COALESCENCE PHENOMENON OF QUANTUM COHOMOLOGY OF GRASSMANNIANS AND THE DISTRIBUTION OF PRIME NUMBERS GIORDANO COTTI(†) Abstract. The occurrence and frequency of a phenomenon of resonance (namely the coalescence of some Dubrovin canonical coordinates) in the locus of Small Quantum Cohomology of complex Grass- mannians is studied. It is shown that surprisingly this frequency is strictly subordinate and highly influenced by the distribution of prime numbers. Two equivalent formulations of the Riemann Hypoth- esis are given in terms of numbers of complex Grassmannians without coalescence: the former as a constraint on the disposition of singularities of the analytic continuation of the Dirichlet series associ- ated to the sequence counting non-coalescing Grassmannians, the latter as asymptotic estimate (whose error term cannot be improved) for their distribution function. Contents Notations 2 1. Introduction and Results3 1.1. Plan of the paper. 6 2. Frobenius Manifolds and Quantum Cohomology6 2.1. Semisimple Frobenius Manifolds8 2.2. Gromov-Witten Theory and Quantum Cohomology9 3. Quantum Satake Principle 11 3.1. Results on classical cohomology of Grassmannians 11 3.2. Quantum Cohomology of G(k, n) 15 4. Frequency of Coalescence Phenomenon in QH•(G(k, n)) 16 4.1. Results on vanishing sums of roots of unity 17 4.2. Characterization of coalescing Grassmannians 18 4.3. Dirichlet series associated to non-coalescing Grassmannians, and their rareness 19 5. Distribution functions of non-coalescing Grassmannians, and equivalent form of the Riemann Hypothesis 22 References 24 arXiv:1608.06868v2 [math-ph] 21 Sep 2016 (†) SISSA, Via Bonomea, 265 - 34136 Trieste ITALY E-mail address:
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