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Spontaneously broken (-1)-form U(1) symmetries 自发破缺的 (-1)-form U(1) 对称性
IF 5.5 2区 物理与天体物理
SciPost Physics Pub Date : 2024-08-01 DOI: 10.21468/scipostphys.17.2.031
Daniel Aloni, Eduardo García-Valdecasas, Matthew Reece, Motoo Suzuki
{"title":"Spontaneously broken (-1)-form U(1) symmetries","authors":"Daniel Aloni, Eduardo García-Valdecasas, Matthew Reece, Motoo Suzuki","doi":"10.21468/scipostphys.17.2.031","DOIUrl":"https://doi.org/10.21468/scipostphys.17.2.031","url":null,"abstract":"Spontaneous breaking of symmetries leads to universal phenomena. We extend this notion to $(-1)$-form U(1) symmetries. The spontaneous breaking is diagnosed by a dependence of the vacuum energy on a constant background field $theta$, which can be probed by the topological susceptibility. This leads to a reinterpretation of the Strong CP problem as arising from a spontaneously broken instantonic symmetry in QCD. We discuss how known solutions to the problem are unified in this framework and explore some, so far unsuccessful, attempts to find new solutions.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"24 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141884614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Critical loop models are exactly solvable 临界环模型完全可解
IF 5.5 2区 物理与天体物理
SciPost Physics Pub Date : 2024-08-01 DOI: 10.21468/scipostphys.17.2.029
Rongvoram Nivesvivat, Sylvain Ribault, Jesper Lykke Jacobsen
{"title":"Critical loop models are exactly solvable","authors":"Rongvoram Nivesvivat, Sylvain Ribault, Jesper Lykke Jacobsen","doi":"10.21468/scipostphys.17.2.029","DOIUrl":"https://doi.org/10.21468/scipostphys.17.2.029","url":null,"abstract":"In two-dimensional critical loop models, including the O(n) and Potts models, the spectrum is exactly known, as are a few structure constants or ratios thereof. Using numerical conformal bootstrap methods, we study 235 of the simplest 4-point structure constants. For each structure constant, we find an analytic expression as a product of two factors: 1) a universal function of conformal dimensions, built from Barnes' double Gamma function, and 2) a polynomial function of loop weights, whose degree obeys a simple upper bound. We conjecture that all structure constants are of this form. For a few 4-point functions, we build corresponding observables in a lattice loop model. From numerical lattice results, we extract amplitude ratios that depend neither on the lattice size nor on the lattice coupling. These ratios agree with the corresponding ratios of 4-point structure constants.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"64 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141884613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Beyond universality in repulsive SU(N) Fermi gases 超越排斥性 SU(N) 费米气体的普遍性
IF 5.5 2区 物理与天体物理
SciPost Physics Pub Date : 2024-08-01 DOI: 10.21468/scipostphys.17.2.030
Jordi Pera, Joaquim Casulleras, Jordi Boronat
{"title":"Beyond universality in repulsive SU(N) Fermi gases","authors":"Jordi Pera, Joaquim Casulleras, Jordi Boronat","doi":"10.21468/scipostphys.17.2.030","DOIUrl":"https://doi.org/10.21468/scipostphys.17.2.030","url":null,"abstract":"Itinerant ferromagnetism in dilute Fermi gases is predicted to emerge at values of the gas parameter where second-order perturbation theory is not accurate enough to properly describe the system. We have revisited perturbation theory for SU(N) fermions and derived its generalization up to third order both in terms of the gas parameter and the polarization. Our results agree satisfactorily with quantum Monte Carlo results for hard-sphere and soft-sphere potentials for $S = 1/2$. Although the nature of the phase transition depends on the interaction potential, we find that for a hard-sphere potential a phase transition is guaranteed to occur. While for $S= 1/2$ we observe a quasi-continuous transition, for spins $3/2$ and $5/2$, a first-order phase transition is found. For larger spins, a double transition (combination of continuous and discontinuous) occurs. The critical density reduces drastically when the spin increases, making the phase transition more accessible to experiments with ultracold dilute Fermi gases. Estimations for Fermi gases of Yb and Sr with spin $5/2$ and $9/2$, respectively, are reported.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"5 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141884618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Bound impurities in a one-dimensional Bose lattice gas: Low-energy properties and quench-induced dynamics 一维玻色晶格气体中的结合杂质：低能特性和淬火诱导动力学
IF 5.5 2区 物理与天体物理
SciPost Physics Pub Date : 2024-07-31 DOI: 10.21468/scipostphyscore.7.3.049
Felipe Isaule, Abel Rojo-Francàs, Bruno Juliá-Díaz
{"title":"Bound impurities in a one-dimensional Bose lattice gas: Low-energy properties and quench-induced dynamics","authors":"Felipe Isaule, Abel Rojo-Francàs, Bruno Juliá-Díaz","doi":"10.21468/scipostphyscore.7.3.049","DOIUrl":"https://doi.org/10.21468/scipostphyscore.7.3.049","url":null,"abstract":"We study two mobile bosonic impurities immersed in a one-dimensional optical lattice and interacting with a bosonic bath. We employ the exact diagonalization method for small periodic lattices to study stationary properties and dynamics. We consider the branch of repulsive interactions that induce the formation of bound impurities, akin to the bipolaron problem. A comprehensive study of ground-state and low-energy properties is presented, including an examination of the interaction strengths which induce the formation of a bound dimer of impurities. We also study the dynamics induced after an interaction quench to examine the stability of the bound dimers. We reveal that after large interaction quenches from strong to weak interactions the system can show large oscillations over time with revivals of the dimer states. We find that the oscillations are driven by selected eigenstates with phase-separated configurations.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"43 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141868578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
LiHoF4 as a spin-half non-standard quantum Ising system 作为自旋半非标准量子伊辛系统的 LiHoF4
IF 5.5 2区 物理与天体物理
SciPost Physics Pub Date : 2024-07-31 DOI: 10.21468/scipostphys.17.1.028
Tomer Dollberg, Moshe Schechter
{"title":"LiHoF4 as a spin-half non-standard quantum Ising system","authors":"Tomer Dollberg, Moshe Schechter","doi":"10.21468/scipostphys.17.1.028","DOIUrl":"https://doi.org/10.21468/scipostphys.17.1.028","url":null,"abstract":"LiHoF$_{4}$ is a magnetic material known for its Ising-type anisotropy, making it a model system for studying quantum magnetism. However, the theoretical description of LiHoF$_{4}$ using the quantum Ising model has shown discrepancies in its phase diagram, particularly in the regime dominated by thermal fluctuations. In this study, we investigate the role of off-diagonal dipolar terms in LiHoF$_{4}$, previously neglected, in determining its properties. We analytically derive the low-energy effective Hamiltonian of LiHoF$_{4}$, including the off-diagonal dipolar terms perturbatively, both in the absence and presence of a transverse field. Our results encompass the full boldmath{$B_{x}-T$} phase diagram, confirming the significance of the off-diagonal dipolar terms in reducing the zero-field critical temperature and determining the critical temperature's dependence on the transverse field. We also highlight the sensitivity of this mechanism to the crystal structure by comparing our calculations with the Fe$_{8}$ system.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"1 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141868408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The NFLikelihood: An unsupervised DNNLikelihood from normalizing flows NFLikelihood：无监督 DNNLikelihood（来自归一化流量的概率
IF 5.5 2区 物理与天体物理
SciPost Physics Pub Date : 2024-07-31 DOI: 10.21468/scipostphyscore.7.3.048
Humberto Reyes-González, Riccardo Torre
{"title":"The NFLikelihood: An unsupervised DNNLikelihood from normalizing flows","authors":"Humberto Reyes-González, Riccardo Torre","doi":"10.21468/scipostphyscore.7.3.048","DOIUrl":"https://doi.org/10.21468/scipostphyscore.7.3.048","url":null,"abstract":"We propose the NFLikelihood, an unsupervised version, based on Normalizing Flows, of the DNNLikelihood proposed in [Eur. Phys. J. C 80, 664 (2020)]. We show, through realistic examples, how Autoregressive Flows, based on affine and rational quadratic spline bijectors, are able to learn complicated high-dimensional Likelihoods arising in High Energy Physics (HEP) analyses. We focus on a toy LHC analysis example already considered in the literature and on two Effective Field Theory fits of flavor and electroweak observables, whose samples have been obtained through the HEPFit code. We discuss advantages and disadvantages of the unsupervised approach with respect to the supervised one and discuss a possible interplay between the two.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"51 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141868577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Analytic thermodynamic properties of the Lieb-Liniger gas 列布-里尼格气体的热力学性质分析
IF 5.5 2区 物理与天体物理
SciPost Physics Pub Date : 2024-07-30 DOI: 10.21468/scipostphyscore.7.3.047
Matthew L. Kerr, Giulia De Rosi, Karen Kheruntsyan
{"title":"Analytic thermodynamic properties of the Lieb-Liniger gas","authors":"Matthew L. Kerr, Giulia De Rosi, Karen Kheruntsyan","doi":"10.21468/scipostphyscore.7.3.047","DOIUrl":"https://doi.org/10.21468/scipostphyscore.7.3.047","url":null,"abstract":"We present a comprehensive review on the state-of-the-art of the approximate analytic approaches describing the finite-temperature thermodynamic quantities of the Lieb-Liniger model of the one-dimensional (1D) Bose gas with contact repulsive interactions. This paradigmatic model of quantum many-body-theory plays an important role in many areas of physics-thanks to its integrability and possible experimental realization using, e.g., ensembles of ultracold bosonic atoms confined to quasi-1D geometries. The thermodynamics of the uniform Lieb-Liniger gas can be obtained numerically using the exact thermal Bethe ansatz (TBA) method, first derived in 1969 by Yang and Yang. However, the TBA numerical calculations do not allow for the in-depth understanding of the underlying physical mechanisms that govern the thermodynamic behavior of the Lieb-Liniger gas at finite temperature. Our work is then motivated by the insights that emerge naturally from the transparency of closed-form analytic results, which are derived here in six different regimes of the gas and which exhibit an excellent agreement with the TBA numerics. Our findings can be further adopted for characterising the equilibrium properties of inhomogeneous (e.g., harmonically trapped) 1D Bose gases within the local density approximation and for the development of improved hydrodynamic theories, allowing for the calculation of breathing mode frequencies which depend on the underlying thermodynamic equation of state. Our analytic approaches can be applied to other systems including impurities in a quantum bath, liquid helium-4, and ultracold Bose gas mixtures.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"67 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141868462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Phonon pumping by modulating the ultrastrong vacuum 通过调节超强真空进行声子抽运
IF 5.5 2区 物理与天体物理
SciPost Physics Pub Date : 2024-07-30 DOI: 10.21468/scipostphys.17.1.027
Fabrizio Minganti, Alberto Mercurio, Fabio Mauceri, Marco Scigliuzzo, Salvatore Savasta, Vincenzo Savona
{"title":"Phonon pumping by modulating the ultrastrong vacuum","authors":"Fabrizio Minganti, Alberto Mercurio, Fabio Mauceri, Marco Scigliuzzo, Salvatore Savasta, Vincenzo Savona","doi":"10.21468/scipostphys.17.1.027","DOIUrl":"https://doi.org/10.21468/scipostphys.17.1.027","url":null,"abstract":"The vacuum (i.e., the ground state) of a system in ultrastrong light-matter coupling contains particles that cannot be emitted without any dynamical perturbation and is thus called virtual. We propose a protocol for inducing and observing real mechanical excitations of a mirror enabled by the virtual photons in the ground state of a tripartite system, where a resonant optical cavity is ultrastrongly coupled to a two-level system (qubit) and, at the same time, optomechanically coupled to a mechanical resonator. Real phonons are coherently emitted when the frequency of the two-level system is modulated at a frequency comparable to that of the mechanical resonator and, therefore much lower than the optical frequency. We demonstrate that this hybrid effect is a direct consequence of the virtual photon population in the ground state. Within a classical physics analogy, attaching a weight to a spring only changes its resting position, whereas dynamically modulating the weight makes the system oscillate. In our case, however, the weight is the vacuum itself. We propose and accurately characterize a hybrid superconducting-optomechanical setup based on available state-of-the-art technology, where this effect can be experimentally observed.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"212 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141868334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Combining QED and approximate ${rm N}^3$LO QCD corrections in a global PDF fit: MSHT20qed_an3lo PDFs 在全局PDF拟合中结合QED和近似${rm N}^3$LO QCD修正：MSHT20qed_an3lo PDFs
IF 5.5 2区 物理与天体物理
SciPost Physics Pub Date : 2024-07-30 DOI: 10.21468/scipostphys.17.1.026
Thomas Cridge, Lucian A. Harland-Lang, Robert S. Thorne
{"title":"Combining QED and approximate ${rm N}^3$LO QCD corrections in a global PDF fit: MSHT20qed_an3lo PDFs","authors":"Thomas Cridge, Lucian A. Harland-Lang, Robert S. Thorne","doi":"10.21468/scipostphys.17.1.026","DOIUrl":"https://doi.org/10.21468/scipostphys.17.1.026","url":null,"abstract":"We present the MSHT20qed_an3lo parton distribution functions (PDFs). These result from the first global PDF analysis to combine QED and approximate $N^3$LO (a$N^3$LO) QCD corrections in the theoretical calculation of the PDF evolution and cross sections entering the fit. We examine the PDF impact, and find that the effect of QED is relatively mild in comparison to the a$N^3$LO corrections, although it should still be accounted for at the level of precision now required. These QED corrections are in addition found to roughly factorise from the QCD corrections; that is, their relative impact on the PDFs is roughly the same at NNLO and a$N^3$LO. The fit quality exhibits a very small deterioration at a$N^3$LO upon the inclusion of QED corrections, which is rather smaller than the deterioration observed at NNLO in QCD. The impact on several cross-sections at $N^3$LO is also examined, including the Higgs cross sections at $N^3$LO. Finally, a LO in QCD fit that includes QED corrections is also presented: the MSHT20qed_an3lo set.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"25 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141868331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Transport of orbital currents in systems with strong intervalley coupling: The case of Kekulé distorted graphene 具有强间隔耦合的系统中的轨道电流传输：凯库勒扭曲石墨烯的情况
IF 5.5 2区 物理与天体物理
SciPost Physics Pub Date : 2024-07-30 DOI: 10.21468/scipostphyscore.7.3.046
Tarik P. Cysne, R. B. Muniz, Tatiana G. Rappoport
{"title":"Transport of orbital currents in systems with strong intervalley coupling: The case of Kekulé distorted graphene","authors":"Tarik P. Cysne, R. B. Muniz, Tatiana G. Rappoport","doi":"10.21468/scipostphyscore.7.3.046","DOIUrl":"https://doi.org/10.21468/scipostphyscore.7.3.046","url":null,"abstract":"We show that orbital currents can describe the transport of orbital magnetic moments of Bloch states in models where the formalism based on valley current is not applicable. As a case study, we consider Kekulé-$O$ distorted graphene. We begin by analyzing the band structure in detail and obtain the intrinsic orbital magnetic moment operator of Bloch states for this model. Despite the simultaneous presence of time-reversal and spatial-inversion symmetries, such operator may be defined, although its expectation value at a given energy is zero. Nevertheless, its presence can be exposed by the application of an external magnetic field. We then proceed to study the transport of these quantities. In the Kekulé-$O$ distorted graphene model, the strong coupling between different valleys prevents the definition of a bulk valley current. However, the formalism of the orbital Hall effect together with the non-Abelian description of the magnetic moment operator can be directly applied to describe its transport in these types of models. We show that the Kekulé-$O$ distorted graphene model exhibits an orbital Hall insulating plateau whose height is inversely proportional to the energy band gap produced by intervalley coupling. Our results strengthen the perspective of using the orbital Hall effect formalism as a preferable alternative to the valley Hall effect approach.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"38 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141868464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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