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BtSM Event Announcements

  1. May 2, 2008 #1

    Doc Al

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    This sticky is for announcements of pertinent scientific events, such as conferences, seminars, or public talks. This sticky may also be used to inform readers about papers, reviews, books, or conference talks involving forum members.
     
    Last edited: May 3, 2008
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  3. May 3, 2008 #2

    Hans de Vries

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    Congratulations Richard Obousy

    Congratulations to long time PF member Richard Obousy with his new paper on
    the arXiv. Richard is a graduate student with Gerald Cleaver.

    Radius Destabilization in Five Dimensional Orbifolds from Lorentz Violating Fields
    Authors: Richard K Obousy, Gerald Cleaver
    Abstract: One of the challenges in connecting higher dimensional theories to cosmology is stabilization of the moduli fields. We investigate the role of a Lorentz violating vector field in the context of stabilization. Specifically, we compute the one loop Casimir energy in Randall-Sundrum 5-dimensional (non-supersymmetric) S^1/ Z_2 orbifolds resulting from the interaction of a real scalar field with periodic boundary conditions with a Lorentz violating vector field. We find that the result is an enhanced attractive Casimir force. Hence, for stability, positive contributions to the Casimir force from branes and additional fields would be required to counter the destabilizing, attractive effect of Lorentz violating fields.


    Regards, Hans
     
    Last edited: May 3, 2008
  4. May 3, 2008 #3

    marcus

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    Last edited: May 3, 2008
  5. May 3, 2008 #4

    marcus

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    QG conference

    http://www.maths.nottingham.ac.uk/r...ntum_geometry_and_quantum_gravity_conference/
    QG2 2008 Quantum Geometry and Quantum Gravity Conference
    Monday June 30th - Friday July 4th 2008
    University of Nottingham, UK
    Topics:

    *Quantum gravity, including loop quantum gravity, spin foam models, 1+1 and 2+1 quantum gravity, perturbative and discrete approaches. Quantum cosmology.


    *Quantum geometry, including physical aspects of non-commutative geometry, quantum groups and quantum topology. Non-commutative field theory and deformed special relativity.

    Some of the speakers and talks are already listed at the site.
     
    Last edited: May 3, 2008
  6. May 3, 2008 #5
    Thanks for the congrats Hans!
    Its nice to know you guys keep an eye out for PF members new papers.

    Richard
     
  7. May 6, 2008 #6

    Gokul43201

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    This is the last week for registration.

    http://www.math.upenn.edu/StringPhenom2008/
     
  8. May 13, 2008 #7

    marcus

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    Oporto meeting on Approaches to Quantum Gravity--what can we learn?

    http://faraday.fc.up.pt/omgtp2008/
    Every year there is the Oporto Meeting on Geometry Topology and Physics. This year the theme of the Oporto Meeting will be Approaches to Quantum Gravity.

    There will be four main speakers. We can see the titles of their talks and find (more or less) corresponding papers that they have already posted on arxiv. So we can easily find current research papers which Oporto, in effect, puts the spotlight on. Let's see what we can learn by studying the program of four main talks.

    Recall that QG is not a fixed academic subject but is dynamically changing. How experts and active researchers in the field see it can change considerably over the course of a few years, or even from year to year.

    MAIN SPEAKERS
    The main speakers will each give a minicourse of three one-hour lectures.

    Ali CHAMSEDDINE (American U. of Beirut & IHES, Bures-sur-Yvette)
    Classification of discrete noncommutative geometries and the uniqueness of the standard model

    Steven GIDDINGS (University of California, Santa Barbara)
    Probing nonperturbative gravity: black holes, locality, and cosmology

    Renate LOLL (Utrecht University)
    Quantum Gravity from Causal Dynamical Triangulations

    Thomas THIEMANN (Max Planck Institute for Gravitational Physics, Golm)
    Loop Quantum Gravity
     
    Last edited: May 13, 2008
  9. May 13, 2008 #8

    marcus

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    Ali Chamseddine, Classification of discrete noncommutative geometries and the uniqueness of the standard model

    Abstract:

    Assuming that space-time is a product of a continuous four-dimensional manifold times a discrete space F, we classify the irreducible geometries F consistent with imposing reality and chiral conditions on spinors. Remarkably we find that the noncommutative geometry of the standard model results almost uniquely, with all the necessary details. In particular we prove that the number of fermions per generation is 16, the square of an even integer. The spectral action of this geometry is constructed, and the model is analyzed.
    ==================================

    Steven Giddings, Probing nonperturbative gravity: black holes, locality, and cosmology

    Abstract:

    I will describe conflict of general physical principles in the non-perturbative regime of quantum gravity, particularly involving black holes. Notably, this conflict suggests reexamination of the principle of locality. If there is time, some related aspects of cosmology will be discussed.
    ====================================

    Renate Loll, Quantum Gravity from Causal Dynamical Triangulations

    Abstract:

    I discuss motivation, implementation and results of the nonperturbative approach to quantum gravity based on Causal Dynamical Triangulations, including the recent reconstruction of de Sitter space from quantum fluctuations.
    ======================================

    Thomas Thiemann, Loop Quantum Gravity

    Abstract:

    We give an introduction to the main concepts of Loop Quantum Gravity
    ===============endquote=======================

    These are the abstracts. Each of the four main speakers will give a three-hour mini-course on these topics spread out over the several days of the conference (10-13 July). Let's see what papers we can find that tie in here and what we can learn from them.
     
  10. May 13, 2008 #9

    marcus

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    Giddings is the String thinker in the lineup. Here is the recent paper of his that matches the topic:
    http://arxiv.org/abs/0705.2197
    Black holes, information, and locality
    Steven B. Giddings
    (last revised 5 Feb 2008)

    "Thirty years of a deepening information paradox suggest the need to revise our basic physical framework. Multiple indicators point toward reassessment of the principle of locality: lack of a precise definition in quantum gravity, behavior of high-energy scattering, hints from strings and AdS/CFT, conundrums of quantum cosmology, and finally lack of good alternative resolutions of the paradox. A plausible conjecture states that the non-perturbative dynamics of gravity is unitary but nonlocal. String theory may directly address these issues but so far important aspects remain elusive. If this viewpoint is correct, critical questions are to understand the 'correspondence' limit where nonlocal physics reduces to local quantum field theory, and beyond, to unveil principles of an underlying nonlocal theory."
    =============================

    Loll mentioned that when they integrate what is essentially a Feynman path integral thru the space of geometries, they get de Sitter space. That is, a maximally symmetric spacetime with positive cosmological constant. This corresponds to a recent paper:

    http://arxiv.org/abs/0712.2485
    Planckian Birth of the Quantum de Sitter Universe
    Authors: J. Ambjorn, A. Gorlich, J. Jurkiewicz, R. Loll
    4 pages, 3 figures
    (Submitted on 17 Dec 2007)

    "We show that the quantum universe emerging from a nonperturbative, Lorentzian sum-over-geometries can be described with high accuracy by a four-dimensional de Sitter spacetime. By a scaling analysis involving Newton's constant, we establish that the linear size of the quantum universes under study is in between 17 and 28 Planck lengths. Somewhat surprisingly, the measured quantum fluctuations around the de Sitter universe in this regime are to good approximation still describable semiclassically. The numerical evidence presented comes from a regularization of quantum gravity in terms of causal dynamical triangulations."
    ==========================

    I think I will discuss some of the physics in THIS paper, as a sample of what will be highlighted at Oporto this summer. That seems like one way to learn something from the Oporto Meeting's program, or to let it teach us something. If anyone else wants to discuss some of the other content, that's fine too.
     
  11. May 15, 2008 #10

    marcus

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    Strings '08 speaker list

    Strings '08 will be at CERN August 18-23
    The speaker list is here:
    http://ph-dep-th.web.cern.ch/ph-dep-th/content2/workshops/strings2008/?site=content/talks.html
    All the talks are plenary session and all speakers are invited (there are no parallel sessions with volunteered talks).
    There are 8 one-hour summary overview talks listed and about 30 half-hour research talks. It is an unusually compact format, for what is usually a large well-attended conference.
    Here is what the welcome page at the webite has to say:
    "Welcome to Strings 2008, which will be held at CERN in the year during which the LHC starts up. ... For more details about the conference, see the links on the left.

    The lectures will take place in the CERN main auditorium. All participants must register in order to get admitted to the lecture hall. There will be about 40 talks, most of which are summaries of 30 minutes each, but each day there will also be one or two more comprehensive, one hour review talks. The speakers will be nominated by the committee, and self-applications are discouraged. The precise schedule will be announced on this web site shortly before the meeting. "
     
    Last edited: May 15, 2008
  12. May 21, 2008 #11

    marcus

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    Emergent gravity at MIT in August

    http://www.rle.mit.edu/emergent/participants.htm

    a gathering of new approaches we've been hearing a lot about.
    celebrity list includes

    Renate Loll
    Xiao-gang Wen
    Lee Smolin
    Seth Lloyd
    Song He (the guy at Beijing working on braid-matter with Yidun Wan at Perimeter)

    25-29 August, at the MIT Center for Theoretical Physics, registration is free
     
    Last edited: May 21, 2008
  13. May 29, 2008 #12

    marcus

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    Congratulations Francesca!

    PF member Francesca is in Rovelli's group at Marseille. The homogeneity assumption needs to be relaxed in LQC, to bring LQC closer to the full LQG theory. They found a way to do it partway in a gradual fashion. Recently Rovelli delivered an online seminar talk about this at ILQGS.

    http://arxiv.org/abs/0805.4585
    Stepping out of Homogeneity in Loop Quantum Cosmology
    Carlo Rovelli, Francesca Vidotto
    16 pages
    (Submitted on 29 May 2008)

    "We explore the extension of quantum cosmology outside the homogeneous approximation, using the formalism of loop quantum gravity..."
     
  14. Jun 29, 2008 #13

    marcus

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    QG school and workshop at Sussex in September

    The main event is a 3-day workshop 17-19 September 2008
    http://www.ippp.dur.ac.uk/Workshops/08/CLAQG
    This will be held at Sussex and admission is free. It will be preceded by a 2-day school
    15-16 September aimed at getting graduate students and postdocs entering the field prepared with the basics so they can get maximum benefit from the workshop.
    http://www.ippp.dur.ac.uk/Workshops/08/NPMQFT

    The workshop is called
    Workshop on Continuum and Lattice Approaches to Quantum Gravity (CLAQG)
    and the main speakers will be

    * Jan Ambjorn (NBI Copenhagen)
    * Damiano Anselmi (U Pisa)
    * Emil Bjerrum-Bohr (IAS Princeton)
    * Daniel Litim (U Sussex)
    * Renate Loll (U Utrecht)
    * Max Niedermaier (U Tours)
    * Roberto Percacci (SISSA Trieste)
    * Martin Reuter (U Mainz)
    * Thomas Thiemann (AEI Golm and Perimeter Institute)

    It is noteworthy that TRIANGULATIONS or lattice QG and also ASYMPTOTIC SAFETY QG are each represented by several speakers. Jan Ambjorn and Renate Loll are both speaking about the triangulations work. Roberto Percacci, Max Niedermaier, and Martin Reuter, pursuing the asymptotic safety approach, are there as well.

    In both these two approaches they find that the quantum spacetime continuum does not have a fixed dimensionality, but that a 4D smooth continuum emerges at larger scale while at smaller (trans-Planck) scale the dimension goes down and the spacetime is rougher.

    The two approaches are in a sense natural allies because they confirm each other. They find similar mathematical reality coming from different directions. This mutual support has been made explicit in numerous papers and at last years Loops 07 conference.

    It looks to me as if this Sussex school and workshop is in effect recruiting brainpower into the field. There is a lot of work to be done in this field and they can use a lot of grad students and postdocs.

    The two-day preparatory school before the workshop is called
    School on Non-Perturbative Methods in Quantum Field Theory (NPMQFT)

    * Basics of the non-perturbative renormalisation group (D. Litim, U Sussex)
    * Basics of the RG for QCD and confinement (J.M. Pawlowski, U Heidelberg)
    * Basics of QCD on the lattice (O. Philipsen, U Muenster)
    * Basics of asymptotic safety for gravity (M. Niedermaier, U Tours)
    * Basics of the RG for quantum gravity (M. Reuter, U Mainz)
    * Basics of lattice quantum gravity I (R. Loll, U Utrecht)
    * Basics of lattice quantum gravity II (J. Barrett, U Nottingham) (t.b.c.)

    School starts 9AM Monday morning 15 September and Workshop ends 6PM Friday evening 19 September.
    Notice that the participation of John Barrett is "to be confirmed".
    Notice that Renate Loll is calling the causal dynamical triangulations (CDT) approach by the name "lattice quantum gravity".
    This has the acronym LQG causing a mildly stimulating subliminal shock. In a nonperturbative lattice approach to spacetime geometry, the lattice is not a fixed regular lattice, but is, in effect, a random dynamical triangulation. Evidently one can call triangulation QG by the name lattice QG but making clear that it is a nonperturbative and background independent approach.
    Anyway that is the list of topics to be covered in the school
     
    Last edited: Jun 29, 2008
  15. Jul 23, 2008 #14

    marcus

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    Re: Announcements

    The first week of September there will be something called
    INTERNATIONAL SCHOOL OF SUBNUCLEAR PHYSICS
    46th Course: Predicted and Totally Unexpected in the Energy Frontier Opened by LHC
    Directors: G. 't HOOFT – A. ZICHICHI
    29 August – 7 September 2008

    and the interesting thing---why I mention it, and ask if anyone has more information---is the quantum gravity angle. Apparently Renate Loll is lecturing at the school.
    Loll does simplicial quantum geometry. Her group at Utrecht is on a roll and has remarkable new results---the emergence of a smooth de Sitter universe from chaotic quantum ground, for example, estimates the size of quantum fluctuations in geometry at various scales.

    So how does that fit in with the theme of "Totally Unexpected at the LHC Frontier"?

    Here's a link
    http://www.ccsem.infn.it/
    Here's Loll's page mentioning the School of Subnuclear Physics in September at Erice, Sicily
    http://www.phys.uu.nl/~loll/Web/seminars/seminars.html

    Wow! I just saw the poster for the school. It is worth downloading. You can get it from the ccsem link I just gave by clicking on posters and selecting the Subnuclear Physics one.
    The poster has a list of lectures on hot theory topics.
    't Hooft on Crystalline Gravity
    Lee Smolin on Loop Quantum Gravity
    John Schwarz on Superstring/M
    Renate Loll on Dynamical Triangulations Gravity
    S. Ferrara on SUSY
    Z. Bern on SUGRA

    It is pretty select blue chip company. Leonard Susskind was invited but not to lecture (they already have Superstring represented by John Schwarz). The line-up gives an up-to-date perspective on what the organizers consider hot theory topics as we approach LHC startup.

    Besides the theory lectures, they have talks by experimentalists on projected signals at LHC. It looks like it'll be a grand school! Maybe some people we know will be able to attend. Part of the stated aim of the Erice school is to encourage and inspire young physicists so they appear to have places and support for a substantial number. We'll see.
     
    Last edited: Jul 23, 2008
  16. Jul 23, 2008 #15

    marcus

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  17. Jul 27, 2008 #16

    MTd2

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  18. Aug 7, 2008 #17

    marcus

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    Re: John's nice exposion o Loll's gravity on his blog!

    MTd2, thanks for posting this. The conversation at n-category cafe is quite interesting. I think a letter may be missing from your link. I couldn't get it to work but this works for me:
    http://golem.ph.utexas.edu/category/2008/07/causality_in_discrete_models_o.html
     
  19. Sep 15, 2008 #18
  20. Oct 21, 2008 #19

    MTd2

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    Re: Announcements

    Garrett will organize a small workshop.
     
  21. Dec 2, 2008 #20

    marcus

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    Re: Announcements

    Strings 2009 conference will be held in Rome, 22-26 July
    http://strings2009.roma2.infn.it/home.html
    The plan is all the talks will be invited plenary. There will be no contributed talks in parallel sessions. This is the same plan as was followed by Strings 2008 at CERN in August.
     
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