Daniel Green

"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.

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

There are other tensions in their data that may or may not be related but were not really investigated. E.g. the measurement of the phase shift (Neff), shows a 2.7 sigma tension with the SM (arxiv.org/abs/2412.05990). Could trade all of the DE signals for just a phase shift?

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

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

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.

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.

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

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)

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

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.

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

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

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.

These papers should be read with Polchinski's review of the CC problem arxiv.org/abs/hep-th/0... He nicely explains why this type of solution usually doesn't work: vacuum loops contribute to the mass/energy of many states and must couple to gravity universally.

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.

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.

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.

They show that everything allowed by symmetries should be included & short distance physics is absorbed by the parameters. They also show tidal tensor bias is generated by RG (and is therefore required). A lot of related ideas become better know via the EFT of LSS arxiv.org/abs/1004.2488

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

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...).