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18 results on '"Chen Xingang"'

1. Cosmology of Single Species Hidden Dark Matter

Author

Lin, Weikang, Chen, Xingang, Ganjoo, Himanish, Hou, Liqiang, and Mack, Katherine J.

Subjects
High Energy Physics - Phenomenology, Cosmology and Nongalactic Astrophysics (astro-ph.CO), High Energy Physics - Phenomenology (hep-ph), FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), General Relativity and Quantum Cosmology, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Cosmology and astrophysics provide various ways to study the properties of dark matter even if they have negligible non-gravitational interactions with the Standard Model particles and remain hidden. We study a type of hidden dark matter model in which the dark matter is completely decoupled from the Standard Model sector except gravitationally, and consists of a single species with a conserved comoving particle number. This category of hidden dark matter includes models that act as warm dark matter but is more general. In particular, in addition to having an independent temperature from the Standard Model sector, it includes cases in which dark matter is in its own thermal equilibrium or is free-streaming, obeys fermionic or bosonic statistics, and processes a chemical potential that controls the particle occupation number. While the usual parameterization using the free-streaming scale or the particle mass no longer applies, we show that all cases can be well approximated by a set of functions parameterized by only one parameter as long as the chemical potential is nonpositive: the characteristic scale factor at the time of the relativistic-to-nonrelativistic transition. We study the constraints from Big Bang Nucleosynthesis, the cosmic microwave background, the Lyman-$\alpha$ forest, and the smallest halo mass. We show that the most significant phenomenological impact is the suppression of the small-scale matter power spectrum -- a typical feature when the dark matter has a velocity dispersion or pressure at early times. So far, small dark matter halos provide the strongest constraint, limiting the transition scale factor to be no larger than $\sim1.4\times10^{-4}$ times the scale factor at matter-radiation equality., Comment: 24 pages, 3 tables, 8 figures, comments welcome

Published
2023

2. New inflationary probes of axion dark matter

Author

Chen, Xingang, Fan, JiJi, and Li, Lingfeng

Subjects
High Energy Physics - Theory, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Cosmology and Nongalactic Astrophysics (astro-ph.CO), High Energy Physics - Theory (hep-th), FOS: Physical sciences, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

If a light axion is present during inflation and becomes part of dark matter afterwards, its quantum fluctuations contribute to dark matter isocurvature. In this article, we introduce a whole new suite of cosmological observables for axion isocurvature, which could help test the presence of axions, as well as its coupling to the inflaton and other heavy spectator fields during inflation such as the radial mode of the Peccei-Quinn field. They include correlated clock signals in the curvature and isocurvature spectra, and mixed cosmological-collider non-Gaussianities involving both curvature and isocurvature fluctuations with shapes and running unconstrained by the current data. Taking into account of the existing strong constraints on axion isocurvature fluctuations from the CMB, these novel signals could still be sizable and potentially observable. In some models, the signals, if observed, could even help us significantly narrow down the range of the inflationary Hubble scale, a crucial parameter difficult to be determined in general, independent of the tensor mode., Comment: 44 pages, 15 figures

Published
2023
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3. Early-Universe-Physics Insensitive and Uncalibrated Cosmic Standards: Constraints on $��_{\rm{m}}$ and Implications for the Hubble Tension

Author

Lin, Weikang, Chen, Xingang, and Mack, Katherine J.

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th), FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics
Abstract

To further shed light on whether pre-recombination models can resolve the Hubble tension, we explore constraints on the cosmic background evolution that are insensitive to early-universe physics. The analysis of the cosmic microwave background (CMB) anisotropy has been thought to highly rely on early-universe physics. However, we show that the fact that the sound horizon at recombination being close to that at the end of the drag epoch is insensitive to early-universe physics. This allows us to link the absolute sizes of the two horizons and treat them as free parameters. Jointly, the CMB peak angular size, Baryon Acoustic Oscillations (BAO), and Type Ia supernovae can be used as "early-universe-physics insensitive and uncalibrated cosmic standards", which measure the cosmic history from recombination to today. They can set strong and robust constraints on the post-recombination cosmic background, especially the matter density parameter with $��_{\rm{m}}=0.302\pm0.008$ ($68\%$ C.L.) assuming a flat $��$CDM after recombination. When we combine these with other non-local observations, we obtain several constraints on $H_0$ with significantly reduced sensitivity to early-universe physics. These are all more consistent with the Planck 2018 result than the local measurement results such as those based on Cepheids. This suggests a tension between the post-recombination, but non-local, observations and the local measurements which cannot be resolved by modifying pre-recombination early universe physics., Results updated with stellar-age constraints; conclusion unchanged. Accepted for publication in ApJ

Published
2021
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4. Inflation and Dark Energy from spectroscopy at z > 2

Author

Ferraro, Simone, Wilson, Michael J., Abidi, Muntazir, Alonso, David, Ansarinejad, Behzad, Armstrong, Robert, Asorey, Jacobo, Avelino, Arturo, Baccigalupi, Carlo, Bandura, Kevin, Battaglia, Nicholas, Bavdhankar, Chetan, Bernal, Jos�� Luis, Beutler, Florian, Biagetti, Matteo, Blanc, Guillermo A., Blazek, Jonathan, Bolton, Adam S., Borrill, Julian, Frye, Brenda, Buckley-Geer, Elizabeth, Bull, Philip, Burgess, Cliff, Byrnes, Christian T., Cai, Zheng, Castander, Francisco J, Castorina, Emanuele, Chang, Tzu-Ching, Chaves-Montero, Jon��s, Chen, Shi-Fan, Chen, Xingang, Balland, Christophe, Y��che, Christophe, Cohn, J. D., Coulton, William, Courtois, Helene, Croft, Rupert A. C., Cyr-Racine, Francis-Yan, D'Amico, Guido, Dawson, Kyle, Delabrouille, Jacques, Dey, Arjun, Dor��, Olivier, Douglass, Kelly A., Yutong, Duan, Dvorkin, Cora, Eggemeier, Alexander, Eisenstein, Daniel, Fan, Xiaohui, Ferreira, Pedro G., Font-Ribera, Andreu, Foreman, Simon, Garc��a-Bellido, Juan, Gerbino, Martina, Gluscevic, Vera, Gontcho, Satya Gontcho A, Green, Daniel, Guy, Julien, Hahn, ChangHoon, Hanany, Shaul, Handley, Will, Hathi, Nimish, Hawken, Adam J., Hern��ndez-Aguayo, C��sar, Hlo��ek, Ren��e, Huterer, Dragan, Ishak, Mustapha, Kamionkowski, Marc, Karagiannis, Dionysios, Keeley, Ryan E., Kehoe, Robert, Khatri, Rishi, Kim, Alex, Kneib, Jean-Paul, Kollmeier, Juna A., Kovetz, Ely D., Krause, Elisabeth, Krolewski, Alex, L'Huillier, Benjamin, Landriau, Martin, Levi, Michael, Liguori, Michele, Linder, Eric, Luki��, Zarija, de la Macorra, Axel, Plazas, Andr��s A., Marshall, Jennifer L., Martini, Paul, Masui, Kiyoshi, McDonald, Patrick, Meerburg, P. Daniel, Meyers, Joel, Mirbabayi, Mehrdad, Moustakas, John, Myers, Adam D., Palanque-Delabrouille, Nathalie, Newburgh, Laura, Newman, Jeffrey A., Niz, Gustavo, Padmanabhan, Hamsa, Palunas, Povilas, Percival, Will J., Piacentini, Francesco, Pieri, Matthew M., Piro, Anthony L., Prakash, Abhishek, Rhodes, Jason, Ross, Ashley J., Rossi, Graziano, Rudie, Gwen C., Samushia, Lado, Sasaki, Misao, Schaan, Emmanuel, Schlegel, David J., Schmittfull, Marcel, Schubnell, Michael, Sehgal, Neelima, Senatore, Leonardo, Seo, Hee-Jong, Shafieloo, Arman, Shan, Huanyuan, Simon, Joshua D., Simon, Sara, Slepian, Zachary, Slosar, An��e, Sridhar, Srivatsan, Stebbins, Albert, Escoffier, Stephanie, Switzer, Eric R., Tarl��, Gregory, Trodden, Mark, Uhlemann, Cora, Uren��a-L��pez, L. Arturo, Di Valentino, Eleonora, Vargas-Maga��a, M., Wang, Yi, Watson, Scott, White, Martin, Xu, Weishuang, Yu, Byeonghee, Zhao, Gong-Bo, Zheng, Yi, and Zhu, Hong-Ming

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics of Galaxies (astro-ph.GA), astro-ph.GA, astro-ph.CO, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics
Abstract

The expansion of the Universe is understood to have accelerated during two epochs: in its very first moments during a period of Inflation and much more recently, at $z < 1$, when Dark Energy is hypothesized to drive cosmic acceleration. The undiscovered mechanisms behind these two epochs represent some of the most important open problems in fundamental physics. The large cosmological volume at $2 < z < 5$, together with the ability to efficiently target high-$z$ galaxies with known techniques, enables large gains in the study of Inflation and Dark Energy. A future spectroscopic survey can test the Gaussianity of the initial conditions up to a factor of ~50 better than our current bounds, crossing the crucial theoretical threshold of $��(f_{NL}^{\rm local})$ of order unity that separates single field and multi-field models. Simultaneously, it can measure the fraction of Dark Energy at the percent level up to $z = 5$, thus serving as an unprecedented test of the standard model and opening up a tremendous discovery space., Science white paper submitted to the Astro2020 Decadal Survey

Published
2019

5. Dark Matter Science in the Era of LSST

Author

Bechtol, Keith, Drlica-Wagner, Alex, Abazajian, Kevork N., Abidi, Muntazir, Adhikari, Susmita, Ali-Haïmoud, Yacine, Annis, James, Ansarinejad, Behzad, Armstrong, Robert, Asorey, Jacobo, Baccigalupi, Carlo, Banerjee, Arka, Banik, Nilanjan, Bennett, Charles, Beutler, Florian, Bird, Simeon, Birrer, Simon, Biswas, Rahul, Biviano, Andrea, Blazek, Jonathan, Boddy, Kimberly K., Bonaca, Ana, Borrill, Julian, Bose, Sownak, Bovy, Jo, Frye, Brenda, Brooks, Alyson M., Buckley, Matthew R., Buckley-Geer, Elizabeth, Bulbul, Esra, Burchat, Patricia R., Burgess, Cliff, Calore, Francesca, Caputo, Regina, Castorina, Emanuele, Chang, Chihway, Chapline, George, Charles, Eric, Chen, Xingang, Clowe, Douglas, Cohen-Tanugi, Johann, Comparat, Johan, Croft, Rupert Ac, Cuoco, Alessandro, Cyr-Racine, Francis-Yan, D Amico, Guido, Davis, Tamara M., Dawson, William A., Macorra, Axel La, Valentino, Eleonora Di, Rivero, Ana Díaz, Digel, Seth, Dodelson, Scott, Doré, Olivier, Dvorkin, Cora, Eckner, Christopher, Ellison, John, Erkal, Denis, Farahi, Arya, Fassnacht, Christopher D., Ferreira, Pedro G., Flaugher, Brenna, Foreman, Simon, Friedrich, Oliver, Frieman, Joshua, García-Bellido, Juan, Gawiser, Eric, Gerbino, Martina, Maurizio Giannotti, Gill, Mandeep Ss, Gluscevic, Vera, Golovich, Nathan, Gontcho, Satya Gontcho A., González-Morales, Alma X., Grin, Daniel, Gruen, Daniel, Hearin, Andrew P., Hendel, David, Hezaveh, Yashar D., Hirata, Christopher M., Hložek, Renee, Horiuchi, Shunsaku, Jain, Bhuvnesh, Jee, M. James, Jeltema, Tesla E., Kamionkowski, Marc, Kaplinghat, Manoj, Keeley, Ryan E., Keeton, Charles R., Khatri, Rishi, Koposov, Sergey E., Koushiappas, Savvas M., Kovetz, Ely D., Lahav, Ofer, Lam, Casey, Lee, Chien-Hsiu, Li, Ting S., Liguori, Michele, Lin, Tongyan, Lisanti, Mariangela, Loverde, Marilena, Lu, Jessica R., Mandelbaum, Rachel, Mao, Yao-Yuan, Mcdermott, Samuel D., Mcnanna, Mitch, Medford, Michael, Meerburg, P. Daniel, Meyer, Manuel, Mirbabayi, Mehrdad, Mishra-Sharma, Siddharth, Marc, Moniez, More, Surhud, Moustakas, John, Muñoz, Julian B., Murgia, Simona, Myers, Adam D., Nadler, Ethan O., Necib, Lina, Newburgh, Laura, Newman, Jeffrey A., Nord, Brian, Nourbakhsh, Erfan, Nuss, Eric, O Connor, Paul, Pace, Andrew B., Padmanabhan, Hamsa, Palmese, Antonella, Peiris, Hiranya V., Peter, Annika Hg, Piacentni, Francesco, Piacentini, Francesco, Plazas, Andrés, Polin, Daniel A., Prakash, Abhishek, Prescod-Weinstein, Chanda, Read, Justin I., Ritz, Steven, Robertson, Brant E., Rose, Benjamin, Rosenfeld, Rogerio, Rossi, Graziano, Samushia, Lado, Sánchez, Javier, Sánchez-Conde, Miguel A., Schaan, Emmanuel, Sehgal, Neelima, Senatore, Leonardo, Seo, Hee-Jong, Shafieloo, Arman, Shan, Huanyuan, Shipp, Nora, Simon, Joshua D., Simon, Sara, Slatyer, Tracy R., Slosar, Anže, Sridhar, Srivatsan, Stebbins, Albert, Straniero, Oscar, Strigari, Louis E., Tait, Tim Mp, Tollerud, Erik, Troxel, Ma, Tyson, J. Anthony, Uhlemann, Cora, Urenña-López, L. Arturo, Verma, Aprajita, Vilalta, Ricardo, Walter, Christopher W., Wang, Mei-Yu, Watson, Scott, Wechsler, Risa H., Wittman, David, Xu, Weishuang, Yanny, Brian, Young, Sam, Yu, Hai-Bo, Zaharijas, Gabrijela, Zentner, Andrew R., Zuntz, Joe, Laboratoire d'Annecy-le-Vieux de Physique Théorique (LAPTH), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de l'Accélérateur Linéaire (LAL), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and HEP, INSPIRE

Subjects
Astrophysics and Astronomy, Cosmology and Nongalactic Astrophysics (astro-ph.CO), [PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex], Dark matter, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Compact star, 01 natural sciences, Standard Model, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Particle mass, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), astro-ph.HE, Physics, hep-ex, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, 13. Climate action, Fundamental physics, astro-ph.CO, [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, Particle Physics - Experiment, dark matter: parameter space, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Astrophysical observations currently provide the only robust, empirical measurements of dark matter. In the coming decade, astrophysical observations will guide other experimental efforts, while simultaneously probing unique regions of dark matter parameter space. This white paper summarizes astrophysical observations that can constrain the fundamental physics of dark matter in the era of LSST. We describe how astrophysical observations will inform our understanding of the fundamental properties of dark matter, such as particle mass, self-interaction strength, non-gravitational interactions with the Standard Model, and compact object abundances. Additionally, we highlight theoretical work and experimental/observational facilities that will complement LSST to strengthen our understanding of the fundamental characteristics of dark matter., 11 pages, 2 figures, Science Whitepaper for Astro 2020, more information at https://lsstdarkmatter.github.io

Published
2019

6. Scratches from the Past: Inflationary Archaeology through Features in the Power Spectrum of Primordial Fluctuations

Author

Slosar, Anze, Abazajian, Kevork N., Abidi, Muntazir, Adshead, Peter, Ahmed, Zeeshan, Alonso, David, Amin, Mustafa A., Ansarinejad, Behzad, Armstrong, Robert, Baccigalupi, Carlo, Bandura, Kevin, Battaglia, Nicholas, Bleem, Lindsey, Bond, J. Richard, Borrill, Julian, Bouchet, François R., Bull, Philip, Byrnes, Christian T., Carlstrom, John E., Castorina, Emanuele, Challinor, Anthony, Chen, Xingang, Cohn, J. D., Cooray, Asantha, Cyr-Racine, Francis-Yan, Demarteau, Marcel, Doré, Olivier, Douglass, Kelly A., Yutong, Duan, Dvorkin, Cora, Ellison, John, Essinger-Hileman, Tom, Fabbian, Giulio, Ferraro, Simone, Flauger, Raphael, Font-Ribera, Andreu, Foreman, Simon, García-Bellido, Juan, Gerbino, Martina, Gluscevic, Vera, Gontcho, A., Górski, Krzysztof M., Green, Daniel, Gudmundsson, Jon E., Gupta, Nikhel, Hanany, Shaul, Handley, Will, Hill, J. Colin, Hložek, Renée, Horiuchi, Shunsaku, Huterer, Dragan, Ishak, Mustapha, Johnson, Bradley, Kamionkowski, Marc, Karkare, Kirit S., Keeley, Ryan E., Khatri, Rishi, Kisner, Theodore, Kneib, Jean-Paul, Knox, Lloyd, Koushiappas, Savvas M., Kovetz, Ely D., Kazuya Koyama, Lahav, Ofer, Lattanzi, Massimiliano, Lee, Hayden, Liguori, Michele, Loverde, Marilena, Martini, Paul, Masui, Kiyoshi, Mcallister, Liam, Mcmahon, Jeff, Daniel Meerburg, P., Meyers, Joel, Motloch, Pavel, Mukherjee, Suvodip, Muñoz, Julian B., Myers, Adam D., Nagy, Johanna, Newburgh, Laura, Niemack, Michael D., Niz, Gustavo, Nomerotski, Andrei, Page, Lyman, Palma, Gonzalo A., Penna-Lima, Mariana, Percival, Will J., Piacentini, Francesco, Pierpaoli, Elena, Pogosian, Levon, Prakash, Abhishek, Pryke, Clement, Puglisi, Giuseppe, Stompor, Radek, Raveri, Marco, Ross, Ashley J., Rossi, Graziano, Ruhl, John, Samushia, Lado, Sasaki, Misao, Schaan, Emmanuel, Schillaci, Alessandro, Schmittfull, Marcel, Sehgal, Neelima, Senatore, Leonardo, Seo, Hee-Jong, Shafieloo, Arman, Shan, Huanyuan, Sherwin, Blake D., Silverstein, Eva, Simon, Sara, Starkman, Glenn, Suzuki, Aritoki, Switzer, Eric R., Basu Thakur, Ritoban, Timbie, Peter, Tolley, Andrew J., Tristram, Matthieu, Trodden, Mark, Umiltà, Caterina, Di Valentino, Eleonora, Vargas-Magaña, M., Vieregg, Abigail, Wallisch, Benjamin, Wands, David, Wang, Yi, Watson, Scott, Whitehorn, Nathan, Wu, W. L. K., Xianyu, Zhong-Zhi, Xu, Weishuang, Xu, Zhilei, Yasini, Siavash, Zaldarriaga, Matias, Zhao, Gong-Bo, Zhu, Ningfeng, Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de l'Accélérateur Linéaire (LAL), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
High Energy Physics - Theory, Cosmology and Nongalactic Astrophysics (astro-ph.CO), [PHYS.HTHE]Physics [physics]/High Energy Physics - Theory [hep-th], hep-th, fluctuation: primordial, FOS: Physical sciences, hep-ph, Astrophysics::Cosmology and Extragalactic Astrophysics, cosmic background radiation, inflation: model, power spectrum: primordial, inflation: nonminimal, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th), [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], astro-ph.CO, structure, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Inflation may provide unique insight into the physics at the highest available energy scales that cannot be replicated in any realistic terrestrial experiment. Features in the primordial power spectrum are generically predicted in a wide class of models of inflation and its alternatives, and are observationally one of the most overlooked channels for finding evidence for non-minimal inflationary models. Constraints from observations of the cosmic microwave background cover the widest range of feature frequencies, but the most sensitive constraints will come from future large-scale structure surveys that can measure the largest number of linear and quasi-linear modes., Comment: 5 pages + references, 1 figure; science white paper submitted to the Astro2020 decadal survey

Published
2019

7. Primordial Non-Gaussianity

Author

Meerburg, P. Daniel, Green, Daniel, Abidi, Muntazir, Amin, Mustafa A., Adshead, Peter, Ahmed, Zeeshan, Alonso, David, Ansarinejad, Behzad, Armstrong, Robert, Avila, Santiago, Baccigalupi, Carlo, Baldauf, Tobias, Ballardini, Mario, Bandura, Kevin, Bartolo, Nicola, Battaglia, Nicholas, Baumann, Daniel, Bavdhankar, Chetan, Bernal, José Luis, Beutler, Florian, Biagetti, Matteo, Bischoff, Colin, Blazek, Jonathan, Bond, J. Richard, Borrill, Julian, Bouchet, François R., Bull, Philip, Burgess, Cliff, Byrnes, Christian, Calabrese, Erminia, Carlstrom, John E., Castorina, Emanuele, Challinor, Anthony, Chang, Tzu-Ching, Chaves-Montero, Jonás, Chen, Xingang, Yèche, Christophe, Cooray, Asantha, Coulton, William, Crawford, Thomas, Chisari, Elisa, Cyr-Racine, Francis-Yan, D Amico, Guido, Bernardis, Paolo, La Macorra, Axel, Doré, Olivier, Duivenvoorden, Adri, Dunkley, Joanna, Dvorkin, Cora, Eggemeier, Alexander, Escoffier, Stephanie, Essinger-Hileman, Tom, Fasiello, Matteo, Ferraro, Simone, Flauger, Raphael, Font-Ribera, Andreu, Foreman, Simon, Friedrich, Oliver, García-Bellido, Juan, Gerbino, Martina, Gluscevic, Vera, Goon, Garrett, Górski, Krzysztof M., Gudmundsson, Jon E., Gupta, Nikhel, Hanany, Shaul, Handley, Will, Hawken, Adam J., Hill, J. Colin, Hirata, Christopher M., Hložek, Renée, Holder, Gilbert, Huterer, Dragan, Kamionkowski, Marc, Kirit Karkare, Keeley, Ryan E., Kinney, William, Kisner, Theodore, Kneib, Jean-Paul, Knox, Lloyd, Koushiappas, Savvas M., Kovetz, Ely D., Koyama, Kazuya, L Huillier, Benjamin, Lahav, Ofer, Lattanzi, Massimiliano, Lee, Hayden, Liguori, Michele, Loverde, Marilena, Madhavacheril, Mathew, Maldacena, Juan, Marsh, M. C. David, Masui, Kiyoshi, Matarrese, Sabino, Mcallister, Liam, Mcmahon, Jeff, Mcquinn, Matthew, Meyers, Joel, Mirbabayi, Mehrdad, Moradinezhad Dizgah, Azadeh, Motloch, Pavel, Mukherjee, Suvodip, Muñoz, Julian B., Myers, Adam D., Nagy, Johanna, Naselsky, Pavel, Nati, Federico, Newburgh, Nicolis, Alberto, Niemack, Michael D., Niz, Gustavo, Nomerotski, Andrei, Page, Lyman, Pajer, Enrico, Padmanabhan, Hamsa, Palma, Gonzalo A., Peiris, Hiranya V., Percival, Will J., Piacentni, Francesco, Pimentel, Guilherme L., Pogosian, Levon, Prescod-Weinstein, Chanda, Pryke, Clement, Puglisi, Giuseppe, Racine, Benjamin, Stompor, Radek, Raveri, Marco, Remazeilles, Mathieu, Rocha, Graça, Ross, Ashley J., Rossi, Graziano, Ruhl, John, Sasaki, Misao, Schaan, Emmanuel, Schillaci, Alessandro, Schmittfull, Marcel, Sehgal, Neelima, Senatore, Leonardo, Seo, Hee-Jong, Shan, Huanyuan, Shandera, Sarah, Sherwin, Blake D., Silverstein, Eva, Simon, Sara, Slosar, Anze, Staggs, Suzanne, Starkman, Glenn, Stebbins, Albert, Suzuki, Aritoki, Switzer, Eric R., Timbie, Peter, Tolley, Andrew J., Tomasi, Maurizio, Tristram, Matthieu, Trodden, Mark, Tsai, Yu-Dai, Uhlemann, Cora, Umiltà, Caterina, Engelen, Alexander, Vargas-Magaña, M., Vieregg, Abigail, Wallisch, Benjamin, Wands, David, Wandelt, Benjamin, Wang, Yi, Watson, Scott, Wise, Mark, Wu, W. L. K., Xianyu, Zhong-Zhi, Xu, Weishuang, Yasini, Siavash, Young, Sam, Yutong, Duan, Zaldarriaga, Matias, Zemcov, Michael, Zhao, Gong-Bo, Zheng, Yi, and Zhu, Ningfeng

Subjects
High Energy Physics - Theory, Cosmology and Nongalactic Astrophysics (astro-ph.CO), High Energy Physics - Theory (hep-th), FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Our current understanding of the Universe is established through the pristine measurements of structure in the cosmic microwave background (CMB) and the distribution and shapes of galaxies tracing the large scale structure (LSS) of the Universe. One key ingredient that underlies cosmological observables is that the field that sources the observed structure is assumed to be initially Gaussian with high precision. Nevertheless, a minimal deviation from Gaussianityis perhaps the most robust theoretical prediction of models that explain the observed Universe; itis necessarily present even in the simplest scenarios. In addition, most inflationary models produce far higher levels of non-Gaussianity. Since non-Gaussianity directly probes the dynamics in the early Universe, a detection would present a monumental discovery in cosmology, providing clues about physics at energy scales as high as the GUT scale., Comment: 5 pages + references; Submitted to the Astro2020 call for science white papers. This version: fixed author list

Published
2019
Full Text
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8. Non-Bunch-Davies Anisotropy

Author

Chen, Xingang and Wang, Yi

Subjects
High Energy Physics - Theory, High Energy Physics - Phenomenology, Cosmology and Nongalactic Astrophysics (astro-ph.CO), High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th), FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Computer Science::Databases, General Relativity and Quantum Cosmology, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We introduce a generic mechanism that can extend the effects of relic anisotropies at the beginning of inflation to relatively much shorter scales in density perturbations. This is induced by non-Bunch-Davies states of the quantum fluctuations, and can show up in the non-oscillatory components of the density perturbations. This mechanism works for general forms of anisotropies, and, to illustrate it, we use an example of relic vector field. The detailed scale-dependence of these anisotropies can be used to probe the initial quantum state of our universe., 10 pages

Published
2013

9. In-in and $��N$ calculations of the bispectrum from non-attractor single-field inflation

Author

Chen, Xingang, Firouzjahi, Hassan, Komatsu, Eiichiro, Namjoo, Mohammad Hossein, and Sasaki, Misao

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), High Energy Physics - Theory (hep-th), FOS: Physical sciences
Abstract

In non-attractor single-field inflation models producing a scale-invariant power spectrum, the curvature perturbation on super-horizon scales grows as ${\cal R}\propto a^3$. This is so far the only known class of self-consistent single-field models with a Bunch-Davies initial state that can produce a large squeezed-limit bispectrum violating Maldacena's consistency relation. Given the importance of this result, we calculate the bispectrum with three different methods: using quantum field theory calculations in two different gauges, and classical calculations (the $��N$ formalism). All the results agree, giving the local-form bispectrum parameter of $f^{local}_{NL}=5(1+c_s^2)/(4c_s^2)$. This result is valid for arbitrary values of the speed of sound parameter, $c_s$, for a particular non-attractor model we consider in this paper., 19 pages, 3 figures

Published
2013
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10. Anomalous High Energy Dependence in Inflationary Density Perturbations

Author

Chen, Xingang and Wang, Yi

Subjects
High Energy Physics - Theory, General Relativity and Quantum Cosmology, High Energy Physics - Phenomenology, Cosmology and Nongalactic Astrophysics (astro-ph.CO), High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th), FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We study the contribution of spectator massive scalar fields to the inflationary density perturbations through the universal gravitational coupling. We find that such contribution has several remarkable properties: it does not decrease as the mass of the spectator field increases; it has a significant size and cannot be turned off by any adjustable parameters; and it applies to all massive scalars existed during inflation, making the overall effect unexpectedly large. As a result, the primordial density perturbations are anomalously sensitive to the high energy physics., 4 pages

Published
2012

11. CMBPol Mission Concept Study: Probing Inflation with CMB Polarization

Author

Baumann, Daniel, Jackson, Mark G., Adshead, Peter, Amblard, Alexandre, Ashoorioon, Amjad, Bartolo, Nicola, Bean, Rachel, Beltran, Maria, de Bernardis, Francesco, Bird, Simeon, Chen, Xingang, Chung, Daniel J. H., Colombo, Loris, Cooray, Asantha, Creminelli, Paolo, Dodelson, Scott, Dunkley, Joanna, Dvorkin, Cora, Easther, Richard, Finelli, Fabio, Flauger, Raphael, Hertzberg, Mark, Jones-Smith, Katherine, Kachru, Shamit, Kadota, Kenji, Khoury, Justin, Kinney, William H., Komatsu, Eiichiro, Krauss, Lawrence M., Lesgourgues, Julien, Liddle, Andrew, Liguori, Michele, Lim, Eugene, Linde, Andrei, Matarrese, Sabino, Mathur, Harsh, McAllister, Liam, Melchiorri, Alessandro, Nicolis, Alberto, Pagano, Luca, Peiris, Hiranya V., Peloso, Marco, Pogosian, Levon, Pierpaoli, Elena, Riotto, Antonio, Seljak, Uros, Senatore, Leonardo, Shandera, Sarah, Silverstein, Eva, Smith, Tristan, Vaudrevange, Pascal, Verde, Licia, Wandelt, Ben, Wands, David, Watson, Scott, Wyman, Mark, Yadav, Amit, Valkenburg, Wessel, and Zaldarriaga, Matias

Subjects
High Energy Physics - Theory, Astrophysics and Astronomy, General Relativity and Quantum Cosmology, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th), Astrophysics (astro-ph), FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics
Abstract

We summarize the utility of precise cosmic microwave background (CMB) polarization measurements as probes of the physics of inflation. We focus on the prospects for using CMB measurements to differentiate various inflationary mechanisms. In particular, a detection of primordial B-mode polarization would demonstrate that inflation occurred at a very high energy scale, and that the inflaton traversed a super-Planckian distance in field space. We explain how such a detection or constraint would illuminate aspects of physics at the Planck scale. Moreover, CMB measurements can constrain the scale-dependence and non-Gaussianity of the primordial fluctuations and limit the possibility of a significant isocurvature contribution. Each such limit provides crucial information on the underlying inflationary dynamics. Finally, we quantify these considerations by presenting forecasts for the sensitivities of a future satellite experiment to the inflationary parameters., 107 pages, 14 figures, 17 tables; Inflation Working Group contribution to the CMBPol Mission Concept Study; v2: typos fixed and references added

Published
2008

12. Inflationary trispectrum for models with large non-Gaussianities

Author

Chen, Xingang, Huang, Min-xin, and Shiu, Gary

Subjects
High Energy Physics - Theory, Physics, Inflation (cosmology), Nuclear and High Energy Physics, 010308 nuclear & particles physics, Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Inflaton, Astrophysics, 01 natural sciences, Cosmology, High Energy Physics - Phenomenology, General Relativity and Quantum Cosmology, High Energy Physics - Phenomenology (hep-ph), Classical mechanics, High Energy Physics - Theory (hep-th), 0103 physical sciences, C++ string handling, Inflationary epoch, Statistical physics, Trispectrum, Quantum field theory, 010303 astronomy & astrophysics, Bispectrum
Abstract

We compute the leading order contribution to the four-point function of the primordial curvature perturbation in a class of single field models where the inflationary Lagrangian is a general function of the inflaton and its first derivative. This class of models includes string motivated inflationary models such as DBI inflation. We find that the trispectrum for some range of parameters could potentially be observed in future experiments. Moreover, the trispectrum can distinguish DBI inflation from other inflation models with large non-Gaussianities which typically have a similar bispectrum. We also derive a set of consistency conditions for n-point functions of the primordial curvature perturbation in single field inflation, generalizing Maldacena's result for 3-point functions., v2: 5 pages, journal version. v3, v4: formulae for the momentum dependence of trispectrum corrected, main conclusions remain unchanged, this version supersedes the journal version. v5: minor revision with an added reference

Published
2006
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13. Running Non-Gaussianities in DBI Inflation

Author

Chen, Xingang

Subjects
High Energy Physics - Theory, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th), Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics
Abstract

We study the non-Gaussianity in the simplest infrared (IR) model of the DBI inflation. We show that the non-Gaussianity in such a model is compatible with the current observational bound, and is within the sensitivity of future experiments. We also discuss the scale dependence of the non-Gaussianity. In the DBI inflation, such a feature can be used as a probe to the properties of the background geometry of the extra dimensions or internal space., 17 pages; v3, a numerical correction in f_NL, references added, PRD version

Published
2005

14. ADHMN boundary conditions from removing monopoles

Author

Chen, Xingang and Weinberg, Erick J.

Subjects
High Energy Physics - Theory, High Energy Physics::Theory, High Energy Physics - Theory (hep-th), High Energy Physics::Lattice, FOS: Physical sciences
Abstract

Boundary conditions play an important role in the ADHMN construction of BPS monopole solutions. In this paper we show how different types of boundary conditions can be related to each other by removing monopoles to spatial infinity. In particular, we use this method to show how the jumping data naturally emerge. The results can be interpreted in the D-brane picture and provide a better understanding of the derivation of the ADHMN construction from D-branes. We comment briefly on the cases with non-Abelian unbroken symmetry and massless monopoles., 37 pages, 6 figures

Published
2002

15. Inflation: Theory and Observations

Author

Achúcarro, Ana, Biagetti, Matteo, Matteo Braglia, Cabass, Giovanni, Caldwell, Robert, Castorina, Emanuele, Chen, Xingang, Coulton, William, Flauger, Raphael, Fumagalli, Jacopo, Ivanov, Mikhail M., Lee, Hayden, Maleknejad, Azadeh, Meerburg, P. Daniel, Dizgah, Azadeh Moradinezhad, Palma, Gonzalo A., Pimentel, Guilherme L., Renaux-Petel, Sébastien, Wallisch, Benjamin, Wandelt, Benjamin D., Witkowski, Lukas T., and Wu, W. L. Kimmy

Subjects
High Energy Physics - Theory, Astrophysics and Astronomy, Cosmology and Nongalactic Astrophysics (astro-ph.CO), hep-th, FOS: Physical sciences, hep-ph, Astrophysics::Cosmology and Extragalactic Astrophysics, High Energy Physics - Phenomenology, General Relativity and Quantum Cosmology, High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th), astro-ph.CO, Particle Physics - Theory, Astrophysics - Cosmology and Nongalactic Astrophysics, Particle Physics - Phenomenology
Abstract

Cosmic inflation provides a window to the highest energy densities accessible in nature, far beyond those achievable in any realistic terrestrial experiment. Theoretical insights into the inflationary era and its observational probes may therefore shed unique light on the physical laws underlying our universe. This white paper describes our current theoretical understanding of the inflationary era, with a focus on the statistical properties of primordial fluctuations. In particular, we survey observational targets for three important signatures of inflation: primordial gravitational waves, primordial non-Gaussianity and primordial features. With the requisite advancements in analysis techniques, the tremendous increase in the raw sensitivities of upcoming and planned surveys will translate to leaps in our understanding of the inflationary paradigm and could open new frontiers for cosmology and particle physics. The combination of future theoretical and observational developments therefore offer the potential for a dramatic discovery about the nature of cosmic acceleration in the very early universe and physics on the smallest scales., Contribution to Snowmass 2021; 103 pages, 8 figures, 378 endorsers; v2: minor changes

16. Messengers from the Early Universe: Cosmic Neutrinos and Other Light Relics

Author

Green, Daniel, Amin, Mustafa A., Meyers, Joel, Wallisch, Benjamin, Abazajian, Kevork N., Abidi, Muntazir, Adshead, Peter, Ahmed, Zeeshan, Ansarinejad, Behzad, Armstrong, Robert, Baccigalupi, Carlo, Bandura, Kevin, Barron, Darcy, Battaglia, Nicholas, Baumann, Daniel, Bechtol, Keith, Bennett, Charles, Benson, Bradford, Beutler, Florian, Bischoff, Colin, Bleem, Lindsey, Richard Bond, J., Borrill, Julian, Buckley-Geer, Elizabeth, Burgess, Cliff, Carlstrom, John E., Castorina, Emanuele, Challinor, Anthony, Chen, Xingang, Cooray, Asantha, Coulton, William, Craig, Nathaniel, Crawford, Thomas, Cyr-Racine, Francis-Yan, D Amico, Guido, Demarteau, Marcel, Doré, Olivier, Yutong, Duan, Dunkley, Joanna, Dvorkin, Cora, Ellison, John, Engelen, Alexander, Escoffier, Stephanie, Essinger-Hileman, Tom, Fabbian, Giulio, Filippini, Jeffrey, Flauger, Raphael, Foreman, Simon, Fuller, George, Garcia, Marcos A. G., García-Bellido, Juan, Gerbino, Martina, Gluscevic, Vera, Gontcho A Gontcho, Satya, Górski, Krzysztof M., Grin, Daniel, Grohs, Evan, Gudmundsson, Jon E., Hanany, Shaul, Handley, Will, Colin Hill, J., Hirata, Christopher M., Hložek, Renée, Holder, Gilbert, Horiuchi, Shunsaku, Huterer, Dragan, Kadota, Kenji, Kamionkowski, Marc, Keeley, Ryan E., Khatri, Rishi, Kisner, Theodore, Kneib, Jean-Paul, Knox, Lloyd, Koushiappas, Savvas M., Kovetz, Ely D., L Huillier, Benjamin, Lahav, Ofer, Lattanzi, Massimiliano, Lee, Hayden, Liguori, Michele, Lin, Tongyan, Loverde, Marilena, Madhavacheril, Mathew, Masui, Kiyoshi, Mcmahon, Jeff, Mcquinn, Matthew, Daniel Meerburg, P., Mirbabayi, Mehrdad, Motloch, Pavel, Mukherjee, Suvodip, Munõz, Julian B., Nagy, Johanna, Newburgh, Laura, Niemack, Michael D., Nomerotski, Andrei, Page, Lyman, Piacentni, Francesco, Pierpaoli, Elena, Pogosian, Levon, Pryke, Clement, Puglisi, Giuseppe, Stompor, Radek, Raveri, Marco, Reichardt, Christian L., Rose, Benjamin, Rossi, Graziano, Ruhl, John, Schaan, Emmanuel, Schubnell, Michael, Schutz, Katelin, Sehgal, Neelima, Senatore, Leonardo, Seo, Hee-Jong, Sherwin, Blake D., Simon, Sara, Slosar, Anže, Staggs, Suzanne, Albert Stebbins, Suzuki, Aritoki, Switzer, Eric R., Timbie, Peter, Tristram, Matthieu, Trodden, Mark, Tsai, Yu-Dai, Umiltà, Caterina, Di Valentino, Eleonora, Vargas-Magaña, M., Vieregg, Abigail, Watson, Scott, Weiler, Thomas, Whitehorn, Nathan, Wu, W. L. K., Xu, Weishuang, Xu, Zhilei, Yasini, Siavash, Zaldarriaga, Matias, Zhao, Gong-Bo, Zhu, Ningfeng, Zuntz, Joe, Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de l'Accélérateur Linéaire (LAL), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), and HEP, INSPIRE

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), long-lived, gravitation: effect, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, cosmic background radiation, High Energy Physics - Phenomenology (hep-ph), time: reheating, relic density, new physics, High Energy Physics::Phenomenology, photon, gravitational radiation, hep-ph, neutrino: sterile, boundary condition, [PHYS.HPHE] Physics [physics]/High Energy Physics - Phenomenology [hep-ph], High Energy Physics - Phenomenology, gravitational radiation: emission, axion, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], astro-ph.CO, [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], neutrino: decoupling, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The hot dense environment of the early universe is known to have produced large numbers of baryons, photons, and neutrinos. These extreme conditions may have also produced other long-lived species, including new light particles (such as axions or sterile neutrinos) or gravitational waves. The gravitational effects of any such light relics can be observed through their unique imprint in the cosmic microwave background (CMB), the large-scale structure, and the primordial light element abundances, and are important in determining the initial conditions of the universe. We argue that future cosmological observations, in particular improved maps of the CMB on small angular scales, can be orders of magnitude more sensitive for probing the thermal history of the early universe than current experiments. These observations offer a unique and broad discovery space for new physics in the dark sector and beyond, even when its effects would not be visible in terrestrial experiments or in astrophysical environments. A detection of an excess light relic abundance would be a clear indication of new physics and would provide the first direct information about the universe between the times of reheating and neutrino decoupling one second later., 5 pages + references; 1 figure; science white paper submitted to the Astro2020 decadal survey

17. Snowmass Theory Frontier: Astrophysics and Cosmology

Author

Green, Daniel, Ruderman, Joshua T., Safdi, Benjamin R., Shelton, Jessie, Achucarro, Ana, Adshead, Peter, Akrami, Yashar, Baryakhtar, Masha, Baumann, Daniel, Berlin, Asher, Blinov, Nikita, Boddy, Kimberly K., Buschmann, Malte, Cabass, Giovanni, Caldwell, Robert, Castorina, Emanuele, Chen, Thomas Y., Chen, Xingang, Coulton, William, Croon, Djuna, Yanou Cui, Curtin, David, Cyr-Racine, Francis-Yan, Dessert, Christopher, Dienes, Keith R., Draper, Patrick, Du, Peizhi, Ellis, Sebastian A. R., Essig, Rouven, Flauger, Raphael, Fong, Chee Sheng, Foster, Joshua W., Fumagalli, Jacopo, Harigaya, Keisuke, Horiuchi, Shunsaku, Ivanov, Mikhail M., Kahn, Yonatan, Knapen, Simon, Leane, Rebecca K., Lee, Hayden, Lentz, Erik W., Lewandowski, Matthew, Lisanti, Mariangela, Long, Andrew J., Loverde, Marilena, Maleknejad, Azadeh, Mcallister, Liam, Mcdermott, Samuel D., Mcgehee, Robert, Meerburg, P. Daniel, Meyers, Joel, Dizgah, Azadeh Moradinezhad, Münchmeyer, Moritz, Outmezguine, Nadav Joseph, Pajer, Enrico, Palma, Gonzalo A., Parikh, Aditya, Park, Jong-Chul, Peter, Annika H. G., Pimentel, Guilherme L., Renaux-Petel, Sébastien, Rodd, Nicholas L., Shakya, Bibhushan, Shiu, Gary, Silverstein, Eva, Simonovic, Marko, Singh, Rajeev, Sleight, Charlotte, Takhistov, Volodymyr, Tanedo, Philip, Taronna, Massimo, Thomas, Brooks, Toro, Natalia, Tsai, Yu-Dai, Vitagliano, Edoardo, Vogelsberger, Mark, Wallisch, Benjamin, Wandelt, Benjamin D., Wechsler, Risa H., Weniger, Christoph, Wu, W. L. Kimmy, Xu, Weishuang Linda, Yamada, Masaki, Yu, Hai-Bo, Zhang, Zhengkang, Zhong, Yi-Ming, and Zurek, Kathryn

Subjects
High Energy Physics - Theory, High Energy Physics - Phenomenology, Astrophysics and Astronomy, High Energy Physics - Phenomenology (hep-ph), Cosmology and Nongalactic Astrophysics (astro-ph.CO), High Energy Physics - Theory (hep-th), hep-th, astro-ph.CO, FOS: Physical sciences, hep-ph, Particle Physics - Theory, Astrophysics - Cosmology and Nongalactic Astrophysics, Particle Physics - Phenomenology
Abstract

We summarize progress made in theoretical astrophysics and cosmology over the past decade and areas of interest for the coming decade. This Report is prepared as the TF09 "Astrophysics and Cosmology" topical group summary for the Theory Frontier as part of the Snowmass 2021 process., Comment: 57 pages

18. Questions on calculation of primordial power spectrum with large spikes: the resonance model case

Author

Inomata, Keisuke, Braglia, Matteo, Chen, Xingang, and Renaux-Petel, Sébastien

Subjects
High Energy Physics - Phenomenology, Cosmology and Nongalactic Astrophysics (astro-ph.CO), High Energy Physics - Phenomenology (hep-ph), FOS: Physical sciences, Astronomy and Astrophysics, General Relativity and Quantum Cosmology (gr-qc), General Relativity and Quantum Cosmology, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Inflationary models predicting a scale-dependent large amplification of the density perturbations have recently attracted a lot of attention because the amplified perturbations can seed a sizable amount of primordial black holes (PBHs) and stochastic background of gravitational waves (GWs). While the power spectra in these models are computed based on the linear equation of motion, it is not obvious whether loop corrections are negligible when such a large amplification occurs during inflation. In this paper, as a first step to discuss the loop corrections in such models, we use the in-in formalism and calculate the one-loop scalar power spectrum numerically and analytically in an illustrative model where the density perturbations are resonantly amplified due to oscillatory features in the inflaton potential. Our calculation is technically new in that the amplified perturbations are numerically taken into account in the in-in formalism for the first time. In arriving at our analytical estimates, we highlight the role that the Wronskian condition of perturbations, automatically satisfied in our model, plays in obtaining the correct estimates. We also discuss the necessary conditions for subdominant loop corrections in this model. We find that, for the typical parameter space leading to the $\mathcal O(10^7)$ amplification of the power spectrum required for a sufficient PBH production, the one-loop power spectrum dominates over the tree-level one, indicating the breakdown of the perturbation theory., Comment: 42 pages, 14 figures, v3: An error in the equation of the two-vertex contribution corrected. Accordingly, the splitting of the two-vertex contribution changed and Appendix B added. The final one-loop power spectrum becomes smaller than the previous results, whereas the main conclusion (the typical oscillatory models lead to dominant loop power spectra) is unchanged

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