Several observables sensitive to the fragmentation of $b$ quarks into $b$ hadrons are measured using $36{\mathrm{fb}}^{-1}$ of $\sqrt{s}=13\mathrm{TeV}$ proton-proton collision data collected with the ATLAS detector at the LHC. Jets containing $b$ hadrons are obtained from a sample of dileptonic $t\overline{t}$ events, and the associated set of charged-particle tracks is separated into those from the primary $pp$ interaction vertex and those from the displaced $b$-decay secondary vertex. This division is used to construct observables that characterize the longitudinal and transverse momentum distributions of the $b$ hadron within the jet. The measurements have been corrected for detector effects and provide a test of heavy-quark-fragmentation modeling at the LHC in a system where the top-quark decay products are color connected to the proton beam remnants. The unfolded distributions are compared with the predictions of several modern Monte Carlo parton-shower generators and generator tunes, and a wide range of agreement with the data is observed, with $p$ values varying from $5\times {10}^{-4}$ to 0.98. These measurements complement similar measurements from $e^{+}{e}^{-}$ collider experiments in which the $b$ quarks originate from a color singlet $Z/{\gamma }^{*}$.

The feasibility of an ultralow energy nuclear-recoil measurement in liquid xenon using neutron capture is investigated for a small (subkilogram) liquid xenon detector that is optimized for a high scintillation gain, and a pulsed neutron source. The measurement uses the recoil energies imparted to xenon nuclei during the deexcitation process following neutron capture, where promptly emitted $\gamma$ cascades can provide the nuclei with up to $0.3{\mathrm{keV}}_{\mathrm{nr}}$ of recoil energy due to conservation of momentum. A successful calibration of scintillation photon and ionization electron yields below this energy will contribute to a greater sensitivity for liquid xenon experiments in searches for light weakly interacting massive particles.

A search for events with two displaced vertices from long-lived particle (LLP) pairs using data collected by the ATLAS detector at the LHC is presented. This analysis uses $139{\mathrm{fb}}^{-1}$ of proton-proton collision data at $\sqrt{s}=13\mathrm{TeV}$ recorded in 2015–2018. The search employs techniques for reconstructing vertices of LLPs decaying to jets in the muon spectrometer displaced between 3 and 14 m with respect to the primary interaction vertex. The observed numbers of events are consistent with the expected background and limits for several benchmark signals are determined. For the Higgs boson with a mass of 125 GeV, the paper reports the first exclusion limits for branching fractions into neutral long-lived particles below 0.1%, while branching fractions above 10% are excluded at 95% confidence level for LLP proper lifetimes ranging from 4 cm to 72.4 m. In addition, the paper present the first results for the decay of LLPs into $t\overline{t}$ in the ATLAS muon spectrometer.

In this paper the influence of chiral chemical potential ${\mu }_5$ on the phenomenon of diquark condensation and phase structure of dense quark matter altogether is contemplated in the framework of the effective 2-color and 2-flavor Nambu–Jona-Lasinio model. The nonzero values of baryon ${\mu }_B$, isospin ${\mu }_I$ and chiral isospin ${\mu }_{I5}$ chemical potentials are also taken into account. We show that the duality relations between diquark condensation, charged pion condensation, and chiral symmetry breaking phenomena, found in the case of zero ${\mu }_5$, are also valid for any value of ${\mu }_5\ne 0$. In terms of dualities and the influence on the phase diagram, chiral imbalance ${\mu }_5$ stands alone from other chemical potentials. Indeed, in comparison with other chemical potentials, ${\mu }_5$ has two interesting features. (i) In the region of moderate values of ${\mu }_B$, ${\mu }_I$, and ${\mu }_{I5}$ it manifests itself as a universal catalyst, since it enhances just the phase that is realized in the system at ${\mu }_5=0$. (ii) In the second regime, when several other chemical potentials reach rather large values, one could observe a rather complicated and rich phase structure, and chiral chemical potential ${\mu }_5$ can be a factor that not so much catalyzes as triggers rather peculiar phases.

In this paper, it is proved that the teleparallel energy momentum generalizes that of the Arnowitt-Deser-Misner (ADM) formalism. In doing so, it is shown that the teleparallel 4-momentum can be made to coincide with that of the ADM approach whenever the ADM 4-momentum is applicable. The only assumptions are the time gauge for the teleparallel frame and the well-known restrictions for the coordinate system used in the calculation of the ADM 4-momentum. Then, examples where the ADM formalism fails to give consist results, but the teleparallel approach does not, are given. The advantages of the teleparallel stress-energy tensor (density) over the pseudotensor of Landau-Lifshitz are exhibited. Finally, the difficulties in identifying the gravitational angular-momentum density is discussed; it is shown that the spatial part of the proposed angular-momentum density $M^{ab}$ vanishes when the teleparallel frame satisfies the time-gauge condition.

The role of the wandering null geodesic is studied in a black hole spacetime. Based on the continuity of the solution of the geodesic equation, the wandering null geodesics commonly exist and explain the typical phenomena of the optical observation of event horizons. Moreover, a new concept of “black room” is investigated relating the wandering null geodesic to the black hole shadow more closely.

Null shells are a useful geometric construction to study the propagation of infinitesimally thin concentrations of massless particles or impulsive waves. After recalling the necessary and sufficient conditions obtained in [M. Manzano and M. Mars, Classical Quantum Gravity (2021)] that allow for the matching of two spacetimes with null embedded hypersurfaces as boundaries, we will address the problem of matching across Killing horizons of zero order in the case when the symmetry generators are to be identified. The results are substantially different depending on whether the boundaries are nondegenerate or degenerate, and contain or not fixed points (in particular, in the former case the shells have zero pressure but nonvanishing energy density and energy flux in general). We will present the explicit form of the so-called step function in each situation. We will then concentrate on the case of actual Killing horizons admitting a bifurcation surface, where a complete description of the shell and its energy-momentum tensor can be obtained. We will conclude particularizing to the matching of two spacetimes with spherical, plane, or hyperbolic symmetry without imposing this symmetry on the shell itself.

Particular couplings between a scalar field and the Gauss-Bonnet invariant lead to spontaneous scalarization of black holes. Here, we continue our work on simulating this phenomenon in the context of binary black hole systems. We consider a negative coupling for which the black-hole spin plays a major role in the scalarization process. We find two main phenomena: (i) dynamical descalarization, in which initially scalarized black holes form an unscalarized remnant, and (ii) dynamical scalarization, whereby the late merger of initially unscalarized black holes can cause scalar hair to grow. An important consequence of the latter case is that modifications to the gravitational waveform due to the scalar field may only occur postmerger, as its presence is hidden during the entirety of the inspiral. However, with a sufficiently strong coupling, we find that scalarization can occur before the remnant has even formed. We close with a discussion of observational implications for gravitational-wave tests of general relativity.

The asymptotic structure of gauge theories describing fracton interactions is analyzed. Two sets of asymptotic conditions are proposed. Both encompass all known solutions, lead to finite charges and resolve the problem of the divergent energy coming from the monopole contribution. While the first set leads to the expected fracton symmetry algebra, including a dipole charge, the second set provides a soft infinite-dimensional extension of it. These soft charges provide evidence of a rich infrared structure for fractonlike theories and provide one corner of a possible fracton infrared triangle.

In this work, we study the outcomes related to dimensionless tidal deformability ($\mathrm{\Lambda }$) obtained through a relativistic mean-field (RMF) hadronic model including short-range correlations (SRCs) and dark matter (DM) content [Phys. Rev. D 105, 023008 (2022)]. As a dark particle candidate, we use the lightest neutralino interacting with nucleons through the Higgs boson exchange. In particular, we test the model against the constraints regarding the observation of gravitational waves from the binary neutron star merger event GW170817 provided by the LIGO/Virgo Collaboration (LVC). We show that $\mathrm{\Lambda }$ decreases as the dark particle Fermi momentum ($k_F^{\mathrm{DM}}$) increases. This feature favors the RMF-SRC-DM model used here to satisfy the limits of ${\mathrm{\Lambda }}_{1.4}=190_{-120}^{+390}$ ($\mathrm{\Lambda }$ of a $1.4M_{\odot }$ neutron star), and $\tilde{\mathrm{\Lambda }}=300_{-230}^{+420}$ given by the LVC. We also show that as $k_F^{\mathrm{DM}}$ increases, ${\mathrm{\Lambda }}_1$ and ${\mathrm{\Lambda }}_2$, namely, the tidal deformabilities of the binary system, are also moved in the direction of the GW170817 observational data. Finally, we verify that the inclusion of DM in the system does not destroy the $I$-Love relation (correlation between $\mathrm{\Lambda }$ and the dimensionless moment of inertia, $\overline{I}$). The observational data for ${\overline{I}}_{\star }\equiv \overline{I}(M_{\star })=11.10_{-2.28}^{+3.68}$, with $M_{\star }=1.338M_{\odot }$, is obtained by the RMF-SRC-DM model.

The neutrino interaction length scales with energy, and becomes comparable to Earth’s diameter above 10’s of TeV energies. Over terrestrial distances, the tau’s short lifetime leads to an energetic regenerated tau neutrino flux, ${\nu }_{\tau }\to \tau \to {\nu }_{\tau }$, within the Earth. The next generation of neutrino experiments aim to detect ultrahigh energy neutrinos. Many of them rely on detecting either the regenerated tau neutrino, or a tau decay shower. Both of these signatures can be affected by the polarization of the tau through the energy distribution of the secondary particles produced from the tau’s decay. While taus produced in weak interactions are nearly 100% polarized, it is expected that taus experience some depolarization due to electromagnetic interactions in the Earth. In this paper, for the first time we quantify the depolarization of taus in electromagnetic energy loss. We find that tau depolarization has only small effects on the final energy of tau neutrinos or taus produced by high energy tau neutrinos incident on the Earth. Tau depolarization can be directly implemented in Monte Carlo simulations such as nupyprop and taurunner.

We study the effects of vectorlike leptons on the $W$-boson mass in a model with a vectorlike $U(1{)}^{\prime }$ gauge symmetry. This model provides simultaneous explanations for the recent anomalies in the muon anomalous magnetic moment and the semileptonic decays of $B$ mesons. We find that the recent result of the $W$-boson mass’s precise measurement at CDF can be explained if the charged (neutral) vectorlike lepton is lighter than 250 (80) GeV. The light vectorlike leptons may not be excluded by collider experiments if these decay to a physical mode of the $U(1{)}^{\prime }$-breaking scalar field.

We explore supersymmetric SO(10) models predicting observable proton decay and various topological defects which produce different shapes and strengths of gravitational wave backgrounds depending on the scales of intermediate symmetry breaking and inflation as well. We compare these to their nonsupersymmetric counterparts. By identifying the scales at which gravitational wave signals appear, we would be able to track down a particular breaking chain and discern if it has a supersymmetric origin or not. It would also be useful to observe gravitational waves from more than one source among all possible topological defects and first order phase transitions for a realistic breaking chain. For these purposes, we work out specific examples in which the grand unification and relevant intermediate scales are calculable explicitly. It turns out that examples with gravitational waves from different sources are quite difficult to obtain, and the predicted gravitational wave profiles from domain walls and first order phase transitions obtained in some examples will require detectors in the kHz to MHz region.

In a few years, the COMET experiment at J-PARC and the Mu2e experiment at Fermilab will probe the $\mu -e$ conversion rate in the vicinity of $\mathcal{O}({10}^{-17})$ for an Al target with high experimental sensitivity. Within the framework of the minimal supersymmetric extension of the Standard Model with local $B\text{−}L$ gauge symmetry (B-LSSM), we analyze the lepton flavor violating (LFV) process of $\mu -e$ conversion in nuclei. Considering the constraint of the experimental upper limit of the LFV rare decay $\mu \to e\gamma$, the $\mu -e$ conversion rates in nuclei within the B-LSSM can achieve $\mathcal{O}({10}^{-12})$, which is 5 orders of magnitude larger than the future experimental sensitivity at the Mu2e and COMET experiments and may be detected in the near future.

The detection of kilohertz-band gravitational waves promises discoveries in astrophysics, exotic matter, and cosmology. To improve the kilohertz quantum noise–limited sensitivity of interferometric gravitational-wave detectors, we investigate nondegenerate internal squeezing: optical parametric oscillation inside the signal-recycling cavity with distinct signal-mode and idler-mode frequencies. We use an analytic Hamiltonian model to show that this stable, all-optical technique is tolerant to decoherence from optical detection loss and that it, with its optimal readout scheme, is feasible for broadband sensitivity enhancement.

There exists a unique class of local higher spin gravities with propagating massless fields in $4d$—chiral higher spin gravity. Originally, it was formulated in the light-cone gauge. We construct a covariant form of this theory as a free differential algebra up to the next-to-leading order, i.e., at the level of equations of motion. It also contains the recently discovered covariant forms of the higher spin extensions of self-dual Yang-Mills and self-dual gravity, as well as self-dual Yang-Mills and self-dual gravity themselves. From the mathematical viewpoint the result is equivalent to taking the minimal model (in the sense of $L_{\infty }$-algebras) of the jet-space extension of the BV-BRST formulation of chiral higher spin gravity, thereby, containing also information about (presymplectic AKSZ) action, counterterms, anomalies, etc.

The condensates of cold atoms at zero temperature in the tunable binary Bose-Einstein condensate system are studied with the Rabi transition between atomic hyperfine states where the system can be represented by a coupled two-field model of gapless excitations and gapped excitations. We set up the configuration of the supersonic and subsonic regimes with the acoustic horizon between them in the elongated two-component Bose-Einstein condensates, trying to mimic Hawking radiations, in particular due to the gapped excitations. The simplified steplike sound speed change is adopted for the subsonic-supersonic transition so that the model can be analytically treatable. The effective-energy gap term in the dispersion relation of the gapped excitations introduces the threshold frequency ${\omega }_{\min }$ in the subsonic regime, below which the propagating modes do not exist. Thus, the particle spectrum of the Hawking modes significantly deviates from that of the gapless cases near the threshold frequency due to the modified gray-body factor, which vanishes as the mode frequency is below ${\omega }_{\min }$. The influence from the gapped excitations to the quantum entanglement of the Hawking mode and its partner of the gapless excitations is also studied according to the Peres-Horodecki-Simon (PHS) criterion. It is found that the presence of the gapped excitations will deteriorate the quantumness of the pair modes of the gapless excitations when the frequency of the pair modes in particular is around $\omega \sim {\omega }_{\min }$. On top of that, when the coupling constant between the gapless and gapped excitations becomes large enough, the huge particle density of the gapped excitations in the small $\omega$ regime will significantly disentangle the pair modes of the gapless excitations. The detailed time-dependent PHS criterion will be discussed.

We show that the Kantowski-Sachs model of a Schwarzschild black hole interior can be slightly generalized in order to accommodate spatial metrics of different orientations, and in this formulation the equations of motion admit a variable redefinition that makes the system regular at the singularity. This system will then traverse the singularity in a deterministic way (information will be conserved through it), and evolve into a time-reversed and orientation-flipped Schwarzschild white hole interior.

We propose the generic no-scale inflation inspired from string theory compactifications. We consider the Kähler potentials with an inflaton field $\phi$, as well as one, two, and three Kähler moduli. Also, we consider the renormalizable superpotential of $\phi$ in general. We study the spectral index and tensor-to-scalar ratio in details, and find the viable parameter spaces which are consistent with the Planck and BICEP/Keck experimental data on the cosmic microwave background (CMB). The spectral index is $n_s\simeq 1-2/N\sim 0.965$ for all models, and the tensor-to-scalar ratio $r$ is $r\simeq 12/N^2$, $83/N^4$ and $4/N^2$ for the one, two and three moduli models, respectively. The particular $r$ for two moduli model comes from the contributions of the non-negligible higher order term in potential. In the three moduli model, the scalar potential is similar to the global supersymmetry, but the Kähler potential is different. The E model with $\alpha =1$ and T model with $\alpha =1/3$ can be realized in the one modulus model and the three moduli model, respectively. Interestingly, the models with quadratic and quartic potentials still satisfy the current tight bound on $r$ after embedding into no-scale supergravity.

Using a suite of $N$-body simulations, we study the angular clustering of galaxies, halos, and dark matter in $\mathrm{\Lambda }$ cold dark matter and modified gravity (MG) scenarios. We consider two general categories of such MG models, one is the $f(R)$ gravity, and the other is the normal branch of the Dvali-Gabadadze-Porrati brane world. To measure angular clustering we construct a set of observer-frame light cones and resulting mock sky catalogs. We focus on the area-averaged angular correlation functions $W_J$, and the associated reduced cumulants $S_J\equiv W_J/W_2^{(J-1)}$, and robustly measure them up to the ninth order using counts in cells. We find that $0.15<z<0.3$ is the optimal redshift range to maximize the MG signal in our light cones. Analyzing various scales for the two types of statistics, we identify up to 20% relative departures in MG measurements from general relativity (GR), with varying signal significance. For the case of halos and galaxies, we find that third-order statistics offer the most sensitive probe of the different structure formation scenarios, with both $W_3$ and the reduced skewness $S_3$ reaching from $2\sigma$ to $4\sigma$ significance at angular scales $\theta \sim 0.13°$. The MG clustering of the smooth dark matter field is characterized by even stronger deviations ($\gtrsim 5\sigma$) from GR, albeit at a bit smaller scales of $\theta \sim 0.08°$, where baryonic physics is already important. Finally, we stress that our mock halo and galaxy catalogs are characterized by rather low surface number densities when compared to existing and forthcoming state-of-the-art photometric surveys. This opens up exciting potential for testing GR and MG using angular clustering in future applications, with even higher precision and significance than reported here.