Daniel Green
@dangreen.bsky.social
Associate Professor @UCSanDiego, particle theory and cosmology
Reminder: Effective field theory is a revolutionary development in fundamental physics that has transformed the field over the past 40 years (that also makes many verified experimental predictions).
Congrats to @jfdonoghue.bsky.social !
Congrats to @jfdonoghue.bsky.social !
November 5, 2025 at 7:49 PM
Reminder: Effective field theory is a revolutionary development in fundamental physics that has transformed the field over the past 40 years (that also makes many verified experimental predictions).
Congrats to @jfdonoghue.bsky.social !
Congrats to @jfdonoghue.bsky.social !
For (cosmic) neutrino mass enthusiasts: Peter Graham, Joel Meyers and I have new paper, breaking down why data prefers "negative" masses and how it might be explained with new fields and/or forces. We point to a number of measurements that would clarify the situation
arxiv.org/abs/2508.20999
arxiv.org/abs/2508.20999
August 29, 2025 at 2:59 AM
For (cosmic) neutrino mass enthusiasts: Peter Graham, Joel Meyers and I have new paper, breaking down why data prefers "negative" masses and how it might be explained with new fields and/or forces. We point to a number of measurements that would clarify the situation
arxiv.org/abs/2508.20999
arxiv.org/abs/2508.20999
"Putative dark matter particles with masses below around 1 MeV are not ruled out by astronomical observations"
Fact check: astrophysics provides a constraint that is 20 orders of magnitude stronger than this new result.
Fact check: astrophysics provides a constraint that is 20 orders of magnitude stronger than this new result.
August 22, 2025 at 4:29 PM
"Putative dark matter particles with masses below around 1 MeV are not ruled out by astronomical observations"
Fact check: astrophysics provides a constraint that is 20 orders of magnitude stronger than this new result.
Fact check: astrophysics provides a constraint that is 20 orders of magnitude stronger than this new result.
The paper is out here: pole.uchicago.edu/public/data/...
Of personal interest: the full range of neutrino masses allowed by neutrino oscillations are now excluded at 98% confidence!
Of personal interest: the full range of neutrino masses allowed by neutrino oscillations are now excluded at 98% confidence!
June 25, 2025 at 6:22 PM
The paper is out here: pole.uchicago.edu/public/data/...
Of personal interest: the full range of neutrino masses allowed by neutrino oscillations are now excluded at 98% confidence!
Of personal interest: the full range of neutrino masses allowed by neutrino oscillations are now excluded at 98% confidence!
Reposted by Daniel Green
Let the science begin! 🥁
On May 1, NASA’s SPHEREx space observatory began regular science operations, which consist of taking about 3,600 images per day.
Read more here: spherex.caltech.edu/news/nasa-s-...
On May 1, NASA’s SPHEREx space observatory began regular science operations, which consist of taking about 3,600 images per day.
Read more here: spherex.caltech.edu/news/nasa-s-...
May 8, 2025 at 12:18 AM
Let the science begin! 🥁
On May 1, NASA’s SPHEREx space observatory began regular science operations, which consist of taking about 3,600 images per day.
Read more here: spherex.caltech.edu/news/nasa-s-...
On May 1, NASA’s SPHEREx space observatory began regular science operations, which consist of taking about 3,600 images per day.
Read more here: spherex.caltech.edu/news/nasa-s-...
Reposted by Daniel Green
Is dark energy weakening? DESI’s results are ambiguous
You've heard the results last week: the DESI collaboration announced evidence for evolving dark energy.
But that's not the only interpretation when the full suite of data just doesn't add up.
bigthink.com/starts-with-...
#space #physics
You've heard the results last week: the DESI collaboration announced evidence for evolving dark energy.
But that's not the only interpretation when the full suite of data just doesn't add up.
bigthink.com/starts-with-...
#space #physics
Is dark energy weakening? DESI's results are ambiguous
DESI, by mapping galaxies, has claimed they see evidence for dark energy evolving by getting weaker. But that's only one interpretation.
bigthink.com
March 26, 2025 at 4:21 PM
Is dark energy weakening? DESI’s results are ambiguous
You've heard the results last week: the DESI collaboration announced evidence for evolving dark energy.
But that's not the only interpretation when the full suite of data just doesn't add up.
bigthink.com/starts-with-...
#space #physics
You've heard the results last week: the DESI collaboration announced evidence for evolving dark energy.
But that's not the only interpretation when the full suite of data just doesn't add up.
bigthink.com/starts-with-...
#space #physics
PSA: when a collaboration whose name starts with DE says they have found evidence for non-standard dark energy, the community should take that interpretation with more skepticism.
DESI does not show that w0wa explains there data. Eg neutrino mass remains negative even with w0wa
DESI does not show that w0wa explains there data. Eg neutrino mass remains negative even with w0wa
March 22, 2025 at 6:35 PM
PSA: when a collaboration whose name starts with DE says they have found evidence for non-standard dark energy, the community should take that interpretation with more skepticism.
DESI does not show that w0wa explains there data. Eg neutrino mass remains negative even with w0wa
DESI does not show that w0wa explains there data. Eg neutrino mass remains negative even with w0wa
Dec 31 - Lower bound on primordial non-Gaussianity
arxiv.org/abs/1612.00033
Cabass et al. show that inflation predicts a lower bound of equilateral NG of 0.1 x (n_s-1), 3-4 orders of magnitude below the current limits, due to gravity. The search for NG has a set range and target
arxiv.org/abs/1612.00033
Cabass et al. show that inflation predicts a lower bound of equilateral NG of 0.1 x (n_s-1), 3-4 orders of magnitude below the current limits, due to gravity. The search for NG has a set range and target
December 31, 2024 at 8:37 AM
Dec 31 - Lower bound on primordial non-Gaussianity
arxiv.org/abs/1612.00033
Cabass et al. show that inflation predicts a lower bound of equilateral NG of 0.1 x (n_s-1), 3-4 orders of magnitude below the current limits, due to gravity. The search for NG has a set range and target
arxiv.org/abs/1612.00033
Cabass et al. show that inflation predicts a lower bound of equilateral NG of 0.1 x (n_s-1), 3-4 orders of magnitude below the current limits, due to gravity. The search for NG has a set range and target
Dec 30 - CMB Bispectrum modal decomposition
arxiv.org/abs/0912.5516
Fergusson et al. define a basis of orthogonal polynomials on the space of CMB 3pt functions, vastly reducing the need to find models on which to build non-Gaussian templates. Planck bounds the first 2000 terms.
arxiv.org/abs/0912.5516
Fergusson et al. define a basis of orthogonal polynomials on the space of CMB 3pt functions, vastly reducing the need to find models on which to build non-Gaussian templates. Planck bounds the first 2000 terms.
December 30, 2024 at 8:39 AM
Dec 30 - CMB Bispectrum modal decomposition
arxiv.org/abs/0912.5516
Fergusson et al. define a basis of orthogonal polynomials on the space of CMB 3pt functions, vastly reducing the need to find models on which to build non-Gaussian templates. Planck bounds the first 2000 terms.
arxiv.org/abs/0912.5516
Fergusson et al. define a basis of orthogonal polynomials on the space of CMB 3pt functions, vastly reducing the need to find models on which to build non-Gaussian templates. Planck bounds the first 2000 terms.
Dec 29 - Dispersion Relations & EFT
arxiv.org/abs/hep-ph/9...
Donoghue shows how to use subtracted dispersion relations to expose the structure of EFT. Specifically, this technique precisely illustrates UV information can be traded to local contact interactions.
arxiv.org/abs/hep-ph/9...
Donoghue shows how to use subtracted dispersion relations to expose the structure of EFT. Specifically, this technique precisely illustrates UV information can be traded to local contact interactions.
December 29, 2024 at 9:02 AM
Dec 29 - Dispersion Relations & EFT
arxiv.org/abs/hep-ph/9...
Donoghue shows how to use subtracted dispersion relations to expose the structure of EFT. Specifically, this technique precisely illustrates UV information can be traded to local contact interactions.
arxiv.org/abs/hep-ph/9...
Donoghue shows how to use subtracted dispersion relations to expose the structure of EFT. Specifically, this technique precisely illustrates UV information can be traded to local contact interactions.
Dec 28 - Scattering and CFT Unitarity Bounds
arxiv.org/abs/0801.1140
While officially addressing the topic of "unparticles", Grinstein et al. rederive bounds on the dimensions of operators from the unitarity of scattering a weakly coupled spectator off a strongly coupled CFT
arxiv.org/abs/0801.1140
While officially addressing the topic of "unparticles", Grinstein et al. rederive bounds on the dimensions of operators from the unitarity of scattering a weakly coupled spectator off a strongly coupled CFT
December 28, 2024 at 8:51 AM
Dec 28 - Scattering and CFT Unitarity Bounds
arxiv.org/abs/0801.1140
While officially addressing the topic of "unparticles", Grinstein et al. rederive bounds on the dimensions of operators from the unitarity of scattering a weakly coupled spectator off a strongly coupled CFT
arxiv.org/abs/0801.1140
While officially addressing the topic of "unparticles", Grinstein et al. rederive bounds on the dimensions of operators from the unitarity of scattering a weakly coupled spectator off a strongly coupled CFT
Dec 27 - Weinberg Soft Theorems from Weinberg Adiabatic Modes
arxiv.org/abs/1602.05196
Mirbabayi & Simonovic show that the photon and graviton soft theorems for scattering in flat space are a consequence of physical long wavelength configurations tied to large diffs (BSM)
arxiv.org/abs/1602.05196
Mirbabayi & Simonovic show that the photon and graviton soft theorems for scattering in flat space are a consequence of physical long wavelength configurations tied to large diffs (BSM)
December 27, 2024 at 7:37 AM
Dec 27 - Weinberg Soft Theorems from Weinberg Adiabatic Modes
arxiv.org/abs/1602.05196
Mirbabayi & Simonovic show that the photon and graviton soft theorems for scattering in flat space are a consequence of physical long wavelength configurations tied to large diffs (BSM)
arxiv.org/abs/1602.05196
Mirbabayi & Simonovic show that the photon and graviton soft theorems for scattering in flat space are a consequence of physical long wavelength configurations tied to large diffs (BSM)
Dec 26 - Conformal Invariance of Cosmological Correlators
arxiv.org/abs/1108.0874
Creminelli shows that the structure of cosmic observables follows from conformal Ward identities. He gives simple examples at 3- and 4-points that are a starting point for more complex problems
arxiv.org/abs/1108.0874
Creminelli shows that the structure of cosmic observables follows from conformal Ward identities. He gives simple examples at 3- and 4-points that are a starting point for more complex problems
December 26, 2024 at 6:29 AM
Dec 26 - Conformal Invariance of Cosmological Correlators
arxiv.org/abs/1108.0874
Creminelli shows that the structure of cosmic observables follows from conformal Ward identities. He gives simple examples at 3- and 4-points that are a starting point for more complex problems
arxiv.org/abs/1108.0874
Creminelli shows that the structure of cosmic observables follows from conformal Ward identities. He gives simple examples at 3- and 4-points that are a starting point for more complex problems
Dec 25 - CMB Peak Locations
arxiv.org/abs/1603.03091
Pan et al. use (semi-)analytic methods to model the location of all the CMB peaks at the level of the Planck peak measurements in TTTEEE (<1%). Many corrections are 1-10% and thus are essential for consistency with data.
arxiv.org/abs/1603.03091
Pan et al. use (semi-)analytic methods to model the location of all the CMB peaks at the level of the Planck peak measurements in TTTEEE (<1%). Many corrections are 1-10% and thus are essential for consistency with data.
December 25, 2024 at 4:50 AM
Dec 25 - CMB Peak Locations
arxiv.org/abs/1603.03091
Pan et al. use (semi-)analytic methods to model the location of all the CMB peaks at the level of the Planck peak measurements in TTTEEE (<1%). Many corrections are 1-10% and thus are essential for consistency with data.
arxiv.org/abs/1603.03091
Pan et al. use (semi-)analytic methods to model the location of all the CMB peaks at the level of the Planck peak measurements in TTTEEE (<1%). Many corrections are 1-10% and thus are essential for consistency with data.
Dec 24 - Cosmic Bell Inequalities
arxiv.org/abs/1508.01082
Maldacena writes down a model of inflation where the statistics of certain hot and cold spots encode the outcome of a Bell-measurement. This shows that the quantum nature of inflation can survive in conventional classical observables
arxiv.org/abs/1508.01082
Maldacena writes down a model of inflation where the statistics of certain hot and cold spots encode the outcome of a Bell-measurement. This shows that the quantum nature of inflation can survive in conventional classical observables
December 24, 2024 at 6:19 AM
Dec 24 - Cosmic Bell Inequalities
arxiv.org/abs/1508.01082
Maldacena writes down a model of inflation where the statistics of certain hot and cold spots encode the outcome of a Bell-measurement. This shows that the quantum nature of inflation can survive in conventional classical observables
arxiv.org/abs/1508.01082
Maldacena writes down a model of inflation where the statistics of certain hot and cold spots encode the outcome of a Bell-measurement. This shows that the quantum nature of inflation can survive in conventional classical observables
Dec 23 - Analytic CMB Polarization
arxiv.org/abs/astro-ph...
Zaldarriaga & Harari give a thorough analytic treatment of how polarized scattering affects the evolution of the photon distribution function and the appearance of temperature and polarized CMB anisotropies
arxiv.org/abs/astro-ph...
Zaldarriaga & Harari give a thorough analytic treatment of how polarized scattering affects the evolution of the photon distribution function and the appearance of temperature and polarized CMB anisotropies
December 23, 2024 at 5:43 AM
Dec 23 - Analytic CMB Polarization
arxiv.org/abs/astro-ph...
Zaldarriaga & Harari give a thorough analytic treatment of how polarized scattering affects the evolution of the photon distribution function and the appearance of temperature and polarized CMB anisotropies
arxiv.org/abs/astro-ph...
Zaldarriaga & Harari give a thorough analytic treatment of how polarized scattering affects the evolution of the photon distribution function and the appearance of temperature and polarized CMB anisotropies
Dec 22 - Fat Gravitons and the CC
arxiv.org/abs/hep-th/0...
arxiv.org/abs/hep-th/0...
Sundrum tries to construct a theory of gravity where vacuum loops don't gravitate. This theory is non-local in a non-trivial way in order to avoid the very strong equivalence principle constraints in this idea.
arxiv.org/abs/hep-th/0...
arxiv.org/abs/hep-th/0...
Sundrum tries to construct a theory of gravity where vacuum loops don't gravitate. This theory is non-local in a non-trivial way in order to avoid the very strong equivalence principle constraints in this idea.
December 22, 2024 at 6:08 AM
Dec 22 - Fat Gravitons and the CC
arxiv.org/abs/hep-th/0...
arxiv.org/abs/hep-th/0...
Sundrum tries to construct a theory of gravity where vacuum loops don't gravitate. This theory is non-local in a non-trivial way in order to avoid the very strong equivalence principle constraints in this idea.
arxiv.org/abs/hep-th/0...
arxiv.org/abs/hep-th/0...
Sundrum tries to construct a theory of gravity where vacuum loops don't gravitate. This theory is non-local in a non-trivial way in order to avoid the very strong equivalence principle constraints in this idea.
Dec 21 - Conformal Technicolor
arxiv.org/abs/hep-ph/0...
Luty & Okui rephrase the hierarchy problem as a statement about the relationship between the dimensions of operators. The idea is that the Higgs has a dimension near 1 but all the operators in its OPE have dimensions > 4.
arxiv.org/abs/hep-ph/0...
Luty & Okui rephrase the hierarchy problem as a statement about the relationship between the dimensions of operators. The idea is that the Higgs has a dimension near 1 but all the operators in its OPE have dimensions > 4.
December 21, 2024 at 8:10 AM
Dec 21 - Conformal Technicolor
arxiv.org/abs/hep-ph/0...
Luty & Okui rephrase the hierarchy problem as a statement about the relationship between the dimensions of operators. The idea is that the Higgs has a dimension near 1 but all the operators in its OPE have dimensions > 4.
arxiv.org/abs/hep-ph/0...
Luty & Okui rephrase the hierarchy problem as a statement about the relationship between the dimensions of operators. The idea is that the Higgs has a dimension near 1 but all the operators in its OPE have dimensions > 4.
Dec 20 - Spontaneously broken spacetime symmetries
arxiv.org/abs/hep-th/0...
Low & Manohar explain why there are often fewer Goldstone modes than broken generators for spacetime symmetries. A goldstone acts like a local symmetry, which is not unique to a single global generator.
arxiv.org/abs/hep-th/0...
Low & Manohar explain why there are often fewer Goldstone modes than broken generators for spacetime symmetries. A goldstone acts like a local symmetry, which is not unique to a single global generator.
December 20, 2024 at 8:26 AM
Dec 20 - Spontaneously broken spacetime symmetries
arxiv.org/abs/hep-th/0...
Low & Manohar explain why there are often fewer Goldstone modes than broken generators for spacetime symmetries. A goldstone acts like a local symmetry, which is not unique to a single global generator.
arxiv.org/abs/hep-th/0...
Low & Manohar explain why there are often fewer Goldstone modes than broken generators for spacetime symmetries. A goldstone acts like a local symmetry, which is not unique to a single global generator.
Dec 19 - Renormalizing Bias Parameters
arxiv.org/abs/astro-ph...
arxiv.org/pdf/0902.0991
McDonald (+ Roy) show how describing the statistics of tracers of dark matter (such as galaxies) requires renormalization of the bias parameters. They anticipate/discover the EFT structure found later.
arxiv.org/abs/astro-ph...
arxiv.org/pdf/0902.0991
McDonald (+ Roy) show how describing the statistics of tracers of dark matter (such as galaxies) requires renormalization of the bias parameters. They anticipate/discover the EFT structure found later.
December 19, 2024 at 8:58 AM
Dec 19 - Renormalizing Bias Parameters
arxiv.org/abs/astro-ph...
arxiv.org/pdf/0902.0991
McDonald (+ Roy) show how describing the statistics of tracers of dark matter (such as galaxies) requires renormalization of the bias parameters. They anticipate/discover the EFT structure found later.
arxiv.org/abs/astro-ph...
arxiv.org/pdf/0902.0991
McDonald (+ Roy) show how describing the statistics of tracers of dark matter (such as galaxies) requires renormalization of the bias parameters. They anticipate/discover the EFT structure found later.
Dec 18 - Indirect Evidence for Quantum Gravity
journals.aps.org/prl/abstract...
Page and Geilker design and perform an experiment to test if gravity is only (semi-) classical. They test and exclude the hypothesis that gravity is classical but couples to the quantum averaged stress tensor of matter
journals.aps.org/prl/abstract...
Page and Geilker design and perform an experiment to test if gravity is only (semi-) classical. They test and exclude the hypothesis that gravity is classical but couples to the quantum averaged stress tensor of matter
December 18, 2024 at 9:11 AM
Dec 18 - Indirect Evidence for Quantum Gravity
journals.aps.org/prl/abstract...
Page and Geilker design and perform an experiment to test if gravity is only (semi-) classical. They test and exclude the hypothesis that gravity is classical but couples to the quantum averaged stress tensor of matter
journals.aps.org/prl/abstract...
Page and Geilker design and perform an experiment to test if gravity is only (semi-) classical. They test and exclude the hypothesis that gravity is classical but couples to the quantum averaged stress tensor of matter
Dec 17 - Positivity Bounds
journals.aps.org/prd/abstract...
In 1985, Pham and Truong use dispersion relations to show that the 4 derivative term in pi-pi scattering must be positive. This was rediscovered (and generalized) 20 years later by Adams et al (arxiv.org/abs/hep-th/0...).
journals.aps.org/prd/abstract...
In 1985, Pham and Truong use dispersion relations to show that the 4 derivative term in pi-pi scattering must be positive. This was rediscovered (and generalized) 20 years later by Adams et al (arxiv.org/abs/hep-th/0...).
December 17, 2024 at 9:02 AM
Dec 17 - Positivity Bounds
journals.aps.org/prd/abstract...
In 1985, Pham and Truong use dispersion relations to show that the 4 derivative term in pi-pi scattering must be positive. This was rediscovered (and generalized) 20 years later by Adams et al (arxiv.org/abs/hep-th/0...).
journals.aps.org/prd/abstract...
In 1985, Pham and Truong use dispersion relations to show that the 4 derivative term in pi-pi scattering must be positive. This was rediscovered (and generalized) 20 years later by Adams et al (arxiv.org/abs/hep-th/0...).
Dec 16 - CMB Trispectrum constraints
arxiv.org/abs/2205.14408
arxiv.org/abs/1502.00635
These papers place the best constraints on primordial 4-point functions using Planck CMB data. Planck explored 3-point functions is great detail but analyses at higher points have been limited.
arxiv.org/abs/2205.14408
arxiv.org/abs/1502.00635
These papers place the best constraints on primordial 4-point functions using Planck CMB data. Planck explored 3-point functions is great detail but analyses at higher points have been limited.
December 16, 2024 at 8:16 AM
Dec 16 - CMB Trispectrum constraints
arxiv.org/abs/2205.14408
arxiv.org/abs/1502.00635
These papers place the best constraints on primordial 4-point functions using Planck CMB data. Planck explored 3-point functions is great detail but analyses at higher points have been limited.
arxiv.org/abs/2205.14408
arxiv.org/abs/1502.00635
These papers place the best constraints on primordial 4-point functions using Planck CMB data. Planck explored 3-point functions is great detail but analyses at higher points have been limited.
Dec 15 - Scattering amplitudes and Navier-Stokes
arxiv.org/abs/2010.15970
www.sciencedirect.com/science/arti...
Cheung & Mangan (building on an old paper by Wyld) study fluid dynamics through the lens of scattering amplitudes. They find new structures in fluids, particularly the double-copy
arxiv.org/abs/2010.15970
www.sciencedirect.com/science/arti...
Cheung & Mangan (building on an old paper by Wyld) study fluid dynamics through the lens of scattering amplitudes. They find new structures in fluids, particularly the double-copy
December 15, 2024 at 8:13 AM
Dec 15 - Scattering amplitudes and Navier-Stokes
arxiv.org/abs/2010.15970
www.sciencedirect.com/science/arti...
Cheung & Mangan (building on an old paper by Wyld) study fluid dynamics through the lens of scattering amplitudes. They find new structures in fluids, particularly the double-copy
arxiv.org/abs/2010.15970
www.sciencedirect.com/science/arti...
Cheung & Mangan (building on an old paper by Wyld) study fluid dynamics through the lens of scattering amplitudes. They find new structures in fluids, particularly the double-copy
Dec 14 - cosmological perturbation theory in 1+1 D
arxiv.org/abs/1502.07389
McQuinn and White study the evolution of structure in 1+1 dimensions, where the all-loop results can be calculated. They show SPT has a finite radius of convergence but doesn't converge to simulations.
arxiv.org/abs/1502.07389
McQuinn and White study the evolution of structure in 1+1 dimensions, where the all-loop results can be calculated. They show SPT has a finite radius of convergence but doesn't converge to simulations.
December 14, 2024 at 10:02 AM
Dec 14 - cosmological perturbation theory in 1+1 D
arxiv.org/abs/1502.07389
McQuinn and White study the evolution of structure in 1+1 dimensions, where the all-loop results can be calculated. They show SPT has a finite radius of convergence but doesn't converge to simulations.
arxiv.org/abs/1502.07389
McQuinn and White study the evolution of structure in 1+1 dimensions, where the all-loop results can be calculated. They show SPT has a finite radius of convergence but doesn't converge to simulations.