The Higgs-boson mass used to be the only unknown input parameter of the electroweak contributions to $(g-2{)}_{\mu }$ in the Standard Model. It enters at the two-loop level in diagrams with, e.g., top loops, $W$, or $Z$ exchange. We reevaluate these contributions, providing analytic expressions and exact numerical results for the Higgs-boson mass recently measured at the LHC. Our final result for the full Standard Model electroweak contributions is $(153.6\pm 1.0)\times {10}^{-11}$, where the remaining theory error comes from unknown three-loop contributions and hadronic uncertainties.

Spin interactions in a relativistic quark-antiquark system in a magnetic field is considered in the framework of the relativistic Hamiltonian, derived from the QCD path integral. The formalism allows us to separate spin-dependent terms from the basic spin-independent interaction contained in the Wilson loop, and produce confining and gluon exchange interaction. As a result, one obtains a relativistic spin-spin interaction $V_{ss}$ generalizing its nonrelativistic analog. It is shown that in a large magnetic field $eB$, $V_{ss}$ modifies and produces hyperfine shifts which grow linearly with $eB$ and preclude the use of perturbation theory. We also show that tensor forces for $eB\ne 0$ are active in all meson states but do not grow with $eB$.

In this paper we discuss decays of the Higgs boson to quarkonia in association with a photon. We identify a new mechanism for producing such final states in Higgs decays that leads to predictions for the decay rates that differ by an order of magnitude from previous estimates. Although the branching ratios for these processes are still small, the processes are experimentally clean, and the $H\to J/\psi \gamma$ decay should be observable at a 14 TeV LHC. We point out that quantum interference between two different production mechanisms makes the decay rates sensitive to the $H\overline{Q}Q$ couplings. Consequently, measurements of the $H\to J/\psi \gamma$ decay rate would allow one to probe the Higgs-charm coupling directly at the LHC. We discuss the experimental prospects for the observation of these decays and for the direct measurement of the $H\overline{c}c$ coupling.

The China Dark Matter Experiment Collaboration reports the first experimental limit on weakly interacting massive particles (WIMPs) dark matter from 14.6 kg-days of data taken with a 994 g p-type point-contact germanium detector at the China Jinping underground laboratory where the rock overburden is more than 2400 m. The energy threshold achieved was 400 eVee. According to the 14.6 kg-day live data, we placed the limit of ${\sigma }_{\chi N}=1.75\times {10}^{-40}{\mathrm{cm}}^2$ at a 90% confidence level on the spin-independent cross section at a WIMP mass of 7 GeV before differentiating bulk signals from the surface backgrounds.

We measure the mass difference, $\Delta m_0$, between the $D^{*}(2010{)}^{+}$ and the $D^0$ and the natural linewidth, $\Gamma$, of the transition $D^{*}(2010{)}^{+}\to D^0{\pi }^{+}$. The data were recorded with the BABAR detector at center-of-mass energies at and near the ${\rm Y}(4S)$ resonance, and correspond to an integrated luminosity of approximately $477{\mathrm{fb}}^{-1}$. The $D^0$ is reconstructed in the decay modes $D^0\to K^{-}{\pi }^{+}$ and $D^0\to K^{-}{\pi }^{+}{\pi }^{-}{\pi }^{+}$. For the decay mode $D^0\to K^{-}{\pi }^{+}$ we obtain $\Gamma =(83.4\pm 1.7\pm 1.5)\mathrm{keV}$ and $\Delta m_0=(145425.6\pm 0.6\pm 1.8)\mathrm{keV}$, where the quoted errors are statistical and systematic, respectively. For the $D^0\to K^{-}{\pi }^{+}{\pi }^{-}{\pi }^{+}$ mode we obtain $\Gamma =(83.2\pm 1.5\pm 2.6)\mathrm{keV}$ and $\Delta m_0=(145426.6\pm 0.5\pm 2.0)\mathrm{keV}$. The combined measurements yield $\Gamma =(83.3\pm 1.2\pm 1.4)\mathrm{keV}$ and $\Delta m_0=(145425.9\pm 0.4\pm 1.7)\mathrm{keV}$; the width is a factor of approximately 12 times more precise than the previous value, while the mass difference is a factor of approximately 6 times more precise.

Gravity duals for little string theories—which give rise to four-dimensional theories that undergo permanent confinement in the infrared—have not been studied in great detail. We address this question in the framework of heterotic $SO(32)$ and $E_8\times E_8$ string theory, constructing these backgrounds by wrapping heterotic 5-branes on calibrated two-cycles of non-Kähler resolved conifolds. Related to deformations of the underlying little string theories, we find numerous analytic solutions preserving $\mathcal{N}=1$ supersymmetry in four dimensions. These theories all have non-Abelian global symmetries that generally arise from both the heterotic vector bundle and from certain orbifold states. In the decoupling limit, we argue that the gravity duals are given by non-Kähler manifolds that have both blown-up two-cycles and three-cycles at the origin. We argue this following certain duality sequences that include M-theory torsional manifolds at an intermediate step, which help us to construct new type ${\mathrm{I}}^{\prime }$ gauge/gravity duality pairs. In the M-theory duality frame, we also elucidate new sequences of flips and flops.

Scalar field theory on the fuzzy two-sphere, represented as a Hermitian matrix model that includes kinetic, mass and quartic interaction terms, is studied. The effective action in the symmetric large-$N$ regime is analyzed using a self-consistent bootstrap method which fixes its form up to sixth order in the eigenvalues and gives a closed expression to all orders in the quadratic invariant of the matrix, valid close to semicircular distributions. Using this action the eigenvalue distribution is calculated for the interacting theory in the appropriate scaling limit and the phase transition from the disordered to the symmetric ordered phase is identified, including nonperturbative effects.

A dual Josephson junction corresponding to a ($2+1$)-dimensional nonsuperconducting layer sandwiched between two ($3+1$)-dimensional dual superconducting regions constitutes a model of localization of a $U(1)$ gauge field within the layer. Monopole tunneling currents flow from one dual superconducting region to another due to a phase difference between the wave functions of the monopole condensate below and above the nonsuperconducting layer when there is an electromagnetic field within the layer. These magnetic currents appear within the ($2+1$)-dimensional layer as a gas of magnetic instanton events and a weak electric charge confinement is expected to take place at very long distances within the layer. In the present work, we consider what happens when one introduces fermions in this physical scenario. Due to the dual Meissner effect featured in the dual superconducting bulk, it is argued that unconfined fermions would be localized within the ($2+1$)-dimensional layer, where their quantum fluctuations radiatively induce a Chern-Simons term, which is known to destroy the electric charge confinement and to promote the confinement of the magnetic instantons.

The second functional derivative of the effective potential of pure fermionic field theories is rewritten in a factorized form, which facilitates the evaluation of the renormalization flow rate of the effective action in the Wetterich equation. It is applied to the local potential approximation in cases when the effective potential depends on scalar composites built from the fermions. The procedure is demonstrated explicitly on the example of the $N_f$-flavor Gross-Neveu model and the one-flavor chiral Nambu–Jona-Lasinio model.

Recently, Almheiri, Marolf, Polchinski, and Sully have suggested a Gedankenexperiment to test black hole complementarity. They claim that the postulates of black hole complementarity are mutually inconsistent and choose to give up the “absence of drama” for an infalling observer. According to them, the black hole is shielded by a firewall no later than Page time. This has generated some controversy. We find that an interesting picture emerges when we take into account objections from the advocates of fuzzballs. We reformulate Almheiri, Marolf, Polchinski, and Sully’s Gedankenexperiment in the decoherence picture of quantum mechanics and find that low energy wave packets interact with the radiation quanta rather violently while high energy wave packets do not. This is consistent with Mathur’s recent proposal of fuzzball complementarity for high energy quanta falling into fuzzballs.

The recently discovered inverse magnetic catalysis around the critical temperature indicates that some important information is missing in our current understanding of conventional chiral dynamics of QCD, which is enhanced by the magnetic field. In this work, we provide a mechanism to explain that the inverse magnetic catalysis around $T_c$ is induced by sphalerons. At high temperatures, sphaleron transitions between distinct classical vacua cause an asymmetry in the chiral number density due to the axial anomaly of QCD. In the presence of a strong magnetic field, the chiral imbalance is enhanced and destroys the pairings between the different chiralities, which naturally lowers the critical temperature of the chiral phase transition for increasing magnetic field. The inverse magnetic catalysis at finite baryon density and the critical end point in the presence of a strong magnetic field is also explored in this work.

We study vacuum states and symmetric fermions in the equivariant dimensional reduction of the Yang-Mills-Dirac theory over the six-dimensional homogeneous space $\mathrm{SU}(3)/\mathrm{U}(1)\times \mathrm{U}(1)$ endowed with a family of SU(3) structures including a nearly Kähler structure. We derive the fixed tree-level scalar potentials of the induced Yang-Mills-Higgs theory and compute the dynamically generated gauge and Higgs boson masses as functions of the metric moduli of the coset space. We find an integrable subsector of the Higgs field theory that is governed by a sine-Gordon–type model whose topological soliton solutions are determined nonperturbatively by the gauge coupling and that tunnel between families of infinitely degenerate vacua. The reduction of the Dirac action for symmetric fermions yields exactly massless chiral fermions containing subsectors that have fixed tree-level Yukawa interactions. We compute dynamical fermion mass matrices explicitly and compare them at different points of the moduli space, some of which support consistent heterotic flux vacua.

Using the duality between color and kinematics, we construct the two- and three-loop amplitudes of half-maximal supergravity with matter multiplets and show that new divergences occur in $D=4$ and $D=5$. In a recent paper, Bossard, Howe and Stelle conjecture the existence of 16-supercharge off-shell harmonic superspaces in order to explain the ultraviolet finiteness of pure half-maximal supergravity with no matter multiplets in $D=4$ at three loops and in $D=5$ at two loops. By assuming the required superspace exists in $D=5$, they argue that no new divergences should occur at two loops even with the addition of Abelian-vector matter multiplets. Up to possible issues with the $SL(2,\mathbb{R})$ global anomaly of the theory, they reach a similar conclusion in $D=4$ for two and three loops. The divergences we find contradict these predictions based on the existence of the desired off-shell superspaces. Furthermore, our $D=4$ results are incompatible with the new divergences being due to the anomaly. We find that the two-loop divergences of half-maximal supergravity are directly controlled by the divergences appearing in ordinary nonsupersymmetric Yang-Mills theory coupled to scalars, explaining why half-maximal supergravity develops new divergences when matter multiplets are added. We also provide a list of one- and two-loop counterterms that should be helpful for constraining any future potential explanations of the observed vanishings of divergences in pure half-maximal supergravity.

We show that in a background of a sufficiently strong magnetic field the electroweak sector of the quantum vacuum exhibits superconducting and, unexpectedly, superfluid properties due to the magnetic-field-induced condensation of, respectively, $W$ and $Z$ bosons. The phase transition to the “tandem” superconductor-superfluid phase—which is weakly sensitive to the Higgs sector of the Standard Model—occurs at the critical magnetic field of ${10}^{20}\mathrm{T}$. The superconductor-superfluid phase of the electroweak vacuum has anisotropic transport properties as both charged and neutral superflows may propagate only along the magnetic field axis. The ground state possesses an unusual “kaleidoscopic” structure made of a hexagonal lattice of superfluid vortices superimposed on a triangular lattice of superconductor vortices.

I present the junction conditions for $F(R)$ theories of gravity and their implications: the generalized Israel conditions and equations. These junction conditions are necessary to construct global models of stars, galaxies, etc., where a vacuum region surrounds a finite body in equilibrium, as well as to describe shells of matter and braneworlds, and they are stricter than in General Relativity in both cases. For the latter case, I obtain the field equations for the energy-momentum tensor on the shell/brane, and they turn out to be, remarkably, the same as in General Relativity. An exceptional case for quadratic $F(R)$, previously overlooked in the literature, is shown to arise, allowing for a discontinuous $R$ and leading to an energy-momentum content on the shell with unexpected properties, such as nonvanishing components normal to the shell and a new term resembling classical dipole distributions. For the former case, they require not only the agreement of the first and second fundamental forms on both sides of the matching hypersurface but also that the scalar curvature $R$ and its first derivative $\nabla R$ agree there too. I argue that, as a consequence, matched solutions in General Relativity are not solutions of $F(R)$ models generically. Several relevant examples are analyzed.

The behavior of merging black holes (including the emitted gravitational waves and the properties of the remnant) can currently be computed only by numerical simulations. This paper introduces ten numerical relativity simulations of binary black holes with equal masses and equal spins aligned or antialigned with the orbital angular momentum. The initial spin magnitudes have $|{\chi }_i|\lesssim 0.95$ and are more concentrated in the aligned direction because of the greater astrophysical interest of this case. We combine these data with five previously reported simulations of the same configuration, but with different spin magnitudes, including the highest spin simulated to date, ${\chi }_i\approx 0.97$. This data set is sufficiently accurate to enable us to offer improved analytic fitting formulas for the final spin and for the energy radiated by gravitational waves as a function of initial spin. The improved fitting formulas can help to improve our understanding of the properties of binary black hole merger remnants and can be used to enhance future approximate waveforms for gravitational wave searches, such as effective-one-body waveforms.

Interactions of gauge-invariant systems are severely constrained by several consistency requirements. One is the preservation of the number of gauge symmetries, another is causal propagation. For lower-spin fields, the emphasis is usually put on gauge invariance that happens to be very selective by itself. We demonstrate with an explicit example, however, that gauge invariance, albeit indispensable for constructing interactions, may not suffice as a consistency condition. The chosen example that exhibits this feature is the theory of a massless spin-$3/2$ field coupled to electromagnetism. We show that this system admits an electromagnetic background in which the spin-$3/2$ gauge field may move faster than light. Requiring causal propagation rules out otherwise allowed gauge-invariant couplings. This emphasizes the importance of causality analysis as an independent test for a system of interacting gauge fields. We comment on the implications of allowing new degrees of freedom and nonlocality in a theory, on higher-derivative gravity and Vasiliev’s higher-spin theories.

The Oppenheimer-Snyder solution models a homogeneous round dust cloud collapsing to a black hole. Inside its event horizon there is a region through which trapped surfaces pass. We try to determine exactly where the boundary of this region meets the center of the cloud. We present explicit examples of the relevant trapped (topological) spheres; they extend into the exterior vacuum region, and are carefully matched at the junction between the cloud and the vacuum.

We study the cosmological implications of a ghost-free nonlinear massive gravity theory with a cosmological constant. We find that the massive terms serve as an effective cosmological constant for a large class of metric spaces with a compatible fiducial metric associated with the massive terms. A specific solution is solved as an example for this model under the Bianchi type I space and a compatible Bianchi type I fiducial metric. A stability analysis indicates that this set of solutions tends to be stable. Nonetheless, the anisotropically expanding solution will, in general, turn unstable when an additional scalar field with negative kinetic energy is introduced.

We consider static, spherically symmetric equilibrium configurations consisting of fermionic dark matter nonminimally coupled to dark energy in the form of a quintessence scalar field. With the scalar field coupling function, the form of which is taken to meet cosmological observations, we estimate the effect of such a nonminimal coupling on the properties of dark matter compact configurations. We show that the masses and sizes of the resulting chameleon dark matter stars are smaller than those of systems with no field present.