Physics Commons^™

Conventions, Definitions, Identities, And Other Useful Formulae, Robert A. Mcnees Iv

Physics: Faculty Publications and Other Works

As the name suggests, these notes contain a summary of important conventions, definitions, identities, and various formulas that I often refer to. They may prove useful for researchers working in General Relativity, Supergravity, String Theory, Cosmology, and related areas.

Neutrino Self-Interactions: A White Paper, Jeffrey M. Berryman, Nikita Blinov, Vedran Brdar, Thejs Brinckmann, Mauricio Bustamante, Francis-Yan Cyr-Racine, Anirban Das, André De Gouvêa, Peter B. Denton, P.S. Bhupal Dev, Bhaskar Dutta, Ivan Esteban, Damiano Fiorillo, Martina Gerbino, Subhajit Ghosh, Tathagata Ghosh, Evan Grohs, Tao Han, Steen Hannestad, Matheus Hostert, Patrick Huber, Jeffrey Hyde, Kevin J. Kelly, Felix Kling, Zhen Liu, Massimiliano Lattanzi, Marilena Loverde, Sujata Pandey, Ninetta Saviano, Manibrata Sen, Ian M. Shoemaker, Walter Tangarife, Yongchao Zhang, Yue Zhang

Physics: Faculty Publications and Other Works

Neutrinos are the Standard Model (SM) particles which we understand the least, often due to how weakly they interact with the other SM particles. Beyond this, very little is known about interactions among the neutrinos, i.e., their self-interactions. The SM predicts neutrino self-interactions at a level beyond any current experimental capabilities, leaving open the possibility for beyond-the-SM interactions across many energy scales. In this white paper, we review the current knowledge of neutrino self-interactions from a vast array of probes, from cosmology, to astrophysics, to the laboratory. We also discuss theoretical motivations for such self-interactions, including neutrino masses and possible …

Fermion Pair Radiation From Accelerating Classical Systems, Margarita Gavrilova, Mitrajyoti Ghosh, Yuval Grossman, Walter Tangarife, Tien-Hsueh Tsai

Physics: Faculty Publications and Other Works

Accelerating classical systems that couple to a fermion-antifermion pair at the microscopic level can radiate pairs of fermions and lose energy in the process. In this work, we derive the generalization of the Larmor formula for fermion pair radiation. We focus on the case of a point-like classical source in an elliptical orbit that emits fermions through vector and scalar mediators. Ultra-light fermion emission from such systems becomes relevant when the mass of the mediator is larger than the frequency of the periodic motion. This enables us to probe regions of the parameter space that are inaccessible in on-shell bosonic …

Finite Charges From The Bulk Action, Robert Mcnees, Céline Zwikel

Physics: Faculty Publications and Other Works

Constructing charges in the covariant phase space formalism often leads to formally divergent expressions, even when the fields satisfy physically acceptable fall-off conditions. These expressions can be rendered finite by corner ambiguities in the definition of the presymplectic potential, which in some cases may be motivated by arguments involving boundary Lagrangians. We show that the necessary corner terms are already present in the variation of the bulk action and can be extracted in a straightforward way. Once these corner terms are included in the presymplectic potential, charges derived from an associated codimension-2 form are automatically finite. We illustrate the procedure …

Neutrino Forces In Neutrino Backgrounds, Mitrajyoti Ghosh, Yuval Grossman, Walter Tangarife, Xun-Jie Xu, Bingrong Yu

Physics: Faculty Publications and Other Works

The Standard Model predicts a long-range force, proportional to G² F /r⁵, between fermions due to the exchange of a pair of neutrinos. This quantum force is feeble and has not been observed yet. In this paper, we compute this force in the presence of neutrino backgrounds, both for isotropic and directional background neutrinos. We find that for the case of directional background the force can have a 1/r dependence and it can be significantly enhanced compared to the vacuum case. In particular, background effects caused by reactor, solar, and supernova neutrinos enhance the force by many …

Ds2 As Excitation Of Ads2, Florian Ecker, Daniel Grumiller, Robert Mcnees

Physics: Faculty Publications and Other Works

Title- dS₂ as excitation of AdS₂

We introduce a family of 2D dilaton gravity models with state-dependent constant curvature so that dS₂ emerges as an excitation of AdS₂. Curiously, the strong coupling region corresponds to the asymptotic region geometrically. Apart from these key differences, many features resemble the Almheiri–Polchinski model. We discuss perturbative and non-perturbative thermodynamical stability, bubble nucleation through matter shockwaves, and semiclassical backreaction effects. In some of these models, we find that low temperatures are dominated by AdS₂ but high temperatures are dominated by dS₂, concurrent with a recent proposal …

Core-Collapse Supernova Constraint On The Origin Of Sterile Neutrino Dark Matter Via Neutrino Self-Interactions, Yu-Ming Chen, Manibrata Sen, Walter Tangarife, Douglas Tuckler, Yue Zhang

Physics: Faculty Publications and Other Works

Novel neutrino self-interaction can open up viable parameter space for the relic abundance of sterile-neutrino dark matter (SvDM). In this work, we constrain the relic target using core-collapse supernova which features the same fundamental process and a similar environment to the early universe era when SvDM is dominantly produced. We present a detailed calculation of the effects of a massive scalar mediated neutrino self-interaction on the supernova cooling rate, including the derivation of the thermal potential in the presence of non-zero chemical potentials from plasma species. Our results demonstrate that the supernova cooling argument can cover …

Dirac Dark Matter, Neutrino Masses, And Dark Baryogenesis, Diego Restrepo, Andrès Rivera, Walter Tangarife

Physics: Faculty Publications and Other Works

We present a gauged baryon number model as an example of models where all new fermions required to cancel out the anomalies help to solve phenomenological problems of the standard model (SM). Dark fermion doublets, along with the isosinglet charged fermions, in conjunction with a set of SM-singlet fermions, participate in the generation of small neutrino masses through the Dirac-dark Zee mechanism. The other SM-singlets explain the dark matter in the Universe, while their coupling to an inert singlet scalar is the source of the CP violation. In the presence of a strong first-order electroweak phase transition, this “dark” CP …

Experimental Radial Profiles Of Early Time (<4 Μs) Neutral And Ion Spectroscopic Signatures In Lightning-Like Discharges, M. Passas-Varo, F. J. Gordillo-Vazquez, J. Sanchez, Ny Kieu Phd

Physics: Faculty Publications and Other Works

This study presents experimental results for the radial and temporal variation of neutral and ion spectroscopic signatures emerging from the heated channel of lightning-like discharges diagnosed with a high speed (900,000 fps) imaging spectrograph. Light emissions emanate from three regions: an inner core (up to ∼2 mm), an external sheath (up to ∼4 mm) featuring a sudden temperature increase, and further optical emissions forming a dim glow from 4 mm up to 16 mm. The optical emissions are initially (

Bridging The 12-6-4 Model And The Fluctuating Charge Model, Pengfei Li

Chemistry: Faculty Publications and Other Works

Metal ions play important roles in various biological systems. Molecular dynamics (MD) using classical force field has become a popular research tool to study biological systems at the atomic level. However, meaningful MD simulations require reliable models and parameters. Previously we showed that the 12-6 Lennard-Jones nonbonded model for ions could not reproduce the experimental hydration free energy (HFE) and ion-oxygen distance (IOD) values simultaneously when ion has a charge of +2 or higher. We discussed that this deficiency arises from the overlook of the ion-induced dipole interaction in the 12-6 model, and this term is proportional to 1/r …

Somatic Inhibition By Microscopic Magnetic Stimulation, Hui Ye

Biology: Faculty Publications and Other Works

Electric currents can produce quick, reversible control of neural activity. Externally applied electric currents have been used in inhibiting certain ganglion cells in clinical practices. Via electromagnetic induction, a miniature-sized magnetic coil could provide focal stimulation to the ganglion neurons. Here we report that high-frequency stimulation with the miniature coil could reversibly block ganglion cell activity in marine mollusk Aplysia californica, regardless the firing frequency of the neurons, or concentration of potassium ions around the ganglion neurons. Presence of the ganglion sheath has minimal impact on the inhibitory effects of the coil. The inhibitory effect was local to the …

Universal Flow Equations And Chaos Bound Saturation In 2d Dilaton Gravity, D. Grumiller, Robert Mcnees

Physics: Faculty Publications and Other Works

We show that several features of the Jackiw-Teitelboim model are in fact universal properties of two-dimensional Maxwell-dilaton gravity theories with a broad class of asymptotics. These theories satisfy a flow equation with the structure of a dimensionally reduced T ¯ T deformation, and exhibit chaotic behavior signaled by a maximal Lyapunov exponent. One consequence of our results is a no-go theorem for smooth flows from an asymptotically AdS₂ region to a de Sitter fixed point.

Exactness Of Swkb For Shape Invariant Potentials, Asim Gangopadhyaya, Jeffry V. Mallow, Emeritus, Constantin Rasinariu, Jonathan Bougie

Physics: Faculty Publications and Other Works

The supersymmetry-based semiclassical method (SWKB) is known to produce exact spectra for conventional shape invariant potentials. In this paper we prove that this exactness follows from their additive shape invariance.

A First-Year Research Experience: The Freshman Project In Physics At Loyola University Chicago, Jonathan Bougie, Asim Gangopadhyaya, Sherita Moses, Robert Polak, Gordon Ramsey, Weronika Walkosz

Physics: Faculty Publications and Other Works

Undergraduate research has become an essential mode of engaging and retaining students in physics. At Loyola University Chicago, first-year physics students have been participating in the Freshman Projects program for over twenty years, which has coincided with a period of significant growth for our department. In this paper, we describe how the Freshman Projects program has played an important role in advancing undergraduate research at Loyola and the profound impact it has made on our program. We conclude with suggestions for adoption of similar programs at other institutions.

Evidence For A Supergalactic Structure Of Magnetic Deflection Multiplets Of Ultra-High-Energy Cosmic Rays, Rasha U. Abbasi

Physics: Faculty Publications and Other Works

Evidence for a large-scale supergalactic cosmic-ray multiplet (arrival directions correlated with energy) structure is reported for ultra-high-energy cosmic-ray (UHECR) energies above 1019 eV using 7 years of data from the Telescope Array (TA) surface detector and updated to 10 years. Previous energy–position correlation studies have made assumptions regarding magnetic field shapes and strength, and UHECR composition. Here the assumption tested is that, because the supergalactic plane is a fit to the average matter density of the local large-scale structure, UHECR sources and intervening extragalactic magnetic fields are correlated with this plane. This supergalactic deflection hypothesis is tested by the entire …

The American Astronomical Society, Find Out More The Institute Of Physics, Find Out More Search For Large-Scale Anisotropy On Arrival Directions Of Ultra-High-Energy Cosmic Rays Observed With The Telescope Array Experiment, Rasha U. Abbasi

Physics: Faculty Publications and Other Works

Motivated by the detection of a significant dipole structure in the arrival directions of ultra-high-energy cosmic rays above 8 EeV reported by the Pierre Auger Observatory (Auger), we search for a large-scale anisotropy using data collected with the surface detector array of the Telescope Array Experiment (TA). With 11 yr of TA data, a dipole structure in a projection of the R.A. is fitted with an amplitude of 3.3% ± 1.9% and a phase of 131° ± 33°. The corresponding 99% confidence-level upper limit on the amplitude is 7.3%. At the current level of statistics, the fitted result is compatible …

Origin Of Sterile Neutrino Dark Matter Via Secret Neutrino Interactions With Vector Bosons, Kevin J. Kelly, Manibrata Sen, Walter Tangarife, Yue Zhang

Physics: Faculty Publications and Other Works

Secret neutrino interactions can play an essential role in the origin of dark matter. We present an anatomy of production mechanisms for sterile neutrino dark matter, a keV-scale gauge-singlet fermion that mixes with active neutrinos, in the presence of a new vector boson mediating secret interactions among active neutrinos. We identify three regimes of the vector boson’s mass and coupling where it makes a distinct impact on dark matter production through the dispersion relations and/or scattering rates. We also analyze models with gauged Lμ−Lτ and B−L numbers which have a similar dark matter cosmology but different vector boson phenomenology. We …

Probing The Two-Neutrino Exchange Force Using Atomic Parity Violation, Mitrajyoti Ghosh, Yuval Grossman, Walter Tangarife

Physics: Faculty Publications and Other Works

The exchange of two neutrinos at one loop leads to a long-range parity-violating force between fermions. We explore the two-neutrino force in the backdrop of atomic physics. We point out that this is the largest parity-violating long-range force in the Standard Model and calculate the effect of this force in experiments that probe atomic parity violation by measuring optical rotation of light as it passes through a sample of vaporized atoms. We perform explicit calculations for the hydrogen atom to demonstrate this effect. Although we find that the effect is too small to be observed in hydrogen in the foreseeable …

Inter-Relations Between Additive Shape Invariant Superpotentials, Jeffry V. Mallow, Emeritus, Asim Gangopadhyaya, Jonathan Bougie, Constantin Rasinariu

Physics: Faculty Publications and Other Works

All known additive shape invariant superpotentials in nonrelativistic quantum mechanics belong to one of two categories: superpotentials that do not explicitly depend on ħ, and their ħ-dependent extensions. The former group themselves into two disjoint classes, depending on whether the corresponding Schrödinger equation can be reduced to a hypergeometric equation (type-I) or a confluent hypergeometric equation (type-II). All the superpotentials within each class are connected via point canonical transformations. Previous work [19] showed that type-I superpotentials produce type-II via limiting procedures. In this paper we develop a method to generate a type I superpotential from type II, thus …

Dodelson-Widrow Mechanism In The Presence Of Self-Interacting Neutrinos, André De Gouvêa, Manibrata Sen, Walter Tangarife, Yue Zhang

Physics: Faculty Publications and Other Works

keV-scale gauge-singlet fermions, when allowed to mix with the active neutrinos, are elegant dark matter (DM) candidates. They are produced in the early Universe via the Dodelson-Widrow mechanism and can be detected as they decay very slowly, emitting x-rays. In the absence of new physics, this hypothesis is virtually ruled out by astrophysical observations. Here, we show that new interactions among the active neutrinos allow these sterile neutrinos to make up all the DM while safely evading all current experimental bounds. The existence of these new neutrino interactions may manifest itself in next-generation experiments, including DUNE.

Singlet-Doublet Dirac Dark Matter And Neutrino Masses, Diego Restrepo, Andrés Rivera, Walter Tangarife

Physics: Faculty Publications and Other Works

We examine an extension of the Standard Model that addresses the dark matter puzzle and generates Dirac neutrino masses through the radiative seesaw mechanism. The new field content includes a scalar field that plays an important role in setting the relic abundance of dark matter. We analyze the phenomenology in the light of direct, indirect, and collider searches of dark matter. In this framework, the dark matter candidate is a Dirac particle that is a mixture of new singlet-doublet fields with mass mχ01≲1.1  TeV. We find that the allowed parameter space of this model is broader than the well-known Majorana …

Bounds On Extra Dimensions From Micro Black Holes In The Context Of The Metastable Higgs Vacuum, Katherine J. Mack, Robert A. Mcnees Iv

Physics: Faculty Publications and Other Works

We estimate the rate at which collisions between ultrahigh-energy cosmic rays can form small black holes in models with extra dimensions. If recent conjectures about false vacuum decay catalyzed by black hole evaporation apply, the lack of vacuum decay events in our past light cone may place new bounds on the black hole formation rate and thus on the fundamental scale of gravity in these models. For theories with fundamental scale E∗ above the Higgs instability scale of the Standard Model, we find a lower bound on E∗ that is within about an order of magnitude of the energy where …

Detection Of Mg2+-Dependent, Coaxial Stacking Rearrangements In A Bulged Three-Way Dna Junction By Single-Molecule Fret, Michael P. Leveille, Thao Tran, Gianna Dingillo, Brian Cannon

Physics: Faculty Publications and Other Works

Three-way helical junctions (3WJs) arise in genetic processing, and they have architectural and functional roles in structured nucleic acids. An internal bulge at the junction core allows the helical domains to become oriented into two possible, coaxially stacked conformers. Here, the helical stacking arrangements for a series of bulged, DNA 3WJs were examined using ensemble fluorescence resonance energy transfer (FRET) and single-molecule FRET (smFRET) approaches. The 3WJs varied according to the GC content and sequence of the junction core as well as the pyrimidine content of the internal bulge. Mg2+ titration experiments by ensemble FRET show that both …

Conservation Laws And Energy Transformations In A Class Of Common Physics Problems, Jonathan Bougie, Asim Gangopadhyaya

Physics: Faculty Publications and Other Works

We analyze a category of problems that is of interest in many physical situations, including those encountered in introductory physics classes: systems with two well-delineated parts that exchange energy, eventually reaching a shared equilibrium with a loss of mechanical or electrical energy. Such systems can be constrained by a constant of the system (e.g., mass, charge, momentum, or angular momentum) that uniquely determines the mechanical or electrical energy of the equilibrium state, regardless of the dissipation mechanism. A representative example would be a perfectly inelastic collision between two objects in one dimension, for which momentum conservation requires that some of …

Mario Kart 8: A Case Study In Total Internal Reflection, Robert Polak, Vincent Acuesta, Jonathon Cirone, Matthew B. Conway, Joseph Summers, Lana Tinawi

Physics: Faculty Publications and Other Works

No abstract provided.

Building Confidence In The Dirac Δ-Function, Asim Gangopadhyaya, Constantin Rasinariu

Physics: Faculty Publications and Other Works

In this note we present an example from undergraduate quantum mechanics designed to highlight the versatility of the Dirac δ-function. Namely, we compute the expectation value of the Hamiltonian of a free particle in a state described by a triangular wave function ψ(x). Since the first derivative of ψ(x) is piecewise constant, and because this Hamiltonian is proportional to the second order spatial derivative, students often end up finding the expectation value to be zero—an unphysical answer. This problem provides a pedagogical application of the Dirac δ-function. By arriving at the same result via alternate pathways, this exercise reinforces students’ …

The Supersymmetric Wkb Formalism Is Not Exact For All Additive Shape Invariant Potentials, Jonathan Bougie, Asim Gangopadhyaya, Constantin Rasinariu

Physics: Faculty Publications and Other Works

Following the verification of the conjecture made by Comtet et al that the supersymmetry-inspired semiclassical method known as SWKB is exact for the conventional additive shape invariant potentials, it was widely believed that SWKB yields exact results for all additive shape invariant potentials. In this paper we present a concrete example of an additive shape invariant potential for which the SWKB method fails to produce exact results.

Menagerie Of Ads2 Boundary Conditions, Daniel Grumiller, Robert A. Mcnees Iv, Jakob Salzer, Carlos Valcárcel, Dmitri Vassilevich

Physics: Faculty Publications and Other Works

We consider different sets of AdS2 boundary conditions for the Jackiw-Teitelboim model in the linear dilaton sector where the dilaton is allowed to fluctuate to leading order at the boundary of the Poincaré disk. The most general set of boundary conditions is easily motivated in the gauge theoretic formulation as a Poisson sigma model and has an sl(2)" role="presentation" style="box-sizing: inherit; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">𝔰𝔩(2)sl(2) current algebra as asymptotic symmetries. Consistency of the …

Galileo's Contribution To Mechanics, Asim Gangopadhyaya

Physics: Faculty Publications and Other Works

Asim Gangopadhyaya writes about Galileo's contributions to mechanics and physics in this chapter in Where Have All the Heavens Gone? Galileo's Letter to the Grand Duchess Christina edited by John P. McCarthy and Edmondo F. Lupieri.

Can Newton’S Third Law Be “Derived” From The Second?, Asim Gangopadhyaya, James T. Harrington

Physics: Faculty Publications and Other Works

Newton’s laws1 have engendered much discussion over several centuries.2,3 Today, the internet is awash with a plethora of information on this topic. We find many references to Newton’s laws, often discussions of various types of misunderstandings and ways to explain them. Here we present an intriguing example that shows an assumption hidden in Newton’s third law that is often overlooked. As is well known, the first law defines an inertial frame of reference and the second law determines the acceleration of a particle in such a frame due to an external force. The third law describes forces exerted …