Pub Date : 2023-08-02DOI: 10.1146/annurev-nucl-102422-080857
M. Lugaro, M. Pignatari, R. Reifarth, M. Wiescher
Neutron captures produce the vast majority of abundances of elements heavier than iron in the Universe. Beyond the classical slow ( s) and rapid ( r) processes, there is observational evidence for neutron-capture processes that operate at neutron densities in between, at different distances from the valley of β stability. Here, we review the main properties of the s process within the general context of neutron-capture processes and the nuclear physics input required to investigate it. We describe massive stars and asymptotic giant branch stars as the s-process astrophysical sites and discuss the related physical uncertainties. We also present current observational evidence for the s process and beyond, which ranges from stellar spectroscopic observations to laboratory analysis of meteorites. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"The s Process and Beyond","authors":"M. Lugaro, M. Pignatari, R. Reifarth, M. Wiescher","doi":"10.1146/annurev-nucl-102422-080857","DOIUrl":"https://doi.org/10.1146/annurev-nucl-102422-080857","url":null,"abstract":"Neutron captures produce the vast majority of abundances of elements heavier than iron in the Universe. Beyond the classical slow ( s) and rapid ( r) processes, there is observational evidence for neutron-capture processes that operate at neutron densities in between, at different distances from the valley of β stability. Here, we review the main properties of the s process within the general context of neutron-capture processes and the nuclear physics input required to investigate it. We describe massive stars and asymptotic giant branch stars as the s-process astrophysical sites and discuss the related physical uncertainties. We also present current observational evidence for the s process and beyond, which ranges from stellar spectroscopic observations to laboratory analysis of meteorites. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8090,"journal":{"name":"Annual Review of Nuclear and Particle Science","volume":" ","pages":""},"PeriodicalIF":12.4,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44170705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-24DOI: 10.1146/annurev-nucl-110222-044046
Bai-Cian Ke, J. Koponen, Hai-Bo Li, Yangheng Zheng
We present a comprehensive review of purely leptonic and semileptonic decays of D0(+),[Formula: see text], and charmed baryons (including [Formula: see text], Ξ c, and Ω c). The precise studies of these decays help deepen our understanding and knowledge of quantum chromodynamics via measuring decay constants and form factors, and test the Standard Model through examining the unitarity of the Cabibbo–Kobayashi–Maskawa matrix and lepton flavor universality. We give an overview of the theoretical and experimental tools before discussing the recent progress. The data sets collected by the Beijing Spectrometer III (BESIII) near the production thresholds of [Formula: see text], and [Formula: see text]offer important opportunities for studies of charm physics. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Recent Progress in Leptonic and Semileptonic Decays of Charmed Hadrons","authors":"Bai-Cian Ke, J. Koponen, Hai-Bo Li, Yangheng Zheng","doi":"10.1146/annurev-nucl-110222-044046","DOIUrl":"https://doi.org/10.1146/annurev-nucl-110222-044046","url":null,"abstract":"We present a comprehensive review of purely leptonic and semileptonic decays of D0(+),[Formula: see text], and charmed baryons (including [Formula: see text], Ξ c, and Ω c). The precise studies of these decays help deepen our understanding and knowledge of quantum chromodynamics via measuring decay constants and form factors, and test the Standard Model through examining the unitarity of the Cabibbo–Kobayashi–Maskawa matrix and lepton flavor universality. We give an overview of the theoretical and experimental tools before discussing the recent progress. The data sets collected by the Beijing Spectrometer III (BESIII) near the production thresholds of [Formula: see text], and [Formula: see text]offer important opportunities for studies of charm physics. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8090,"journal":{"name":"Annual Review of Nuclear and Particle Science","volume":" ","pages":""},"PeriodicalIF":12.4,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48755050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-24DOI: 10.1146/annurev-nucl-112822-025357
Z. Cao, Song-zhan Chen, Ruo-Yu Liu, Rui-zhi Yang
Ultra-high-energy (UHE, >0.1 PeV) γ-ray astronomy is rapidly evolving into an expanding branch of γ-ray astronomy with the surprising discovery of 12 PeVatrons and the detection of a handful of photons above 1 PeV. Nearly all known celestial object types that have emissions in the TeV band are found also to emit UHE photons. UHE γ-rays have a well-defined horizon inside our Galaxy due to the absorption of infrared and cosmic microwave backgrounds in the Universe. In the last 30 years, traditional cosmic ray (CR) measurement techniques have enabled the detection of UHE γ-rays and opened the last observation window. For leptonic sources, UHE radiation is in the deep Klein–Nishina regime, which is largely suppressed. Therefore, UHE γ-ray detection will be helpful in locating and identifying hadronic radiation sources, tracing the historic pursuit for the origin of CRs around the knee of the spectrum. The Crab Nebula is the focus of attention with measured photon emissions up to 1 PeV. In the absence of hadronic processes, these emissions may indicate the existence of an extreme accelerator of e+ e−. Use of CR extensive air shower detection techniques broadens the field of view of the source observations, enabling measurement of UHE radiation surrounding the sources. These observations can probe the particle propagation inside and outside the accelerators and the subsequent injection/escape into the interstellar medium. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Ultra-High-Energy Gamma-Ray Astronomy","authors":"Z. Cao, Song-zhan Chen, Ruo-Yu Liu, Rui-zhi Yang","doi":"10.1146/annurev-nucl-112822-025357","DOIUrl":"https://doi.org/10.1146/annurev-nucl-112822-025357","url":null,"abstract":"Ultra-high-energy (UHE, >0.1 PeV) γ-ray astronomy is rapidly evolving into an expanding branch of γ-ray astronomy with the surprising discovery of 12 PeVatrons and the detection of a handful of photons above 1 PeV. Nearly all known celestial object types that have emissions in the TeV band are found also to emit UHE photons. UHE γ-rays have a well-defined horizon inside our Galaxy due to the absorption of infrared and cosmic microwave backgrounds in the Universe. In the last 30 years, traditional cosmic ray (CR) measurement techniques have enabled the detection of UHE γ-rays and opened the last observation window. For leptonic sources, UHE radiation is in the deep Klein–Nishina regime, which is largely suppressed. Therefore, UHE γ-ray detection will be helpful in locating and identifying hadronic radiation sources, tracing the historic pursuit for the origin of CRs around the knee of the spectrum. The Crab Nebula is the focus of attention with measured photon emissions up to 1 PeV. In the absence of hadronic processes, these emissions may indicate the existence of an extreme accelerator of e+ e−. Use of CR extensive air shower detection techniques broadens the field of view of the source observations, enabling measurement of UHE radiation surrounding the sources. These observations can probe the particle propagation inside and outside the accelerators and the subsequent injection/escape into the interstellar medium. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8090,"journal":{"name":"Annual Review of Nuclear and Particle Science","volume":" ","pages":""},"PeriodicalIF":12.4,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46573992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-17DOI: 10.1146/annurev-nucl-111422-040200
M. Reno
The cross sections for neutrino interactions with nucleons have been measured directly in accelerator experiments and through the zenith-angle and energy dependence of neutrino events at the IceCube Neutrino Observatory. Fluxes of high-energy neutrinos are produced at the Large Hadron Collider and by cosmic rays in the atmosphere. High-energy neutrinos also come from astrophysical and cosmic sources. The theory of neutrino interactions is reviewed. Current cross-section measurements and prospects for the future are discussed. The focus here is on neutrino interactions for energies larger than 1 TeV. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"High-Energy to Ultrahigh-Energy Neutrino Interactions","authors":"M. Reno","doi":"10.1146/annurev-nucl-111422-040200","DOIUrl":"https://doi.org/10.1146/annurev-nucl-111422-040200","url":null,"abstract":"The cross sections for neutrino interactions with nucleons have been measured directly in accelerator experiments and through the zenith-angle and energy dependence of neutrino events at the IceCube Neutrino Observatory. Fluxes of high-energy neutrinos are produced at the Large Hadron Collider and by cosmic rays in the atmosphere. High-energy neutrinos also come from astrophysical and cosmic sources. The theory of neutrino interactions is reviewed. Current cross-section measurements and prospects for the future are discussed. The focus here is on neutrino interactions for energies larger than 1 TeV. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8090,"journal":{"name":"Annual Review of Nuclear and Particle Science","volume":"488 ","pages":""},"PeriodicalIF":12.4,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41272207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-27DOI: 10.1146/annurev-nucl-111722-025122
Jingke Xu, P. Barbeau, Ziqing Hong
Detection of low-energy nuclear recoil events plays a central role in searches for weakly interacting massive particle (WIMP) dark matter interactions with atomic matter and studies of coherent neutrino scatters. Precise nuclear recoil calibration data allow the responses of these dark matter and neutrino detectors to be characterized and enable in situ evaluation of an experiment's sensitivity to anticipated signals. This article reviews the common methods for detection of nuclear recoil events and the wide variety of techniques that have been developed to calibrate detector response to nuclear recoils. We summarize the main experimental factors that are critical for accurate nuclear recoil calibrations, investigate mitigation strategies for different backgrounds and biases, and discuss how the presentation of calibration results can facilitate comparison between experiments. Lastly, we discuss the challenges for future nuclear recoil calibration efforts and the physics opportunities they may enable. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Detection and Calibration of Low-Energy Nuclear Recoils for Dark Matter and Neutrino Scattering Experiments","authors":"Jingke Xu, P. Barbeau, Ziqing Hong","doi":"10.1146/annurev-nucl-111722-025122","DOIUrl":"https://doi.org/10.1146/annurev-nucl-111722-025122","url":null,"abstract":"Detection of low-energy nuclear recoil events plays a central role in searches for weakly interacting massive particle (WIMP) dark matter interactions with atomic matter and studies of coherent neutrino scatters. Precise nuclear recoil calibration data allow the responses of these dark matter and neutrino detectors to be characterized and enable in situ evaluation of an experiment's sensitivity to anticipated signals. This article reviews the common methods for detection of nuclear recoil events and the wide variety of techniques that have been developed to calibrate detector response to nuclear recoils. We summarize the main experimental factors that are critical for accurate nuclear recoil calibrations, investigate mitigation strategies for different backgrounds and biases, and discuss how the presentation of calibration results can facilitate comparison between experiments. Lastly, we discuss the challenges for future nuclear recoil calibration efforts and the physics opportunities they may enable. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8090,"journal":{"name":"Annual Review of Nuclear and Particle Science","volume":" ","pages":""},"PeriodicalIF":12.4,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43776957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-27DOI: 10.1146/annurev-nucl-102020-101615
F. Lodovico, R. Patterson, M. Shiozawa, E. Worcester
Long-baseline neutrino oscillation experiments, which are among the largest neutrino experiments in the world, have extensive physics programs to make precision measurements of three-flavor oscillation parameters, search for physics beyond the Standard Model, and study neutrinos from astrophysical sources. In this article, experimental considerations, including oscillation phenomenology, detector and experiment design, and analysis strategies, are described, with a focus on the three-flavor oscillation measurements. Current and future experiments are discussed, and significant sources of systematic uncertainty, along with mitigation strategies, are emphasized as control of systematic uncertainty is critical for success in precise measurement of long-baseline oscillation parameters. This article is structured as a primer for those new to this area of experimental work. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Experimental Considerations in Long-Baseline Neutrino Oscillation Measurements","authors":"F. Lodovico, R. Patterson, M. Shiozawa, E. Worcester","doi":"10.1146/annurev-nucl-102020-101615","DOIUrl":"https://doi.org/10.1146/annurev-nucl-102020-101615","url":null,"abstract":"Long-baseline neutrino oscillation experiments, which are among the largest neutrino experiments in the world, have extensive physics programs to make precision measurements of three-flavor oscillation parameters, search for physics beyond the Standard Model, and study neutrinos from astrophysical sources. In this article, experimental considerations, including oscillation phenomenology, detector and experiment design, and analysis strategies, are described, with a focus on the three-flavor oscillation measurements. Current and future experiments are discussed, and significant sources of systematic uncertainty, along with mitigation strategies, are emphasized as control of systematic uncertainty is critical for success in precise measurement of long-baseline oscillation parameters. This article is structured as a primer for those new to this area of experimental work. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8090,"journal":{"name":"Annual Review of Nuclear and Particle Science","volume":" ","pages":""},"PeriodicalIF":12.4,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45787044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-07DOI: 10.1146/annurev-nucl-101920-013011
S. Knapen, S. Lowette
This article is a pedagogical review of searches for long-lived particles at the LHC. It is primarily aimed at experimentalists and theorists seeking to initiate and/or deepen their research in this field. We cover the general theoretical motivation and some example models, the main experimental techniques employed in searches for long-lived particles, and some of the important subtleties involved in estimating signal efficiencies and background rates. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"A Guide to Hunting Long-Lived Particles at the LHC","authors":"S. Knapen, S. Lowette","doi":"10.1146/annurev-nucl-101920-013011","DOIUrl":"https://doi.org/10.1146/annurev-nucl-101920-013011","url":null,"abstract":"This article is a pedagogical review of searches for long-lived particles at the LHC. It is primarily aimed at experimentalists and theorists seeking to initiate and/or deepen their research in this field. We cover the general theoretical motivation and some example models, the main experimental techniques employed in searches for long-lived particles, and some of the important subtleties involved in estimating signal efficiencies and background rates. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8090,"journal":{"name":"Annual Review of Nuclear and Particle Science","volume":"1 1","pages":""},"PeriodicalIF":12.4,"publicationDate":"2022-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41666866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-30DOI: 10.1146/annurev-nucl-112822-031317
S. Cao, G. Qin
The study of high-energy heavy-ion collisions at the Relativistic Heavy Ion Collider and the Large Hadron Collider has evolved from a qualitative understanding to the precise extraction of the properties of the quantum chromodynamics medium at extremely high temperatures. Jet quenching has offered unique insights into the transport properties of the quark–gluon plasma (QGP) created in these energetic collisions. Apart from medium modification of jets, jet-induced medium excitation constitutes another crucial aspect of jet–QGP interaction and is indispensable in understanding the soft components of jets. We review recent theoretical and phenomenological developments regarding medium response to jet energy loss, including an overview of both weakly and strongly coupled approaches for describing the thermalization and propagation of energy deposition from jets, effects of medium response on jet observables, and exploration of its unique signatures in jet–hadron correlations. Jet-induced medium excitation is shown to be an essential component in probing the in-medium dynamics of jets and a critical step toward precise extraction of the QGP properties. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Medium Response and Jet–Hadron Correlations in Relativistic Heavy-Ion Collisions","authors":"S. Cao, G. Qin","doi":"10.1146/annurev-nucl-112822-031317","DOIUrl":"https://doi.org/10.1146/annurev-nucl-112822-031317","url":null,"abstract":"The study of high-energy heavy-ion collisions at the Relativistic Heavy Ion Collider and the Large Hadron Collider has evolved from a qualitative understanding to the precise extraction of the properties of the quantum chromodynamics medium at extremely high temperatures. Jet quenching has offered unique insights into the transport properties of the quark–gluon plasma (QGP) created in these energetic collisions. Apart from medium modification of jets, jet-induced medium excitation constitutes another crucial aspect of jet–QGP interaction and is indispensable in understanding the soft components of jets. We review recent theoretical and phenomenological developments regarding medium response to jet energy loss, including an overview of both weakly and strongly coupled approaches for describing the thermalization and propagation of energy deposition from jets, effects of medium response on jet observables, and exploration of its unique signatures in jet–hadron correlations. Jet-induced medium excitation is shown to be an essential component in probing the in-medium dynamics of jets and a critical step toward precise extraction of the QGP properties. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8090,"journal":{"name":"Annual Review of Nuclear and Particle Science","volume":" ","pages":""},"PeriodicalIF":12.4,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42435442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-08DOI: 10.1146/annurev-nucl-111422-024107
M. Kamionkowski, A. Riess
Over the past decade, the disparity between the value of the cosmic expansion rate determined directly from measurements of distance and redshift and that determined instead from the standard Lambda cold dark matter (ΛCDM) cosmological model, calibrated by measurements from the early Universe, has grown to a level of significance requiring a solution. Proposed systematic errors are not supported by the breadth of available data (and unknown errors untestable by lack of definition). Simple theoretical explanations for this Hubble tension that are consistent with the majority of the data have been surprisingly hard to come by, but in recent years, attention has focused increasingly on models that alter the early or pre-recombination physics of ΛCDM as the most feasible. Here, we describe the nature of this tension and emphasize recent developments on the observational side. We then explain why early-Universe solutions are currently favored and the constraints that any such model must satisfy. We discuss one workable example, early dark energy, and describe how it can be tested with future measurements. Given an assortment of more extended recent reviews on specific aspects of the problem, the discussion is intended to be fairly general and understandable to a broad audience. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"The Hubble Tension and Early Dark Energy","authors":"M. Kamionkowski, A. Riess","doi":"10.1146/annurev-nucl-111422-024107","DOIUrl":"https://doi.org/10.1146/annurev-nucl-111422-024107","url":null,"abstract":"Over the past decade, the disparity between the value of the cosmic expansion rate determined directly from measurements of distance and redshift and that determined instead from the standard Lambda cold dark matter (ΛCDM) cosmological model, calibrated by measurements from the early Universe, has grown to a level of significance requiring a solution. Proposed systematic errors are not supported by the breadth of available data (and unknown errors untestable by lack of definition). Simple theoretical explanations for this Hubble tension that are consistent with the majority of the data have been surprisingly hard to come by, but in recent years, attention has focused increasingly on models that alter the early or pre-recombination physics of ΛCDM as the most feasible. Here, we describe the nature of this tension and emphasize recent developments on the observational side. We then explain why early-Universe solutions are currently favored and the constraints that any such model must satisfy. We discuss one workable example, early dark energy, and describe how it can be tested with future measurements. Given an assortment of more extended recent reviews on specific aspects of the problem, the discussion is intended to be fairly general and understandable to a broad audience. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 73 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8090,"journal":{"name":"Annual Review of Nuclear and Particle Science","volume":" ","pages":""},"PeriodicalIF":12.4,"publicationDate":"2022-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48100980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-26DOI: 10.1146/annurev-nucl-121521-051029
N. Fomin, J. Fry, R. Pattie, G. Greene
Low-energy neutrons have been a useful probe in fundamental physics studies for more than 70 years. With advances in accelerator technology, many new sources are spallation based. These new, high-flux facilities are becoming the sites for many next-generation fundamental neutron physics experiments. In this review, we present an overview of the sources and the current and upcoming fundamental neutron physics programs.
{"title":"Fundamental Neutron Physics at Spallation Sources","authors":"N. Fomin, J. Fry, R. Pattie, G. Greene","doi":"10.1146/annurev-nucl-121521-051029","DOIUrl":"https://doi.org/10.1146/annurev-nucl-121521-051029","url":null,"abstract":"Low-energy neutrons have been a useful probe in fundamental physics studies for more than 70 years. With advances in accelerator technology, many new sources are spallation based. These new, high-flux facilities are becoming the sites for many next-generation fundamental neutron physics experiments. In this review, we present an overview of the sources and the current and upcoming fundamental neutron physics programs.","PeriodicalId":8090,"journal":{"name":"Annual Review of Nuclear and Particle Science","volume":" ","pages":""},"PeriodicalIF":12.4,"publicationDate":"2022-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47403009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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