We argue that the process $pp\to (\text{jet}\gamma )X$, for which a photon is observed inside a fully reconstructed jet and is treated as part of the jet, offers new probes of the so far little-known fragmentation functions for photons. We present a next-to-leading-order QCD calculation of the cross section for this process in the limit that the jet is relatively narrow. We also investigate the background resulting from the two-photon decay of neutral pions. We present numerical results relevant for possible measurements at the LHC and at RHIC. These suggest that $pp\to (\text{jet}\gamma )X$ should provide clean access to the photon fragmentation functions, provided an efficient suppression of the background is available in experiment.

We report the measurement of muon neutrino charged-current interactions on carbon without pions in the final state at the T2K beam energy using $5.734\times {10}^{20}$ protons on target. For the first time the measurement is reported as a flux-integrated, double-differential cross section in muon kinematic variables ($\cos {\theta }_{\mu }$, $p_{\mu }$), without correcting for events where a pion is produced and then absorbed by final state interactions. Two analyses are performed with different selections, background evaluations and cross-section extraction methods to demonstrate the robustness of the results against biases due to model-dependent assumptions. The measurements compare favorably with recent models which include nucleon-nucleon correlations but, given the present precision, the measurement does not distinguish among the available models. The data also agree with Monte Carlo simulations which use effective parameters that are tuned to external data to describe the nuclear effects. The total cross section in the full phase space is $\sigma =(0.417\pm 0.047(\mathrm{syst})\pm 0.005(\mathrm{stat}))\times {10}^{-38}{\mathrm{cm}}^2{\text{nucleon}}^{-1}$ and the cross section integrated in the region of phase space with largest efficiency and best signal-over-background ratio ($\cos {\theta }_{\mu }>0.6$ and $p_{\mu }>200\mathrm{MeV}$) is $\sigma =(0.202\pm 0.036(\mathrm{syst})\pm 0.003(\mathrm{stat}))\times {10}^{-38}{\mathrm{cm}}^2{\text{nucleon}}^{-1}$.

We derive a formula which applies to conformal field theories on a spatial torus and gives the asymptotic density of states solely in terms of the vacuum energy on a parallel plate geometry. The formula follows immediately from global scale and Lorentz invariance, but to our knowledge has not previously been made explicit. It can also be understood from the fact that log $Z$ on ${\mathbb{T}}^2\times {\mathbb{R}}^{d-1}$ transforms as the absolute value of a nonholomorphic modular form of weight $d-1$, which we show. The results are extended to theories which violate Lorentz invariance and hyperscaling but maintain a scaling symmetry. The formula is checked for the cases of a free scalar, free Maxwell gauge field, and free $\mathcal{N}=4$ super Yang-Mills. The case of a Maxwell gauge field gives Casimir’s original calculation of the electromagnetic force between parallel plates in terms of the entropy of a photon gas.

We study a heavy impurity moving longitudinal with the direction of an external magnetic field in an anomalous chiral medium. Such system would carry a nondissipative current of chiral magnetic effect associated with the anomaly. We show, by generalizing Landau’s criterion for superfluidity, that the “anomalous component” which gives rise to the anomalous transport will not contribute to the drag experienced by an impurity. We argue on a very general basis that those systems with a strong magnetic field would exhibit an interesting transport phenomenon—the motion of the heavy impurity is frictionless, in analogy to the case of a superfluid. We demonstrate and confirm our general results with two complementary examples: weakly coupled chiral fermion gases and strongly interacting chiral liquids.

We consider the continuation of free and interacting scalar field theory to noninteger spacetime dimension $d$. We find that the correlation functions in these theories are necessarily incompatible with unitarity (or with reflection positivity in Euclidean signature). In particular, the theories contain negative-norm states unless $d$ is a positive integer. These negative-norm states can be obtained via the operator product expansion from simple positive-norm operators, and are therefore an integral part of the theory. At the Wilson-Fisher fixed point the nonunitarity leads to the existence of complex anomalous dimensions. We demonstrate that they appear already at leading order in the epsilon expansion.

The Casimir effect is a physical manifestation of zero point energy of quantum vacuum. In a relativistic quantum field theory, Poincaré symmetry of the theory seems, at first sight, to imply that nonzero vacuum energy is inconsistent with translational invariance of the vacuum. In the setting of two uniform boundary plates at rest, quantum fields outside the plates have ($1+2$)-dimensional Poincaré symmetry. Taking a massless scalar field as an example, we have examined the consistency between the Poincaré symmetry and the existence of the vacuum energy. We note that, in quantum theory, symmetries are represented projectively in general and show that the Casimir energy is connected to central charges appearing in the algebra of generators in the projective representations.

We study the nonlinear responses of relativistic chiral matter to the external fields such as the electric field $\mathit{E}$, gradients of temperature and chemical potential, $\mathbf{\nabla }T$ and $\mathbf{\nabla }\mu$. Using the kinetic theory with Berry curvature corrections under the relaxation time approximation, we compute the transport coefficients of possible new electric currents that are forbidden in usual chirally symmetric matter but are allowed in chirally asymmetric matter by parity. In particular, we find a new type of electric current proportional to $\mathbf{\nabla }\mu \times \mathit{E}$ due to the interplay between the effects of the Berry curvature and collisions. We also derive an analog of the “Wiedemann-Franz” law specific for anomalous nonlinear transport in relativistic chiral matter.

In this paper, we discuss the impact of a tiny Lorentz violating $b^{\mu }$ term on the one-dimensional motion of a Dirac particle scattering on a rectangular barrier. We assume the experiment is done in a particular inertial frame, where the components of $b^{\mu }$ are assumed constants. The results show that Lorentz violation modification to the transmission rate depends on the nature of $b^{\mu }$. For a purely time-like $b^{\mu }=(b,\overrightarrow{0})$, the transmission rate and resonant tunneling frequency are essentially unaltered compared with the Lorentz invariant counterparts, though the dispersion relation is slightly modified. For a space-like or light-like $b^{\mu }$, the incoming electron is polarized, and the Lorentz violation induced resonant frequency shift depends on the polarization. In fact, for certain special cases, like $b^{\mu }=b(0,{\overrightarrow{e}}_Z)$ or $b^{\mu }=b(1,{\overrightarrow{e}}_Z)$, the absolute frequency difference between different helicity eigenstates with the same resonant number $n$ is $2b$. In addition to being of theoretical interest in the high energy region, its quantum analogue may be experimentally realizable in other areas of physics, like graphene or optical lattices, and may generate some cross interests in both fields.

The tetrad method is used for an introduction of local Lorentz frames and a detailed analysis of local Lorentz transformations. A formulation of equations of motion in local Lorentz frames is based on the Pomeransky-Khriplovich gravitoelectromagnetic fields. These fields are calculated in the most important special cases and their local Lorentz transformations are determined. The local Lorentz transformations and the Pomeransky-Khriplovich gravitoelectromagnetic fields are applied for a rigorous derivation of a general equation for the Thomas effect in Riemannian spacetimes and for a consideration of Einstein’s equivalence principle and the Mathisson force.

We show that optomechanical systems can test the Schrödinger-Newton equation of gravitational quantum mechanics due to Yang et al. Phys. Rev. Lett. 110, 170401 (2013). This equation is motivated by semiclassical gravity, a widely used theory of interacting gravitational and quantum fields. From the many-body Schrödinger-Newton equation follows an approximate equation for the center-of-mass dynamics of macroscopic objects. This predicts a distinctive double-peaked signature in the output optical quadrature power spectral density of certain optomechanical systems. Since the Schrödinger-Newton equation lacks free parameters, these will allow its experimental confirmation or refutation.

We investigate irregularity factors for a self-gravitating spherical star evolving in the presence of an imperfect fluid. We explore the gravitational field equations and the dynamical equations with the systematic construction in $f(R,T)$ gravity, where $T$ is the trace of the energy-momentum tensor. Furthermore, we analyze two well-known differential equations (which occupy principal importance in the exploration of causes of energy density inhomogeneities) with the help of the Weyl tensor and the conservation laws. The irregularity factors for a spherical star are examined for particular cases of dust and isotropic and anisotropic fluids in dissipative and nondissipative regimes in the framework of $f(R,T)$ gravity. It is found that, as the complexity of the matter with the anisotropic stresses increases, the inhomogeneity factor corresponds more closely to one of the structure scalars.

In this paper, we study the expectation values of the induced charge and current densities for a massive bosonic field with nonzero chemical potential in the geometry of a higher-dimensional compactified cosmic string with magnetic fluxes along the string core and also enclosed by the compactified direction in thermal equilibrium at finite temperature $T$. These densities are calculated by decomposing them into the vacuum expectation values and finite temperature contributions coming from the particles and antiparticles. The only nonzero components correspond to the charge, azimuthal, and axial current densities. By using the Abel-Plana formula, we decompose the components of the densities into the part induced by the cosmic string and the one by the compactification. The charge density is an odd function of the chemical potential and even periodic function of the magnetic flux with a period equal to the quantum flux. Moreover, the azimuthal (axial) current density is an even function of the chemical potential and an odd (even) periodic function of the magnetic flux with the same period. In this paper, our main concern is the thermal effect on the charge and current densities, including some limiting cases, the low- and high-temperature approximations. We show that in all cases, the temperature enhances the induced densities.

High-energy neutrinos (HEN) and gravitational waves (GW) can probe astrophysical sources in addition to electromagnetic observations. Multimessenger studies can reveal the nature of the sources, which may not be discerned from one type of signal alone. We discuss HEN emission in connection with the Advanced Laser Interferometer Gravitational-Wave Observatory event GW150914, which could be associated with a short gamma-ray burst detected by the Fermi Gamma-Ray Burst Monitor 0.4 s after the GW event and within localization uncertainty of the GW event. We calculate HEN flux from this short gamma-ray burst, GW150914-GBM, and show that nondetection of a high-energy starting event by the IceCube Neutrino Observatory can constrain the total isotropic-equivalent jet energy of this short burst to be less than $3\times {10}^{52}\mathrm{erg}$.

We present an archival search for transient gravitational-wave bursts in coincidence with 27 single-pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo, and GEO interferometer network. We also discuss a check for gravitational-wave signals in coincidence with Parkes fast radio bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short-duration radio signals and transient gravitational-wave emission include starquakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational-wave emission in coincidence with these radio transients was found, the current analysis serves as a prototype for similar future searches using more sensitive second-generation interferometers.

If the 750-GeV diphoton excess is identified with the color-singlet isosinglet technipion $P^0$ (750) in the one-family walking technicolor model, as in our previous paper, then there should exist another color-singlet technipion-isotriplet one, $P^{\pm ,3}$, predicted at around 950 GeV independently of the dynamical details. The $P^{\pm ,3}(950)$ are produced at the LHC via vector-boson and photon-fusion processes, predominantly decaying to $W\gamma$ and $\gamma \gamma$, respectively. Those walking technicolor signals can be explored at run 2 or 3, which would further open the door for a plethora of other (colored) technipions.

The lepton flavor violating decay of the Standard Model-like Higgs boson (LFVHD) is discussed in the framework of the radiative neutrino mass model built in [K. Nishiwaki, H. Okada, and Y. Orikasa, Phys. Rev. D 92, 093013 (2015)]. The branching ratio (BR) of the LFVHD is shown to reach ${10}^{-5}$ in the most interesting region of the parameter space shown in [K. Nishiwaki, H. Okada, and Y. Orikasa, Phys. Rev. D 92, 093013 (2015)]. The dominant contributions come from the singly charged Higgs mediations, namely, the coupling of $h_2^{\pm }$ with exotic neutrinos. Furthermore, if the doubly charged Higgs boson is heavy enough to allow the mass of $h_2^{\pm }$ around 1 TeV, the mentioned BR can reach ${10}^{-4}$. In addition, we obtain that the large values of $\mathrm{Br}(h\to \mu \tau )$ lead to very small ones of $\mathrm{Br}(h\to e\tau )$, much smaller than the various sensitivities of current experiments.

We nonperturbatively determine the renormalization factor of the axial vector current in lattice QCD with $N_{\mathrm{f}}=3$ flavors of Wilson-clover fermions and the tree-level Symanzik-improved gauge action. The (by now standard) renormalization condition is derived from the massive axial Ward identity, and it is imposed among Schrödinger functional states with large overlap on the lowest lying hadronic state in the pseudoscalar channel, in order to reduce kinematically enhanced cutoff effects. We explore a range of couplings relevant for simulations at lattice spacings of $\approx 0.09\mathrm{fm}$ and below. An interpolation formula for $Z_{\mathrm{A}}(g_0^2)$, smoothly connecting the nonperturbative values to the 1-loop expression, is provided together with our final results.

We present a lattice QCD determination of the vector and scalar form factors of the semileptonic $K\to \pi \ell \nu$ decay which are relevant for the extraction of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{us}|$ from experimental data. Our results are based on the gauge configurations produced by the European Twisted Mass Collaboration with $N_f=2+1+1$ dynamical fermions, which include in the sea, besides two light mass degenerate quarks, also the strange and the charm quarks. We use data simulated at three different values of the lattice spacing and with pion masses as small as 210 MeV. Our final result for the vector form factor at zero momentum transfer is $f_{+}(0)=0.9709(46)$, where the uncertainty is both statistical and systematic combined in quadrature. Using the latest experimental value of $f_{+}(0)|V_{us}|$ from $K_{\ell 3}$ decays, we obtain $|V_{us}|=0.2230(11)$, which allows us to test the unitarity constraint of the Standard Model below the permille level once the determination of $|V_{ud}|$ from superallowed nuclear $\beta$ decays is adopted. A slight tension with unitarity at the level of $\sim 2$ standard deviations is observed. Moreover, we present our results for the semileptonic scalar $f_0(q^2)$ and vector $f_{+}(q^2)$ form factors in the whole range of values of the squared four-momentum transfer $q^2$ measured in $K_{\ell 3}$ decays, obtaining a very good agreement with the momentum dependence of the experimental data. We provide a set of synthetic data points representing our results for the vector and scalar form factors at the physical point for several selected values of $q^2$.

For particle physics observables at colliders such as the LHC at CERN, it has been common practice for many decades to estimate the theoretical uncertainty by studying the variations of the predicted cross sections with a priori unpredictable scales. In astroparticle physics, this has so far not been possible, since most of the observables were calculated at Born level only, so that the renormalization scheme and scale dependence could not be studied in a meaningful way. In this paper, we present the first quantitative study of the theoretical uncertainty of the neutralino dark matter relic density from scheme and scale variations. We first explain in detail how the renormalization scale enters the tree-level calculations through coupling constants, masses and mixing angles. We then demonstrate a reduction of the renormalization scale dependence through one-loop SUSY-QCD corrections in many different dark matter annihilation channels and enhanced perturbative stability of a mixed on-$\mathrm{shell}/\overline{\mathrm{DR}}$ renormalization scheme over a pure $\overline{\mathrm{DR}}$ scheme in the top-quark sector. In the stop-stop annihilation channel, the Sommerfeld enhancement and its scale dependence are shown to be of particular importance. Finally, the impact of our higher-order SUSY-QCD corrections and their scale uncertainties are studied in three typical scenarios of the phenomenological minimal supersymmetric standard model with eleven parameters (pMSSM-11). We find that the theoretical uncertainty is reduced in many cases and can become comparable to the size of the experimental one in some scenarios.