A search for highly ionizing particles produced in proton-proton collisions at 8 TeV center-of-mass energy is performed by the ATLAS Collaboration at the CERN Large Hadron Collider. The data set used corresponds to an integrated luminosity of $7.0{\mathrm{fb}}^{-1}$. A customized trigger significantly increases the sensitivity, permitting a search for such particles with charges and energies beyond what was previously accessible. No events were found in the signal region, leading to production cross section upper limits in the mass range 200–2500 GeV for magnetic monopoles with magnetic charge in the range $0.5g_{\mathrm{D}}<|g|<2.0g_{\mathrm{D}}$, where $g_{\mathrm{D}}$ is the Dirac charge, and for stable particles with electric charge in the range $10<|z|<60$. Model-dependent limits are presented in given pair-production scenarios, and model-independent limits are presented in fiducial regions of particle energy and pseudorapidity.

We develop the framework of boundary derivative expansion (BDE) formalism of fluid/gravity correspondence in a compactified D4-brane system, which is a nonconformal background used in top-down holographic QCD models. Such models contain the D4-D6 model and the Sakai-Sugimoto (SS) model, with the background of the compactified black D4 branes under the near-horizon limit. By using the dimensional reduction technique, we derive a 5D Einstein gravity minimally coupled with three scalar fields from the 10D D4-brane background. Following the BDE formalism of fluid/gravity correspondence in the conformal background, we directly derive all the first order transport coefficients for nonconformal gluonic matter. The results of the ratio of the bulk to shear viscosity and the sound speed agree with those obtained from the Green-Kubo method. This agreement guarantees the validity of the BDE formalism of fluid/gravity duality in the nonconformal D-brane background, which can be used to calculate the second order transport coefficients in nonconformal background.

The light-cone gauge is used frequently in string theory as well as gauge theories and gravitation. Loop integrals, however, have to be infrared regulated to remove spurious poles. The most popular and consistent of these infrared regulators is the Mandelstam-Leibbrandt prescription (ML). The calculations with the ML are rather cumbersome, though. In this work, we show that the ML can be replaced by a symmetry of the regulator. This symmetry simplifies the calculations, reducing them to conventional dimensional regularization integrals.

A complete set of exact analytic solutions to the mode equation is found in the region exterior to the acoustic horizon for a class of 1D Bose-Einstein condensate acoustic black holes. From these, analytic expressions for the scattering coefficients and gray-body factor are obtained. The results are used to verify previous predictions regarding the behaviors of the scattering coefficients and gray-body factor in the low-frequency limit.

We derive an ansatz for the five dimensional equal-rotation Kerr-Newman metric that contains two unknown functions. By solving for these functions through perturbation series, we find that the metric can be cast into the Kerr-Shild form in a background that is flat at the spatial infinity.

The quantization of a two-dimensional Hořava theory of gravity without the projectability condition is considered. Our study of the Hamiltonian structure of the theory shows that there are two first-class and two second-class constraints. Then, following Dirac, we quantize the theory by first requiring that the two second-class constraints be strongly equal to zero. This is carried out by replacing the Poisson bracket by the Dirac bracket. The two first-class constraints give rise to the Wheeler-DeWitt equations, which yield uniquely a plane wave solution for the wave function. We also study the classical solutions of the theory and find that the characteristics of classical spacetimes are encoded solely in the phase of the plane wave solution in terms of the extrinsic curvature of the foliations $t=\text{constant}$, where $t$ denotes the globally defined time of the theory.

We present a new pseudospectral code, bamps, for numerical relativity written with the evolution of collapsing gravitational waves in mind. We employ the first-order generalized harmonic gauge formulation. The relevant theory is reviewed, and the numerical method is critically examined and specialized for the task at hand. In particular, we investigate formulation parameters—gauge- and constraint-preserving boundary conditions well suited to nonvanishing gauge source functions. Different types of axisymmetric twist-free moment-of-time-symmetry gravitational wave initial data are discussed. A treatment of the axisymmetric apparent horizon condition is presented with careful attention to regularity on axis. Our apparent horizon finder is then evaluated in a number of test cases. Moving on to evolutions, we investigate modifications to the generalized harmonic gauge constraint damping scheme to improve conservation in the strong-field regime. We demonstrate strong-scaling of our pseudospectral penalty code. We employ the Cartoon method to efficiently evolve axisymmetric data in our $3+1\text{-dimensional}$ code. We perform test evolutions of the Schwarzschild spacetime perturbed by gravitational waves and by gauge pulses, both to demonstrate the use of our black-hole excision scheme and for comparison with earlier results. Finally, numerical evolutions of supercritical Brill waves are presented to demonstrate durability of the excision scheme for the dynamical formation of a black hole.

We construct inflationary models in the context of supergravity with orthogonal nilpotent superfields [Ferrara et al., Phys. Rev. D 93, 043516 (2016)]. When local supersymmetry is gauge-fixed in the unitary gauge, these models describe theories with only a single real scalar (the inflaton), a graviton and a gravitino. Critically, there is no inflatino, no sgoldstino, and no sinflaton in these models. This dramatically simplifies cosmological models which can simultaneously describe inflation, dark energy and SUSY breaking.

Within the Bethe-Salpeter formalism for instantaneous interactions, we describe, along a totally analytic route, the lightest pseudoscalar mesons by quark-antiquark bound states which show at least three indispensable general features—namely, the (almost) masslessness required for pions and kaons to be interpretable as (pseudo-)Goldstone bosons, the suitable asymptotic behavior in the limit of large spacelike relative momenta as determined by the relationship between quark mass function and Bethe-Salpeter amplitudes, and a pointwise behavior for finite spacelike relative momenta suited for guaranteeing color confinement.

The 750 GeV diphoton excess reported by ATLAS and CMS indicates the presence of several pairs of the vectorlike matter multiplets around TeV scale. If that is the case, radiative corrections from the $SU(3)$ gauge interaction significantly change from those of the minimal supersymmetric standard model, and the infrared-free nature of the gauge interaction leads to characteristic supersymmetry mass spectra: a ratio of a squark mass to the gluino mass, and scalar trilinear couplings are enhanced at the low-energy scale. Consequently, even in gaugino mediation models, the Higgs boson mass of 125 GeV is explained with the fairly light gluino of 2–3 TeV, which can be accessible at the LHC.

We investigate the predictions on the mass spectrum and Higgs boson decays in the supersymmetric standard model extended by $U(1{)}_{B-L}$ symmetry (BLSSM). The model requires two singlet Higgs fields, which are responsible for the radiative breaking of $U(1{)}_{B-L}$ symmetry. It predicts degenerate right-handed neutrino masses (1.7–2.2 TeV) as well as the right-handed sneutrinos of mass $\lesssim 4\mathrm{TeV}$. The presence of right-handed neutrinos and sneutrinos triggers the baryon and lepton number violation processes, until they decouple from the standard model particles. Besides, the model predicts rather heavy colored particles; $m_{\tilde{t}}$, $m_{\tilde{b}}\gtrsim 1.5\mathrm{TeV}$, while $m_{\tilde{\tau }}\gtrsim 100\mathrm{GeV}$ and $m_{{\tilde{\chi }}_1^{\pm }}\gtrsim 600\mathrm{GeV}$. Even though the implications are similar to the minimal supersymmetric standard model, BLSSM can predict another Higgs boson lighter than 150 GeV. We find that the second Higgs boson can be degenerate with the lightest charge parity ($CP$)-even Higgs boson of mass about 125 GeV and contribute to the Higgs decay into two photons. In addition, it can provide an explanation for the excess in $h\to 4l$ at the mass scale $\sim 145\mathrm{GeV}$.

Chiral phase transition of two-flavor QCD at finite quark masses is known to be a crossover except near the chiral limit, but it can turn to a first order transition when adding many extra flavors. This property is used to explore the nature of the phase transition of massless two-flavor QCD using lattice numerical simulations. The extra heavy flavors being incorporated in the form of the hopping parameter expansion through the reweighting, the number of the extra flavors and their masses appear only in a single parameter, defined by $h$. We determine the critical value of $h$, at which the first order and the crossover regions are separated, and examine its dependence on the two-flavor mass. The lattice calculations are carried out at $N_t=4$, and show that the critical value of $h$ does not depend on the two-flavor mass in the range we have studied ($0.46\le m_{\pi }/m_{\rho }\le 0.66$) and appears to remain finite and positive in the chiral limit, suggesting that the phase transition of massless two-flavor QCD is of second order.

In this paper we study the relationship between the $D_{s0}^{*}(2317{)}^{+}$ resonance and the decay of the $B_c$ meson into $J/\psi DK$. In this process, the $B_c$ meson decays first into $J/\psi$ and the quark pair $c\overline{s}$, and then the quark pair hadronizes into $DK$ or $D_s\eta$ components, which undergo final state interaction. This final state interaction, generating the $D_{s0}^{*}(2317{)}^{+}$ resonance, is described by the chiral unitary approach. With the parameters which allow us to match the pole position of the $D_{s0}^{*}(2317{)}^{+}$, we obtain the $DK$ invariant mass distribution of the decay $B_c\to J/\psi DK$, and also the rate for $B_c\to J/\psi D_{s0}^{*}(2317)$. The ratio of these two magnitudes is then predicted.

We use a sample of $\text{diphoton}+\text{dijet}$ events to measure the effective cross section of double parton interactions, which characterizes the area containing the interacting partons in proton-antiproton collisions, and find it to be ${\sigma }_{\text{eff}}=19.3\pm 1.4(\text{stat})\pm 7.8(\text{syst})\mathrm{mb}$. The sample was collected by the D0 detector at the Fermilab Tevatron collider in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ and corresponds to an integrated luminosity of $8.7{\mathrm{fb}}^{-1}$.

We use the heat kernel method to calculate the entanglement entropy for a given entangling region on a fractal. The leading divergent term of the entropy is obtained as a function of the fractal dimension as well as the walk dimension. The power of the UV cutoff parameter is (generally) a fractional number, which, indeed, is a certain combination of these two indices. This exponent is known as the spectral dimension. We show that there is a novel log-periodic oscillatory behavior in the expression of entropy which has root in the complex dimension of the fractal. We finally indicate that the holographic calculation in a certain hyperscaling-violating bulk geometry yields the same leading term for the entanglement entropy, if one identifies the effective dimension of the hyperscaling-violating theory with the spectral dimension of the fractal. We provide additional support by comparing the behavior of the thermal entropy in terms of the temperature, computed for two geometries, the fractal geometry and the hyperscaling-violating background.

With the assistance of a complex singlet, and an effective operator involving $CP$ violations, the dark matter relic abundance and baryon asymmetry of the universe have been addressed simultaneously. We studied the electroweak baryogenesis mechanism systematically. The electroweak phase transition analysis indicates that the strong first order phase transition takes place by one-step or two-step type due to the dynamics of the energy gap between the electroweak vacuum and the vacuum of the complex singlet. The relation between the magnitude of baryon asymmetry of the universe and the phase transition type and strength has been explored in the framework of electroweak baryogenesis.

We propose a universal inequality that unifies the Bousso bound with the classical focusing theorem. Given a surface $\sigma$ that need not lie on a horizon, we define a finite generalized entropy $S_{\mathrm{gen}}$ as the area of $\sigma$ in Planck units, plus the von Neumann entropy of its exterior. Given a null congruence $N$ orthogonal to $\sigma$, the rate of change of $S_{\mathrm{gen}}$ per unit area defines a quantum expansion. We conjecture that the quantum expansion cannot increase along $N$. This extends the notion of universal focusing to cases where quantum matter may violate the null energy condition. Integrating the conjecture yields a precise version of the Strominger-Thompson quantum Bousso bound. Applied to locally parallel light-rays, the conjecture implies a novel inequality, the quantum null energy condition, a lower bound on the stress tensor in terms of the second derivative of the von Neumann entropy. We sketch a proof of the latter relation in quantum field theory.

We study the gravitational collapse of a kink within spherical symmetry and the characteristic formulation of general relativity. We explore some expected but elusive gravitational collapse issues which have not been studied before in detail, finding new features. The numerical one-parametric solution and the structure of the spacetime are calculated using finite differences, Galerkin collocation techniques, and some scripting for automated grid coverage. We study the threshold of black hole formation and confirm a mass gap in the phase transition. In the supercritical case we find a mass scaling power law $M_{\mathrm{BH}}=M_{\mathrm{BH}}^{*}+K[\lambda -{\lambda }^{*}{]}^{2\gamma }+f(K[\lambda -{\lambda }^{*}{]}^{2\gamma })$, with $\gamma \approx 0.37$ independent of the initial data for the cases considered, and $M_{\mathrm{BH}}^{*}$, $K$ and ${\lambda }^{*}$ each depending on the initial datum. The spacetime has a self-similar structure with a period of $\mathrm{\Delta }\approx 3.4$. In the subcritical case the Bondi mass at null infinity decays in cascade with $\mathrm{\Delta }/2$ interval as expected.

I provide a frequency domain reduced order model (ROM) for the aligned-spin effective-one-body model “SEOBNRv2” for data analysis with second- and third-generation ground-based gravitational wave (GW) detectors. SEOBNRv2 models the dominant mode of the GWs emitted by the coalescence of black hole binaries. The large physical parameter space (dimensionless spins $-1\le {\chi }_i\le 0.99$ and symmetric mass ratios $0.01\le \eta \le 0.25$) requires sophisticated reduced order modeling techniques, including patching in the parameter space and in frequency. I find that the time window over which the inspiral-plunge and the merger-ringdown waveform in SEOBNRv2 are connected has a discontinuous dependence on the parameters when the spin parameter $\chi =0.8$ or the symmetric mass ratio $\eta \sim 0.083$. This discontinuity increases resolution requirements for the ROM. The ROM can be used for compact binary systems with total masses of $2M_{\odot }$ or higher for the Advanced LIGO design sensitivity and a 10 Hz lower cutoff frequency. The ROM has a worst mismatch against SEOBNRv2 of $\sim 1\%$, but in general mismatches are better than $\sim 0.1\%$. The ROM is crucial for key data analysis applications for compact binaries, such as GW searches and parameter estimation carried out within the LIGO Scientific Collaboration.