Recent ucsd_physics items

Solving Einstein’s equation numerically on manifolds with nonorientable spatial slices

Thu, 18 Jun 2026 00:00:00 +0000

This paper presents solutions to Einstein’s equation, and the numerical methods used to construct them, that describe simple cosmological models on manifolds with compact nonorientable spatial slices. These solutions have been constructed on a selection of manifolds having positive, negative, and vanishing spatial scalar curvatures. One example is shown to be indistinguishable locally from a homogeneous Friedman cosmological model, and others are constructed with significant inhomogeneities. Together, these examples are used to explore the strengths and limitations of the numerical methods used in this study, and to test the code used to implement them.

Track reconstruction as a service for collider physics

Wed, 17 Jun 2026 00:00:00 +0000

Optimizing charged-particle track reconstruction algorithms is crucial for efficient event reconstruction in Large Hadron Collider (LHC) experiments due to their significant computational demands. Existing track reconstruction algorithms have been adapted to run on massively parallel coprocessors, such as graphics processing units (GPUs), to reduce processing time. Nevertheless, challenges remain in fully harnessing the computational capacity of coprocessors in a scalable and non-disruptive manner. This paper proposes an inference-as-a-service approach for particle tracking in high energy physics experiments. To evaluate the efficacy of this approach, two distinct tracking algorithms are tested: Patatrack, a rule-based algorithm, and Exa.TrkX, a machine learning-based algorithm. The as-a-service implementations show enhanced GPU utilization and can process requests from multiple CPU cores concurrently without increasing per-request latency. The impact of data transfer is minimal...

Future Circular Collider Feasibility Study Report

Wed, 3 Jun 2026 00:00:00 +0000

Volume 1 of the FCC Feasibility Report presents an overview of the physics case, experimental programme, and detector concepts for the Future Circular Collider (FCC). This volume outlines how FCC would address some of the most profound open questions in particle physics, from precision studies of the Higgs and EW bosons and of the top quark, to the exploration of physics beyond the Standard Model. The report reviews the experimental opportunities offered by the staged implementation of FCC, beginning with an electron-positron collider (FCC-ee), operating at several centre-of-mass energies, followed by a hadron collider (FCC-hh). Benchmark examples are given of the expected physics performance, in terms of precision and sensitivity to new phenomena, of each collider stage. Detector requirements and conceptual designs for FCC-ee experiments are discussed, as are the specific demands that the physics programme imposes on the accelerator in the domains of the calibration of the collision...

Measurement of the inclusive-isolated prompt-photon cross section in pp¯ collisions using the full CDF data set

Wed, 3 Jun 2026 00:00:00 +0000

A measurement of the inclusive production cross section of isolated prompt photons in proton-antiproton collisions at center-of-mass energy s=1.96 TeV is presented. The results are obtained using the full Run II data sample collected with the Collider Detector at the Fermilab Tevatron, which corresponds to an integrated luminosity of 9.5 fb-1. The cross section is measured as a function of photon transverse energy, ETγ, in the range 30

pc-Gravity as a geometric resolution of the black hole information paradox

Tue, 19 May 2026 00:00:00 +0000

We investigate the black hole information paradox in the setting of pseudo-complex gravity, a covariant geometric extension of general relativity that introduces a minimal length scale by deforming the spacetime manifold. In this framework, curvature invariants stay finite, and the classical singularity is geometrically regularized via a smooth core. We show that the correction term B/(6r4) alters the Schwarzschild metric, generating the regularized geometry above, yielding a finite Hawking temperature, and inducing subleading corrections to the Bekenstein–Hawking entropy. Crucially, we demonstrate that the pseudo-complex geometric structure obstructs a clean factorization of the Hilbert space into interior and exterior regions, thereby removing the key assumption behind the standard derivation of the paradox. This structural reinterpretation of entanglement flow offers a new geometric route to unitarity preservation and information recovery. We examine the resulting effects on...

The pseudo-complex FLRW model and the time evolution of the Hubble parameter

Tue, 19 May 2026 00:00:00 +0000

The pseudo-complex version of the Friedmann–Lemaître–Robertson–Walker model (pcFLRW) is presented within the framework of pseudo-complex General Relativity (pcGR). In this approach, dark energy emerges as a geometric consequence of the pseudo-complex structure, leading to a specific functional form for the Hubble parameter H(z) characterized by a single geometric parameter β$$\beta $$. This parameter governs the effective dark-energy equation of state via pΛ=-βεΛ$$p_\Lambda = -\beta \varepsilon _\Lambda $$ and is directly linked to the present-day time derivative of the Hubble parameter through H˙0=32(β-1)H02$$\dot{H}_0 = \frac{3}{2}(\beta -1)H_0^2$$. Using recent DESI BAO data, we constrain β=1.0426±0.0144$$\beta = 1.0426 \pm 0.0144$$, which yields a positive H˙0≃(0.94±0.32)×10-17(km/s2)/Mpc$$\dot{H}_0 \simeq (0.94 \pm 0.32)\times 10^{-17}\,\mathrm {(km/s^2)/Mpc}$$. This contrasts with the Λ$$\Lambda $$CDM prediction, where H˙0$$\dot{H}_0$$ is negative (H˙0≈-0.45H02$$\dot{H}_0...

Rotating strange dwarfs and their indistinguishability from white dwarfs

Tue, 19 May 2026 00:00:00 +0000

We investigate the structure of strange dwarfs, modeled as hybrid compact stars composed of a self bound strange quark matter core surrounded by a white dwarf like crust, within a fully relativistic framework. Static configurations are constructed by solving the Tolman Oppenheimer Volkoff equations, and uniformly rotating configurations are modeled within the Hartle-Thorne slow rotation expansion (to O(Ω2)$$\mathcal{O}(\Omega ^2)$$). We therefore interpret results at large fractional spins conservatively, and use the Kepler frequency mainly as a reference scale for comparing different masses and models. The stellar matter is described using a hybrid equation of state, in which the crust is modeled by a degenerate electron-ion system and the core by the MIT Bag Model. By comparing strange dwarfs with conventional white dwarfs across a range of rotation rates, we show that rotation inflates the radius and can reduce (in a quantifiable way) the separation between the two families...

Anisotropic Compact Stars: Theory and Simulation from Microphysical Models to Macroscopic Structure and Observables

Tue, 19 May 2026 00:00:00 +0000

Strong magnetic fields and anisotropic stresses can substantially modify the structure and observable properties of compact stars. In this review, we present a unified treatment of magnetically induced anisotropy across neutron stars, hybrid stars, and white dwarfs, connecting the microphysical equation of state effects to macroscopic structure and multimessenger observables. We demonstrate that magnetic-field geometry plays a decisive role: toroidally oriented (transverse) fields enhance the maximum mass by providing additional perpendicular pressure support, whereas radially oriented fields primarily increase central compression with comparatively small mass gain. In neutron stars, anisotropy and magnetic stresses can shift phase-transition thresholds in hybrid models and enable configurations in the lower mass gap with significantly smaller magnetic energy compared to the gravitational binding energy. We further show that continuous gravitational wave emission from magnetically...

Unconventionally sharp dynamic resonances from a disordered Wigner crystal