Interaction of the Barbero-Immirzi field with matter and pseudoscalar perturbations

Mercuri, Simone; Taveras, Victor

doi:10.1103/physrevd.80.104007

Cited by 111 publications

(113 citation statements)

References 48 publications

(120 reference statements)

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“…The Pontryagin term in the action is involved in anomaly cancellation [30]. Such a term also appears naturally in heterotic superstring theory [30][31][32] and loop quantum gravity [33][34][35]. Dynamical CS gravity also arises naturally in effective field theories of inflation [36].…”

Section: Introductionmentioning

confidence: 99%

Isolated and binary neutron stars in dynamical Chern-Simons gravity

et al. 2013

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In Ref.[1], the Chern-Simons correction to the osculating orbital elements due to the dipole-dipole interaction for the scalar field was derived in Eq. (130) by integrating out the interaction Lagrangian, which was taken to be the kinetic term for the scalar field [Eq. (122) in [1]], using the scalar field solution. However, such kinetic term only leads to the left-hand side of the evolution equation for the scalar field, i.e.where J is the effective source term of the scalar field equation [2]. In order to obtain the correct interaction Lagrangian, one also needs to include the source term (L source ) that reproduces the right-hand side of the above evolution equation. The Lagrangian density for such an additional term is given by −ϑJ. Therefore, Eq. (126) needs to be changed towhere L source,int is the interaction part of the source term Lagrangian density. Notice that, by accounting for such additional term, the sign of the interaction Lagrangian now flips. This means that the sign in Eqs. (127), (129) and (130) needs to be reversed. The results in Sec. IX B are unaffected since we have neglected contribution from the dipole-dipole interaction because the spin of the secondary pulsar in the double binary pulsar is much smaller than that of the primary. We also report errors in App. B of [1]. In this appendix, we calculated dissipative corrections to the energy and angular momentum energy flux emitted from neutron star binaries based on calculations in [2]. However, some terms in the perturbed scalar and metric field equations were not properly accounted for in [2]. Taking these terms into account, we found that corrections to the gravitational energy and angular momentum flux due to metric perturbations enter at third post-Newtonian order relative to general relativity, which is of 1 post-Newtonian order higher than the effect due to the scalar field. Therefore, Apps. B.1.b and B.2.b in [1] are now irrelevant. We discuss this in more detail in [3].On the other hand, the scalar energy flux in App. B.1.a is affected as follows. First, the far-zone solution for the scalar field in Eq. (B3) becomesThen, the scalar energy flux in Eqs. (B5) and (B6) becomesrespectively. Finally, Eq. (B8) is corrected to T. Tanaka, Phys. Rev., D85, 064022 (2012), arXiv:1110.5950 [gr-qc].[3] K. Yagi, L. C. Stein, N. Yunes, and T. Tanaka, Phys. Rev., D93, 029902 (2016D93, 029902 ( ), arXiv:1110. We study isolated and binary neutron stars in dynamical Chern-Simons gravity. This theory modifies the Einstein-Hilbert action through the introduction of a dynamical scalar field coupled to the Pontryagin density. We here treat this theory as an effective model, working to leading order in the Chern-Simons coupling. We first construct isolated neutron star solutions in the slow-rotation expansion to quadratic order in spin. We find that isolated neutron stars acquire a scalar dipole charge that corrects its spin angular momentum to linear order in spin and corrects its mass and quadrupole moment to quadratic order in spin, as measured by ...

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Section: Introductionmentioning

confidence: 99%

Isolated and binary neutron stars in dynamical Chern-Simons gravity

et al. 2013

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“…However, when torsion is present (for instance, when it is generated by fermions or a spacetime-dependent Barbero-Immirzi field [18][19][20][21][22]), it is natural to include it explicitly in the fundamental action, so that the Holst term is completed by a torsion-torsion piece to form the Nieh-Yan invariant [17,23]. There are several other reasons why to prefer the latter alternative.…”

Section: Ij µmentioning

confidence: 99%

Erratum: Cosmological Bardeen-Cooper-Schrieffer condensate as dark energy [Phys. Rev. D81, 043511 (2010)]

Alexander¹,

Biswas²,

Calcagni³

2010

Phys. Rev. D

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We argue that the occurrence of late-time acceleration can conveniently be described by firstorder general relativity covariantly coupled to fermions. Dark energy arises as a Bardeen-CooperSchrieffer condensate of fermions which forms in the early universe. At late times, the gap and chemical potential evolve to have an equation of state with effective negative pressure, thus naturally leading to acceleration.

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“…Both of these theories are motivated from fundamental physics; they unavoidably arise as low-energy expansions of heterotic string theory [41][42][43][44]. Dynamical CS gravity also arises in loop quantum gravity when the Barbero-Immirzi parameter is promoted to a field in the presence of fermions [45][46][47].…”

Section: A Abc Of Quadratic Gravitymentioning

confidence: 99%

Erratum: Post-Newtonian, quasicircular binary inspirals in quadratic modified gravity [Phys. Rev. D85, 064022 (2012)]

et al. 2016

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In this erratum, we point out that the correction to the gravitational energy flux from compact binary inspirals in dynamical Chern-Simons gravity enters at third post-Newtonian order instead of second post-Newtonian order. We also correct the scalar energy flux at second post-Newtonian order by considering terms that we missed in the original paper. I. GRAVITATIONAL RADIATIONIn [1], we claimed that the correction to the gravitational energy flux, i.e. the energy flux from binary inspirals induced by the metric perturbation in dynamical Chern-Simons (dCS) gravity, enters at second postNewtonian (PN) order. Here, we point out that there are terms that we overlooked, and if we take these terms into account properly, the 2PN terms cancel and the correction enters at 3PN order. where h µν and h µν are the General Relativity (GR) and dCS metric perturbations respectively. We worked in harmonic gauge,h µν ,ν = 0 =h µν ,ν , where we defined the metric perturbations viāWe then expanded the modified Einstein equations, focusing on the dCS correction and keeping terms up to linear order in h µν andh µν :(1)where η is the d'Alembertian operator of flat spacetime andK 1 Recall that a term in an expression is said to be of N th PN order if it is proportional to v 2N relative to the leading-order term in that same expression.We then solved this wave equation in the far zone (FZ), for field points much larger than the gravitational wave (GW) wavelength of the system, using a Green's function. The Green's function solution requires the integration ofK(1) µν and T (ϑ)µν , and thus of the fields h µν and ϑ evaluated in the near zone (NZ), i.e. at field point distances smaller than the GW wavelength of the system, but far from the location of the objects. To leading PN order, the NZ fields are given bywhere µ i A is the NZ scalar dipole charge, withfor a black hole, where χ A andŜ i A represent respectively the dimensionless spin parameter and the unit spin angular momentum vector of the Ath binary constituent. The dominant contribution to the FZ solution comes from the integration of the T (ϑ) µν term in Eq. (4), which is roughly of the following PN order:where b is the binary's separation, v is the binary's (relative) velocity and r is the FZ field point distance.Comparing this with the GR, leading PN contribution, h One of the terms we neglected in Eq. (4) where we used that T mat ij ∼ ρv i v j with ρ representing the energy density of one of the bodies. From the above equations, we see that the (hT mat µν ) and t (1) µν terms give 3PN and 2PN corrections to the gravitational radiation respectively. Notice that the latter is of the same order as the contribution from T (ϑ) µν that we calculated in [1].Given this, what is the correct dCS corrections to the gravitational energy flux? One can answer this question by using a very useful (and standard) trick employed regularly in the PN expansion of GR. Due to the gauge conditionh µν ,ν = 0, the tensor S µν in Eq. (13) is conserved, i.e. S µν ,ν = 0. Thanks to this conservation law,...

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Interaction of the Barbero-Immirzi field with matter and pseudoscalar perturbations

Cited by 111 publications

References 48 publications

Isolated and binary neutron stars in dynamical Chern-Simons gravity

Isolated and binary neutron stars in dynamical Chern-Simons gravity

Erratum: Cosmological Bardeen-Cooper-Schrieffer condensate as dark energy [Phys. Rev. D81, 043511 (2010)]

Erratum: Post-Newtonian, quasicircular binary inspirals in quadratic modified gravity [Phys. Rev. D85, 064022 (2012)]

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