A possible correlation between EGRET Sources and an Air-Borne experiment

In 1989, an air-borne experiments (VEGA experiment) aiming at the detection of a few 10 GeV $\gamma$-ray were carried out. In these experiments, nine point-source candidates along the Galactic plane were reported. In these candidates, the five of five highest significance candidates positionally coincide with the EGRET galactic plane sources.Comment: 3 pages, latex(article,epsf), 1 figure. to appear in "Towards a Major Atmospheric Cerenkov Detector III", 243p, Universal Academy Press, Inc. Tokyo, Japa

A Quiver Construction of Symmetric Crystals

In the recent papers with Masaki Kashiwara, the author introduced the notion of symmetric crystals and presented the Lascoux-Leclerc-Thibon-Ariki type conjectures for the affine Hecke algebras of type $B$. Namely, we conjectured that certain composition multiplicities and branching rules for the affine Hecke algebras of type $B$ are described by using the lower global basis of symmetric crystals of $V_\theta(\lambda)$. In this paper, we prove the existence of crystal bases and global bases of $V_\theta(0)$ for any symmetric quantized Kac-Moody algebra by using a geometry of quivers (with a Dynkin diagram involution). This is analogous to George Lusztig's geometric construction of $U_v^-$ and its lower global basis.Comment: 33 page

Rigid modules and ICE-closed subcategories in quiver representations

We introduce image-cokernel-extension-closed (ICE-closed) subcategories of module categories. This class unifies both torsion classes and wide subcategories. We show that ICE-closed subcategories over the path algebra of Dynkin type are in bijection with basic rigid modules, that ICE-closed subcategories are precisely torsion classes in some wide subcategories, and that the number does not depend on the orientation of the quiver. We give an explicit formula of this number for each Dynkin type, and in particular, it is equal to the large Schr\"oder number for type A case.Comment: 16 pages, ver 3, Added new proof using exceptional sequences and new results (Section 5). comments welcom

Recent results from TRISTAN

The TRISTAN results from 1994 to 1995 are reviewed in this report. The physics results dominated the $\gamma \gamma$ physics. Therefore, only these are selected in this article. We have systematically investigated jet productions, the $\gamma$-structure function, and charm pair productions in $\gamma \gamma$ processes. The results, discussions, and future prospects are presented.Comment: 14 pages, latex, 12 figures, mpeg simulations available at http://topsun1.kek.jp/~enomoto/ssi95.p

New Tagging Method of B Flavor of Neutral B Meson in CP Violation Measurement in Asymmetric B-Factory Experiment

In CP violation measurements in asymmetric B-factory experiments, a determination of the B flavor of the neutral B mesons is necessary. A new method to this purpose using only three vectors of charged particles has been developed. This method (weighted charge method) does not require either lepton identification or charged-kaon identification. The tagging efficiency, probability for incorrect tagging, and effective tagging efficiency of this method are 43.1, 18.3, and 17.3\%, respectively.Comment: 6 pages, Latex format (article), 3 figures, published in J. of Phys. Soc. Jpn. Vol. 63 (1994) 354

Classification of the Irreducible Representations of Affine Hecke Algebras of Type B_2 with unequal parameters

We classify the finite dimensional irreducible representations of affine Hecke algebras of type B_2 with unequal parameters.Comment: 13 page

Classifications of exact structures and Cohen-Macaulay-finite algebras

We give a classification of all exact structures on a given idempotent complete additive category. Using this, we investigate the structure of an exact category with finitely many indecomposables. We show that the relation of the Grothendieck group of such a category is generated by AR conflations. Moreover, we obtain an explicit classification of (1) Gorenstein-projective-finite Iwanaga-Gorenstein algebras, (2) Cohen-Macaulay-finite orders, and more generally, (3) cotilting modules $U$ with $^\perp U$ of finite type. In the appendix, we develop the AR theory of exact categories over a noetherian complete local ring, and relate the existence of AR conflations to the AR duality and dualizing varieties.Comment: 27 pages, Final versio

Relations for Grothendieck groups and representation-finiteness

For an exact category $\mathcal{E}$, we study the Butler's condition "AR=Ex": the relation of the Grothendieck group of $\mathcal{E}$ is generated by Auslander-Reiten conflations. Under some assumptions, we show that AR=Ex is equivalent to that $\mathcal{E}$ has finitely many indecomposables. This can be applied to functorially finite torsion(free) classes and contravariantly finite resolving subcategories of the module category of an artin algebra, and the category of Cohen-Macaulay modules over an order which is Gorenstein or has finite global dimension. Also we showed that under some weaker assumption, AR=Ex implies that the category of syzygies in $\mathcal{E}$ has finitely many indecomposables.Comment: 16 page

Monobrick, a uniform approach to torsion-free classes and wide subcategories

For a length abelian category, we show that all torsion-free classes can be classified by using only the information on bricks, including non functorially-finite ones. The idea is to consider the set of simple objects in a torsion-free class, which has the following property: it is a set of bricks where every non-zero map between them is an injection. We call such a set a monobrick. In this paper, we provide a uniform method to study torsion-free classes and wide subcategories via monobricks. We show that monobricks are in bijection with left Schur subcategories, which contains all subcategories closed under extensions, kernels and images, thus unifies torsion-free classes and wide subcategories. Then we show that torsion-free classes bijectively correspond to cofinally closed monobricks. Using monobricks, we deduce several known results on torsion(-free) classes and wide subcategories (e.g. finiteness result and bijections) in length abelian categories, without using $\tau$-tilting theory. For Nakayama algebras, left Schur subcategories are the same as subcategories closed under extensions, kernels and images, and we show that its number is related to the large Schr\"oder number.Comment: 28 pages, final version. a minor correction. to appear in Adv. Mat

Classifying substructures of extriangulated categories via Serre subcategories

We give a classification of substructures (= closed subbifunctors) of a given skeletally small extriangulated category by using the category of defects, in a similar way to the author's classification of exact structures of a given additive category. More precisely, for an extriangulated category, possible substructures are in bijection with Serre subcategories of an abelian category consisting of defects of conflations. As a byproduct, we prove that for a given skeletally small additive category, the poset of exact structures on it is isomorphic to the poset of Serre subcategories of some abelian category.Comment: 12 pages, comments welcom