We systematically study the allowed parameter space for the flavor composition of astrophysical neutrinos measured at Earth, including beyond the Standard Model theories at production, during propagation, and at detection. One motivation is to illustrate the discrimination power of the next-generation neutrino telescopes such as IceCube-Gen2. We identify several examples that lead to potential deviations from the standard neutrino mixing expectation such as significant sterile neutrino production at the source, effective operators modifying the neutrino propagation at high energies, dark matter interactions in neutrino propagation, or nonstandard interactions in Earth matter. IceCube-Gen2 can exclude about 90% of the allowed parameter space in these cases, and hence will allow us to efficiently test and discriminate between models. More detailed information can be obtained from additional observables such as the energy dependence of the effect, fraction of electron antineutrinos at the Glashow resonance, or number of tau neutrino events.

In classical general relativity (GR), an observer falling into an astrophysical black hole is not expected to experience anything dramatic as she crosses the event horizon. However, tentative resolutions to problems in quantum gravity, such as the cosmological constant problem, or the black hole information paradox, invoke significant departures from classicality in the vicinity of the horizon. It was recently pointed out that such near-horizon structures can lead to late-time echoes in the black hole merger gravitational wave signals that are otherwise indistinguishable from GR. We search for observational signatures of these echoes in the gravitational wave data released by the advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), following the three black hole merger events GW150914, GW151226, and LVT151012. In particular, we look for repeating damped echoes with time delays of $8M\log M$ ($+\text{spin}$ corrections, in Planck units), corresponding to Planck-scale departures from GR near their respective horizons. Accounting for the “look elsewhere” effect due to uncertainty in the echo template, we find tentative evidence for Planck-scale structure near black hole horizons at false detection probability of 1% (corresponding to $2.5\sigma$. significance level). Future observations from interferometric detectors at higher sensitivity, along with more physical echo templates, will be able to confirm (or rule out) this finding, providing possible empirical evidence for alternatives to classical black holes, such as in “firewall” or “fuzzball” paradigms.

In this paper, we use 2-tailed Gaussian probability to assign a significance to a p-value, e.g., $1-\mathrm{p}\text{-value}=68\%$ and 95% correspond to $1\sigma$ and $2\sigma$, respectively.

We extend the effective theory approach to the ideal fluid limit where the polarization of the fluid is nonzero. After describing and motivating the equations of motion [1], we expand them around the hydrostatic limit, obtaining the sound wave and vortex degrees of freedom. We discuss how the presence of polarization affects the stability and causality of the ideal fluid limit.

The smallness of neutrino mass, the strong $CP$ problem, and the existence of dark matter are explained in an economical way. The neutrino mass is generated by the colored version of a radiative seesaw mechanism by using color adjoint mediators. The Majorana mass term of the adjoint fermion, which carries lepton number $U(1{)}_{\mathbb{L}}$, is induced by its spontaneous breaking, resulting in a Majoron which doubles as the quantum chromodynamics axion, thereby solving the strong $CP$ problem. The breaking of $U(1{)}_{\mathbb{L}}$ sets simultaneously the seesaw scale for neutrino mass and the Peccei-Quinn breaking scale. This axion is a good candidate for dark matter as usually assumed.

We consider an anomaly free $U(1{)}^{\prime }$ model with favorable couplings to heavy flavors in the Standard Model (SM), as motivated by $B$-meson anomalies at LHCb. Taking the $U(1{)}^{\prime }$ charge to be $Q^{\prime }=y(L_{\mu }-L_{\tau })+x(B_3-L_3)$, we can explain the $B$-meson anomalies without invoking extra charged fermions or flavor violation beyond the SM. We show that there is a viable parameter space with a small $x$ that is compatible with other meson decays, tau lepton, and neutrino experiments as well as the LHC dimuon searches. We briefly discuss the prospects of discovering the $Z^{\prime }$ gauge boson at the LHC in the proposed model.

We consider a minimal supersymmetric Standard Model scenario in which the only light superparticles are a binolike dark matter candidate and a nearly degenerate slepton. It is notoriously difficult to probe this scenario at the Large Hadron Collider (LHC), because the slepton pair-production process yields a final state with soft leptons and small missing transverse energy. We study this scenario in the region of parameter space where the mass difference between the lightest neutralino and the lightest slepton ($\mathrm{\Delta }m$) is $\lesssim 60\mathrm{GeV}$, focusing on the process in which an additional radiated jet provides a transverse boost to the slepton pair. We then utilize the angular separation of the leptons from each other and from the missing transverse energy, as well as the angular separation between the jet and the missing transverse energy, to distinguish signal from background events. We also use the reconstructed ditau mass, the $\cos {\theta }_{{\ell }_1{\ell }_2}^{*}$ variable, and for larger $\mathrm{\Delta }m$, a lower bound on the lepton $p_T$. These cuts can dramatically improve both signal sensitivity and the signal-to-background ratio, permitting discovery at the LHC with reasonable integrated luminosity over the interesting region of parameter space. Using our search strategy the LHC will be able to exclude $m_{\tilde{\mu }}\approx 200\mathrm{GeV}$ for $\mathrm{\Delta }m\lesssim 60\mathrm{GeV}$ at $1.5–3\sigma$ with $1000{\mathrm{fb}}^{-1}$ of integrated luminosity. Although we focus on a particular model, the results generalize to a variety of scenarios in which the dark matter and a leptonic partner are nearly degenerate in mass, and especially to scenarios featuring a scalar mediator.

New light vectors with dimension-4 couplings to Standard Model states have ${\text{(energy/vector mass)}}^2$-enhanced production rates unless the current they couple to is conserved. These processes allow us to derive new constraints on the couplings of such vectors, that are significantly stronger than the previous literature for a wide variety of models. Examples include vectors with axial couplings to quarks and vectors coupled to currents (such as baryon number) that are only broken by the chiral anomaly. Our new limits arise from a range of processes, including rare $Z$ decays and flavor-changing meson decays, and rule out a number of phenomenologically motivated proposals.

We establish and elucidate the physical meaning of the appearance of an acausal mode in the sigma mesonic channel, found in the previous work by the present authors, when the system approaches the ${\mathrm{Z}}_2$ critical point. The functional renormalization-group method is applied to the two-flavor quark-meson model with varying current quark mass $m_q$ even away from the physical value at which the pion mass is reproduced. We first determine the whole phase structure in the three-dimensional space $(T,\mu ,m_q)$ consisting of temperature $T$, quark chemical potential $\mu$ and $m_q$, with the tricritical point, O(4) and ${\mathrm{Z}}_2$ critical lines being located; they altogether make a winglike shape quite reminiscent of those known in the condensed matters with a tricritical point. We then calculate the spectral functions ${\rho }_{\sigma ,\pi }(\omega ,p)$ in the scalar and pseudoscalar channel around the critical points. We find that the sigma mesonic mode becomes tachyonic with a superluminal velocity at finite momenta before the system reaches the ${\mathrm{Z}}_2$ point from the lower density, even for $m_q$ smaller than the physical value. One of the possible implications of the appearance of such a tachyonic mode at finite momenta is that the assumed equilibrium state with a uniform chiral condensate is unstable toward a state with an inhomogeneous $\sigma$ condensate. No such anomalous behavior is found in the pseudoscalar channel. We find that the $\sigma$-to-$2\sigma$ coupling due to finite $m_q$ plays an essential role for the drastic modification of the spectral function.

The strong decays of the two resonances $\eta (2225)$ and $\varphi (2170)$ are discussed for selected decay channels. The two resonances are considered as the $\mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ bound states in the molecular scenario. The phenomenological hadronic molecular approach is employed for the calculation of respective decay modes using effective Lagrangians. Our results show that the decay modes $\eta (2225)\to K^{*}K$ and $\varphi (2175)\to KK$ dominate over the partial decay widths of $\eta (2275)\to VV(\varphi \varphi ,\omega \omega ,K^{*}{K}^{*})$ and $\varphi (2175)\to VS(\omega \sigma ,K^{*}{K}_0^{*}(800),\varphi f_0(980))$ due to phase space and couplings.

We complete our earlier study of the “direct” part of the cross section and spin asymmetry for the photoproduction process $\gamma N\to hX$ by analyzing the “resolved” contribution, for which the photon couples like a hadron through its parton structure. The incident photon and nucleon are longitudinally polarized and one observes a hadron $h$ at high transverse momentum $p_T$. Soft or collinear gluon emissions generate large logarithmic threshold corrections which we resum to next-to-leading logarithmic order. We compare our results with recent spin asymmetry data by the COMPASS Collaboration, highlighting the role of the fragmentation functions.

We study Siegel modular forms associated with the theta lift of twisted elliptic genera of $K3$ orbifolded with $g^{\prime }$ corresponding to the conjugacy classes of the Mathieu group $M_{24}$. For this purpose we rederive the explicit expressions for all the twisted elliptic genera for all the classes which belong to $M_{23}\subset M_{24}$. We show that the Siegel modular forms satisfy the required properties for them to be generating functions of $1/4$ BPS dyons of type II string theories compactified on $K3\times T^2$ and orbifolded by $g^{\prime }$ which acts as a ${\mathbb{Z}}_N$ automorphism on $K3$ together with a $1/N$ shift on a circle of $T^2$. In particular the inverse of these Siegel modular forms admit a Fourier expansion with integer coefficients together with the right sign as predicted from black hole physics. This observation is in accordance with the conjecture by Sen and extends it to the partition function for dyons for all the 7 CHL compactifications. We construct Siegel modular forms corresponding to twisted elliptic genera whose twining character coincides with the class $2B$ and $3B$ of $M_{24}$ and show that they also satisfy similar properties. Apart from the orbifolds corresponding to the 7 CHL compactifications, the rest of the constructions are purely formal.

There are circular planar null geodesics at $r=3M$ around a Schwarzschild black hole of mass $M$. These geodesics form a photon sphere. Null geodesics of the Schwarzschild space-time which do not form the photon sphere are either escape to null infinity or get captured by the black hole. Thus, from the dynamical point of view, the photon sphere represents a smooth basin boundary that separates the basins of escape and capture of the dynamical system governing the null geodesics. Here we consider a Schwarzschild black hole distorted by an external, static, and axisymmetric quadrupolar gravitational field defined by a quadrupole moment $q$. We study null geodesics around such a black hole and show that the photon sphere does not survive the distortion. For $q\lesssim -0.017001$ it transforms into a fractal basin boundary that indicates chaotic behavior of the null geodesics. We calculate the box-counting fractal dimension of the basin boundary and the related uncertainty exponent, which depend on the value of the quadrupole moment.

We construct a relation between the Aretakis charge of any extreme black hole and the Newman-Penrose charge. This is achieved by constructing a conformal correspondence between extreme black holes and what we call weakly asymptotically flat space-times. Under this correspondence, the Newman-Penrose charge of the weakly asymptotically flat space-time maps onto the Aretakis charge of the extreme black hole. Furthermore, we generalize the conformal isometry displayed by the extreme Reissner-Nordström solution to a novel conformal symmetry that acts within a class of static STU supergravity black holes.

The Chern–Simons term is used in the geometric theory of defects. The equilibrium equations with $\delta$-function source are explicitly solved with respect to the $\mathbb{S}\mathbb{O}(3)$ connection. This solution describes one straight linear disclination and corresponds to the singularity in the connection but not the metric which is the flat Euclidean metric. This is the first example of a disclination described within the geometric theory of defects. The corresponding angular rotation field is computed.

The supersymmetry arises in certain theories of fermions coupled to gauge fields and gravity in a spacetime of 11 dimensions. The dynamical brane background has mainly been studied for the class of purely bosonic solutions only, but recent developments involving a time-dependent brane solution have made it clear that one can get more information by asking what happens on supersymmetric systems. In this paper, we construct an exact supersymmetric solution of a dynamical M-brane background in the 11-dimensional supergravity and investigate supersymmetry breaking, the geometric features near the singularity and the black hole horizon.

The Brown-York quasilocal energy is applied to three cosmological problems which have previously been studied with the Hawking-Hayward quasilocal energy (Newtonian simulations of large scale structure formation, turnaround radius in the present accelerating universe, and lensing by the cosmological constant). It is found that, in an appropriate gauge and to first order in the amplitude of the cosmological perturbations describing local structures, the Hawking-Hayward and the Brown-York quasilocal masses predict the same results.

Ultralight scalars have been predicted in a variety of scenarios and advocated as a possible component of dark matter. These fields can form compact regular structures known as boson stars, or—in the presence of horizons—give rise to nontrivial time-dependent scalar hair and a stationary geometry. Because these fields can be coherent over large spatial extents, their interaction with “regular” matter can lead to very peculiar effects, most notably resonances. Here we study the motion of stars in a background describing black holes surrounded by nonaxially symmetric scalar field profiles. By analyzing the system in a weak-field approach, we find that the presence of a scalar field gives rise to secular effects akin to ones existing in planetary and accretion disks. Particularly, the existence of resonances between the orbiting stars and the scalar field may enable angular momentum exchange between them, providing mechanisms similar to planetary migration. Additionally, these mechanisms may allow floating orbits, which are stable radiating orbits. We also show, in the full relativistic case, that these effects also appear when there is a direct coupling between the scalar field and the stellar matter, which can arise due to the presence of a scalar core in the star or in alternative theories of gravity.

We generalize the derivative expansion (DE) approach to the interaction between almost-flat smooth surfaces, to the case of surfaces which are optimally described in cylindrical coordinates. As in the original form of the DE, the obtained method does not depend on the nature of the interaction. We apply our results to the study of the static, zero-temperature Casimir effect between two cylindrical surfaces, obtaining approximate expressions which are reliable under the assumption that the distance between those surfaces is always much smaller than their local curvature radii. To obtain the zero-point energy, we apply known results about the thermal Casimir effect for a planar geometry. To that effect, we relate the time coordinate in the latter to the angular variable in the cylindrical case, as well as the temperature to the radius of the cylinders. We study the dependence of the applicability of the DE on the kind of interaction, considering the particular cases where Dirichlet or Neumann conditions are applied to a scalar field.

This paper explores the effects of both finite width and interference (with background) in the pair production and decay of extra heavy quarks with charge $2/3$ at the LHC. This dynamics is normally ignored in standard experimental searches and we assess herein the regions of validity of current approaches, also evaluating the performances of a set of current experimental analyses at 8 and 13 TeV for the determination of the excluded regions in the $(M_{\mathrm{VLQ}},{\mathrm{\Gamma }}_{\mathrm{VLQ}})$ plane, with $M_{\mathrm{VLQ}}$ being the mass of the vector-like quark and ${\mathrm{\Gamma }}_{\mathrm{VLQ}}$ its width. Further, we discuss the configurations of masses, widths and couplings where the latter breaks down.

We determine the hyperon vector couplings $f_1(0)$ for ${\mathrm{\Sigma }}^{-}\to n{l}^{-}\overline{{\nu }_l}$ and ${\mathrm{\Xi }}^0\to {\mathrm{\Sigma }}^{+}{l}^{-}\overline{{\nu }_l}$ semileptonic decays in the continuum limit with ($2+1$)-flavors of dynamical domain-wall fermions, using the Iwasaki gauge action at two different lattice spacings of $a=0.114(2)$ and 0.086(2) fm. A theoretical estimation of flavor SU(3)-breaking effect on the vector coupling is required to extract $V_{us}$ from the experimental rate of hyperon beta decays. We obtain the vector couplings $f_1(0)$ for $\mathrm{\Sigma }\to N$ and $\mathrm{\Xi }\to \mathrm{\Sigma }$ beta-decays with an accuracy of less than one percent. We then find that lattice results of $f_1(0)$ combined with the best estimate of $|V_{us}|$ with imposing Cabibbo-Kobayashi-Maskawa (CKM) unitarity are slightly deviated from the experimental result of $|V_{us}{f}_1(0)|$ for the $\mathrm{\Sigma }\to N$ beta-decay. This discrepancy can be attributed to an assumption made in the experimental analysis on $|V_{us}{f}_1(0)|$, where the induced second-class form factor $g_2$ is set to be zero regardless of broken SU(3) symmetry. We report on this matter and then estimate the possible value of $g_2(0)$, which is evaluated from the experimental decay rate with our lattice result of $f_1(0)$ under the first-row CKM-unitarity condition.