Analysis and results of a direct measurement of the cosmic-ray proton spectrum with the CALET instrument onboard the International Space Station, including the detailed assessment of systematic uncertainties. The observation period used in this analysis is from October 13, 2015 to August 31, 2018.
Param Singh edited a focus issue "Applications of loop quantum gravity to cosmology" for Classical and Quantum Gravity
Param Singh, edited a special issue on "Applications of loop quantum gravity to cosmology" for Classical and Quantum Gravity, the premier journal for gravitational physics community. The special issue had original research articles on resolution of gravitational singularities, observational signatures of loop quantum gravity and various aspects of quantum cosmology by many prominent researchers in the field, including Abhay Ashtekar, Eberly Chair of Physics at the Pennsylvania State University, and Ivan Agullo and Peter Diener at LSU. Param Singh was then invited to write a popular article highlighting this special issue in Classical and Quantum Gravity's website CQG+.
For the first time, scientists have directly detected gravitational waves — ripples in space and time — in addition to light from the spectacular collision of two neutron stars. This marks the first time that a cosmic event has been viewed in both gravitational waves and light. The discovery was made using the U.S.-based Laser Interferometer Gravitational-Wave Observatory, or LIGO; the Europe-based Virgo detector; and some 70 ground- and space-based observatories. Read More
LSU Physicist’s Research Reveals that the Most Energetic Particles in the Cosmos Originated from Outside our Galaxy
In a paper published in the journal Science, the Pierre Auger Collaboration reports
observational evidence demonstrating that cosmic rays with energies a million times
greater than that of the protons accelerated in the Large Hadron Collider come from
much further away than from our galaxy.
Professor Jim Matthews, former co-spokesperson of the Auger Collaboration, works with more than 500 scientists from 17 countries on the world’s leading science project for the exploration of the highest energy cosmic rays to elucidate the origins and properties of the most energetic particles in the Universe. The collaboration is reconstructing the path of the Universe's most energetic cosmic rays, bringing new insights into the origin and nature of this intergalactic phenomenon. Read More
CALET (CALorimetric Electron Telescope), a Japan-Italy-US experiment on the International Space Station (ISS), has successfully carried out a high-precision measurement of the cosmic ray electron spectrum up to 3 tera electron volts (TeV). This experiment, based on two years of data taken on the Exposed Facility on the ISS, is the first to make direct measurements of such high energy electrons in space. The CALET team published its first results in Physical Review Letters November 1 (O. Ariadne et al., Physical Review Letters 119, 181101, 2017). The measured spectrum provides a hint of a feature in the high energy spectrum that may be due to a nearby high energy source (e.g., a pulsar) or the annihilation of dark matter particles. CALET expects to take data on the ISS for an additional 3 years, and increase its current statistics by approximately a factor of 6. Read More
Kristina Launey published a book "Emergent Phenomena in Atomic Nuclei from Large-Scale Modeling: A Symmetry-Guided Perspective"
This book is a unique collection of reviews that discuss emergent phenomena in the world of protons and neutrons, and that of quarks and gluons, as viewed from first principles, microscopic considerations, and analysis of experimental data. A special theme resonates throughout the book: the important role of symmetries, exact and approximate, in exposing emergent features and guiding large-scale nuclear modeling, such as Lattice Quantum Chromodynamics, Effective Field Theory, Ab Initio Models, Quantum Monte Carlo Methods, and Density Functional Theory.
The Laser Interferometer Gravitational-wave Observatory, or LIGO, has made a third detection of gravitational waves, which are ripples in space and time, demonstrating that a new window in astronomy has been firmly opened. As was the case with the first two detections, the waves were generated when two black holes collided to form a larger black hole. Read More
Jorge Pullin co-edited a book "Loop quantum gravity: the first 30 years"
Jorge Pullin has co-edited with Abhay Ashtekar, the Eberly Chair of Physics at the Pennsylvania State University, the volume "Loop quantum gravity: the first 30 years". It includes eight chapters by young emerging leaders of the field providing a snapshot of its state of the art, including one by LSU's Ivan Agullo and Parampreet Singh. The book is part of the series that World Scientific Publishing Co. of Singapore is putting out to celebrate the 100 years of Einstein's General Theory of Relativity. According to the publisher, It will include "two dozen excellent monographs written by top-notch authors from the international gravitational community".
Mark Wilde's Second Edition of his book "Quantum Information Theory" has been published.
Developing many of the major, exciting, pre- and post-millennium developments from the ground up, this book is an ideal entry point for graduate students into quantum information theory. Significant attention is given to quantum mechanics for quantum information theory, and careful studies of the important protocols of teleportation, superdense coding, and entanglement distribution are presented. In this new edition, readers can expect to find over 100 pages of new material, including detailed discussions of Bell's theorem, the CHSH game, Tsirelson's theorem, the axiomatic approach to quantum channels, the definition of the diamond norm and its interpretation, and a proof of the Choi–Kraus theorem. Discussion of the importance of the quantum dynamic capacity formula has been completely revised, and many new exercises and references have been added. This new edition will be welcomed by the upcoming generation of quantum information theorists and the already established community of classical information theorists.
LSU Physicists Collaborate on T2K CP Violation Results to Explain Workings of Universe: LSU physicists Thomas Kutter and Martin Tzanov were among the international T2K Collaboration who recently announced their findings on the symmetry between neutrino and antineutrino oscillation. With newly collected antineutrino data, T2K has performed a new analysis, fitting both neutrino and antineutrino modes simultaneously. T2K’s new data continue the trends observed in 2015, which is a preference for maximal disappearance of muon neutrinos, as well as a discrepancy between the electron neutrino and electron antineutrino appearance rates. Read more
The LIGO Scientific Collaboration and the Virgo collaboration identify a second gravitational wave event in the data from Advanced LIGO detectors. On December 26, 2015 at 03:38:53 UTC, scientists observed gravitational waves-ripples in the fabric of spacetime-for the second time. The gravitational waves were detected by both of the twin Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. Read more
“CALET Upper Limits on X-Ray and Gamma-Ray Counterparts of GW 151226” has been published by the CALET collaboration including Nick Cannady, Mike Cherry Greg Guzik, Amir Javaid, John Wefel et al. in Astrophysical Journal Letters, 829:L20 (2016). The CALET experiment aboard the International Space Station has placed upper limits for counterpart emission in the 7-1000 keV and 1-100 GeV bands associated with the gravitational wave event GW 151226 corresponding to a luminosity of 3-4 ×1049 erg s−1, which is signiﬁcantly lower than typical short gamma ray bursts. Read more
Extreme light from frozen argon LSU physicists Mette Gaarde, Mengxi Wu, Kenneth Schafer, and Dana Browne, in collaboration with a team of researchers at SLAC/Stanford University have directly compared the ultrafast, extreme ultraviolet radiation emitted by argon atoms when they are in their gas phase or in their weakly bound solid phase and found significant differences between them, as reported today in the journal Nature. The results yield new clues about how energetic electrons in a solid behave, and may yield new compact sources of short wavelength radiation. Read more
"Efficacy of the SU(3) scheme for ab initio large-scale calculations beyond the lightest nuclei" has been published by Tomas Dytrych, Kristina Launey, and Jerry Draayer et. al. Comp. Phys. Commun. 207 (2016) 202; doi: 10.1016/j.cpc.2016.06.006. This paper discuss the computational characteristics of ab initio nuclear structure calculations in the symmetry-adapted no-core shell model (SA-NCSM) framework and examine the computational complexity of the current implementation of the SA-NCSM approach, dubbed LSU3shell, by analyzing ab initio results for Li-6 and C-12 in large harmonic-oscillator model spaces and symmetry-selected subspaces. We demonstrate LSU3shell's strong-scaling properties achieved with highly-parallel methods for computing the many-body matrix elements. In particular, a well-chosen symmetry-adapted basis affords memory savings in calculations of states with a fixed total angular momentum in large model spaces while exactly preserving translational invariance.
"Quantum self-gravitating collapsing matter in a quantum geometry". has been published by Campiglia, Gambini, Olmedo, and Pulin. Classical and Quantum Gravity, Volume 33, Number 18. The problem of how space–time responds to gravitating quantum matter in full quantum gravity has been one of the main questions that any program of quantization of gravity should address. Here we analyze this issue by considering the quantization of a collapsing null shell coupled to spherically symmetric loop quantum gravity. We show that the constraint algebra of canonical gravity is Abelian both classically and when quantized using loop quantum gravity techniques. The Hamiltonian constraint is well defined and suitable Dirac observables characterizing the problem were identified at the quantum level. We can write the metric as a parameterized Dirac observable at the quantum level and study the physics of the collapsing shell and black hole formation. We show how the singularity inside the black hole is eliminated by loop quantum gravity and how the shell can traverse it. The construction is compatible with a scenario in which the shell tunnels into a baby universe inside the black hole or one in which it could emerge through a white hole.
"Ultrathin two-dimensional superconductivity with strong spin–orbit coupling" has been published by Nam, Kim and Adams, et. al. doi:10.1073/pnas.1611967113. September, 2016. We report on a study of epitaxially grown ultrathin Pb films that are only a few atoms thick and have parallel critical magnetic fields much higher than the expected limit set by the interaction of electron spins with a magnetic field, that is, the Clogston–Chandrasekhar limit. The epitaxial thin films are classified as dirty-limit superconductors because their mean-free paths, which are limited by surface scattering, are smaller than their superconducting coherence lengths. The uniformity of superconductivity in these thin films is established by comparing scanning tunneling spectroscopy, scanning superconducting quantum interference device (SQUID) magnetometry, double-coil mutual inductance, and magneto-transport, data that provide average superfluid rigidity on length scales covering the range from microscopic to macroscopic. We argue that the survival of superconductivity at Zeeman energies much larger than the superconducting gap can be understood only as the consequence of strong spin–orbit coupling that, together with substrate-induced inversion-symmetry breaking, produces spin splitting in the normal-state energy bands that is much larger than the superconductor’s energy gap.
"Schrödinger-like quantum dynamics in loop quantized black holes" has been published by Gambini, Rodolfo, Javier Olmedo, and Jorge Pullin. • Int.J.Mod.Phys. D25 (2016) no.08, 1642006 arXiv:1605.00969. This paper show, following a previous quantization of a vacuum spherically symmetric spacetime carried out in [R. Gambini, J. Olmedo and J. Pullin, Class. Quantum Grav. 31 (2014) 095009.] that this setting admits a Schrödinger-like picture. More precisely, the technique adopted there for the definition of parametrized Dirac observables (that codify local information of the quantum theory) can be extended in order to accommodate different pictures. In this new picture, the quantum states are parametrized in terms of suitable gauge parameters and the observables constructed out of the kinematical ones on this space of parametrized states.
Rob Hynes, Brad Schaefer, undergrad Zach Baum, Ching-Cheng Hsu, Mike Cherry et al. present a multi-wavelength study of the low-mass X-ray binary Sco X-1 in "Kepler
K2 Observations of Sco X-1: Orbital Modulations and Correlations with Fermi GBM and
MAXI" in Monthly Notices of the Royal Astronomical Society. Read more
The research of LSU Physicist James Matthews and an international team of scientists is featured in the CERN Courier. The world's largest cosmic-ray experiment, the Pierre Auger Observatory in Mendoza Province, Argentina, is embarking on its next phase, named AugerPrime. Read more
The paper "Angular momentumprojection for a Nilsson mean-field plus pairing model", Nucl. Phys. A 950 (2016) 1; doi:10.1016/j. nuclphysa. 2016.03.012. by Yin Wang, Feng Pan, Kristina D. Launey, Yan-An Luo, and J. P. Draayer, explores the interplay of pairing and deformation in intermediate-mass nuclei based on a new method for restoring the rotational invariance of a general nuclear pairing-plus-deformation Hamiltonian. Read more
Gravitational Waves Detected 100 Years After Einstein's Prediction: For the first time, scientists have observed ripples in the fabric of spacetime, called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein's 1915 general theory of relativity and opens an unprecedented new window onto the cosmos.