We investigate nonresonant thermal leptogenesis in the context of the $SU(5)\times {\mathcal{T}}_{13}$ “asymmetric texture”, where both Dirac and Majorana $CP$ violation arise from a single phase in the tribimaximal seesaw mixing matrix. We show that the baryon asymmetry of the universe can be explained in this model only when flavor effects are considered for right-handed neutrino masses of $\mathcal{O}({10}^{11}–{10}^{12})\mathrm{GeV}$. The sign of the baryon asymmetry also determines the sign of the previously predicted Dirac $\cancel{CP}$ phase $|{\delta }_{CP}|=1.32\pi$, consistent with the latest global fit ${\delta }_{CP}^{\mathrm{PDG}}=1.37\pm 0.17\pi$.

Two-loop effects on the right-handed neutrino masses can have an impact on the low-energy phenomenology, especially when the right-handed neutrino mass spectrum is very hierarchical at the cutoff scale. In this case, the physical masses of the lighter right-handed neutrinos can be dominated by quantum effects induced by the heavier ones. Further, if the heaviest right-handed neutrino mass is at around the Planck scale, two-loop effects on the right-handed neutrino masses generate, through the seesaw mechanism, an active neutrino mass that is in the ballpark of the experimental values. In this paper we investigate extensions of the Planck-scale lepton number breaking scenario by additional Higgs doublets (inert or not). We find that under reasonable assumptions these models lead simultaneously to an overall neutrino mass scale and to a neutrino mass hierarchy in qualitative agreement with observations.

We study, by means of numerical lattice simulations, the properties of the reconfinement phase transition taking place in trace deformed $SU(3)$ Yang-Mills theory defined on ${\mathbb{R}}^3\times S^1$, in which center symmetry is recovered even for small compactification radii. We show, by means of a finite size scaling analysis, that the reconfinement phase transition is first order, like the usual $SU(3)$ thermal phase transition. We then investigate two different physical phenomena, which are known to characterize the standard confinement/deconfinement phase transition, namely the condensation of thermal magnetic monopoles and the change in the localization properties of the eigenmodes of the Dirac operator. Regarding the latter, we show that the mobility edge signalling the Anderson-like transition in the Dirac spectrum vanishes as one enters the reconfined phase, as it happens in the standard confined phase. Thermal monopoles, instead, show a peculiar behavior: their density decreases going through reconfinement, at odds with the standard thermal theory; nonetheless, they condense at reconfinement, like at the usual confinement transition. The coincidence of monopole condensation and Dirac mode delocalization, even in a framework different from that of the standard confinement transition, suggests the existence of a strict link between them.

We calculate the production cross section and the transverse single-spin asymmetry for pion in $p^{\uparrow }+p\to {\pi }^0+X$. Our computation is based on existence of the instanton induced effective quark-gluon and quark-gluon-pion interactions with a strong spin dependency. In this framework we calculate the cross section without using fragmentation functions. We compare predictions of the model with data from RHIC. Our numerical results, based on the instanton liquid model for QCD vacuum, are in agreement with unpolarized cross section data. The asymmetry grows with the transverse momentum of pion $k_t$ in accordance with experimental observations. It reaches a value $\sim 10\%$ but at higher $k_t$ than experiment shows.

The lepton angular distribution coefficients $A_i$ for $Z$ boson production in $pp$ and $\overline{p}p$ collisions have been measured at the LHC and the Tevatron. A recent study showed that many features of the measured angular distribution coefficients, including the transverse momentum ($q_T$) and rapidity dependencies and the violation of the Lam-Tung relation, can be well described using an intuitive geometric approach. In this paper, we extend this geometric approach to describe the angular distribution coefficients for $W$ boson produced in $\overline{p}p$ collisions at the Tevatron. We first compare the data with a perturbative QCD calculation at $\mathcal{O}({\alpha }_s^2)$. We then show that the data and QCD calculations can be well described with the geometric approach. Implications for future studies at the LHC energy are also discussed.

We study the transitions between the different color states of a static quark-antiquark pair, singlet and octet, in a thermal medium. This is done nonperturbatively exploiting the infinite mass limit of QCD. This study is interesting because it can be used for future developments within the framework of effective field theories and because it can be combined with other techniques, like lattice QCD or $\mathrm{AdS}/\mathrm{CFT}$, to gain nonperturbative information about the evolution of quarkonium in a medium. We also study the obtained expressions in the large $N_c$ limit. This allows us to learn lessons that are useful to simplify phenomenological models of quarkonium in a plasma.

The Mu2e and COMET collaborations will search for nucleus-catalyzed muon conversion to positrons (${\mu }^{-}\to e^{+}$) as a signal of lepton number violation. A key background for this search is radiative muon capture where either (1) a real photon converts to an $e^{+}{e}^{-}$ pair “externally” in surrounding material, or (2) a virtual photon mediates the production of an $e^{+}{e}^{-}$ pair “internally.” If the $e^{+}$ has an energy approaching the signal region then it can serve as an irreducible background. In this work we describe how the near end point internal positron spectrum can be related to the real photon spectrum from the same nucleus, which encodes all nontrivial nuclear physics.

Collective coordinates provide a powerful tool for separating collective and elementary excitations, allowing both to be treated in the full quantum theory. The price is a canonical transformation which leads to a complicated starting point for subsequent calculations. Sometimes the collective behavior of a soliton is simple but nontrivial, and one is interested in the elementary excitations. We show that in this case an alternative prescription suffices, in which the canonical transformation is not necessary. The use of a nonperturbative operator which creates a soliton state allows the theory to be constructed perturbatively in terms of the soliton normal modes. We show how translation invariance may be perturbatively imposed. We apply this to construct the two-loop ground state of an arbitrary scalar kink.

A covariant, scalar-tensor gravity is constructed such that the static, spherically symmetric Rezzolla-Zhidenko metric is an exact solution to the theory. The equations describing gravitational perturbations of this spacetime, which represents a generic black hole possessing an arbitrary number of hairs, can then be derived. This allows for a self-consistent study of the associated quasinormal modes. It is shown that mode spectra are tied to not only the non-Einstein parameters in the metric but also to those that appear at the level of the action, and that different branches of the exact theory can, in some cases, predict significantly different oscillation frequencies and damping times. For choices which make the theory appear more like general relativity in some precise sense, we find that a nontrivial Rezzolla-Zhidenko parameter space is permissible under current constraints on fundamental ringdown modes observed by Advanced LIGO.

We point out an association between anomalies in the Hawking quasilocal mass (or, in spherical symmetry, in its better known version, the Misner-Sharp-Hernandez mass) and unphysical properties of the spacetime geometry. While anomalous behaviors show up in certain quantum-corrected black holes, they are not unique to this context and signal serious physical pathologies of isolated gravitating systems in general.

Born-Infeld AdS black hole exhibits a reentrant phase transition for certain values of the Born-Infeld parameter $b$. This behavior is an additional feature compared to the van der Waals like phase transition observed in charged AdS black holes. Therefore, it is worth observing the underlying microscopic origin of this reentrant phase transition. Depending on the value of the parameter $b$, the black hole system has four different cases: no phase transition, a reentrant phase transition with two scenarios, or a van der Waals-like (standard) phase transition. In this article, by employing a novel Ruppeiner geometry method in the parameter space of temperature and volume, we investigate the microstructure of Born-Infeld AdS black hole via the phase transition study, which includes standard and reentrant phase transitions. We find that the microstructures of the black hole that lead to standard and reentrant phase transitions are distinct in nature. The standard phase transition is characterized by the typical RN-AdS microstructure. In this case, the small black hole phase has a dominant repulsive interaction for the low temperature case. Interestingly, during the reentrant phase transition, displayed by the system in a range of pressures for specific $b$ values, the dominant attractive nature of interaction in the microstructure is preserved. Our results suggest that in the reentrant phase transition case, the intermediate black holes behave like a bosonic gas, and in the standard phase transition case the small black holes behave like a quantum anyon gas. In both cases, the large black hole phase displays an interaction similar to the bosonic gas. The critical phenomenon is observed from the curvature scalar, including the signature of the reentrant phase transition.

Gravitational wave observations of compact binary mergers are already providing stringent tests of general relativity and constraints on modified gravity. Ground-based interferometric detectors will soon reach design sensitivity, and they will be followed by third-generation upgrades, possibly operating in conjunction with space-based detectors. How will these improvements affect our ability to investigate fundamental physics with gravitational waves? The answer depends on the timeline for the sensitivity upgrades of the instruments, but also on astrophysical compact binary population uncertainties, which determine the number and signal-to-noise ratio of the observed sources. We consider several scenarios for the proposed timeline of detector upgrades and various astrophysical population models. Using a stacked Fisher matrix analysis of binary black hole merger observations, we thoroughly investigate future theory-agnostic bounds on modifications of general relativity as well as bounds on specific theories. For theory-agnostic bounds, we find that ground-based observations of stellar-mass black holes and LISA observations of massive black holes can each lead to improvements of 2–4 orders of magnitude with respect to present gravitational wave constraints, while multiband observations can yield improvements of 1–6 orders of magnitude. We also clarify how the relation between theory-agnostic and theory-specific bounds depends on the source properties.

We explore the cosmological signals of theories in which the neutrinos decay into invisible dark radiation after becoming nonrelativistic. We show that, in this scenario, near-future large-scale structure measurements from the Euclid satellite, when combined with cosmic microwave background data from Planck, may allow an independent determination of both the lifetime of the neutrinos and the sum of their masses. These parameters can be independently determined, because the Euclid data will cover a range of redshifts, allowing the growth of structure over time to be tracked. If neutrinos are stable on cosmological timescales, these observations can improve the lower limit on the neutrino lifetime by 7 orders of magnitude, from $\mathcal{O}(10)$ to $2\times {10}^8\mathrm{yr}$ (95% C.L.), without significantly affecting the measurement of neutrino mass. On the other hand, if neutrinos decay after becoming nonrelativistic but on timescales less than $\mathcal{O}(100)$ million years, these observations may allow not just the first measurement of the sum of neutrino masses, but also the determination of the neutrino lifetime from cosmology.

We investigate the weak and strong deflection gravitational lensing by the hairy black holes in the Einstein-scalar-Gauss-Bonnet (EsGB) gravity with five types of coupling functions (quadratic, cubic, quartic, inverse-polynomial, and logarithmic), which can evade the no-hair theorem. The lensing observables are found and the possibility of detecting the effects of the scalar hair is analyzed. We find that all of the shadows cast by these black holes are consistent with the measurement by the Event Horizon Telescope, while other lensing observables are beyond the present capacity. Therefore, it is currently impossible to distinguish these black holes from the Schwarzschild one and from each other merely by their lensing signatures, leaving testing the EsGB gravity by gravitational lensing until new technology is available.

We present a search for axionlike polarization oscillations in the cosmic microwave background (CMB) with observations from the Keck Array. A local axion field induces an all-sky, temporally sinusoidal rotation of CMB polarization. A CMB polarimeter can thus function as a direct-detection experiment for axionlike dark matter. We develop techniques to extract an oscillation signal. Many elements of the method are generic to CMB polarimetry experiments and can be adapted for other datasets. As a first demonstration, we process data from the 2012 observing season to set upper limits on the axion-photon coupling constant in the mass range ${10}^{-21}–{10}^{-18}\mathrm{eV}$, which corresponds to oscillation periods on the order of hours to months. We find no statistically significant deviations from the background model. For periods larger than 24 hr (mass $m<4.8\times {10}^{-20}\mathrm{eV}$), the median 95% confidence upper limit is equivalent to a rotation amplitude of 0.68°, which constrains the axion-photon coupling constant to $g_{\varphi \gamma }<(1.1\times {10}^{-11}{\mathrm{GeV}}^{-1})m/({10}^{-21}\mathrm{eV})$, if axionlike particles constitute all of the dark matter. The constraints can be improved substantially with data already collected by the BICEP series of experiments. Current and future CMB polarimetry experiments are expected to achieve sufficient sensitivity to rule out unexplored regions of the axion parameter space.

Nonzero topological charge is prohibited in the chiral limit of continuum gauge-fermion systems because any unpaired instanton would create a zero mode of the Dirac operator. On the lattice, however, the geometric $Q_{\mathrm{geom}}=⟨F\tilde{F}⟩/32{\pi }^2$ definition of the topological charge does not necessarily vanish in the chiral limit even when the gauge fields are smoothed for example with gradient flow. Small vacuum fluctuations (dislocations) not seen by the fermions may be promoted to instantonlike objects by the gradient flow. We demonstrate that these artifacts of the flow cause the gradient flow renormalized gauge coupling to increase and appear to run faster. In step-scaling studies such strong coupling artifacts contribute a term that might not follow perturbative scaling. The usual $a/L\to 0$ continuum limit extrapolations can hence lead to incorrect results. In this paper we investigate these topological lattice artifacts in the massless SU(3) 10-flavor system with domain wall fermions and the massless 8-flavor system with staggered fermions. For both systems we observe that in the range of strong coupling Symanzik gradient flow exhibits more lattice artifacts compared to Wilson gradient flow. We demonstrate how this artifact impacts the determination of the renormalized gauge coupling and the step-scaling $\beta$ function.

We predict the spectrum of the four $1S$ and eight $1P$ nonstrange and strange states in the beauty meson family in the context of effective field theory. By the union of heavy quark effective theory and chiral perturbation theory, the mass formalisms for the heavy-light mesons are defined. Our analysis uses mass expressions involving, for the first time, the full leading self-energy corrections and leading power corrections to the heavy quark and chiral limits. The counterterms present in these expressions are fitted using charm data and then used to predict the masses of the analog beauty meson states. The observed spectrum of the ground state, $B_{(s)}^{(*)}$, and excited, $B_{(s)1}$ and $B_{(s)2}^{*}$, beauty mesons are well reproduced in our theoretical calculations. The excited scalar, $B_{(s)0}^{*}$, and axial-vector, $B_{(s)1}^{\prime }$, beauty mesons have not yet been discovered. Hopefully our predictions may provide valuable clues to further experimental exploration of these missing resonances.

This article concerns the problems regarding different lattice regularization techniques for the matter fields of Hamiltonian constraints defined in the framework of loop quantum gravity. The analysis is formulated in the phase space-reduced cosmological model of the hypothetical theory of canonical quantum general relativity. This article explains why a different than links-related lattice smearing of fields leads to a local violation of general covariance. This happens by assuming, for instance, the nodes-related smearing. Therefore, this problem occurs in the case of any polymerlike scalar field quantization method by breaking the background independence of the semiclassical predictions. In consequence, the diffeomorphism symmetry that depends on a links distribution is broken locally at the level of generally relativistic corrections. Moreover, by using the phase space-reduced gauge fixing technique to analyze this issue, the results are general and they concern any coupling with the links-regularized gravitational degrees of freedom in loop quantum gravity. Therefore, they lead to the following no-go conclusion. Any lattice smearing of matter, not defined by using the geometrical distribution specified by the links-fluxes duality, violates the general principle of relativity.

The goal of the present paper is to understand whether it is possible to define interacting quantum field theory in global anti–de Sitter spacetime with Lorentzian signature, in its covering spacetime (whose time coordinate is not periodic) and in its Poincaré patch. We show that in global anti–de Sitter spacetime there are certain problems with defining quantum field theory properly. This is due to an additional UV singularity of the Feynman propagator which is sitting on the light cone emanating from the antipodal point of the source. There is no such singularity in flat spacetime. At the same time quantum field theory in the Poincaré region of the anti–de Sitter (AdS) spacetime can be well defined and is related to the one in Euclidean AdS via the analytical continuation. In principle one can also define and analytically continue quantum field theory in the covering anti–de Sitter spacetime. However, to do that one has to use an unusual $i\epsilon$ prescription in the Feynman propagator which cannot be used in loop calculations in nonstationary situations.

Inspired in metamaterials, we present a covariant mechanics for particles in Kleinian spacetime and show some of its effects, such as time contraction and length dilatation. We present the new expressions for relativistic momentum and energy for a pointlike particle. To illustrate the new mechanics, we describe the particle motion under a uniform Newtonian gravitational field. We also revisit the free spin-half particle problem in Kleinian spacetime, discuss some quantum implications, like the constraint on the dispersion relation for Weyl fermions, and adapt a metamaterial analog system to Klein spacetime.