plasma and covered a wide range of baryochemical potential.
Article
Astronomy & Astrophysics
Matteo Giordano, Kornel Kapas, Sandor D. Katz, Attila Pasztor, Zoltan Tulipant
Summary: We investigate the 2+1-dimensional XY model at nonzero chemical potential on deformed integration manifolds, and present numerical evidence showing exponential reduction of the sign problem with respect to mu 2 and spatial volume. We also introduce a new approach to optimization based on reweighting to reduce computational cost.
Article
Astronomy & Astrophysics
Szabolcs Borsanyi, Jana N. Guenther, Ruben Kara, Zoltan Fodor, Paolo Parotto, Attila Pasztor, Claudia Ratti, Kalman Szabo
Summary: This study calculates a resummed equation of state using lattice QCD simulations with imaginary chemical potentials, and investigates the strangeness neutral state and the strangeness-to-baryon ratio.
Article
Astronomy & Astrophysics
Jana N. Guenther, Christian Hoelbling, Lukas Varnhorst
Summary: We present a method to study the semiclassical gravitational collapse of a radially symmetric scalar quantum field in a coherent initial state. The method maintains exact compatibility of the metric with the expectation values of the energy momentum tensor in the scalar field coherent state throughout the entire time evolution. By studying the collapse of a specific state, we observe the acceleration and radial outward movement of possible horizon formation, which is robust against various variations. Additionally, the method can be applied to the study of black hole evaporation and can be extended to higher angular momenta.
Article
Astronomy & Astrophysics
Szabolcs Borsanyi, Zoltan Fodor, Matteo Giordano, Sandor Katz, Daniel Nogradi, Attila Pasztor, Chik Him Wong
Summary: In this study, we simulate the QCD chiral transition using the sign-reweighting method on phenomenologically relevant lattices. This method overcomes the limitations of traditional approaches and provides a reliable way to study hot and dense matter.
Article
Astronomy & Astrophysics
Rene Bellwied, Claudia Ratti, Szabolcs Borsanyi, Paolo Parotto, Zoltan Fodor, Jana N. Guenther, Sandor D. Katz, Attila Pasztor, David Pesznyak, Kalman K. Szabo
Summary: Researchers used first principle lattice simulations to calculate corrections to the ideal HRG model and evaluated the fugacity expansion coefficients. By conducting a two-dimensional scan on the imaginary baryon number chemical potential and strangeness chemical potential plane, they successfully achieved their goal and reproduced the trend seen in experimental data.
Article
Astronomy & Astrophysics
Attila Pasztor, Zsolt Szep, Gergely Marko
Summary: A novel Bayesian method is proposed for analytically continuing observables to real baryochemical potential mu(B) in finite density QCD. By jointly analyzing Taylor coefficients and data at imaginary chemical potential mu(I)(B), an apparent convergence of rational functions [p/p] and [p/p + 1] sequences is observed with increasing p. The extrapolation up to mu(B) approximate to 600 MeV is presented.
Article
Physics, Nuclear
Mira Varma, Oliver K. Baker
Summary: In this letter, the authors expand upon the previous work to demonstrate the entanglement observed in top quark interactions. They propose that the thermal component caused by proton collisions with top quarks emerges from entanglement within the proton wave function, and they use published results to show the expected behavior.
Article
Physics, Nuclear
E. Ya. Paryev
Summary: In this study, we investigate the near-threshold meson photoproduction from protons and nuclei and explore the possibility of observing non-strange hidden-bottom pentaquark states through differential observables. We calculate the excitation functions and energy/momentum distributions for different production processes and propose that future experiments at high-luminosity electron-ion colliders could provide evidence for the existence of these hidden-bottom pentaquark resonances.
Article
Physics, Nuclear
M. Shariq Asnain, Manoj Kumar Sharma, Mohd. Shuaib, Aquib Siddique, Ishfaq Majeed Bhat, B. P. Singh, R. Prasad
Summary: This study validates the compound nucleus theory using heavy ion beams and different targets. By analyzing cross section data and comparing reaction cross section data, the study confirms the validity of the theory, but also observes discrepancies at lower excitation energies.
Article
Physics, Nuclear
Y. G. Yao, X. Y. Wu, H. Mei
Summary: This study presents a microscopic investigation of the electromagnetic properties of the low-lying states of single-A hypernucleus 9ABe using the HyperGCM method based on covariant density functional theory. The results are compared to those of a particle-rotor model (PRM) and show close agreement. It is found that the electric quadrupole transition strengths are more sensitive to the coupling strengths of the AN interaction than the magnetic moments and M 1 transition strengths.
