We study the possibility of probing different texture zero neutrino mass matrices at the long baseline neutrino experiment DUNE, particularly focusing on its sensitivity to the octant of atmospheric mixing angle ${\theta }_{23}$ and leptonic Dirac $CP$ phase ${\delta }_{\mathrm{cp}}$. Assuming a diagonal charged lepton basis and Majorana nature of light neutrinos, we first classify the possible light neutrino mass matrices with one and two texture zeros and then numerically evaluate the parameter space which satisfies the texture zero conditions. Apart from using the latest global fit $3\sigma$ values of neutrino oscillation parameters, we also use the latest bound on the sum of absolute neutrino masses $(\sum _i|m_i|)$ from the Planck mission data and the updated bound on effective neutrino mass $M_{ee}$ from neutrinoless double beta decay $(0\nu \beta \beta )$ experiments to find the allowed Majorana texture zero mass matrices. For the allowed texture zero mass matrices from all these constraints, we then feed the corresponding light neutrino parameter values satisfying the texture zero conditions into the numerical analysis in order to study the capability of DUNE to allow or exclude them once it starts taking data. We find that DUNE will be able to exclude some of these texture zero mass matrices which restrict $({\theta }_{23}\text{−}{\delta }_{\mathrm{cp}})$ to a very specific range of values, depending on the values of the parameters that nature has chosen.

We solve the Faddeev equations for the bound state problem of three particles to study different three-body systems containing open flavor heavy mesons: $\overline{D}NN$, $BNN$, $\overline{D}\overline{D}N$ and $BBN$. We use a coupled-channel formalism considering the $S$-wave spin excitations of the constituent hadrons: ${\overline{D}}^{*}$, $B^{*}$, and $\mathrm{\Delta }$ when deemed relevant. Our study comes motivated by the recent prediction of deeply bound states in different two-body subsystems participating in the aforementioned three-body states. The existence of three-body bound states with open flavor heavy mesons would open the door to exotic nuclei with heavy flavors. Our results point against such possibility.

The electromagnetic probe has proven to be a very efficient way to access the three-dimensional structure of the nucleon, particularly thanks to the exclusive Compton processes. We explore the hard photoproduction of a large invariant mass diphoton in the kinematical regime where the diphoton is nearly forward and its invariant mass is the hard scale enabling to factorize the scattering amplitude in terms of generalized parton distributions. We calculate unpolarized cross sections and the angular asymmetry triggered by a linearly polarized photon beam.

We use the covariant spectator theory with an effective quark-antiquark interaction, containing Lorentz scalar, pseudoscalar, and vector contributions, to calculate the masses and vertex functions of, simultaneously, heavy and heavy-light mesons. We perform least-square fits of the model parameters, including the quark masses, to the meson spectrum and systematically study the sensitivity of the parameters with respect to different sets of fitted data. We investigate the influence of the vector confining interaction by using a continuous parameter controlling its weight. We find that vector contributions to the confining interaction between 0% and about 30% lead to essentially the same agreement with the data. Similarly, the light quark masses are not very tightly constrained. In all cases, the meson mass spectra calculated with our fitted models agree very well with the experimental data. We also calculate the mesons wave functions in a partial wave representation and show how they are related to the meson vertex functions in covariant form.

The de Finetti theorem and its extensions concern the structure of multipartite probability distributions with certain symmetry properties, the paradigmatic original example being permutation symmetry. These theorems assert that such symmetric distributions are well approximated by convex combinations of uncorrelated ones. In this article, we apply de Finetti theorems to quantum gravity theories, such as the Sachdev-Ye-Kitaev (SYK) model or large-$N$ vector and gauge theories. For SYK we put recent studies of information/entanglement dynamics in a general and rigorous basis. For vector and gauge theories, we describe the classicality of the modular Hamiltonian, its modular flows, and the entanglement entropy. These results can be unified through a generic statement about the nature of Schmidt decompositions and decoherence in large-$N$ theories. In the reverse direction, we extend de Finetti theorems in various ways and provide an independent approach to the theorems only based on the large-$N$ properties of the gauge invariant coherence group.

In this work we focus on a novel completion of the well-known Brans-Dicke theory that introduces an interaction between the dark energy and dark matter sectors, known as complete Brans-Dicke (CBD) theory. We obtain viable cosmological accelerating solutions that fit supernovae observations with great precision without any scalar potential $V(\varphi )$. We use these solutions to explore the impact of the CBD theory on the large scale structure by studying the dynamics of its linear perturbations. We observe a growing behavior of the lensing potential ${\mathrm{\Phi }}_{+}$ at late-times, while the growth rate is actually suppressed relatively to $\mathrm{\Lambda }\mathrm{CDM}$, which allows the CBD theory to provide a competitive fit to current RSD measurements of $f{\sigma }_8$. However, we also observe that the theory exhibits a pathological change of sign in the effective gravitational constant concerning the perturbations on subhorizon scales that could pose a challenge to its validity.

We have earlier proposed a fourth order gravity model as a possible explanation for late time cosmic acceleration and for flattened galaxy rotation curves. The model has a free length parameter whose value depends on the scale of the system under study (e.g., the whole Universe, a galaxy, or a compact binary pulsar). In the present work, we investigate the constraints imposed on the free model parameter by PSR $1913+16$ (Hulse-Taylor binary pulsar), PSR $\mathrm{J}1518+4904$, and PSR J0737-3039 data: periastron advance, and emission of gravitational waves and consequent period decay. It is shown that the model is consistent with these observations, provided the length parameter is bounded from above, but is unstable due to the presence of ghost degrees of freedom.

We develop a general framework for the open dynamics of an ensemble of quantum particles subject to spacetime fluctuations about the flat background. An arbitrary number of interacting bosonic and fermionic particles are considered. A systematic approach to the generation of gravitational waves in the quantum domain is presented that recovers known classical limits in terms of the quadrupole radiation formula and backreaction dissipation. Classical gravitational emission and absorption relations are quantized into their quantum field theoretical counterparts in terms of the corresponding operators and quantum ensemble averages. Certain arising consistency issues related to factor ordering have been addressed and resolved. Using the theoretical formulation established here with numerical simulations in the quantum regime, we discuss potential new effects including decoherence through the spontaneous emission of gravitons and collectively amplified radiation of gravitational waves by correlated quantum particles.

The formulation of the laws of Black hole mechanics assumes the stability of black holes under perturbations in accordance with the “cosmic censorship hypothesis” (CCH). CCH prohibits the formation of a naked singularity by a physical process from a regular black hole solution with an event horizon. Earlier studies show that naked singularities can indeed be formed leading to the violation of CCH if a near-extremal black hole is injected with massive charged particles and the backreaction effects are neglected. We investigate the validity of CCH by considering the infall of charged massless particles as well as a charged null shell. We also discuss the issue of the third law of Black hole mechanics in the presence of null charged particles by considering various possibilities.

We disclose a novel phase transition in black hole physics by investigating thermodynamics of charged dilaton black holes in an extended phase space where the charge of the black hole is regarded as a fixed quantity. Along with the usual critical (second-order) as well as the first-order phase transitions in charged black holes, we find that a finite jump in Gibbs free energy is generated by the dilaton-electromagnetic coupling constant $\alpha$ for a certain range of pressure. This novel behavior indicates a small/large black hole zeroth-order phase transition the thermodynamic response function of black hole diverges, e.g., isothermal compressibility. Such zeroth-order transition separates the usual critical point and the standard first-order transition curve. We show that increasing the dilaton parameter ($\alpha$) increases the zeroth-order portion of the transition curve. Additionally, we find that the second-order (critical) phase transition exponents are unaffected by the dilaton parameter; however, the condition of positive critical temperature puts an upper bound on the dilaton parameter ($\alpha <1$).

Conformal loop quantum gravity provides an approach to loop quantization through an underlying conformal structure i.e. conformally equivalent class of metrics. The property that general relativity itself has no conformal invariance is reinstated with a constrained scalar field setting the physical scale. Conformally equivalent metrics have recently been shown to be amenable to loop quantization including matter coupling. It has been suggested that conformal geometry may provide an extended symmetry to allow a reformulated Immirzi parameter necessary for loop quantization to behave like an arbitrary group parameter that requires no further fixing as its present standard form does. Here, we find that this can be naturally realized via conformal frame transformations in scalar-tensor gravity. Such a theory generally incorporates a dynamical scalar gravitational field and reduces to general relativity when the scalar field becomes a pure gauge. In particular, we introduce a conformal Einstein frame in which loop quantization is implemented. We then discuss how different Immirzi parameters under this description may be related by conformal frame transformations and yet share the same quantization having, for example, the same area gaps, modulated by the scalar gravitational field.

We use our previously developed identification of dispersion relations with Hamilton functions on phase space to locally implement the $\kappa$-Poincaré dispersion relation in the momentum spaces at each point of a generic curved spacetime. We use this general construction to build the most general Hamiltonian compatible with spherical symmetry and the Plank-scale-deformed one such that in the local frame it reproduces the $\kappa$-Poincaré dispersion relation. Specializing to Planck-scale-deformed Schwarzschild geometry, we find that the photon sphere around a black hole becomes a thick shell since photons of different energy will orbit the black hole on circular orbits at different altitudes. We also compute the redshift of a photon between different observers at rest, finding that there is a Planck-scale correction to the usual redshift only if the observers detecting the photon have different masses.

We aim to explain in a unified way the experimental data on ultrahigh-energy cosmic rays (UHECRs) and neutrinos, using a single source class and obeying limits on the extragalactic diffuse gamma-ray background. If UHECRs only interact hadronically with gas around their sources, the resulting diffuse cosmic-ray (CR) flux can be matched well to the observed one, providing at the same time large neutrino fluxes. Since the required fraction of heavy nuclei is, however, rather large, the maxima of air showers in the Earth’s atmosphere induced by UHECRs with energies $E\gtrsim 3\times {10}^{18}\mathrm{eV}$ would be too high. Therefore, additional photohadronic interactions of UHECRs close to the accelerator have to be present, in order to modify the nuclear composition of CRs in a relatively narrow energy interval. We thus include both photon and gas backgrounds and combine the resulting CR spectra with the high-energy part of the Galactic CR fluxes predicted by the escape model. As result, we find a good description of experimental data on the total CR flux, the mean shower maximum depth $X_{\max }$ and its width $rms(X_{\max })$ in the whole energy range above $E\simeq {10}^{17}\mathrm{eV}$. The predicted high-energy neutrino flux matches IceCube measurements, while the contribution to the extragalactic diffuse gamma ray background is of order 30%.

In coalescing neutron star (NS) binaries, tidal force can resonantly excite low-frequency ($\lesssim 500\mathrm{Hz}$) oscillation modes in the NS, transferring energy between the orbit and the NS. This resonant tide can induce phase shift in the gravitational waveforms, and potentially provide a new window of studying NS interior using gravitational waves. Previous works have considered tidal excitations of pure g-modes (due to stable stratification of the star) and pure inertial modes (due to Coriolis force), with the rotational effect treated in an approximate manner. However, for realistic NSs, the buoyancy and rotational effects can be comparable, giving rise to mixed inertial-gravity modes. We develop a nonperturbative numerical spectral code to compute the frequencies and tidal coupling coefficients of these modes. We then calculate the phase shift in the gravitational waveform due to each resonance during binary inspiral. Given the uncertainties in the NS equation of state and stratification property, we adopt polytropic NS models with a parametrized stratification. We derive relevant scaling relations and survey how the phase shift depends on various properties of the NS. We find that for canonical NSs (with mass $M=1.4M_{\odot }$ and radius $R=10\mathrm{km}$) and modest rotation rates ($\lesssim 300\mathrm{Hz}$), the gravitational wave phase shift due to a resonance is generally less than 0.01 radian. But the phase shift is a strong function of $R$ and $M$, and can reach a radian or more for low-mass NSs with larger radii ($R\gtrsim 15\mathrm{km}$). Significant phase shift can also be produced when the combination of stratification and rotation gives rise to a very low frequency ($\lesssim 20\mathrm{Hz}$ in the inertial frame) modified g-mode. As a by-product of our precise calculation of oscillation modes in rotating NSs, we find that some inertial modes can be strongly affected by stratification; we also find that the $m=1\mathrm{r}$-mode, previously identified to have a small but finite inertial-frame frequency based on the Cowling approximation, in fact has essentially zero frequency, and therefore cannot be excited during the inspiral phase of NS binaries.

We calculate the rate of thermal Schwinger pair production at arbitrary coupling in weak external fields. Our calculations are valid independently of many properties of the charged particles produced, in particular their spin and whether they are electric or magnetic. Using the worldline formalism, we calculate the logarithm of the rate to leading order in the weak external field and to all orders in virtual photon exchange, taking us beyond the perturbative expansion about the leading order, weak coupling result.

We analyze the interplay between leptogenesis and residual symmetry in the framework of a model with two right-handed neutrinos. Working in the flavor basis, we show that all the leptogenesis $CP$ asymmetries are vanishing for the case of two residual $CP$ transformations or a cyclic residual flavor symmetry in the neutrino sector. If a single remnant $CP$ transformation is preserved in the neutrino sector, the lepton mixing matrix is determined up to a real orthogonal matrix multiplied from the right side. The $R$-matrix is found to depend on only one real parameter. It can take three viable forms, and each entry is either real or purely imaginary. The baryon asymmetry is generated entirely by the $CP$ violating phases in the mixing matrix in this scenario. We perform a comprehensive study for the $\mathrm{\Delta }(6n^2)$ flavor group and $CP$ symmetry which are broken into a single remnant $CP$ transformation in the neutrino sector and an Abelian subgroup in the charged lepton sector. The results for lepton flavor mixing and leptogenesis are presented.

A higher moment analysis of multiplicity distribution is performed using the Weibull description of particle production in $pp(p\overline{p})$ collisions at Super Proton Synchrotron (SPS) and LHC energies. The calculated normalized moments and factorial moments of Weibull distribution are compared to the measured data. The calculated Weibull moments are found to be in good agreement with the measured higher moments (up to fifth order) reproducing the observed breaking of Koba, Nielsen, and Olesen scaling in the data. The moments for $pp$ collisions at $\sqrt{s}=13\mathrm{TeV}$ are also predicted.

The gravitational radiation driven capture (GR capture) between unequal mass black holes without spins has been investigated with numerical relativistic simulations. We adopt the parabolic approximation which assumes that the gravitational wave radiation from a weakly hyperbolic orbit is the same as that from the parabolic orbit having the same pericenter distance. Using the radiated energies from the parabolic orbit simulations, we have obtained the critical impact parameter ($b_{\mathrm{crit}}$) for the GR capture for weakly hyperbolic orbit as a function of initial energy. The most energetic encounters occur around the boundary between the direct merging and the fly-by orbits, and can emit several percent of total initial energy at the peak. When the total mass is fixed, energy and angular momentum radiated in the case of unequal mass black holes are smaller than those of equal mass black holes having the same initial orbital angular momentum for the fly-by orbits. We have compared our results with two different post-Newtonian (PN) approximations, the exact parabolic orbit (EPO) and PN corrected orbit (PNCO). We find that the agreement between the EPO and the numerical relativity breaks down for very close encounters (e.g., $b_{\mathrm{crit}}\lesssim 100\mathrm{M}$), and it becomes worse for higher mass ratios. For instance, the critical impact parameters can differ by more than 50% from those obtained in EPO if the relative velocity at infinity $v_{\infty }$ is larger than 0.1 for the mass ratio of $m_1/m_2=16$. The PNCO gives more consistent results than EPO, but it also underestimates the critical impact parameter for the GR capture at $b_{\mathrm{crit}}\lesssim 40\mathrm{M}$.