Journal article 1136 views 149 downloads
EFT beyond the horizon: stochastic inflation and how primordial quantum fluctuations go classical
Journal of High Energy Physics, Volume: 2015, Issue: 3
Swansea University Author:
Gianmassimo Tasinato
DOI (Published version): 10.1007/JHEP03(2015)090
Abstract
We identify the effective theory describing inflationary super-Hubble scales and show it to be a special case of effective field theories appropriate to open systems. Open systems allow information to be exchanged between the degrees of freedom of interest and those that are integrated out, such as...
Published in: | Journal of High Energy Physics |
---|---|
ISSN: | 1029-8479 |
Published: |
2015
|
Online Access: |
Check full text
|
URI: | https://cronfa.swan.ac.uk/Record/cronfa21641 |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
first_indexed |
2015-05-22T02:03:42Z |
---|---|
last_indexed |
2018-05-12T12:49:33Z |
id |
cronfa21641 |
recordtype |
SURis |
fullrecord |
<?xml version="1.0"?><rfc1807><datestamp>2018-05-12T07:22:52.9041109</datestamp><bib-version>v2</bib-version><id>21641</id><entry>2015-05-21</entry><title>EFT beyond the horizon: stochastic inflation and how primordial quantum fluctuations go classical</title><swanseaauthors><author><sid>cb754b073d1e4949c5e3db97744d3301</sid><ORCID>0000-0002-9835-4864</ORCID><firstname>Gianmassimo</firstname><surname>Tasinato</surname><name>Gianmassimo Tasinato</name><active>true</active><ethesisStudent>false</ethesisStudent></author></swanseaauthors><date>2015-05-21</date><deptcode>SPH</deptcode><abstract>We identify the effective theory describing inflationary super-Hubble scales and show it to be a special case of effective field theories appropriate to open systems. Open systems allow information to be exchanged between the degrees of freedom of interest and those that are integrated out, such as for particles moving through a fluid. Strictly speaking they cannot in general be described by an effective lagrangian; rather the appropriate `low-energy' limit is instead a Lindblad equation describing the evolution of the density matrix of the slow degrees of freedom. We derive the equation relevant to super-Hubble modes of quantum fields in near-de Sitter spacetimes and derive two implications. We show the evolution of the diagonal density-matrix elements quickly approaches the Fokker-Planck equation of Starobinsky's stochastic inflationary picture. This provides an alternative first-principles derivation of this picture's stochastic noise and drift, as well as its leading corrections. (An application computes the noise for systems with a sub-luminal sound speed.) We argue that the presence of interactions drives the off-diagonal density-matrix elements to zero in the field basis. This shows why the field basis is the `pointer basis' for the decoherence of primordial quantum fluctuations while they are outside the horizon, thus allowing them to re-enter as classical fluctuations, as assumed when analyzing CMB data. The decoherence process is efficient, occurring after several Hubble times even for interactions as weak as gravitational-strength. Crucially, the details of the interactions largely control only the decoherence time and not the nature of the final late-time stochastic state, much as interactions can control the equilibration time for thermal systems but are largely irrelevant to the properties of the resulting equilibrium state.</abstract><type>Journal Article</type><journal>Journal of High Energy Physics</journal><volume>2015</volume><journalNumber>3</journalNumber><publisher/><issnElectronic>1029-8479</issnElectronic><keywords/><publishedDay>31</publishedDay><publishedMonth>3</publishedMonth><publishedYear>2015</publishedYear><publishedDate>2015-03-31</publishedDate><doi>10.1007/JHEP03(2015)090</doi><url/><notes/><college>COLLEGE NANME</college><department>Physics</department><CollegeCode>COLLEGE CODE</CollegeCode><DepartmentCode>SPH</DepartmentCode><institution>Swansea University</institution><apcterm/><lastEdited>2018-05-12T07:22:52.9041109</lastEdited><Created>2015-05-21T20:16:33.1347240</Created><path><level id="1">Faculty of Science and Engineering</level><level id="2">School of Biosciences, Geography and Physics - Physics</level></path><authors><author><firstname>C. P.</firstname><surname>Burgess</surname><order>1</order></author><author><firstname>R.</firstname><surname>Holman</surname><order>2</order></author><author><firstname>G.</firstname><surname>Tasinato</surname><order>3</order></author><author><firstname>M.</firstname><surname>Williams</surname><order>4</order></author><author><firstname>Gianmassimo</firstname><surname>Tasinato</surname><orcid>0000-0002-9835-4864</orcid><order>5</order></author></authors><documents><document><filename>0021641-25072016163504.pdf</filename><originalFilename>EFT_beyond_the_horizon.pdf</originalFilename><uploaded>2016-07-25T16:35:04.5670000</uploaded><type>Output</type><contentLength>676413</contentLength><contentType>application/pdf</contentType><version>Version of Record</version><cronfaStatus>true</cronfaStatus><embargoDate>2016-07-25T00:00:00.0000000</embargoDate><documentNotes>Open access funded by SCOAP</documentNotes><copyrightCorrect>true</copyrightCorrect></document></documents><OutputDurs/></rfc1807> |
spelling |
2018-05-12T07:22:52.9041109 v2 21641 2015-05-21 EFT beyond the horizon: stochastic inflation and how primordial quantum fluctuations go classical cb754b073d1e4949c5e3db97744d3301 0000-0002-9835-4864 Gianmassimo Tasinato Gianmassimo Tasinato true false 2015-05-21 SPH We identify the effective theory describing inflationary super-Hubble scales and show it to be a special case of effective field theories appropriate to open systems. Open systems allow information to be exchanged between the degrees of freedom of interest and those that are integrated out, such as for particles moving through a fluid. Strictly speaking they cannot in general be described by an effective lagrangian; rather the appropriate `low-energy' limit is instead a Lindblad equation describing the evolution of the density matrix of the slow degrees of freedom. We derive the equation relevant to super-Hubble modes of quantum fields in near-de Sitter spacetimes and derive two implications. We show the evolution of the diagonal density-matrix elements quickly approaches the Fokker-Planck equation of Starobinsky's stochastic inflationary picture. This provides an alternative first-principles derivation of this picture's stochastic noise and drift, as well as its leading corrections. (An application computes the noise for systems with a sub-luminal sound speed.) We argue that the presence of interactions drives the off-diagonal density-matrix elements to zero in the field basis. This shows why the field basis is the `pointer basis' for the decoherence of primordial quantum fluctuations while they are outside the horizon, thus allowing them to re-enter as classical fluctuations, as assumed when analyzing CMB data. The decoherence process is efficient, occurring after several Hubble times even for interactions as weak as gravitational-strength. Crucially, the details of the interactions largely control only the decoherence time and not the nature of the final late-time stochastic state, much as interactions can control the equilibration time for thermal systems but are largely irrelevant to the properties of the resulting equilibrium state. Journal Article Journal of High Energy Physics 2015 3 1029-8479 31 3 2015 2015-03-31 10.1007/JHEP03(2015)090 COLLEGE NANME Physics COLLEGE CODE SPH Swansea University 2018-05-12T07:22:52.9041109 2015-05-21T20:16:33.1347240 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Physics C. P. Burgess 1 R. Holman 2 G. Tasinato 3 M. Williams 4 Gianmassimo Tasinato 0000-0002-9835-4864 5 0021641-25072016163504.pdf EFT_beyond_the_horizon.pdf 2016-07-25T16:35:04.5670000 Output 676413 application/pdf Version of Record true 2016-07-25T00:00:00.0000000 Open access funded by SCOAP true |
title |
EFT beyond the horizon: stochastic inflation and how primordial quantum fluctuations go classical |
spellingShingle |
EFT beyond the horizon: stochastic inflation and how primordial quantum fluctuations go classical Gianmassimo Tasinato |
title_short |
EFT beyond the horizon: stochastic inflation and how primordial quantum fluctuations go classical |
title_full |
EFT beyond the horizon: stochastic inflation and how primordial quantum fluctuations go classical |
title_fullStr |
EFT beyond the horizon: stochastic inflation and how primordial quantum fluctuations go classical |
title_full_unstemmed |
EFT beyond the horizon: stochastic inflation and how primordial quantum fluctuations go classical |
title_sort |
EFT beyond the horizon: stochastic inflation and how primordial quantum fluctuations go classical |
author_id_str_mv |
cb754b073d1e4949c5e3db97744d3301 |
author_id_fullname_str_mv |
cb754b073d1e4949c5e3db97744d3301_***_Gianmassimo Tasinato |
author |
Gianmassimo Tasinato |
author2 |
C. P. Burgess R. Holman G. Tasinato M. Williams Gianmassimo Tasinato |
format |
Journal article |
container_title |
Journal of High Energy Physics |
container_volume |
2015 |
container_issue |
3 |
publishDate |
2015 |
institution |
Swansea University |
issn |
1029-8479 |
doi_str_mv |
10.1007/JHEP03(2015)090 |
college_str |
Faculty of Science and Engineering |
hierarchytype |
|
hierarchy_top_id |
facultyofscienceandengineering |
hierarchy_top_title |
Faculty of Science and Engineering |
hierarchy_parent_id |
facultyofscienceandengineering |
hierarchy_parent_title |
Faculty of Science and Engineering |
department_str |
School of Biosciences, Geography and Physics - Physics{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Physics |
document_store_str |
1 |
active_str |
0 |
description |
We identify the effective theory describing inflationary super-Hubble scales and show it to be a special case of effective field theories appropriate to open systems. Open systems allow information to be exchanged between the degrees of freedom of interest and those that are integrated out, such as for particles moving through a fluid. Strictly speaking they cannot in general be described by an effective lagrangian; rather the appropriate `low-energy' limit is instead a Lindblad equation describing the evolution of the density matrix of the slow degrees of freedom. We derive the equation relevant to super-Hubble modes of quantum fields in near-de Sitter spacetimes and derive two implications. We show the evolution of the diagonal density-matrix elements quickly approaches the Fokker-Planck equation of Starobinsky's stochastic inflationary picture. This provides an alternative first-principles derivation of this picture's stochastic noise and drift, as well as its leading corrections. (An application computes the noise for systems with a sub-luminal sound speed.) We argue that the presence of interactions drives the off-diagonal density-matrix elements to zero in the field basis. This shows why the field basis is the `pointer basis' for the decoherence of primordial quantum fluctuations while they are outside the horizon, thus allowing them to re-enter as classical fluctuations, as assumed when analyzing CMB data. The decoherence process is efficient, occurring after several Hubble times even for interactions as weak as gravitational-strength. Crucially, the details of the interactions largely control only the decoherence time and not the nature of the final late-time stochastic state, much as interactions can control the equilibration time for thermal systems but are largely irrelevant to the properties of the resulting equilibrium state. |
published_date |
2015-03-31T03:25:42Z |
_version_ |
1763750908630401024 |
score |
11.021648 |