We find the fingerprints of the Goldstino associated to spontaneous supersymmetry breaking in a prototype holographic model for a strongly coupled field theory. The Goldstino massless pole arises in two-point correlators of the supercurrent, due to contact terms in supersymmetry Ward identities. We show how these contact terms are obtained from the holographic renormalization of the gravitino sector, independently of the details of the bulk background solution. For completeness, we prove the existence of a family of such solutions in a simple supergravity model.

We consider a gauge theory action for continuous spin particles formulated in a spacetime enlarged by an extra coordinate recently proposed by Schuster and Toro. It requires one scalar gauge field and has two local symmetries. We show that the local symmetries are reducible in the sense that the parameters also have a local symmetry. Using reducibility we get an action which has two scalar gauge fields and a reducible but simpler local symmetry. We then show how this action and equations of motion are related to previously proposed formulations for continuous spin particles and higher spin theories. We also discuss the physical contents of each formulation to reveal the physical degrees of freedom.

We introduce an effective quark-meson-nucleon model for the QCD phase transitions at finite baryon density. The nucleon and the quark degrees of freedom are described within a unified framework of a chiral linear sigma model. The deconfinement transition is modeled through a simple modification of the distribution functions of nucleons and quarks, where an additional auxiliary field, the bag field, is introduced. The bag field plays a key role in converting between the nucleon and the quark degrees of freedom. The model predicts that the chiral and the deconfinement phase transitions are always separated. Depending on the model parameters, the chiral transition occurs in the baryon density range of $(1.5-15.5)n_0$, while the deconfinement transition occurs above $5n_0$, where $n_0$ is the saturation density.

We present a variational principle for relativistic hydrodynamics with gauge-anomaly terms for a fluid coupled to an Abelian background gauge field. For this we utilize the Clebsch parametrization of the velocity field. We also set up the Hamiltonian formulation and the canonical framework for the theory. While the equations of motion only involve the density and velocity fields, i.e., the Clebsch potentials only appear in the combination which is the velocity field, the generators of symmetry transformations (including the Hamiltonian) depend explicitly on one of the Clebsch potentials, if the background field is time-dependent. For the special case of time-independent background fields, this feature is absent.

The discovery of the Higgs boson suggests that neutrinos also get their mass from spontaneous symmetry breaking. In the simplest ungauged lepton-number scheme, the Standard Model Higgs now has two other partners: a massive $CP$-even scalar, and the massless Nambu-Goldstone boson, called the Majoron. For weak-scale breaking of lepton number the invisible decays of the $CP$-even Higgs bosons to the Majoron lead to potentially copious sources of events with large missing energy. Using LHC results, we study how the constraints on invisible decays of the Higgs boson restrict the relevant parameters, substantially extending those previously derived from LEP and potentially shedding light on the scale of spontaneous lepton-number violation.

Using $2.92{\mathrm{fb}}^{-1}$ of electron-positron annihilation data collected at $\sqrt{s}=3.773\mathrm{GeV}$ with the BESIII detector, we report the results of a search for the flavor-changing neutral current process $D^0\to \gamma \gamma$ using a double-tag technique. We find no signal and set an upper limit at 90% confidence level for the branching fraction of $\mathcal{B}(D^0\to \gamma \gamma )<3.8\times {10}^{-6}$. We also investigate $D^0$-meson decay into two neutral pions, obtaining a branching fraction of $\mathcal{B}(D^0\to {\pi }^0{\pi }^0)=(8.24\pm 0.21(\text{stat})\pm 0.30(\text{syst}))\times {10}^{-4}$, the most precise measurement to date and consistent with the current world average.

An analysis of the decays of $B^{\mp }\to D{K}^{\mp }$ and $B^{\mp }\to D{\pi }^{\mp }$ is presented in which the $D$ meson is reconstructed in the three-body final states $K^{\mp }{\pi }^{\pm }{\pi }^0$, ${\pi }^{+}{\pi }^{-}{\pi }^0$ and $K^{+}{K}^{-}{\pi }^0$. Using data from LHCb corresponding to an integrated luminosity of $3.0{\mathrm{fb}}^{-1}$ of $pp$ collisions, measurements of several $CP$ observables are performed. First observations are obtained of the suppressed Atwood-Dunietz-Soni decay $B^{\mp }\to [{\pi }^{\mp }{K}^{\pm }{\pi }^0{]}_D{\pi }^{\mp }$ and the quasi-Gronau-London-Wyler decay $B^{\mp }\to [K^{+}{K}^{-}{\pi }^0{]}_D{\pi }^{\mp }$. The results are interpreted in the context of the unitarity triangle angle $\gamma$ and related parameters.

We consider the action of a non-Abelian $T$ duality on backgrounds with an ${\mathrm{AdS}}_5$ factor in type IIA supergravity, finding a new type IIB background, as well as the non-Abelian $T$-dual of a domain wall solution which has as limits the non-Abelian $T$-dual of ${\mathrm{AdS}}_5\times T^{1,1}$ and the non-Abelian $T$-dual of ${\mathrm{AdS}}_3\times {\mathbb{R}}^2\times S^2\times S^3$. We explore some consequences of non-Abelian $T$ duality for the dual conformal field theories.

We study the corpuscular model of an evaporating black hole consisting of a specific quantum state for a large number $N$ of self-confined bosons. The single-particle spectrum contains a discrete ground state of energy $m$ (corresponding to toy gravitons forming the black hole), and a gapless continuous spectrum (to accommodate for the Hawking radiation with energy $\omega >m$). Each constituent is in a superposition of the ground state and a Planckian distribution at the expected Hawking temperature in the continuum. We first find that, assuming the Hawking radiation is the leading effect of the internal scatterings, the corresponding $N$-particle state can be collectively described by a single-particle wave function given by a superposition of a total ground state with energy $M=Nm$ and a Planckian distribution for $E>M$ at the same Hawking temperature. From this collective state, we compute the partition function and obtain an entropy which reproduces the usual area law with a logarithmic correction precisely related with the Hawking component. By means of the horizon wave function for the system, we finally show the backreaction of modes with $\omega >m$ reduces the Hawking flux. Both corrections, to the entropy and to the Hawking flux, suggest the evaporation properly stops for vanishing mass, if the black hole is in this particular quantum state.

Certain local thermal observables are considered in well-known examples of spatially open FRW spaces: Milne, open de Sitter and anti–de Sitter as well as Einstein static universes. Another value for fixing the ambiguity in defining the Wick square and, hence, the local temperature is motivated in the last example. Physical consequences of that choice are discussed for static and conformal vacua in those spaces.

We study the inflationary evolution of a scalar field $h$ with an unstable potential for the case where the Hubble parameter $H$ during inflation is larger than the instability scale ${\mathrm{\Lambda }}_I$ of the potential. Quantum fluctuations in the field of size $\delta h\sim \frac{H}{2\pi }$ imply that the unstable part of the potential is sampled during inflation. We investigate the evolution of these fluctuations to the unstable regime and in particular whether they generate cosmological defects or even terminate inflation. We apply the results of a toy scalar model to the case of the Standard Model Higgs boson, the quartic of which evolves to negative values at high scales, and extend previous analyses of Higgs dynamics during inflation utilizing statistical methods to a perturbative and fully gauge-invariant formulation. We show that the dynamics are controlled by the renormalization group-improved quartic coupling $\lambda (\mu )$ evaluated at a scale $\mu =H$, such that Higgs fluctuations are enhanced by the instability if $H>{\mathrm{\Lambda }}_I$. Even if $H>{\mathrm{\Lambda }}_I$, the instability in the Standard Model Higgs potential does not end inflation; instead the universe slowly sloughs off crunching patches of space that never come to dominate the evolution. As inflation proceeds past 50 $e$-folds, a significant proportion of patches exits inflation in the unstable vacuum, and as much as 1% of the spacetime can rapidly evolve to a defect. Depending on the nature of these defects, however, the resulting universe could still be compatible with ours.

We compute the sensitivity to dark matter annihilations for the forthcoming large Cherenkov Telescope Array (CTA) in several primary channels and over a range of dark matter masses from 50 GeV up to 80 TeV. For all channels, we include inverse Compton scattering of $e^{\pm }$ by dark matter annihilations on the ambient photon background, which yields substantial contributions to the overall $\gamma$-ray flux. We improve the analysis over previous work by: (i) implementing a spectral and morphological analysis of the $\gamma$-ray emission; (ii) taking into account the most up-to-date cosmic ray background obtained from a full CTA Monte Carlo simulation and a description of the diffuse astrophysical emission; and (iii) including the systematic uncertainties in the rich observational CTA data sets. We find that our spectral and morphological analysis improves the CTA sensitivity by roughly a factor 2. For the hadronic channels, CTA will be able to probe thermal dark matter candidates over a broad range of masses if the systematic uncertainties in the data sets will be controlled better than the percent level. For the leptonic modes, the CTA sensitivity will be well below the thermal value of the annihilation cross-section. In this case, even with larger systematics, thermal dark matter candidates up to masses of a few TeV will be easily studied.

In supersymmetric models with gluinos $m(\tilde{g})\sim 1000-2000\mathrm{GeV}$, new physics searches based on cascade decay products of the gluino are viable at the next run of the LHC. We investigate a scenario where the light stop is lighter than the gluino and both are lighter than all other squarks, and show that its signal can be established using multi $b$-jet, multi $W$ and/or multi-lepton final state topologies. We then utilize both boosted and conventional jet topologies in the final state in conjunction with di-tau production as a probe of the stau-neutralino coannihilation region responsible for the model’s dark matter content. This study is performed in the specific context of one such phenomenologically viable model named no-scale $\mathcal{F}\text{−}SU(5)$.

We present a mechanism where a particle asymmetry in one sector is used to generate an asymmetry in another sector. The two sectors are not coupled through particle number violating interactions and are not required to be in thermal contact with each other. When this mechanism is applied to baryogenesis in asymmetric dark matter models, we find that the dark matter particles can be extremely light, e.g. much lighter than an eV, and that in some cases there is no need to annihilate away the symmetric component of dark matter. We discuss a concrete realization of the mechanism with signals in direct detection, at the LHC, at $B$-factories, or in future beam dump experiments.

In the present work we have studied the chiral odd generalized parton distributions in the impact parameter space by assuming a flexible parametrization in a quark-diquark model. In order to obtain the explicit contributions from the up and down quarks, we have considered both the scalar (spin-0) and the axial-vector (spin-1) configurations for the diquark. We have also studied the spin densities for the up and down quarks in this model for monopole, dipole and quadrupole contributions for unpolarized and polarized quarks in unpolarized and polarized protons.

We study the consequences of the $Z_2$ symmetry behind the $\mu$-$\tau$ universality in the neutrino mass matrix. We then implement this symmetry in the type-I seesaw mechanism and show how it can accommodate all sorts of lepton mass hierarchies and generate enough lepton asymmetry to interpret the observed baryon asymmetry in the universe. We also show how a specific form of a high-scale perturbation is kept when translated via the seesaw into the low scale domain, where it can accommodate the neutrino mixing data. We finally present a realization of the high scale perturbed texture through the addition of matter and extra exact symmetries.

Starting with the high scale mixing unification hypothesis, we investigate the renormalization-group evolution of mixing parameters and masses for Dirac-type neutrinos. Following this hypothesis, the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing angles and phase are taken to be identical to the Cabibbo-Kobayashi-Maskawa (CKM) ones at a unifying high scale. Then they are evolved to a low scale using renormalization-group equations. The notable feature of this hypothesis is that renormalization-group evolution with quasidegenerate mass pattern can explain largeness of leptonic mixing angles even for Dirac neutrinos. The renormalization-group evolution “naturally” results in a nonzero and small value of leptonic mixing angle ${\theta }_{13}$. One of the important predictions of this work is that the mixing angle ${\theta }_{23}$ is nonmaximal and lies only in the second octant. We also derive constraints on the allowed parameter range for the supersymmetry breaking and unification scales for which this hypothesis works. The results are novel and can be tested by present and future experiments.

Over the past three decades, considerable effort has been devoted to studying the rich and diverse phenomenologies of heterotic strings exhibiting spacetime supersymmetry. Unfortunately, during this same period, there has been relatively little work studying the phenomenologies associated with their nonsupersymmetric counterparts. The primary reason for this relative lack of attention is the fact that strings without spacetime supersymmetry are generally unstable, exhibiting large one-loop dilaton tadpoles. In this paper, we demonstrate that this hurdle can be overcome in a class of tachyon-free four-dimensional string models realized through coordinate-dependent compactifications. Moreover, as we shall see, it is possible to construct models in this class whose low-lying states resemble the Standard Model (or even potential unified extensions thereof)—all without any light superpartners, and indeed without supersymmetry at any energy scale. The existence of such models thus opens the door to general studies of nonsupersymmetric string phenomenology, and in this paper we proceed to discuss a variety of theoretical and phenomenological issues associated with such nonsupersymmetric strings. On the theoretical side, we discuss the finiteness properties of such strings, the general characteristics of their mass spectra, the magnitude and behavior of their one-loop cosmological constants, and their interpolation properties. By contrast, on the phenomenological side, the properties we discuss are more model-specific and include their construction techniques, their natural energy scales, their particle and charge assignments, and the magnitudes of their associated Yukawa couplings and scalar masses.

We present the construction of a physical Hamiltonian operator in the deparametrized model of loop quantum gravity coupled to a free scalar field. This construction is based on the use of the recently introduced curvature operator, and on the idea of so-called special loops. We discuss in detail the regularization procedure and the assignment of the loops, along with the properties of the resulting operator. We compute the action of the squared Hamiltonian operator on spin network states, and close with some comments and outlooks.