We show how several properties of the QCD axion can be extracted at high precision using only first principle computations. By combining NLO results obtained in chiral perturbation theory with recent Lattice full potential, its mass and coupling to photons reconstructed percent precision. Axion couplings nucleons also derived reliably, uncertainties smaller than ten percent. The approach presented here allows further improved as on light quark masses effective are reduced. compute finite...

We study the system of axion strings that forms in early Universe if Peccei-Quinn symmetry is restored after inflation. Using numerical simulations, we establish existence an asymptotic solution to which attracted independently initial conditions. detail properties this solution, including average number per Hubble patch, distribution loops and long strings, way different types radiation are emitted, shape spectrum axions produced. find clear evidence logarithmic violations scaling attractor...

A bstract We study supernova cooling constraints on new light scalars that mix with the Higgs, couple only to nucleons, or leptons. show in all these cases masses smaller than plasma frequency core are efficiently produced by resonant mixing in-medium longitudinal degree of freedom photon. The resulting bounds free from uncertainties associated rate emission scalar nucleon-nucleon scatterings, which would otherwise badly affect Higgs-mixed and nucleophilic scenarios. Heavier Higgs nucleons...

Strong constraints on the coupling of new light particles to Standard Model (SM) arise from their production in hot cores stars, and effects this stellar cooling. For which have an effective in-medium mixing with photon, plasma can result parametrically different rates those obtained a naive calculation. Taking these previously-neglected contributions into account, we make updated estimates for cooling bounds scalars vectors variety SM couplings. In particular, improve (m ≲ keV) electrons or...

It has been suggested that certain antiferromagnetic topological insulators contain axion quasiparticles (AQs), and such materials could be used to detect dark matter (DM). The AQ is a longitudinal spin fluctuation coupled the electromagnetic Chern-Simons term, which, in presence of an applied magnetic field, leads mass mixing between electric field. boundary conditions transmission reflection coefficients are computed. A model for including losses into this system presented, resulting...

A bstract We study the spectrum of gravitational waves produced by a first order phase transition in hidden sector that is colder than visible sector. In this scenario, bubbles vacuum can be nucleated through either thermal fluctuations or quantum tunnelling. If cold undergoes thermally induced transition, amplitude wave signal will suppressed and its peak frequency shifted compared to if temperatures were equal. This could lead signals range would otherwise ruled out constraints from big...

Abstract If the Peccei-Quinn symmetry associated to an axion has ever been restored after inflation, strings inevitably produce a contribution stochastic gravitational wave background. Combining effective field theory analysis with numerical simulations, we show that resulting spectrum logarithmic deviations from scale invariant form amplitude is significantly enhanced at low frequencies. As result, single ultralight axion-like particle decay constant larger than 10 14 GeV and any mass...

Abstract Any new vector boson with non-zero mass (a 'dark photon' or 'Proca boson') that is present during inflation automatically produced at this time from vacuum fluctuations and can comprise all a substantial fraction of the observed dark matter density, as shown by Graham, Mardon, Rajendran. We demonstrate, utilising both analytic numerical studies, such scenario implies an extremely rich substructure arising purely interplay gravitational interactions quantum effects. Due to remarkable...

A bstract We show that if dark matter consists of QCD axions in the post-inflationary scenario more than ten percent it efficiently collapses into Bose stars at matter-radiation equality. Such a result is mostly independent present uncertainties on axion mass. This large population solitons, with asteroid masses and Earth-Moon distance sizes, might plausibly survive until today, potentially interesting implications for phenomenology experimental searches.

We investigate the physics of dark matter models featuring composite bound states carrying a large conserved "nucleon" number. The properties sufficiently nuclei may obey simple scaling laws, and we find that this can determine number distribution resulting from Big Bang Dark Nucleosynthesis. For plausible asymmetric matter, nucleon number, e.g. > 10^8, be synthesised, with taking one two characteristic forms. If small-nucleon-number fusions are fast, takes on logarithmically-peaked,...

We study the contribution to QCD axion dark matter abundance that is produced by string defects during so-called scaling regime. Clear evidence of violations found, most conservative extrapolation which strongly suggests a large number axions from strings. In this regime, nonlinearities at around scale are shown play an important role in determining final abundance. The overall result lower bound on mass post-inflationary scenario substantially stronger than naive one misalignment.

A bstract We propose a new regime of minimal QCD axion dark matter that lies between the pre- and post-inflationary scenarios, such Peccei-Quinn (PQ) symmetry is restored only on sufficiently large spatial scales. This leads to novel cosmological evolution, in which strings domain walls re-enter horizon annihilate later than ordinary regime, possibly even after crossover. Such dynamics can occur if PQ by inflationary fluctuations, i.e. Hubble parameter during inflation H I larger breaking...

We investigate the interactions of large composite dark matter (DM) states with Standard Model (SM) sector. Elastic scattering SM nuclei can be coherently enhanced by factors as A^2, where A is number constituents in state (there exist models which DM very > 10^8 may realised). This enhancement, for a given direct detection event rate, weakens expected signals at colliders up to 1/A. Moreover, spatially extended nature leads an additional, characteristic, form factor modifying momentum...

A bstract scalar particle with a relic density set by annihilations through Higgs portal operator is simple and minimal possibility for dark matter. However, assuming thermal cosmological history this model ruled out over most of parameter space collider direct detection constraints. We show that in theories non-thermal matter viable wide range masses values the coupling, evading existing limits. In particular, we focus on string theory motivated scenario period domination due to light...

Hidden sector glueball dark matter is well motivated by string theory, compactifications of which often have extra gauge groups uncoupled to the visible sector. We study dynamics glueballs in theories with a period late time primordial domination followed low final reheating temperature due gravitationally coupled modulus. Compared scenarios high temperature, required relic abundance possible higher hidden confinement scales, and less extreme differences entropy densities sectors. Both these...

We analyze theories that do not have a de Sitter vacuum and cannot lead to slow-roll quintessence, but which nevertheless support transient era of accelerated cosmological expansion due interactions between scalar <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi>ϕ</a:mi></a:mrow></a:math> either hidden sector thermal bath, evolves as dark radiation, or an extremely light component matter. show simple models can explain the present-day energy Universe...

We study theories which naturally select a vacuum with parametrically small Electroweak Scale due to finite temperature effects in the early universe. In particular, there is scalar an approximate shift symmetry broken by technically natural coupling Higgs, and dependent potential. As of universe drops, follows minimum its potential altering Higgs mass squared parameter. The also has periodic amplitude proportional expectation value, traps it Scale. required dependence can occur through...

A bstract An axion-like-particle (ALP) in the post-inflationary scenario with domain wall number N &gt; 1 can be dark matter if residual ℤ symmetry has a small explicit breaking. Although we cannot determine full dynamics of system reliably, provide evidence that such an ALP account for observed abundance while having relatively decay constant and consequently possibly large coupling to photons. In particular, walls per Hubble patch around time when they form using numerical simulations...

In the simplest models of asymmetric dark matter (ADM) annihilation signals are not expected, since DM is non-self-conjugate and relic density anti-DM negligible. We investigate a new class in which symmetric component, 'low-mass' 1-10 GeV regime favoured for linking baryon asymmetries, repopulated through decays. find that, without significant velocity dependence cross section, observational constraints generally force these decays to be (cosmologically) slow. These late can give rise...

We study models in which the 750 GeV diphoton excess is due to a scalar decaying two pseudo-Nambu-Goldstone bosons that subsequently decay into pairs of highly boosted photons, misidentified as individual photons. Performing model independent analysis we find that, with axion mass around $200$ MeV, this class theories can naturally explain observed signal large width, without violating monojet constraints. At same time requirement prompt be satisfied only relatively axion-photon coupling,...

We study the four-dimensional effective theory arising from ten-dimensional heterotic supergravity compactified on manifolds with torsion. In particular, given superpotential appropriately corrected at O(α′) to account for Green-Schwarz anomaly cancellation mechanism, we investigate properties of Minkowski vacua this theory. Considering restrictions F-terms and D-terms identify infinitesimal massless moduli space show that it agrees results have recently been obtained a perspective where...

We initiate the application of Hamiltonian truncation methods to solve strongly coupled QFTs in $d=2+1$. By analysing perturbation theory with a regulator, we pinpoint challenges such an approach and propose way that these can be addressed. This enables us formulate Truncation for ${\ensuremath{\phi}}^{4}$ $d=2+1$, study its spectrum at weak strong coupling. The results obtained agree well predictions weak/strong self-duality possessed by theory. interaction is relevant UV divergent...

An ultralight axion with <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi>C</a:mi><a:mi>P</a:mi></a:mrow></a:math> violating interactions a dark sector and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mi>C</c:mi><c:mi>P</c:mi></c:mrow></c:math> preserving the visible can act as novel portal between matter Standard Model. In such theories, sources an field extending over entire galaxy, gradient of which be searched for...