Motivated by the fact that a sharply peaked curvature spectrum is often considered in the literature, we examine theoretical constraints on the sharpness of such a spectrum. In particular, we show that the sharply peaked curvature power spectrum, originating from the enhancement of subhorizon perturbations during inflation, is significantly constrained by energy conservation. While the constraints do not depend on the exact form of inflaton potential, we also study concrete inflaton potentials that realize a sharply peaked curvature spectrum and how theoretical limits are saturated in these cases.

We characterize magnetic fields produced during electroweak symmetry breaking by nondynamical numerical simulations based on the Kibble mechanism. The generated magnetic fields were thought to have an energy spectrum $\propto k^3$ for small wave numbers $k$, but here we show that it is actually a spectrum $\propto k^4$ along with characteristic fluctuations in the magnetic helicity. Using scaling results from magnetohydrodynamics simulations for the evolution and assuming that the initial magnetic field is coherent on the electroweak Hubble scale, we estimate the magnetic field strength to be $\sim {10}^{-13}\mathrm{G}$ on kpc scales at the present epoch for nonhelical fields. For maximally helical fields we obtain $\sim {10}^{-10}\mathrm{G}$ on Mpc scales. We also give scalings of these estimates for partially helical fields.

The mass transfer process is prevalent during the inspiral phase of compact binary systems. Our study focuses on systems comprising low-mass white dwarfs, particularly in neutron star-white dwarf binaries and double white dwarf binaries, where a stable mass transfer process occurs at low frequencies. By analyzing the evolution of gravitational wave frequencies in the presence of mass transfer within quasicircular orbits, we derive an analytical expression for the time-dependent frequency across different frequency bands and the waveforms emitted by compact binaries. Considering gravitational waves emitted by compact binaries in the $1\sim 10\mathrm{mHz}$ band, based on the Fisher analysis, we find that the mass transfer rate can be measured as accurately as ${10}^{-7}{M}_{\odot }/\mathrm{year}$ by space-based gravitational-wave detectors with a signal-to-noise ratio of the order of ${10}^3$. Including the mass transfer effect in the waveforms provides a new possibility to measure the individual masses of double white dwarf binaries. The relative error of measured white dwarf masses can be down to the order of 0.01.

The Laser Interferometer Space Antenna (LISA) will be the first space-based gravitational wave (GW) observatory. It will measure gravitational wave signals in the frequency regime from 0.1 mHz to 1 Hz. The success of these measurements will depend on the suppression of the various instrument noises. One important noise source in LISA will be tilt-to-length (TTL) coupling. Here, it is understood as the coupling of angular jitter, predominantly from the spacecraft, into the interferometric length readout. The current plan is to subtract this noise in flight in postprocessing as part of a noise minimization strategy. It is crucial to distinguish TTL coupling well from the GW signals in the same readout to ensure that the noise will be properly modeled. Furthermore, it is important that the subtraction of TTL noise will not degrade the GW signals. In the present manuscript, we show on simulated LISA data and for four different GW signal types that the GW responses have little effect on the quality of the TTL coupling fit and subtraction. Also, the GW signal characteristics were not altered by the TTL coupling subtraction.

Gamma/hadron discrimination in ground-based gamma-ray observatories at the sub-TeV energy range is challenging as traditional muon-based methods become less effective at lower energies. This work explores a novel gamma/hadron discrimination method for extensive air shower arrays that analyzes the shower signal footprint patterns using a state-of-the-art pretrained vision transformer. The resilience of the method to background noise, such as atmospheric muons and low-energy proton showers, along with its adaptability to different zenith angles and array configurations, demonstrates its potential for application in current and future ground-based gamma-ray observatories.

The promise of multimessenger astronomy relies on the rapid detection of gravitational waves at very low latencies [$\mathcal{O}(1\mathrm{s})$] in order to maximize the amount of time available for follow-up observations. In recent years, neural networks have demonstrated robust nonlinear modeling capabilities and millisecond-scale inference at a comparatively small computational footprint, making them an attractive family of algorithms in this context. However, integration of these algorithms into the gravitational-wave astrophysics research ecosystem has proven nontrivial. Here, we present a machine-learning-based pipeline for the detection of gravitational waves from compact binary coalescences designed to run in low latency. We demonstrate this pipeline to have a fraction of the latency of traditional matched filtering search pipelines while achieving state-of-the-art sensitivity to higher-mass stellar binary black holes.

In this study, we investigate the impact of new Large Hadron Collider (LHC) inclusive jet and dijet measurements on parton distribution functions (PDFs) that describe the proton structure, with a particular focus on the gluon distribution at large momentum fraction, $x$, and the corresponding partonic luminosities. We assess constraints from these datasets using next-to-next-to-leading-order (NNLO) theoretical predictions, accounting for a range of uncertainties from scale dependence and numerical integration. From the scale choices available for the calculations, our analysis shows that the central predictions for inclusive jet production show a smaller scale dependence than dijet production. We examine the relative constraints on the gluon distribution provided by the inclusive jet and dijet distributions, and also explore the phenomenological implications for inclusive $H$, $t\overline{t}$, and $t\overline{t}H$ production at the LHC at 14 TeV.

We present the implementation and results of a new model for the $n$-particle $n$-hole (np-nh) contribution in the NuWro event generator, grounded in the theoretical framework established by the Valencia group in 2020. For the 2p2h component, we introduce a novel nucleon sampling function with tunable parameters to approximate correlations in the momenta of outgoing nucleons. These parameters are calibrated by comparing our results to those of the Valencia model across a range of incoming neutrino energies. In addition, our model incorporates a distinct contribution from the 3p3h mechanism. We discuss the differences between the new NuWro implementation, the original Valencia model, and the previous NuWro version, focusing on the distribution of outgoing nucleon momenta. Finally, we assess the impact of the hadronic model on experimental analyses involving hadronic observables.

The Unruh effect, predicting a thermal reservoir for accelerating systems, calls for a more refined understanding of measurement processes involving quantum systems as thermometers. Conventional models fail to account for the inherent spatial extent of the thermometer, neglecting the complexities associated with accelerated extended quantum systems. Our work builds upon the seminal work of Bell et al. [Z. Phys. C 28, 75 (1985).]. We propose a refined thermometer model incorporating a spin-$1/2$ particle where the spin acts as a temperature indicator. This refined model demonstrates the ability to effectively measure the temperature under specific, realistic conditions, providing a unique value that essentially averages the local Unruh temperatures throughout the extended quantum system acting as the thermometer.

A thorough account of electromagnetic interactions of massive Dirac neutrinos as well as their spin-flavor state in the theoretical formulation of elastic neutrino-nucleon scattering is given. The formalism of neutrino charge, magnetic, electric, and anapole form factors defined as matrices in the mass basis is employed under the assumption of three-neutrino mixing. The flavor and spin change of neutrinos propagating from the source to the detector is taken into account in the form of a spin-flavor density matrix of the neutrino arriving at the detector. The potential effects of the neutrino charge radii, magnetic moments, and spin polarization in the neutrino-nucleon scattering experiments are outlined.

We study $CP$ violation (CPV) in the sneutrino sector within the B-L extension of the minimal supersymmetric Standard Model, wherein an inverse seesaw mechanism has been implemented. CPV arises from the new superpotential couplings in the (s)neutrino sector, which can be complex and the mixing of $CP$ eigenstates induced by those couplings. CPV leads to asymmetries in so-called T-odd observables, but we argue that such asymmetries also lead to a wider distribution of those observables. We look at a final state where a sneutrino decays to a lepton, two jets, and missing transverse momentum at the Future Circular Collider operating in hadron-hadron mode at 100 TeV and with a luminosity of $3{\mathrm{ab}}^{-1}$. In order to exclude the $CP$ conserving scenario we need to improve traditional analysis by introducing boosted decision trees using both standard kinematic variables and T-odd observables and we need $Z^{\prime }$ boson not too much above current bounds as a portal to produce sneutrinos efficiently.

Charge-parity ($CP$) asymmetries in charm decays are extremely suppressed in the Standard Model and may well be dominated by new-physics contributions. The LHCb Collaboration reported the results of direct $CP$ asymmetry measurements in $D^0\to K^{+}{K}^{-}$ and $D^0\to {\pi }^{+}{\pi }^{-}$ decays with unprecedented accuracy: $a_{CP}(K^{+}{K}^{-})=(7.7\pm 5.7)\times {10}^{-4}$ and $a_{CP}({\pi }^{+}{\pi }^{-})=(23.2\pm 6.1)\times {10}^{-4}$, with the latter quantity inferred from the precise measurement of $\mathrm{\Delta }{a}_{CP}=a_{CP}(K^{+}{K}^{-})-a_{CP}({\pi }^{+}{\pi }^{-})=(-15.7\pm 2.9)\times {10}^{-4}$. When interpreted within the Standard Model, these values indicate a breakdown of the approximate $U$-spin symmetry of QCD. If, however, this symmetry holds and the data stem from new physics, other $CP$ asymmetries should be enhanced as well. We derive $CP$ asymmetry sum rules based on SU(3) flavor symmetry for $D$ meson decays into a pair of pseudoscalar mesons as well as a pair of a pseudoscalar and a vector meson for two generic scenarios, with $\mathrm{\Delta }U=0$ and $|\mathrm{\Delta }U|=1$ interactions, respectively. The correlations implied by the sum rules can be used to check the consistency between different measurements and to discriminate between these scenarios with future data. For instance, we find $a_{CP}({\pi }^{+}{K}^{*0})+a_{CP}(K^{+}{\overline{K}}^{*0})=0$ for $\mathrm{\Delta }U=0$ new physics and the opposite relative sign for the $|\mathrm{\Delta }U|=1$ case. One sum rule, connecting four decay modes, holds in both scenarios. We further extend our sum rules to certain differences of $CP$ asymmetries from which the $D$ production asymmetries drop out.

We investigate the time modulation of weak nuclear decays as a method to probe axion dark matter. To this end, we develop a theoretical framework to compute the $\theta$ dependence of weak nuclear decays, including electron capture and $\beta$ decay, which enables us to predict the time variation of weak radioactivity in response to an oscillating axion dark matter background. As an application, we recast old datasets, from the weak nuclear decays of ${}^{40}\mathrm{K}$ and ${}^{137}\mathrm{Cs}$ taken at the underground Gran Sasso Laboratory, in order to set constraints on the axion decay constant, specifically in the axion mass range from few ${10}^{-23}$ up to ${10}^{-19}\mathrm{eV}$. We finally propose a new measurement at the Gran Sasso Laboratory, based on the weak nuclear decay of ${}^{40}\mathrm{K}$ via electron capture, in order to explore even shorter timescales, thus reaching sensitivities to axion masses up to ${10}^{-9}\mathrm{eV}$.

It has recently been suggested that tuning toward the boundary of the positivity domain of the scalar potential may explain the separation between the electroweak scale and the unification scale in a grand unified theory. Here, we explore the possibility that the same type of tuning might account for the generation of the electroweak scale from a much lighter dynamically generated scale in a dark sector. We present a model that realizes this idea and provides a proof of principle that the same dark sector can include a viable dark matter candidate.

The first determination of doubly charmed isospin-0 coupled-channel $D{D}^{*}-D^{*}{D}^{*}$ scattering amplitudes from lattice quantum chromodynamics (QCD) is presented. The finite-volume spectrum is computed for three lattice volumes with a light-quark mass corresponding to $m_{\pi }\approx 391\mathrm{MeV}$ and is used to extract the scattering amplitudes in $J^P=1^{+}$ via the Lüscher quantization condition. By analytically continuing the scattering amplitudes to complex energies, a $T_{cc}$ pole corresponding to a virtual bound state is found below $D{D}^{*}$ threshold. We also find a second pole, $T_{cc}^{\prime }$, corresponding to a resonance pole below the kinematically closed $D^{*}{D}^{*}$ channel, to which it has a strong coupling. A nonzero coupling is robustly found between the $S$-wave $D{D}^{*}$ and $D^{*}{D}^{*}$ channels producing a clear cusp in the $D{D}^{*}$ amplitude at the $D^{*}{D}^{*}$ threshold energy. This suggests that the experimental $T_{cc}^{\prime }$ should be observable in $D{D}^{*}$ and $D^{*}{D}^{*}$ final states at ongoing experiments.

We study the semi-inclusive hadroproduction of doubly bottomed tetraquarks ($X_{b\overline{b}q\overline{q}}$) as well as fully bottomed ones ($T_{4b}$), to which we collectively refer as “bottomoniumlike” states. We rely upon the variable-flavor number-scheme fragmentation at leading power, where a single parton perturbatively splits into the corresponding Fock state, which then hadronizes into the color-neutral, observed tetraquark. To this end, we build new sets of dglap/hf-nrevo consistent, hadron-structure oriented collinear fragmentation functions, which we name TQHL1.1 and TQ4Q1.1 parametrizations. They extend and supersede the corresponding 1.0 versions recently derived in previous works. The first family describes the fragmentation of doubly heavy tetraquarks and is based on an improved version of the Suzuki model for the heavy-quark channel. The second family depicts the fragmentation of fully heavy tetraquarks and embodies initial-scale inputs for gluon and heavy-quark channels, both of them calculated by the hands of potential nonrelativistic QCD. As a phenomenological application, we provide novel predictions for tetraquark-plus-jet high-energy distributions, computed within the $\mathrm{NLL}/{\mathrm{NLO}}^{+}$ hybrid factorization from (sym)jethad, at 14 and 100 TeV FCC.

This study reexamines the spectroscopic parameters of light-flavor diquarks within the framework of quantum chromodynamics sum rules (QCDSR) using the inverse matrix method. Conventional QCDSR analyses are based on assumptions such as quark-hadron duality and continuum models, which introduce a degree of systematic uncertainty. The inverse matrix method circumvents these assumptions by reformulating the problem as an inverse integral equation and expanding the unknown spectral density using orthogonal Laguerre polynomials. This method allows for a direct determination of spectral densities, thereby enhancing the precision of predictions regarding resonance masses and decay constants. By employing this methodology with regard to light-flavor diquarks ($sq$ and $ud$), it is possible to extract the associated masses and decay constants. The results indicate that the masses of diquarks with quantum numbers $J^P=0^{+}$ and $J^P=0^{-}$ are nearly degenerate. We compare our results regarding masses and decay constants with those of other theoretical predictions, which could prove a useful complementary tool in interpretation. Our results are consistent with those in the literature and can be shown as evidence for the consistency of the method. The results achieved in this study highlight the potential of the inverse matrix method as a robust tool for exploring nonperturbative QCD phenomena and elucidating the internal structure of exotic hadronic systems.

We extend our nonperturbative essentially relativistic approach, elaborated previously, to perform an approximate estimation of the size of ${\pi }^0$ meson. We present detailed argumentation for choosing the mass mean square radius (mass MSR) for this purpose. Its value calculated in our approach, using three model quark-antiquark wave functions in pion, is $(0.5–0.53)\mathrm{fm}$. The neutral-pion electromagnetic form factor is zero in accordance with the charge-conjugation symmetry. We demonstrate ambiguities encountered when using standard definitions of mechanical MSR for the size. We discuss MSRs obtained in various approaches and their comparison with each other and with our results.

Understanding nuclear effects is essential for improving the sensitivity of neutrino oscillation measurements. Validating nuclear models solely through neutrino scattering data is challenging due to limited statistics and the broad energy spectrum of neutrinos. In contrast, electron scattering experiments provide abundant high-precision data with various monochromatic energies and angles. Since both neutrinos and electrons interact via electroweak interactions, the same nuclear models can be applied to simulate both interactions. Thus, high-precision electron scattering data is essential for validating the nuclear models used in neutrino experiments. To enable this, the author has introduced a new electron scattering framework in the neut neutrino event generator, covering two interaction modes: quasielastic (QE) and single pion production. neut predictions of QE agree well with numerical calculations, supporting the validity of this implementation. From comparisons with neut predictions and inclusive electron scattering data, the momentum-dependent removal energy correction is derived, addressing effects beyond the plane wave impulse approximation. This correction is applied to neutrino interactions, observing significant changes in charged lepton kinematics. Notably, the reconstructed neutrino energy distribution shows a peak shift of approximately 20–30 MeV, which is crucial for accurately measuring neutrino oscillation parameters.

Superfluid ${}^4\mathrm{He}$ is an ideal candidate for the direct detection of light dark matter via nuclear recoils thanks to its low nuclear mass and the possibility to reach a low-detection-energy threshold by exploiting the generated quasiparticles. The design of future detectors based on this target, such as the DELight experiment, requires a proper understanding of the formation and partitioning of the signal for different energy depositions from various sources. This work presents an overview of the physical processes involved in the energy deposition of recoiling electrons and ions, and it describes a Monte Carlo approach to the partitioning of the signal into different channels. Despite an overall good agreement with existing literature, differences in the region of interest for light dark matter searches below 200 eV are observed.