We study the semileptonic decay ${\overline{B}}_s\to K^{*+}{\ell }^{-}{\overline{\nu }}_{\ell }$, which is induced by $b\to u{\ell }^{-}{\overline{\nu }}_{\ell }$ transitions at the quark level. We take into account the standard model (SM) operator from $W$-boson exchange as well as possible extensions from physics beyond the SM. The secondary decay $K^{*+}\to K\pi$ can be used to study a number of angular observables, which are worked out in terms of short-distance Wilson coefficients and hadronic form factors. Our analysis allows for an independent extraction of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ and for the determination of certain ratios of ${\overline{B}}_s\to K^{*}$ form factors. Moreover, a future precision measurement of the forward-backward asymmetry in the ${\overline{B}}_s\to K^{*+}{\ell }^{-}{\overline{\nu }}_{\ell }$ decay can be used to unambiguously verify the left-handed nature of the transition operator as predicted by the SM. We provide numerical estimates for the relevant angular observables and the resulting decay distributions on the basis of available form-factor information from lattice and sum-rule estimates. In addition, we pay particular attention to suitable combinations of angular observables in the decays ${\overline{B}}_s\to K^{*+}(\to K\pi ){\ell }^{-}{\overline{\nu }}_{\ell }$ and $\overline{B}\to K^{*0}(\to K\pi ){\ell }^{+}{\ell }^{-}$, and find that they provide complementary constraints on the relevant $b\to s$ short-distance coefficients. As a by-product, we perform a SM fit on the basis of selected experimental decay rates in both inclusive and exclusive channels, and hadronic input functions. We find $|V_{ub}|=(4.07\pm 0.20)\times {10}^{-3}$.

We present the complete next-to-leading order (NLO) QCD and NLO electroweak (EW) corrections to the $W$-boson pair production associated with a hard jet at the LHC including the spin correlated $W$-boson leptonic decays. The dependence of the leading order (LO) and NLO corrected cross sections on the jet transverse momentum cut is investigated. In dealing with the subsequent resonant $W$-boson decays, we adopt the madspin method where the spin correlation effect is included. We also provide the LO and NLO corrected distributions of the transverse momenta and rapidities of final products. The results show that the NLO EW correction is significant in high transverse momentum region due to the EW Sudakov effect.

This article describes a search for high-mass resonances decaying to a pair of photons using a sample of $20.3{\mathrm{fb}}^{-1}$ of $pp$ collisions at $\sqrt{s}=8\mathrm{TeV}$ recorded with the ATLAS detector at the Large Hadron Collider. The data are found to be in agreement with the Standard Model prediction, and limits are reported in the framework of the Randall-Sundrum model. This theory leads to the prediction of graviton states, the lightest of which could be observed at the Large Hadron Collider. A lower limit of 2.66 (1.41) TeV at 95% confidence level is set on the mass of the lightest graviton for couplings of $k/{\overline{M}}_{\mathrm{Pl}}=0.1$ (0.01).

We analyze and compare the finite-temperature electroweak phase transition properties of classically (non)conformal extensions of the standard model. In the classically conformal scenarios the breaking of the electroweak symmetry is generated radiatively. The models feature new scalars coupled conformally to the Higgs sector as well as new fermions. We uncover the parameter space leading to a first-order phase transition with(out) the Veltman conditions. We also discuss dark (matter) aspects of some of the models and compare with existing literature when appropriate. We observe that to accommodate both, a first order electroweak phase transition, and a phenomenologically viable dark matter candidate requires to go beyond the simplest extensions of the standard model. Furthermore these extensions must all feature new degrees of freedom that are naturally lighter than a TeV and therefore the associated models are testable at the upcoming Large Hadron Collider run two experiments.

The exact expression for the entropy current of a fluid in presence of two dimensional gravitational anomalies is given. To make it compatible with the second law of thermodynamics; i.e. positivity of the entropy production rate of a system (which is considered to be fundamental), we find a bound on the sum of the two response parameters (${\overline{C}}_1$ and ${\overline{C}}_2$), in terms of the trace and diffeomorphism anomaly coefficients ($c_w$ and $c_g$). The precise expression, we obtain here, is ${\overline{C}}_1+{\overline{C}}_2\le 4{\pi }^2{c}_w+8{\pi }^2{c}_g$. Interestingly, when the bound is saturated corresponding to a reversible process, the result reproduces earlier findings obtained by either studying field theory on the cone or using the Israel-Hartle-Hawking boundary condition. Finally, possible physical implications and connections with the existing approaches are addressed.

As confusion with lensing B modes begins to limit experiments that search for primordial B-mode polarization, robust methods for delensing the cosmic microwave background (CMB) polarization sky are becoming increasingly important. We investigate in detail the possibility of delensing the CMB with the cosmic infrared background (CIB), emission from dusty star-forming galaxies that is an excellent tracer of the CMB lensing signal, in order to improve constraints on the tensor-to-scalar ratio $r$. We find that the maps of the CIB, such as current Planck satellite maps at 545 GHz, can be used to remove more than half of the lensing B-mode power. Calculating optimal combinations of different large-scale-structure tracers for delensing, we find that coadding CIB data and external arcminute-resolution CMB lensing reconstruction can lead to significant additional improvements in delensing performance. We investigate whether measurement uncertainty in the CIB power spectra will degrade the delensing performance if no model of the CIB spectra is assumed, and instead the CIB power spectra are marginalized over, when constraining $r$. We find that such uncertainty does not significantly affect B-mode surveys smaller than a few thousand degrees. Even for larger surveys it causes only a moderate reduction in CIB delensing performance, especially if the surveys have high (arcminute) resolution, which allows self calibration of the delensing procedure. Though further work on the impact of foreground residuals is required, our overall conclusions for delensing with current CIB data are optimistic: this delensing method can tighten constraints on $r$ by a factor up to $\approx 2.2$, and by a factor up to $\approx 4$ when combined with external lensing reconstruction for $\approx 3\mu \mathrm{K}$-arcmin noise, without requiring the modeling of CIB properties. CIB delensing is thus a promising method for the upcoming generation of CMB polarization surveys.

We study the phase diagram of the Nambu-Jona-Lasinio model in the external magnetic field within the mean-field approximation, taking into account the inhomogeneous chiral condensate. It is shown that there appears a new type of the chiral condensate, endowed with two features of real kink crystal and dual chiral density wave, in the magnetic field. We also show that there are first order phase transitions between different inhomogeneous phases in the presence of magnetic field.

We propose the use of basis invariants, valid for any choice of charge parity ($\mathcal{CP}$) transformation, as a powerful approach to studying specific models of $\mathcal{CP}$ violation in the presence of discrete family symmetries. We illustrate the virtues of this approach for examples based on $A_4$ and $\mathrm{\Delta }(27)$ family symmetries. For $A_4$, we show how to elegantly obtain several known results in the literature. In $\mathrm{\Delta }(27)$ we use the invariant approach to identify how explicit (rather than spontaneous) $\mathcal{CP}$ violation arises, which is geometrical in nature, i.e. persisting for arbitrary couplings in the Lagrangian.

In this paper we explore extensions of the minimal supersymmetric standard model involving two $SU(2{)}_L$ triplet chiral superfields that share a superpotential Dirac mass, only one of which couples to the Higgs fields. This choice is motivated by recent work using two singlet superfields with the same superpotential requirements. We find that, as in the singlet case, the Higgs mass in the triplet extension can easily be raised to 125 GeV without introducing large fine-tuning. For triplets that carry hypercharge, the regions of least fine-tuning are characterized by small contributions to the $\mathcal{T}$ parameter, and light stop squarks, $m_{{\tilde{t}}_1}\sim 300-450\mathrm{GeV}$; the latter is a result of the $\tan \beta$ dependence of the triplet contribution to the Higgs mass. Despite such light stop masses, these models are viable provided the stop-electroweakino spectrum is sufficiently compressed.

We analyze the effects of jet algorithms on each factorized part of the dijet cross sections in $e^{+}{e}^{-}$ annihilation using the soft-collinear effective theory. The jet function and the soft function with a cone-type jet algorithm and the Sterman-Weinberg jet algorithm are computed to next-to-leading order in ${\alpha }_s$, and are shown to be infrared finite using pure dimensional regularization. The integrated and unintegrated jet functions are presented, and compared with other types of jet functions.

A metric-affine approach is employed to study higher-dimensional modified gravity theories involving different powers and contractions of the Ricci tensor. It is shown that the field equations are always second-order, as opposed to the standard metric approach, where this is only achieved for Lagrangians of the Lovelock type. We point out that this property might have relevant implications for the AdS/CFT correspondence in black hole scenarios. We illustrate these aspects by considering the case of Born-Infeld gravity in $d$ dimensions, where we work out exact solutions for electrovacuum configurations. Our results put forward that black hole singularities in arbitrary dimensions can be cured in a purely classical geometric scenario governed by second-order field equations.

We consider generic rotating axially symmetric “dirty” (surrounded by matter) black holes. Near-horizon circular equatorial orbits are examined in two different cases of near-extremal (small surface gravity $\kappa$) and exactly extremal black holes. This has a number of qualitative distinctions. In the first case, it is shown that such orbits can lie as close to the horizon as one wishes on suitably chosen slices of space-time when $\kappa \to 0$. This generalizes the observation of T. Jacobson [Classical Quantum Gravity 28, 187001 (2011)] made for the Kerr metric. If a black hole is extremal ($\kappa =0$), circular on-horizon orbits are impossible for massive particles but, in general, are possible in its vicinity. The corresponding black hole parameters determine also the rate with which a fine-tuned particle on the noncircular near-horizon orbit asymptotically approaches the horizon. Properties of orbits under discussion are also related to the Bañados-Silk-West effect of high energy collisions near black holes. Impossibility of the on-horizon orbits in question is manifestation of kinematic censorship that forbids infinite energies in collisions.

The “dark photon” ${\gamma }_d$ of a gauged $U(1{)}_d$ can become practically invisible if it primarily decays into light states from a dark sector. We point out that, in such scenarios, the running of the $U(1{)}_d$ “fine structure constant” ${\alpha }_d$, with momentum transfer $q^2$, can be significant and potentially measurable. The ${\gamma }_d$ kinetic mixing parameter ${ϵ}^2$ is also expected to run with $q^2$, through its dependence on ${\alpha }_d$. We show how the combined running of ${ϵ}^2{\alpha }_d$ may provide a probe of the spectrum of dark particles and, for ${\alpha }_d\gtrsim \text{few}\times 0.1$, substantially modify predictions for “beam dump” or other intense source experiments. These features are demonstrated in simple models that contain light dark matter and a scalar that breaks $U(1{)}_d$. We also discuss theoretic considerations, regarding the $U(1{)}_d$ model in the ultraviolet regime, that may suggest the infrared upper bound ${\alpha }_d\lesssim 0.1$.

We analyze the potential dark matter implications of LHC events with missing transverse momentum and a resonance, such as a $Z^{\prime }$, decaying to a pair of jets or leptons. This final state contains significant discovery potential, yet has not yet been examined in detail by the LHC experiments. We introduce models of $Z^{\prime }$ production in association with dark matter particles, propose reconstruction and selection strategies, and estimate the sensitivity of the current LHC data set.

We present new measurements of the scintillation and ionization yields in liquid xenon for low energy electronic (about $3–7{\mathrm{keV}}_{ee}$) and nuclear recoils (about $8–20{\mathrm{keV}}_{nr}$) at different drift fields from $236\mathrm{V}/\mathrm{cm}$ to $3.93\mathrm{kV}/\mathrm{cm}$, using a three-dimensional sensitive liquid xenon time projection chamber with high energy and position resolutions. Our measurement of signal responses to nuclear recoils agrees with predictions from the NEST model. However, our measured ionization (scintillation) yields for electronic recoils are consistently higher (lower) than those from the NEST model by about $5{\mathrm{e}}^{-}/{\mathrm{keV}}_{ee}$ ($\mathrm{ph}/{\mathrm{keV}}_{ee}$) at all scanned drift fields. New recombination parameters based on the Thomas-Imel box model are derived from our data. Given the lack of precise measurement of scintillation and ionization yields for low energy electronic recoils in liquid xenon previously, our new measurement provides so far the best available data covering low energy regions at different drift fields for liquid xenon detectors relevant to dark matter searches.

We use the background-field method and the heat kernel to obtain all counterterms to two-loop order of conformally coupled multiflavor ${\varphi }^3$ theory in six spacetime dimensions, defined in curved spacetime and with spacetime-dependent couplings. We also include spacetime-dependent mass terms for completeness. We use these results to write a general expression for the trace anomaly. With the use of Weyl consistency conditions, we are able to show that the strong $a$-theorem for a certain natural candidate quantity $\tilde{a}$ is violated in this theory and obtain a three-loop expression for the coefficient $a$ of the Euler term in the anomaly.

We investigate the quark-gluon three-point correlation function within a one-loop computation performed in the Curci-Ferrari massive extension of the Faddeev-Popov gauge-fixed action. The mass term is used as a minimal way for taking into account the influence of the Gribov ambiguity. Our results, with renormalization-group improvement, are compared with lattice data. We show that the comparison is, in general, very satisfactory for the functions which are compatible with chiral symmetry, except for one. We argue that this may be due to large systematic errors when extracting this function from lattice simulations. The quantities which break chiral symmetry are more sensitive to the details of the renormalization scheme. We, however, manage to reproduce some of them with good precision. The chosen parameters allow us to simultaneously fit the quark mass function coming from the quark propagator with reasonable agreement.

We investigate the Higgs potential beyond the Planck scale in the superstring theory, under the assumption that the supersymmetry is broken at the string scale. We identify the Higgs field as a massless state of the string, which is indicated by the fact that the bare Higgs mass can be zero around the string scale. We find that, in the large field region, the Higgs potential is connected to a runaway vacuum with vanishing energy, which corresponds to opening up an extra dimension. We verify that such universal behavior indeed follows from the toroidal compactification of the nonsupersymmetric $SO(16)\times SO(16)$ heterotic string theory. We show that this behavior fits in the picture that the Higgs field is the source of the eternal inflation. The observed small value of the cosmological constant of our universe may be understood as the degeneracy with this runaway vacuum, which has vanishing energy, as is suggested by the multiple point criticality principle.

We consider metric-affine scenarios where a modified gravitational action is sourced by electrovacuum fields in a three dimensional space-time. We first study the case of $f(R)$ theories, finding deviations near the center as compared to the solutions of general relativity. We then consider Born-Infeld gravity, which has raised a lot of interest in the last few years regarding its applications in astrophysics and cosmology, and show that new features always arise at a finite distance from the center. Several properties of the resulting space-times, in particular in presence of a cosmological constant term, are discussed.

We examine the concept of black hole thermodynamic volume and its consistency with thermodynamic mass in spacetimes that are not asymptotically flat but instead have anisotropic Lifshitz scaling symmetry. We find that the generalized Smarr relation in anti–de Sitter space—extended to include a pressure-volume term—holds here as well, and that there exists a definition of thermodynamic mass and thermodynamic volume that satisfy both this relation and the first law of thermodynamics. We compare the thermodynamic mass with other known quantities such as Arnowitt-Deser-Misner, Brown-York, and Hollands-Ishibashi-Marolf masses. We also conjecture methods for obtaining a thermodynamic mass where there is ambiguity due to the cosmological constant length scale depending on the horizon radius length scale.