Hi, this is Shubhrajit, a 2nd-year Ph.D. student in Mathematics at The University of Chicago. I'm working with Professor Frank Calegari.
Prior to this, I earned my Master's in Mathematics from The University of British Columbia (2022–2024), working under the supervision of Sujatha Ramdorai.
My master's thesis, titled "On Some Congruences of Zeta and \(L\)-values at Negative Odd Integers" explores some new congruences of certain \( L \)-values using \( p \)-adic \( L \)-functions.
Before that, I did a BS in Mathematics and Computer Science(2019-2022) at the Chennai Mathematical Institute in India.
Papers (Selected)
On Monic Abelian Trace-One Cubic Polynomials (Submitted)
We compute the asymptotic number of monic trace-one integral polynomials with Galois group \( C_3 \) and bounded height. For such polynomials we compute a height function coming from toric geometry and introduce a parametrization using the quadratic cyclotomic field \( \mathbb{Q}(\sqrt{-3}) \). We also give a formula for the number of polynomials of the form \( t^3 - t^2 + at + b \in \mathbb{Z}[t] \) with Galois group \( C_3 \) for a fixed integer \( a \).
Correlations of error terms for weighted prime counting functions
Standard prime-number counting functions, such as \( \psi(x) \), \( \theta(x) \), and \( \pi(x) \), have error terms with limiting logarithmic distributions once suitably normalized. The same is true of weighted versions of those sums, like \( \pi_r(x) = \sum_{p\le x} \frac1p \) and \( \pi_\ell(x) = \sum_{p\le x} \log(1-\frac1p)^{-1} \), that were studied by Mertens. These limiting distributions are all identical, but passing to the limit loses information about how these error terms are correlated with one another. In this paper, we examine these correlations, showing, for example, that persistent inequalities between certain pairs of normalized error terms are equivalent to the Riemann hypothesis (RH). Assuming both RH and LI, the linear independence of the positive imaginary parts of the zeros of \( \zeta(s) \), we calculate the logarithmic densities of the set of real numbers for which two different error terms have prescribed signs. For example, we conditionally show that \( \psi(x) - x \) and \( \sum_{n\le x} \frac{\Lambda(n)}n - (\log x - C_0) \) have the same sign on a set of logarithmic density \( \approx 0.9865 \).
On Some Congruences of L-values at Negative Odd Integers (In preparation, based on my master's thesis)
In this thesis, we establish congruences for values of Dedekind Zeta functions attached to a specific family of totally real fields. Our main theorem generalizes [7, Proposition 2.5]. The proof relies on Iwasawa's construction of \( p \)-adic \( L \)-functions and an application of Local Class Field Theory. As a consequence, we derive a criterion for the \( p \)-indivisibility of generalized Bernoulli numbers \( B_{n,\chi} \) associated with Dirichlet characters \( \chi \) of \( p \)-power order, the triviality of \( p \)-torsion in certain even K-groups of specific totally real fields, and congruence modulo \( p \) between Euler characteristic of certain arithmetic groups. Our findings demonstrate the applicability of similar methods to establish congruences for Dirichlet \( L \)-values at negative odd integers, provided that the corresponding Dirichlet characters satisfy specific congruence criteria modulo a prime \( p \). Our results generalize and offer an alternate approach to some congruences demonstrated in [35].
AI Benchmarking
QEDBENCH: Quantifying the Alignment Gap in Automated Evaluation of University-Level Mathematical Proofs
As Large Language Models (LLMs) saturate elementary benchmarks, the research frontier has shifted from generation to the reliability of automated evaluation. We demonstrate that standard "LLM-as-a-Judge" protocols suffer from a systematic Alignment Gap when applied to upper-undergraduate to early graduate level mathematics. To quantify this, we introduce QEDBench, the first large-scale dual-rubric alignment benchmark to systematically measure alignment with human experts on university-level math proofs by contrasting course-specific rubrics against expert common knowledge criteria. By deploying a dual-evaluation matrix (7 judges x 5 solvers) against 1,000+ hours of human evaluation, we reveal that certain frontier evaluators like Claude Opus 4.5, DeepSeek-V3, Qwen 2.5 Max, and Llama 4 Maverick exhibit significant positive bias (up to +0.18, +0.20, +0.30, +0.36 mean score inflation, respectively). Furthermore, we uncover a critical reasoning gap in the discrete domain: while Gemini 3.0 Pro achieves state-of-the-art performance (0.91 average human evaluation score), other reasoning models like GPT-5 Pro and Claude Sonnet 4.5 see their performance significantly degrade in discrete domains. Specifically, their average human evaluation scores drop to 0.72 and 0.63 in Discrete Math, and to 0.74 and 0.50 in Graph Theory. In addition to these research results, we also release QEDBench as a public benchmark for evaluating and improving AI judges. Our benchmark is publicly published at https://github.com/qqliu/Yale-QEDBench.
Old Research Projects
Microsoft Research Internship
Advisor: Amit Deshpande
Nov 2021 - Feb 2022
Visiting Students' Research Programme (VSRP) 2021
Advisor: Eknath Ghate. Topic: The Bloch-Kato Conjecture
May - Jun 2021
Research Talks
Integer Polynomials and Toric Geometry
UBC Number Theory Seminar 2023-24 (Slides). Based on work with Andrew O'Desky.