Due to the conical singularity along the symmetry axis Taub-NUT spacetimes suffer from a long and problematic history of physical interpretation. In 1969 Misner proposed a nonsingular interpretation taking advantage of the spacetime’s topology and its underlying group-theoretic structure. We extend and refine his method to include a broader family of solutions and completely solve the outstanding issue of a nonsingular extension of the Kerr-NUT–(anti–)de Sitter solutions to Einstein’s equations. Our approach relies on an observation that in 2 dimensional algebra of Killing vector fields there exist two distinguished vector fields that may be used to define $U(1)$-principal bundle structure over the nonsingular spaces of non-null orbits. For all admissible parameters we derive appropriate Killing vector fields and discuss limits to spacetimes with less parameters. The global structure of spacetime, together with nonsingular conformal geometry of the infinities is presented and (possibly also projectively nonsingular) Killing horizons is presented.

In this paper, we study the spin transitions of neutrinos caused by the interaction with a gravitational field. We consider a model with a scalar field (describing screening effects) conformally coupled to matter and neutrinos. The presence of screening effects suppresses the neutrino spin-flip probability as compared with general relativity predictions. Such a result could be used, combined with neutrino astronomy, for testing modified theories of gravity and, in turn, screening effects invoked to bypass the solar system and lab tests. Such an analysis has been also extended to the case of the quintessence field surrounding a black hole. Here we investigate the flavor and spin transitions, showing that also in such a case exists a suppression of the effect compared to general relativity prediction.

We investigate an inflationary model constructed from minimally modified gravity (MMG) theories. We study MMG theory in the form of $f(\mathbf{H})\propto {\mathbf{H}}^{1+p}$ gravity, where $\mathbf{H}$ is the Hamiltonian constraint in Einstein gravity and $p$ is a constant. Inflation is difficult to achieve in this theory of gravity unless an additional scalar field playing the role of the inflaton is introduced in the model. We find that the inflaton with an exponential potential can drive inflation with a graceful exit, different from the case of Einstein gravity. The slow-roll parameter for both the exponential and power-law potentials is inversely proportional to number of $e$-foldings, similar to the case of Einstein gravity. We also find for the scalar perturbation that the curvature perturbation on super-Hubble-radius scales grows rapidly during inflation unless $p\sim 0$. For the tensor modes, the amplitude of the perturbations is constant on large scales up to the lowest order in the slow-roll parameter, and the sound speed of the perturbations can deviate from unity and vary with time depending on the form of $f(\mathbf{H})$.

We highlight shortcomings of the dynamical dark energy (DDE) paradigm. For parametric models with an equation of state, $w(z)=w_0+w_{a}f(z)$, for a given function of redshift $f(z)$, we show that the errors in $w_a$ are sensitive to $f(z)$: if $f(z)$ increases quickly with the redshift $z$, then errors in $w_a$ are smaller, and vice versa. As a result, parametric DDE models suffer from a degree of arbitrariness, and focusing too much on one model runs the risk that DDE may be overlooked. In particular, we show the ubiquitous Chevallier-Polarski-Linder model is one of the least sensitive to DDE. We also comment on “wiggles” in $w(z)$ uncovered in nonparametric reconstructions. Concretely, we isolate the most relevant Fourier modes in the wiggles, model them, and fit them back to the original data to confirm the wiggles at $\lesssim 2\sigma$. We delve into the assumptions going into the reconstruction and argue that the assumed correlations, which clearly influence the wiggles, place strong constraints on field theory models of DDE.

The modeling of fast flavor evolution of neutrinos in dense environments has been traditionally carried out by relying on a two flavor approximation for simplicity. In addition, vacuum mixing has been deemed negligible. For the first time, we highlight that the fast flavor evolution in three flavors is intrinsically different from the one obtained in the two flavor approximation. This is due to the exponential growth of flavor mixing in the $e–\mu$ and $e–\tau$ sectors generated by the vacuum term in the Hamiltonian. As a result, substantially larger flavor mixing is found in three flavors. Our findings highlight that the two flavor approximation is not justified for fast pairwise conversion, even if the angular distributions of nonelectron type neutrinos are initially identical.

Axions and axionlike particles are bosonic quantum fields. They are often assumed to follow classical field equations due to their high degeneracy in the phase space. In this work, we explore the disparity between classical and quantum field treatments in the context of density and velocity fields of axions. Once the initial density and velocity fields are specified, the evolution of the axion fluid is unique in the classical field treatment. However, in the quantum field treatment, there are many quantum states consistent with the given initial density and velocity field. We show that evolutions of the density perturbations for these quantum states are not necessarily identical and, in general, differ from the unique classical evolution. To illustrate the underlying physics, we consider a system of large number of bosons in a one-dimensional box, moving under the gravitational potential of a heavy static point mass. We ignore the self-interactions between the bosons here. Starting with homogeneous number density and zero velocity field, we determine the density perturbations in the linear regime in both quantum and classical field theories. We find that classical and quantum evolutions are identical in the linear regime if only one single-particle state is occupied by all the bosons and the self-interaction is absent. If more than one single-particle states are occupied, the density perturbations in quantum evolutions differ from the classical prediction after a certain time which depends upon the parameters of the system.

Time-delay interferometry (TDI) is a post-processing technique used to reduce laser noise in heterodyne interferometric measurements with unequal armlengths, a situation characteristic of space gravitational detectors such as the Laser Interferometer Space Antenna (LISA). This technique consists in properly time-shifting and linearly combining the interferometric measurements in order to reduce the laser noise by several orders of magnitude and to detect gravitational waves. In this communication, we show that the Doppler shift due to the time evolution of the armlengths leads to an unacceptably large residual noise when using interferometric measurements expressed in units of frequency and standard expressions of the TDI variables. We also present a technique to mitigate this effect by including a scaling of the interferometric measurements in addition to the usual time-shifting operation when constructing the TDI variables. We demonstrate analytically and using numerical simulations that this technique allows one to recover standard laser noise suppression which is necessary to measure gravitational waves.

The IceCube Neutrino Observatory has established the existence of a high-energy all-sky neutrino flux of astrophysical origin. This discovery was made using events interacting within a fiducial region of the detector surrounded by an active veto and with reconstructed energy above 60 TeV, commonly known as the high-energy starting event sample (HESE). We revisit the analysis of the HESE sample with an additional 4.5 years of data, newer glacial ice models, and improved systematics treatment. This paper describes the sample in detail, reports on the latest astrophysical neutrino flux measurements, and presents a source search for astrophysical neutrinos. We give the compatibility of these observations with specific isotropic flux models proposed in the literature as well as generic power-law-like scenarios. Assuming ${\nu }_e:{\nu }_{\mu }:{\nu }_{\tau }=1:1:1$, and an equal flux of neutrinos and antineutrinos, we find that the astrophysical neutrino spectrum is compatible with an unbroken power law, with a preferred spectral index of ${2.87}_{-0.19}^{+0.20}$ for the 68% confidence interval.

The flux of high-energy neutrinos passing through the Earth is attenuated due to their interactions with matter. The interaction rate is determined by the neutrino interaction cross section and affects the flux arriving at the IceCube Neutrino Observatory, a cubic-kilometer neutrino detector embedded in the Antarctic ice sheet. We present a measurement of the neutrino cross section between 60 TeV and 10 PeV using the high-energy starting event (HESE) sample from IceCube with 7.5 years of data. The result is binned in neutrino energy and obtained using both Bayesian and frequentist statistics. We find it compatible with predictions from the Standard Model. While the cross section is expected to be flavor independent above 1 TeV, additional constraints on the measurement are included through updated experimental particle identification (PID) classifiers, proxies for the three neutrino flavors. This is the first such measurement to use a ternary PID observable and the first to account for neutrinos from tau decay.

We develop a low scale left-right symmetric model based on $SU(3{)}_C\times SU(2{)}_L\times SU(2{)}_R\times U(1{)}_{B-L}\times Z_2$ with a simplified Higgs sector consisting of only one bidoublet and one $SU(2{)}_R$ doublet. In this model, the tiny values of light neutrino masses are generated through an inverse-seesaw mechanism. We emphasize that in this setup, the tree-level flavor changing neutral current can be strongly suppressed, consistent with the current experimental constraints. We show that the lightest $CP$-even Higgs boson, which is like the standard model Higgs boson, and the next lightest Higgs boson, $h^{\prime }$, are generated from the neutral components of the bidoublet. We show that the mass of the next lightest Higgs boson can be of an order of a few hundred GeVs. We analyze the detection of $h^{\prime }$ at the Large Hadron Collider (LHC) for a center-of-mass energy $\sqrt{s}=14\mathrm{TeV}$ and integrated luminosity $L_{\mathrm{int}}=300{\mathrm{fb}}^{-1}$ via di-Higgs channel: $h^{\prime }\to hh\to b\overline{b}\gamma \gamma$ and also in the $ZZ$ channel: $h^{\prime }\to ZZ\to 4\ell (\ell =e,\mu )$ at an integrated luminosity $L_{\mathrm{int}}=3000{\mathrm{fb}}^{-1}$. We consider three benchmark points for this analysis with $m_{h^{\prime }}=250\mathrm{GeV}$, 400 GeV, and 600 GeV. We show that promising signals with good statistical significances can be obtained in di-Higgs channel, with $2\gamma +2b$-jets final states.

The minimal gauged $U(1{)}_{L_{\mu }-L_{\tau }}$ model has long been known to be able to explain the tension between the theoretical and experimental values of the muon magnetic moment. It has been explored and tested extensively, pushing the viable parameter space into a very tight corner. Further, embedding the $U(1{)}_{L_{\mu }-L_{\tau }}$ model in a supersymmetric (SUSY) framework has been shown to relax some of these constraints and has recently been shown to explain the electron anomalous magnetic moment as well. In this model, the logarithm of the mass ratio of third to second generation (s)leptons control the non-negligible kinetic mixing and may crucially alter many of the constraints. We confront both the non-SUSY and SUSY versions of this class of models with the CsI(2017), the recently released CENNS10 data from the liquid Argon detector, as well as the updated CsI(2020) data of the COHERENT experiment. We use the recoil energy and timing binned data from CsI(2017) and the energy, time, and pulse shape discriminator binned data from CENNS10 to find estimates for the model parameters in a likelihood maximization test. We also show updated exclusions using all of the above data from the COHERENT Collaboration, as well as projected exclusions from the ongoing Coherent CAPTAIN-Mills experiment. The $(g-2{)}_{\mu }$ favored values of the $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge coupling that are still unconstrained overlap with the estimates from COHERENT data within $1\sigma$. The combined COHERENT data is found to prefer the presence of the $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge boson over the Standard Model at $\sim 1.4\sigma$. The global minima of a chi-square deviation function using CsI(2020) as well as CENNS10 total counts has significant overlap with the $(g-2{)}_{\mu }$ favored parameter space in the context of the SUSY and non-SUSY $L_{\mu }-L_{\tau }$ models with a mediator mass in the 20–100 MeV range.

We consider the effects of colored scalar mediators in decays $c\to u$ invisibles. In particular, in these processes, as invisibles, we consider right-handed fermions. The colored scalar ${\overline{S}}_1\equiv (\overline{3},1,-2/3)$, due to its coupling to weak up-quark singlets and invisible right-handed fermions ($\chi$), is very appealing. Then, we consider ${\tilde{R}}_2\equiv (\overline{3},2,1/6)$, which as a weak doublet can couple to both up- and down-quarks and invisible fermions. We determine branching ratios for $D\to \chi \overline{\chi }$, $D\to \chi \overline{\chi }\gamma$ and $D\to \pi \chi \chi$ for several $\chi$ masses, using most constraining bounds.The $D^0-{\overline{D}}^0$ mixing gives the most robust constraint for ${\overline{S}}_1$ and ${\tilde{R}}_2$ when only one down-like quark couples to invisible fermion. When ${\tilde{R}}_2$ with two nonzero Yukawa couplings is analysed, we find that the bound on $B\to K\cancel{E}$ is very constraining. We calculate for decays mediated by ${\overline{S}}_1$ that branching ratios can be $B(D\to \chi \overline{\chi })<{10}^{-8}$ for $m_{\chi }=0.8\mathrm{GeV}$, $B(D\to \chi \overline{\chi }\gamma )\sim {10}^{-12}$ for massless $\chi$, while $B(D^{+}\to {\pi }^{+}\chi \overline{\chi })$ can reach $\sim {10}^{-8}$ for the low mass of $\chi$. In the second scenario with ${\tilde{R}}_2$, we obtain high suppression of these decay rates. We find that future tau-charm factories and Belle II experiments offer good opportunities to search for such processes. Both ${\overline{S}}_1$ and ${\tilde{R}}_2$ might have masses within LHC reach.

We realize high scale supersymmetry in the mirage mediation. The Higgs sector is extended with the Peccei-Quinn symmetry, and the Higgsino mass term is generated by the Kim-Nilles mechanism. In particular, the Peccei-Quinn symmetry breaking scale naturally lies on the mirage messenger scale due to the mixed modulus-anomaly mediation with the gauge coupling unification. Consequently, the Higgsino mass term is of order the weak scale while the gravitino mass is of PeV order. This hierarchy naturally leads to the correct electroweak symmetry breaking. The Higgsinos are thus in the range accessible at future lepton colliders, while other sparticles are well above the current LHC reach and consistent with the observed Higgs boson. The axino is dominantly produced from the modulus decay and accounts for the correct dark matter abundance.

We present lattice QCD results for masses and magnetic polarizabilities of light and strange pseudoscalar mesons, chiral condensates, decay constants of neutral pion, and neutral kaon in the presence of background magnetic fields with $eB$ ranging up to around $3.35{\mathrm{GeV}}^2$ ($\sim 70M_{\pi }^2$) in the vacuum. The computations were carried out in ($2+1$)-flavor QCD mostly on ${32}^3\times 96$ lattices using the highly improved staggered quark action with $M_{\pi }\approx 220\mathrm{MeV}$ at zero temperature. We find that the masses of neutral pseudoscalar mesons monotonously decrease as the magnetic field strength grows and then saturate at a nonzero value, while there exists a nonmonotonous behavior of charged pion and kaon masses in the magnetic field. We observe a $qB$ scaling of the up and down quark flavor components of neutral pion mass, neutral pion decay constant as well as the quark chiral condensates at $0.05\lesssim eB\lesssim 3.35{\mathrm{GeV}}^2$. We show that the correction to the Gell-Mann-Oakes-Renner relation involving the neutral pion is less than 6% and the correction for the relation involving neutral kaon is less than 30% at $eB\lesssim 3.35{\mathrm{GeV}}^2$. We also derive the Ward-Takahashi identities for QCD in the magnetic field in the continuum formulation including the relation between integrated neutral pseudoscalar meson correlators and chiral condensates.

The recent anomalies in $b\to s{\ell }^{+}{\ell }^{-}$ transitions could originate from some new physics beyond the Standard Model. Either to confirm or to rule out this assumption, more tests of $b\to s{\ell }^{+}{\ell }^{-}$ transition are needed. Polarized ${\mathrm{\Lambda }}_b$ decay to a $\mathrm{\Lambda }$ and a dilepton pair offers a plethora of observables that are suitable to discriminate new physics from the Standard Model. In this paper, we present a full angular analysis of a polarized ${\mathrm{\Lambda }}_b$ decay to a $\mathrm{\Lambda }(\to p\pi ){\ell }^{+}{\ell }^{-}$ final state. The study is performed in a set of the operator where the Standard Model operator basis is supplemented with its chirality flipped counterparts, and new scalar and pseudoscalar operators. The full angular distribution is calculated by retaining the mass of the final state leptons. At the low hadronic recoil, we use the heavy quark effective theory framework to relate the hadronic form factors which lead to simplified expression of the angular observables where short- and long-distance physics factorize. Using the factorized expressions of the observables, we construct a number of test of short- and long-distance physics including null tests of the Standard Model and its chirality flipped counterparts that can be carried out using experimental data.

The nonlocal bosonic theory obtained from integrating out all anticommuting and auxiliary variables in a globally supersymmetric theory is characterized by the Nicolai map. The latter is generated by a coupling flow functional differential operator, which can be canonically constructed when the supersymmetry is realized off shell. Given any scalar superfield theory, we present a universal formula for both the Nicolai map and its inverse in terms of an ordered exponential of the integrated coupling flow operator. We demonstrate that our formula also holds for supersymmetric gauge theories.

Extensive air shower detectors of gamma rays in the sub-PeV energy region provide a new and relatively unexplored window for dark matter searches. Here we derive some implications of the recently published Tibet ${\mathrm{AS}}_{\gamma }$ data for decaying dark matter candidates. The available spectral information is already useful in obtaining competitive constraints, surpassing existing limits above 10 PeV mass for hadronic or massive boson final states. This is particularly true if accounting for a benchmark astrophysical background of Galactic cosmic rays in the (0.1–1) PeV range. By relying on the arrival distribution of the photons, we show that significantly better sensitivity can be attained, comparable or better than IceCube also for most leptonic final states. Full data exploitation requires however further information disclosure.

Various gedanken experiments of quantum gravity phenomenology in search of a complete theory of gravity near the Planck scale indicate a modification of the Heisenberg uncertainty principle to the generalized uncertainty principle (GUP). This modification leads to nontrivial contributions on the Hamiltonian of a nonrelativistic particle moving in an arbitrary potential. In this paper we study the path-integral representation of a particle moving in an arbitrary potential using the most general form of the GUP containing both the linear and quadratic contributions in momentum. First we work out the action of the particle in an arbitrary potential and hence find an upper bound to the velocity of a free particle. This upper bound interestingly imposes restrictions on the relation between the GUP parameters $\alpha$ and $\beta$. Analysis shows that $\beta >4{\alpha }^2$. We then deduce the mathematical expressions of classical action and the quantum fluctuations for both free particle and the harmonic oscillator systems.

The symmetries of asymptotically flat spacetimes in general relativity are given by the Bondi-Metzner-Sachs (BMS) group, though there are proposed generalizations of its symmetry algebra. Associated with each symmetry is a charge and a flux, and the values of these charges and their changes can characterize a spacetime. The charges of the BMS group are relativistic angular momentum and supermomentum (which includes four-momentum); the extensions of the BMS algebra also include generalizations of angular momentum called “super angular momentum.” Several different formalisms have been used to define angular momentum, and they produce nonequivalent expressions for the charge. It was shown recently that these definitions can be summarized in a two-parameter family of angular momenta, which we investigate in this paper. We find that requiring that the angular momentum vanishes in flat spacetime restricts the two parameters to be equal. If we do not require that the angular momentum agrees with a common Hamiltonian definition, then we are left with a one-parameter family of angular momenta that includes the definitions from the several different formalisms. We then also propose a similar two-parameter family of super angular momentum. We examine the effect of the free parameters on the values of the angular momentum and super angular momentum from nonprecessing binary-black-hole mergers. The definitions of angular momentum differ at a high post-Newtonian order for these systems, but only when the system is radiating gravitational waves (not before and after). The different super-angular-momentum definitions occur at lower orders, and there is a difference in the change of super angular momentum even after the gravitational waves pass, which arises because of the gravitational-wave memory effect. We estimate the size of these effects using numerical-relativity surrogate waveforms and find they are small but resolvable.