Reassessing the link between B -modes and inflation
We reevaluate the predictions of inflation regarding primordial gravity waves, which should appear as B-modes in the cosmic microwave background (CMB), in light of the fact that the standard inflationary paradigm is unable to account for the transition from an initially symmetric state into a nonsym...
Guardado en:
| Autor principal: | |
|---|---|
| Otros Autores: | , , |
| Formato: | Capítulo de libro |
| Lenguaje: | Inglés |
| Publicado: |
American Physical Society
2017
|
| Acceso en línea: | Registro en Scopus DOI Handle Registro en la Biblioteca Digital |
| Aporte de: | Registro referencial: Solicitar el recurso aquí |
| LEADER | 17374caa a22009497a 4500 | ||
|---|---|---|---|
| 001 | PAPER-17772 | ||
| 003 | AR-BaUEN | ||
| 005 | 20230518204909.0 | ||
| 008 | 190410s2017 xx ||||fo|||| 00| 0 eng|d | ||
| 024 | 7 | |2 scopus |a 2-s2.0-85037105010 | |
| 040 | |a Scopus |b spa |c AR-BaUEN |d AR-BaUEN | ||
| 100 | 1 | |a León, G. | |
| 245 | 1 | 0 | |a Reassessing the link between B -modes and inflation |
| 260 | |b American Physical Society |c 2017 | ||
| 506 | |2 openaire |e Política editorial | ||
| 504 | |a Mortonson, M.J., Seljak, U., J. Cosmol. Astropart. Phys., 2014 (10), p. 035 | ||
| 504 | |a (2016) Astron. Astrophys., 586, p. A141. , Planck Collaboration | ||
| 504 | |a Kamionkowski, M., Kovetz, E.D., (2016) Annu. Rev. Astron. Astrophys., 54, p. 227 | ||
| 504 | |a Abbott, B.P., (2016) Phys. Rev. Lett., 116, p. 061102 | ||
| 504 | |a Taylor, J.H., Weisberg, J.M., (1982) Astrophys. J., 253, p. 908 | ||
| 504 | |a Perez, A., Sahlmman, H., Sudarsky, D., (2006) Classical Quantum Gravity, 23, p. 2317 | ||
| 504 | |a León, G., Kraiselburd, L., Landau, S., (2015) Phys. Rev. D, 92, p. 083516 | ||
| 504 | |a Bell, J.S., (1981) Quantum Gravity II, , (Oxford University Press, New York) | ||
| 504 | |a Albert, D.Z., (1992) Quantum Mechanics and Experience, , (Harvard University Press, Cambridge, MA) | ||
| 504 | |a Maudlin, T., (1995) Topoi, 14, p. 7 | ||
| 504 | |a Ananda, K.N., Clarkson, C., Wands, D., (2007) Phys. Rev. D, 75, p. 123518 | ||
| 504 | |a Baumann, D., Steinhardt, P.J., Takahashi, K., Ichiki, K., (2007) Phys. Rev. D, 76, p. 084019 | ||
| 504 | |a Huang, Q.G., Wang, S., Zhao, W., J. Cosmol. Astropart. Phys., 2015 (15), p. 035 | ||
| 504 | |a Sudarsky, D., (2011) Int. J. Mod. Phys. D, 20, p. 509 | ||
| 504 | |a Weinberg, S., (2008) Cosmology, , (Oxford University Press, New York) | ||
| 504 | |a Mukhanov, V.F., (2005) Physical Foundations of Cosmology, , (Cambridge University Press, Cambridge, England) | ||
| 504 | |a Martin, J., Vennin, V., Peter, P., (2012) Phys. Rev. D, 86, p. 103524 | ||
| 504 | |a Das, S., Lochan, K., Sahu, S., Singh, T.P., (2014) Phys. Rev. D, 89, p. 109902 | ||
| 504 | |a León, G., De Unanue, A., Sudarsky, D., (2011) Classical Quantum Gravity, 28, p. 155010 | ||
| 504 | |a Cañate, P., Pearle, P., Sudarsky, D., (2013) Phys. Rev. D, 87, p. 104024 | ||
| 504 | |a Diez-Tejedor, A., Sudarsky, D., J. Cosmol. Astropart. Phys., 2012 (7), p. 045 | ||
| 504 | |a León, G., Sudarsky, D., (2010) Classical Quantum Gravity, 27, p. 225017 | ||
| 504 | |a Bassi, A., Ghirardi, G., (2003) Phys. Rep., 379, p. 257 | ||
| 504 | |a Okon, E., Sudarsky, D., (2014) Found. Phys., 44, p. 114 | ||
| 504 | |a Okon, E., Sudarsky, D., (2015) Found. Phys., 45, p. 461 | ||
| 504 | |a Okon, E., Sudarsky, D., (2016) Classical Quantum Gravity, 33, p. 225015 | ||
| 504 | |a Huggett, N., Callender, C., (2001) Philos. Sci., 68, p. S382 | ||
| 504 | |a Mattingly, J., (2005) The Universe of General Relativity, pp. 325-338. , edited by A. J. Kox and J. Eisenstaedt (Birkhäuser, Boston) | ||
| 504 | |a Mattingly, J., (2006) Phys. Rev. D, 73, p. 064025 | ||
| 504 | |a Carlip, S., (2008) Classical Quantum Gravity, 25, p. 154010 | ||
| 504 | |a Jacobson, T., (1995) Phys. Rev. Lett., 75, p. 1260 | ||
| 504 | |a Hu, B.L., (2009) J. Phys. Conf. Ser., 174, p. 012015 | ||
| 504 | |a Wheeler, J.A., (1964) Relativity, Groups, and Topology, , edited by B. S. DeWitt and C. DeWitt (Gordon and Breach, New York) | ||
| 504 | |a Finkelstein, D., (1969) Phys. Rev., 184, p. 1261 | ||
| 504 | |a Konopka, T., Markopoulou, F., Severini, S., (2008) Phys. Rev. D, 77, p. 104029 | ||
| 504 | |a Oriti, D., (2009) Approaches to Quantum Gravity, , edited by D. Oriti (Cambridge University Press, Cambridge, England) | ||
| 504 | |a Steinacker, H., (2010) Classical Quantum Gravity, 27, p. 133001 | ||
| 504 | |a Isham, C.J., (1992) Imperial College, Report No. 91-92-25 | ||
| 504 | |a Ashoorioon, A., Dev, P.S.B., Mazumdar, A., (2014) Mod. Phys. Lett. A, 29, p. 1450163 | ||
| 504 | |a Markkanen, T., Rasanen, S., Wahlman, P., (2015) Phys. Rev. D, 91, p. 084064 | ||
| 504 | |a Pearle, P., (1989) Phys. Rev. A, 39, p. 2277 | ||
| 504 | |a Okon, E., Sudarsky, D., arXiv:1701.02963; León, G., Majhi, A., Okon, E., Sudarsky, D., (to be published); Dodelson, S., (2003) Modern Cosmology, , (Academic Press, New York) | ||
| 504 | |a Seljak, U., (1994) Astrophys. J., 435, p. L87 | ||
| 504 | |a Baumann, D., The Physics of Inflation - A Course for Graduate Students in Particle Physics and Cosmology, , http://www.damtp.cam.ac.uk/user/db275/TEACHING/INFLATION/Lectures.pdf | ||
| 520 | 3 | |a We reevaluate the predictions of inflation regarding primordial gravity waves, which should appear as B-modes in the cosmic microwave background (CMB), in light of the fact that the standard inflationary paradigm is unable to account for the transition from an initially symmetric state into a nonsymmetric outcome. We show that the incorporation of an element capable of explaining such a transition dramatically alters the prediction for the shape and size of the B-mode spectrum. In particular, we find that by adapting a realistic objective collapse model to the situation at hand, the B-mode spectrum becomes strongly suppressed with respect to the standard prediction. We conclude that the failure to detect B-modes in the CMB does not rule out the simplest inflationary models. © 2017 American Physical Society. |l eng | |
| 536 | |a Detalles de la financiación: National Research Council of Science and Technology | ||
| 536 | |a Detalles de la financiación: Consejo Interinstitucional de Ciencia y Tecnología | ||
| 536 | |a Detalles de la financiación: Universidad Nacional Autónoma de México, http://sws.geonames.org/3996063/ | ||
| 536 | |a Detalles de la financiación: Consejo Nacional de Ciencia y Tecnología | ||
| 536 | |a Detalles de la financiación: China Medical Board | ||
| 536 | |a Detalles de la financiación: Consejo Nacional de Investigaciones Científicas y Técnicas | ||
| 536 | |a Detalles de la financiación: et al. León Gabriel 1,2 ,* Majhi Abhishek 3 ,† Okon Elias 4 ,‡ Sudarsky Daniel 3 ,§ Departamento de Física, Facultad de Ciencias Exactas y Naturales, 1 Universidad de Buenos Aires , Ciudad Universitaria—Pabellón I, 1428 Buenos Aires, Argentina Grupo de Astrofísica, Relatividad y Cosmología, Facultad de Ciencias Astronómicas y Geofísicas, 2 Universidad Nacional de La Plata , Paseo del Bosque S/N (1900) La Plata, Argentina Instituto de Ciencias Nucleares, 3 Universidad Nacional Autónoma de México , Mexico City 04510, Mexico Instituto de Investigaciones Filosóficas, 4 Universidad Nacional Autónoma de México , Mexico City 04510, Mexico * gleon@fcaglp.unlp.edu.ar † abhishek.majhi@gmail.com ‡ eokon@filosoficas.unam.mx § sudarsky@nucleares.unam.mx 6 November 2017 15 November 2017 96 10 101301 8 April 2017 © 2017 American Physical Society 2017 American Physical Society We reevaluate the predictions of inflation regarding primordial gravity waves, which should appear as B -modes in the cosmic microwave background (CMB), in light of the fact that the standard inflationary paradigm is unable to account for the transition from an initially symmetric state into a nonsymmetric outcome. We show that the incorporation of an element capable of explaining such a transition dramatically alters the prediction for the shape and size of the B -mode spectrum. In particular, we find that by adapting a realistic objective collapse model to the situation at hand, the B -mode spectrum becomes strongly suppressed with respect to the standard prediction. We conclude that the failure to detect B -modes in the CMB does not rule out the simplest inflationary models. Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México http://dx.doi.org/10.13039/501100006087 Dirección General Asuntos del Personal Académico, Universidad Nacional Autónoma de México DGAPA, UNAM http://sws.geonames.org/3996063/ Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México http://dx.doi.org/10.13039/501100006087 Dirección General Asuntos del Personal Académico, Universidad Nacional Autónoma de México DGAPA, UNAM http://sws.geonames.org/3996063/ IG100316 Consejo Nacional de Ciencia y Tecnología http://dx.doi.org/10.13039/501100003141 National Council of Science and Technology, Mexico CONACYT http://sws.geonames.org/3996063/ 101712 Consejo Nacional de Investigaciones Científicas y Técnicas http://dx.doi.org/10.13039/501100002923 National Scientific and Technical Research Council CONICET http://sws.geonames.org/3865483/ The exquisite matching between observations of temperature anisotropies in the cosmic microwave background (CMB) and the generic predictions of inflation provides a powerful justification for the recent consolidation of the inflationary paradigm as a cornerstone of modern cosmology. However, such a paradigm also makes predictions for the shape and amplitude of primordial gravity waves, which should be observable in the B -mode polarization of the CMB. The fact that, so far, such B -modes have not been observed has been used to severely constrain the set of viable inflationary models [1–3] . Moreover, the recent detection of gravity waves by LIGO [4] removes all lingering doubts about the reality of such waves (if there were any remaining, given the dramatic indirect evidence provided by the binary pulsar studies [5] ). This only increases the urgency to resolve the tension generated by the predictions regarding B -modes and our failure to detect them. As initially argued in [6] , the standard inflationary account for the emergence of the primordial perturbations lacks a crucial element capable of accounting for the transition from the initially homogeneous and isotropic quantum state into a state lacking such symmetries. The objective of this paper is to show that the adoption of a framework that explicitly introduces this element drastically modifies the predictions for the shape and amplitude of the primordial gravity waves (without also altering confirmed predictions of inflation) [7] . As a result, we conclude that the impact of the B -polarization null results on the viability of various inflationary models has to be reexamined. In particular, we establish that, contrary to what has been argued, the failure to detect B -modes in the CMB does not rule out the simplest inflationary models. The crucial observation overlooked by the standard account concerns the way in which the quantum fluctuations of the completely homogeneous and isotropic state that characterizes the early stages of inflation (i.e., the Bunch-Davies vacuum or related states) are supposed to transform into actual inhomogeneities and anisotropies. The problem is that such “fluctuations” are nothing more than a characterization of the width of the wave function for the corresponding field degrees of freedom and not actual physical fluctuations. Therefore, they do not represent deviations from isotropy and homogeneity and cannot be used to explain departures from such symmetries. Of course, all these issues are connected with the notorious conceptual difficulties of quantum theory [9–11] , and, as such, they are often regarded as having no physical but only “philosophical” implications. However, the situation under consideration is one of the few clear instances where such expectations do not hold. As we will see below in detail, the viability of many inflationary models, including some of the simplest ones, strongly depends on the point of view adopted regarding interpretational issues. Before advancing our own proposal, we review a few aspects of the standard approach to inflationary cosmology. The starting point is the action of a scalar field ϕ , the inflaton, with potential V , coupled to gravity, S = ∫ d 4 x - g [ 1 16 π G R [ g ] - 1 / 2 ∇ a ϕ ∇ b ϕ g a b - V ( ϕ ) ] . (1) One then splits both the metric g and the scalar field ϕ into spatially homogeneous backgrounds, g 0 and ϕ 0 , and inhomogeneous fluctuations, δ g and δ ϕ . The backgrounds are taken to be the spatially flat Friedmann-Robertson-Walker (FRW) universe, with line element d s 2 = a ( η ) 2 [ - d η 2 + δ i j d x i d x j ] , and a homogeneous scalar field ϕ 0 ( η ) (with η being a conformal time). The solution for the scale factor a ( η ) during the inflationary era is a ( η ) = [ - 1 / H η ] ( 1 + ε ) , with H 2 ≈ ( 8 π / 3 ) G V and ε ≡ 1 - H ˙ / H 2 (where H ≡ a ˙ a ). The parameter ε is called the slow-roll parameter and, during the inflationary stage, is considered to be very small, ε ≪ 1 . Also, the scalar field ϕ 0 is supposed to be in the slow-roll regime, i.e., ϕ ˙ 0 = - ( a 3 / 3 a ˙ ) V ′ . We ignore the fact that the functional form of a ( η ) changes after inflation, and for definiteness, we set a ( η ) = 1 at the present cosmological time and assume that the inflationary regime starts at η = - T (note that T > 0 ) and ends at η = η 0 , which is negative and very small in absolute terms. Regarding the perturbations, one works in the so-called longitudinal gauge, where the perturbed metric is written as d s 2 = a ( η ) 2 { - ( 1 + 2 Ψ ) d η 2 + [ ( 1 - 2 Ψ ) δ i j + h i j ] d x i d x j } , (2) where Ψ stands for the scalar perturbation, usually known as the Newtonian potential, and the transverse traceless h i j stands for the tensor perturbations, corresponding to gravity waves. The next step in the standard treatment is to introduce quantum mechanics into the picture. This is done by quantizing the perturbations Ψ , δ ϕ , and h i j as fields on the background provided by the spacetime g 0 and the classical inflaton field ϕ 0 . In fact, the equations of motion for these perturbations lead to an interaction between Ψ and δ ϕ that makes it convenient to directly quantize the field v = a ( δ ϕ + ϕ ˙ 0 H Ψ ) , known as the Mukhanov-Sasaki variable. One also assumes that the quantum state of the field is the Bunch-Davies vacuum [12] . Finally, one identifies the vacuum uncertainties in the spatial Fourier components of v , Ψ , and h i j with actual, physical inhomogeneities in the CMB, leading, as is well known, to a spectacular matching between predictions and observations. Now, since both the scalar and tensor perturbations are treated equally in this setting, it is not surprising, given a specific inflationary model, for there to be a close similarity in their predicted amplitudes and shapes. In fact, the standard estimates for the power spectra of the scalar and tensor perturbations are given by P s S ( q ) ≃ G H 2 q 3 ε and P h S ( q ) ≃ G H 2 q 3 , (3) respectively, where the superscript S stands for “standard” scenario (in contrast with the “collapse” scenario introduced below) [13] . Therefore, for r , the ratio of the amplitudes in tensor and scalar perturbations, one finds r ≃ ε . As ε is also connected with the tilt in the scalar spectrum [16] , empirical constraints on that quantity can be used to limit the viability of various simple inflationary models. In particular, measurements of the amplitude of scalar perturbations, combined with the failure to detect tensor perturbations, have been used to discriminate among inflationary models and even to rule out some of the simplest ones [1–3] . There are, however, a few problematic aspects within the standard approach that call into question some of its conclusions. The first, already mentioned above, is the fact that the identification between quantum uncertainties and actual inhomogeneities is not well founded. The issue, again, is that such uncertainties represent the width of the wave function and not actual fluctuations. Therefore, just as the spread in position in the ground state of a 1D harmonic oscillator | ||
| 593 | |a Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria-Pabellón i, Buenos Aires, 1428, Argentina | ||
| 593 | |a Grupo de Astrofísica, Relatividad y Cosmología, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de la Plata, Paseo del Bosque S/N, La Plata, 1900, Argentina | ||
| 593 | |a Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico | ||
| 593 | |a Instituto de Investigaciones Filosóficas, Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico | ||
| 700 | 1 | |a Majhi, A. | |
| 700 | 1 | |a Okon, E. | |
| 700 | 1 | |a Sudarsky, D. | |
| 773 | 0 | |d American Physical Society, 2017 |g v. 96 |k n. 10 |p Phy. Rev. D |x 24700010 |t Physical Review D | |
| 856 | 4 | 1 | |u https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037105010&doi=10.1103%2fPhysRevD.96.101301&partnerID=40&md5=e2bccf883b83102ca8d90ebd4b5a17ad |y Registro en Scopus |
| 856 | 4 | 0 | |u https://doi.org/10.1103/PhysRevD.96.101301 |y DOI |
| 856 | 4 | 0 | |u https://hdl.handle.net/20.500.12110/paper_24700010_v96_n10_p_Leon |y Handle |
| 856 | 4 | 0 | |u https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_24700010_v96_n10_p_Leon |y Registro en la Biblioteca Digital |
| 961 | |a paper_24700010_v96_n10_p_Leon |b paper |c PE | ||
| 962 | |a info:eu-repo/semantics/article |a info:ar-repo/semantics/artículo |b info:eu-repo/semantics/publishedVersion | ||
| 999 | |c 78725 | ||