Edna and K.B. Weissman Building of Physical Sciences Room Drory Auditorium 14:15

SeminarsEffective Force-laws for thermal amorphous solids Yoav Pollack

SeminarsEffective Force-laws for thermal amorphous solids Yoav Pollack Edna and K.B. Weissman Building of Physical Sciences , Drory Auditorium 14:15

Wed

13Dec

Edna and K.B. Weissman Building of Physical Sciences Room Auditorium 10:45

Seminars“Observational Constraints on Dissipative Dark Matter” Eric David Kramer

Seminars“Observational Constraints on Dissipative Dark Matter” Eric David Kramer Edna and K.B. Weissman Building of Physical Sciences , Auditorium 10:45 10:45 Coffee
12:15 Lunch
Abstract: A recent direction in dark matter phenomenology has been to consider multi-component dark matter, containing subsectors with interesting interactions and structure. These include models where part of dark matter is dissipative. In these particular models, the dissipative subsector will cool to form a dark matter disk, whose size, density, and temperature can be predicted from the parameters of the model. I will discuss details of the model and of the disk formation process, as well as various observational constraints and possible evidence for such a disk. I will also discuss potential astrophysical constraints from recent Gaia data, and under what assumptions these constraints should be taken seriously.

Wed

13Dec

Edna and K.B. Weissman Building of Physical Sciences Room Auditorium 13:00

Seminars“A direct calculation of the lifetime of false vacua” Dr.Ryosuke Sato

Seminars“A direct calculation of the lifetime of false vacua” Dr.Ryosuke Sato Edna and K.B. Weissman Building of Physical Sciences , Auditorium 13:00 Abstract: The lifetime of false vacua can be calculated by Coleman's semiclassical method. This method implicitly uses a deformation of the potential. I will discuss an alternative approach to the calculation of the
lifetime of the false vacua.
References:
Direct Approach to Quantum Tunneling
Anders Andreassen, David Farhi, William Frost, Matthew D. Schwartz
Published in Phys.Rev.Lett. 117 (2016) no.23, 231601
e-Print: arXiv:1602.01102 [hep-th]
Precision decay rate calculations in quantum field theory
Anders Andreassen, David Farhi, William Frost, Matthew D. Schwartz
Published in Phys.Rev. D95 (2017) no.8, 085011
e-Print: arXiv:1604.06090 [hep-th]

Mon

18Dec

Edna and K.B. Weissman Building of Physical Sciences Room Drory Auditorium 14:15

SeminarsTurbulence in a Localized Puff in a Pipe Prof. Alex Yakhot

SeminarsTurbulence in a Localized Puff in a Pipe Prof. Alex Yakhot Edna and K.B. Weissman Building of Physical Sciences , Drory Auditorium 14:15 We have performed direct numerical simulations of transient turbulence in pipe flow for Re=2,250 which is established as a threshold of an equilibrium puff. We investigate the structure of an individual puff by considering three-dimensional snapshots across a long time-period. To assimilate the velocity data, we apply a conditional sampling based on the location of the maximum energy of the transverse (turbulent) motion. Specifically, at each time instance, we follow a turbulent puff by a three-dimensional moving-window centered at that location. We collected a snapshot-ensemble of the velocity fields acquired over 10,000 time instances (snapshots) inside the moving-window. The considered fow is intermittent and transitional. The velocity field inside the puff shows the dynamics of a developing turbulence. The localized puff is about of 12-15 pipe diameters long with almost laminar trailing and leading edges. In the puff core, despite the low Reynolds number, along the moving-window, it takes the downstream short distance of several pipe diameters to form the state of developed turbulence, when the turbulence statistics becomes similar to fully-developed turbulent pipe flow; the velocity profile becomes flat in the pipe core and logarithmic near the wall. It is shown that this “fully-developed turbulent slot” is very narrow, about two pipe diameters; it is localized and moves with a puff.