We propose a method to compute the hadronic vacuum polarization function on the lattice at continuous values of photon momenta bridging between the spacelike and timelike regions. We provide two independent demonstrations to show that this method leads to the desired hadronic vacuum polarization function in Minkowski spacetime. We show with the example of the leading-order QCD correction to the muon anomalous magnetic moment that this approach can provide a valuable alternative method for calculations of physical quantities where the hadronic vacuum polarization function enters.

A recent measurement of the total $D^{*+}$ width, ${\Gamma }_{\mathrm{tot}}(D^{*+})=(83.3\pm 1.3\pm 1.4)\mathrm{keV}$, is shown to be close to earlier predictions based on the single-quark-transition hypothesis. Those predictions are updated using more recent masses and branching fractions to a value of 80.4 keV, with a small uncertainty associated with the radiative branching fractions of $D^{*0}$ and $D^{*+}$. A prediction for the total width of $D_2^{*}(2460)$ and its partial width into $D^{*}\pi$ and $D\pi$ is also updated and found to be in agreement with experiment.

Physics beyond the standard model (SM) can be parametrized with an effective Lagrangian that respects the symmetries of the standard model and contains many operators of dimension six. We consider the subset of these operators that is responsible for flavor diagonal anomalous color magnetic and electric dipole couplings between quarks and gluons. Invariance of these operators under the SM implies that they contribute to Higgs boson production at the LHC, and we study the corresponding constraints that can be placed on them. For the case of the top quark we first review constraints from top-quark pair production and decay, and then compare them to what can be achieved by studying $t\overline{t}h$ production. We also constrain the corresponding couplings for $b$ quarks and light quarks by studying $pp\to b\overline{b}h$ and $pp\to hX$, respectively.

We study the effect of QCD corrections to the $gg\to H\to W^{+}{W}^{-}$ signal-background interference at the LHC for a heavy Higgs boson. We construct a soft-collinear approximation to the next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) corrections for the background process, which is exactly known only at leading order (LO). We estimate its accuracy by constructing and comparing the same approximation to the exact result for the signal process, which is known up to NNLO, and we conclude that we can describe the signal-background interference to better than $\mathcal{O}(10\%)$ accuracy. We show that our result implies that, in practice, a fairly good approximation to higher order QCD corrections to the interference may also be obtained by rescaling the known LO result by a $K$ factor computed using the signal process.

Ten years from now reactor neutrino experiments will attempt to determine which neutrino mass eigenstate is the most massive. In this paper we present the results of more than seven million detailed simulations of such experiments, studying the dependence of the probability of successfully determining the mass hierarchy upon the analysis method, the neutrino mass matrix parameters, reactor flux models, geoneutrinos and, in particular, combinations of baselines. We show that a recently reported spurious dependence of the data analysis upon the high energy tail of the reactor spectrum can be removed by using a weighted Fourier transform. We determine the optimal baselines and corresponding detector locations. For most values of the $CP$-violating, leptonic Dirac phase $\delta$, a degeneracy prevents $\mathrm{NO}\nu \mathrm{A}$ and T2K from determining either $\delta$ or the hierarchy. We determine the confidence with which a reactor experiment can determine the hierarchy, breaking the degeneracy.

Recently, it was suggested that there was some sort of breakdown of quantum field theory in the presence of boundaries, manifesting itself as a torque anomaly. In particular, Fulling et al. used the finite energy-momentum-stress tensor in the presence of a perfectly conducting wedge, calculated many years ago by Deutsch and Candelas, to compute the torque on one of the wedge boundaries, where the latter was cut off by integrating the torque density down to minimum lower radius greater than zero. They observed that this torque is not equal to the negative derivative of the energy obtained by integrating the energy density down to the same minimum radius. This motivated a calculation of the torque and energy in an annular sector obtained by the intersection of the wedge with two coaxial cylinders. In a previous paper we showed that for the analogous scalar case, which also exhibited a torque anomaly in the absence of the cylindrical boundaries, the point-split regulated torque and energy indeed exhibit an anomaly, unless the point splitting is along the axis direction. In any case, because of curvature divergences, no unambiguous finite part can be extracted. However, that ambiguity is linear in the wedge angle; if the condition is imposed that the linear term be removed, so that the energy goes to zero for large angles, the resulting torque and energy are finite, and exhibit no anomaly. In this paper, we demonstrate that the same phenomenon takes place for the electromagnetic field, so there is no torque anomaly present here either. This is a nontrivial generalization, since the anomaly found by Fulling et al. is linear for the Dirichlet scalar case, but nonlinear for the conducting electromagnetic case.

We give a proof of the nonperturbative no hair theorems for a massive 2-form field with 3-form field strength for general stationary axisymmetric and static (anti)–de Sitter or asymptotically flat black hole spacetimes with some suitable geometrical properties. The generalization of this result for higher form fields is discussed. Next, we discuss the perturbative no hair theorems for massive spin-$1/2$ fields for general static backgrounds with electric or magnetic charge. Some generalization of this result for stationary axisymmetric spacetimes are also discussed. All calculations are done in arbitrary spacetime dimensions.

In the present paper we study the oscillations of fast rotating neutron stars with realistic equations of state (EoS) within the Cowling approximation. We derive improved empirical relations for gravitational wave asteroseismology with $f$-modes, and for the first time we consider not only quadrupolar oscillations but also modes with higher spherical order ($l=|m|=3$, 4). After performing a systematic comparison with polytropic EoS, we show that the empirical relations found in this case approximately also hold for realistic EoS. In addition, we show that these relations will not change significantly even if the Cowling approximation is dropped and the full general relativistic case is considered, although the normalization used here (frequencies and damping times in the nonrotating limit) could differ considerably. We also address the inverse problem; i.e., we investigate in detail what kind of observational data are required in order to determine characteristic neutron star parameters. It is shown that masses, radii and rotation rates can be estimated quite accurately using the derived asteroseismology relations. We also compute the instability window for certain models, i.e., the limiting curve in a $T-\Omega$ plane where the secular Chandrasekhar-Friedman-Schutz instability overcomes dissipative effects, and we show that some of the modern realistic EoS will lead to a larger instability window compared to all of the polytropic ones presented so far in the literature. Additionally, we calculate the $r$-mode instability window and compare it with the $f$-mode case. The overall results for the instability window suggest that it is vital to take into account oscillations with $l=3$, 4 when considering gravitational wave asteroseismology using the $f$-mode in rapidly rotating neutron stars, as these modes can become unstable for a much larger range of parameters than pure quadrupolar oscillations.

We report on the measurement of the all-particle cosmic ray energy spectrum with the IceTop air shower array in the energy range from 1.58 PeV to 1.26 EeV. The IceTop air shower array is the surface component of the IceCube Neutrino Observatory at the geographical South Pole. The analysis was performed using only information from IceTop. The data used in this work were taken from June 1, 2010 to May 13, 2011. During that period the IceTop array consisted of 73 stations, compared to 81 in its final configuration. The measured spectrum exhibits a clear deviation from a single power law above the knee around 4 PeV and below 1 EeV. We observe spectral hardening around 18 PeV and steepening around 130 PeV.

Extensions of the standard model Higgs sector involving weak isotriplet scalars are not only benchmark candidates to reconcile observed anomalies of the recently discovered Higgs-like particle, but also exhibit a vast parameter space, for which the lightest Higgs’ phenomenology turns out to be very similar to the standard model one. A generic prediction of this model class is the appearance of exotic doubly charged scalar particles. In this paper we adapt existing $\mathrm{\text{dilepton}}+\mathrm{\text{missing energy}}+\mathrm{\text{jets}}$ measurements in the context of supersymmetry searches to the dominant decay mode $H^{\pm \pm }\to W^{\pm }{W}^{\pm }$ and find that the LHC already starts probing the model’s parameter space. A simple modification toward signatures typical of weak boson fusion searches allows us to formulate even tighter constraints with the 7 TeV LHC data set. A corresponding analysis of this channel performed at 14 TeV center-of-mass energy will constrain the model over the entire parameter space and facilitate potential $H^{\pm \pm }\to W^{\pm }{W}^{\pm }$ discoveries.

The quark quasiparticle model is extended to study the properties of color-flavor locked strange quark matter at finite chemical potential and in a strong magnetic field. We present a self-consistent thermodynamic treatment by employing a chemical potential dependent bag function. It is found that the magnetized color-flavor locked (MCFL) matter is more stable than other phases within a proper magnitude of magnetic field. The stability window is graphically shown for the MCFL matter compared with ordinate magnetized matter. The anisotropic structure of MCFL matter is dominated by the magnetic field and almost independent of the energy gaps. A critical maximum magnetic field of about $1.56\times {10}^{18}\mathrm{G}$ is found, under which MCFL matter is absolutely stable with respect to nuclear matter.

The absence so far of any supersymmetric signals at the LHC pushes towards a rethinking of the assumptions underlying the minimal supersymmetric Standard Model. Because the large missing $E_T$ searches are inadequate to detect a lightest supersymmetric partner (LSP) decaying within the detector, $R$-parity violating supersymmetry is still a good candidate for low-energy, natural supersymmetry. We show that, in Froggatt-Nielsen-like models of horizontal symmetries, specific textures for the $R$-parity violating couplings are dictated by the symmetry, with the largest coupling involving the third generation fields. Lepton number can be an accidental symmetry of the renormalizable superpotential and baryon number violation is given by a $\overline{u}\overline{d}\overline{d}$ operator. The collider phenomenology then mimics the main features of minimal flavor violation $R$-parity violating supersymmetry. The LSP can evade current LHC supersymmetry searches and is allowed to be well below 1 TeV, and at the same time all the constraints from proton decay and other low-energy decays can be satisfied; in particular, dimension-five operators allowed by $R$-parity but dangerous for the proton are under control, while neutrino masses are generated by the Weinberg operator. Assuming sub-TeV (natural) superpartners, we obtain both upper and lower limits on the magnitude of the dominant $R$-parity violating coupling: a lower limit of order ${10}^{-9}$ arises from null LHC searches on $R$-hadrons and heavy stable charged particles, while an upper limit of order ${10}^{-2}$ follows from constraints on low-energy flavor-changing neutral currents. Displaced vertices are predicted in the lower end of this range.

Recent studies of the dynamically assisted Schwinger effect have shown that particle production is significantly enhanced by a proper choice of the electric field. We demonstrate that optimal control theory provides a systematic means of modifying the pulse shape in order to maximize the particle yield. We employ the quantum kinetic framework and derive the relevant optimal control equations. By means of simple examples we discuss several important issues of the optimization procedure such as constraints, initial conditions or scaling. By relating our findings to established results we demonstrate that the particle yield is systematically maximized by this procedure.

We study the consequences of dissipation in homogeneous media when the system is subject to a sudden change, thereby producing pairs of correlated quasiparticles with opposite momenta. We compute both the modifications of the spectrum and those of the correlations. In particular, we compute the final coherence level and identify the regimes where the state is nonseparable. To isolate the role of dissipation, we first consider dispersive media and study the competition between the intensity of the jump which induces some coherence, and the temperature which reduces it. The contributions of stimulated and spontaneous emission are clearly identified. We then study how dissipation modifies this competition.

We study the semiclassical behavior of the Lorentzian Engle-Pereira-Rovelli-Livine spinfoam model by taking into account the sum over spins in the large spin regime. The large spin parameter $\lambda$ and small Barbero-Immirzi parameter $\gamma$ are treated as two independent parameters for the asymptotic expansion of the spinfoam state sum [such an idea was first pointed out in E. Magliaro and C. Perini, Europhys. Lett. 95, 30007 (2011); E. MagliaroC. PeriniInt. J. Mod. Phys. D 22, 1350001 (2013)]. Interestingly, there are two different spin regimes: $1\ll {\gamma }^{-1}\ll \lambda \ll {\gamma }^{-2}$ and $\lambda \ge {\gamma }^{-2}$. The models in the two spin regimes have dramatically different numbers of effective degrees of freedom. In $1\ll {\gamma }^{-1}\ll \lambda \ll {\gamma }^{-2}$, the model produces, in the leading order, a functional integration of the Regge action, which gives the discrete Einstein equation for the leading contribution. There is no restriction on the Lorentzian deficit angle in this regime. In the other regime, $\lambda \ge {\gamma }^{-2}$, only a small deficit angle is allowed, $|{\Theta }_f|\ll {\gamma }^{-1}{\lambda }^{-1/2}\mathrm{mod}4\pi \mathbb{Z}$. When spins become even larger, only a zero deficit angle $\mathrm{mod}4\pi \mathbb{Z}$ is allowed asymptotically. In the transition of the two regimes, only the configurations with a small deficit angle can contribute, which means one needs a large triangulation in order to have oscillatory behavior of the spinfoam amplitude.

We consider the possibility that some primordial fields decay purely into the dark sector creating asymmetric dark matter. This asymmetry is subsequently transmuted into leptons and baryons. Within this paradigm we compute the amount of asymmetric dark matter created from the out of equilibrium decays of the primordial fields with $CP$ violating Yukawa couplings. The dark matter asymmetry is then transferred to the visible sector by the asymmetry transfer equation and generates an excess of $B-L$. Baryogenesis occurs via sphaleron processes which conserve $B-L$ but violate $B+L$. A mechanism for the annihilation of the symmetric component of dark matter is also discussed. The model leads to multicomponent dark matter consisting of both bosonic and fermionic components.

In $e^{+}{e}^{-}$ event shapes studies at LEP, two different measurements were sometimes performed: a “calorimetric” measurement using both charged and neutral particles and a “track-based” measurement using just charged particles. Whereas calorimetric measurements are infrared and collinear safe, and therefore calculable in perturbative QCD, track-based measurements necessarily depend on nonperturbative hadronization effects. On the other hand, track-based measurements typically have smaller experimental uncertainties. In this paper, we present the first calculation of the event shape “track thrust” and compare to measurements performed at ALEPH and DELPHI. This calculation is made possible through the recently developed formalism of track functions, which are nonperturbative objects describing how energetic partons fragment into charged hadrons. By incorporating track functions into soft-collinear effective theory, we calculate the distribution for track thrust with next-to-leading logarithmic resummation. Due to a partial cancellation between nonperturbative parameters, the distributions for calorimeter thrust and track thrust are remarkably similar, a feature also seen in LEP data.

We show that the generalized parton distribution functions (GPDFs) in the “skewed” $x\approx \xi \ll 1$ regime can be related in a particularly simple way to the usual diagonal distributions. This follows directly from the Shuvaev transform but bypasses a direct evaluation of the poorly convergent double integral which this relation contains, thus allowing for a more transparent understanding of the physics involved; it avoids the necessity for any further low-$x$ approximations for the diagonal partons as well as permits a clearer application to cases when the GPDFs unintegrated over the parton transverse momentum are required. We consider for illustration the specific examples of the central exclusive production of a standard model Higgs boson, and the photoproduction of $J/\psi$ and ${\rm Y}$ mesons at the LHC, and show how a careful evaluation of the GPDFs, which our simple results allow, is required to correctly calculate the predicted cross sections.

The Standard Model Higgs boson may be mixed with another scalar that does not couple to fermions. The electroweak quantum numbers of such an additional scalar can be determined by measuring the quartic Higgs-Higgs-vector-vector couplings, which contribute—along with the coveted triple Higgs coupling—to double Higgs production in $e^{+}{e}^{-}$ collisions. We show that simultaneous sensitivity to the quartic Higgs-Higgs-vector-vector coupling and the triple Higgs coupling can be obtained using measurements of the double Higgs production cross section at two different $e^{+}{e}^{-}$ center-of-mass energies. Kinematic distributions of the two Higgs bosons in the final state could provide additional discriminating power.