Pub Date : 2026-02-25DOI: 10.1088/1475-7516/2026/02/084
Thomas Konstandin, Anna-Malin Lemke, Andrea Mitridate and Enrico Perboni
Recent findings from several Pulsar Timing Array (PTA) collaborations point to the existence of a Gravitational Wave Background (GWB) at nanohertz frequencies. A key next step towards characterizing this signal and identifying its origin is to map the sky distribution of its power. Several strategies have been proposed to reconstruct this distribution using PTA data. In this work, we compare these different strategies to determine which one is best suited to detect GWB anisotropies of different topologies. We find that, for both localized and large-scale anisotropies, reconstruction methods based on pixel and radiometer maps are the most promising. However, in both scenarios, even the optimistically large anisotropic signals discussed in this work remain challenging to detect with near-future PTA sensitivities. For example, we find that for a GWB hotspot contributing to 80% of the GWB power in the second frequency bin, detection probabilities reach at most 𝒪(10%) for a PTA with noise properties comparable with the ones of the upcoming IPTA third data release. Finally, we consider the fundamental limitations that cosmic variance poses to these kinds of searches by deriving the smallest deviations from isotropy that could be detected by an idealized PTA with no experimental or pulsar noise.
{"title":"Prospects and limitations of PTAs anisotropy searches — the frequentist case","authors":"Thomas Konstandin, Anna-Malin Lemke, Andrea Mitridate and Enrico Perboni","doi":"10.1088/1475-7516/2026/02/084","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/084","url":null,"abstract":"Recent findings from several Pulsar Timing Array (PTA) collaborations point to the existence of a Gravitational Wave Background (GWB) at nanohertz frequencies. A key next step towards characterizing this signal and identifying its origin is to map the sky distribution of its power. Several strategies have been proposed to reconstruct this distribution using PTA data. In this work, we compare these different strategies to determine which one is best suited to detect GWB anisotropies of different topologies. We find that, for both localized and large-scale anisotropies, reconstruction methods based on pixel and radiometer maps are the most promising. However, in both scenarios, even the optimistically large anisotropic signals discussed in this work remain challenging to detect with near-future PTA sensitivities. For example, we find that for a GWB hotspot contributing to 80% of the GWB power in the second frequency bin, detection probabilities reach at most 𝒪(10%) for a PTA with noise properties comparable with the ones of the upcoming IPTA third data release. Finally, we consider the fundamental limitations that cosmic variance poses to these kinds of searches by deriving the smallest deviations from isotropy that could be detected by an idealized PTA with no experimental or pulsar noise.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"45 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147278962","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 : 2026-02-25DOI: 10.1088/1475-7516/2026/02/082
Raymond T. Co, Nicolas Fernandez, Akshay Ghalsasi, Keisuke Harigaya and Jessie Shelton
Despite stringent constraints from Big Bang Nucleosynthesis (BBN) and cosmic microwave background (CMB) observations, it is still possible for well-motivated particle physics models to substantially alter the cosmic expansion history between BBN and recombination. In this work we consider two different axion models that can realize a period of first matter domination, then kination, in this epoch. We perform fits to both primordial element abundances as well as CMB data and determine that up to a decade of late axion domination is allowed by these probes of the early universe. We establish the implications of late axion domination for the matter power spectrum on the scales 1/Mpc ≲ k ≲ 103/Mpc. Our `log' model predicts a relatively modest bump-like feature together with a small suppression relative to the standard ΛCDM predictions on either side of the enhancement. Our `two-field' model predicts a larger, plateau-like feature that realizes enhancements to the matter power spectrum of up to two orders of magnitude. These features have interesting implications for structure formation at the forefront of current detection capabilities.
尽管受到大爆炸核合成（BBN）和宇宙微波背景（CMB）观测的严格限制，但良好的粒子物理模型仍然有可能从本质上改变BBN和重组之间的宇宙膨胀历史。在这项工作中，我们考虑了两种不同的轴子模型，它们可以在这个时代实现首先是物质统治，然后是kinination的时期。我们对原始元素丰度和CMB数据进行了拟合，并确定这些早期宇宙探测器允许长达十年的晚期轴子支配。我们在1/Mpc > k > 103/Mpc的尺度上建立了晚期轴子支配对物质功率谱的影响。我们的“log”模型预测了一个相对适度的凹凸状特征，以及相对于增强两侧的标准ΛCDM预测的小抑制。我们的“双场”模型预测了一个更大的，类似于平台的特征，实现了物质功率谱高达两个数量级的增强。这些特征对当前探测能力前沿的结构形成具有有趣的含义。
{"title":"Enhanced matter power spectrum from axion kination after Big Bang nucleosynthesis","authors":"Raymond T. Co, Nicolas Fernandez, Akshay Ghalsasi, Keisuke Harigaya and Jessie Shelton","doi":"10.1088/1475-7516/2026/02/082","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/082","url":null,"abstract":"Despite stringent constraints from Big Bang Nucleosynthesis (BBN) and cosmic microwave background (CMB) observations, it is still possible for well-motivated particle physics models to substantially alter the cosmic expansion history between BBN and recombination. In this work we consider two different axion models that can realize a period of first matter domination, then kination, in this epoch. We perform fits to both primordial element abundances as well as CMB data and determine that up to a decade of late axion domination is allowed by these probes of the early universe. We establish the implications of late axion domination for the matter power spectrum on the scales 1/Mpc ≲ k ≲ 103/Mpc. Our `log' model predicts a relatively modest bump-like feature together with a small suppression relative to the standard ΛCDM predictions on either side of the enhancement. Our `two-field' model predicts a larger, plateau-like feature that realizes enhancements to the matter power spectrum of up to two orders of magnitude. These features have interesting implications for structure formation at the forefront of current detection capabilities.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"56 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147280040","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 : 2026-02-25DOI: 10.1088/1475-7516/2026/02/085
Yuan Shi, Pengjie Zhang, Zhao Chen, Jian Qin, Li Cui, Furen Deng and Ji Yao
Weak lensing mass-mapping from shear catalogs faces systematic challenges from survey masks and spatially varying noise. To overcome these issues and reconstruct unbiased convergence κ maps, we have constructed the AKRA (Accurate Kappa Reconstruction Algorithm), a prior-free and maximum-likelihood based analytical method. It has been validated for mock shear catalogs with a variety of survey masks. In this work, we present the first real-data application of the AKRA on the Subaru Hyper Suprime-Cam Year 1 (HSC Y1) data. We first validate AKRA using mock shear catalogs from the Kun simulation suite, with masks corresponding to the six HSC Y1 regions (GAMA09H, GAMA15H, HECTOMAP, VVDS, WIDE12H, and XMMLSS). The investigated statistics, including the lensing power spectrum, ⟨κ2⟩, ⟨κ3⟩, and the one-point probability distribution function of κ, are all unbiased. We then apply AKRA to the HSC Y1 shear catalog and provide reconstructed κ maps ready for subsequent scientific analyses.
{"title":"The first AKRA mass map reconstruction from HSC Y1 data","authors":"Yuan Shi, Pengjie Zhang, Zhao Chen, Jian Qin, Li Cui, Furen Deng and Ji Yao","doi":"10.1088/1475-7516/2026/02/085","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/085","url":null,"abstract":"Weak lensing mass-mapping from shear catalogs faces systematic challenges from survey masks and spatially varying noise. To overcome these issues and reconstruct unbiased convergence κ maps, we have constructed the AKRA (Accurate Kappa Reconstruction Algorithm), a prior-free and maximum-likelihood based analytical method. It has been validated for mock shear catalogs with a variety of survey masks. In this work, we present the first real-data application of the AKRA on the Subaru Hyper Suprime-Cam Year 1 (HSC Y1) data. We first validate AKRA using mock shear catalogs from the Kun simulation suite, with masks corresponding to the six HSC Y1 regions (GAMA09H, GAMA15H, HECTOMAP, VVDS, WIDE12H, and XMMLSS). The investigated statistics, including the lensing power spectrum, ⟨κ2⟩, ⟨κ3⟩, and the one-point probability distribution function of κ, are all unbiased. We then apply AKRA to the HSC Y1 shear catalog and provide reconstructed κ maps ready for subsequent scientific analyses.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"13 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147278963","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 : 2026-02-25DOI: 10.1088/1475-7516/2026/02/081
P.H.F. Arruda and S.D. Campos
We study phase-transition-like behavior in neutron stars using a simplified, piecewise equation of state that couples a modified van der Waals-type core to a polytropic crust. The model remains analytically tractable while still allowing for nonlinear density dependence. We impose thermodynamic and causal consistency conditions and determine the critical densities at which the curvature of the pressure-energy-density relation changes. In the non-relativistic limit, the generalized Lane-Emden equations describe a smooth core-crust transition layer. We integrate the Tolman-Oppenheimer-Volkoff equations across different (τ1,σ1) regimes, where these parameters encode thermal and interaction effects in the core. The resulting mass-radius sequences yield low neutron star masses (0.79-2.05) M⊙, and the chemical potential exhibits pronounced curvature changes often associated with phase-transition-like behavior at densities well above the matching point, while remaining smooth and monotonic and thus not signaling a genuine first-order phase transition. Our results show that analytic equation of state models can reproduce the key phenomenology of phase-transitions-like behavior and provide a controlled framework for exploring low-mass neutron star configurations.
{"title":"Low-mass neutron stars and effective phase transitions from a hybrid Van der Waals-polytropic equation of state","authors":"P.H.F. Arruda and S.D. Campos","doi":"10.1088/1475-7516/2026/02/081","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/081","url":null,"abstract":"We study phase-transition-like behavior in neutron stars using a simplified, piecewise equation of state that couples a modified van der Waals-type core to a polytropic crust. The model remains analytically tractable while still allowing for nonlinear density dependence. We impose thermodynamic and causal consistency conditions and determine the critical densities at which the curvature of the pressure-energy-density relation changes. In the non-relativistic limit, the generalized Lane-Emden equations describe a smooth core-crust transition layer. We integrate the Tolman-Oppenheimer-Volkoff equations across different (τ1,σ1) regimes, where these parameters encode thermal and interaction effects in the core. The resulting mass-radius sequences yield low neutron star masses (0.79-2.05) M⊙, and the chemical potential exhibits pronounced curvature changes often associated with phase-transition-like behavior at densities well above the matching point, while remaining smooth and monotonic and thus not signaling a genuine first-order phase transition. Our results show that analytic equation of state models can reproduce the key phenomenology of phase-transitions-like behavior and provide a controlled framework for exploring low-mass neutron star configurations.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"10 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147278960","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 : 2026-02-24DOI: 10.1088/1475-7516/2026/02/080
Alexander Steier, Shamik Ghosh and Jacques Delabrouille
The detection of primordial gravitational waves in Cosmic Microwave Background B-mode polarization observations requires accurate and robust subtraction of astrophysical contamination. We show, using a blind Spectral Matching Independent Component Analysis, that it is possible to infer unbiased estimates of the primordial B-mode signal from ground-based observations of a small patch of sky even for highly complex foreground contamination. This work, originally performed in the context of configuration studies for a future CMB-S4 observatory, is highly relevant for the analysis of observations by the current generation of CMB experiments.
{"title":"Unbiased primordial gravitational wave inference from the CMB with SMICA","authors":"Alexander Steier, Shamik Ghosh and Jacques Delabrouille","doi":"10.1088/1475-7516/2026/02/080","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/080","url":null,"abstract":"The detection of primordial gravitational waves in Cosmic Microwave Background B-mode polarization observations requires accurate and robust subtraction of astrophysical contamination. We show, using a blind Spectral Matching Independent Component Analysis, that it is possible to infer unbiased estimates of the primordial B-mode signal from ground-based observations of a small patch of sky even for highly complex foreground contamination. This work, originally performed in the context of configuration studies for a future CMB-S4 observatory, is highly relevant for the analysis of observations by the current generation of CMB experiments.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"104 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147278363","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 : 2026-02-24DOI: 10.1088/1475-7516/2026/02/079
Jiazheng Dou and Wen Zhao
Cosmic birefringence (CB) is a promising probe of parity-violating physics beyond the Standard Model, characterized by the rotation of the linear polarization plane of cosmic microwave background (CMB) photons. This effect, quantified by the birefringence angle β, generates non-zero EB and TB correlations that are otherwise absent in standard cosmology. However, instrumental miscalibration angles α can mimic this signal, necessitating a joint estimation approach. In this work, we forecast the sensitivity of the AliCPT experiment, combined with Planck HFI data, on constraining the isotropic CB angle using a semi-analytical maximum-likelihood method. We simulate observations under various foreground complexities, rotation angles, and scanning strategies, and demonstrate that AliCPT can achieve an uncertainty of σ(β) = 0.09∘ with one-year data, which will improve to 0.026∘ after four years' observations. We also find that neglecting or mismodeling the foreground EB correlation will introduce significant biases, which can be alleviated under a clean but small sky patch.
{"title":"Forecasts of constraining isotropic cosmic birefringence on AliCPT-1","authors":"Jiazheng Dou and Wen Zhao","doi":"10.1088/1475-7516/2026/02/079","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/079","url":null,"abstract":"Cosmic birefringence (CB) is a promising probe of parity-violating physics beyond the Standard Model, characterized by the rotation of the linear polarization plane of cosmic microwave background (CMB) photons. This effect, quantified by the birefringence angle β, generates non-zero EB and TB correlations that are otherwise absent in standard cosmology. However, instrumental miscalibration angles α can mimic this signal, necessitating a joint estimation approach. In this work, we forecast the sensitivity of the AliCPT experiment, combined with Planck HFI data, on constraining the isotropic CB angle using a semi-analytical maximum-likelihood method. We simulate observations under various foreground complexities, rotation angles, and scanning strategies, and demonstrate that AliCPT can achieve an uncertainty of σ(β) = 0.09∘ with one-year data, which will improve to 0.026∘ after four years' observations. We also find that neglecting or mismodeling the foreground EB correlation will introduce significant biases, which can be alleviated under a clean but small sky patch.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"338 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147278499","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 : 2026-02-23DOI: 10.1088/1475-7516/2026/02/074
Beatriz Hernández-Molinero, Raul Jimenez and Carlos Peña Garay
Low-energy neutrinos from the Cosmic Neutrino Background can be captured by objects in the sky containing β-unstable nuclei. Planets host such unstable isotopes capable of capturing relic neutrinos, although the resulting signals are extremely small. While detection with current technology remains challenging, the mechanism offers a novel astrophysical pathway to probe the CνB. Additionally, we investigate the conditions under which out-of-equilibrium neutrons in the outer layers of neutron stars could produce a potentially detectable signal through relic neutrino capture.
{"title":"Effects of the cosmic neutrino background capture on astrophysical objects","authors":"Beatriz Hernández-Molinero, Raul Jimenez and Carlos Peña Garay","doi":"10.1088/1475-7516/2026/02/074","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/074","url":null,"abstract":"Low-energy neutrinos from the Cosmic Neutrino Background can be captured by objects in the sky containing β-unstable nuclei. Planets host such unstable isotopes capable of capturing relic neutrinos, although the resulting signals are extremely small. While detection with current technology remains challenging, the mechanism offers a novel astrophysical pathway to probe the CνB. Additionally, we investigate the conditions under which out-of-equilibrium neutrons in the outer layers of neutron stars could produce a potentially detectable signal through relic neutrino capture.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"96 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146777168","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 : 2026-02-23DOI: 10.1088/1475-7516/2026/02/075
Jae Hyeok Chang, Peizhi Du, Subhajit Ghosh and Soubhik Kumar
Dark radiation (DR) is ubiquitous in physics beyond the Standard Model (SM), and its interactions with the SM and dark matter (DM) lead to a variety of interesting effects on cosmological observables. However, even in scenarios where DR is `secluded', i.e., only gravitationally interacting with SM and DM, it can leave discernible signatures. We present a comprehensive study of four different types of DR: free-streaming, self-interacting (coupled), decoupling, and recoupling DR, and vary initial conditions to include both adiabatic and isocurvature perturbations. In addition to these properties, we also vary neutrino energy density, DR energy density, and the SM neutrino masses to perform a general analysis and study degeneracies among neutrino and DR properties. We derive constraints using the cosmic microwave background, large-scale structure, and supernova datasets. We find no significant preference for physics beyond the ΛCDM model, but data exhibit interesting interplays between different physical quantities. When the neutrino energy density is allowed to vary, we find that the cosmological dataset prefers massless free-streaming DR over massive neutrinos, leading to a significant relaxation of the neutrino mass bound. For some cases, we find indications for a non-zero DR isocurvature at small scales, although below 2σ. Our analysis also highlights the degeneracy of various DR parameters with the Hubble constant H0, resulting in a mild relaxation of the H0 tension.
{"title":"Cosmological constraints on secluded dark radiation","authors":"Jae Hyeok Chang, Peizhi Du, Subhajit Ghosh and Soubhik Kumar","doi":"10.1088/1475-7516/2026/02/075","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/075","url":null,"abstract":"Dark radiation (DR) is ubiquitous in physics beyond the Standard Model (SM), and its interactions with the SM and dark matter (DM) lead to a variety of interesting effects on cosmological observables. However, even in scenarios where DR is `secluded', i.e., only gravitationally interacting with SM and DM, it can leave discernible signatures. We present a comprehensive study of four different types of DR: free-streaming, self-interacting (coupled), decoupling, and recoupling DR, and vary initial conditions to include both adiabatic and isocurvature perturbations. In addition to these properties, we also vary neutrino energy density, DR energy density, and the SM neutrino masses to perform a general analysis and study degeneracies among neutrino and DR properties. We derive constraints using the cosmic microwave background, large-scale structure, and supernova datasets. We find no significant preference for physics beyond the ΛCDM model, but data exhibit interesting interplays between different physical quantities. When the neutrino energy density is allowed to vary, we find that the cosmological dataset prefers massless free-streaming DR over massive neutrinos, leading to a significant relaxation of the neutrino mass bound. For some cases, we find indications for a non-zero DR isocurvature at small scales, although below 2σ. Our analysis also highlights the degeneracy of various DR parameters with the Hubble constant H0, resulting in a mild relaxation of the H0 tension.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"75 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146777169","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 : 2026-02-23DOI: 10.1088/1475-7516/2026/02/078
Simran Arora, Debasish Borah, Arnab Dasgupta, P.S. Bhupal Dev and Devabrat Mahanta
We propose a minimal extension of the type-I seesaw model to realise leptogenesis from the coannihilation of dark sector particles. The type-I seesaw model is extended with a singlet fermion and two singlet scalars charged under a Z2 symmetry. The Z2-odd singlet scalar is the dark matter candidate. Here the usual type-I seesaw mechanism generates neutrino mass, and a net lepton asymmetry is generated from the coannihilation of the dark matter and the Z2-odd singlet fermion. The Z2-even singlet scalar is important in dark matter phenomenology. Successful leptogenesis is possible at TeV-scale, unlike the vanilla case. This minimal extension provides an elegant explanation of successful leptogenesis with direct connection to the dark matter abundance in the Universe.
{"title":"Leptogenesis from dark matter coannihilation","authors":"Simran Arora, Debasish Borah, Arnab Dasgupta, P.S. Bhupal Dev and Devabrat Mahanta","doi":"10.1088/1475-7516/2026/02/078","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/078","url":null,"abstract":"We propose a minimal extension of the type-I seesaw model to realise leptogenesis from the coannihilation of dark sector particles. The type-I seesaw model is extended with a singlet fermion and two singlet scalars charged under a Z2 symmetry. The Z2-odd singlet scalar is the dark matter candidate. Here the usual type-I seesaw mechanism generates neutrino mass, and a net lepton asymmetry is generated from the coannihilation of the dark matter and the Z2-odd singlet fermion. The Z2-even singlet scalar is important in dark matter phenomenology. Successful leptogenesis is possible at TeV-scale, unlike the vanilla case. This minimal extension provides an elegant explanation of successful leptogenesis with direct connection to the dark matter abundance in the Universe.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"12 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146777171","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 : 2026-02-23DOI: 10.1088/1475-7516/2026/02/076
Sudipta Das and Mary Hall Reno
A new neutrino-matter interaction can potentially affect neutrino propagation through matter. In this work, we explore the impact of a flavor-conserving scalar-mediated non-standard neutrino interaction in the supernova neutrino flux. We observe that the presence of a scalar interaction involving muon and tau neutrinos (parameterized as ημμ and ηττ, respectively) can invert the neutrino mass eigenstate in which three neutrino flavor states are produced inside the supernova core, resulting in a significant modification of the electron neutrino flux from the supernova reaching the Earth. In the context of the DUNE experiment, we estimate the number of supernova neutrino events in the presence of scalar non-standard neutrino interaction ημμ or ηττ and contrast with the case without scalar-mediated non-standard interactions. Our results indicate that such scalar interactions introduce a new degeneracy in the measurement of neutrino mass ordering from supernova neutrinos. We show how the ν̅e event distribution in Hyper-Kamiokande experiment may help resolve the degeneracy between a model with new scalar interactions for normal ordered neutrino masses and the standard model with inverted mass ordering for a galactic supernova.
{"title":"Probing scalar non-standard interaction of supernova neutrinos in next-generation neutrino experiments","authors":"Sudipta Das and Mary Hall Reno","doi":"10.1088/1475-7516/2026/02/076","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/076","url":null,"abstract":"A new neutrino-matter interaction can potentially affect neutrino propagation through matter. In this work, we explore the impact of a flavor-conserving scalar-mediated non-standard neutrino interaction in the supernova neutrino flux. We observe that the presence of a scalar interaction involving muon and tau neutrinos (parameterized as ημμ and ηττ, respectively) can invert the neutrino mass eigenstate in which three neutrino flavor states are produced inside the supernova core, resulting in a significant modification of the electron neutrino flux from the supernova reaching the Earth. In the context of the DUNE experiment, we estimate the number of supernova neutrino events in the presence of scalar non-standard neutrino interaction ημμ or ηττ and contrast with the case without scalar-mediated non-standard interactions. Our results indicate that such scalar interactions introduce a new degeneracy in the measurement of neutrino mass ordering from supernova neutrinos. We show how the ν̅e event distribution in Hyper-Kamiokande experiment may help resolve the degeneracy between a model with new scalar interactions for normal ordered neutrino masses and the standard model with inverted mass ordering for a galactic supernova.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"67 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146778108","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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