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Y. -P. Lee

Publications and source records attributed to Y. -P. Lee.

At least 19 recordsLinked to original sources
arXiv2024

Laboratory and astronomical discovery of cyanothioketene, NCCHCS, in the cold starless core TMC-1

We present the detection of cyanothioketene, NCCHCS, in the laboratory and toward TMC-1. This transient species was produced through a discharge of a gas mixture of CH2CHCN and CS2 using argon as carrier gas, and its rotational spectrum between 9 and 40 GHz was characterized using a Balle-Flygare narrowband-type Fourier-transform microwave spectrometer. A total of 21 rotational transitions were detected in the laboratory, all of them exhibiting hyperfine structure induced by the spin of the N nucleus. The spectrum for NCCHCS was predicted in the domain of our line surveys using the derived rotational and distortion constants. The detection in the cold starless core TMC-1 was based on the QUIJOTE line survey performed with the Yebes 40m radio telescope. Twenty-three lines were detected with K_a=0, 1, and 2 and J_u=9 up to 14. The derived column density is (1.2+/-0.1)e11 cm-2 for a rotational temperature of 8.5+/-1 K. The abundance ratio of thioketene and its cyano derivative, H2CCS/NCCHCS, is 6.5+/-1.3. Although ketene is more abundant than thioketene by about 15 times, its cyano derivative NCCHCO surprisingly is not detected with a 3sigma upper level to the column density of 3.0e10 cm-2, which results in an abundance ratio H2CCO/NCCHCO > 430. Hence, the chemistry of CN derivatives seems to be more favored for S-bearing than for O-bearing molecules. We carried out chemical modeling calculations and found that the gas-phase neutral-neutral reactions CCN + H2CS and CN + H2CCS could be a source of NCCHCS in TMC-1.

astro-ph.GA↗
arXiv2023

Quantum K-invariants and Gopakumar-Vafa invariants II. Calabi-Yau threefolds at genus zero

This is the second part of our ongoing project on the relations between Gopakumar-Vafa BPS invariants (GV) and quantum K-theory (QK) on the Calabi--Yau threefolds (CY3). We show that on CY3 a genus zero quantum K-invariant can be written as a linear combination of a finite number of Gopakumar--Vafa invariants with coefficients from an explicit ``multiple cover formula''. Conversely, GV can be determined by QK in a similar manner. The technical heart is a proof of a remarkable conjecture by Hans Jockers and Peter Mayr. This result is consistent with the ``virtual Clemens conjecture'' for the Calabi--Yau threefolds. A heuristic derivation of the relation between QK and GV via the virtual Clemens conjecture and the multiple cover formula is also given.

math.AG↗
arXiv2023

Higher Genus Quantum $K$--theory

We prove genus $g$ invariants in quantum $K$-theory are determined by genus zero invariants of a smooth stack in the spirit of K.~Costello's result in Gromov--Witten theory.

math.AG↗
arXiv2022

Quantum K-Theory I: Foundations

This work is devoted to the study of the foundations of quantum K-theory, a K-theoretic version of quantum cohomology theory. In particular, it gives a deformation of the ordinary K-ring K(X) of a smooth projective variety X, analogous to the relation between quantum cohomology and ordinary cohomology. This new quantum product also gives a new class of Frobenius manifolds.

math.AG↗
arXiv2017

A product formula for log Gromov-Witten invariants

The purpose of this short article is to prove a product formula relating the log Gromov-Witten invariants of $V \times W$ with those of $V$ and $W$ in the case the log structure on $V$ is trivial.

math.AG↗
arXiv2014

A proof of the Landau-Ginzburg/Calabi-Yau correspondence via the crepant transformation conjecture

We establish a new relationship (the MLK correspondence) between twisted FJRW theory and local Gromov-Witten theory in all genera. As a consequence, we show that the Landau-Ginzburg/Calabi-Yau correspondence is implied by the crepant transformation conjecture for Fermat type in genus zero. We use this to then prove the Landau-Ginzburg/Calabi-Yau correspondence for Fermat type, generalizing the results of A. Chiodo and Y. Ruan.

math.AG↗
arXiv2014

Invariance of quantum rings under ordinary flops: III

The paper is Part III of our ongoing project to study a case of Crepant Transformation Conjecture: K-equivalence Conjecture for ordinary flops. In this paper we prove the invariance of quantum rings for general ordinary flops, whose local models are certain non-split toric bundles over arbitrary smooth base. An essential ingredient in the proof is a quantum splitting principle, which reduces a statement in Gromov--Witten theory on non-split bundles to the case of split bundles.

math.AG↗
arXiv2012

A Mirror Theorem for the Mirror Quintic

The celebrated Mirror Theorem states that the genus zero part of the A model (quantum cohomology, rational curves counting) of the Fermat quintic threefold is equivalent to the B model (complex deformation, variation of Hodge structure) of its mirror dual orbifold. In this article, we establish a mirror-dual statement. Namely, the B model of the Fermat quintic threefold is shown to be equivalent to the A model of its mirror, and hence establishes the mirror symmetry as a true duality.

math.AG↗
arXiv2010

Algebraic cobordism of bundles on varieties

The double point relation defines a natural theory of algebraic cobordism for bundles on varieties. We construct a simple basis (over the rationals) of the corresponding cobordism groups over Spec(C) for all dimensions of varieties and ranks of bundles. The basis consists of split bundles over products of projective spaces. Moreover, we prove the full theory for bundles on varieties is an extension of scalars of standard algebraic cobordism.

math.AG↗
arXiv2008

Invariance of Gromov--Witten theory under a simple flop

We show that the generating functions of Gromov--Witten invariants with ancestors are invariant under a simple flop, for all genera, after an analytic continuation in the extended Kähler moduli space. This is a sequel to [LLW].

math.AG↗
arXiv2007

On independence of generators of the tautological rings

We prove that all monomials of $κ$-classes and $ψ$-classes are independent in $R^k(\ocM_{g,n})/R^k(\partial\ocM_{g,n})$ for all $k \leq [g/3]$. We also give a simple argument for $κ_l \neq 0$ in $R^l(\mathcal{M}_g)$ for $l \leq g-2$.

math.AG↗
arXiv2007

Flops, motives and invariance of quantum rings

For ordinary flops, the correspondence defined by the graph closure is shown to give equivalence of Chow motives and to preserve the Poincaré pairing. In the case of simple ordinary flops, this correspondence preserves the big quantum cohomology ring after an analytic continuation over the extended Kähler moduli space. For Mukai flops, it is shown that the birational map for the local models is deformation equivalent to isomorphisms. This implies that the birational map induces isomorphisms on the full quantum rings and all the quantum corrections attached to the extremal ray vanish.

math.AG↗
arXiv2006

Invariance of tautological equations II: Gromov--Witten theory

The aim of Part II is to explore the technique of invariance of tautological equations in the realm of Gromov--Witten theory. The main result is a proof of Invariance Theorem (Invariance Conjecture~1 in [14]), via the techniques from Gromov--Witten theory. It establishes some general inductive structure of the tautological rings, and provides a new tool to the study of this area.

math.AG↗