Syed Mehedi Hasan

মলম

Balm

তারা বলে আমাকে "রাজনৈতিক" হতে, বেরাদারি করতে। আমি মাথা কাত করে হ্যা বলে তাকায় তাকায় দেখি।

They tell me to be “political”—to play the brotherhood game: praise bought with praise, favor traded for favor. I tilt my head, say yes, and watch, and watch.

তারা আরো বলে বিজ্ঞান পেপার করতে। একটু কোল্যাব কোল্যাব মিষ্টি, আর গ্রান্ট গ্রান্ট গন্ধ। আমি মাথা কাত করে হ্যা বলে তাকায় তাকায় দেখি।

They tell me to do science papers—a little “collab-collab” sugar, a whiff of “grant-grant” perfume. I tilt my head, say yes, and watch, and watch.

তারা সুর বানাতে বলে চার মিনিটের কম আর তিন মিনিটের বেশি, যেখানে একটা ফোর বাই ফোর গান বসে যাবে অনায়াসে। আমি মাথা কাত করে হ্যা বলে তাকায় তাকায় দেখি।

They tell me to build a tune under four minutes and over three, where a song in four-four drops in without a fight. I tilt my head, say yes, and watch, and watch.

তারপর কাউরে কিছু না বলে ঘুমাই ছয় মাস কি এক বছর। ততোদিনে অনেক মলম বেচা হয়ে গেছে দুনিয়ায়।

Then, without a word to anyone, I sleep—six months, perhaps a year. By then, plenty of balm has been sold in the world.

তারা বলে মলমেই সব। মেশক আম্বরের শিশিটাও তো মলমেরই শিশি। যেনো মলমীর মধ্যে লুকায় থাকে মরমী। শিশিটা হাতে নিয়ে মৃগের পিছনে ছুটে ছুটে যাও হে শুদ্ধাচারী।

They say balm is everything. After all, the vial of musk and ambergris is just another vial of balm. As though a mystic lay hidden inside the balmist.. ha ha!... So take your vial, O man of purity, and run—run after the deer.

আমি আবার মাথা কাত করে তাকায় তাকায় দেখি।

Again, I tilt my head and watch, and watch.

Physics · Music · Philosophy

Syed Mehedi Hasan

I'm a theoretical particle physicist — I work out the precision frontier of quantum field theory. Away from the calculations, I compose music and write about the topics I find intriguing beyond my academic discipline.

  • PositionPostdoctoral Research Associate
  • InstituteInstitut für Theoretische Physik, Universität Regensburg
  • FieldsPrecision QCD · Mellin–Barnes · Feynman integrals
Syed Mehedi Hasan
Re s Im s
Mellin–Barnes contour
Physics

Precision calculations for colliders.

My work runs along three fronts — the analytic theory of multi-loop and phase-space integrals, the mathematics that makes them tractable, and the collider phenomenology they feed.

Theory
γ* γ* cut
RAD · Mellin–Barnes

Phase-space integrals

The Radial Angular Decomposition — real-emission phase-space integrals evaluated through multifold Mellin–Barnes representations and expressed in Goncharov polylogarithms.

γ*/Z ff
Massive form factors

Two-loop vacuum polarization

Second-order corrections to the massive form factors from two-loop vertex diagrams with a vacuum-polarization insertion — closing a problem open for about two decades.

ℓℓ′ γ* p h
EIC

SIDIS

NNLO phase-space integrals for semi-inclusive deep-inelastic scattering — precision theory for the coming Electron–Ion Collider.

Mathematics
v₁ v₂ v₃ v₄ ∫ dΩ
Mellin–Barnes

Four-denominator angular integrals

Angular phase-space integrals with four denominators through Mellin–Barnes — six- and seven-fold MB integrals solved analytically, to my knowledge a first in the literature.

qq̄ ℓ⁺ℓ⁻ γ*/Zg
Drell–Yan · LHC

Master integrals for Drell–Yan

All master integrals for the mixed QCD–EW corrections to Drell–Yan, with exact final-state lepton-mass dependence — the last missing piece for the neutral-current channel.

Phenomenology
ee pp γγ
Elastic ep · MUSE

Elastic ep scattering

NLO QED radiative corrections to elastic electron– and muon–proton scattering, with focus on the two-photon-exchange contribution.

μμ ee γ
MUonE · CERN

Muon–electron scattering

NNLO photonic and leptonic corrections, and the two-loop master integrals, for the MUonE experiment at CERN.

Selected results
MUonE pair-production acceptance study, theta_mu vs theta_e
MUonE. Pair-production background μ⁻e⁻→μ⁻e⁻e⁺e⁻ against the elastic curve (θμ vs θe) under successive acceptance cuts.  JHEP 11 (2021) 098
Elastic ep two-photon-exchange ratio R2gamma vs epsilon
Elastic ep. Two-photon-exchange ratio R2γ vs ε — CLAS (left) and OLYMPUS (right), our dipole/monopole form-factor results against data.  arXiv:2605.31123
Selected papers
2026

Radiative corrections to elastic lepton–proton scattering, with focus on two-photon-exchange diagrams

arXiv:2605.31123with D. Crowe, D. WackerotharXiv ↗
2025

Angular phase-space integrals with four denominators through Mellin–Barnes

JHEP 11 (2025) 152with T. Ahmed, A. RapakouliasarXiv ↗
2025

Phase-space integrals through the Mellin–Barnes representation

Phys. Rev. D 112 (2025) L051903with T. Ahmed, A. RapakouliasarXiv ↗
2025

NNLO phase-space integrals for semi-inclusive deep-inelastic scattering

Phys. Rev. D 112 (2025) 014020with T. Ahmed, S. Goyal, R. N. Lee, S.-O. Moch et al.arXiv ↗
2024

Two-loop vertices with vacuum polarization insertion

JHEP 01 (2024) 010with T. Ahmed, G. Crisanti, F. Gasparotto, P. MastroliaarXiv ↗
2021

NNLO virtual and real leptonic corrections to muon–electron scattering

JHEP 11 (2021) 098with E. Budassi, C. M. Carloni Calame, M. Chiesa et al.arXiv ↗
2020

Towards muon–electron scattering at NNLO

JHEP 11 (2020) 028with C. M. Carloni Calame, M. Chiesa, G. Montagna et al.arXiv ↗
2020

Master integrals for the mixed QCD–QED corrections to Drell–Yan production of a massive lepton pair

JHEP 11 (2020) 107with U. SchubertarXiv ↗
Curriculum Vitæ

A glimpse of the record.

Training, funding, and the computational toolkit at a glance — download the full CV (PDF) ↗, or see all publications on InspireHEP.

Education
Ph.D. in Theoretical Particle Physics
University at Buffalo, USA · 2019 High distinction
Advised by Prof. Doreen Wackeroth. Thesis: mixed QCD–electroweak corrections at O(ααs) to Drell–Yan production at hadron colliders.
M.Sc. in Physics
B.Sc. in Electrical and Electronic Engineering
University of Dhaka, Bangladesh · 2010
Appointments
Grants & Awards
  • 2026MIT Global Seed Funds grant — non-smooth large-N QFT via Mellin–Barnes, with Prof. Hong Liu (MIT)
  • 2026Academic Research Sabbatical (ARSP I), Regensburg — competitive, ≤ 5 awarded per round
  • 2019INFN Postdoctoral Fellowship
  • 2017Outstanding Teaching Assistant in Physics, University at Buffalo
Computational toolkit
C++FORTRANPythonRMathematicaFORMMBtoolsLiteRedFIREKIRAReduzeFeynArtsFeynCalcQGRAFTracer

Plus in-house Mathematica / FORTRAN codes for multi-loop master integrals, generalized-harmonic → Goncharov → classical polylogarithm conversion, and a GiNaC–FORTRAN bridge.