Recently, much progress has been made on techniques to measure the masses of new particles with partially-invisible decays at a hadron collider. We examine for the first time the realistic application of $M_{T2}$-based measurement methods to a fully hadronic final state from a symmetric two-step decay chain with maximal combinatorial uncertainty. Several problems arise in such an analysis: the $M_{T2}$ variables are powerful but fragile, with shallow edges that are easily washed out or faked by ubiquitous combinatorics background. Traditional methods of both cleaning up the distribution and determining edge position can fail badly. To perform successful mass measurements we introduce several new techniques: the edge-to-bump method of extracting an edge from a distribution by analyzing a distribution of fits rather than a single fit; a very simple yet high-yield method for determining decay chain assignments event-by-event; and a systematic procedure to obtain $M_{T2}$ edge measurements in the presence of heavy combinatorics background, the key element being the parallel use of at least two independent methods of reducing combinatorics background to avoid fake measurements. All of these techniques are developed in a Monte Carlo study of the decay $\tilde{g}\tilde{g}\to 2\tilde{b}+2b\to 4b+2{\chi }_1^0$ and verified in a second blind study with a different spectrum. In both cases, the gluino and sbottom masses are measured to a precision of $\sim 10\%$ with $\mathcal{O}(100{\mathrm{fb}}^{-1})$ at the LHC14 (assuming pessimistic $b$-tag efficiencies).

In light of recent data from direct detection experiments and the Large Hadron Collider, we explore models of dark matter in which an $SU(2{)}_L$ doublet is mixed with a standard model singlet. We impose a thermal history. If the new particles are fermions, this model is already constrained due to null results from XENON100. We comment on remaining regions of parameter space and assess prospects for future discovery. We do the same for the model where the new particles are scalars, which at present is less constrained. Much of the remaining parameter space for both models will be probed by the next generation of direct detection experiments. For the fermion model, DeepCore may also play an important role.

We calculate next-to-leading-order (NLO) corrections to the $B\to \pi$ transition form factors at leading twist in the $k_T$ factorization theorem. Light partons off shell by $k_T^2$ are considered in the quark diagrams, in the effective diagrams for the $B$-meson wave function defined with the effective heavy-quark field, and in the effective diagrams for the pion wave function. It is explicitly demonstrated that the infrared logarithms $\ln k_T^2$ cancel between the above sets of diagrams, as deriving the $k_T$-dependent NLO hard kernel from their difference. The infrared finiteness of the hard kernel confirms the application of the $k_T$ factorization theorem to $B$-meson semileptonic decays. The NLO pion wave function is identical to those constructed from the pion transition and electromagnetic form factors, consistent with its universality. Choosing the renormalization and factorization scales lower than the $B$-meson mass, the NLO corrections are under control: they amount only up to 30% of the form factors at large recoil of the pion, when varying models for the meson wave functions.

We investigate the phase structure of massless three-flavor QCD by extending the Nambu–Jona-Lasinio model to include the effects of confinement and the axial anomaly. We study the interplay between the chiral and diquark condensates induced by the axial anomaly, as well as their relationship with the Polyakov loop, which parameterizes confinement. By minimizing the thermodynamic potential we construct the QCD phase diagram and investigate the possibility of realizing a recently discovered low temperature critical point and an associated BEC-BCS crossover. We also perform a Ginzburg-Landau expansion of the thermodynamic potential, comparing our results to a prior analysis based purely on symmetry considerations, in order to assess the lowest-order effects of the condensate-confinement couplings.

It is shown that the introduction of a suitable function in the higher-dimensional gauge field action may be used in order to achieve gauge bosons localization on a thick brane. The model is constructed upon analogies to the effective coupling of neutral scalar field to electromagnetic field and to the Friedberg-Lee model for hadrons. After that we move forward studying the localization of the Kalb-Ramond field via this procedure.

A quantum-mechanical theory is $\mathcal{P}\mathcal{T}$-symmetric if it is described by a Hamiltonian that commutes with $\mathcal{P}\mathcal{T}$, where the operator $\mathcal{P}$ performs space reflection and the operator $\mathcal{T}$ performs time reversal. A $\mathcal{P}\mathcal{T}$-symmetric Hamiltonian often has a parametric region of unbroken $\mathcal{P}\mathcal{T}$ symmetry in which the energy eigenvalues are all real. There may also be a region of broken $\mathcal{P}\mathcal{T}$ symmetry in which some of the eigenvalues are complex. These regions are separated by a phase transition that has been repeatedly observed in laboratory experiments. This paper focuses on the properties of a $\mathcal{P}\mathcal{T}$-symmetric $ig{\varphi }^3$ quantum field theory. This quantum field theory is the analog of the $\mathcal{P}\mathcal{T}$-symmetric quantum-mechanical theory described by the Hamiltonian $H=p^2+i{x}^3$, whose eigenvalues have been rigorously shown to be all real. This paper compares the renormalization group properties of a conventional Hermitian $g{\varphi }^3$ quantum field theory with those of the $\mathcal{P}\mathcal{T}$-symmetric $ig{\varphi }^3$ quantum field theory. It is shown that while the conventional $g{\varphi }^3$ theory in $d=6$ dimensions is asymptotically free, the $ig{\varphi }^3$ theory is like a $g{\varphi }^4$ theory in $d=4$ dimensions; it is energetically stable, perturbatively renormalizable, and trivial.

We consider a class of Lorentz gauge gravity theories within Riemann-Cartan geometry that admits a topological phase in the gravitational sector. The dynamic content of such theories is determined only by the contortion part of the Lorentz gauge connection. We demonstrate that there is a unique Lagrangian that admits propagating spin-one mode in correspondence with gauge theories of other fundamental interactions. Remarkably, despite the $R^2$ type of the Lagrangian and noncompact structure of the Lorentz gauge group, the model possesses rather a positive-definite Hamiltonian. This has been proved in the lowest order of perturbation theory. This implies further consistent quantization and leads to renormalizable quantum theory. It is assumed that the proposed model describes possible mechanism of emergent Einstein gravity at very early stages of the Universe due to quantum dynamics of contortion.

We give a detailed treatment of the backreaction effects on the Hawking spectrum in the late-time expansion within the semiclassical approach to the Hawking radiation. We find that the boundary value problem defining the action of the modes which are regular at the horizon admits in general the presence of caustics. We show that for radii less that a certain critical value $r_c$ no caustic occurs for all values of the wave number and time and we give a rigorous lower bound on such a critical value. We solve the exact system of nonlinear equations defining the motion, by a rigorously convergent iterative procedure. The first two terms of such an expansion give the $O(\omega /M)$ correction to the Hawking spectrum.

We present a new fully first-order strongly hyperbolic representation of the Baumgarte-Shapiro-Shibata-Nakamura formulation of Einstein’s equations with optional constraint damping terms. We describe the characteristic fields of the system, discuss its hyperbolicity properties, and present two numerical implementations and simulations: one using finite differences, adaptive mesh refinement, and, in particular, binary black holes, and another one using the discontinuous Galerkin method in spherical symmetry. The results of this paper constitute a first step in an effort to combine the robustness of Baumgarte-Shapiro-Shibata-Nakamura evolutions with very high accuracy numerical techniques, such as spectral collocation multidomain or discontinuous Galerkin methods.

The gravitational-wave signature emitted from a merging binary depends on the orientation of an observer relative to the binary. Previous studies suggest that emission along the total initial or total final angular momenta leads to both the strongest and simplest signal from a precessing compact binary. In this paper we describe a concrete counterexample: a binary with $m_1/m_2=4$, $a_1=0.6\widehat{x}=-a_2$, placed in orbit in the $x$, $y$ plane. We extract the gravitational-wave emission along several proposed emission directions, including the initial (Newtonian) orbital angular momentum; the final ($\simeq$ initial) total angular momentum; and the dominant principal axis of $⟨L_{(a}{L}_{b)}{⟩}_M$. Using several diagnostics, we show that the suggested preferred directions are not representative. For example, only for a handful of other directions ($p\lesssim 15\%$) will the gravitational-wave signal have comparable shape to the one extracted along each of these fiducial directions, as measured by a generalized overlap ($>0.95$). We conclude that the information available in just one direction (or mode) does not adequately encode the complexity of orientation-dependent emission for even short signals from merging black-hole binaries. Future investigations of precessing, unequal-mass binaries should carefully explore and model their orientation-dependent emission.

General relativity is a generally covariant, locally Lorentz covariant theory of two transverse, traceless graviton degrees of freedom. According to a theorem of Hojman, Kuchař, and Teitelboim, modifications of general relativity must either introduce new degrees of freedom or violate the principle of local Lorentz covariance. In this paper, we explore modifications of general relativity that retain the same graviton degrees of freedom, and therefore explicitly break Lorentz covariance. Motivated by cosmology, the modifications of interest maintain explicit spatial covariance. In spatially covariant theories of the graviton, the physical Hamiltonian density obeys an analogue of the renormalization group equation which encodes invariance under flow through the space of conformally equivalent spatial metrics. This paper is dedicated to setting up the formalism of our approach and applying it to a realistic class of theories. Forthcoming work will apply the formalism more generally.

We explicitly compare the structure of the renormalized stress-energy tensor of a massless scalar field in a $(1+1)$ curved spacetime as obtained by two different strategies: normal-mode construction of the field operator and one-loop effective action. We pay special attention to where and how the information related to the choice of vacuum state in both formalisms is encoded. By establishing a clear translation map between both procedures, we show that these two potentially different renormalized stress-energy tensors are actually equal, when using vacuum-state choices related by this map. One specific aim of the analysis is to facilitate the comparison of results regarding semiclassical effects in gravitational collapse as obtained within these different formalisms.

We expand previous works on the spherical “top-hat” collapse framework in generalized-Chaplygin-gas-dominated universes. Here we allow the collapse in all energetic components within the system. We analyze the nonlinear stages of collapse for various choices of parameter $\alpha$ of the generalized-Chaplygin-gas model introducing an exact formulation for the so-called effective sound speed, $c_{\mathrm{eff}}^2$. We show that, within the spherical top-hat collapse framework, the growth of the structure becomes faster with increasing values of $\alpha$.

We discuss the bending of light in a recent model for gravity at large distances containing a Rindler-type acceleration proposed by Grumiller [Phys. Rev. Lett. 105, 211303 (2010)]. We consider the static, spherically symmetric metric with cosmological constant $\Lambda$ and Rindler-like term $2ar$ presented in this model, and we use the procedure by Rindler and Ishak [W. Rindler and M. Ishak, Phys. Rev. D 76, 043006 (2007).] to obtain the bending angle of light in this metric. Earlier work on light bending in this model by Carloni, Grumiller, and Preis [Phys. Rev. D 83, 124024 (2011)], using the method normally employed for asymptotically flat space-times, led to a conflicting result (caused by the Rindler-like term in the metric) of a bending angle that increases with the distance of closest approach $r_0$ of the light ray from the centrally concentrated spherically symmetric matter distribution. However, when using the alternative approach for light bending in nonasymptotically flat space-times, we show that the linear Rindler-like term produces a small correction to the general relativistic result that is inversely proportional to $r_0$. This will in turn affect the bounds on Rindler acceleration obtained earlier from light bending and casts doubts on the nature of the linear term $2ar$ in the metric.

We construct a supersymmetric extension of double field theory that realizes the ten-dimensional Majorana-Weyl local supersymmetry. In terms of a stringy differential geometry we proposed earlier, our action consists of five simple terms—two bosonic plus three fermionic—and manifests not only diffeomorphism and one-form gauge symmetry of $B$-field, but also $\mathbf{O}(10,10)$ $T$-duality as well as a direct product of two local Lorentz symmetries, $\mathbf{S}\mathbf{O}(1,9)\times \mathbf{S}\mathbf{O}(9,1)$. A gauge fixing that identifies the double local Lorentz groups reduces our action to the minimal supergravity in ten dimensions.

We investigate the critical curve of the string tension $\sigma (T)$ as a function of temperature in quenched gauge invariant SU(3) lattice gauge theory. We extract $\sigma (T)$ from the color averaged free energy of a static quark-antiquark pair. To compute the free energy, we utilize a pair of gauge invariant Polyakov loop and antiloop correlations and apply the multihit procedure to enhance the signal-to-noise ratio. We find that the string tension departs from the zero temperature ${\sigma }_0$ at $T\simeq 0.5T_c$. We cover the relevant temperature range from $0.5T_c$ up to the confinement temperature $T_c$ using 54 different sets of pure gauge lattice configurations with four temporal extensions (4, 6, 8, 12), different $\beta$, and a spatial volume of ${48}^3$ in lattice units.

We show that colliding vortex beams instead of (approximate) plane waves can lead to a direct measurement of how the overall phase of the plane wave scattering amplitude changes with the scattering angle. Since vortex beams are coherent superpositions of plane waves with different momenta, their scattering amplitude receives contributions from plane wave amplitudes with distinct kinematics. These contributions interfere, leading to the measurement of their phase difference. Although interference exists for any generic wave packet collision, we show that using vortex beams dramatically enhances sensitivity to the phase in comparison with nonvortex beams. Since the overall phase is inaccessible in a plane wave collision, this measurement would be of great importance for a number of topics in hadronic physics, for example, meson production in the resonance region, physics of nucleon resonances, and small angle elastic hadron scattering.

We present a new class of unified $SO(10)$ models where the grand unified theory symmetry breaking down to the standard model gauge group involves just one scale, in contrast to the conventional $SO(10)$ models which require two scales. Further, the models we discuss possess a natural doublet-triplet splitting via the missing partner mechanism without fine-tuning. Such models involve $560+\overline{560}$ pair of heavy Higgs fields along with a set of light fields. The $560+\overline{560}$ are the simplest representations of $SO(10)$ besides the $126+\overline{126}$ which contain an excess of color triplets over $SU(2{)}_L$ doublets. We discuss several possibilities for realizing the missing partner mechanism within these schemes. With the $126+\overline{126}$ multiplets, three viable models are found with additional fields belonging to $\{210+2\times 10+120\}$, $\{45+10+120\}$, or $\{210+16+\overline{16}+10+120\}$. With the $560+\overline{560}$, a unique possibility arises for the missing partner mechanism, with additional $\{2\times 10+320\}$ fields. These models are developed in some detail. It is shown that fully realistic fermion masses can arise in some cases, while others can be made realistic by addition of vectorlike representations. Naturally large neutrino mixing angles, including sizable ${\theta }_{13}$, can emerge in these models. The couplings of the $H_u(H_d)$ Higgs doublets of the minimal supersymmetric standard model which give masses to the up quarks (down quarks and leptons) are not necessarily equal at the grand unification scale and would lead to a new phenomenology at the low-energy scales.

LHC-7 has narrowed down the mass range of the light Higgs boson. This result is consistent with the supergravity unification framework, and the current Higgs boson mass window implies a rather significant loop correction to the tree value, pointing to a relatively heavy scalar sparticle spectrum with universal boundary conditions. It is shown that the largest value of the Higgs boson mass is obtained on the hyperbolic branch of radiative breaking. The implications of light Higgs boson in the broader mass range of 115 GeV to 131 GeV and a narrower range of 123 GeV to 127 GeV are explored in the context of the discovery of supersymmetry at LHC-7 and for the observation of dark matter in direct detection experiments.

We study corrections to the conformal hyperscaling relation in the conformal window of the large $N_f$ QCD by using the ladder Schwinger-Dyson (SD) equation as a concrete dynamical model. From the analytical expression of the solution of the ladder SD equation, we identify the form of the leading mass correction to the hyperscaling relation. We find that the anomalous dimension, when identified through the hyperscaling relation neglecting these corrections, yields a value substantially lower than the one at the fixed point ${\gamma }_m^{*}$ for large mass region. We further study finite-volume effects on the hyperscaling relation, based on the ladder SD equation in a finite space-time with the periodic boundary condition. We find that the finite-volume corrections on the hyperscaling relation are negligible compared with the mass correction. The anomalous dimension, when identified through the finite-size hyperscaling relation neglecting the mass corrections as is often done in the lattice analyses, yields almost the same value as that in the case of the infinite space-time neglecting the mass correction, i.e., a substantially lower value than ${\gamma }_m^{*}$ for large mass. We also apply the finite-volume SD equation to the chiral-symmetry-breaking phase and find that when the theory is close to the critical point such that the dynamically generated mass is much smaller than the explicit breaking mass, the finite-size hyperscaling relation is still operative. We also suggest a concrete form of the modification of the finite-size hyperscaling relation by including the mass correction, which may be useful to analyze the lattice data.