The gravitational-wave energy-density spectra from cosmological first-order phase transitions crucially depend on the terminal wall velocity of asymptotic bubble expansion when the driving force from the effective potential difference is gradually balanced by the backreaction force from the thermal plasma. Much attention has previously focused on the backreaction force acting on the bubble wall alone but overlooked the backreaction forces on the sound shell and shock-wave front, if any, which have been both numerically and analytically accomplished in our previous studies but only for a bag equation of state. In this paper, we will generalize the backreaction force on bubble expansion beyond the simple bag model.

Generative artificial intelligence is a fast-growing area of research offering various avenues for exploration in high-energy nuclear physics. In this work, we explore the use of generative models for simulating electron-proton collisions relevant to experiments like the Continuous Electron Beam Accelerator Facility and the future Electron-Ion Collider (EIC). These experiments play a critical role in advancing our understanding of nucleons and nuclei in terms of quark and gluon degrees of freedom. The use of generative models for simulating collider events faces several challenges such as the sparsity of the data, the presence of global or eventwide constraints, and steeply falling particle distributions. In this work, we focus on the implementation of diffusion models for the simulation of electron-proton scattering events at EIC energies. Our results demonstrate that diffusion models can reproduce relevant observables such as momentum distributions and correlations of particles, momentum sum rules, and the leading electron kinematics, all of which are of particular interest in electron-proton collisions. Although the sampling process is relatively slow compared to other machine-learning architectures, we find diffusion models can generate high-quality samples. We foresee various applications of our work including inference for nuclear structure, interpretable generative machine learning, and searches of physics beyond the Standard Model.

In this paper, we propose a dedicated forward detector, FOREHUNT (FORward Experiment for HUNdred TeV), for 100 TeV FCC-hh for the detection of light long-lived particles (LLP) coming from $B$-meson decay. We calculate the signal acceptance as a function of mass and proper decay length of the LLP for 100 TeV and interpret our result in terms of model parameters for models of dark Higgs scalar and heavy neutral leptons. We also compare the sensitivity with proposed transverse detectors like MATHUSLA, CODEX-b for HL-LHC, and DELIGHT (Detector for long-lived particles at high energy of 100 TeV) for FCC-hh. Our analysis reveals that if the LLP is light ($\lesssim 4.4\mathrm{GeV}$) and has a low proper decay length ($<10\mathrm{m}$), a forward detector like FOREHUNT is the best option to look for the decaying LLP, while DELIGHT is preferable for higher proper decay lengths.

The next-to-minimal supersymmetric Standard Model with triplets is an attractive extension of the Standard Model. It combines the advantages of the next-to-minimal supersymmetric Standard Model and the minimal supersymmetric Standard Model with triplets to give three tiny Majorana neutrinos masses via a type-$\mathrm{I}+\mathrm{II}$ seesaw mechanism. With the on-shell renormalization scheme, we consider the neutrino masses up to one loop approximation. Applying the effective Lagrangian method, we study the transition magnetic moments of Majorana neutrinos and consider the normal hierarchy and inverse hierarchy neutrino mass spectra within the constraints of experimental data on neutrino oscillations. The solar neutrino transition magnetic moment is further deduced, and compared with the XENONnT experiment limit.

Following previous work we further explore the possibility that the chirally broken phase of gauge theories admits an infrared fixed point interpretation. The slope of the $\beta$ function, ${\beta }_{*}^{\prime }$, is found to vanish at the infrared fixed point which has several attractive features such as logarithmic running. We provide a more in-depth analysis of our previous result that the mass anomalous assumes ${\gamma }_{*}=1$ at the fixed point. The results are found to be consistent with $\mathcal{N}=1$ supersymmetric gauge theories. In a second part the specific properties of a dilaton, the (pseudo-) Goldstone, due to spontaneous symmetry breaking are investigated. Dilaton soft theorems indicate that a soft dilaton mass can only originate from an operator of scaling dimension two. In the gauge theory this role is taken on by the $\overline{q}q$-operator. The quantum chromodynamics (QCD) dilaton candidate, the $\sigma =f_0(500)$ meson is investigated and the singlet-octet mixing is found to be relevant. We briefly discuss the dilaton as a candidate for the Higgs boson, which relies on the ratio of dilaton to pion decay constant being close to unity. In QCD this is approximately satisfied but it is remains unclear if this is accidental or whether there is yet to be uncovered principle behind it.

Data on high-$p_T$ hadron production in heavy ion collisions at Feynman $x_F=0$ indicate at universality of the observed nuclear suppression. Our analysis of the production mechanisms demonstrates important role of the color transparency effects which make the survival probability of a quark-antiquark dipole independent of the quark flavor, provided that the hadron wave function is formed outside the medium. The latter condition imposes restrictions on the range of $p_T$, which should be sufficiently high to make the nuclear suppression universal. We also found that the in-medium broadening rate $\widehat{q}$ (frequently called transport coefficient) significantly depends on the quark flavor, diminishing for heavy quarks.

We present a triple point of a new kind for general relativity, at which two gravitational solitons can coexist with a planar black hole in anti–de Sitter space. Working in the context of nonlinear electrodynamics, we obtain simple, sensible spacetimes for which the thermodynamics can be studied in an analytic manner. The spacetimes are charged under the nonlinear electrodynamics leading to an electric charge for black holes and a magnetic flux for solitons. In the grand-canonical ensemble, we show that the phase space of the theory is very rich, containing reentrant phase transitions, as well as triple points, for small values of the coupling controlling the nonlinearity of the electrodynamics Lagrangian.

We study the discovery prospects for a charged Higgs boson via the $bg\to c{H}^{-}\to c\overline{t}b$ process at the Large Hadron Collider (LHC). Focusing on the general two Higgs doublet model (G2HDM) that possesses extra Yukawa couplings, the process is controlled by extra top couplings ${\rho }_{tc}$ and ${\rho }_{tt}$, which can drive electroweak baryogenesis (EWBG) to account for the baryon asymmetry of the Universe (BAU). We propose benchmark points (BPs) and demonstrate that evidence could emerge at 14 TeV LHC and luminosity of $300{\mathrm{fb}}^{-1}$, with discovery potential at $600{\mathrm{fb}}^{-1}$.

In this paper we present a novel method to extract information on hadron-hadron interactions using for the first time femtoscopic data to constrain the low-energy constants of a QCD effective Lagrangian. This method offers a new way to investigate the nonperturbative regime of QCD in sectors where scattering experiments are not feasible, such as the multistrange and charm ones. As an example of its application, we use the very precise ${\mathrm{K}}^{-}\mathrm{\Lambda }$ correlation function data, recently measured in $pp$ collisions at LHC, to constrain the strangeness $S=-2$ meson-baryon interaction. The model obtained delivers new insights on the molecular nature of the $\mathrm{\Xi }(1620)$ and $\mathrm{\Xi }(1690)$ states.

Data analysis of gravitational waves detected by LIGO–Virgo–KAGRA collaboration and future observatories relies on precise modeling of the sources. In order to build, calibrate, and validate current models, we resort to expensive simulations in numerical relativity (NR), the fully-fledged simulation of Einstein’s equations. Since simulation costs and the dimensionality of parameter space are prohibitive to perform a dense coverage, approximate models interpolate among the available simulation data. We put forward the technique of Gaussian process active learning (GPAL), an adaptive, data-driven protocol for parameter space exploration and training of gravitational wave approximants. We evaluate this proposal by studying a computationally inexpensive scenario, in which we calibrate the approximant TEOBResumS using the NR-informed model as a proxy for NR. In this case study, we find that GPAL reduces the computational cost of training by a factor of 4 with respect to uniform or randomly distributed simulations. Moreover, we consider a parallel implementation which reduces computational time, and hybrid strategies which improve precalibrated models. The Gaussian process regression employed in this approach naturally endows the algorithm with notion of model uncertainty. We comment on the implications of this feature for data analysis.

The lightest neutralino (${\tilde{\chi }}_1^0$) is a good dark matter (DM) candidate in the $R$-parity conserving minimal supersymmetric Standard Model. In this work, we consider the light Higgsino-like neutralino as the lightest stable particle, thanks to a rather small Higgsino mass parameter $\mu$. We then estimate the prominent radiative corrections to the neutralino-neutralino-Higgs boson vertices. We show that for Higgsino-like ${\tilde{\chi }}_1^0$, these corrections can significantly influence the spin-independent direct detection cross section, even contributing close to 100% in certain regions of the parameter space. These corrections, therefore, play an important role in deducing constraints on the mass of the Higgsino-like lightest neutralino DM, and thus the $\mu$ parameter.

We propose a novel signal-consistency test applicable to a broad search for gravitational waves emitted by generic binary black hole (BBH) systems. The test generalizes the time domain ${\xi }^2$ signal-consistency test currently utilized by the gstlal pipeline, which quantifies the discrepancy between the expected signal-to-noise ratio time series with the measured one. While the traditional test is restricted to aligned-spin circular orbits and does not account for higher-order modes (HMs), our test does not make any assumption on the nature of the signal. After addressing the mathematical details of the new test, we quantify its advantages in the context of searching for precessing BBHs and/or BBHs with HM content. Our results reveal that, for precessing signals, the new test is optimal and has the potential to reduce the values of the ${\xi }^2$ statistics by up to 2 orders of magnitude when compared to the standard test. However, in the case of signals with HM content, only a modest enhancement is observed. Recognizing the computational burden associated with the new test, we also derive an approximated signal-consistency test. This approximation maintains the same computational cost as the standard test and can be easily implemented in any matched-filtering pipeline with minimal changes, sacrificing only a few percent of accuracy in the low-SNR regime. However, in the high-SNR regime, the approximated signal-consistency test does not bring any improvement as compared to the “standard” one. By introducing our new test and its approximation and understanding their validity and limitation, this work will benefit any matched-filtering pipeline aimed at searching for BBH signals with strong precession and/or HM content.

We show here that highly polarized x-ray synchrotron radiation from young supernova remnants (SNRs) can be modeled within the framework of diffusive shock acceleration (DSA) and nonlinear magnetic turbulence generation. Cosmic ray acceleration by SNR shocks to very high energies requires efficient magnetic turbulence amplification in the shock precursor. As the strong turbulence generated by Bell’s instability far upstream from the viscous subshock convects through the subshock, nonlinear dynamical effects on the large amplitude, compressible fluctuations produce a downstream layer filled with strong anisotropic turbulence with predominantly radial magnetic fields. The synchrotron radiation from shock accelerated electrons in the turbulent downstream layer has a high degree of polarization shown to be consistent with recent observations of young SNRs by the Imaging X-ray Polarimetry Explorer (IXPE) taking into account high-energy electron losses and line-of-sight integration in a spherical remnant. In the case of our model of Tycho’s SNR, the measured x-ray radiation constrains the thickness of the energy containing interval and the amplitude of cosmic ray driven magnetic turbulence, as well as the maximal energy of accelerated protons. The preferential direction of the x-ray polarization depends sensitively on the SNR shock velocity and the ambient density. A fast shock in a region with high enough density is a favorable place to produce tangential polarization of synchrotron radiation, i.e., a dominantly radial magnetic field. A unique feature of our model is the sensitive dependence of the degree and direction of x-ray polarization on the spatial overlap between regions of amplified magnetic turbulence and TeV electron populations. While this overlap occurs on scales orders of magnitude below the resolution of IXPE, its polarization measurement allows testing of turbulent plasma processes on unprecedented scales.

The study of next-to-leading-power (NLP) corrections in soft emissions continues to attract interest both in quantum chromodynamics (QCD) and in quantum electrodynamics (QED). Soft-photon spectra in particular provide a clean case-study for the experimental verification of the Low-Burnett-Kroll (LBK) theorem. In this paper we study the consistency of the LBK theorem in the context of an ambiguity arising from momentum-conservation constraints in the computation of nonradiative amplitudes. We clarify that this ambiguity leads to various possible formulations of the LBK theorem, which are all equivalent up to power-suppressed effects (i.e., beyond the formal accuracy of the LBK theorem). We also propose a new formulation of the LBK theorem with a modified shifted kinematics which facilitates the numerical computation of nonradiative amplitudes with publicly available tools. Furthermore, we present numerical results for soft-photon spectra in the associated production of a muon pair with a photon, both in $e^{+}{e}^{-}$ annihilation and proton-proton collisions.

We analyze the vacuum structure of an eight-dimensional non-Abelian gauge theory with a compactified four-dimensional torus as the extra dimensions. As a nontrivial background configuration of the gauge field of an $SU(n)$ gauge group, we suppose a magnetic flux in two extra dimensions, and continuous Wilson line phases are also involved. We introduce matter fields and calculate the mass spectrum of low-energy modes appearing in a four-dimensional effective theory in an $SU(3)$ model as an explicit example. As expected, potentially tachyonic states in four-dimensional modes appear from extra-dimensional gauge fields that couple to the flux background since the gauge group is simply connected. The Wilson line phases give a nonvanishing contribution to their masses, and we have a low-energy mass spectrum without tachyonic states, given that these phases take an appropriate value. To verify the validity of the values of the Wilson line phases, we examine the one-loop effective potential for these phases and explicitly show the contribution from each type of field present in our model. It is clarified that, although there seems to be no local minimum in the potential for the Wilson line phases in the pure Yang-Mills case, by including matter fields, we could find a vacuum configuration where tachyonic states disappear.

We consider $CP$-violating $Z^{\prime }$ models to account for the anomalies in $b\to s\ell \ell$ decays. Using the updated constraints from lepton flavor universality violating ratios, $b\to s\mu \mu$ $CP$-conserving and $CP$-violating observables, $B_s-{\overline{B}}_s$ mixing and neutrino trident we obtain the favored parameter space of two classes of $Z^{\prime }$ models generating the new physics scenarios with $\mathrm{Re}[C_9^{\mu \text{NP}}]<0$ and $[C_9^{\mu \text{NP}}=-C_{10}^{\mu \text{NP}},C_9^{e\mathrm{NP}}=-C_{10}^{e\mathrm{NP}}]$. We study the predictions of direct $CP$ asymmetry $A_{CP}$ in $B^{+}\to K^{+}\mu \mu$ decays and $CP$ asymmetric angular observables in these models. The favored $1\sigma$ parameter space of $Z^{\prime }$ models generating scenario $\mathrm{Re}[C_9^{\mu \text{NP}}]<0$ allows for an enhancement in the integrated $A_{CP}$ in $q^2=[8,9]{\mathrm{GeV}}^2$ bin up to $\pm 25\%$, while the $[C_9^{\mu \text{NP}}=-C_{10}^{\mu \text{NP}},C_9^{e\mathrm{NP}}=-C_{10}^{e\mathrm{NP}}]$ scenario allows only positive values of $A_{CP}$. However, these $A_{CP}$ values flip sign depending on the choice of $J/\psi$ phase, hence distinguishing these two $Z^{\prime }$ models through a measurement in this bin requires a more reliable determination of the $J/\psi$ phase. The prediction of $A_{CP}$ in the $q^2=[16,17]{\mathrm{GeV}}^2$ bin are promising as they allow for an enhancement only in the positive direction for $[C_9^{\mu \text{NP}}=-C_{10}^{\mu \text{NP}},C_9^{e\mathrm{NP}}=-C_{10}^{e\mathrm{NP}}]$ scenario, irrespective of the choice of strong phase, while both positive and negative values are allowed for the scenario $\mathrm{Re}[C_9^{\mu \text{NP}}]$. We also find that a future more precise measurement of $CP$-asymmetric angular observables $A_8$ and $A_9$ in the low-$q^2$ bins can provide distinguishing signatures of these two $Z^{\prime }$ models and help constrain new physics $CP$-violating phases.

The problem of fermion masses hierarchy in the Standard Model is considered on a toy model of a 10-dimensional space-time with a IIA supergravity type background. The Dirac equation written on this background, after compactification of extra four- and one-dimensional subspaces, gives the spectrum of Fermi fields which profiles in five dimensions and corresponding Higgs generated masses in four dimensions depend on the eigenvalues of Dirac operator on the named compact subspaces. Schwarzschild Euclidean deformation of the supergravity throat with the “apple-shaped” conical singularity permits to leave only three nondivergent angular modes interpreted as three generations of the down-type quarks. The resulting expressions for the quark masses are a geometry version of the Froggatt-Nielsen mechanism.

To properly solve the coincidence problem (${\mathrm{\Omega }}_{\mathrm{DM}}\simeq 5{\mathrm{\Omega }}_{\mathrm{VM}}$) in a model of asymmetric dark matter, one cannot simply relate the number densities of visible and dark matter without also relating their particle masses. Following previous work, we consider a framework where the dark matter is a confined state of a dark QCD gauge group whose confinement scale is dynamically related to the QCD confinement scale by a mechanism utilizing infrared fixed points of the two gauge couplings. In this work we present a new, “zero-coupling infrared fixed point” approach, which allows a larger proportion of models in this framework to generically relate the masses of the visible and dark matter particles. Due to the heavy mass scale required for the new field content, we introduce supersymmetry to the theory. We consider how these models may be incorporated in a full theory of asymmetric dark matter, presenting some example leptogenesis-like models. We also discuss the phenomenology of these models; in particular, there are gravitational wave signals which, while weak, may be measurable at future mHz and $\mathrm{\mu }\mathrm{Hz}$ detectors.

Conversion-driven freeze-out is an appealing mechanism to explain the observed relic density while naturally accommodating the null results from direct and indirect detection due to a very weak dark matter coupling. Interestingly, the scenario predicts long-lived particles decaying into dark matter with lifetimes favorably coinciding with the range that can be resolved at the LHC. However, the small mass splitting between the long-lived particle and dark matter renders the visible decay products soft, thus challenging current search strategies. We consider four different classes of searches covering the entire range of lifetimes: heavy stable charge particles, disappearing tracks, displaced vertices, and missing energy searches. We discuss the applicability of these searches to conversion-driven freeze-out and derive current constraints highlighting their complementarity. For the displaced vertex search, we demonstrate how a slight modification of the current analysis significantly improves its sensitivity to the scenario.