<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title></title>
</head>
<body style="font-family:Arial;font-size:14px">
<p><br>
<br>
COLOQUIO (EXTRA) DEL DEPARTAMENTO DE FÍSICA FCEYN - UBA<br>
<br>
En el Aula Seminario, 1er piso, Pab. I, <br>
<br>
Hoy Martes 19/11, 14hs:<br>
<br>
ALEJANDRO KIEVSKY<br>
<br>
ISTITUTO NAZIONALE DE FISICA NUCLEARE - PISA <br>
<br>
<span style="color: rgb(31, 28, 27); font-family: 'Sans Serif'; font-size: 13px; white-space: pre-wrap;">UNIVERSALITY IN SHALLOW N-BOSON STATES<br>
<br>
The Efimov effect is a remarkable phenomenon of the</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> three-boson system: when the two-body scattering length</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> is large a sequence of arbitrary shallow three-body bound states</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> appear with accumulation point at E=0. This feature was discovered</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> by V. Efimov in 1970 and triggered an intense theoretical as</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> well as an experimental activity to study this phenomenon. Though</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> the work by Efimov was originated in nuclear phyiscs, much of</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> the experimental activity is at present done in the sector of</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> ultracold atoms. From a theoretical point of view the Efimov</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> effect is characterized by a discrete scaling symmetry and</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> the Efimov spectrum is governed by an universal function.</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> In the present talk I will analyze the evolution of the Efimov</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> spectrum with N, the number of bosons. I will show that the</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> discrete scaling symmetry strongly constrains the spectrum of</span></p>
<p style="white-space: pre-wrap; font-family: 'Sans Serif'; font-size: 13px; margin: 0px;"><span style="color: rgb(31, 28, 27);"> the N-boson system. Some universal ratios between energy levels</span></p>
<p><span style="color: rgb(31, 28, 27); font-family: 'Sans Serif'; font-size: 13px; white-space: pre-wrap;"> are derived.</span><br>
<br></p>
</body>
</html>