Laboratory For Fundamental Physics Research Articles

Measurement of gravity in laboratories for fundamental physics using mobile devices: An approach from the Internet of Things

AbstractIn this work, we present IoT, a freeware application for Android mobile devices that belongs to the remote laboratory platform called IoT.PhysicsSensor Mobile Edition. It incorporates the potentialities of the IoT to acquire, store, visualize, and analyze data using smartphones. This application, integrated into low‐cost hardware, can be used to conduct online and real‐time laboratory practices. Additionally, hundreds of users can be connected to the lab without limiting their participation due to the physical location or equipment available in the facilities. To test the capabilities of the architecture proposed in this work, a practice to measure the value for the acceleration of gravity from a free‐fall experience was designed. A group of 101 students from the Universidad Nacional de Colombia‐Sede Medellin and another of 63 students from Universidad Nacional de Colombia‐Sede de La Paz, Cesar, participated in the practice, thus obtaining results with a high degree of accuracy and precision and excellent reproducibility. This platform is emerging as a critical tool to face the digital transformation of educational environments, including those generated by the COVID‐19 pandemic.

Higher metal abundances do not solve the solar problem

Context. The Sun acts as a cornerstone of stellar physics. Thanks to spectroscopic, helioseismic and neutrino flux observations, we can use the Sun as a laboratory of fundamental physics in extreme conditions. The conclusions we draw are then used to inform and calibrate evolutionary models of all other stars in the Universe. However, solar models are in tension with helioseismic constraints. The debate on the ‘solar problem’ has hitherto led to numerous publications discussing potential issues with solar models and abundances. Aims. Using the recently suggested high-metallicity abundances for the Sun, we compute standard solar models as well as models with macroscopic transport that reproduce the solar surface lithium abundances, and we analyze their properties in terms of helioseismic and neutrino flux observations. Methods. We compute solar evolutionary models and combine spectroscopic and helioseismic constraints as well as neutrino fluxes to investigate the impact of macroscopic transport on these measurements. Results. When high-metallicity solar models are calibrated to reproduce the measured solar lithium depletion, tensions arise with respect to helioseismology and neutrino fluxes. This is yet another demonstration that the solar problem is also linked to the physical prescriptions of solar evolutionary models and not to chemical composition alone. Conclusions. A revision of the physical ingredients of solar models is needed in order to improve our understanding of stellar structure and evolution. The solar problem is not limited to the photospheric abundances if the depletion of light elements is considered. In addition, tighter constraints on the solar beryllium abundance will play a key role improving of solar models.

A glimpse of axion phenomenology in astrophysics

The old and successful idea of using astrophysical systems as laboratories for fundamental physics is becoming extremely popular nowadays. Axions are a remarkable example of Feebly Interacting Particles playing an important role in astrophysical phenomena. It is well-known that stars are powerful axion factories, giving strong constraints on their properties. Aspects of the axion phenomenology in horizontal-branch stars and supernovae are reviewed.

Topological Defects in Nematic Liquid Crystals: Laboratory of Fundamental Physics

Topological Defects The curvature of a closed manifold exhibiting orientational order has a strong impact on positions and the number of topological defects (TDs). The surface integrated Gaussian curvature determines the total winding number of TDs within the manifold. If a region possessing a large enough negative Gaussian curvature is introduced it can trigger pairs {defect, antidefect}, possessing opposite signs of the winding number. More details can be found in article number 2000752 by Mitja Kralj, Marko Kralj, and Samo Kralj.

Topological Defects in Nematic Liquid Crystals: Laboratory of Fundamental Physics

Topological defects (TDs) appear in all branches of physics due to the simplicity of generic mechanisms: The necessary condition for their existence is spontaneous symmetry breaking in a relevant physical field. Nematic liquid crystals (NLCs) represent an ideal testbed for their study and they can display point, line, textures, and in favorable conditions also wall defects. TDs in NLCs can be relatively easily created, controlled, and experimentally observed. This enables a detailed and controlled analysis of their physical properties, leading to the cross‐fertilization of knowledge among different areas of physics, including condensed matter, particle physics, and cosmology. Furthermore, TDs in NLCs could be exploited in diverse applications. Herein, some salient features of most common TDs in NLCs, their generic mechanisms, their importance for fundamental science, and possible applications based on them are illustrated.

Global Helioseismology

Helioseismology is one of the most successful fields of astrophysics. The observation and character-ization of solar oscillation has allowed solar seismologists to study the internal structure and dynamics of the Sun with unprecedented thoroughness. Ground-based networks and dedicated space missions have delivered data of exquisite quality, enabling the development of sophisticated inference techniques. The achievements of the fields count, amongst other, the determination of solar photospheric helium abundance, unacessible to spectroscopic constraints, the precise positioning of the base of the convective zone and the demonstration of the importance of microscopic diffusion in stellar radiative regions. Helioseismology played also a key role in validating the framework used to compute solar and stellar models and played an important role in the so-called solar neutrino problem. In the current era of astrophysics, with the increasing importance of asteroseismology to precisely characterize stars, the Sun still plays a crucial calibration role, acting as a benchmark for stellar models. With the revision of the solar abundances and the current discussions related to radiative opacity computations, the role of the Sun as a laboratory of fundamental physics is undisputable. In this brief review, I will discuss some of the inference techniques developed in the field of helioseismology, dedicated to the exploitation of the solar global oscillation modes.

Searching Ultra-compact Pulsar Binaries with Abnormal Timing Behavior

Abstract Ultra-compact pulsar binaries are both ideal sources of gravitational radiation for gravitational wave detectors and laboratories for fundamental physics. However, the shortest orbital period of all radio pulsar binaries is currently 1.6 hr. The absence of pulsar binaries with a shorter orbital period is most likely due to technique limit. This paper points out that a tidal effect occurring on pulsar binaries with a short orbital period can perturb the orbital elements and result in a significant change in orbital modulation, which dramatically reduces the sensitivity of the acceleration searching that is widely used. Here a new search is proposed. The abnormal timing residual exhibited in a single pulse observation is simulated by a tidal effect occurring on an ultra-compact binary. The reproduction of the main features represented by the sharp peaks displayed in the abnormal timing behavior suggests that pulsars like PSR B0919+06 could be a candidate for an ultra-compact binary of an orbital period of ∼10 minutes and a companion star of a white dwarf star. The binary nature of such a candidate is further tested by (1) comparing the predicted long-term binary effect with decades of timing noise observed and (2) observing the optical counterpart of the expected companion star. Test (1) likely supports our model, while more observations are needed in test (2). Some interesting ultra-compact binaries could be found in the near future by applying such a new approach to other binary candidates.

The relativistic pulsar-white dwarf binary PSR J1738+0333 - I. Mass determination and evolutionary history

PSR J1738+0333 is one of the four millisecond pulsars known to be orbited by a white dwarf companion bright enough for optical spectroscopy. Of these, it has the shortest orbital period, making it especially interesting for a range of astrophysical and gravity related questions. We present a spectroscopic and photometric study of the white dwarf companion and infer its radial velocity curve, effective temperature, surface gravity and luminosity. We find that the white dwarf has properties consistent with those of low-mass white dwarfs with thick hydrogen envelopes, and use the corresponding mass-radius relation to infer its mass; M_WD = 0.181 +/- +0.007/-0.005 solar masses. Combined with the mass ratio q=8.1 +/- 0.2 inferred from the radial velocities and the precise pulsar timing ephemeris, the neutron star mass is constrained to M_PSR = 1.47 +/- +0.07/-0.06 solar masses. Contrary to expectations, the latter is only slightly above the Chandrasekhar limit. We find that, even if the birth mass of the neutron star was only 1.20 solar masses, more than 60% of the matter that left the surface of the white dwarf progenitor escaped the system. The accurate determination of the component masses transforms this system in a laboratory for fundamental physics by constraining the orbital decay predicted by general relativity. Currently, the agreement is within 1 sigma of the observed decay. Further radio timing observations will allow precise tests of white dwarf models, assuming the validity of general relativity.

Dense stellar systems as laboratories for fundamental physics

Galactic nuclei and globular clusters act as laboratories in which nature experiments with normal stars, neutron stars and black holes, through collisions and through the formation of bound states, in the form of binaries. The main difference with the usual Earth-based laboratories is that we cannot control the experiments. Instead, we have no choice but to create virtual laboratories on Earth, in order to simulate all the relevant physics in large-scale computational experiments. This implies a realistic treatment of stellar dynamics, stellar evolution, and stellar hydrodynamics. Each of these three fields has its own legacy codes, workhorses that are routinely used to simulate star clusters, stars, and stellar collisions, respectively. I outline the main steps that need to be taken in order to embed and where needed transform these legacy codes in order to produce a far more modular and robust environment for modeling dense stellar systems. The time is right to do so: within a few years computers will reach the required speed, in the Petaflops range, to follow a star cluster with a million stars for 10 billion years, while resolving the internal binary and multiple star motions. By that time simulation software will be the main bottleneck in our ability to analyze dense stellar systems. Only through full-scale simulations will we be able to critically test our understanding of the ‘microphysics’ of stellar collisions and their aftermath, in a direct comparison with observations.

Strong fields and recycled accelerator parts as a laboratory for fundamental physics

Over the last few years it has become increasingly clear that low energy, but high precision experiments provide a powerful and complementary window to physics beyond the Standard Model. In this note we illuminate this by using minicharged particles as an example. We argue that minicharged particles arise naturally in extensions of the Standard Model. Compatibility with charge quantization arguments suggests that minicharged particles typically arise together with a massless hidden sector U(1) gauge field. We present several low energy experiments employing strong lasers, electric and magnetic fields that can be used to search for (light) minicharged particles and their accompanying U(1) gauge boson.

Recycled binary pulsars—a most precise laboratory of fundamental physics

We discuss here the problems connected with radio pulsars in close binary systems, which have an anomalously small magnetic field and rotate very rapidly. The first discovered Hulse–Taylor binary pulsar permitted us to make the indirect discovery of gravitational waves. Later single recycled pulsars (RPs) that had been in binaries before the disruption of the pairs were found. The mechanism of the pair disruption and the formation of a single RP is considered on the basis of the mechanism of enhanced evaporation. General relativity effects in the pairs connecting two neutron stars (NSs) and, in particular, in a double-pulsar system are considered. Timing observations of NS+NS binary pulsars provide a unique means of checking general relativity and the variability of the gravitational constant.

Terascale input physics: the role of nuclear electron capture in core collapse supernovae

Core Collapse supernovae are among the most energetic explosions in the Universe and the predominant source of chemical elements heavier than carbon. They drive matter to extremes of density and temperature that cannot be produced on Earth and serve as laboratories for fundamental physics. Understanding these events requires the partnership of nuclear and particle physicists with astrophysicists and computational scientists. A case in point is the study of the role that captures of electrons and neutrinos on atomic nuclei play during the collapse of the core of a massive star as it reaches the end of its life. In addition to the astrophysical modeling, the required understanding of the structure of the atomic nucleus is itself a terascale application. We will discuss recent work which shows that a realistic treatment of electron capture on these nuclei causes significant changes in the hydrodynamics of core collapse and bounce, which set the stage for the subsequent evolution of the supernova.

Stars as laboratories for fundamental physics: the astrophysics of neutrinos, axions, and other weakly interacting particles

Preface Acknowledgments 1: The Energy-Loss Argument 2: Anomalous Stellar Energy Losses Bounded by Observations 3: Particles Interacting with Electrons and Baryons 4: Processes in a Nuclear Medium 5: Two-Photon Coupling of Low-Mass Bosons 6: Particle Dispersion and Decays in Media 7: Nonstandard Neutrinos 8: Neutrino Oscillations 9: Oscillations of Trapped Neutrinos 10: Solar Neutrinos 11: Supernova Neutrinos 12: Radiative Particle Decays from Distant Sources 13: What Have We Learned from SN 1987A? 14: Axions 15: Miscellaneous Exotica 16: Neutrinos: The Bottom Line App. A. Units and Dimensions App. B. Neutrino Coupling Constants App. C. Numerical Neutrino Energy-Loss Rates App. D. Characteristics of Stellar Plasmas References Acronyms Symbols Subject Index

Neutrino Questions: Stars as Laboratories for Fundamental Physics.

Neutrino Questions: Stars as Laboratories for Fundamental Physics.

Stars as laboratories for fundamental physics

Stars as laboratories for fundamental physics