Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Impossibility of Baryogenesis at a Second Order Electroweak Phase
  Transition   We investigate whether baryogenesis is possible at a second order electroweak
phase transition. We find that under rather general conditions, the departure
from thermal equilibrium is suppressed by the expansion rate of the Universe,
and hence baryon production is also suppressed by the expansion rate. We
conclude that if no additional sources of departure from thermal equilibrium
such as topological defects are present, then electroweak baryogenesis is ruled
out if the phase transition is second order or crossover. However, a
non-vanishing net baryon to entropy ratio {\it is} generated, and we provide
both upper and lower bounds for the result. Our technique is also applicable to
other baryogenesis mechanisms taking place during and immediately after a
second order phase transition. We estimate the lowest value of the transition
energy scale for which the resulting baryon to entropy ratio might be large
enough to explain observations.

26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex