Beyond the Usual: Observing Fractional Fermi Seas in a Quantum Gas

Researchers have experimentally created and observed fractional Fermi seas – a novel quantum state of matter – within a one-dimensional Bose gas, opening new avenues for understanding interacting quantum systems.
![Calculations of particle distribution functions-specifically for muons, photons, and a [latex]Z^{\prime}[/latex] boson, considering transverse and longitudinal polarizations-demonstrate deviations from Standard Model predictions, offering insights into new physics beyond established parameters and factorization scales.](https://arxiv.org/html/2602.16771v1/x1.png)
![String configurations in five dimensions reveal distinct behaviors dependent on connectivity, with a turning point coordinate [latex]r_0[/latex] characterizing connected states and a light quark coordinate [latex]r_{\bar{q}}[/latex] defining disconnected configurations at [latex]y=0[/latex] and [latex]y=Y[/latex].](https://arxiv.org/html/2602.16657v1/x2.png)
![The path integral formalism, as illustrated by [latex]Eq. (12)[/latex], establishes boundary conditions at [latex]\tau = 0[/latex] through reference bra states, while the inclusion of decoherence-modeled by interactions coupling [latex]\phi_i[/latex] and [latex]\bar{\phi}_i[/latex] at [latex]\tau = 0[/latex]-captures the system’s loss of quantum coherence.](https://arxiv.org/html/2602.16597v1/Fig1.png)
![The study demonstrates a method for stacking daily modulation data over a sidereal year-366 days-by tracking the rate [latex]R(t)[/latex] against both sidereal time and a shifted variant [latex]\tilde{t}[/latex], revealing that while [latex]R(t)[/latex] fluctuates within a defined envelope throughout the year, specific rates on January 1st and May 16th serve as key reference points for characterizing this temporal modulation.](https://arxiv.org/html/2602.15947v1/x3.png)
![The study of heavy-ion collisions at [latex]\sqrt{s_{NN}} = 19.6[/latex] GeV reveals how fluctuations in transverse momentum-measured through observables like [latex]\langle p_T \rangle[/latex], [latex]v_0 = \sigma_{p_T} / \langle p_T \rangle[/latex], [latex]R_{p_T}[/latex], and [latex]r_{p_T}[/latex]-differ for pions, kaons, and protons, suggesting that baryon diffusion-represented by parameters [latex]C_B = 0.0[/latex] and [latex]C_B = 0.5[/latex]-influences particle production in these high-energy events, a phenomenon further corroborated by comparative data from 5-10% centrality measurements.](https://arxiv.org/html/2602.16369v1/x4.png)
![The study demonstrates that for a rapidly spinning black hole with [latex] a_{\*} = 0.99 [/latex] and maximal deformation [latex] \ell_{\textrm{NP}} = 0.1137 [/latex], the horizon radius [latex] r_H(\theta) [/latex] deviates from that of a Kerr black hole, and the innermost stable circular orbit (ISCO) radius [latex] r_{\textrm{ISCO}} [/latex] is significantly altered as a function of spin and deformation-with parameter combinations leading to naked singularities excluded from the analysis.](https://arxiv.org/html/2602.16562v1/x2.png)