By imposing suitable junction conditions on a spacelike hypersurface, we obtain a two-parameter family of possible static configurations from gravitational collapse. These exemplify a new class of naked singularities. We show that these admit a consistent description via a two-fluid model, one of which might be dust. We then study lensing and accretion disk properties of our solution and point out possible differences with black hole scenarios. The distinctive features of our solution compared to the existing naked singularity solutions in the literature are discussed.

The hallmark way to search for electroweakinos in natural supersymmetry at the LHC involves the trilepton plus missing energy (${\cancel{E}}_T$) final state. This approach assumes an electroweakino mass hierarchy that allows for cascade decays leading to a final state of $W^{\pm }{Z}^0$ plus ${\cancel{E}}_T$. There are, however, situations when that decay pattern may not exist, such as when a chargino is the lightest electroweakino and the lightest supersymmetric particle is the gravitino. In regions of the parameter space where this ordering occurs, the production of any combination of neutralino/chargino leads to a $W^{+}{W}^{-}+{\cancel{E}}_T+X$ final state, where $X$ could be additional jets or leptons. If $X$ is soft, then all neutralino/chargino production modes fall into the same experimental final state, ${\ell }^{+}{\ell }^{-}+{\cancel{E}}_T$. ATLAS and CMS have $W^{+}({\ell }^{+}\nu )W^{-}({\ell }^{-}\overline{\nu })+{\cancel{E}}_T$ searches, but their interpretation assumes a spectrum consisting of an isolated charged state. In this paper, we identify the circumstances under which natural supersymmetry models can avoid $W^{\pm }{Z}^0+{\cancel{E}}_T$ bounds. For scenarios that escape $W^{\pm }{Z}^0+{\cancel{E}}_T$, we then recast the latest ATLAS $W^{+}{W}^{-}+{\cancel{E}}_T$ search, taking into account all the states that contribute to the same signal. Assuming the lightest supersymmetric particle is massless, we find a bound of 460 GeV for a Higgsino-like degenerate doublet. Finally, we extend our arguments to a nonsupersymmetric simplified model containing new electroweak-scale $SU(2{)}_w$ doublets and singlets.

Two-Higgs-doublet models usually consider an ad-hoc ${\mathbb{Z}}_2$ discrete symmetry to avoid flavor changing neutral currents. We consider a new class of two-Higgs-doublet models where ${\mathbb{Z}}_2$ is enlarged to the symmetry group $\mathcal{F}⋊{\mathbb{Z}}_2$, i.e., an inner semidirect product of a discrete symmetry group $\mathcal{F}$ and ${\mathbb{Z}}_2$. In such a scenario, the symmetry constrains the Yukawa interactions but goes unnoticed by the scalar sector. In the most minimal scenario, ${\mathbb{Z}}_3⋊{\mathbb{Z}}_2=D_3$, flavor changing neutral currents mediated by scalars are absent at tree and one-loop level, while at the same time predictions to quark and lepton mixing are obtained, namely a trivial Cabibbo-Kobayashi-Maskawa matrix and a Pontecorvo-Maki-Nakagawa-Sakata matrix (upon introduction of three heavy right-handed neutrinos) containing maximal atmospheric mixing. Small extensions allow to fully reproduce mixing parameters, including cobimaximal mixing in the lepton sector (maximal atmospheric mixing and a maximal charge-parity violating phase).

We investigate the relation between the realization of center symmetry and the dependence on the topological parameter $\theta$ in $SU(N)$ Yang-Mills theories, exploiting trace deformations as a tool to regulate center symmetry breaking in a theory with a small compactified direction. We consider, in particular, $SU(4)$ gauge theory, which admits two possible independent deformations, and study, as a first step, its phase diagram in the deformation plane for two values of the inverse compactified radius going up to $L^{-1}\sim 500\mathrm{MeV}$, comparing the predictions of the effective one-loop potential of the Polyakov loop with lattice results. The $\theta$-dependence of the various phases is then addressed, up to the fourth order in $\theta$, by numerical simulations; results are found to coincide, within statistical errors, with those of the standard confined phase iff center symmetry is completely restored and independently of the particular way this happens, i.e., either by local suppression of the Polyakov loop traces or by long range disorder.

We reconsider the contribution due to $\pi a_1$ mixing to the anomalous $\gamma \to {\pi }^{+}{\pi }^0{\pi }^{-}$ amplitude from the standpoint of the low-energy theorem $F^{\pi }=e{f}_{\pi }^2{F}^{3\pi }$, which relates the electromagnetic form factor $F_{{\pi }^0\to \gamma \gamma }=F^{\pi }$ with the form factor $F_{\gamma \to {\pi }^{+}{\pi }^0{\pi }^{-}}=F^{3\pi }$ both taken at vanishing momenta of mesons. Our approach is based on a recently proposed covariant diagonalization of $\pi a_1$ mixing within a standard effective QCD-inspired meson Lagrangian obtained in the framework of the Nambu-Jona-Lasinio model. We show that the two surface terms appearing in the calculation of the anomalous triangle quark diagrams or AVV- and AAA-type (A, axial-vector; V, vector) amplitudes are uniquely fixed by this theorem. As a result, both form factors $F^{\pi }$ and $F^{3\pi }$ are not affected by the $\pi a_1$ mixing, but the concept of vector meson dominance fails for $\gamma \to {\pi }^{+}{\pi }^0{\pi }^{-}$.

In this paper we study the real-time evolution of heavy quarkonium in the quark-gluon plasma (QGP) on the basis of the open quantum systems approach. In particular, we shed light on how quantum dissipation affects the dynamics of the relative motion of the quarkonium state over time. To this end we present a novel nonequilibrium master equation for the relative motion of quarkonium in a medium, starting from Lindblad operators derived systematically from quantum field theory. In order to implement the corresponding dynamics, we deploy the well established quantum state diffusion method. In turn we reveal how the full quantum evolution can be cast in the form of a stochastic nonlinear Schrödinger equation. This for the first time provides a direct link from quantum chromodynamics to phenomenological models based on nonlinear Schrödinger equations. Proof of principle simulations in one dimension show that dissipative effects indeed allow the relative motion of the constituent quarks in a quarkonium at rest to thermalize. Dissipation turns out to be relevant already at early times well within the QGP lifetime in relativistic heavy ion collisions.

We analyze the decays ${\tau }^{-}\to K^{-}({\eta }^{(\prime )},K^0){\nu }_{\tau }$ within an effective-field theory that includes the most general interactions between Standard Model fields up to dimension six, assuming left-handed neutrinos. In particular, we examine different interesting phenomenological observables, i.e., decay spectra and branching ratio, Dalitz plot distributions, and the forward-backward asymmetry, to explore the sensitivity of the corresponding decays to the effects of nonstandard interactions. A controlled theoretical input on the Standard Model hadronic form factors, based on chiral symmetry, dispersion relations, data, and asymptotic QCD properties, has allowed us to set bounds on the new physics scalar and tensor effective couplings using the measured branching ratios. These are found to be in line with the findings of our series of previous analyses of two-meson tau decays and less precise than the constraints obtained from semileptonic kaon decays. In order to set stringent limits on these couplings, we will use all available experimental data of all possible dimeson tau decays. This is our next step plan, that we hope to be of interest for future experimental analyses of these decays.

We explore the metric space of jets using public collider data from the CMS experiment. Starting from $2.3{\mathrm{fb}}^{-1}$ of proton-proton collisions at $\sqrt{s}=7\mathrm{TeV}$ collected at the Large Hadron Collider in 2011, we isolate a sample of 1,690,984 central jets with transverse momentum above 375 GeV. To validate the performance of the CMS detector in reconstructing the energy flow of jets, we compare the CMS Open Data to corresponding simulated data samples for a variety of jet kinematic and substructure observables. Even without detector unfolding, we find very good agreement for track-based observables after using charged hadron subtraction to mitigate the impact of pileup. We perform a range of novel analyses, using the “energy mover’s distance” (EMD) to measure the pairwise difference between jet energy flows. The EMD allows us to quantify the impact of detector effects, visualize the metric space of jets, extract correlation dimensions, and identify the most and least typical jet configurations. To facilitate future jet studies with CMS Open Data, we make our datasets and analysis code available, amounting to around two gigabytes of distilled data and one hundred gigabytes of simulation files.

We discuss how to extract the Pomeron-Pomeron-$f_2(1270)$ [$\mathbb{P}\mathbb{P}{f}_2(1270)]$ coupling within the tensor-Pomeron model. The general $\mathbb{P}\mathbb{P}{f}_2(1270)$ coupling is a combination of seven basic couplings (tensorial structures). To study these tensorial structures, we propose to measure the central-exclusive production of a ${\pi }^{+}{\pi }^{-}$ pair in the invariant mass region of the $f_2(1270)$ meson. An analysis of angular distributions in the ${\pi }^{+}{\pi }^{-}$ rest system, using the Collins-Soper and the Gottfried-Jackson frames, turns out to be particularly relevant for our purpose. For both frames, the $\cos {\theta }_{{\pi }^{+}}$ and ${\varphi }_{{\pi }^{+}}$ distributions are discussed. We find that the azimuthal angle distributions in these frames are fairly sensitive to the choice of the $\mathbb{P}\mathbb{P}{f}_2$ coupling. We show results for the resonance case alone as well as when the dipion continuum is included. We show the influence of the experimental cuts on the angular distributions in the context of dedicated experimental studies at RHIC and LHC energies. Absorption corrections are included for our final distributions.

We study the effect of various perturbative and nonperturbative QCD corrections on the free nucleon structure functions [$F_{iN}^{WI}(x,Q^2);i=1–3$] and their implications in the determination of nuclear structure functions. The evaluation of the nucleon structure functions has been performed by using the MMHT 2014 parton distribution functions (PDFs) parametrization, and the target mass correction (TMC) and higher twist (HT) effects are incorporated following the works of Schienbein et al. and Dasgupta et al., respectively. These nucleon structure functions are taken as input in the determination of nuclear structure functions. The numerical calculations for the ${\nu }_l/{\overline{\nu }}_l\text{−}A$ deep inelastic scattering (DIS) process have been performed by incorporating the nuclear medium effects like Fermi motion, binding energy, nucleon correlations, mesonic contributions, shadowing, and antishadowing in several nuclear targets such as carbon, polystyrene scintillator, iron, and lead, which are being used in $\mathrm{MINER}\nu \mathrm{A}$, and in argon nuclei, which is relevant for the ArgoNeuT and DUNE experiments. The differential scattering cross sections $\frac{d^2{\sigma }_A^{WI}}{dxdy}$ and $(\frac{d{\sigma }_A^{WI}}{dx}/\frac{d{\sigma }_{CH}^{WI}}{dx})$ have also been studied in the kinematic region of the $\mathrm{MINER}\nu \mathrm{A}$ experiment. The theoretical results are compared with the recent experimental data of $\mathrm{MINER}\nu \mathrm{A}$ and the earlier data of the NuTeV, CCFR, CDHSW, and CHORUS Collaborations. Moreover, a comparative analysis of the present results for the ratio $(\frac{d{\sigma }_A^{WI}}{dx}/\frac{d{\sigma }_{CH}^{WI}}{dx})$, and the results from the Monte Carlo (MC) generator GENIE and other phenomenological models of Bodek and Yang, and Cloet et al., has been performed in the context of the $\mathrm{MINER}\nu \mathrm{A}$ experiment. The predictions have also been made for the ${\overline{\nu }}_l\text{−}A$ cross section relevant for the $\mathrm{MINER}\nu \mathrm{A}$ experiment.

We consider Einstein gravity with the addition of $R^2$ and $R^{\mu \nu }{R}_{\mu \nu }$ interactions in the context of effective field theory, and the corresponding scattering amplitudes of gravitons and minimally coupled heavy scalars. First, we recover the known fact that graviton amplitudes are the same as in Einstein gravity. Then we show that all amplitudes with two heavy scalars and an arbitrary number of gravitons are also not affected by these interactions. We prove this by direct computations, using field redefinitions known from earlier applications in string theory, and with a combination of factorization and power-counting arguments. Combined with unitarity, these results imply that, in an effective field theory approach, the Newtonian potential receives neither classical nor quantum corrections from terms quadratic in the curvature.

Diophantine equations are in general undecidable, yet appear readily in string theory. We demonstrate that numerous classes of Diophantine equations arising in string theory are decidable and propose that decidability may propagate through networks of string vacua due to additional structure in the theory. Diophantine equations arising in index computations relevant for D3-instanton corrections to the superpotential exhibit propagation of decidability, with new and existing solutions propagating through networks of geometries related by topological transitions. In the geometries we consider, most divisor classes appear in at least one solution, significantly improving prospects for Kähler moduli stabilization across large ensembles of string compactifications.

Weyl fermions with nonlinear dispersion have appeared in real-world systems, such as in the Weyl semimetals and topological insulators. We consider the most general form of Dirac operators and study its topological properties embedded in the chiral anomaly, in the index theorem, and in the odd-dimensional partition function, by employing the heat kernel. We find that all of these topological quantities are enhanced by a winding number defined by the Dirac operator in the momentum space, regardless of the spacetime dimensions. The chiral anomaly in $d=3+1$, in particular, is also confirmed via the conventional Feynman diagram. These interconnected results allow us to clarify the relationship between the chiral anomaly and the Chern number of the Berry connection, under dispute in some recent literature, and also lead to a compact proof of the Nielsen-Ninomiya theorem.

Using Majorana fermions and elementary mesons we find new massless quantum field theories with weakly interacting ultraviolet fixed points. We also find new classes of large $N$ equivalences among $SU$, $SO$, and $Sp$ gauge theories with different types of matter fields and Yukawa interactions. Results include a triality of asymptotically safe theories and dualities between asymptotically free matter-gauge theories with identical fixed points, phase diagrams, and scaling exponents. Implications for conformal field theory and orbifold reductions are indicated.

Within the superfield formalism, we study the renormalization group improvement of the effective superpotential for the $\mathcal{N}=2$ Chern-Simons-matter theory, explicitly obtain the improved effective potential and discuss the minima of the effective potential and a problem of mass generation in the theory.

We obtain new solutions of Einsteinian cubic gravity coupled to a Maxwell field that describe the near-horizon geometry of charged and rotating black holes. We show that the ${\mathrm{AdS}}_2\times {\mathbb{S}}^2$ near-horizon geometry of Reissner-Nordström black holes receives no corrections, but deviations with respect to the extremal Kerr-Newman solution appear as we turn on the angular momentum. We construct the profile of these corrected geometries using both numerical methods and slowly spinning expansions, but we also find additional solutions that do not reduce to ${\mathrm{AdS}}_2\times {\mathbb{S}}^2$ geometries in any limit and that do not have a counterpart in Einstein gravity. Quite remarkably, we are able to obtain closed-form exact expressions for the area and Wald’s entropy of all of these solutions, and using this result, we analyze the phase space of extremal back holes in this theory. To the best of our knowledge, this is the first time the entropy of a rotating black hole in higher-order gravity has been exactly computed.

We report on a numerical investigation of the stability of scalarized black holes in Einstein-dilaton-Gauss-Bonnet (EdGB) gravity in the full dynamical theory, though restricted to spherical symmetry. We find evidence that for sufficiently small curvature couplings the resulting scalarized black hole solutions are nonlinearly stable. For such small couplings, we show that an elliptic region forms inside these EdGB black hole spacetimes (prior to any curvature singularity), and give evidence that this region remains censored from asymptotic view. However, for coupling values “superextremal” relative to a given black hole mass, an elliptic region forms exterior to the horizon, implying the exterior Cauchy problem is ill-posed in this regime.

We will focus on a model with a scalar-vector coupling and a scalar Kalb-Ramond coupling. The Kalb-Ramond two-form is known to be equivalent to a $U_1$ gauge one-form in five dimensions. The model with both scalar-vector and scalar Kalb-Ramond interactions is hence effectively equivalent to an action with two independent vector fields. As a result, a new set of spherically symmetric black hole solutions will be presented for the scalar-vector Kalb-Ramond theory in five dimensions. We will show that the presence of the scalar fields and gauge fields affect the black hole structure in a nontrivial manner. Related implications will also be discussed in this paper.