SSPAR is a series of talks given by students to other students. It allows graduate students to practice public speaking and giving research seminars. Our seminars are at 7pm on Thursdays in Serin 112W, so please come check us out! We have pizza and drinks provided, courtesy of the GSA.
Previous seminars are stored here, where you can see the speaker, title, and abstract for each talk.
Moonshine: The Monster under your theory
The 1998 Fields Medal was awarded to Richard Borcherds for his proof of what is known as the Moonshine conjecture. With this proof came the introduction of structures known as vertex operator algebras which have been extremely fruitful in string theory. This has also opened the doorway to a large series of mysterious and deep connections between number theory, finite group theory, and conformal field theory. In this talk we will take a brisk walk through many of the exciting features of Moonshine, particularly Monstruous Moonshine, keeping a close eye to the physical motivation.
Strain Engineering in 2D materials
Generating Strain in any crystal causes its electro-optic properties to change. 2D crystalline materials like Graphene, hexagonal Boron Nitride and MoS2 can survive significantly higher strains than 3D materials owing to their high mechanical strength. This enables us to engineer the electro-optic properties of these 2D materials simply by generating strain in them. Moreover, many of these 2D materials have been predicted to show a very strong Piezoelectric effect. This is particularly exciting because of the potential applications in self-powered electronic devices and sensors.
Sampling the Initial Mass Function for Cosmological Simulations
Cosmological simulations seek to recreate the process of galaxy formation and evolution as accurately as possible. As resolutions get higher, it becomes necessary to implement a more realistic prescription for star formation. With this motivation, I discuss the initial mass function, which describes the mass distribution of stars at the time of formation. I will consider proper sampling methods for this function, and prospects for implementing them into cosmological simulations. Pretty pictures of space guaranteed.
Lattice systems and the Thirring Model
In this talk we will be having fun with 1 dimensional quantum systems, including the famous Heisenberg XXZ spin chain. We will see how the scaling limit of the spin chain results in the Thirring Model, a Quantum Field Theory of Dirac fermions . Along the way, we’ll touch on a number of key physics ideas such as Universality and Lorentz Invariance.
The Ricci Flow
The Ricci flow is a natural generalization of the heat equation to the geometry of manifolds. It is fundamentally related to the renormalizability of certain field theories called nonlinear sigma models. In the 1980's, the Ricci flow was studied in differential geometry as a tool to investigate the decomposition of three dimensional manifolds. These studies ultimately led to the proof of the Poincare conjecture. In this talk, we will look at solutions to the Ricci flow in two and three dimensions and what this means for physics.
Maintenance of mental health as a graduate student: addressing a silent epidemic
Mental health problems among the population of graduate students in science will be discussed, with a particular focus on depression and suicidal ideation. The speaker will present on the empirical prevalence of such issues, in combination with an overview of resources available local to Rutgers, practices of hygiene, and coping skills.
Raghav Kunnawalkam Elayavalli
Jetting through the primordial soup
Ever since RHIC announced the creation of the quark gluon plasma in relativistic heavy ion collisions, study of the strongly interacting, high temperature and high energy density has elucidated several key features of QCD. We at Rutgers are experts in creating a tomographical picture of the QGP by utilizing fully reconstructed objects called jets, that travel through the medium on its way to our detectors. In this talk, I will attempt to draw a state of the art qualitative (and quantitative to a degree) picture of what happens to a parton moving through this dense (colored) medium and our takeaways from measurements at the LHC.
Dynamics of 1D Bosons in the presence of electric field- You know what I did last summer
We study the exact dynamics of 1D interacting Bose gas in the presence of a spatially uniform, time dependent Electric field. We begin by introducing and exactly solving the Lieb-Liniger model of 1D Bose gas, in the absence of any electric field and proceed to solve the time dependent Schrodinger's equation in the presence of a time dependent linear potential.
SeaQuest - Studying Sea Quark Asymmetry
I'll be going over the physics of the SeaQuest experiment, the Drell-Yan process, and how we use it to probe the quark distributions of the nucleus. There will also be discussion of general issues in nuclear structure including the EMC effect, the Gottfried Sum Rule, and quark flavor asymmetry.
String Theory: What is it good for?
Despite what Edwin Starr might tell you, string theory is a very useful tool for physicists that has led (and probably will lead) to many new ways of thinking about quantum physics. For example the study of string theory has lead to the discovery of exotic quantum theories without a known Lagrangian description and has lead to the discovery of the AdS/CFT correspondence. In addition, string theory gives us a way to study strongly coupled quantum field theories, which may potentially lead insight into fundamental problems such as quark confinement.
You Would Be Forgiven for Assuming that We Understand the Proton
In 2010 Randolf Pohl measured the radius of the proton to be 4% smaller than the accepted CODATA radius with an unprecedented accuracy. This may not sound significant but the Proton Radius Puzzle is a high profile issue within the nuclear physics community. In this talk the Puzzle will be discussed and the Muon Proton Scattering Experiment’s place in attempting to resolve the Puzzle will be presented.
Introduction to Markov Chain Monte Carlo
Markov chain Monte Carlo is arguably one of the most important algorithms and is extensively used in modern simulations and numerical methods. A brief overview of Markov chains and Monte Carlo will be introduced. More importantly, for modern graduate students not only could Markov chain Monte Carlo be useful, but the advent of pizza is also very important in physics.
Raghav Kunnawalkam Elayavalli
Physics of the Beam. "Scotty, beam us up!"
Beams have always been used by physicists to study many different aspects of nature. From your simple table top diffraction experiment to the largest operating experiment on the planet, we all use some form of either a beam to probe or scatter or annihilate objects. In this talk, I will focus more on the particle beams at CERN and particularly how they produce and maintain said stable beams for physics collisions. This procedure of generating a beam of highly focused particles from a canister of gas contains many different steps, some of which are a phenomenal feat of scientific ingenuity and engineering receiving the highest award for scientific research, the Nobel Prize in 1984. This has also led to remarkable public utility in many fields such as medicine and consumer electronics (on which you are all reading this abstract).
The Wonderful World of One Dimension (Plus Time)
On Exact Solutions of Novel Multistate Landau-Zener Problems
A multistate Landau-Zener (MLZ) Hamiltonian is used to model numerous non-equilibrium experiments involving cold atoms, quantum dots and quantum dot molecules. We recently showed that all the known MLZ problems either reduce to the 2 X 2 Landau Zener problem or belong to a family of mutually commuting Hamiltonians (that are polynomial in time). Based on this classication we identify previously unknown MLZ problems, explicitly obtain their solutions and discuss relevant experimental scenarios.
One of the questions of fundamental physics is understanding the asymmetry between electric and magnetic fields: namely why is there electrically charged matter but no magnetically charged matter. The question of why there are no monopoles have baffled physicists for a very long time. The idea of these "particles" has been revisited at every theoretical revolution in the past century by people such as Dirac, 't Hooft, Polyakov, and many others. In this talk we will talk about the role of monopoles in modern physics and how they relate to cosmology, condensed matter, particle physics, and the role of confinement.
Integral Systems and Quenching
Interacting systems in quantum physics are common place, but only few systems are integrable. In this talk we discuss mostly Lieb-Liniger system, which is integrable exactly using Bethe Anstaz. We will also then talk about quantum quenching a free bosonic system with Leib-Liniger Hamiltonian using the Yudson representation.
Long Yan Yung
The Interplay of Cosmic Reionization and Galaxy Formation
During its 13.8 billion-year-long evolution, our Universe has undergone many phases and phase transitions. Two of the most interesting events in cosmic history are the formation of the first galaxies and cosmic reionization. Galaxies are regarded as the fundamental entities of large-scale structures in the Universe, which their formation strongly dependent on the cosmic environment. On the other hand, these galaxies can also provide feedback effects that can alter the cosmic environment, hence indirectly shape future formation activities. Galaxy formation is inseparable from the evolution of the cosmic environment. Therefore, understanding the interplay of the two can help us better understand the overall cosmic evolution history.
Given its scalability and compatibility to current silicon industry, superconducting qubit has become an ideal candidate for realizing quantum circuits. In order to understand and achieve reliable quantum operation, I would like to focus on the fundamental building blocks of superconducting circuits, which is the Josephson junction. In this talk, I will introduce the properties of Josephson junctions elements, the experimental approaches to fabricate and characterize Josephson junctions, and investigate the possible application of superconducting qubits.
Since their invention in the 17th century microscopes were thought to have enjoyed unlimited improvement, but 1873 Ernst Abbe developed the diffraction limit. Superresolution microscopy are techniques that work around the diffraction limit to improve resolution more than 10 fold with visible light and, in some cases, promise unlimited resolution. Unlike their high resolution, diffraction limited cousins such as X-Ray microscopy, these methods allow for greater range of samples and are paving the way for readily accessible widefield, live imaging.
Gravitational Lensing by Galaxy Clusters
Galaxy clusters are the largest gravitationally bound structures in the Universe. Consisting of thousands of galaxies, hot intra-cluster gas, and dark matter, they are also the most massive structures known. Since they are so dense, they cause light from background sources to be bent around them, a phenomenon known as gravitational lensing. The bending both distorts and magnifies these distant sources, allowing them to be more easily detected and studied, which has earned cluster lenses the name 'cosmic telescopes'. In this talk I will give background information on gravitational lensing and discuss techniques in how we model these complex mass distributions.
What's inside a black hole?
Black holes are mysterious objects which came out of general relativity (GR). They taught us a lot about GR in the past and now they are playing a key role in understanding quantum gravity. They are also being used as tools in understanding highly coupled gauge theories, certain condensed matter systems and the list goes on. But what is inside a black hole is still a mystery. I will give a qualitative explanation of how a black hole curves space-time and then I will briefly go over hawking radiation and the puzzles which come out of it. I will then give a summary of some important papers which try to solve these puzzles thereby revealing a plausible structure of the black hole. In the end I will talk about the current research relating AdS/CFTto black hole interior.
"I'm going to talk about Tin"
I present an overview of a study of the phase and interface properties of pure Sn by molecular dynamics, and describe the application of non-Boltzmann simulation to this end. Several orientations of both alpha- and beta-Sn crystals have been simulated in direct coexistence with liquid at constant pressure, with potentials provided by the Modified Embedded Atom Method (MEAM). Simulations are carried out for pressures ranging from zero to 10 GPa and temperatures from 200 K to 1000 K. A complete phase diagram for Sn is mapped on this interval, and comparison is made between competing sets of MEAM parameters with regard to phase stability.
Gravity from Entanglement
Entanglement Entropy in the recent year has been a powerful tool to provide with new insights in various areas of Physics. One class of such attempts was to provide us insights about gravity in the context of gravity. Inspired by the approach taken by Ted Jacobson in deriving the Einstein's equations starting from Thermodynamical arguments. We are exploring such a possibility starting from the Quantum informatic arguments. We take condition of positivity of relative entropy arising from Unitarity quantum mechanics and imposing these arguments in the context of holography with the help of Ryu-Takayanagi formulation. Imposing these relative entropy conditions on the Quantum Field theories with Holographic dual, we explore constrains imposed on the gravitational theories allowed in the holographic bulk.
Raghav Kunnawalkam Elayavalli
Heavy Ions at the LHC: When protons aren't big enough
Heavy Ion physics has a rich history of studies carried out at Berkeley, SPS, RHIC and now at CERN where nuclear physicists are pushing the boundaries of our understanding of the strong force. At such high energies, heavy ion collisions create a viscus, high temperature and strong force mediated fluid called the quark gluon plasma (QGP). Here are Rutgers, we are involved with the CMS detector and study the transport and topological properties of the QGP. I’ll give a brief introduction to the field, our motivation and what we have learnt so far from the first run followed by an outlook to the future in this experiment driven field.
How to Build a Proton: Quarks, Gluons and Supercomputers
The Standard Model of Particle Physics is an enormously successful theory. It is also an enormously rich and complicated theory. Much of that richness and complexity stems from quantum chromodynamics (QCD), the gauge theory of the strong interaction. QCD describes how quarks interact via gluons to form protons, neutrons and, indeed, most of the visible matter in the Universe. Unfortunately QCD cannot be solved analytically (at least, not yet), because it is inherently nonperturbative and confining. In other words, we can never observe individual quarks, only their bound states, such as protons and neutrons. The only method we have for a rigorous understanding of QCD is lattice QCD, in which we discretise spacetime and study the properties of QCD statistically, usually on supercomputers. I will introduce lattice QCD, discuss some of its successes and challenges and, of course, how to build a proton.
An Introduction to the Standard Model
The Standard Model describes the matter content and interactions of the most fundamental particles of nature. It is one of the most successful theories in the history of physics in both prediction and experimental verification. However, there are many problems with the Standard Model, such as lack of gravity, description of dark matter, and matter/anti-matter asymmetry. In this talk we will describe some of these issues and some of their proposed resolutions.
Random matrix theory: The greatest theory?
In the mid-twentieth century, physicists made the surprising discovery that square arrays of completely random numbers can be useful for characterizing Hamiltonians of real quantum systems. A cornerstone of random matrix theory is the nearest neighbor level spacing distribution: i.e. the histogram of spacings between consecutive eigenvalues. For typical random matrix ensembles and generic quantum systems, eigenvalues exhibit repulsive correlations. For special classes of physical models, however, the eigenvalues lose this repulsion and do not see each other at all. These systems are called integrable and my research has investigated the level statistics of ensembles of integrable matrices. Come see the results!
Super-resolution: A Brief Overview
Super-resolution techniques are a means for us to go beyond the Abbe diffraction limit without the need for potentially harmful elections or high energy photons. These techniques, along with clever experimental methods, have allowed us to better analyze biological specimen without killing them or freezing them, and to overcome issues common and advance microscopy techniques bring to live biological studies. This talk will motivate the need for super-resolution, give an overview of the two types, 'true' and 'functional,' and briefly discuss how compressed sensing - a sparse signal analysis method - and super-resolution work together to allow for analysis of more complex systems.
Introduction to Instantons
Instantons are non-perturbative solutions to the classical equations of motion which have non-trivial topology and are relevant to quantum phenomena. In standard quantum mechanics, they primarily determine tunneling and decay rates. However in quantum field theory, they also contribute to a class of operators which break chiral symmetry and can lead to baryon decay. This talk will give an introduction to these non-perturbative solutions and how they lead to these unexpected quantum effects.
LDA+DMFT implementation on H2 molecule
Dynamical Mean Field Theory (DMFT) is a powerful method to deal with strongly correlated materials where quasi-particle approach used in band structure calculation completely fails. In order to perform a realistic calculation, DMFT is combined with local density approximation (LDA+DMFT) and it is widely used in solids to predict properties of correlated systems. Here one of the simplest strongly correlated systems, the hydrogen molecule H2, is used as a testbed to develop a parameter-free LDA+DMFT framework.
An introduction to galaxy clusters
Galaxy clusters are the most massive virialized structures in the universe. The evolution of cluster galaxies is highly dependent on the physics of their environment. I will give examples of how neutral hydrogen is dissipated in clusters and how such mechanisms can quench star formation.
High Throughput Density Functional Theory Calculations for Predicting New Ferroelectrics
A major goal of materials science is the discovery and design of new functional materials. Historically this process consisted of synthesis and experimental characterization of candidate materials, many of which would then be found to be neither interesting nor useful. First principles techniques allow for the structure and properties of candidate materials to be predicted before synthesis, providing valuable input for experimentalists. In this work first principles methods are used to explore candidate ferroelectrics in the LiGaGe structure type.
Raghav Kunnawalkam Elayavalli
A First look at Heavy Ion Collisions
Relativistic heavy ion collisions were first conceptualized by Fermi and Landau independently as a study of the bulk properties of nuclear matter. This was a tool to explore multi-particle productions/interactions, hadron gas systems, thermalized equilibrium and many such novel concepts. From the early 1-2GeV(Giga electron volt) per nucleon at Berkeley and Dubna to the current 200 GeV/nucleon at RHIC, Brookhaven National Lab and 2.76 TeV (tera electron volt)/nucleon at the LHC, we have uncovered many interesting phenomenon. The formation of strongly coupled medium (often called as the quark gluon plasma) is one of the main discoveries and I will focus my talk on the studying its properties. We will start with a conceptualized study of the theory/intuition behind the formation of such a medium and study some of its properties with experimental probes.
Stealth Super Symmetry at 13 TeV Ideas and Tools
The LHC (Large Hadron Collider) revealed the existence of a Higgs-like particle providing the missing piece of the Standard Model. With the forthcoming restart of the collider at an ever-higher center of mass energy, techniques are being developed to face the new run challenges and to provide insight to what lies beyond the current understanding. Existing tools and ideas for a Stealth Supersymmetry search at the CMS (Compact Muon Solenoid) Experiment, will be presented at this talk, regarding boosted topologies involving photons and jets in the final state.
Scalar Dark Matter from Grand Unified Theories
The Standard Model is one of the greatest achievements in physics of the past 50 years, being touted by many as the most successful theory of nature. It precisely describes many observed phenomena, including both electromagnetism and the interactions of nuclear particles; but it is not complete. One of the largest flaws of the standard model is derived from a collection of cosmological observations which points to the existence of a new type of matter which is not described standard model. While many dark matter candidates have been proposed with varying degrees of success, there is still no single theory of dark matter which has been universally accepted. In this talk, a new dark matter candidate will be proposed originating from the Higgs sector of grand unified theories after symmetry breaking at the grand unification scale.
Modelling strongly correlated electron systems from the DMFT viewpoint
The DMFT (dynamic mean field theory) method, first introduced to study the metal insulator transition (MIT) behind the Hubbard model in infinite spatial dimensions, has been merged with the traditional density function theory (DFT), which is capable of capturing the correlation effect missed by DFT. In this talk, the DMFT method is discussed at some details, followed with a discussion on MIT. Next we introduce a formalism based on effective action to combine DFT and DMFT and use it to study the alpha-gamma transition in elementary cerium.
Heavy Flavor Tagged Jets In Heavy Ion Collisions at CMS
Quark-gluon plasma (QGP) can be produced reliably for study in the laboratory using ultra-relativistic heavy ion collisions. These collisions are achieved by using the Large Hadron Collider (LHC), and then recorded at the Compact Muon Solenoid (CMS) Experiment. Events known as jets are readily observed and used as probes to deduce properties of the QGP medium. Jet shapes and momenta are expected to be altered by the medium, as well as their production cross sections. Using specific tagging algorithms, one can identify the flavor of the parton which started the jet. Thus modifications due to the presence of a hot and dense medium can be parameterized as a function of jet-flavor. In this talk, results at CMS involving heavy flavored jets are summarized and discussed.
What's 3d about 2d CFT?
Conformal field theories are related to models of statistical physics at critical point. These theories are epsecially interesting in two dimensions because the group of local conformal transformations is just given by holomorphic functions. Wess-Zumino-Witten models are a class of CFTs whose solutions are characterised by affine Kac-Moody algebras. There is a close connection between Chern-Simons theory on a 3-manifold with a boundary, and a Wess-Zumino-Witten conformal field theory on that boundary. This connection is made explicit by identifying a basis of the Hilbert space of the CS theory with the set of characters of the corresponding WZW theory. I attempt to make this correspondence more explicit, and provide illustrative examples.
Reducing Ambiguities in Spectroscopic Factors and the 86Kr(d,p) reaction at 35MeV/u
We can experimentally probe nuclear structure with single nucleon transfer reactions, such as (d,p), and characterize its shape with parameters like the spectroscopic factor and asymptotic normalization coefficients (ANC). Determining spectroscopic information for neutron rich nuclei near the N=50 shell closure is important in both astrophysics and nuclear physics for understanding r-process solar abundances and nuclear structure far from stability. Mukhamedzhanov and Nunes have proposed a new method of measuring a single particle transfer reaction at both low (peripheral reaction) and higher (less-peripheral) energies that should enable spectroscopic factors to be more reliably deduced, with uncertainties dominated by the experimental cross-section measurement rather than the shape of the single-particle nucleon-target interaction.
Bose-Einstein Condensates, Optical Lattices, and Integrability
Using gases of ultra cold atoms and counter propagating lasers it is possible to directly realise many theoretical models developed in the context of solid state physics. The amount of control and precision afforded by these experiments puts new emphasis on theoretical descriptions that can be solved exactly. In this talk I will describe these experiments, what an exactly solvable model is and one way to exactly solve an exactly solvable model.
Scaling Theory & Network Diffusion in Biological Systems
Transport on networks is an important function for various biological systems. Having a full theory of transport would be highly valuable, but this task has proven to be a challenge. One method that was introduced by Gallos et al to help develop these ideas further was the concept that renormalization can be applied to bionetworks.
Understanding Spectral Energy Distributions and the Physics Behind Them
Astronomers love showing plots of any kind. One, called the spectral energy distribution (SED), is particularly useful for characterizing the radiative processes in astrophysical systems. I will present the SED of a prototypical star forming galaxy and explain the wide range of physics that give rise to its features.