Estimates of Long-distance Contributions to the Bs→γγB_s \to \gamma \gamma Decay

We present first calculations of new long-distance contributions to $B_s \to \gamma \gamma$ decay due to intermediate $D_s$ and $D_s^*$ meson states. The relevant $\gamma$ vertices are estimated using charge couplings and transition moment couplings. Within our uncertainties, we find that these long-distance contributions could be comparable to the known short-distance contributions. Since they have different Cabibbo-Kobayashi-Maskawa matrix-element factors, there may be an interesting possibility of observing CP violation in this decay.Comment: 9 pages, 2 figures (embedded), all style files include

HQET form factors for Bs→KℓνB_s\to K\ell\nu decays beyond leading order

We compute semi-leptonic $B_s$ decay form factors using Heavy Quark Effective Theory on the lattice. To obtain good control of the $1/m_b$ expansion, one has to take into account not only the leading static order but also the terms arising at $O(1/m_b)$: kinetic, spin and current insertions. We show results for these terms calculated through the ratio method, using our prior results for the static order. After combining them with non-perturbative HQET parameters they can be continuum-extrapolated to give the QCD form factor correct up to $O(1/m_b^2)$ corrections and without $O(\alpha_s(m_b)^n)$ corrections.Comment: 7 pages, 4 figures. Proceedings of the 35th International Symposium on Lattice Field Theory, 18-24 June 2017, Granada, Spain; v2: small corrections, published versio

Fragmentation in a Positive Light

The organizers of the present symposium demonstrated a keen sense of topicality when they chose Diversity or Cacophony? New Sources of Norms in International Law? as the subject-matter of the 25th Anniversary Symposium of the Michigan Journal of International Law. For the last decade or so, the question whether the international legal order finds itself in the process of fragmentation, and if so, what the consequences of this development will be, has been a popular area of study for many jurists; most of them expressing their concern about what they consider to constitute a threat to the unity of international law-a unity which they believe to have existed or to still exist, or towards which, in their view, both the law-maker and the practitioner/judge ought at least to strive

Tribute to Eric Stein

My first encounter with Eric dates back forty years. In 1971 he taught a course at the Hague Academy of International Law. At that time, I was an assistant lecturer at the University of Innsbruck, had just submitted my Habilitationsschrift to the Law Faculty there, and, while waiting for my venia legendi to come forward, I wanted to spend a few weeks at what was-and probably still is-the most exciting place for young international law scholars to get together with hundreds of like-minded individuals and some of the most inspiring teachers worldwide. Eric certainly lived up to my expectation of what a leading American law professor would be like: His lectures were sharp and challenging, as was the entire man. I remember him as prim in his appearance, crystal clear in the presentation of his subject, but what I also remember (and what in retrospect, having known Eric and his gentle, Old Worldish manners for decades, I find surprising) is that in the afternoon seminars accompanying his lectures he struck me as extremely tough in his attempt to employ what I later got to know as the Socratic method vis-ii-vis an international student population more used to looking up in awe at the great figures in the field and not daring to say a word. Well, I did not let myself be intimidated; I took the floor a couple of times and must at least have made the impression of not being too shy to survive intellectual slugouts at U.S. law schools, because at the end of one session Eric called me to the podium, inquired who I was and where I came from, and then invited me to apply for admission to the LL.M. program at Michigan. I intended to follow this up after completing my Habilitation procedure, but immediately after I had done so I was offered the Chair of International Law at the University of Munich, and so I wrote to Eric begging him to understand my career choice, which he generously did

Fragmentation in a Positive Light

The organizers of the present symposium demonstrated a keen sense of topicality when they chose Diversity or Cacophony? New Sources of Norms in International Law? as the subject-matter of the 25th Anniversary Symposium of the Michigan Journal of International Law. For the last decade or so, the question whether the international legal order finds itself in the process of fragmentation, and if so, what the consequences of this development will be, has been a popular area of study for many jurists; most of them expressing their concern about what they consider to constitute a threat to the unity of international law-a unity which they believe to have existed or to still exist, or towards which, in their view, both the law-maker and the practitioner/judge ought at least to strive

Tribute to Eric Stein

My first encounter with Eric dates back forty years. In 1971 he taught a course at the Hague Academy of International Law. At that time, I was an assistant lecturer at the University of Innsbruck, had just submitted my Habilitationsschrift to the Law Faculty there, and, while waiting for my venia legendi to come forward, I wanted to spend a few weeks at what was-and probably still is-the most exciting place for young international law scholars to get together with hundreds of like-minded individuals and some of the most inspiring teachers worldwide. Eric certainly lived up to my expectation of what a leading American law professor would be like: His lectures were sharp and challenging, as was the entire man. I remember him as prim in his appearance, crystal clear in the presentation of his subject, but what I also remember (and what in retrospect, having known Eric and his gentle, Old Worldish manners for decades, I find surprising) is that in the afternoon seminars accompanying his lectures he struck me as extremely tough in his attempt to employ what I later got to know as the Socratic method vis-ii-vis an international student population more used to looking up in awe at the great figures in the field and not daring to say a word. Well, I did not let myself be intimidated; I took the floor a couple of times and must at least have made the impression of not being too shy to survive intellectual slugouts at U.S. law schools, because at the end of one session Eric called me to the podium, inquired who I was and where I came from, and then invited me to apply for admission to the LL.M. program at Michigan. I intended to follow this up after completing my Habilitation procedure, but immediately after I had done so I was offered the Chair of International Law at the University of Munich, and so I wrote to Eric begging him to understand my career choice, which he generously did