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• Post #2854390

  Registration is open until 1st of June for the #amplitudes summer school in #Southampton UK. This school is targeted at doctoral candidates in theoretical #physics and it covers modern topics in #quantumFieldTheory and amplitudes at a level at detail exceeding the unsual university lectures. #academicConference https://amplitudes.soton.ac.uk/school26/

• Post #2854389

  #paperOfTheDay "Critical Exponents from the Effective Average Action" from 1993 is one of the early works of what is now known as the functional renormalization group #frg , called at that time "exact non-perturbative evolution equation". In #quantumFieldTheory and statistical #physics , the behaviour of a system is different for different energy scales. This change is captured by the renormalization group: Changing the energy scale gives back a similar system...

• Post #2854388

  #paperOfTheDay "Integrating out Gluons in Flow equations" from 1996 is another early article about the functional renormalization group #frg , but this time applied to #QCD. The article is relatively long and contains many technicalities, but the main idea is the following: Like every #quantumFieldTheory , QCD contains "quantum fluctuations" on every energy scale, which can be integrated out from high to low energy with the help of a renormalization group flo...

• Post #2854387

  Registration is open for the workshop "The interplay of magnetic fields, nuclear #physics , and nucleosynthesis in neutron-star mergers and supernovae " at the ECT* in Trento, Italy. #academicConference #astrophysics https://www.ectstar.eu/workshops/the-interplay-of-magnetic-fields-nuclear-physics-and-nucleosynthesis-in-neutron-star-mergers-and-supernovae/

• Post #2854386

  #paperOfTheDay : "Sampling Pfaffian point processes and the symplectic Arnoldi method" from 2026. A Pfaffian is an algebraic object similar to a determinant: It eats a matrix and produces a number. The name is from Johann Friedrich Pfaff, who was one of the first to use it, and who was also the doctoral advisor of Karl Friedrich Gauss (also known as the prince of #mathematics ). A point process is a random process that consists of a discrete sequence of numbers. The concrete n...

• Post #2854385

  #paperOfTheDay is "Criterion for Dominance of Directional over Size Fluctuations in Destroying Order" from 1999. This article is about statistical #physics , which can as an effective model also be described by #quantumFieldTheory . Many practically relevant statistical models live in D=3 or D=2 spacial dimensions, and they describe a quantity (called "order parameter") which is itself a vector with N components. It can be that N=D, but other situations are co...

• Post #2854384

  #paperOfTheDay "Convergent Strong-Coupling Expansions from divergent weak-coupling perturbation theory" from 1995 studies the anharmonic oscillator, one of the most popular models for perturbation theory in theoretical #physics . Recall that with a potential V(x)= w/2*x^2, an object performs harmonic oscillations with frequency w, i.e. the trajectory (of a classical system) is a sine, or the #quantum oscillations are a complex exponential function. One now makes this potential...

• Post #1082567

  Registration is open for the 31st British Combinatorial Conference in Cardiff in Early July. Besides the plenary talks, there are minisymposia on various topics of #combinatorics and related areas of #mathematics , participants can submit abstracts for 20-min contributed talks. Registration is cheaper before 17 May. https://sites.google.com/view/bcc2026/home

• Post #711682

  This #paperOfTheDay is #computerScience : "A polynomial time, numerically stable integer relation algorithm" from 1992. This is the article that introduces the PSLQ algorithm. Given a n-component vector of real numbers x=(x_1, ..., x_n), an integer relation is a vector of integers (m_1, ..., m_n) such that m_1*x_1 + ... +m_n*x_n=0. Phrased differently, this means that one of the entries of x is a linear combination of the other entries, with rational coefficients. The task is...

• Post #525776

  #paperOfTheDay in my #dailyPaperChallenge is "Modular resurgent structures" from 2024. There are many relevant functions in #physics and #mathematics that are not expressible as convergent Taylor series (for a simple example, think of the square root function around the origin). If one attempts to compute these functions in perturbation theory, the resulting series are divergent, and it makes no sense to "insert a value" into them. However, it turns out that t...

• Post #525774

  #paperOfTheDay is "1/n Expansion: Calculation of the exponent nu in the order 1/n^3 by the Conformal Bootstrap method" from 1982. This paper is the first computation of the third-order correction in 1/N of the critical exponent of phi^4 #QuantumFieldTheory They use the mapping of the theory to a sigma model, which has the advantage of making explicit the N-dependence of diagrams. Then, they use "conformal bootstrap" to determine the sought-after values. This...

• Post #525773

  #paperOfTheDay : "The Brownian loop soup" from 2003. This is a #mathematics paper about random walks in the plane, but there is a famous concrete example from #physics : the 2-dimensional Brownian motion. Generically, the trajectory of such a random walk in a plane can intersect itself. A special case are the non-intersecting random walks. They can be obtained by taking a self-intersecting one, and whenever it intersects itself, one discards the "loop" part (s...

• Post #525770

  There's currently a #jobVacancy for a Postdoctoral Research Associate in Data-driven Modelling of Collective Cell Behaviour at the Maths institute, uni #Oxford. Deadline 20 March. https://my.corehr.com/pls/uoxrecruit/erq_jobspec_version_4.display_form

• Post #525769

  #paperOfTheDay is "The axial vector current in beta decay" from 1960. This paper was written at a time where the #quantumFieldTheory of the weak force was not known, and the interactions of elementary particles were quite mysterious. There were all sorts of experimental observations, and theorists had to come up with models to describe these results. In practice, this means you propose that certain fields exist, and how they interact, and then you do a calculation to show that...

• Post #525768

  For the #dailyPaperChallenge, I have read the #paperOfTheDay "Four-fermion interaction near four dimensions" from 1991. There are a few model systems that have been studied extensively in #quantumFieldTheory and wider theoretical #physics . Among them are the phi^4 theory (scalar field with quartic interaction) which can be treated perturbatively in 4-dimensional spacetime. The Gross-Neveu model (Fermions with quartic interaction) and nonlinear sigma model (scalars with non-mon...

• Post #525767

  This Sunday's #paperOfTheDay is "Solutions to Nonlinear Fractional Duffing Oscillator using MsDTM" from 2026. One possibility to derive #tropicalFieldTheory is a scaling limit of long range interacting field theory, see https://paulbalduf.com/research/tropical-field-theory/tropical-motivation/ . The equation of motion for such theories includes, in place of an ordinary Laplacian (i.e. second derivative), a non-integer derivative operator. There are numerous different w...

• Post #525766

  If you go to your backyard and measure the distances between all your trees and buildings, can you make a #map ? In principle that should be possible, but can one actually do the required numerical #optimization in practice? Yes, it works! I've done it and written a little example program in Mathematica to do it with your own data. It's always nice when you can use #mathematics to solve some funny practical problem. By the way, I think it would be nice to have this as an interact...

• Post #525765

  The #paperOfTheDay is the most bizarre one I have read in the whole #dailyPaperChallenge so far: It's "Geometrisches zur Abzählung der reellen Wurzeln algebraischer Gleichungen" from 1892. It is well known that a polynomial equation of order n has exactly n complex solutions. The present article deals with the question how many of these are real: Consider for example a quadratic equation, its curve is a parabola, and a parabola can have zero, one, or two intersections w...

• Post #525764

  Tuesday's #paperOfTheDay is related to the one about 4-fermion coupling a few days ago. Indeed, "The equivalence of the top quark condensate and the elementary Higgs field" from 1991 essentially deals with the same setup: They consider a #quantumFieldTheory with 4-fermion interaction in 4 dimensions, which is not renormalizable by power counting, but can be treated in the leading large-N limit. The conclusion is that in this limit, the theory can be solved more or less...

• Post #497551

  #paperOfTheDay is "Disquisitiones Generales circa seriem infinitam" by Carl Friedrich Gauss 1812. Probably one of the most influential #mathematics publications of all times. Gauss introduces a certain class of infinite series -- today known as Gaussian hypergeometric series -- which describe a new class of transcendental functions, namely the Gaussian hypergeometric function. Essentially all other transcendental functions known at that time are special cases of it. Gauss prove...