We study a class of leptogenesis scenarios with decay or scattering being the source of lepton asymmetry, which can not only give rise to the observed baryon asymmetry in the Universe but also can leave behind a large remnant of neutrino asymmetry. Such large neutrino asymmetry can not only be probed at future cosmic microwave background experiments but is also motivating due to its possible role in solving the recently reported anomalies in ${}^4\mathrm{He}$ measurements. Additionally, such large neutrino asymmetry also offers the possibility of cogenesis if dark matter is in the form of a sterile neutrino resonantly produced in the early Universe via Shi-Fuller mechanism. Considering $1\to 2$, $1\to 3$, as well as $2\to 2$ processes to be responsible for generating the asymmetries, we show that only TeV scale leptogenesis preferably of $1\to N(N\ge 3)$ type can generate the required lepton asymmetry around sphaleron temperature while also generating a large neutrino asymmetry $\sim \mathcal{O}({10}^{-2})$ by the epoch of the big bang nucleosynthesis. While such low scale leptogenesis can have tantalizing detection prospects at laboratory experiments, the indication of a large neutrino asymmetry provides a complementary indirect signature.

Two-particle correlations in the proton on the light front are described by a mixed density matrix obtained by tracing over all other, unobserved, degrees of freedom. We quantify genuinely quantum quark azimuthal correlations in terms of the entanglement negativity measure of quantum information theory. While the two-quark state in color space is one of high-entropy and weak-quantum correlation, we find that a standard three-quark model wave function from the literature predicts an azimuthally correlated state of low-entropy and high-entanglement negativity. Low entropy is consistent with expectations for many colors (at fixed ’t Hooft coupling $g^2{N}_{\mathrm{c}}$) but high negativity indicates substantial two-particle quantum correlations at $N_{\mathrm{c}}=3$. We show that suppressing quantum correlations associated with entanglement negativity strongly modifies quark-pair azimuthal moments $⟨{\zeta }^n⟩$, $\zeta =\exp (i({\varphi }_1-{\varphi }_2))$, intrinsic to the proton state. We also describe how to account for the leading $\mathcal{O}(g^2)$ correction to the density matrix from light cone perturbation theory which is due to the presence (or exchange) of a gluon in the proton. This correction increases the entropy and reduces the negativity of the density matrix for quark-pair azimuthal correlations. Hence, the entanglement negativity measure may provide novel insight into the structure of the proton state of QCD.

A new, more precise measurement of the $\mathrm{\Lambda }$ hyperon lifetime is performed using a large data sample of Pb–Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$ with ALICE. The $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ hyperons are reconstructed at midrapidity using their two-body weak decay channel $\mathrm{\Lambda }\to \mathrm{p}+{\pi }^{-}$ and $\overline{\mathrm{\Lambda }}\to \overline{\mathrm{p}}+{\pi }^{+}$. The measured value of the $\mathrm{\Lambda }$ lifetime is ${\tau }_{\mathrm{\Lambda }}=[261.07\pm 0.37\text{(stat.)}\pm 0.72\text{(syst.)}]\mathrm{ps}$. The relative difference between the lifetime of $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$, which represents an important test of $CPT$ invariance in the strangeness sector, is also measured. The obtained value $({\tau }_{\mathrm{\Lambda }}-{\tau }_{\overline{\mathrm{\Lambda }}})/{\tau }_{\mathrm{\Lambda }}=0.0013\pm 0.0028(\mathrm{stat}.)\pm 0.0021(\mathrm{syst}.)$ is consistent with zero within the uncertainties. Both measurements of the $\mathrm{\Lambda }$ hyperon lifetime and of the relative difference between ${\tau }_{\mathrm{\Lambda }}$ and ${\tau }_{\overline{\mathrm{\Lambda }}}$ are in agreement with the corresponding world averages of the Particle Data Group and about a factor of three more precise.

We prove several universal properties of charge transport in generic conformal field theories holographic to nonminimal extensions of four-dimensional Einstein-Maxwell theory with exact electromagnetic duality invariance. First, we explicitly verify that the conductivity of these theories at zero momentum is a universal frequency-independent constant. Then, we derive the analytical expressions for the conductivities at nonzero momentum in any holographic duality-invariant theory for large frequencies and in the limit of small frequencies and momenta. Next, in the absence of terms that couple covariant derivatives of the curvature to gauge field strengths, two universal features are proven. On the one hand, it is shown that for a general-relativity neutral black-hole background the conductivities at any frequency and momentum are independent of the choice of duality-invariant theory, thus coinciding with those in the Einstein-Maxwell case. On the other hand, if higher-curvature terms affect the gravitational background, the conductivities get modified, but the contributions from nonminimal couplings of the gauge field to gravity are subleading. We illustrate this feature with an example.

We consider a general unitary scalar conformal field theory with a linear defect in $D=4-\epsilon$ and a surface defect in $D=6-\epsilon$. Using holography and the Hamilton-Jacobi formalism, we show that the $\beta$ functions controlling the defect renormalization group (RG) flow are the gradient of the entropy function. This allows the proof that the relevant $C$-functions decrease monotonically along the RG flow. We provide evidence that this property also holds in the full quantum theory for general scalar field theories. An obstruction to the gradient property seems to appear at two-loop order when fermions are added.

We introduce the anarchic axion, a class of axion models which solves the strong $CP$ problem within current nEDM constraints with a lighter than usual QCD axion, thus populating new parameter space that ongoing and future experiments target. The anarchic axion is driven light by a soft breaking of the Peccei-Quinn symmetry, which also predicts a residual neutron electric dipole moment. We introduce a novel measure to quantify the tuning required for large deviations from the usual QCD axion band. In addition to motivating searches for unusually light axions, this work establishes a new target for axion effective field theory.

In a previous work [Eur. Phys. J. C 80, 1117 (2020)] about the $T\overline{T}$ deformed ${\mathrm{CFT}}_2$, from the consistency requirement of the entanglement entropy, we found that, in addition to the usual spacelike entanglement entropy, a timelike entanglement entropy must be introduced and treated equally. Motivated by the recent explicit constructions of the timelike entanglement entropy and its bulk dual, we provide a comprehensive analysis of the timelike and spacelike entanglement entropies in the $T\overline{T}$ deformed finite size system and finite temperature system. The results confirm our prediction that in the finite size system only the timelike entanglement entropy receives a correction, while in the finite temperature system only the usual spacelike entanglement entropy gets a correction. These findings affirm the necessity of a complete measure including both spacelike and timelike entanglement entropies.

In this work we consider the observational properties of compact boson stars with self-interactions orbited by isotropically emitting (hot-spot) sources and optically thin accretion disks. We consider two families of boson stars supported by quartic and sixth-order self-interaction potentials, and choose three samples of each of them in growing compactness; only those with large enough compactness are capable to hold light rings, namely, null bound orbits. For the hot spots, using inclination angles $\theta =\{20°,50°,80°\}$ we find a secondary track plunge-through image of photons crossing the interior of the boson star, which can be further decomposed into additional images if the star is compact enough. For accretion disks we find that the latter class of stars actually shows a sequence of additional secondary images in agreement with the hot-spot analysis, a feature absent in typical black hole space-times. Furthermore, we also find a shadowlike central brightness depression for some of these stars in both axial observations and at the inclination angles above. We discuss our findings in relation to the capability of boson stars to effectively act as black hole mimickers in their optical appearances as well as potential observational discriminators.

In this work we present several characteristic examples of theories of gravity and particle physics scenarios that may yield an observable energy spectrum of stochastic primordial gravitational waves, compatible with the 2023 NANOGrav observations. The resulting theories yield a flat or a peaklike energy spectrum, and we further seek the conditions which if hold true, the energy spectrum can be compatible with the recent NANOGrav stochastic gravitational wave detection. As we show, in most cases a blue tilted spectrum combined with a relatively low reheating temperature is needed, the scale of which is determined by whether the radiation domination era is ordinary or it is an abnormal radiation domination era. One intriguing Higgs-axion model, which predicts short slow-roll eras for the axion field at the post-electroweak breaking epoch, which eventually change the total equation of state parameter at the reheating era, can explain the NANOGrav signal, if a blue tilted tensor spectral index inflationary era precedes the reheating era, and a reheating temperature of the order $\mathcal{O}(400)\mathrm{GeV}$. This specific model produces an energy spectrum of primordial gravitational waves with a characteristic peak that is detectable from both the NANOGrav and future LISA experiment, but not from the future Einstein telescope.

We continue to study the properties of the light pseudoscalar nonet within the combined framework of Nambu–Jona-Lasinio model and $1/N_c$ expansion, assuming that current quark masses count of order $\mathcal{O}(1/N_c)$. The masses, mixing angles and decay constants of the ${\pi }^0$, $\eta$ and ${\eta }^{\prime }$ are calculated. The role of the $U(1{)}_A$ anomaly is emphasized. It is shown that the gluon anomaly suppresses the leading order effects that might otherwise be substantial for the $\eta \to 3\pi$ amplitude. A detailed comparison with the known results of $1/N_c$ chiral perturbation theory is made.

A data sample containing top quark pairs ($t\overline{t}$) produced in association with a Lorentz-boosted $Z$ or Higgs boson is used to search for signs of new physics using effective field theory. The data correspond to an integrated luminosity of $138{\mathrm{fb}}^{-1}$ of proton-proton collisions produced at a center-of-mass energy of 13 TeV at the LHC and collected by the CMS experiment. Selected events contain a single lepton and hadronic jets, including two identified with the decay of bottom quarks, plus an additional large-radius jet with high transverse momentum identified as a $Z$ or Higgs boson decaying to a bottom quark pair. Machine learning techniques are employed to discriminate between $t\overline{t}Z$ or $t\overline{t}H$ events and events from background processes, which are dominated by $t\overline{t}+\text{jets}$ production. No indications of new physics are observed. The signal strengths of boosted $t\overline{t}Z$ and $t\overline{t}H$ production are measured, and upper limits are placed on the $t\overline{t}Z$ and $t\overline{t}H$ differential cross sections as functions of the $Z$ or Higgs boson transverse momentum. The effects of new physics are probed using a framework in which the standard model is considered to be the low-energy effective field theory of a higher energy scale theory. Eight possible dimension-six operators are added to the standard model Lagrangian, and their corresponding coefficients are constrained via fits to the data.

Several hairy black hole solutions are known to violate the original version of the celebrated no-hair conjecture. This prompted the development of a new theorem that establishes a universal lower bound on the extension of hairs outside any four-dimensional black hole solutions of general relativity. Our work presents a novel generalization of this “no-short hair” theorem, which notably does not use gravitational field equations and is valid for arbitrary spacetime dimensions ($D\ge 4$). Consequently, irrespective of the underlying theory of gravity, the “hairosphere” must extend to the innermost light ring of the black hole spacetime. Various possible observational implications of this intriguing theorem are discussed, and other useful consequences are explored.

The Schwinger process in strong electric fields creates particles and antiparticles that are entangled. The entropy of entanglement between particles and antiparticles has been found to be equal to the statistical Gibbs entropy of the produced system. Here we study the effect of quantum interference in sequences of electric pulses, and show that quantum interference suppresses the entanglement entropy of the created quantum state. This is potentially relevant to quantum-enhanced classical communications. Our results can be extended to a wide variety of two-level quantum systems.

We derive a factorization theorem for the structure-dependent QED effects in the weak exclusive process $B^{-}\to {\mu }^{-}{\overline{\nu }}_{\mu }$, i.e., effects probing the internal structure of the $B$ meson. The derivation requires a careful treatment of end-point-divergent convolutions common to subleading-power factorization formulas. We find that the decay amplitude is sensitive to two- and three-particle light-cone distribution amplitudes of the $B$ meson as well as to a new hadronic quantity $F(\mu ,\mathrm{\Lambda })$, which generalizes the notion of the $B$-meson decay constant in the presence of QED effects. This is one of the first derivations of a subleading-power factorization theorem in which the soft functions are nonperturbative hadronic matrix elements.

Shibata and Sasaki [Phys. Rev. D 60, 084002 (1999)] introduced the so-called compaction function. Since then, it has been empirically established that the maximum value of this function (or its volume-averaged counterpart) in the long-wavelength solutions gives a very robust threshold of primordial black hole formation. In this paper, we show that in spite of initial intention, the Shibata-Sasaki compaction function cannot be interpreted as the ratio of the mass excess to the areal radius in the constant-mean-curvature slice of their choice but coincides with that in the comoving slice up to a constant factor depending on the equation of state. We also discuss the gauge (in)dependence of the legitimate compaction function, i.e., the ratio of the mass excess to the areal radius, in the long-wavelength solutions.

Gravitational wave (GW) sources at cosmological distances can be used to probe the expansion rate of the Universe. GWs directly provide a distance estimation of the source but no direct information on its redshift. The optimal scenario to obtain a redshift is through the direct identification of an electromagnetic (EM) counterpart and its host galaxy. With almost 100 GW sources detected without EM counterparts (dark sirens), it is becoming crucial to have statistical techniques able to perform cosmological studies in the absence of EM emission. Currently, only two techniques for dark sirens are used on GW observations; the spectral siren method, which is based on the source-frame mass distribution to estimate conjointly cosmology and the source’s merger rate, and the galaxy survey method, which uses galaxy surveys to assign a probabilistic redshift to the source while fitting cosmology. It has been recognized, however, that these two methods are two sides of the same coin. In this paper, we present a novel approach to unify these two methods. We apply this approach to several observed GW events using the glade+ galaxy catalog discussing limiting cases. We provide estimates of the Hubble constant, modified gravity propagation effects, and population properties for binary black holes. We also estimate the binary black hole merger rate per galaxy to be ${10}^{-6}–{10}^{-5}{\mathrm{yr}}^{-1}$ depending on the galaxy catalog hypotheses.

We show the absence of an instability of homogeneous (chiral) condensates against spatially inhomogeneous perturbations for various ($2+1$)-dimensional four-fermion and Yukawa models. All models are studied at nonzero baryon chemical potential, while some of them are also subjected to chiral and isospin chemical potential. The considered theories contain up to 16 Lorentz-(pseudo)scalar fermionic interaction channels. We prove the stability of homogeneous condensates by analyzing the bosonic two-point function, which can be expressed in a purely analytical form at zero temperature. Our analysis is presented in a general manner for all of the different discussed models. We argue that the absence of an inhomogeneous chiral phase (where the chiral condensate is spatially nonuniform) follows from this lack of instability. Furthermore, the existence of a moat regime, where the bosonic wave-function renormalization is negative, in these models is ruled out.

The nature of neutrino masses and the matter-antimatter asymmetry of our universe are two of the most important open problems in particle physics today and are notoriously difficult to test with current technology. Dirac neutrinos offer a solution through a leptogenesis mechanism that hinges on the smallness of neutrino masses and resultant nonthermalization of the right-handed neutrino partners in the early universe. We thoroughly explore possible realizations of this Dirac leptogenesis idea, revealing new windows for highly efficient asymmetry generation. In many of them, the number of relativistic degrees of freedom, $N_{\mathrm{eff}}$, is severely enhanced compared to standard cosmology and offers a novel handle to constrain Dirac leptogenesis with upcoming measurements of the cosmic microwave background. Realizations involving leptoquarks even allow for low-scale postsphaleron baryogenesis and predict proton decay. These novel aspects render Dirac leptogenesis surprisingly testable.

Light sterile neutrinos with a mass of $\sim 1\mathrm{eV}$ continue to be interesting due to multiple hints from terrestrial experiments. This simple hypothesis suffers from strong astrophysical constraints, in particular from the early Universe as well as solar neutrinos. We develop a cosmologically viable proposal consistent with the terrestrial hints, as well as solar constraints, by sourcing the sterile neutrino’s mass from ordinary matter via an ultralight scalar $\varphi$ which can also be the dark matter. In this scenario, the experimentally implied $\sim 1\mathrm{eV}$ sterile neutrino mass is a local value and changes throughout spacetime.