Search

We present the quasar luminosity function (LF) at $z = 7$, measured with 35 spectroscopically confirmed quasars at $6.55 < z < 7.15$. The sample of 22 quasars from the Subaru High-$z$ Exploration of Low-Luminosity Quasars (SHELLQs) project, combined with 13 brighter quasars in the literature, covers an unprecedentedly wide range of rest-frame ultraviolet magnitudes over $-28 < M_{1450} < -23$. We found that the binned LF flattens significantly toward the faint end populated by the SHELLQs quasars. A maximum likelihood fit to a double power-law model has a break magnitude $M^*_{1450} = -25.60^{+0.40}_{-0.30}$, a characteristic density $\Phi^* = 1.35^{+0.47}_{-0.30}$ Gpc$^{-3}$ mag$^{-1}$, and a bright-end slope $\beta = -3.34^{+0.49}_{-0.57}$, when the faint-end slope is fixed to $\alpha = -1.2$ as observed at $z \le 6$. The overall LF shape remains remarkably similar from $z = 4$ to $7$, while the amplitude decreases substantially toward higher redshifts, with a clear indication of an accelerating decline at $z \ge 6$. The estimated ionizing photon density, $10^{48.2 \pm 0.1}$ s$^{-1}$ Mpc$^{-3}$, is less than 1 % of the critical rate to keep the intergalactic medium ionized at $z = 7$, and thus indicates that quasars are not a major contributor to cosmic reionization., Comment: The Astrophysical Journal Letters, in press

We present cosmology results from a blinded joint analysis of cosmic shear, $\xi_{\pm}(\vartheta)$, galaxy-galaxy weak lensing, $\Delta\!\Sigma(R)$, and projected galaxy clustering, $w_{\rm p}(R)$, measured from the Hyper Suprime-Cam three-year (HSC-Y3) shape catalog and the Sloan Digital Sky Survey (SDSS) DR11 spectroscopic galaxy catalog - a 3$\times$2pt cosmology analysis. We define luminosity-cut samples of SDSS galaxies to serve as the tracers of $w_{\rm p}$ and as the lens samples for $\Delta\!\Sigma$ in three spectroscopic redshift bins spanning the range $0.15, Comment: 39 pages, 25 figures, 5 tables, for coordinated submission to PRD with other HSC Y3 weak lensing cosmology papers - see https://hsc-release.mtk.nao.ac.jp/doc/index.php/wly3/. arXiv admin note: text overlap with arXiv:2111.02419

We present a careful study of the chiral symmetry breaking minima and the baryonic directions in supersymmetric QCD ($SU(N_c)$ with $N_f$ flavors) perturbed by Anomaly Mediated Supersymmetry Breaking (AMSB). For the s-confining case of $N_f = N_c + 1$ and most of the free-magnetic phase ($N_f \leq 1.43 N_c$) we find that naive tree level baryonic runaways are stabilized by loop effects. Runaways are present, however, for the upper end of the free magnetic phase ($N_f \gtrsim 1.43 N_c$) and into conformal window, signaling the existence of incalculable minima at large field values of ${\cal O} (\Lambda)$. Nevertheless, the chiral symmetry breaking points are locally stable, and are expected to continuously connect to the vacua of QCD for large SUSY breaking. The case of $N_f = N_c$ requires particular care due to the inherently strongly coupled nature of the quantum modified moduli space. Due to the incalculability of critical K\"ahler potential terms, the stability of the chiral symmetry breaking point along baryonic directions cannot be determined for $N_f=N_c$. With the exception of this case, all theories to which AMSB can be applied ($N_f < 3 N_c$) possess stable chiral symmetry breaking minima, and all theories with $N_f \lesssim 1.43 N_c$ (aside from $N_f = N_f$) are protected from runaways to incalculable minima., Comment: 10 pages

We summarize the state of Beyond the Standard Model (BSM) model building in particle physics for Snowmass 2021, focusing mainly on several whitepaper contributions to BSM model building (TF08) and closely related areas., 44 pages, 1 figure, Submitted to the Proceedings of the US Community Study on the Future of Particle Physics (Snowmass 2021). Topical Group Report for TF08 - BSM Model Building

In this contribution to the Snowmass 2021 process we review theoretical developments in the Standard Model Effective Field Theory (SMEFT) with a focus on effects at the dimension-8 level and beyond. We review the theoretical advances that led to the complete construction of the operator bases for the dimension-8 and dimension-9 SMEFT Lagrangians. We discuss the possibility of obtaining all-orders results in the $1/\Lambda$ expansion for certain SMEFT observables as well as the current status of renormalization group running and implications for positivity, and briefly present the on-shell approach to constructing SMEFT amplitudes. Finally we present several new phenomenological effects that first arise at dimension-8 and discuss the impact of these terms on experimental analyses., Comment: 37 pages, 6 figures; contribution to Snowmass 2021; new section and additional authors

We demonstrate that SO(Nc) gauge theories with matter fields in the vector representation confine due to monopole condensation and break the SU(NF) chiral symmetry to SO(NF) via the quark bilinear. Our results are obtained by perturbing the N=1 supersymmetric theory with anomaly-mediated supersymmetry breaking.

We investigate the IR phases of nonsupersymmetric (non-SUSY) SO(Nc) gauge theories with NF fermions in the vector representation obtained by perturbing the SUSY theory with anomaly mediated SUSY breaking (AMSB). We find that of the wide variety of phases appearing in the SUSY theory only two survive: for NF≤32(Nc−2) the theory confines, breaking the SU(NF) global symmetry to SO(NF), while for 32(Nc−2)

We propose a new thermal dark matter candidate whose abundance is determined by the freezeout of inverse decays. The relic abundance depends parametrically only on a decay width, while matching the observed value requires that the coupling determining the width-and the width itself-should be exponentially small. The dark matter is therefore very weakly coupled to the Standard Model, evading conventional searches. This INverse DecaY ('INDY') dark matter can be discovered by searching for the long-lived particle that decays into the dark matter at future planned experiments., 7 pages, 3 figures

The symmetry breaking of grand unified gauge groups in the early Universe often leaves behind relic topological defects such as cosmic strings, domain walls, or monopoles. For some symmetry breaking chains, hybrid defects can form where cosmic strings attach to domain walls or monopoles attach to strings. In general, such hybrid defects are unstable, with one defect "eating" the other via the conversion of its rest mass into the other's kinetic energy and subsequently decaying via gravitational waves. In this work, we determine the gravitational wave spectrum from 1) the destruction of a cosmic string network by the nucleation of monopoles which cut up and "eat" the strings, 2) the collapse and decay of a monopole-string network by strings that "eat" the monopoles, 3) the destruction of a domain wall network by the nucleation of string-bounded holes on the wall that expand and "eat" the wall, and 4) the collapse and decay of a string-bounded wall network by walls that "eat" the strings. We call the gravitational wave signals produced from the "eating" of one topological defect by another gravitational wave gastronomy. We find that the four gravitational wave gastronomy signals considered yield unique spectra that can be used to narrow down the SO(10) symmetry breaking chain to the Standard Model and the scales of symmetry breaking associated with the consumed topological defects. Moreover, the systems we consider are unlikely to have a residual monopole or domain wall problem., 34 pages, 17 figures

During the preparatory phase of the International Linear Collider (ILC) project, all technical development and engineering design needed for the start of ILC construction must be completed, in parallel with intergovernmental discussion of governance and sharing of responsibilities and cost. The ILC Preparatory Laboratory (Pre-lab) is conceived to execute the technical and engineering work and to assist the intergovernmental discussion by providing relevant information upon request. It will be based on a worldwide partnership among laboratories with a headquarters hosted in Japan. This proposal, prepared by the ILC International Development Team and endorsed by the International Committee for Future Accelerators, describes an organisational framework and work plan for the Pre-lab. Elaboration, modification and adjustment should be introduced for its implementation, in order to incorporate requirements arising from the physics community, laboratories, and governmental authorities interested in the ILC., 48 pages, 5 figures

We propose a simple non-perturbative formalism for false vacuum decay using functional methods. We introduce the quasi-stationary effective action, a bounce action that non-perturbatively incorporates radiative corrections and is robust to strong couplings. The quasi-stationary effective action obeys an exact flow equation in a modified functional renormalization group with a motivated regulator functional. We demonstrate the use of this formalism in a simple toy model and compare our result with that obtained in perturbation theory., 26 pages, 2 figures; v2: added discussion, appendices, and references, corrected typos, switched to JHEP format

Existing searches for cosmic axions relics have relied heavily on the axion being non-relativistic and making up dark matter. However, light axions can be copiously produced in the early Universe and remain relativistic today, thereby constituting a Cosmic $\textit{axion}$ Background (C$a$B). As prototypical examples of axion sources, we consider thermal production, dark-matter decay, parametric resonance, and topological defect decay. Each of these has a characteristic frequency spectrum that can be searched for in axion direct detection experiments. We focus on the axion-photon coupling and study the sensitivity of current and future versions of ADMX, HAYSTAC, DMRadio, and ABRACADABRA to a C$a$B, finding that the data collected in search of dark matter can be repurposed to detect axion energy densities well below limits set by measurements of the energy budget of the Universe. In this way, direct detection of relativistic relics offers a powerful new opportunity to learn about the early Universe and, potentially, discover the axion., 31 pages, 11 figures, v3: corrected the source term for resonant cavity instruments, conclusions unchanged

To aid contributions to the Snowmass 2021 US Community Study on physics at the International Linear Collider and other proposed $e^+e^-$ colliders, we present a list of study questions that could be the basis of useful Snowmass projects. We accompany this with links to references and resources on $e^+e^-$ physics, and a description of a new software framework that we are preparing for $e^+e^-$ studies at Snowmass., Comment: 49 pages, 1 figure, 1 table; v2: correction of some web links; v3: new Section 3 with a description of the ILC simulation framework put in place for Snowmass

Physical review letters 124(4), 041804 (2020). doi:10.1103/PhysRevLett.124.041804, We present the possibility that the seesaw mechanism with thermal leptogenesis can be tested using the stochastic gravitational background. Achieving neutrino masses consistent with atmospheric and solar neutrino data, while avoiding nonperturbative couplings, requires right handed neutrinos lighter than the typical scale of grand unification. This scale separation suggests a symmetry protecting the right-handed neutrinos from getting a mass. Thermal leptogenesis would then require that such a symmetry be broken below the reheating temperature. We enumerate all such possible symmetries consistent with these minimal assumptions and their corresponding defects, finding that in many cases, gravitational waves from the network of cosmic strings should be detectable. Estimating the predicted gravitational wave background, we find that future space-borne missions could probe the entire range relevant for thermal leptogenesis., Published by APS, College Park, Md.

We present an overview of the capabilities that the International Linear Collider (ILC) offers for precision measurements that probe the Standard Model. First, we discuss the improvements that the ILC will make in precision electroweak observables, both from W boson production and radiative return to the Z at 250 GeV in the center of mass and from a dedicated GigaZ stage of running at the Z pole. We then present new results on precision measurements of fermion pair production, including the production of b and t quarks. We update the ILC projections for the determination of Higgs boson couplings through a Standard Model Effective Field Theory fit taking into account the new information on precision electroweak constraints. Finally, we review the capabilities of the ILC to measure the Higgs boson self-coupling., Comment: 58 pages, 8 figures, 13 tables; v2: minor corrections to Table 11; v3: typo corrections; v4: additions to the W boson section

We present the possibility that the seesaw mechanism with thermal leptogenesis can be tested using the stochastic gravitational background. Achieving neutrino masses consistent with atmospheric and solar neutrino data, while avoiding non-perturbative couplings, requires right-neutrinos lighter than the typical scale of grand unification. This scale separation suggests a symmetry protecting the right handed neutrinos from getting a mass. Thermal leptogenesis would then require that such a symmetry be broken below the reheating temperature. We enumerate all such possible symmetries consistent with these minimal assumptions and their corresponding defects, finding that in many cases, gravitational waves from the network of cosmic strings should be detectable. Estimating the predicted gravitational wave background we find that future space-borne missions could probe the entire range relevant for thermal leptogenesis., 6 pages, 1 figures, published version