Andrew Repp, István Szapudi

The counts-in-cells (CIC) galaxy probability distribution depends on both the dark matter clustering amplitude $\sigma_8$ and the galaxy bias $b$. We present a theory for the CIC distribution based on a previous prescription of the underlying dark matter distribution and a linear volume transformation to redshift space. We show that, unlike the power spectrum, the CIC distribution breaks the degeneracy between $\sigma_8$ and $b$ on scales large enough that both bias and redshift distortions are still linear; thus we obtain a simultaneous fit for both parameters. We first validate the technique on the Millennium Simulation and then apply it to the SDSS Main Galaxy Sample. We find $\sigma_8 = 0.94^{+.11}_{-.10}$ and $b = 1.36^{+.14}_{-.11}$, consistent with previous complementary results from redshift distortions and from Planck.

Clifford Cheung, James Mangan, Chia-Hsien Shen

We argue that conformal invariance is a common thread linking scalar effective field theories appearing in the double copy. For a derivatively coupled scalar with a quartic ${\cal O}(p^4)$ vertex, classical conformal invariance dictates an infinite tower of additional interactions that coincide exactly with Dirac-Born-Infeld theory analytically continued to spacetime dimension $D=0$. For the case of a quartic ${\cal O}(p^6)$ vertex, classical conformal invariance constrains the theory to be the special Galileon in $D=-2$ dimensions. We also verify the conformal invariance of these theories by showing that their amplitudes are uniquely fixed by the conformal Ward identities. In these theories conformal invariance is a much more stringent constraint than scale invariance.

Alexandre Arbey, Jérémy Auffinger, Joseph Silk

We evaluate abundance anomalies generated in patches of the universe where the baryon-to-photon ratio was locally enhanced by possibly many orders of magnitude in the range $\eta = 10^{-10} - 10^{-1}$. Our study is motivated by the possible survival of rare dense regions in the early universe, the most extreme of which, above a critical threshold, collapsed to form primordial black holes. If this occurred, one may expect there to also be a significant population of early-forming stars that formed in similar but subthreshold patches. We derive a range of element abundance signatures by performing BBN simulations at high values of the baryon-to-photon ratio that may be detectable in any surviving first generation stars of around a solar mass. Our predictions apply to metal-poor galactic halo stars, to old globular star clusters and to dwarf galaxies, and we compare with observations in each of these cases.

Rafael C. Nunes, Fabio Pacucci

Supermassive black holes (SMBHs) play a crucial role in the evolution of galaxies and are currently detected up to $z\sim 7.5$. Theories describing black hole (BH) growth are challenged by how rapidly seeds with initial mass $M_{\bullet} \lesssim 10^5 \, \mathrm{M_{\odot}}$, formed at $z \sim 20-30$, grew to $M_{\bullet} \sim 10^9 \, \mathrm{M_{\odot}}$ by $z\sim 7$. Here we study the effects of the value of the Hubble parameter, $H_0$, on models describing the early growth of BHs. First, we note that the predicted mass of a quasar at $z=6$ changes by $> 300$% if the underlying Hubble parameter used in the model varies from $H_0 = 65$ to $H_0 = 74$ km s$^{-1}$Mpc$^{-1}$, a range encompassing current estimates. Employing an MCMC approach based on priors from $z \gtrsim 6.5$ quasars and on $H_0$, we study the interconnection between $H_0$ and the parameters describing BH growth: seed mass $M_i$ and Eddington ratio $f_{\rm Edd}$. Assuming an Eddington ratio of $f_{\rm Edd} = 0.7$, in agreement with previous estimates, we find $H_0 = 73.6^{+1.2}_{-3.3}$ km s$^{-1}$Mpc$^{-1}$. In a second analysis, allowing all the parameters to vary freely, we find $\log(M_{i}/\mathrm{M_{\odot}}) > 4.5$ (at 95% CL), $H_0 = 74^{+1.5}_{-1.4}$ km s$^{-1}$Mpc$^{-1}$ and $f_{\rm Edd}=0.77^{+0.035}_{-0.026}$ at 68% CL. Our results on the typical Eddington ratio are in agreement with previous estimates. Current values of the Hubble parameter strongly favour heavy seed formation scenarios, with $M_i \gtrsim 10^4 \, \mathrm{M_{\odot}}$. In our model, with the priors on BH masses of quasars used, light seed formation scenarios are rejected at $\sim 3\sigma$.

Adam Falkowski, Camila S. Machado

We discuss recursion relations for scattering amplitudes with massive particles of any spin. They are derived via a two-parameter shift of momenta, combining a BCFW-type spinor shift with the soft limit of a massless particle involved in the process. The technical innovation is that spinors corresponding to massive momenta are also shifted. Our recursions lead to a reformulation of the soft theorems. The well-known Weinberg's soft factors are recovered and, in addition, the subleading factors appear reshaped such that they are directly applicable to massive amplitudes in the modern on-shell language. Moreover, we obtain new results in the context of non-minimal interactions of massive matter with photons and gravitons. These soft theorems are employed for practical calculations of Compton and higher-point scattering. As a by-product, we introduce a convenient representation of the Compton scattering amplitude for any mass and spin.

Jagjit Singh Sidhu, Robert J. Scherrer, Glenn Starkman

Antimatter macroscopic dark matter {\bob (macros)} refers to a generic {\bob class} of antimatter dark matter candidates that interact with ordinary matter primarily through annihilation with large cross-sections. A combination of terrestrial, astrophysical, and cosmological observations constrain a portion of the anti-macro parameter space. However, a large region of the parameter space remains unconstrained, most notably for nuclear-dense objects.

Zvi Bern, Julio Parra-Martinez, Eric Sawyer

We describe on-shell methods for computing one- and two-loop anomalous dimensions in the context of effective field theories containing higher-dimension operators. We also summarize methods for computing one-loop amplitudes, which are used as inputs to the computation of two-loop anomalous dimensions, and we explain how the structure of rational terms and judicious renormalization scheme choices can lead to additional vanishing terms in the anomalous dimension matrix at two loops. We describe the two-loop implications for the Standard Model Effective Field Theory (SMEFT). As a by-product of this analysis we verify a variety of one-loop SMEFT anomalous dimensions computed by Alonso, Jenkins, Manohar and Trott.