No Arabic abstract
We compute characteristic numbers of crepant resolutions of Weierstrass models corresponding to elliptically fibered fourfolds $Y$ dual in F-theory to a gauge theory with gauge group $G$. In contrast to the case of fivefolds, Chern and Pontryagin numbers of fourfolds are invariant under crepant birational maps. It follows that Chern and Pontryagin numbers are independent on a choice of a crepant resolution. We present the results for the Euler characteristic, the holomorphic genera, the Todd-genus, the $L$-genus, the $hat{A}$-genus, and the curvature invariant $X_8$ that appears in M-theory. We also show that certain characteristic classes are independent on the choice of the Kodaria fiber characterizing the group $G$. That is the case of $int_Y c_1^2 c_2$, the arithmetic genus, and the $hat{A}$-genus. Thus, it is enough to know $int_Y c_2^2$ and the Euler characteristic $chi(Y)$ to determine all the Chern numbers of an elliptically fibered fourfold. We consider the cases of $G=$ SU($n$) for ($n=2,3,4,5,6,7$), USp($4$), Spin($7$), Spin($8$), Spin($10$), G$_2$, F$_4$, E$_6$, E$_7$, or E$_8$.
We compute characteristic numbers of elliptically fibered fourfolds with multisections or non-trivial Mordell-Weil groups. We first consider the models of type E$_{9-d}$ with $d=1,2,3,4$ whose generic fibers are normal elliptic curves of degree $d$. We then analyze the characteristic numbers of the $Q_7$-model, which provides a smooth model for elliptic fibrations of rank one and generalizes the E$_5$, E$_6$, and E$_7$-models. Finally, we examine the characteristic numbers of $G$-models with $G=text{SO}(n)$ with $n=3,4,5,6$ and $G=text{PSU}(3)$ whose Mordell-Weil groups are respectively $mathbb{Z}/2mathbb{Z}$ and $mathbb{Z}/3 mathbb{Z}$. In each case, we compute the Chern and Pontryagin numbers, the Euler characteristic, the holomorphic genera, the Todd-genus, the L-genus, the A-genus, and the eight-form curvature invariant from M-theory.
We introduce special classes of non-commutative crepant resolutions (= NCCR) which we call steady and splitting. We show that a singularity has a steady splitting NCCR if and only if it is a quotient singularity by a finite abelian group. We apply our results to toric singularities and dimer models.
We study crepant resolutions of Weierstrass models of $text{SU}(2)!times!text{SU}(3)$-models, whose gauge group describes the non-abelian sector of the Standard Model. The $text{SU}(2)!times!text{SU}(3)$-models are elliptic fibrations characterized by the collision of two Kodaira fibers with dual graphs that are affine Dynkin diagrams of type $widetilde{text{A}}_1$ and $widetilde{text{A}}_2$. Once we eliminate those collisions that do not have crepant resolutions, we are left with six distinct collisions that are related to each other by deformations. Each of these six collisions has eight distinct crepant resolutions whose flop diagram is a hexagon with two legs attached to two adjacent nodes. Hence, we consider 48 distinct resolutions that are connected to each other by deformations and flops. We determine topological invariants---such as Euler characteristics, Hodge numbers, and triple intersections of fibral divisors---for each of the crepant resolutions. We analyze the physics of these fibrations when used as compactifications of M-theory and F-theory on Calabi--Yau threefolds yielding 5d ${mathcal N}=1$ and 6d ${mathcal N}=(1,0)$ supergravity theories respectively. We study the 5d prepotential in the Coulomb branch of the theory and check that the six-dimensional theory is anomaly-free and compatible with a 6d uplift from a 5d theory.
In this paper, we study splitting (or toric) non-commutative crepant resolutions (= NCCRs) of some toric rings. In particular, we consider Hibi rings, which are toric rings arising from partially ordered sets, and show that Gorenstein Hibi rings with class group $mathbb{Z}^2$ have a splitting NCCR. In the appendix, we also discuss Gorenstein toric rings with class group $mathbb{Z}$, in which case the existence of splitting NCCRs is already known. We especially observe the mutations of modules giving splitting NCCRs for the three dimensional case, and show the connectedness of the exchange graph.
In this paper, we study divisorial ideals of a Hibi ring which is a toric ring arising from a partially ordered set. We especially characterize the special class of divisorial ideals called conic using the associated partially ordered set. Using our description of conic divisorial ideals, we also construct a module giving a non-commutative crepant resolution (= NCCR) of the Segre product of polynomial rings. Furthermore, applying the operation called mutation, we give other modules giving NCCRs of it.