We consider minimal type–I seesaw framework to realize $\mu -\tau$ reflection symmetry in the low-energy neutrino mass matrix, $M_{\nu }$. Considering DUNE experiment, we scrutinize its potential to measure the precision of 2-3 mixing angle, ${\theta }_{23}$ and the Dirac $CP$-phase, $\delta$ for the given symmetry. Later, we examine the precision of these two parameters considering NuFit-3.2 data as one of the important true points. To study the low-energy phenomenology, we further discuss various breaking patterns of such an exact symmetry. Moreover, for each breaking scenario we perform the capability test of DUNE for the determination of ${\theta }_{23}$ and to establish the phenomenon of $CP$ violation considering the true benchmark point arising from the breaking of $\mu -\tau$ reflection symmetry. We also make remarks on the potential of DUNE to rule out maximal $CP$-violation or $CP$-conservation hypothesis at a certain confidence level for different scenarios.

We consider the supersymmetric inverse seesaw mechanism for neutrino mass generation within the context of a low-energy effective theory where supersymmetry is broken geometrically in an extra dimensional theory. It is shown that the effective scale characterizing the resulting compact supersymmetric spectrum can be as low as 500–600 GeV for moderate values of $\tan \beta$. The potentially large neutrino Yukawa couplings, naturally present in inverse seesaw schemes, enhance the Higgs mass and allow the superpartners to be lighter than in compact supersymmetry without neutrino masses. The inverse seesaw structure also implies a novel spectrum profile and couplings, in which the lightest supersymmetric particle can be an admixture of isodoublet and isosinglet sneutrinos. Dedicated collider as well as dark matter studies should take into account such specific features.

We extend the so-called singlet doublet dark matter model, where the dark matter is an admixture of a Standard Model singlet and a pair of electroweak doublet fermions, by a singlet scalar field. The new portal coupling of it with the dark sector not only contributes to the dark matter phenomenology (involving relic density and direct detection limits) but also becomes important for generation of dark matter mass through its vacuum expectation value. While the presence of dark sector fermions affects the stability of the electroweak vacuum adversely, we find this additional singlet is capable of making the electroweak vacuum absolutely stable up to the Planck scale. A combined study of dark matter phenomenology and the Higgs vacuum stability issue reflects that the scalar sector mixing angle can be significantly constrained in this scenario.

We present results for the isovector nucleon form factors measured on a $96^4$ lattice at almost the physical pion mass with a lattice spacing of 0.085 fm in $2+1$ flavor QCD. The configurations are generated with the stout-smeared $O(a)$-improved Wilson quark action and the Iwasaki gauge action at $\beta =1.82$. The pion mass at the simulation point is about 146 MeV. A large spatial volume of $(8.1\mathrm{fm}{)}^3$ allows us to investigate the form factors in the small momentum transfer region. We determine the isovector electric radius and magnetic moment from nucleon electric ($G_E$) and magnetic ($G_M$) form factors as well as the axial-vector coupling $g_A$. We also report on the results of the axial-vector ($F_A$), induced pseudoscalar ($F_P$) and pseudoscalar ($G_P$) form factors in order to verify the axial Ward-Takahashi identity in terms of the nucleon matrix elements, which may be called the generalized Goldberger-Treiman relation.

We show that the diffractive forward production of two quarkonia, especially the ${\chi }_{cJ}$ and ${\eta }_c$ states, in proton-proton or proton-ion collisions can access the Weizsäcker-Williams gluon Wigner distribution of the proton. We use the hybrid factorization approach where the collinear, double gluon PDF is applied for one of the protons and the $k_T$-dependent (Wigner or GTMD) distribution for the other. The production of quarkonia is treated in the NRQCD framework. A particularly concise formula is obtained for double ${\chi }_{J=1}$ production.

We explore conventional meson-hybrid mixing in $J^{PC}=1^{++}$ heavy quarkonium using QCD Laplace sum rules. We calculate the cross-correlator between a heavy conventional meson current and heavy hybrid current within the operator product expansion, including terms proportional to the four- and six-dimensional gluon condensates and the six-dimensional quark condensate. Using experimentally determined hadron masses, we construct models of the $1^{++}$ charmonium and bottomonium mass spectra. These models are used to investigate which resonances couple to both currents and thus exhibit conventional meson-hybrid mixing. In the charmonium sector, we find almost no conventional meson-hybrid mixing in the ${\chi }_{c1}(1P)$, minimal mixing in the $X(3872)$, and significant mixing in both the $X(4140)$ and $X(4274)$. In the bottomonium sector, we find minimal conventional meson-hybrid mixing in the ${\chi }_{b1}(1P)$ and significant mixing in both the ${\chi }_{b1}(2P)$ and ${\chi }_{b1}(3P)$.

Dihadron and isolated direct photon-hadron angular correlations are measured in $p+p$ collisions at $\sqrt{s}=200\mathrm{GeV}$. The correlations are sensitive to nonperturbative initial-state and final-state transverse momenta $k_T$ and $j_T$ in the azimuthal nearly back-to-back region $\mathrm{\Delta }\varphi \sim \pi$. To have sensitivity to small transverse momentum scales, nonperturbative momentum widths of $p_{\mathrm{out}}$, the out-of-plane transverse-momentum component perpendicular to the trigger particle, are measured. In this region, the evolution of $p_{\mathrm{out}}$ can be studied when several different hard scales are measured. These widths are used to investigate possible effects from transverse-momentum-dependent factorization breaking. When accounting for the longitudinal-momentum fraction of the away-side hadron with respect to the near-side trigger particle, the widths are found to increase with the hard scale; this is qualitatively similar to the observed behavior in Drell-Yan and semi-inclusive deep-inelastic scattering interactions, where factorization is predicted to hold. The momentum widths are also studied as a function of center-of-mass energy by comparing to previous measurements at $\sqrt{s}=510\mathrm{GeV}$. The nonperturbative jet widths also appear to increase with $\sqrt{s}$ at a similar $x_T$, which is qualitatively consistent to similar measurements in Drell-Yan interactions. Future detailed global comparisons between measurements of processes where transverse-momentum-dependent factorization is predicted to hold and be broken will provide further insight into the role of color in hadronic interactions.

In the Comment on “Can accretion disk properties observationally distinguish black holes from naked singularities?”, by Bertrand Chauvineau, the author did show that the metric used in Z. Kovács and T. Harko, Phys. Rev. D 82, 124047 (2010), and initially introduced in K. D. Krori and D. R. Bhattacharjee, J. Math. Phys. 23, 637 (1982) and K. K. Nandi, P. M. Alsing, J. C. Evans, and T. B. Nayak, Phys. Rev. D 63, 084027 (2001), does not satisfy the Einstein gravitational field equations with a minimally coupled scalar field. In our reply we would like to point out that this result is actually not new, but it was already published in the literature. Moreover, a rotating solution that generalizes the Kerr metric for a nonminimally coupled scalar field does exist. We briefly discuss the nature of the singularities for the generalized metric, and point out that it can be used as a testing ground to differentiate black holes from naked singularities. Moreover, we mention the existence of some other typing or technical errors existing in the literature.

One points out that a metric used as a General Relativity filled by a massless scalar $\phi$ solution in several studies, and that would have been a generalization of the Janis-Newman-Winicour spherical solution to the rotating case, does not solve the corresponding Einstein equation $R_{ab}={\partial }_a\phi {\partial }_b\phi$. As a consequence, the (conformally related) Krori-Bhattacharjee spacetime is not a vacuum Brans-Dicke solution.

We study the supersymmetry breaking induced by probe anti-D3-branes at the tip of the Klebanov-Strassler throat geometry. Antibranes inside this geometry polarize and can be described by an NS5-brane wrapping an $S^2$. When the number of antibranes is small compared to the background flux a metastable state exists that breaks supersymmetry. We present a manifestly supersymmetric effective model that realizes the polarized metastable state as a solution, spontaneously breaking the supersymmetry. The supersymmetric model relies crucially on the inclusion of Kaluza-Klein (matrix) degrees of freedom on the $S^2$ and two supersymmetric irrelevant deformations of $\mathcal{N}=4$ super-Yang-Mills (SYM), describing a large number of supersymmetric D3-branes in the IR. We explicitly identify the massless Goldstino and compute the spectrum of massive fluctuations around the metastable supersymmetry-breaking minimum, finding a Kaluza-Klein tower with masses warped down from the string scale. Below the Kaluza-Klein scale the massive tower can be integrated out and supersymmetry is realized nonlinearly. We comment on the effect of the Kaluza-Klein modes on the effective description of de Sitter vacua in string theory and inflationary model building.

In this paper, we use the “complexity equals action” (CA) conjecture to discuss the action growth rate in a black hole with multiple Killing horizons for a higher curvature theory of gravity. Based on the Noether charge formalism of Iyer and Wald, a general formalism can be resorting to finding the action growth rate within the Wheeler-DeWitt patch at the late time approximation. Moreover, as an application, we apply this formalism to a $U(1)$ invariance matter fields and utilize our results in two specific cases. Our results are universal and can be considered as the extension of the asymptotic AdS to the arbitrary asymptotic one.

AdS/CFT models have achieved considerable success in describing hadronic properties such as masses and Regge trajectories. Even if the minimal vertex that couples photons to structureless spin-zero fields is used, one still ends up with electromagnetic form factors of hadrons that are in fair to good agreement with experiment. However, contradicting both experiment and naive expectation, this minimal model gives zero for hadronic electric and magnetic polarizabilities. We show here that if effective vertices are used, and axial and vector mesons are allowed to propagate as intermediate states, then the static polarizabilities can in principle be computed from AdS/CFT.

It was recently shown that non-Abelian vortex strings supported in a version of four-dimensional $\mathcal{N}=2$ supersymmetric QCD become critical superstrings. In addition to four translational moduli, non-Abelian strings under consideration have six orientational and size moduli. Together they form a ten-dimensional target space required for a superstring to be critical, namely, the product of the flat four-dimensional space and conifold—a noncompact Calabi-Yau threefold. In this paper we report on further studies of low-lying closed string states that emerge in four dimensions and identify them as hadrons of our four-dimensional $\mathcal{N}=2$ QCD. We use the approach based on little string theory, describing the critical string on the conifold as a noncritical $c=1$ string with the Liouville field and a compact scalar at the self-dual radius. In addition to the massless hypermultiplet found earlier we observe several massive vector multiplets and a massive spin-2 multiplet, all belonging to the long (non-BPS) representations of $\mathcal{N}=2$ supersymmetry in four dimensions. All the above states are interpreted as baryons formed by a closed string with confined monopoles attached. Our construction presents an example of a “reverse holography.”

We use the critical point large $N$ formalism to calculate the critical exponents corresponding to the fermion mass operator and flavor nonsinglet fermion bilinear operator in the universality class of quantum electrodynamics coupled to the Gross-Neveu model for an $SU(N)$ flavor symmetry in $d$ dimensions. The $\epsilon$ expansion of the exponents in $d=4-2\epsilon$ dimensions are in agreement with recent three and four loop perturbative evaluations of both renormalization group functions of these operators. Estimates of the value of the nonsinglet operator exponent in three dimensions are provided.

We find stealth Schwarzschild solutions with a nontrivial profile of the scalar field regular on the horizon in the Einstein gravity coupled to the scalar field with the $k$-essence and/or generalized cubic Galileon terms, which is a subclass of the Horndeski theory breaking the shift symmetry, where the propagation speed of gravitational waves coincides with the speed of light. After deriving sufficient conditions for the shift symmetry breaking theory to allow a general Ricci-flat metric solution with a nontrivial scalar field profile, we focus on the stealth Schwarzschild solution with the scalar field with or without time dependence. For the profile $\varphi ={\varphi }_0(r)$, we explicitly obtain two types of stealth Schwarzschild solutions, one of which is regular on the event horizon. The linear perturbation analysis clarifies that the kinetic term of the scalar mode identically vanishes, indicating that the scalar mode is strongly coupled. The absence of the kinetic term of the scalar mode in the quadratic action would inevitably arise for the stealth Schwarzschild solutions in the theory with a general scalar field profile depending only on the spatial coordinates. On the other hand, for the time-dependent scalar field profile, we clarify that there does not exist a stealth Schwarzschild solution in the shift symmetry breaking theories.

Some modified theories of gravity are known to predict monopolar, in addition to the usual quadrupolar and beyond, gravitational radiation in the form of “breathing” modes. For the same reason that octupole and higher-multipole terms often contribute negligibly to the overall wave strain, monopole terms tend to dominate. We investigate both monopolar and quadrupolar continuous gravitational radiation from neutron stars deformed through internal magnetic stresses. We adopt the parametrized-post-Newtonian formalism to write down equations describing the leading-order stellar properties in a theory-independent way, and derive some exact solutions for stars with mixed poloidal-toroidal magnetic fields. We then turn to the specific case of scalar-tensor theories to demonstrate how observational upper limits on the gravitational-wave luminosity of certain neutron stars may be used to place constraints on modified gravity parameters, most notably the Eddington parameter $\gamma$. For conservative, purely poloidal models with characteristic field strength given by the spindown minimum, upper limits for the Vela pulsar yield $1-\gamma \lesssim 4.2\times {10}^{-3}$. For models containing a strong toroidal field housing $\sim 99\%$ of the internal magnetic energy, we obtain the bound $1-\gamma \lesssim 8.0\times {10}^{-7}$. This latter bound is an order of magnitude tighter than those obtained from current Solar System experiments, though applies to the strong-field regime.

The Bardeen metric is the first spherically symmetric regular black hole solution of Einstein’s equations coupled to nonlinear electrodynamics, which has an additional parameter ($e$) due to nonlinear charge apart from mass ($M$). We find a $d$-dimensional Bardeen-de Sitter black hole and analyze its horizon structure and thermodynamical properties. Interestingly, in each spacetime dimension $d$, there exists a critical mass parameter $\mu ={\mu }_E$, which corresponds to an extremal black hole when Cauchy and event horizons coincide, which for $\mu >{\mu }_E$ describes a nonextremal black hole with two horizons and no black hole for $\mu <{\mu }_E$. We also find that the extremal value ${\mu }_E$ is influenced by the spacetime dimension $d$. Owing to the nonlinear charge corrected metric, the thermodynamic quantities of the black holes also get modified and a Hawking-Page-like phase transition exists. The phase transition is characterized by a divergence of the heat capacity at a critical radius $r_{+}=r_{+}^C$, with the stable (unstable) branch for $C_e>(<)0$. The Hawking evaporation of black holes leads to a thermodynamically stable double-horizon black hole remnant with the vanishing temperature.

We combine model-independent reconstructions of the expansion history from the latest Pantheon supernovae distance modulus compilation and measurements from baryon acoustic oscillation to test some important aspects of the concordance model of cosmology namely the Friedmann-Lemaître-Robertson-Walker (FLRW) metric and flatness of spatial curvature. We then use the reconstructed expansion histories to fit growth measurement from redshift-space distortion and obtain constraints on (${\mathrm{\Omega }}_{\mathrm{m}}$, $\gamma$, ${\sigma }_8$) in a model independent manner. Our results show consistency with a spatially flat FLRW Universe with general relativity to govern the perturbation in the structure formation and the cosmological constant as dark energy. However, we can also see some hints of tension among different observations within the context of the concordance model related to high redshift observations ($z>1$) of the expansion history. This supports earlier findings of [G.-B. Zhao, Nat. Astron. 1, 627 (2017), V. Sahni, A. Shafieloo, and A.  A. Starobinsky, Astrophys. J. 793, L40 (2014)] and highlights the importance of precise measurement of expansion history and growth of structure at high redshifts.

Cosmological observations are used to test for imprints of an ultralight axionlike field (ULA), with a range of potentials $V(\varphi )\propto [1-\cos (\varphi /f){]}^n$ set by the axion-field value $\varphi$ and decay constant $f$. Scalar field dynamics dictate that the field is initially frozen and then begins to oscillate around its minimum when the Hubble parameter drops below some critical value. For $n=1$, once dynamical, the axion energy density dilutes as matter; for $n=2$ it dilutes as radiation and for $n=3$ it dilutes faster than radiation. Both the homogeneous evolution of the ULA and the dynamics of its linear perturbations are included, using an effective fluid approximation generalized from the usual $n=1$ case. ULA models are parametrized by the redshift $z_c$ when the field becomes dynamical, the fractional energy density $f_{z_c}\equiv {\mathrm{\Omega }}_a(z_c)/{\mathrm{\Omega }}_{\mathrm{tot}}(z_c)$ in the axion field at $z_c$, and the effective sound speed $c_s^2$. Using Planck, BAO and JLA data, constraints on $f_{z_c}$ are obtained. ULAs are degenerate with dark energy for all three potentials if $1+z_c\lesssim 10$. When $3\times {10}^4\gtrsim 1+z_c\gtrsim 10$, $f_{z_c}$ is constrained to be $\lesssim 0.004$ for $n=1$ and $f_{z_c}\lesssim 0.02$ for the other two potentials. The constraints then relax with increasing $z_c$. These results have implications for ULAs as a resolution to cosmological tensions, such as discrepant measurements of the Hubble constant, or the EDGES measurement of the global 21 cm signal.

Gravitational waves from inspiraling compact objects provide us with information of the distance scale since we can infer the absolute luminosity of the source from analysis of the wave form, which is known as standard sirens. The first detection of the gravitational wave signal of the binary black hole merger event by Advanced LIGO has opened up the possibility of utilizing standard sirens as cosmological probe. In order to extract information of the distance-redshift relation, we cross-correlate weak lensing, which is an unbiased tracer of matter distribution in the Universe, with the projected number density of gravitational wave sources. For weak lensing, we employ tomography technique to efficiently obtain information of large-scale structures at wide ranges of redshifts. Making use of the cross-correlations along with the autocorrelations, we present forecast of constraints on four cosmological parameters, i.e., Hubble parameter, matter density, the equation of state parameter of dark energy, and the amplitude of matter fluctuation. To fully explore the ability of cross-correlations, which require large overlapping sky coverage, we consider the specific case with the upcoming surveys by Euclid for weak lensing and Einstein Telescope for standard sirens. We show that cosmological parameters can be tightly constrained solely by these auto- and cross-correlations of standard sirens and weak lensing. For example, the $1\text{−}\sigma$ error of Hubble parameter is expected to be $\sigma (H_0)=0.33\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$. Thus, the proposed statistics will be a promising probe into the distance scale.