According to the standard model of cosmology, the early universe was dominated by radiation or nonrelativistic matter in several eras of its history. However, many cosmological calculations involving particle processes commonly use Minkowskian results; although, for more precise treatment, quantum field theory in curved spacetime is needed. This paper aims to fill this gap by presenting decay rates for matter and radiation dominated universes in this more precise treatment. We provide a study of the average decay rates for a process where a conformally coupled massive scalar field decays into massless scalar particles. It is found that the presence of a curved spacetime modifies the Minkowskian result considerably for early times but asymptotically only by an additive term proportional to the inverse of the mass and interaction time. Thus, the correction is small for large time scales, but on the time scales of the order of $m\sim t$, the relative correction term may be of importance.

In this work, we first solve complex Morse flow equations for the simplest case of a bosonic harmonic oscillator to discuss localization in the context of Picard-Lefschetz theory. We briefly touch on the exact non-BPS solutions of the bosonized supersymmetric quantum mechanics on algebraic geometric grounds and report that their complex phases can be accessed through the cohomology of WKB 1-form of the underlying singular spectral curve subject to necessary cohomological corrections for nonzero genus. Motivated by Picard-Lefschetz theory, we write down a general formula for the index of $\mathcal{N}=4$ quantum mechanics with background $R$-symmetry gauge fields. We conjecture that certain symmetries of the refined Witten index and singularities of the moduli space may be used to determine the correct intersection coefficients. A few examples, where this conjecture holds, are shown in both linear and closed quivers with rank-one quiver gauge groups. The $R$-anomaly removal along the “Morsified” relative homology cycles also called “Lefschetz thimbles” is shown to lead to the appearance of Stokes lines. We show that the Fayet-Iliopoulos parameters appear in the intersection coefficients for the relative homology of the quiver quantum mechanics resulting from dimensional reduction of $2d$ $\mathcal{N}=(2,2)$ gauge theory on a circle and explicitly calculate integrals along the Lefschetz thimbles in $\mathcal{N}=4$ $\mathbb{C}{\mathbb{P}}^{k-1}$ model. The Stokes jumping of coefficients and its relation to wall crossing phenomena is briefly discussed. We also find that the notion of “on-the-wall” index is related to the invariant Lefschetz thimbles under Stokes phenomena. An implication of the Lefschetz thimbles in constructing knots from quiver quantum mechanics is indicated.

By using a bottom-up reconstruction technique for nonminimally coupled scalar-tensor theories, we realize the Einstein frame attractor cosmologies in the $\mathrm{\Omega }(\varphi )$-Jordan frame. For our approach, what is needed for the reconstruction method to work is the functional form of the nonminimal coupling $\mathrm{\Omega }(\varphi )$ and of the scalar-to-tensor ratio, and also the assumption of the slow-roll inflation in the $\mathrm{\Omega }(\varphi )$-Jordan frame. By appropriately choosing the scalar-to-tensor ratio, we demonstrate that the observational indices of the attractor cosmologies can be realized directly in the $\mathrm{\Omega }(\varphi )$-Jordan frame. We investigate the special conditions that are required to hold true in for this realization to occur, and we provide the analytic form of the potential in the $\mathrm{\Omega }(\varphi )$-Jordan frame. Also, by performing a conformal transformation, we find the corresponding Einstein frame canonical scalar-tensor theory, and we calculate in detail the corresponding observational indices. The result indicates that although the spectral index of the primordial curvature perturbations is the same in the Jordan and Einstein frames, at leading order in the $e$-foldings number, the scalar-to-tensor ratio differs. We discuss the possible reasons behind this discrepancy, and we argue that the difference is due to some approximation we performed to the functional form of the potential in the Einstein frame, in order to obtain analytical results, and also due to the difference in the definition of the $e$-foldings number in the two frames, which is also pointed out in the related literature. Finally, we find the $F(R)$ gravity corresponding to the Einstein frame canonical scalar-tensor theory.

Dark matter annihilation can have a strong impact on many astrophysical processes in the Universe. In the case of Sommerfeld-enhanced annihilation cross sections, the annihilation rates are enhanced at late times, thus enhancing the potential annihilation signatures. We here calculate the Sommerfeld-enhanced annihilation signatures during the epoch of helium reionization, the epoch where helium becomes fully ionized due to energetic photons. When considering the upper limits on the energy injection from the CMB, we find that the resulting abundance of ${\mathrm{He}}^{++}$ becomes independent of the dark matter particle mass. The resulting enhancement compared to a standard scenario is thus 1-2 orders of magnitude higher. For realistic scenarios compatible with CMB constraints, there is no significant shift in the epoch of helium reionization, which is completed between redshifts 3 and 4. While it is thus difficult to disentangle dark matter annihilation from astrophysical contributions (active galactic nuclei), a potential detection of dark matter particles and its interactions using the Large Hadron Collider (LHC) would allow one to quantify the dark matter contribution.

We study tidal stripping of fuzzy dark matter (FDM) subhalo cores using simulations of the Schrödinger-Poisson equations and analyze the dynamics of tidal disruption, highlighting the differences with standard cold dark matter. Mass loss outside of the tidal radius forces the core to relax into a less compact configuration, lowering the tidal radius. As the characteristic radius of a solitonic core scales inversely with its mass, tidal stripping results in a runaway effect and rapid tidal disruption of the core once its central density drops below 4.5 times the average density of the host within the orbital radius. Additionally, we find that the core is deformed into a tidally locked ellipsoid with increasing eccentricities until it is completely disrupted. Using the core mass loss rate, we compute the minimum mass of cores that can survive several orbits for different FDM particle masses and compare it with observed masses of satellite galaxies in the Milky Way.

We study viable small-field Coleman-Weinberg (CW) inflation models with the help of nonminimal coupling to gravity. The simplest small-field CW inflation model (with a low-scale potential minimum) is incompatible with the cosmological constraint on the scalar spectral index. However, there are possibilities to make the model realistic. First, we revisit the CW inflation model supplemented with a linear potential term. We next consider the CW inflation model with a logarithmic nonminimal coupling and illustrate that the model can open a new viable parameter space that includes the model with a linear potential term. We also show parameter spaces where the Hubble scale during the inflation can be as small as ${10}^{-4}\mathrm{GeV}$, 1 GeV, $10^4\mathrm{GeV}$, and $10^8\mathrm{GeV}$ for the number of $e$-folds of 40, 45, 50, and 55, respectively, with other cosmological constraints being satisfied.

Axionlike particles (ALPs) are one promising type of dark matter candidate particle that may generate detectable effects on $\gamma$-ray spectra other than the canonical weakly interacting massive particles. In this work we search for such oscillation effects in the spectra of supernova remnants caused by the photon-ALP conversion, using the Fermi Large Area Telescope data. Three bright supernova remnants, IC443, W44, and W51C, are analyzed. The inclusion of photon-ALP oscillations yields an improved fit to the $\gamma$-ray spectrum of IC443, which gives a statistical significance of $4.2\sigma$ in favor of such spectral oscillation. However, the best-fit parameters of ALPs ($m_a=6.6\mathrm{neV}$, $g_{a\gamma }=13.4\times {10}^{-11}{\mathrm{GeV}}^{-1}$) are in tension with the upper bound ($g_{a\gamma }<6.6\times {10}^{-11}{\mathrm{GeV}}^{-1}$) set by the CAST experiment. It is difficult to explain the results using the systematic uncertainties of the flux measurements. We speculate that the “irregularity” displayed in the spectrum of IC443 may be due to the superposition of the emission from different parts of the remnant.

We consider the prospects for multiple dark matter direct detection experiments to determine if the interactions of a dark matter candidate are isospin-violating. We focus on theoretically well-motivated examples of isospin-violating dark matter (IVDM), including models in which dark matter interactions with nuclei are mediated by a dark photon, a $Z$, or a squark. We determine that the best prospects for distinguishing IVDM from the isospin-invariant scenario arise in the cases of dark photon–or $Z$-mediated interactions, and that the ideal experimental scenario would consist of large exposure xenon- and neon-based detectors. If such models just evade current direct detection limits, then one could distinguish such models from the standard isospin-invariant case with two detectors with of order 100 ton-year exposure.

We explore the potential of a selected model of radiative neutrino masses to be implemented in a renormalizable SU(5) unification framework. The Zee-type model under consideration uncovers the SU(5) representations in which the new fields are embedded and which may contain also other light states leading to the unification of gauge couplings. We perform an exhaustive search which reveals specific patterns of new states and demonstrate that such patterns are consistent with a general choice of relevant scalar potential. It turns out that all of the specific scenarios which lead to successful unification include the colored scalars testable at the LHC.

We propose a strategy for distinguishing the Dirac/Majorana character of heavy neutrinos with masses below the $W$-boson mass, using purely leptonic decays at the LHC. The strategy makes use of a forward-backward asymmetry of the opposite-charge lepton in the $W^{+}\to l^{+}{l}^{+}{l}^{\prime -}\nu$ decay. In order to check the experimental feasibility of the model, we show—through a numerical analysis and for different ranges of the heavy neutrino masses—that in the decay $W^{+}\to e^{+}{e}^{+}{\mu }^{-}\nu$ one can distinguish the positron from the $W$ decay from the positron coming from the heavy neutrino. Finally, we estimate the number of events at the LHC Run II for a Dirac and Majorana $N$ neutrino with an integrated luminosity of $120{\mathrm{fb}}^{-1}$. Signals can be found if heavy-to-light neutrino mixings are $|U_{N\mu }{|}^2,|U_{Ne}{|}^2\gtrsim {10}^{-6}$.

The R-parity conserving minimal supersymmetric standard model (MSSM) in light of the decay $B_s\to {\mu }^{+}{\mu }^{-}$ with near-standard model branching ratio is an interesting platform for studying the complementarity between direct and indirect searches for beyond the standard model physics. Based on this, we have analysed the possible impact of the $B_s\to {\mu }^{+}{\mu }^{-}$ observation on the posterior sample from the global fit of a 30-parameter MSSM (MSSM-30), and the related Wilson coefficients. The MSSM-30 is a systematically constructed, symmetry-guided, MSSM parameterisation, as opposed to the traditional frames (e.g., pMSSM) with crude treatment of flavor violation parameters. This paper illustrates why phenomenological frames like the MSSM-30 should be preferred to study flavor physics. For the current and future B-physics experimental precision, such a consideration is crucial for suitably assessing supersymmetric contributions to flavor observables.

We investigate the Sivers asymmetry in the pion-induced single polarized Drell-Yan process in the theoretical framework of the transverse momentum dependent factorization up to next-to-leading logarithmic order of QCD. Within the TMD evolution formalism of parton distribution functions, the recently extracted nonperturbative Sudakov form factor for the pion distribution functions as well as the one for the Sivers function of the proton are applied to numerically estimate the Sivers asymmetry in the ${\pi }^{-}p$ Drell-Yan at the kinematics of the COMPASS at CERN. In the low $b$ region, the Sivers function in $b$-space can be expressed as the convolution of the perturbatively calculable hard coefficients and the corresponding collinear correlation function, of which the Qiu-Sterman function is the most relevant one. The effect of the energy-scale dependence of the Qiu-Sterman function to the asymmetry is also studied. We find that our prediction on the Sivers asymmetries as functions of $x_p$, $x_{\pi }$, $x_F$ and $q_{\perp }$ is consistent with the recent COMPASS measurement.

Using $e^{+}{e}^{-}$ collision data collected with the BESIII detector at the BEPCII collider corresponding to an integrated luminosity of $5.2{\mathrm{fb}}^{-1}$ at center-of-mass energies ($\sqrt{s}$) from 4.009 to 4.600 GeV, the process $e^{+}{e}^{-}\to {\pi }^0{\pi }^0\psi (3686)$ is studied for the first time. The corresponding Born cross sections are measured and found to be half of those of the reaction $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\psi (3686)$. This is consistent with the expectation from isospin symmetry. Furthermore, the Dalitz plots for ${\pi }^0{\pi }^0\psi (3686)$ are accordant with those of ${\pi }^{+}{\pi }^{-}\psi (3686)$ at all energy points, and a neutral analog to the structure in ${\pi }^{\pm }\psi (3686)$ around $4040\mathrm{MeV}/c^2$ first observed at $\sqrt{s}=4.416\mathrm{GeV}$ is observed in the isospin neutral mode at the same energy.

Cohen and Glashow introduced the notion of very special relativity as viable space-time symmetry of elementary particle physics. As a natural generalization of their idea, we study the subgroup of the conformal group, dubbed very special conformal symmetry, which is an extension of the very special relativity. We classify all of them and construct field theory examples as well as holographic realization of the very special conformal field theories.

The $D$-term is defined through matrix elements of the energy-momentum tensor, similarly to mass and spin, yet this important particle property is experimentally not known any fermion. In this work we show that the $D$-term of a spin $\frac{1}{2}$ fermion is of dynamical origin: it vanishes for a free fermion. This is in pronounced contrast to the bosonic case where already a free spin-0 boson has a non-zero intrinsic $D$-term. We illustrate in two simple models how interactions generate the $D$-term of a fermion with an internal structure, the nucleon. All known matter is composed of elementary fermions. This indicates the importance to study this interesting particle property in more detail, which will provide novel insights especially on the structure of the nucleon.

We use the IR fixed point predictions for gauge couplings and the top Yukawa coupling in the minimal supersymmetric model (MSSM) extended with vectorlike families to infer the scale of vectorlike matter and superpartners. We quote results for several extensions of the MSSM and present results in detail for the MSSM extended with one complete vectorlike family. We find that for a unified gauge coupling ${\alpha }_G>0.3$ vectorlike matter or superpartners are expected within 1.7 TeV (2.5 TeV) based on all three gauge couplings being simultaneously within 1.5% (5%) from observed values. This range extends to about 4 TeV for ${\alpha }_G>0.2$. We also find that in the scenario with two additional large Yukawa couplings of vectorlike quarks the IR fixed point value of the top Yukawa coupling independently points to a multi-TeV range for vectorlike matter and superpartners. Assuming a universal value for all large Yukawa couplings at the grand unified theory scale, the measured top quark mass can be obtained from the IR fixed point for $\tan \beta \simeq 4$. The range expands to any $\tan \beta >3$ for significant departures from the universality assumption. Considering that the Higgs boson mass also points to a multi-TeV range for superpartners in the MSSM, adding a complete vectorlike family at the same scale provides a compelling scenario where the values of gauge couplings and the top quark mass are understood as a consequence of the particle content of the model.

We point out the importance of the decay channels $A\to Zh$ and $H\to VV$ in the wrong-sign limit of the two-Higgs-doublet model (2HDM) of type II. They can be the dominant decay modes at moderate values of $\tan \beta$, even if the (pseudo)scalar mass is above the threshold where the decay into a pair of top quarks is kinematically open. Accordingly, large cross sections $pp\to A\to Zh$ and $pp\to H\to VV$ are obtained and currently probed by the LHC experiments, yielding conclusive statements about the remaining parameter space of the wrong-sign limit. In addition, mild excesses—as recently found in the ATLAS analysis $b\overline{b}\to A\to Zh$—could be explained. The wrong-sign limit makes other important testable predictions for the light Higgs boson couplings.

We explore the low-scale implications of the Pati-Salam Model including the TeV scale right-handed neutrinos interacting and mixing with the MSSM fields through the inverse seesaw (IS) mechanism in light of the muon anomalous magnetic moment (muon $g-2$) resolution and highlight the solutions which are compatible with the quasi-Yukawa unification condition (QYU). We find that the presence of the right-handed neutrinos causes heavy smuons as $m_{\tilde{\mu }}\gtrsim 800\mathrm{GeV}$ in order to avoid tachyonic staus at the low scale. On the other hand, the sneutrinos can be as light as about 100 GeV, and along with the light charginos of mass $\lesssim 400\mathrm{GeV}$, they can yield such large contributions to muon $g-2$ that the discrepancy between the experiment and the theory can be resolved. These solutions also require $m_{{\tilde{\chi }}_1^{\pm }}\lesssim 400\mathrm{GeV}$ and $m_{{\tilde{\chi }}_1^0}\lesssim 200$. We also discuss such light chargino and neutralino along with the light stau ($m_{\tilde{\tau }}\gtrsim 200\mathrm{GeV}$) in the light of current LHC results. Besides, the gluino mass lies in a range $\sim [2.5–3.5]\mathrm{TeV}$, which is tested in near future experiments. In addition, the model predicts relatively light Higgsinos ($\mu \lesssim 700\mathrm{GeV}$); hence, the second chargino mass is also light enough ($\lesssim 700\mathrm{GeV}$) to contribute to muon $g-2$. Light Higgsinos also yield less fine-tuning at the electroweak scale, and the regions compatible with muon $g-2$ restrict ${\mathrm{\Delta }}_{\mathrm{EW}}\lesssim 100$ strictly, and this region also satisfies the QYU condition. In addition, the ratios among the Yukawa couplings should be $1.8\lesssim y_t/y_b\lesssim 2.6$, $y_{\tau }/y_b\sim 1.3$ to yield correct fermion masses. Even though the right-handed neutrino Yukawa coupling can be varied freely, the solutions bound its range to $0.8\lesssim y_{\nu }/y_b\lesssim 1.7$.

We study the impact of fermionic dark matter (DM) on projected Higgs precision measurements at the Circular Electron Positron Collider (CEPC), including the one-loop effects on the $e^{+}{e}^{-}\to Zh$ cross section and the Higgs boson diphoton decay, as well as the tree-level effects on the Higgs boson invisible decay. As illuminating examples, we discuss two UV-complete DM models, whose dark sector contains electroweak multiplets that interact with the Higgs boson via Yukawa couplings. The CEPC sensitivity to these models and current constraints from DM detection and collider experiments are investigated. We find that there exist some parameter regions where the Higgs measurements at the CEPC will be complementary to current DM searches.