Jet energy scale measurements and their systematic uncertainties are reported for jets measured with the ATLAS detector using proton-proton collision data with a center-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$, corresponding to an integrated luminosity of $3.2{\mathrm{fb}}^{-1}$ collected during 2015 at the LHC. Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells, using the anti-$k_t$ algorithm with radius parameter $R=0.4$. Jets are calibrated with a series of simulation-based corrections and in situ techniques. In situ techniques exploit the transverse momentum balance between a jet and a reference object such as a photon, $Z$ boson, or multijet system for jets with $20<p_{\mathrm{T}}<2000\mathrm{GeV}$ and pseudorapidities of $|\eta |<4.5$, using both data and simulation. An uncertainty in the jet energy scale of less than 1% is found in the central calorimeter region ($|\eta |<1.2$) for jets with $100<p_{\mathrm{T}}<500\mathrm{GeV}$. An uncertainty of about 4.5% is found for low-$p_{\mathrm{T}}$ jets with $p_{\mathrm{T}}=20\mathrm{GeV}$ in the central region, dominated by uncertainties in the corrections for multiple proton-proton interactions. The calibration of forward jets ($|\eta |>0.8$) is derived from dijet $p_{\mathrm{T}}$ balance measurements. For jets of $p_{\mathrm{T}}=80\mathrm{GeV}$, the additional uncertainty for the forward jet calibration reaches its largest value of about 2% in the range $|\eta |>3.5$ and in a narrow slice of $2.2<|\eta |<2.4$.

We investigate the internal structure and the mass-radius relation of neutron stars in a recently proposed scalar-tensor theory dubbed asymmetron in which a massive scalar field undergoes spontaneous scalarization inside neutron stars. We focus on the case where the Compton wavelength is shorter than 10 km, which has not been investigated in the literature. By solving the modified Einstein equations, either purely numerically or by partially using a semianalytic method, we find that not only the weakening of gravity by spontaneous scalarization but also the scalar force affect the internal structure significantly in the massive case. We also find that the maximum mass of neutron stars is larger for certain parameter sets than that in general relativity and reaches $2M_{\odot }$ even if the effect of strange hadrons is taken into account. There is even a range of parameters where the maximum mass of neutron stars largely exceeds the threshold that violates the causality bound in general relativity.

The canonical formulation of higher-order theories of gravity can only be accomplished by introducing additional degrees of freedom, namely, the extrinsic curvature tensor $K_{ij}$. Consequently, to match Cauchy data with the boundary data, terms in addition to the three-space metric $h_{ij}$ must also be fixed at the boundary. While in the Ostrogradsky, Dirac, and Horowitz formalisms the extrinsic curvature tensor is kept fixed at the boundary, a modified Horowitz formalism fixes the Ricci scalar $R$ instead. It has been taken for granted that the Hamiltonian structures corresponding to all of the formalisms with different end-point data are either the same or are canonically equivalent. In the present study, we show that this indeed is true, but only for a class of higher-order theories. However, for more general higher-order theories—e.g., dilatonic coupled Gauss-Bonnet gravity in the presence of a curvature-squared term—the Hamiltonian obtained following the modified Horowitz formalism is found to be different from the others, and is not related under canonical transformation. Further, it has also been demonstrated that only the modified Horowitz’ formalism can produce a viable quantum description of the theory, since it only admits a classical analogue under an appropriate semiclassical approximation. Thus, fixing the Ricci scalar $R$ at the boundary appears to be a fundamental issue for a canonical formulation of higher-order theories of gravity.

We demonstrate analytically and numerically the existence of geodesically complete singularities in quintessence and scalar-tensor quintessence models with scalar field potential of the form $V(\varphi )\sim |\varphi {|}^n$ with $0<n<1$. In the case of quintessence, the singularity which occurs at $\varphi =0$, involves divergence of the third time derivative of the scale factor [Generalized Sudden Future Singularity (GSFS)], and of the second derivative of the scalar field. In the case of scalar-tensor quintessence with the same potential and with a linear minimal coupling ($F(\varphi )=1-\lambda \varphi$), the singularity is stronger and involves divergence of the second derivative of the scale factor [Sudden Future Singularity (SFS)]. We show that the scale factor close to the singularity is of the form $a(t)=a_s+b(t_s-t)+c(t_s-t{)}^2+d(t_s-t{)}^q$ where $a_s$, $b,c,d$ are constants which are obtained from the dynamical equations and $t_s$ is the time of the singularity. In the case of quintessence we find $q=n+2$ (i.e. $2<q<3$), while for the case of scalar-tensor quintessence we have a stronger singularity with $q=n+1$ ($1<q<2$). We verify these analytical results numerically and extend them to the case where a perfect fluid, with a constant equation of state $w=\frac{p}{\rho }$, is present. We find that the strength of the singularity (value of $q$) remains unaffected by the presence of a perfect fluid. The linear and quadratic terms in $(t_s-t)$ that appear in the expansion of the scale factor around $t_s$ are subdominant for the diverging derivatives close to the singularity, but can play an important role in the estimation of the Hubble parameter. Using the analytically derived relations between these terms, we derive relations involving the Hubble parameter close to the singularity, which may be used as observational signatures of such singularities in this class of models. For quintessence with matter fluid, we find that close to the singularity $\dot{H}=\frac{3}{2}{\mathrm{\Omega }}_{0m}(1+z_s{)}^3-3H^2$. These terms should be taken into account when searching for future or past time such singularities, in cosmological data.

All pieces of concrete evidence for phenomena outside the standard model (SM)—neutrino masses and dark matter—are consistent with the existence of new degrees of freedom that interact very weakly, if at all, with those in the SM. We propose that these new degrees of freedom organize themselves into a simple dark sector, a chiral $SU(3)\times SU(2)$ gauge theory with the smallest nontrivial fermion content. Similar to the SM, the dark $SU(2)$ is spontaneously broken while the dark $SU(3)$ confines at low energies. At the renormalizable level, the dark sector contains massless fermions—dark leptons—and stable massive particles—dark protons. We find that dark protons with masses between 10 and 100 TeV satisfy all current cosmological and astrophysical observations concerning dark matter even if dark protons are a symmetric thermal relic. The dark leptons play the role of right-handed neutrinos and allow simple realizations of the seesaw mechanism or the possibility that neutrinos are Dirac fermions. In the latter case, neutrino masses are also parametrically different from charged-fermion masses and the lightest neutrino is predicted to be massless. Since the new “neutrino” and “dark-matter” degrees of freedom interact with one another, these two new-physics phenomena are intertwined. Dark leptons play a nontrivial role in early Universe cosmology while indirect searches for dark matter involve, decisively, dark-matter annihilations into dark leptons. These, in turn, may lead to observable signatures at high-energy neutrino and gamma-ray observatories, especially once one accounts for the potential Sommerfeld enhancement of the annihilation cross section, derived from the low-energy dark-sector effective theory, a possibility we explore quantitatively in some detail.

We show the AdS/CFT correspondence between the conformal partial wave and the geodesic Witten diagram with antisymmetric exchange. To this end, we introduce the embedding space formalism for antisymmetric fields in anti-de Sitter. Then, we prove that the geodesic Witten diagram satisfies the conformal Casimir equation and the appropriate boundary condition. Furthermore, we discuss the connection between the geodesic Witten diagram and the shadow formalism by using the split representation of the harmonic function for antisymmetric fields. We also discuss the three-point geodesic Witten diagrams and its extension to the mixed-symmetric tensors.

We study the simplest superstring bit model at finite $N$ using the characters of the $SU(N)$ group. We obtain exact, analytic expressions for small $N$ partition functions and Gaussian approximations for them in the high-temperature limit for all $N$. We use numerical evidence to identify two temperature regimes where the partition function has different limiting behaviors. The temperature at which this transition takes place is identified as the Hagedorn temperature.

Models of inflationary magnetogenesis with a coupling to the electromagnetic action of the form $f^2{F}_{\mu \nu }{F}^{\mu \nu }$, are known to suffer from several problems. These include the strong coupling problem, the backreaction problem and also strong constraints due to the Schwinger effect. We propose a model which resolves all these issues. In our model, the coupling function, $f$, grows during inflation and transits to a decaying phase post-inflation. This evolutionary behavior is chosen so as to avoid the problem of strong coupling. By assuming a suitable power-law form of the coupling function, we can also neglect backreaction effects during inflation. To avoid backreaction post-inflation, we find that the reheating temperature is restricted to be below $\approx 1.7\times {10}^4\mathrm{GeV}$. The magnetic energy spectrum is predicted to be nonhelical and generically blue. The estimated present day magnetic field strength and the corresponding coherence length taking reheating at the QCD epoch (150 MeV) are $1.4\times {10}^{-12}\mathrm{G}$ and $6.1\times {10}^{-4}\mathrm{Mpc}$, respectively. This is obtained after taking account of nonlinear processing over and above the flux-freezing evolution after reheating. If we consider also the possibility of a nonhelical inverse transfer, as indicated in direct numerical simulations, the coherence length and the magnetic field strength are even larger. In all cases mentioned above, the magnetic fields generated in our models satisfy the $\gamma$-ray bound below a certain reheating temperature.

Axions arise in many theoretical extensions of the Standard Model of particle physics, in particular the “string axiverse.” If the axion masses, $m_a$, and (effective) decay constants, $f_a$, lie in specific ranges, then axions contribute to the cosmological dark matter and dark energy densities. We compute the background cosmological (quasi)observables for models with a large number of axion fields, $n_{\text{ax}}\sim \mathcal{O}(10–100)$, with the masses and decay constants drawn from statistical distributions. This reduces the number of parameters from $2n_{\text{ax}}$ to a small number of “hyperparameters.” We consider a number of distributions, from those motivated purely by statistical considerations to those where the structure is specified according to a class of M-theory models. Using Bayesian methods, we are able to constrain the hyperparameters of the distributions. In some cases, the hyperparameters can be related to string theory, e.g., constraining the number ratio of axions to moduli, or the typical decay constant scale needed to provide the correct relic densities. Our methodology incorporates the use of both random matrix theory and Bayesian networks.

Constraining the dark energy (DE) equation of state, $w_{\mathrm{DE}}$, is one of the primary science goals of ongoing and future cosmological surveys. In practice, with imperfect data and incomplete redshift coverage, this requires making assumptions about the evolution of $w_{\mathrm{DE}}$ with redshift $z$. These assumptions can be manifested in a choice of a specific parametric form, which can potentially bias the outcome, or else one can reconstruct $w_{\mathrm{DE}}(z)$ nonparametrically, by specifying a prior covariance matrix that correlates values of $w_{\mathrm{DE}}$ at different redshifts. In this work, we derive the theoretical prior covariance for the effective DE equation of state predicted by general scalar-tensor theories with second order equations of motion (Horndeski theories). This is achieved by generating a large ensemble of possible scalar-tensor theories using a Monte Carlo methodology, including the application of physical viability conditions. We also separately consider the special subcase of the minimally coupled scalar field, or quintessence. The prior shows a preference for tracking behaviors in the most general case. Given the covariance matrix, theoretical priors on parameters of any specific parametrization of $w_{\mathrm{DE}}(z)$ can also be readily derived by projection.

Compensated isocurvature perturbations (CIPs) are primordial fluctuations that balance baryon and dark-matter isocurvature to leave the total matter density unperturbed. The effects of CIPs on the cosmic microwave background (CMB) anisotropies are similar to those produced by weak lensing of the CMB: smoothing of the power spectrum and generation of non-Gaussian features. Here, an entirely new CIP contribution to the standard estimator for the lensing-potential power spectrum is derived. Planck measurements of the temperature and polarization power spectrum, as well as estimates of CMB lensing, are used to place limits on the variance of the CIP fluctuations on CMB scales, ${\mathrm{\Delta }}_{\mathrm{rms}}^2(R_{\mathrm{CMB}})$. The resulting constraint of ${\mathrm{\Delta }}_{\mathrm{rms}}^2(R_{\mathrm{CMB}})<4.3\times {10}^{-3}$ at 95% confidence level (CL) using this new technique improves on past work by a factor of $\sim 3$. We find that for Planck data our constraints almost reach the sensitivity of the optimal CIP estimator. The method presented here is currently the most sensitive probe of the amplitude of a scale-invariant CIP power spectrum, $A_{\mathrm{CIP}}$, placing an upper limit of $A_{\mathrm{CIP}}<0.017$ at 95% CL. Future measurements of the large-scale CMB lensing-potential power spectrum could probe CIP amplitudes as low as ${\mathrm{\Delta }}_{\mathrm{rms}}^2(R_{\mathrm{CMB}})=8\times {10}^{-5}$ at 95% CL (corresponding to $A_{\mathrm{CIP}}=3.2\times {10}^{-4}$).

T-odd correlations in $Wj$ production at the LHC have been studied recently as a way to measure a phase produced by QCD at NLO by Frederix et al. [T-odd Asymmetry in $\mathrm{W}+\text{jet}$ Events at the LHC, Phys. Rev. Lett. 113, 152001 (2014)]. That study found that the induced asymmetry could be observed with $20{\mathrm{fb}}^{-1}$ of 8 TeV data. These T-odd asymmetries can also be induced by $CP$ violating new physics interfering with the SM at LO. In this paper we study this possibility using effective Lagrangians to describe the new physics. We find that the leading contribution arises at dimension eight, and that it necessarily introduces flavor changing neutral currents as well. We discuss the constraints that can be placed on the flavor structure of the new physics operator from studies of FCNC in kaon and B meson decays and then compare the T-odd correlations in $Wj$ induced by $CP$ violating new physics to those induced by QCD at NLO. We quantify the level at which these couplings can be probed at the LHC, and find that they will not affect a measurement of the NLO QCD phases.

We compute the decay widths for the neutral and singly-charged Higgs bosons in the Georgi-Machacek model into the final states $\gamma \gamma$, $Z\gamma$, and $W\gamma$. These decays are most phenomenologically interesting for the fermiophobic custodial fiveplet states $H_5^0$ and $H_5^{\pm }$ when their masses are below threshold for decays into $WW$, $ZZ$, or $WZ$. We study the allowed branching ratios into these final states using scans over the allowed parameter space, and show how the model can be constrained by LEP searches for a fermiophobic Higgs boson decaying to two photons. The calculation involves evaluating one-loop diagrams in which the loop contains particles with two different masses, some of which do not appear in the existing literature. We give results for these diagrams in a form convenient for numerical implementation using the looptools package.

We study the dihadron fragmentation functions (DiFF) of longitudinally polarized quarks into pion pairs. The quark-jet framework is used to model the sequential hadronization of a polarized quark into hadrons, where the polarization transfer to the remnant quark in each hadron emission step is calculated using the spin density matrix formalism. Using Monte Carlo (MC) simulations of the hadronization process, we find a nonvanishing helicity dependent DiFF, $G_1^{\perp }$, which is also related to the longitudinal jet handedness. A method is developed for extracting the angular moments of this DiFF, which enter the expressions for the azimuthal asymmetries for an electron-positron annihilation process into two pairs of hadrons from back-to-back jets and the dihadron production in semi-inclusive deep inelastic scattering. Finally, we derive explicit integral expressions for DiFFs where only two hadrons are emitted by a quark and use them to validate our MC results for both unpolarized and helicity dependent DiFFs.

The half-BPS boundary conditions preserving $\mathcal{N}=(2,2)$ and $\mathcal{N}=(0,4)$ supersymmetry in 3d $\mathcal{N}=4$ supersymmetric gauge theories are examined. The BPS equations admit decomposition of the bulk supermultiplets into specific boundary supermultiplets of preserved supersymmetry. Nahm-like equations arise in the vector multiplet BPS boundary condition preserving $\mathcal{N}=(0,4)$ supersymmetry, and Robin-type boundary conditions appear for the hypermultiplet coupled to the vector multiplet when $\mathcal{N}=(2,2)$ supersymmetry is preserved. The half-BPS boundary conditions are realized in the brane configurations of type IIB string theory.

The ${\mathbb{RP}}^3$ geon and the Schwarzschild black hole are two black hole spacetimes which differ only behind the event horizon. We show that the thermal Hawking radiation emanating from the two black holes contains nontrivial correlations, that these correlations contain information about their interiors, and demonstrate that a particle detector can recover these correlations. In this manner, a simple particle detector can determine the structure behind the event horizon of an eternal black hole.

We derive the trace and diffeomorphism anomalies of the Schrödinger field minimally coupled to the Newton-Cartan background using Fujikawa’s path integral approach. This approach, in particular, enables us to calculate the one-loop contributions due to all the fields of the Newton-Cartan structure. We determine the coefficients and demonstrate that gravitational anomalies for this theory always arise in odd dimensions. Because of the gauge field contribution of the background, we find that in $2+1$ dimensions, the trace anomaly contains terms which have a form similar to that of the $1+1$ and $3+1$ dimensional relativistic trace anomalies. The term similar to the $1+1$ dimensional relativistic trace anomaly provides a type A contribution on Newton-Cartan backgrounds which satisfy the Frobenius condition, in contrast with the result of Lifshitz spacetimes. As an application, we demonstrate that the coefficient of this term satisfies a c-theorem condition.

The Horndeski Lagrangian brings together all possible interactions between gravity and a scalar field that yield second-order field equations in four-dimensional spacetime. As originally proposed, it only addresses phenomenology without torsion, which is a non-Riemannian feature of geometry. Since torsion can potentially affect interesting phenomena such as gravitational waves and early universe inflation, in this paper we allow torsion to exist and propagate within the Horndeski framework. To achieve this goal, we cast the Horndeski Lagrangian in Cartan’s first-order formalism and introduce wave operators designed to act covariantly on $p$-form fields that carry Lorentz indices. We find that nonminimal couplings and second-order derivatives of the scalar field in the Lagrangian are indeed generic sources of torsion. Metric perturbations couple to the background torsion, and new torsional modes appear. These may be detected via gravitational waves but not through Yang-Mills gauge bosons.

We construct traversable thin-shell wormholes which are asymptotically Ads/dS applying the cut and paste procedure for the case of an acoustic metric created by a relativistic Bose-Einstein condensate. We examine several definitions of the flare-out condition along with the violation or not of the energy conditions for such relativistic geometries. Under reasonable assumptions about the equation of state of the matter located at the shell, we concentrate on the mechanical stability of wormholes under radial perturbation preserving the original spherical symmetry. To do so, we consider linearized perturbations around static solutions. We obtain that dS acoustic wormholes remain stable under radial perturbations as long as they have small radius; such wormholes with finite radius do not violate the strong/null energy condition. Besides, we show that stable Ads wormhole satisfy some of the energy conditions whereas unstable Ads wormhole with large radii violate them.