### 2023 Leinweber Fellows

**Postdoctoral Fellows**

In 2023, I will graduate from UCLA and join UM as a Leinweber and Van Loo Postdoctoral Fellow, working with Professor Henriette Elvang in the Leinweber Center for Theoretical Physics. My research spans several areas of theoretical high-energy physics centered around scattering amplitudes and modular symmetry. Scattering amplitudes are fundamental objects in theoretical physics which can be measured in experiments and reveal deep connections between physics and pure mathematics. At UM, I plan to study several active sub-fields within the field of scattering amplitudes, including effective field theories, the double-copy, and the S-matrix bootstrap.

Outside of research, I work with a variety of organizations to support under-represented minority groups in STEM fields. I am Mexican-American and a first-generation college student, and I owe much of my success to my own mentors. I intend to continue my mentorship and outreach work at UM.

**Graduate Students, Summer Fellowships**

Evan grew up in western Massachusetts, completed his undergraduate degree at Johns Hopkins, and is currently a second year PhD student working with Professor Aaron Pierce. Evan is broadly interested in Beyond the Standard Model (BSM) phenomenology and early universe cosmology.

Evan’s current research project is in the realm of precision electroweak analysis. He is using precision collider measurements to place bounds on models of new physics and exploring how these models could help to alleviate existing tensions in data.

Evan is super excited to continue his work this summer, and would like to extend his gratitude to the Leinweber family for their generous support.

Ismael Mendoza was born and raised in Monterrey, Mexico. He is a fourth year graduatestudent in the University of Michigan pursuing a PhD in Physics and Scientific Computing. Herecently completed a MS in Computer Science at Stanford University, where he also received aBS in Physics with Honors.

Ismael has conducted research in optimization theory, general relativity, and computationalbiology, but his main interest is observational cosmology. He focuses on building algorithms toaccurately measure visually overlapping galaxies from the Rubin Observatory Legacy Survey ofSpace and Time (LSST), the most sophisticated optical ground-based astronomical survey todate. Ismael also works on analyzing large volumes of data from dark matter simulations tobetter understand galaxy cluster observables.

Outside of research, he is passionate about teaching and education equity. Ismael has designedand taught several physics and programming courses. He has also worked with children andadults in low-income neighboring communities as a volunteer tutor.

Finally, Ismael is an active member of several scientific communities such as the LSST DarkEnergy Science Collaboration, and a member of the Physics Graduate Council at UofM.

I'm a second year student working for Professor Henriette Elvang, studying scattering amplitudes. I got my undergraduate degree in Physics and Mathematics at Williams College. The focus of my research is finding S-matrix bootstrap bounds on effective field theories, trying to learn how fundamental physical assumptions constrain the physics we observe at low energies. Currently, I am interested in understanding how these bounds can be applied in phenomenological contexts and potentially be applied to experimental observations of effective field theory coefficients.

I’m very happy to be here at Michigan following my undergraduate education at Illinois. Professor Fred Adams is advising me on characterizing solutions to Hill’s equations with various types of time-dependent perturbations. This broadly applicable math problem can describe quantum systems on a lattice, astrophysical orbits of any scale, and post-inflationary reheating, to name a modest few. My background in cosmology gave me special interest in the latter scenario, where I’d like to model reheating with the Universe’s expansion as a perturbative effect. Reheating is the gate between our Standard Model and the birth of the Universe, giving us a window to constrain hypotheses about new physics like the dark sector and quantum gravity. I’m grateful to the Leinweber family for the privilege of learning from the amazing people here at the LCTP every day.Besides this research, I am working on earning a Graduate Teaching Certificate, and I have already had so much fun developing course materials and watching students grow. I enjoy creativity through painting and ceramics, as well as my delicious new sourdough hobby.

I grew up in the outskirts of Kozhikode, a city in the south Indian state of Kerala. It ismy parents who first ignited a passion for science in me by introducing me to this weeklychildren’s science magazine called ‘Eureka’. I soon became friends with this book, whichinvited me to the exciting world of science, math, and history.When I was in class five, my parents took me to the Regional Science centre andPlanetarium in Kozhikode. I was fascinated by that experience, which later became a placeI often visited. The science outreach programs conducted by the University of Calicut alsoencouraged my curiosity. Later, while doing my undergraduate at IISER, I came across‘Disha’, a program promoting basic science among school children. I consider it as apersonal commitment to volunteer and create opportunities for children, like those I gotas a kid.While in school, I was good at my studies but was extremely shy. Fortunately, I had agroup of friends who somehow balanced my quiet nature by including me in their activecompany. After my class 12 board exams, I got into my dream college, the Indian Instituteof Science Education and Research (IISER) at Pune. Going to IISER, far from my home,was not easy for a shy and silent boy like me. The inclusive community of IISER helpedme overcome these weaknesses. I deeply admire the bond I developed and the support Igot from this diverse group of peers from different cultures across India.My interaction with those like-minded people at IISER slowly gravitated me towardshigh energy physics. This motivated me to come to the University of Michigan for mygraduate studies. Although moving to a different country half way across the globe waschallenging, the peers, faculty and the people of UMich eased this transition. The weeklyjournal clubs and seminars in the further encouraged me to continue in HeP.Besides academics, I am passionate about pencil drawing. As an artist, I have thisinstinct of capturing the snapshots of reality with my pencils and a persistent endeavour tobetter my work. Often, when it comes to research, I feel that a reflection of this characteris driving my curiosity.

I'm a fourth-year graduate student working with Jim Liu to understand precision holography. In particular, the AdS/CFT correspondence gives a non-trivial correspondence between gravity in d-dimensions and a non-gravitational theory in (d-1)-dimensions. This correspondence takes place in a particular limit where the string length is taken to zero, and I work on refining this correspondence by looking at higher-derivative corrections which correspond to an expansion in small but finite string length. I am currently looking at what happens when you try to curl up extra dimensions in the presence of these corrections, as well as what implications there are for renormalization group flows.

I got a bachelor's degree at MIT with a double major in physics and mathematics. There I worked on several projects: ranging from projects outside physics that dealt with other quantitative areas at MIT's Computational Psycholinguistics Lab and its Election Data Science Lab, to physics projects that dealt with simulation of neutron scattering and lattice QCD.

As a graduate student in the physics PhD program here at the University of Michigan, I am working in the Leinweber Center for Theoretical Physics on high-energy theory. Currently, I am studying entanglement entropy as how it relates to UV-IR mixing with Professor Ratindranath Akhoury.

Emery Trott is a graduate student working with Professor Dragan Huterer. His work focuses on techniques for combining dark siren gravitational wave events with galaxy surveys to measure the Hubble constant. This work can provide an independent perspective on the outstanding Hubble tension, which may point to new physics beyond the standard LCDM cosmological model.

I am a Ph.D. candidate in Department of Physics, University of Michigan, currently doing research on black holes in string theory and quantum field theories under supervision of Prof. Finn Larsen. Before coming to Michigan, I graduated from Seoul National University in 2019 where I was awarded the Presidential Science Scholarship.

My research focuses on the entropy of black holes. Among the most fascinating scientific discoveries in the last few decades is the fact that black holes have thermal and statistical entropy, and it continues to be a very active and ongoing subject in theoretical physics. I delve into a class of black holes that respect supersymmetry, which allows us to construct a string theoretical model that describes the black hole in detail. Based on recent discoveries that found the agreement between the black hole entropy and its number of microstates, I aim to bolster the relation by understanding what the microstates are and how they work together to form a massive object. For example, it is to be seen if black hole can be constructed using massive, bulky objects in string theory called D-branes, and strings attaching to them. I am also working on writing down local operators in quantum field theories that correspond to quantum states of the smallest black holes.

I’m a second-year student working with Leopoldo Pando Zayas. Originally from western PA, I completed my undergrad work at UC Berkeley before coming here to Michigan. Broadly speaking, my research is centered on the AdS/CFT correspondence, which describes a relationship between certain gravity theories and quantum field theories. Most of my work thus far has concerned holographic RG flows between theories of different dimensions. This setup involves a quantum field theory compactified on a space with curled up directions, such that when one probes the theory at larger and larger distances it effectively becomes lower dimensional. Via AdS/CFT, one can translate this setup to a specific spacetime geometry and gain insight into its properties using tools such as entanglement entropy and the null energy condition. I’m very grateful to the Leinweber family who is generously supporting my work this summer.

Outside of physics I enjoy running and playing piano, and have a particular interest in medieval, renaissance, and baroque music.

My research work on black holes is characterized by the special attention given to the role of rotation and the nontrivial consequences of incorporating it in the description of black holes. In particular, for rotating and supersymmetric black holes in five dimensions, these consequences appear as nontrivial magnetic effects as well as complications in the usual story of the dynamics of matter fields embedded in the black hole geometries at hand.

Alan (Shih-Kuan) Chen studies the double-copy structure of scattering amplitudes with Professor Henriette Elvang. The interaction of fundamental particles, like electro-magnetic, weak, and strong interactions, is well described by quantum field theory when there is no gravity at present. While it is still mysterious how gravity can be incorporated with all the other interactions, at the observable level, their particle scatterings exhibit a neat relation known as double-copy. Alan is interested in what are the consistency re-quirements for there to be a double-copy, and how this machinery could be generalized. Starting with the leading order behavior at low energy and systematically adding higher energy corrections, the consistency requirement for 6 particles scatterings indicates that the possibilities are very restrictive – almost pin down to string theory. This opens the question of how those stringy structures are encoded in the double-copy.

**Graduating Students, Summer Reasearch Award**

My research focuses on the interaction of light, matter, and gravity through scattering processes. By searching for hidden structures in calculations, I aim to find new insights which make difficult computations more manageable. Specifically, I have explored how causality and unitarity bound the space of theories, as well as techniques for computing waveforms in classical general relativity and correlators in curved spacetimes, including anti-de Sitter. I have also studied generalizations of the double copy. I have given seminars about my research results at CalTech, Penn State, Yale, and the Institute of Advanced Study. I am excited to pursue a postdoctoral position at the Institute of Advanced Study in the Fall.