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Our picks for fourth quarter 2013 MIP (most important QG paper)

  1. On How Neutrino Protects the Axion

    12.5%
  2. Structural aspects of loop quantum gravity and loop quantum cosmology from an algebraic perspective

    12.5%
  3. Hawking radiation from a spherical loop quantum gravity black hole

    25.0%
  4. General Relativity from a Thermodynamic Perspective

    75.0%
  5. Gravitational Energy, Local Holography and Non-equilibrium Thermodynamics

    25.0%
  6. Quantum group spin nets: refinement limit and relation to spin foams

    0 vote(s)
    0.0%
  7. Time evolution as refining, coarse graining and entangling

    25.0%
  8. The Koslowski-Sahlmann representation: Gauge and diffeomorphism invariance

    0 vote(s)
    0.0%
  9. Note on the super inflation in loop quantum cosmology

    0 vote(s)
    0.0%
  10. Null twisted geometries

    0 vote(s)
    0.0%
  11. Matter matters in asymptotically safe quantum gravity

    12.5%
  12. Twistor relative locality

    25.0%
  13. Relative information at the foundation of physics

    25.0%
  14. Group field theory as the 2nd quantization of Loop Quantum Gravity

    37.5%
  15. Quantization ambiguities and bounds on geometric scalars in anisotropic loop quantum cosmology

    12.5%
  16. A Gravitational Origin of the Arrows of Time

    25.0%
  17. Deformation Operators of Spin Networks and Coarse-Graining

    12.5%
  18. Radiative corrections to the EPRL-FK spinfoam graviton

    25.0%
  19. Cosmological perturbations in teleparallel Loop Quantum Cosmology

    12.5%
  20. Quantum gravity from the point of view of locally covariant quantum field theory

    25.0%
Multiple votes are allowed.
  1. Dec 31, 2013 #1

    marcus

    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    Of the twenty candidates, indicate the ones you think will prove most significant for future QG research. I've included two papers from earlier in the year which I mistakenly overlooked when they first appeared. Since the poll is multiple choice, it's possible to vote for several papers. Abstracts follow in the next post.

    http://arxiv.org/abs/1312.7273
    On How Neutrino Protects the Axion
    Gia Dvali, Sarah Folkerts, Andre Franca
    (Submitted on 27 Dec 2013)
    9 pages

    http://arxiv.org/abs/1312.3657
    Structural aspects of loop quantum gravity and loop quantum cosmology from an algebraic perspective
    Alexander Stottmeister, Thomas Thiemann
    (Submitted on 12 Dec 2013)
    45 pages

    http://arxiv.org/abs/1312.3595
    Hawking radiation from a spherical loop quantum gravity black hole
    Rodolfo Gambini, Jorge Pullin
    (Submitted on 12 Dec 2013)
    13 pages

    http://arxiv.org/abs/1312.3253
    General Relativity from a Thermodynamic Perspective
    Thanu Padmanabhan
    (Submitted on 11 Dec 2013)
    53 pages

    http://arxiv.org/abs/1312.1538
    Gravitational Energy, Local Holography and Non-equilibrium Thermodynamics
    Laurent Freidel
    (Submitted on 5 Dec 2013)
    41 pages, 3 figures

    http://arxiv.org/abs/arXiv:1312.0905
    Quantum group spin nets: refinement limit and relation to spin foams
    Bianca Dittrich, Mercedes Martin-Benito, Sebastian Steinhaus
    (Submitted on 3 Dec 2013)
    30+5 pages, many figures

    http://arxiv.org/abs/1311.7565
    Time evolution as refining, coarse graining and entangling
    Bianca Dittrich, Sebastian Steinhaus
    (Submitted on 29 Nov 2013)
    33 pages, 9 figures

    http://arxiv.org/abs/arXiv:1311.6117
    The Koslowski-Sahlmann representation: Gauge and diffeomorphism invariance
    Miguel Campiglia, Madhavan Varadarajan
    (Submitted on 24 Nov 2013)
    45 pages.

    http://arxiv.org/abs/1311.5325
    Note on the super inflation in loop quantum cosmology
    Kui Xiao, Xiao-Kai He, Jian-Yang Zhu
    (Submitted on 21 Nov 2013)
    9 pages, 4 figures. Physics Letters B

    http://arxiv.org/abs/1311.3279
    Null twisted geometries
    Simone Speziale, Mingyi Zhang
    (Submitted on 13 Nov 2013)
    22 pages, 3 figures

    http://arxiv.org/abs/1311.2898
    Matter matters in asymptotically safe quantum gravity
    Pietro Donà, Astrid Eichhorn, Roberto Percacci
    (Submitted on 12 Nov 2013)
    22 pages, 18 figures, 4 tables

    http://arxiv.org/abs/1311.0186
    Twistor relative locality
    Lee Smolin
    (Submitted on 1 Nov 2013)
    10 pages

    http://arxiv.org/abs/1311.0054
    Relative information at the foundation of physics
    Carlo Rovelli
    (Submitted on 31 Oct 2013)
    3 pages. Second prize in the 2013 FQXi contest "It From Bit or Bit From It?"

    http://arxiv.org/abs/1310.7786
    Group field theory as the 2nd quantization of Loop Quantum Gravity
    Daniele Oriti
    (Submitted on 29 Oct 2013)
    23 pages, 5 figures

    http://arxiv.org/abs/1310.6728
    Quantization ambiguities and bounds on geometric scalars in anisotropic loop quantum cosmology
    Parampreet Singh, Edward Wilson-Ewing
    (Submitted on 24 Oct 2013)
    34 pages

    http://arxiv.org/abs/1310.5167
    A Gravitational Origin of the Arrows of Time
    Julian Barbour, Tim Koslowski, Flavio Mercati
    (Submitted on 18 Oct 2013)
    44+14 pages, 8 figures, 1 table

    http://arxiv.org/abs/1310.3362
    Deformation Operators of Spin Networks and Coarse-Graining
    Etera R. Livine
    (Submitted on 12 Oct 2013)
    24 pages

    http://arxiv.org/abs/1310.2174
    Radiative corrections to the EPRL-FK spinfoam graviton
    Aldo Riello
    (Submitted on 8 Oct 2013)
    13 pages, 4 figures

    http://arxiv.org/abs/arXiv:1309.0352
    Cosmological perturbations in teleparallel Loop Quantum Cosmology
    Jaime Haro
    (Submitted on 2 Sep 2013)
    18 pages. Journal of Cosmology and Astroparticle Physics

    http://arxiv.org/abs/1306.1058
    Quantum gravity from the point of view of locally covariant quantum field theory
    Romeo Brunetti, Klaus Fredenhagen, Katarzyna Rejzner
    (Submitted on 5 Jun 2013)
    51 pages
     
  2. jcsd
  3. Dec 31, 2013 #2

    marcus

    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    This quarter's poll includes several alternates to and new variants of Loop gravity: work bridging between nonperturbative QG and particle theory, also at the bottom of the list a throwback to perturbative QG that is still background independent (!), then there's a derivation of "arrow of time" from Shape, the K-S variant of Loop, a Teleparallel hybrid with Loop, matter in Asymptotic Safe QG, and Hawking radiation from the Loop black hole. Basically this time the poll includes a lot of crossing of specialty lines.

    http://arxiv.org/abs/1312.7273
    On How Neutrino Protects the Axion
    Gia Dvali, Sarah Folkerts, Andre Franca
    (Submitted on 27 Dec 2013)
    We show how the neutrino can sacrifice itself to quantum gravity and save the axion solution to the strong-CP problem. This mechanism puts an upper bound on the lightest neutrino mass.
    9 pages

    http://arxiv.org/abs/1312.3657
    Structural aspects of loop quantum gravity and loop quantum cosmology from an algebraic perspective
    Alexander Stottmeister, Thomas Thiemann
    (Submitted on 12 Dec 2013)
    We comment on structural properties of the algebras ALQG/LQC underlying loop quantum gravity and loop quantum cosmology, especially the representation theory, relating the appearance of the (dynamically induced) superselection structure (θ-sectors) in loop quantum cosmology to recently proposed representations with non-degenerate background geometries in loop quantum gravity with Abelian structure group. To this end, we review and employ the concept of extending a given (observable) algebra with possibly non-trivial centre to a (charged) field algebra with (global) gauge group.We also interpret the results in terms of the geometry of the structure group G. Furthermore, we analyze the Koslowski-Sahlmann representations with non-degenerate background in the case of a non-Abelian structure group. We find that these representations can be interpreted from two different, though related, points view: Either, the standard algebras of loop quantum gravity need to be extended by a (possibly) central term, or the elementary flux vector fields need to acquire a shift related to the (classical) background to make these representations well-defined. Both perspectives are linked by the fact that the background shift is not an automorphism of the algebras, but rather an affine transformation. Finally, we show how similar algebraic mechanisms, which are used to explain the breaking of chiral symmetry and the occurrence of θ-vacua in quantum field theory, extend to loop quantum gravity. Thus, opening a path for the discussion of these questions in loop quantum gravity.
    45 pages

    http://arxiv.org/abs/1312.3595
    Hawking radiation from a spherical loop quantum gravity black hole
    Rodolfo Gambini, Jorge Pullin
    (Submitted on 12 Dec 2013)
    We introduce quantum field theory on quantum space-times techniques to characterize the quantum vacua as a first step towards studying black hole evaporation in spherical symmetry in loop quantum gravity and compute the Hawking radiation. We use as quantum space time the recently introduced exact solution of the quantum Einstein equations in vacuum with spherical symmetry and consider a spherically symmetric test scalar field propagating on it. The use of loop quantum gravity techniques in the background space-time naturally regularizes the matter content, solving one of the main obstacles to back reaction calculations in more traditional treatments. The discreteness of area leads to modifications of the quantum vacua, eliminating the trans-Planckian modes close to the horizon, which in turn eliminates all singularities from physical quantities, like the expectation value of the stress energy tensor. Apart from this, the Boulware, Hartle--Hawking and Unruh vacua differ little from the treatment on a classical space-time. The asymptotic modes near scri are reproduced very well. We show that the Hawking radiation can be computed, leading to an expression similar to the conventional one but with a high frequency cutoff. Since many of the conclusions concern asymptotic behavior, where the spherical mode of the field behaves in a similar way as higher multipole modes do, the results can be readily generalized to non spherically symmetric fields.
    13 pages

    http://arxiv.org/abs/1312.3253
    General Relativity from a Thermodynamic Perspective
    Thanu Padmanabhan
    (Submitted on 11 Dec 2013)
    Several recent results suggest that gravity is an emergent phenomenon with its field equations having the same status as, say, the equations of fluid dynamics. I describe several additional results, supporting this paradigm and connecting the gravitational dynamics in a bulk region of space with a thermodynamic description in the boundary of that region:
    (1) The Noether charge contained in a bulk region, associated with a specific time evolution vector field, has a direct thermodynamic interpretation as the gravitational heat content of the boundary surface.
    (2) This result, in turn, shows that all static spacetimes maintain holographic equipartition; in these spacetimes, the number of degrees of freedom in the boundary is equal to the number of degrees of freedom in the bulk.
    (3) In a general, evolving spacetime, the rate of change of gravitational momentum is related to the difference between the number of bulk and boundary degrees of freedom. It is this departure from the holographic equipartition which drives the time evolution of the spacetime.
    (4) When the equations of motion hold, the (naturally defined) total energy of the gravity plus matter within a bulk region, will be equal to the boundary heat content.
    (5) After motivating the need for an alternate description of gravity (if we have to solve the cosmological constant problem), I describe a thermodynamic variational principle based on null surfaces to achieve this goal. The concept of gravitational heat density of the null surfaces arises naturally from the Noether charge associated with the null congruence. The null surface variational principle, in fact, extremises the total heat content of the matter plus gravity system. Several variations on this theme and implications are described.
    53 pages

    http://arxiv.org/abs/1312.1538
    Gravitational Energy, Local Holography and Non-equilibrium Thermodynamics
    Laurent Freidel
    (Submitted on 5 Dec 2013)
    We study the properties of gravitational system in finite regions bounded by gravitational screens. We present the detail construction of the total energy of such regions and of the energy and momentum balance equations due to the flow of matter and gravitational radiation through the screen. We establish that the gravitational screen possesses analogs of surface tension, internal energy and viscous stress tensor, while the conservations are analogs of non-equilibrium balance equations for a viscous system. This gives a precise correspondence between gravity in finite regions and non-equilibrium thermodynamics.
    41 pages, 3 figures

    http://arxiv.org/abs/arXiv:1312.0905
    Quantum group spin nets: refinement limit and relation to spin foams
    Bianca Dittrich, Mercedes Martin-Benito, Sebastian Steinhaus
    (Submitted on 3 Dec 2013)
    So far spin foam models are hardly understood beyond a few of their basic building blocks. To make progress on this question, we define analogue spin foam models, so called spin nets, for quantum groups SU(2)k and examine their effective continuum dynamics via tensor network renormalization. In the refinement limit of this coarse graining procedure, we find a vast non-trivial fixed point structure beyond the degenerate and the BF phase. In comparison to previous work, we use fixed point intertwiners, inspired by Reisenberger's construction principle [1] and the recent work [2], as the initial parametrization. In this new parametrization fine tuning is not required in order to flow to these new fixed points. Encouragingly, each fixed point has an associated extended phase, which allows for the study of phase transitions in the future. Finally we also present an interpretation of spin nets in terms of melonic spin foams. The coarse graining flow of spin nets can thus be interpreted as describing the effective coupling between two spin foam vertices or space time atoms.
    30+5 pages, many figures

    http://arxiv.org/abs/1311.7565
    Time evolution as refining, coarse graining and entangling
    Bianca Dittrich, Sebastian Steinhaus
    (Submitted on 29 Nov 2013)
    We argue that refining, coarse graining and entangling operators can be obtained from time evolution operators. This applies in particular to geometric theories, such as spin foams. We point out that this provides a construction principle for the physical vacuum in quantum gravity theories and more generally allows to construct a (cylindrically) consistent continuum limit of the theory.
    33 pages, 9 figures

    http://arxiv.org/abs/arXiv:1311.6117
    The Koslowski-Sahlmann representation: Gauge and diffeomorphism invariance
    Miguel Campiglia, Madhavan Varadarajan
    (Submitted on 24 Nov 2013)
    The discrete spatial geometry underlying Loop Quantum Gravity (LQG) is degenerate almost everywhere. This is at apparent odds with the non-degeneracy of asymptotically flat metrics near spatial infinity. Koslowski generalised the LQG representation so as to describe states labelled by smooth non-degenerate triad fields. His representation was further studied by Sahlmann with a view to imposing gauge and spatial diffeomorphism invariance through group averaging methods. Motivated by the desire to model asymptotically flat quantum geometry by states with triad labels which are non-degenerate at infinity but not necessarily so in the interior, we initiate a generalisation of Sahlmann's considerations to triads of varying degeneracy. In doing so, we include delicate phase contributions to the averaging procedure which are crucial for the correct implementation of the gauge and diffeomorphism constraints, and whose existence can be traced to the background exponential functions recently constructed by one of us. Our treatment emphasizes the role of symmetries of quantum states in the averaging procedure. Semianalyticity, influential in the proofs of the beautiful uniqueness results for LQG, plays a key role in our considerations. As a by product, we re-derive the group averaging map for standard LQG, highlighting the role of state symmetries and explicitly exhibiting the essential uniqueness of its specification.
    45 pages.

    http://arxiv.org/abs/1311.5325
    Note on the super inflation in loop quantum cosmology
    Kui Xiao, Xiao-Kai He, Jian-Yang Zhu
    (Submitted on 21 Nov 2013)
    Phenomenological effect of the super-inflation in loop quantum cosmology (LQC) is discussed. We investigate the case that the Universe is filled with the interacting field between massive scalar field and radiation. Considering the damping coefficient Γ as a constant, the changes of the scale factor during super-inflation with four different initial conditions are discussed, and we find that the changes of the scale factor depend on the initial values of energy density of the scalar field and radiation at the bounce point. But no matter which initial condition is chosen, the radiation always dominated at the late time. Moreover, we investigate whether the super-inflation can provide enough e-folding number. For the super-inflation starts from the quantum bounce point, the initial value of Hubble parameter H(ti)∼0, then it is possible to solve the flatness problem and horizon problem. As an example, following the method of Amoros to calculate particle horizon on the condition that the radiation dominated at bounce point, we find that the Universe has had enough time to be homogeneous and isotopic.
    9 pages, 4 figures. Physics Letters B

    http://arxiv.org/abs/1311.3279
    Null twisted geometries
    Simone Speziale, Mingyi Zhang
    (Submitted on 13 Nov 2013)
    We define and investigate a quantisation of null hypersurfaces in the context of loop quantum gravity on a fixed graph. The main tool we use is the parametrisation of the theory in terms of twistors, which has already proved useful in discussing the interpretation of spin networks as the quantization of twisted geometries. The classical formalism can be extended in a natural way to null hypersurfaces, with the Euclidean polyhedra replaced by null polyhedra with space-like faces, and SU(2) by the little group ISO(2). The main difference is that the simplicity constraints present in the formalism are all first class, and the symplectic reduction selects only the helicity subgroup of the little group. As a consequence, information on the shapes of the polyhedra is lost, and the result is a much simpler, abelian geometric picture. It can be described by an Euclidean singular structure on the 2-dimensional space-like surface defined by a foliation of space-time by null hypersurfaces. This geometric structure is naturally decomposed into a conformal metric and scale factors, forming locally conjugate pairs. Proper action-angle variables on the gauge-invariant phase space are described by the eigenvectors of the Laplacian of the dual graph. We also identify the variables of the phase space amenable to characterize the extrinsic geometry of the foliation. Finally, we quantise the phase space and its algebra using Dirac's algorithm, obtaining a notion of spin networks for null hypersurfaces. Such spin networks are labelled by SO(2) quantum numbers, and are embedded non-trivially in the unitary, infinite-dimensional irreducible representations of the Lorentz group.
    22 pages, 3 figures

    http://arxiv.org/abs/1311.2898
    Matter matters in asymptotically safe quantum gravity
    Pietro Donà, Astrid Eichhorn, Roberto Percacci
    (Submitted on 12 Nov 2013)
    We investigate the compatibility of minimally coupled scalar, fermion and gauge fields with asymptotically safe quantum gravity, using nonperturbative functional Renormalization Group methods. We study d=4,5 and 6 dimensions and within certain approximations find that for a given number of gauge fields there is a maximal number of scalar and fermion degrees of freedom compatible with an interacting fixed point at positive Newton coupling. The bounds impose severe constraints on grand unification with fundamental Higgs scalars. Supersymmetry and universal extra dimensions are also generally disfavored. The standard model and its extensions accommodating right-handed neutrinos, the axion and dark-matter models with a single scalar are compatible with a fixed point.
    22 pages, 18 figures, 4 tables

    http://arxiv.org/abs/1311.0186
    Twistor relative locality
    Lee Smolin
    (Submitted on 1 Nov 2013)
    We present a version of relative locality based on the geometry of twistor space. This can also be thought of as a new kind of deformation of twistor theory based on the construction of a bundle of twistor spaces over momentum space. Locality in space-time is emergent and is deformed in a precise way when a connection on that bundle is non-flat. This gives a precise and controlled meaning to Penrose's hypothesis that quantum gravity effects will deform twistor space in such a way as to maintain causality and relativistic invariance while weakening the notion that interactions take place at points in spacetime.
    10 pages

    http://arxiv.org/abs/1311.0054
    Relative information at the foundation of physics
    Carlo Rovelli
    (Submitted on 31 Oct 2013)
    Shannon's notion of relative information between two physical systems can function as foundation for statistical mechanics and quantum mechanics, without referring to subjectivism or idealism. It can also represent a key missing element in the foundation of the naturalistic picture of the world, providing the conceptual tool for dealing with its apparent limitations. I comment on the relation between these ideas and Democritus.
    3 pages. Second prize in the 2013 FQXi contest "It From Bit or Bit From It?"

    http://arxiv.org/abs/1310.7786
    Group field theory as the 2nd quantization of Loop Quantum Gravity
    Daniele Oriti
    (Submitted on 29 Oct 2013)
    We construct a 2nd quantized reformulation of canonical Loop Quantum Gravity at both kinematical and dynamical level, in terms of a Fock space of spin networks, and show in full generality that it leads directly to the Group Field Theory formalism. In particular, we show the correspondence between canonical LQG dynamics and GFT dynamics leading to a specific GFT model from any definition of quantum canonical dynamics of spin networks. We exemplify the correspondence of dynamics in the specific example of 3d quantum gravity. The correspondence between canonical LQG and covariant spin foam models is obtained via the GFT definition of the latter.
    23 pages, 5 figures

    http://arxiv.org/abs/1310.6728
    Quantization ambiguities and bounds on geometric scalars in anisotropic loop quantum cosmology
    Parampreet Singh, Edward Wilson-Ewing
    (Submitted on 24 Oct 2013)
    We study quantization ambiguities in loop quantum cosmology that arise for space-times with non-zero spatial curvature and anisotropies. Motivated by lessons from different possible loop quantizations of the closed Friedmann-Lemaitre-Robertson-Walker cosmology, we find that using open holonomies of the extrinsic curvature, which due to gauge-fixing can be treated as a connection, leads to the same quantum geometry effects that are found in spatially flat cosmologies. More specifically, in contrast to the quantization based on open holonomies of the Ashtekar-Barbero connection, the expansion and shear scalars in the effective theories of the Bianchi type II and Bianchi type IX models have upper bounds, and these are in exact agreement with the bounds found in the effective theories of the Friedmann-Lemaitre-Robertson-Walker and Bianchi type I models in loop quantum cosmology. We also comment on some ambiguities present in the definition of inverse triad operators and their role.
    34 pages

    http://arxiv.org/abs/1310.5167
    A Gravitational Origin of the Arrows of Time
    Julian Barbour, Tim Koslowski, Flavio Mercati
    (Submitted on 18 Oct 2013)
    The only widely accepted explanation for the various arrows of time that everywhere and at all epochs point in the same direction is the 'past hypothesis': the Universe had a very special low-entropy initial state. We present the first evidence for an alternative conjecture: the arrows exist in all solutions of the gravitational law that governs the Universe and arise because the space of its true degrees of freedom (shape space) is asymmetric. We prove our conjecture for arrows of complexity and information in the Newtonian N-body problem. Except for a set of measure zero, all of its solutions for non-negative energy divide at a uniquely defined point into two halves. In each a well-defined measure of complexity fluctuates but grows irreversibly between rising bounds from that point. Structures that store dynamical information are created as the complexity grows. Recognition of the division is a key novelty of our approach. Each solution can be viewed as having a single past and two distinct futures emerging from it. Any internal observer must be in one half of the solution and will only be aware of one past and one future. The 'paradox' of a time-symmetric law that leads to observationally irreversible behaviour is fully resolved. General Relativity shares enough architectonic structure with the N-body problem for us to prove the existence of analogous complexity arrows in the vacuum Bianchi IX model. In the absence of non-trivial solutions with matter we cannot prove that arrows of dynamical information will arise in GR, though they have in our Universe. Finally, we indicate how the other arrows of time could arise.
    44+14 pages, 8 figures, 1 table

    http://arxiv.org/abs/1310.3362
    Deformation Operators of Spin Networks and Coarse-Graining
    Etera R. Livine
    (Submitted on 12 Oct 2013)
    In the context of loop quantum gravity, quantum states of geometry are mathematically defined as spin networks living on graphs embedded in the canonical space-like hypersurface. In the effort to study the renormalisation flow of loop gravity, a necessary step is to understand the coarse-graining of these states in order to describe their relevant structure at various scales. Using the spinor network formalism to describe the phase space of loop gravity on a given graph, we focus on a bounded (connected) region of the graph and coarse-grain it to a single vertex using a gauge-fixing procedure. We discuss the ambiguities in the gauge-fixing procedure and their consequences for coarse-graining spin(or) networks. This allows to define the boundary deformations of that region in a gauge-invariant fashion and to identify the area preserving deformations as U(N) transformations similarly to the already well-studied case of a single intertwiner. The novelty is that the closure constraint is now relaxed and the closure defect interpreted as a local measure of the curvature inside the coarse-grained region. It is nevertheless possible to cancel the closure defect by a Lorentz boost. We further identify a Lorentz-invariant observable related to the area and closure defect, which we name "rest area". Its physical meaning remains an open issue.
    24 pages

    http://arxiv.org/abs/1310.2174
    Radiative corrections to the EPRL-FK spinfoam graviton
    Aldo Riello
    (Submitted on 8 Oct 2013)
    I study the corrections engendered by the insertion of a "melon" graph in the bulk of the first-order spinfoam used for the graviton propagator. I find that these corrections are highly non-trivial and, in particular, that they concern those terms which disappear in the Bojowald-Bianchi-Magliaro-Perini limit of vanishing Barbero-Immirzi parameter at fixed area. This fact is the first realization of the often cited idea that the spinfoam amplitude receives higher order corrections under the refinement of the underlying two-complex.
    13 pages, 4 figures

    http://arxiv.org/abs/arXiv:1309.0352
    Cosmological perturbations in teleparallel Loop Quantum Cosmology
    Jaime Haro
    (Submitted on 2 Sep 2013)
    Cosmological perturbations in Loop Quantum Cosmology (LQC) are usually studied incorporating either holonomy corrections, where the Ashtekar connection is replaced by a suitable sinus function in order to have a well-defined quantum analogue, or inverse-volume corrections coming from the eigenvalues of the inverse-volume operator.
    In this paper we will develop an alternative approach to calculate cosmological perturbations in LQC based on the fact that, holonomy corrected LQC in the flat Friedmann-Lemaître-Robertson-Walker (FLRW) geometry could be also obtained as a particular case of teleparallel F(T) gravity (teleparallel LQC). The main idea of our approach is to mix the simple bounce provided by holonomy corrections in LQC with the non-singular perturbation equations given by F(T) gravity, in order to obtain a matter bounce scenario as a viable alternative to slow-roll inflation.
    In our study, we have obtained an scale invariant power spectrum of cosmological perturbations. However, the ratio of tensor to scalar perturbations is of order 1, which does not agree with the current observations. For this reason, we suggest a model where a transition from the matter domination to a quasi de Sitter phase is produced in order to enhance the scalar power spectrum.
    18 pages. Journal of Cosmology and Astroparticle Physics

    http://arxiv.org/abs/1306.1058
    Quantum gravity from the point of view of locally covariant quantum field theory
    Romeo Brunetti, Klaus Fredenhagen, Katarzyna Rejzner
    (Submitted on 5 Jun 2013)
    We construct perturbative quantum gravity in a generally covariant way. In particular our construction is background independent. It is based on the locally covariant approach to quantum field theory and the renormalized Batalin-Vilkovisky formalism. We do not touch the problem of nonrenormalizability and interpret the theory as an effective theory at large length scales.
    51 pages
     
    Last edited: Dec 31, 2013
  4. Jan 14, 2014 #3

    marcus

    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    Thanks to Nonlinearity, Chronos, and Jason_0 for getting the poll started! The ILQGS schedule of online talks has been posted for the Spring 2014 semester and I see that in just one week from today Pietro Dona will be giving a talk on one of the papers on our poll.
    Matter matters in asymptotically safe quantum gravity
    His co-authors on this paper were Roberto Percacci and Astrid Eichorn.
    Here's how the votes stack up on the poll so far.
    3 votes:
    http://arxiv.org/abs/1312.3253
    General Relativity from a Thermodynamic Perspective
    Thanu Padmanabhan
    (Submitted on 11 Dec 2013)
    53 pages

    2 votes:
    http://arxiv.org/abs/1312.3595
    Hawking radiation from a spherical loop quantum gravity black hole
    Rodolfo Gambini, Jorge Pullin
    (Submitted on 12 Dec 2013)
    13 pages

    http://arxiv.org/abs/1312.1538
    Gravitational Energy, Local Holography and Non-equilibrium Thermodynamics
    Laurent Freidel
    (Submitted on 5 Dec 2013)
    41 pages, 3 figures

    http://arxiv.org/abs/1311.0054
    Relative information at the foundation of physics
    Carlo Rovelli
    (Submitted on 31 Oct 2013)
    3 pages. Second prize in the 2013 FQXi contest "It From Bit or Bit From It?"

    http://arxiv.org/abs/1310.2174
    Radiative corrections to the EPRL-FK spinfoam graviton
    Aldo Riello
    (Submitted on 8 Oct 2013)
    13 pages, 4 figures

    1 vote:
    http://arxiv.org/abs/1312.7273
    On How Neutrino Protects the Axion
    Gia Dvali, Sarah Folkerts, Andre Franca
    (Submitted on 27 Dec 2013)
    9 pages

    http://arxiv.org/abs/1311.7565
    Time evolution as refining, coarse graining and entangling
    Bianca Dittrich, Sebastian Steinhaus
    (Submitted on 29 Nov 2013)
    33 pages, 9 figures

    http://arxiv.org/abs/1311.2898
    Matter matters in asymptotically safe quantum gravity
    Pietro Donà, Astrid Eichhorn, Roberto Percacci
    (Submitted on 12 Nov 2013)
    22 pages, 18 figures, 4 tables

    http://arxiv.org/abs/1311.0186
    Twistor relative locality
    Lee Smolin
    (Submitted on 1 Nov 2013)
    10 pages

    http://arxiv.org/abs/1310.7786
    Group field theory as the 2nd quantization of Loop Quantum Gravity
    Daniele Oriti
    (Submitted on 29 Oct 2013)
    23 pages, 5 figures

    http://arxiv.org/abs/1310.6728
    Quantization ambiguities and bounds on geometric scalars in anisotropic loop quantum cosmology
    Parampreet Singh, Edward Wilson-Ewing
    (Submitted on 24 Oct 2013)
    34 pages

    http://arxiv.org/abs/1310.5167
    A Gravitational Origin of the Arrows of Time
    Julian Barbour, Tim Koslowski, Flavio Mercati
    (Submitted on 18 Oct 2013)
    44+14 pages, 8 figures, 1 table

    http://arxiv.org/abs/1310.3362
    Deformation Operators of Spin Networks and Coarse-Graining
    Etera R. Livine
    (Submitted on 12 Oct 2013)
    24 pages

    http://arxiv.org/abs/arXiv:1309.0352
    Cosmological perturbations in teleparallel Loop Quantum Cosmology
    Jaime Haro
    (Submitted on 2 Sep 2013)
    18 pages. Journal of Cosmology and Astroparticle Physics

    http://arxiv.org/abs/1306.1058
    Quantum gravity from the point of view of locally covariant quantum field theory
    Romeo Brunetti, Klaus Fredenhagen, Katarzyna Rejzner
    (Submitted on 5 Jun 2013)
    51 pages

    Four of the other online ILQGS talks scheduled for this Spring's series will be given by authors whose work appears on the poll, namely Dittrich, Steinhaus, Freidel, and Pullin. So there will be a fair amount of overlap between the Seminar series and our poll.
     
    Last edited: Jan 14, 2014
  5. Feb 18, 2014 #4

    marcus

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    Now that we are more than half way through the first quarter of 2014, I should begin to assemble a slate of MIP candidates for the next poll. These are tentative nominees, and some are obviously major papers. I'll list them in reverse chronological order, latest first.

    http://arxiv.org/abs/1402.4138
    Near-Horizon Radiation and Self-Dual Loop Quantum Gravity
    Marc Geiller, Karim Noui
    (Ashtekar-type, self-dual variables making a comeback)

    http://arxiv.org/abs/arXiv:1402.3155
    Quantum Reduced Loop Gravity: Semiclassical limit
    Emanuele Alesci, Francesco Cianfrani
    (semiclassical limit)

    http://arxiv.org/abs/arXiv:1402.2084
    Black Hole Entropy in Loop Quantum Gravity, Analytic Continuation, and Dual Holography
    Muxin Han
    (Ashtekar-type, self-dual variables making a comeback)

    http://arxiv.org/abs/arXiv:1402.1038
    A note on entanglement entropy and quantum geometry
    Norbert Bodendorfer
    (entanglement entropy=the other kind)

    http://arxiv.org/abs/1401.7731
    Quantization of systems with temporally varying discretization II: Local evolution moves
    http://arxiv.org/abs/1401.6062
    Quantization of systems with temporally varying discretization I: Evolving Hilbert spaces
    Philipp A Hoehn
    (part of Dittrich team's reformulation)

    http://arxiv.org/abs/1401.6562
    Planck stars
    Carlo Rovelli, Francesca Vidotto
    (slo-mo rebound BH)

    http://arxiv.org/abs/arXiv:1401.6441
    A new vacuum for Loop Quantum Gravity
    Bianca Dittrich, Marc Geiller
    (reformulation by a research team: incl. refinement, coarse-graining, classical limit)

    http://arxiv.org/abs/1401.5262
    Spacetime thermodynamics without hidden degrees of freedom
    Goffredo Chirco, Hal M. Haggard, Aldo Riello, Carlo Rovelli
    (GR recovered simply from thermodynamics of QG d.o.f.)

    http://arxiv.org/abs/1401.5083
    Non-Commutative Geometry, Non-Associative Geometry and the Standard Model of Particle Physics
    Latham Boyle, Shane Farnsworth
    (carrying Alain Connes Standard Model a step further)

    http://arxiv.org/abs/1401.4452
    Black holes within Asymptotic Safety
    Benjamin Koch, Frank Saueressig
    (asym. safe. BH)

    http://arxiv.org/abs/1401.4275
    Strict Deformation Quantisation of the G-connections via Lie Groupoid
    Alan Lai
    (C* quantization, another way to semiclassical limit?)

    http://arxiv.org/abs/arXiv:1401.0931
    Hamiltonian constraint in Euclidean LQG revisited: First hints of off-shell Closure
    Alok Laddha
    (problems with the Hamiltonian approach finally yielding)
     
    Last edited: Feb 19, 2014
  6. Feb 28, 2014 #5

    marcus

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    Chronos found and pointed out to us a couple of interesting papers about detection of a 3.5 keV X-ray emission line that could be a clue to a constituent of dark matter.
    DM could consist all or in part of 7 keV sterile neutrinos.
    Chronos has suggested (and I agree: it seems like a very good suggestion) that we include these papers on the next MIP poll.

    Admittedly they are not Loop-and-allied QG papers, traditionally the main focus of the poll. But because the make-up of DM is such a hot issue I would like (unless there is serious objection) to make an exception and include these two papers, at Chronos' urging.

    The two papers (Bulbul et al, and Boyarsky et al) could turn out to foreshadow the solution of a major problem in Cosmology, which would be very nice for several reasons.

    http://arxiv.org/abs/1402.2301
    Detection of An Unidentified Emission Line in the Stacked X-ray spectrum of Galaxy Clusters
    Esra Bulbul, Maxim Markevitch, Adam Foster, Randall K. Smith, Michael Loewenstein, Scott W. Randall
    (Submitted on 10 Feb 2014)
    We detect a weak unidentified emission line at E=(3.55-3.57)+/-0.03 keV in a stacked XMM spectrum of 73 galaxy clusters spanning a redshift range 0.01-0.35. MOS and PN observations independently show the presence of the line at consistent energies. When the full sample is divided into three subsamples (Perseus, Centaurus+Ophiuchus+Coma, and all others), the line is significantly detected in all three independent MOS spectra and the PN "all others" spectrum. It is also detected in the Chandra spectra of Perseus with the flux consistent with XMM (though it is not seen in Virgo). However, it is very weak and located within 50-110eV of several known faint lines, and so is subject to significant modeling uncertainties. On the origin of this line, we argue that there should be no atomic transitions in thermal plasma at this energy. An intriguing possibility is the decay of sterile neutrino, a long-sought dark matter particle candidate. Assuming that all dark matter is in sterile neutrinos with ms=2E=7.1 keV, our detection in the full sample corresponds to a neutrino decay mixing angle sin2(2θ)=7e-11, below the previous upper limits. …
    25 pages, 14 figures, submitted to ApJ

    http://arxiv.org/abs/1402.4119
    An unidentified line in X-ray spectra of the Andromeda galaxy and Perseus galaxy cluster
    Alexey Boyarsky, Oleg Ruchayskiy, Dmytro Iakubovskyi, Jeroen Franse
    (Submitted on 17 Feb 2014)
    We identify a weak line at E∼3.5 keV in X-ray spectra of the Andromeda galaxy and the Perseus galaxy cluster -- two dark matter-dominated objects, for which there exist deep exposures with the XMM-Newton X-ray observatory. Such a line was not previously known to be present in the spectra of galaxies or galaxy clusters. Although the line is weak, it has a clear tendency to become stronger towards the centers of the objects; it is stronger for the Perseus cluster than for the Andromeda galaxy and is absent in the spectrum of a very deep "blank sky" dataset. Although for individual objects it is hard to exclude the possibility that the feature is due to an instrumental effect or an atomic line of anomalous brightness, it is consistent with the behavior of a line originating from the decay of dark matter particles. Future detections or non-detections of this line in multiple astrophysical targets may help to reveal its nature.
    7 pages, 3 tables, 4 figures
     
    Last edited: Feb 28, 2014
  7. Mar 5, 2014 #6

    marcus

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    I'm beginning to assemble a slate of candidates for the next MIP poll which should go up around the end of March. These are some tentative nominees, listed in reverse chronological order, latest first. New additions are included with their abstracts:

    http://arxiv.org/abs/1402.6708
    A one-dimensional action for simplicial gravity in three dimensions
    Wolfgang M. Wieland
    (continuum limit in simplified case, model succeeds at recovering the Ponzano-Regge amplitudes.)

    http://arxiv.org/abs/1402.6613
    Numerical simulations of a loop quantum cosmos: robustness of the quantum bounce and the validity of effective dynamics
    Peter Diener, Brajesh Gupt, Parampreet Singh
    (further numerical confirmation of the bounce and of Loop cosmology's equation model)

    http://arxiv.org/abs/1402.4138
    Near-Horizon Radiation and Self-Dual Loop Quantum Gravity
    Marc Geiller, Karim Noui
    (Ashtekar-type, self-dual variables making a comeback)

    http://arxiv.org/abs/1402.4119
    An unidentified line in X-ray spectra of the Andromeda galaxy and Perseus galaxy cluster
    Alexey Boyarsky, Oleg Ruchayskiy, Dmytro Iakubovskyi, Jeroen Franse
    (possible dark matter particle?)

    http://arxiv.org/abs/arXiv:1402.3155
    Quantum Reduced Loop Gravity: Semiclassical limit
    Emanuele Alesci, Francesco Cianfrani
    (semiclassical limit)

    http://arxiv.org/abs/1402.2301
    Detection of An Unidentified Emission Line in the Stacked X-ray spectrum of Galaxy Clusters
    Esra Bulbul, Maxim Markevitch, Adam Foster, Randall K. Smith, Michael Loewenstein, Scott W. Randall
    (hint of dark matter particle)

    http://arxiv.org/abs/arXiv:1402.2084
    Black Hole Entropy in Loop Quantum Gravity, Analytic Continuation, and Dual Holography
    Muxin Han
    (Ashtekar-type, self-dual variables making a comeback)

    http://arxiv.org/abs/arXiv:1402.1038
    A note on entanglement entropy and quantum geometry
    Norbert Bodendorfer
    (entanglement entropy=the other kind)

    http://arxiv.org/abs/1401.7731
    Quantization of systems with temporally varying discretization II: Local evolution moves
    Philipp A Hoehn
    (part of Dittrich team's reformulation)

    http://arxiv.org/abs/1401.6562
    Planck stars
    Carlo Rovelli, Francesca Vidotto
    (delayed rebound BH)

    http://arxiv.org/abs/arXiv:1401.6441
    A new vacuum for Loop Quantum Gravity
    Bianca Dittrich, Marc Geiller
    (reformulation by Dittrich group: incl. refinement, coarse-graining, classical limit)

    http://arxiv.org/abs/1401.6062
    Quantization of systems with temporally varying discretization I: Evolving Hilbert spaces
    Philipp A Hoehn
    (part of Dittrich group's reformulation)

    http://arxiv.org/abs/1401.5262
    Spacetime thermodynamics without hidden degrees of freedom
    Goffredo Chirco, Hal M. Haggard, Aldo Riello, Carlo Rovelli
    (GR recovered purely from LQG thermodynamics--no other d.o.f. needed)

    http://arxiv.org/abs/1401.5083
    Non-Commutative Geometry, Non-Associative Geometry and the Standard Model of Particle Physics
    Latham Boyle, Shane Farnsworth
    (carrying Alain Connes Standard Model a step further)

    http://arxiv.org/abs/1401.4452
    Black holes within Asymptotic Safety
    Benjamin Koch, Frank Saueressig
    (asym. safe. BH)

    http://arxiv.org/abs/arXiv:1401.0931
    Hamiltonian constraint in Euclidean LQG revisited: First hints of off-shell Closure
    Alok Laddha
    (problems with the Hamiltonian approach finally yielding)


    Admittedly the "dark matter particle" papers are not Loop-and-allied QG research, traditionally the focus of the poll. But because the make-up of DM is such a crucial issue I would like (unless there is serious objection) to make an exception this time, and include them.
     
    Last edited: Mar 5, 2014
  8. Mar 15, 2014 #7

    marcus

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    One more to add to the above list of 16 first quarter 2014 papers:
    ]http://arxiv.org/abs/1403.3190
    A curvature operator for LQG
    Emanuele Alesci, Mehdi Assanioussi, Jerzy Lewandowski
    (Submitted on 13 Mar 2014)
    We introduce a new operator in Loop Quantum Gravity - the 3D curvature operator - related to the 3-dimensional scalar curvature. The construction is based on Regge Calculus. We define it starting from the classical expression of the Regge curvature, then we derive its properties and discuss some explicit checks of the semi-classical limit.
    20 pages.


    =================
    Six of us have responded to the 2013 4th quarter poll so far. Warm thanks to Atyy, Basics, Chronos, Jason_0, and Nonlinearity for getting the ball rolling. I think we benefit collectively from seeing and trying to understand each other's perspectives on the importance of the various research directions in Loop-and-allied QG. I know I definitely do.

    Here's how the votes stack up on the poll so far.
    4 votes:
    http://arxiv.org/abs/1312.3253
    General Relativity from a Thermodynamic Perspective
    Thanu Padmanabhan
    (Submitted on 11 Dec 2013)
    53 pages

    2 votes:
    http://arxiv.org/abs/1312.3595
    Hawking radiation from a spherical loop quantum gravity black hole
    Rodolfo Gambini, Jorge Pullin
    (Submitted on 12 Dec 2013)
    13 pages

    http://arxiv.org/abs/1312.1538
    Gravitational Energy, Local Holography and Non-equilibrium Thermodynamics
    Laurent Freidel
    (Submitted on 5 Dec 2013)
    41 pages, 3 figures

    http://arxiv.org/abs/1311.0054
    Relative information at the foundation of physics
    Carlo Rovelli
    (Submitted on 31 Oct 2013)
    3 pages. Second prize in the 2013 FQXi contest "It From Bit or Bit From It?"

    http://arxiv.org/abs/1310.7786
    Group field theory as the 2nd quantization of Loop Quantum Gravity
    Daniele Oriti
    (Submitted on 29 Oct 2013)
    23 pages, 5 figures

    http://arxiv.org/abs/1310.2174
    Radiative corrections to the EPRL-FK spinfoam graviton
    Aldo Riello
    (Submitted on 8 Oct 2013)
    13 pages, 4 figures

    http://arxiv.org/abs/1306.1058
    Quantum gravity from the point of view of locally covariant quantum field theory
    Romeo Brunetti, Klaus Fredenhagen, Katarzyna Rejzner
    (Submitted on 5 Jun 2013)
    51 pages

    1 vote:
    http://arxiv.org/abs/1312.7273
    On How Neutrino Protects the Axion
    Gia Dvali, Sarah Folkerts, Andre Franca
    (Submitted on 27 Dec 2013)
    9 pages

    http://arxiv.org/abs/1312.3657
    Structural aspects of loop quantum gravity and loop quantum cosmology from an algebraic perspective
    Alexander Stottmeister, Thomas Thiemann
    (Submitted on 12 Dec 2013)
    45 pages

    http://arxiv.org/abs/1311.7565
    Time evolution as refining, coarse graining and entangling
    Bianca Dittrich, Sebastian Steinhaus
    (Submitted on 29 Nov 2013)
    33 pages, 9 figures

    http://arxiv.org/abs/1311.2898
    Matter matters in asymptotically safe quantum gravity
    Pietro Donà, Astrid Eichhorn, Roberto Percacci
    (Submitted on 12 Nov 2013)
    22 pages, 18 figures, 4 tables

    http://arxiv.org/abs/1311.0186
    Twistor relative locality
    Lee Smolin
    (Submitted on 1 Nov 2013)
    10 pages

    http://arxiv.org/abs/1310.6728
    Quantization ambiguities and bounds on geometric scalars in anisotropic loop quantum cosmology
    Parampreet Singh, Edward Wilson-Ewing
    (Submitted on 24 Oct 2013)
    34 pages

    http://arxiv.org/abs/1310.5167
    A Gravitational Origin of the Arrows of Time
    Julian Barbour, Tim Koslowski, Flavio Mercati
    (Submitted on 18 Oct 2013)
    44+14 pages, 8 figures, 1 table

    http://arxiv.org/abs/1310.3362
    Deformation Operators of Spin Networks and Coarse-Graining
    Etera R. Livine
    (Submitted on 12 Oct 2013)
    24 pages

    http://arxiv.org/abs/arXiv:1309.0352
    Cosmological perturbations in teleparallel Loop Quantum Cosmology
    Jaime Haro
    (Submitted on 2 Sep 2013)
    18 pages. Journal of Cosmology and Astroparticle Physics
     
    Last edited: Mar 15, 2014
  9. Mar 25, 2014 #8

    marcus

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    New candidates for the first quarter MIP poll are included with their abstracts:

    http://arxiv.org/abs/1403.6396
    Viability of the matter bounce scenario in Loop Quantum Cosmology from BICEP2 last data
    Jaume de Haro, Jaume Amorós
    (Submitted on 25 Mar 2014)
    The CMB map provided by the Planck project constrains the value of the ratio of tensor-to-scalar perturbations, namely r, to be smaller than 0.11 (95% CL). This bound rules out the simplest models of inflation. However, recent data from BICEP2 is in strong tension with this constrain, as it finds a value r=0.20+0.07−0.05 with r=0 disfavored at 7.0σ, which allows these simplest inflationary models to survive. The remarkable fact is that, even though the BICEP2 experiment was conceived to search for evidence of inflation, its experimental data matches correctly theoretical results coming from the matter bounce scenario (the alternative model to the inflationary paradigm). More precisely, most bouncing cosmologies do not pass Planck's constrains due to the smallness of the value of the tensor/scalar ratio r≤0.11, but with new BICEP2 data some of them fit well with experimental data. This is the case with the matter bounce scenario in the teleparallel version of Loop Quantum Cosmology.
    4 pages, 1 figure

    http://arxiv.org/abs/1403.3190
    A curvature operator for LQG
    Emanuele Alesci, Mehdi Assanioussi, Jerzy Lewandowski
    (Submitted on 13 Mar 2014)
    We introduce a new operator in Loop Quantum Gravity - the 3D curvature operator - related to the 3-dimensional scalar curvature. The construction is based on Regge Calculus. We define it starting from the classical expression of the Regge curvature, then we derive its properties and discuss some explicit checks of the semi-classical limit.
    20 pages.

    http://arxiv.org/abs/1402.6708
    A one-dimensional action for simplicial gravity in three dimensions
    Wolfgang M. Wieland
    (continuum limit in simplified case, model succeeds at recovering the Ponzano-Regge amplitudes.)

    http://arxiv.org/abs/1402.6613
    Numerical simulations of a loop quantum cosmos: robustness of the quantum bounce and the validity of effective dynamics
    Peter Diener, Brajesh Gupt, Parampreet Singh
    (further numerical confirmation of the bounce and of Loop cosmology's equation model)

    http://arxiv.org/abs/1402.4138
    Near-Horizon Radiation and Self-Dual Loop Quantum Gravity
    Marc Geiller, Karim Noui
    (Ashtekar-type, self-dual variables making a comeback)

    http://arxiv.org/abs/1402.4119
    An unidentified line in X-ray spectra of the Andromeda galaxy and Perseus galaxy cluster
    Alexey Boyarsky, Oleg Ruchayskiy, Dmytro Iakubovskyi, Jeroen Franse
    (possible dark matter particle?)

    http://arxiv.org/abs/arXiv:1402.3155
    Quantum Reduced Loop Gravity: Semiclassical limit
    Emanuele Alesci, Francesco Cianfrani
    (semiclassical limit)

    http://arxiv.org/abs/1402.2301
    Detection of An Unidentified Emission Line in the Stacked X-ray spectrum of Galaxy Clusters
    Esra Bulbul, Maxim Markevitch, Adam Foster, Randall K. Smith, Michael Loewenstein, Scott W. Randall
    (hint of dark matter particle)

    http://arxiv.org/abs/arXiv:1402.2084
    Black Hole Entropy in Loop Quantum Gravity, Analytic Continuation, and Dual Holography
    Muxin Han
    (Ashtekar-type, self-dual variables making a comeback)

    http://arxiv.org/abs/arXiv:1402.1038
    A note on entanglement entropy and quantum geometry
    Norbert Bodendorfer
    (entanglement entropy=the other kind)

    http://arxiv.org/abs/1401.7731
    Quantization of systems with temporally varying discretization II: Local evolution moves
    Philipp A Hoehn
    (part of Dittrich team's reformulation)

    http://arxiv.org/abs/1401.6562
    Planck stars
    Carlo Rovelli, Francesca Vidotto
    (delayed rebound BH)

    http://arxiv.org/abs/arXiv:1401.6441
    A new vacuum for Loop Quantum Gravity
    Bianca Dittrich, Marc Geiller
    (reformulation by Dittrich group: incl. refinement, coarse-graining, classical limit)

    http://arxiv.org/abs/1401.6062
    Quantization of systems with temporally varying discretization I: Evolving Hilbert spaces
    Philipp A Hoehn
    (part of Dittrich group's reformulation)

    http://arxiv.org/abs/1401.5262
    Spacetime thermodynamics without hidden degrees of freedom
    Goffredo Chirco, Hal M. Haggard, Aldo Riello, Carlo Rovelli
    (GR recovered purely from LQG thermodynamics--no other d.o.f. needed)

    http://arxiv.org/abs/1401.5083
    Non-Commutative Geometry, Non-Associative Geometry and the Standard Model of Particle Physics
    Latham Boyle, Shane Farnsworth
    (carrying Alain Connes Standard Model a step further)

    http://arxiv.org/abs/1401.4452
    Black holes within Asymptotic Safety
    Benjamin Koch, Frank Saueressig
    (asym. safe. BH)

    http://arxiv.org/abs/arXiv:1401.0931
    Hamiltonian constraint in Euclidean LQG revisited: First hints of off-shell Closure
    Alok Laddha
    (problems with the Hamiltonian approach finally yielding)


    The "dark matter particle" papers are not Loop-and-allied QG research, traditionally the focus of the poll, but because the make-up of DM is such a crucial issue I would like to make an exception this time, and include them.
    There was a Jaume de Haro paper on TELEPARALLEL LQC on the 4th quarter 2013 MIP Poll. It has received only one vote so far (mine :biggrin:)
    http://arxiv.org/abs/arXiv:1309.0352
    Cosmological perturbations in teleparallel Loop Quantum Cosmology
    Jaime Haro
    (Submitted on 2 Sep 2013)
    18 pages. Journal of Cosmology and Astroparticle Physics
    However see de Haro's followup paper on this quarter's poll.
     
  10. Apr 1, 2014 #9

    marcus

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    Seven respondents have shared their perspectives on current Quantum Gravity research so far, in the 2013 4th quarter poll. Thanks Atyy, Basics, Chronos, David Horgan, Jason_0, and Nonlinearity!

    Here's how the votes stack up at present.
    5 votes:
    http://arxiv.org/abs/1312.3253
    General Relativity from a Thermodynamic Perspective
    Thanu Padmanabhan
    (Submitted on 11 Dec 2013)
    53 pages

    3 votes:
    http://arxiv.org/abs/1310.7786
    Group field theory as the 2nd quantization of Loop Quantum Gravity
    Daniele Oriti
    (Submitted on 29 Oct 2013)
    23 pages, 5 figures

    2 votes:
    http://arxiv.org/abs/1312.3595
    Hawking radiation from a spherical loop quantum gravity black hole
    Rodolfo Gambini, Jorge Pullin
    (Submitted on 12 Dec 2013)
    13 pages

    http://arxiv.org/abs/1312.1538
    Gravitational Energy, Local Holography and Non-equilibrium Thermodynamics
    Laurent Freidel
    (Submitted on 5 Dec 2013)
    41 pages, 3 figures

    http://arxiv.org/abs/1311.7565
    Time evolution as refining, coarse graining and entangling
    Bianca Dittrich, Sebastian Steinhaus
    (Submitted on 29 Nov 2013)
    33 pages, 9 figures

    http://arxiv.org/abs/1311.0054
    Relative information at the foundation of physics
    Carlo Rovelli
    (Submitted on 31 Oct 2013)
    3 pages. Second prize in the 2013 FQXi contest "It From Bit or Bit From It?"

    http://arxiv.org/abs/1310.2174
    Radiative corrections to the EPRL-FK spinfoam graviton
    Aldo Riello
    (Submitted on 8 Oct 2013)
    13 pages, 4 figures

    http://arxiv.org/abs/1306.1058
    Quantum gravity from the point of view of locally covariant quantum field theory
    Romeo Brunetti, Klaus Fredenhagen, Katarzyna Rejzner
    (Submitted on 5 Jun 2013)
    51 pages

    1 vote:
    http://arxiv.org/abs/1312.7273
    On How Neutrino Protects the Axion
    Gia Dvali, Sarah Folkerts, Andre Franca
    (Submitted on 27 Dec 2013)
    9 pages

    http://arxiv.org/abs/1312.3657
    Structural aspects of loop quantum gravity and loop quantum cosmology from an algebraic perspective
    Alexander Stottmeister, Thomas Thiemann
    (Submitted on 12 Dec 2013)
    45 pages

    http://arxiv.org/abs/1311.2898
    Matter matters in asymptotically safe quantum gravity
    Pietro Donà, Astrid Eichhorn, Roberto Percacci
    (Submitted on 12 Nov 2013)
    22 pages, 18 figures, 4 tables

    http://arxiv.org/abs/1311.0186
    Twistor relative locality
    Lee Smolin
    (Submitted on 1 Nov 2013)
    10 pages

    http://arxiv.org/abs/1310.6728
    Quantization ambiguities and bounds on geometric scalars in anisotropic loop quantum cosmology
    Parampreet Singh, Edward Wilson-Ewing
    (Submitted on 24 Oct 2013)
    34 pages

    http://arxiv.org/abs/1310.5167
    A Gravitational Origin of the Arrows of Time
    Julian Barbour, Tim Koslowski, Flavio Mercati
    (Submitted on 18 Oct 2013)
    44+14 pages, 8 figures, 1 table

    http://arxiv.org/abs/1310.3362
    Deformation Operators of Spin Networks and Coarse-Graining
    Etera R. Livine
    (Submitted on 12 Oct 2013)
    24 pages

    http://arxiv.org/abs/arXiv:1309.0352
    Cosmological perturbations in teleparallel Loop Quantum Cosmology
    Jaime Haro
    (Submitted on 2 Sep 2013)
    18 pages. Journal of Cosmology and Astroparticle Physics
     
  11. Apr 1, 2014 #10

    marcus

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    Dearly Missed

    Line-up for the 1st quarter MIP poll:

    http://arxiv.org/abs/1403.7482
    Deformed Spinor Networks for Loop Gravity: Towards Hyperbolic Twisted Geometries
    Maité Dupuis, Florian Girelli, Etera R. Livine
    (putting a non-zero cosmological constant into spinor-network terms)

    http://arxiv.org/abs/1403.6396
    Viability of the matter bounce scenario in Loop Quantum Cosmology from BICEP2 last data
    Jaume de Haro, Jaume Amorós
    (self-explanatory)

    http://arxiv.org/abs/1403.3190
    A curvature operator for LQG
    Emanuele Alesci, Mehdi Assanioussi, Jerzy Lewandowski
    (a new LQG operator - 3D curvature, based on Regge, with good semi-classical limit.)

    http://tel.archives-ouvertes.fr/docs/00/95/24/98/PDF/diss.pdf
    The Chiral Structure of Loop Quantum Gravity
    Wolfgang Wieland
    (appropriate treatment of time and Hamiltonian in 4d spin foam case, recovering EPRL amplitudes)

    http://arxiv.org/abs/1402.6708
    A one-dimensional action for simplicial gravity in three dimensions
    Wolfgang M. Wieland
    (consistency check of spinorial LQG in 3d, recovers Ponzano-Regge amplitudes.)

    http://arxiv.org/abs/1402.6613
    Numerical simulations of a loop quantum cosmos: robustness of the quantum bounce and the validity of effective dynamics
    Peter Diener, Brajesh Gupt, Parampreet Singh
    (further numerical confirmation of the bounce and of Loop cosmology's equation model)

    http://arxiv.org/abs/1402.4138
    Near-Horizon Radiation and Self-Dual Loop Quantum Gravity
    Marc Geiller, Karim Noui
    (Ashtekar-type, self-dual variables making a comeback)

    http://arxiv.org/abs/arXiv:1402.3155
    Quantum Reduced Loop Gravity: Semiclassical limit
    Emanuele Alesci, Francesco Cianfrani
    (semiclassical limit)

    http://arxiv.org/abs/arXiv:1402.2084
    Black Hole Entropy in Loop Quantum Gravity, Analytic Continuation, and Dual Holography
    Muxin Han
    (Ashtekar-type, self-dual variables making a comeback)

    http://arxiv.org/abs/arXiv:1402.1038
    A note on entanglement entropy and quantum geometry
    Norbert Bodendorfer
    (entropy = entanglement entropy)

    http://arxiv.org/abs/1401.7731
    Quantization of systems with temporally varying discretization II: Local evolution moves
    Philipp A Hoehn
    (part of Dittrich team's reformulation)

    http://arxiv.org/abs/1401.6562
    Planck stars
    Carlo Rovelli, Francesca Vidotto
    (delayed bounce model solves the black hole problems)

    http://arxiv.org/abs/arXiv:1401.6441
    A new vacuum for Loop Quantum Gravity
    Bianca Dittrich, Marc Geiller
    (reformulation by Dittrich group: refinement, coarse-graining, classical limit)

    http://arxiv.org/abs/1401.6062
    Quantization of systems with temporally varying discretization I: Evolving Hilbert spaces
    Philipp A Hoehn
    (part of Dittrich group's reformulation)

    http://arxiv.org/abs/1401.5262
    Spacetime thermodynamics without hidden degrees of freedom
    Goffredo Chirco, Hal M. Haggard, Aldo Riello, Carlo Rovelli
    (GR derived solely from LQG thermodynamics)

    http://arxiv.org/abs/1401.5083
    Non-Commutative Geometry, Non-Associative Geometry and the Standard Model of Particle Physics
    Latham Boyle, Shane Farnsworth
    (improves on Alain Connes NCG Standard Model)

    http://arxiv.org/abs/1401.4452
    Black holes within Asymptotic Safety
    Benjamin Koch, Frank Saueressig
    (asym. safe BH)

    http://arxiv.org/abs/arXiv:1401.0931
    Hamiltonian constraint in Euclidean LQG revisited: First hints of off-shell Closure
    Alok Laddha
    (problems with the Hamiltonian approach finally yielding)

    Two "dark matter particle" papers are included by popular request:

    http://arxiv.org/abs/1402.4119
    An unidentified line in X-ray spectra of the Andromeda galaxy and Perseus galaxy cluster
    Alexey Boyarsky, Oleg Ruchayskiy, Dmytro Iakubovskyi, Jeroen Franse
    (possible dark matter particle?)

    http://arxiv.org/abs/1402.2301
    Detection of An Unidentified Emission Line in the Stacked X-ray spectrum of Galaxy Clusters
    Esra Bulbul, Maxim Markevitch, Adam Foster, Randall K. Smith, Michael Loewenstein, Scott W. Randall
    (hint of dark matter particle)
     
    Last edited: Apr 1, 2014
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