CyberSec Research

An important prediction of inflation is the production of a primordial stochastic gravitational wave background. Observing this background is challenging due to the weakness of the signal and the simultaneous presence of an astrophysical background generated by many unresolved late-time sources. One possible way to distinguish between the two is to examine their anisotropies. In this paper we calculate the primordial correlation function of gravitational wave anisotropies in the cosmological background generated by axion inflation, where the inflaton is a pseudo-Nambu-Goldstone boson coupled to gauge fields. In this scenario, tensor modes arise not only from the standard amplification of vacuum fluctuations present in any inflationary model, but also from the inverse decay process of the produced gauge fields. The correlator of gravitational wave anisotropies consists therefore of two main components: the contribution from vacuum tensor modes and the contribution from tensor modes sourced by the gauge fields. Our analysis shows that, while the former, previously studied in the literature, is negligible, the one arising from the sourced tensor modes, normalized by the fractional energy density at interferometer frequencies, can reach values as large as $\mathcal{O}(10^{-1})$. This result shows that axion inflation can generate large anisotropies with the potential to be observed by gravitational wave detectors within a reasonable time frame.

Cosmic birefringence$-$the rotation of the polarization plane of light as it traverses the universe$-$offers a direct observational window into parity-violating physics beyond the Standard Model. In this work, we revisit the anisotropic component of cosmic birefringence, which leads to the generation of $B$-mode polarization in the cosmic microwave background (CMB). Using an exact theoretical treatment beyond the thin last-scattering surface approximation, we constrain the amplitude of anisotropic birefringence with combined polarization data from SPTpol, ACT, POLARBEAR, and BICEP. The joint analysis yields a best-fit amplitude of $A_{\rm CB} = 0.42^{+0.40}_{-0.34} \times 10^{-4}$, consistent with zero within $2\sigma$, and we place a 95\% confidence-level upper bound of $A_{\rm CB} < 1 \times 10^{-4}$. The constraint is not dominated by any single experiment and remains robust under the inclusion of a possible isotropic rotation angle. These results provide leading constraints on anisotropic cosmic birefringence from CMB $B$-mode polarization and illustrate the potential of upcoming experiments to improve sensitivity to parity-violating effects in the early universe.

Accurate comparisons between theoretical models and experimental data are critical for scientific progress. However, inferred model parameters can vary significantly with the chosen physics model, highlighting the importance of properly accounting for theoretical uncertainties. In this article, we explicitly incorporate these uncertainties using Gaussian processes that model the domain of validity of theoretical models, integrating prior knowledge about where a theory applies and where it does not. We demonstrate the effectiveness of this approach using two systems: a simple ball drop experiment and multi-stage heavy-ion simulations. In both cases incorporating model discrepancy leads to improved parameter estimates, with systematic improvements observed as additional experimental observables are integrated.

We study the forms of CP-violating (CPV) neutral triple gauge couplings (nTGCs) that can be realized via dimension-8 operators in the Standard Model Effective Field Theory (SMEFT). We present a new formulation of the CPV nTGC form factors that is compatible with the spontaneous breaking of the electroweak gauge symmetry, and show how these CPV form factors can be matched consistently with the corresponding dimension-8 CPV nTGC operators in the broken phase. We then study probes of the CPV nTGCs at future high-energy $e^+e^-$ colliders with centre-of-mass energies $\sqrt{s} = (0.25, 0.5,1, 3, 5)$TeV respectively, demonstrating that the $e^{\mp}$ beam polarizations can help to improve the sensitivities of probes of the nTGCs. We estimate that the sensitivities for probing the new physics scales of the nTGCs can range from ${O}(\rm{TeV})$ at a 250GeV $e^+e^-$ collider to ${O}(10\rm{TeV})$ at a 5TeV $e^+e^-$ collider, and that the sensitivities to form factors range from ${O}(10^{-4})$ to ${O}(10^{-8})$.

Fermionic dark matter absorption on nuclear targets via neutral current interactions is explored using a non-relativistic effective field theory framework. An analysis of data from the PICO-60 C$_{3}$F$_{8}$ bubble chamber sets leading constraints on spin-independent absorption for dark matter masses below 23 MeV/$\textit{c}^2$ and establishes the first limits on spin-dependent absorptive interactions. These results demonstrate the sensitivity of bubble chambers to low-mass dark matter and underscore the importance of absorption searches in expanding the parameter space of direct detection experiments.

Precision measurements of Higgs boson differential production cross sections are a key tool to probe the properties of the Higgs boson and test the standard model. New physics can affect both Higgs boson production and decay, leading to deviations from the distributions that are expected in the standard model. In this paper, combined measurements of differential spectra in a fiducial region matching the experimental selections are performed, based on analyses of four Higgs boson decay channels ($\gamma\gamma$, ZZ$^{(*)}$, WW$^{(*)}$, and $\tau\tau$) using proton-proton collision data recorded with the CMS detector at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. The differential measurements are extrapolated to the full phase space and combined to provide the differential spectra. A measurement of the total Higgs boson production cross section is also performed using the $\gamma\gamma$ and ZZ decay channels, with a result of 53.4$^{+2.9}_{-2.9}$ (stat)$^{+1.9}_{-1.8}$ (syst) pb, consistent with the standard model prediction of 55.6 $\pm$ 2.5 pb. The fiducial measurements are used to compute limits on Higgs boson couplings using the $\kappa$-framework and the SM effective field theory.

In this proceedings contribution, I briefly summarize various aspects that are important in the discussions of new physics searches with novel scalar states, at current and future colliders. In particular, I give a brief glance on the status of two Higgs doublet models, and discuss multi-scalar production as well as interference effects in Di-Higgs searches. I also mention searches of new scalar final states at possible Higgs factories.

We compute a complete set of the two-loop Feynman integrals that are required for the next-to-next-to-leading order QCD corrections to on-shell top-pair production in association with a $W$ boson at hadron colliders in the leading colour approximation. These Feynman integrals also contribute to Higgs or $Z$-boson production in association with a top pair. We employ the method of differential equations (DEs), facilitated by the use of finite field methods to handle the algebraic complexity stemming from the seven-scale kinematics. The presence of the top quark in the virtual propagators, in addition to the mass of the external $W$ boson, gives rise to nested square roots and three elliptic curves. We obtain DEs that depend at most quadratically on the dimensional regulator $\epsilon$ for sectors where these analytic structures appear, and are $\epsilon$-factorised otherwise. We express the DEs in terms of a minimal set of differential one-forms, separating the logarithmic ones. We solve the DEs numerically in the physical kinematic region, with the method of generalised power series expansions.

We demonstrate the prompt-delayed signals induced by knockout neutrons from the quasi-elastic scattering in neutrino experiments provides a new avenue for detecting light dark matter. As an illustration, we consider the detection of atmospheric dark matter in the liquid scintillator detectors. The results show that the constraint on the DM-nucleon interaction from KamLAND is approximately one order of magnitude more stringent than those obtained from the elastic nuclear recoil signals in dark matter direct detection experiments. Furthermore, a larger volume neutrino experiment, such as JUNO, is expected to significantly enhance the light dark matter detection sensitivity through the quasi-elastic scattering.

It is well-known that the back-to-back (correlation) limit of inclusive quark-antiquark dijet production in unpolarized high energy electron-proton collisions can probe the Weizs\"{a}cker-Williams (WW) gluon transverse momentum-dependent distribution (TMD) at small $x$ \cite{Dominguez:2010xd, Dominguez:2011wm}. In this paper, we consider a helicity-dependent version of the same process: we study the double-spin asymmetry for inclusive quark-antiquark dijet production in longitudinally polarized electron-proton scattering at high energies. We show that in the back-to-back limit this process probes the WW gluon helicity TMD. Furthermore, we derive the small-$x$ evolution equation for the operator related to the WW gluon helicity distribution. We find that in the double-logarithmic approximation and in the large-$N_c$ limit, the small-$x$ asymptotics of the WW gluon helicity distribution is governed by exactly the same evolution equation as that for the dipole gluon helicity distribution. The longitudinal double-spin asymmetry for inclusive dijet production in the longitudinally polarized electron-proton collisions can thus test the small-$x$ helicity evolution equations and facilitate constraining the initial conditions for phenomenology based on these equations.

We study the Quantum Chromodynamics (QCD) phase transitions in the complex chemical potential plane in the framework of Dyson-Schwinger equation approach, in the presence of a constant gluonic background field that represents confining dynamics. We solve the quark gap equation and the background field equation self consistently, which allows us to directly explore the confinement phase transition and furthermore, evaluate the impact of the back-coupling of confinement on chiral symmetry breaking. Moreover, within such a coupled framework towards the complex chemical potential region, we demonstrate the emergence of Roberge-Weiss (RW) symmetry and investigate the trajectory of Lee-Yang edge singularities (LYES). Our analysis reveals that the LYES scaling behavior is similar to our previous findings without the background field condensate. However, a significant difference from our earlier work is that the trajectory of LYES terminates when the imaginary part of the singularity becomes $1/3 \, \pi T$. We elaborate that this cut-off behavior is caused by the RW symmetry that is symmetric to the imaginary chemical potential $\mu_i=1/3 \, \pi T$.

Describing neutrino masses using the inverse seesaw mechanism with discrete flavor symmetry imposed through modular forms provides a testable framework at TeV scales with fewer parameters. However, $S_3$, the smallest modular group, remains relatively underexplored. In this work, we construct the minimal supersymmetric inverse seesaw model based on the modular $S_3$ flavor symmetry. In our model, the light neutrino mass matrix depends on 6 real parameters: the complex modulus, an overall scale for light neutrino mass, a real ratio and a complex ratio of Yukawa coupling. Thanks to its minimality, our model offers various definite predictions: the lightest neutrino is massless, the neutrino masses are inverted ordering, the sum of the three light neutrino masses ($\sum_i m_i$) is 100 meV, the effective mass for the end point of the beta decay spectrum is 50 meV, the effective mass for neutrinoless double beta decay ($m_{ee}$) is in the range $38-58$ meV. In particular, the predicted values for $\sum_i m_i$ and $m_{ee}$ from our model are within reach of the next generation experiments. Our model also predicts radiative lepton flavor violating decays $\ell\to\ell'\gamma$ which are compatible with experimental constraints.

Recent results from the Atacama Cosmology Telescope (ACT) indicate a scalar spectral index $n_s \simeq 0.9743$, in excellent agreement with the prediction of linear inflation. However, the corresponding tensor-to-scalar ratio $r \simeq 0.0667$ is in tension with current observational bounds. In this work, we investigate how this tension can be alleviated in the Palatini formulation of gravity. We consider two classes of models based on simple monomial potentials: (i) models with a non-minimal coupling between the inflaton and gravity, and (ii) models including an $\alpha R^2$ term. In the first case, we find that a quadratic potential with a linear non-minimal coupling leads to the linear inflation attractor, with $r$ suppressed as $\xi$ increases. In the second case, we show that a linear potential can yield values of $r$ consistent with observations for sufficiently large $\alpha$. Our results demonstrate that simple monomial models can remain compatible with current observational constraints when embedded in the Palatini framework.

We consider a two-component dark matter model with $Z_2 \times Z_4$ symmetry, where a singlet scalar $S$ and a Majorana fermion $\chi$ are introduced as dark matter candidates. We also introduce another singlet scalar $S_0$ with a non-zero vacuum expectation value to the SM so that the fermion dark matter can obtain mass after spontaneous symmetry breaking. We have a new Higgs boson in the model and in the case of the decoupling limit, the fermion dark matter production is only determined by $S$ and the new Higgs boson. The mass hierarchy of these new particles can make a difference in the reaction rate of dark matter annihilation processes, contributing to different viable parameter spaces for different mass orderings. We randomly scanned the parameter space with six various cases under relic density constraint and found that when $\chi$ is the lightest among the dark sector, $\chi$ production is generated via the so-called forbidden channels. Moreover, we consider the combined limits arising from Higgs invisible decay, dark matter relic density and direct detection constraints. Within the chosen parameter space, direct detection results put the most stringent constraint, and we have a more flexible value for the scalar dark matter mass when the mass of $\chi$ is not smaller than the new Higgs boson mass.

We develop a formalism, based on spinor-helicity techniques, to generalize the formulation of partial wave unitarity bounds. We discuss unitarity bounds for $N \to M$ (with $N,M \geq 2$) scattering processes -- relevant for high-energy future colliders -- and spin-2 or higher-spin theories -- relevant for effective field theories of gravity -- that are not approachable by standard methods. Moreover, we emphasize the power and complementarity of positivity and partial wave unitarity bounds to constrain the parameter space of effective field theories.

We study a dark energy model composed of a bare negative cosmological constant and a single ultra-light axion, motivated by the string axiverse. Assuming that intelligent observers can exist and observe an accelerating universe, we derive nontrivial constraints on both the axion mass and the bare cosmological constant. The axion mass is bounded from above to avoid fine-tuning of the initial misalignment angle near the hilltop, and from below because extremely light axions would require the bare cosmological constant to be unnaturally close to zero to achieve accelerated expansion. As a result, the anthropically allowed axion mass range typically lies around $m = \mathcal{O}(10)\, H_0$ for a decay constant close to the Planck scale, where $H_0$ is the observed value of the Hubble constant. In this framework, the dark energy equation of state parameter $w_0$ generically deviates from $-1$ by $\mathcal{O}(0.1)$, providing a natural explanation for why $w \ne -1$ may be expected. This outcome is intriguingly consistent with recent DESI hints of time-varying dark energy, and offers a compelling anthropic explanation within the $\Lambda$ + axion framework.

We explore the application of the exact Wentzel-Kramers-Brillouin (WKB) analysis to two-level Floquet systems and establish a systematic procedure to calculate the quasi-energy and Floquet effective Hamiltonian. We show that, in the exact-WKB analysis, the quasi-energy and Floquet effective Hamiltonian can be expressed in terms of cycle integrals (Voros symbol), which characterize monodromy matrices for Schr\"odinger-type differential equations governing two-level Floquet systems. We analytically evaluate the cycle integrals using the low-frequency expansion and derive both perturbative and non-perturbative corrections to the quasi-energy and Floquet effective Hamiltonian. To verify the accuracy of our results, we compare them with numerical calculations and analyze resonant oscillations, which reveal non-perturbative features that cannot be captured by the perturbative expansion.

We analyse HERA data on leading neutron production in one-pion exchange approximation. The dipole-pion cross section as function of transverse separation $\bf r$ at small Bjorken variable $\beta$ is parameterized within the bSat model. The evolution of the dipole-pion cross section is performed applying the Laplace transformation technique. We demonstrate that geometric scaling for the dipole-pion cross section hold approximately within a wide kinematic region of $rQ_s$. The geometrical scaling is improved applying the evolution method. That is compared with the constituent quark picture and the color dipole BFKL expansion. The cross section saturates at large dipole sizes.