Several modes of $B$ decays into three pseudoscalar octet mesons $PPP$ are measured. These decays provide useful information for $B$ decays in the standard model (SM). Some powerful tools in analyzing $B$ decays are flavor $SU(3)$ and isospin symmetries. Such analyses are usually hampered by $SU(3)$ breaking effects due to a relatively large strange quark mass which breaks $SU(3)$ symmetry down to isospin symmetry. The isospin symmetry also breaks down when the up and down quark mass difference is nonzero. It is, therefore, interesting to find relations which are not sensitive to $SU(3)$ and isospin breaking effects. We find that the relations among several fully symmetric $B\to PPP$ decay amplitudes are not affected by first-order $SU(3)$ breaking effects due to a nonzero strange quark mass, and also some of them are not affected by first isospin breaking effects. These relations, therefore, hold to good precisions. The measurements for these relations can provide important information about $B$ decays in the SM.

We calculate the two-photon exchange corrections to electron-proton scattering with nucleon and $\mathrm{\Delta }$ intermediate states. The results show a dependence on the elastic nucleon and nucleon-$\mathrm{\Delta }$-transition form factors used as input which leads to significant changes compared to previous calculations. We discuss the relevance of these corrections and apply them to the most recent and precise data set and world data from electron-proton scattering. Using this, we show how the form factor extraction from these data is influenced by the subsequent inclusion of physical constraints. The determination of the proton charge radius from scattering data is shown to be dominated by the enforcement of a realistic spectral function. Additionally, the third Zemach moment from the resulting form factors is calculated. The obtained radius and Zemach moment are shown to be consistent with Lamb shift measurements in muonic hydrogen.

For a special value of the mass, a massive graviton on de Sitter space acquires an enhanced scalar gauge symmetry, and is called partially massless. The partially massless graviton possesses a duality invariance akin to electromagnetic duality. We display this duality in its manifestly local and covariant form, in which it acts to interchange the first-order field equations and Bianchi identities of a gauge invariant field strength.

We propose the first covariant local action describing the propagation of a single free continuous-spin degree of freedom. The theory is simply formulated as a gauge theory in a “vector superspace,” but can also be formulated in terms of a tower of symmetric tensor gauge fields. When the spin invariant $\rho$ vanishes, the helicity correspondence is manifest—familiar gauge theory actions are recovered and couplings to conserved currents can easily be introduced. For nonzero $\rho$, a tower of tensor currents must be present, of which only the lowest rank is exactly conserved. A paucity of local gauge-invariant operators for nonzero $\rho$ suggests that the equations of motion in any interacting theory should be covariant, not invariant, under a generalization of the free theory’s gauge symmetry.

We study, within the Nambu-Goto approximation, the stability of massive string junctions under the influence of the tensions of three strings joining together in a Y-type configuration. The relative angle $\beta$ between the strings at the junction is in general time dependent and its evolution can lead to zipping or unzipping of the three-string configuration. We find that these configurations are stable under deformations of the tension balance condition at the junction. The angle $\beta$ relaxes at its equilibrium value and the junction grows relativistically. We then discuss other potential “unzipping agents” including monopole/string forces for long strings and curvature for loops, and we investigate specific solutions exhibiting decelerated zipping and unzipping of the Y junction. These results provide motivation for incorporating the effects of realistic string interactions in network evolution models with string junctions.

On-shell Pauli-Villars regularization of the one-loop divergences of supergravity theories is used to study the anomaly structure of supergravity and the cancellation of field theory anomalies under a $U(1)$ gauge transformation and under the $T$-duality group of modular transformations in effective supergravity theories with three Kähler moduli $T^i$ obtained from orbifold compactification of the weakly coupled heterotic string. This procedure requires constraints on the chiral matter representations of the gauge group that are consistent with known results from orbifold compactifications. Pauli-Villars (PV) regulator fields allow for the cancellation of all quadratic and logarithmic divergences, as well as most linear divergences. If all linear divergences were canceled, the theory would be anomaly free, with noninvariance of the action arising only from Pauli-Villars masses. However there are linear divergences associated with nonrenormalizable gravitino/gaugino interactions that cannot be canceled by PV fields. The resulting chiral anomaly forms a supermultiplet with the corresponding conformal anomaly, provided the ultraviolet cutoff has the appropriate field dependence, in which case total derivative terms, such as Gauss-Bonnet, do not drop out from the effective action. The anomalies can be partially canceled by the four-dimensional version of the Green-Schwarz mechanism, but additional counterterms, and/or a more elaborate set of Pauli-Villars fields and couplings, are needed to cancel the full anomaly, including $D$-term contributions to the conformal anomaly that are nonlinear in the parameters of the anomalous transformations.

Certain aspects of nonrelativistic diffeomorphisms in $2+1$ dimensions are investigated. These include a nonrelativistic limit of some relativistic actions in three dimensions, the Seiberg–Witten map, a modification of the viscosity tensor in particular due to a nonuniform magnetic field, a redefinition of background fields, and $1/R$ terms on Riemann surfaces of constant curvature.

In this paper we evolve magnetized and unmagnetized circumbinary accretion disks around supermassive black hole binaries in the relativistic regime. We use a post-Newtonian expansion to construct an analytical spacetime and determine how the order of the post-Newtonian (PN) expansion affects the dynamics of the gas. We find very small differences in the late-time bulk dynamics of nonmagnetized hydrodynamic evolutions between the two spacetimes down to separations of approximately $40\mathit{GM}/c^2$ where $M$ is the total mass of the binary. For smaller separations, the differences due to PN order become comparable to differences caused by using initial data further from equilibrium. For magnetized gas, magnetohydrodynamic stresses, which drives the accretion dynamics, tends to mask all higher order PN effects even at separations of $20\mathit{GM}/c^2$, leading to essentially the same observed electromagnetic luminosity. This implies that our calculations of the electromagnetic signal may be robust down to small binary separations. Our investigation is the first to demonstrate how the level of PN accuracy affects a circumbinary disk’s evolution and informs us of the range in separation within which to trust the PN approximation for this kind of study. We also address the influence the initial conditions and binary separation have on simulation predictions.

We calculate quasiequilibrium sequences of equal-mass, irrotational binary neutron stars in a scalar-tensor theory of gravity that admits dynamical scalarization. We model neutron stars with realistic equations of state (notably through piecewise polytropic equations of state). Using these quasiequilibrium sequences we compute the binary’s scalar charge and binding energy versus orbital angular frequency. We find that the absolute value of the binding energy is smaller than in general relativity, differing at most by $\sim 14\%$ at high frequencies for the cases considered. We use the newly computed binding energy and the balance equation to estimate the number of gravitational-wave (GW) cycles during the adiabatic, quasicircular inspiral stage up to the end of the sequence, which is the last stable orbit or the mass-shedding point, depending on which comes first. We find that, depending on the scalar-tensor parameters, the number of GW cycles can be substantially smaller than in general relativity. In particular, we obtain that when dynamical scalarization sets in around a GW frequency of $\sim 130\mathrm{Hz}$, the sole inclusion of the scalar-tensor binding energy causes a reduction of GW cycles from $\sim 120\mathrm{Hz}$ up to the end of the sequence ($\sim 1200\mathrm{Hz}$) of $\sim 11\%$ with respect to the general-relativity case. (The number of GW cycles from $\sim 120\mathrm{Hz}$ to the end of the sequence in general relativity is $\sim 270$.) We estimate that when the scalar-tensor energy flux is also included the reduction in GW cycles becomes of $\sim 24\%$. Quite interestingly, dynamical scalarization can produce a difference in the number of GW cycles with respect to the general-relativity point-particle case that is much larger than the effect due to tidal interactions, which is on the order of only a few GW cycles. These results further clarify and confirm recent studies that have evolved binary neutron stars either in full numerical relativity or in post-Newtonian theory, and point out the importance of developing accurate scalar-tensor-theory waveforms for systems composed of strongly self-gravitating objects, such as binary neutron stars.

We extend the gravitational self-force approach to encompass “self-interaction” tidal effects for a compact body of mass $\mu$ on a quasicircular orbit around a black hole of mass $M\gg \mu$. Specifically, we define and calculate at $O(\mu )$ (conservative) shifts in the eigenvalues of the electric- and magnetic-type tidal tensors, and a (dissipative) shift in a scalar product between their eigenbases. This approach yields four gauge-invariant functions, from which one may construct other tidal quantities such as the curvature scalars and the speciality index. First, we analyze the general case of a geodesic in a regular perturbed vacuum spacetime admitting a helical Killing vector and a reflection symmetry. Next, we specialize to focus on circular orbits in the equatorial plane of Kerr spacetime at $O(\mu )$. We present accurate numerical results for the Schwarzschild case for orbital radii up to the light ring, calculated via independent implementations in Lorenz and Regge-Wheeler gauges. We show that our results are consistent with leading-order post-Newtonian expansions, and demonstrate the existence of additional structure in the strong-field regime. We anticipate that our strong-field results will inform (e.g.) effective one-body models for the gravitational two-body problem that are invaluable in the ongoing search for gravitational waves.

We estimate the loss angles of the materials currently used in the highly reflective test-mass coatings of interferometric detectors of gravitational waves, namely Silica, Tantala, and Ti-doped Tantala, from direct measurement of coating thermal noise in an optical interferometer testbench, the Caltech TNI. We also present a simple predictive theory for the material properties of amorphous glassy oxide mixtures, which gives results in good agreement with our measurements on Ti-doped Tantala. Alternative measurement methods and results are reviewed, and some critical issues are discussed.

We propose a class of left-right symmetric models (LRSMs) with spontaneous $D$-parity breaking, where $SU(2{)}_R$ breaks at the TeV scale while discrete left-right symmetry breaks around $10^9\mathrm{GeV}$. By embedding this framework in a nonsupersymmetric $SO(10)$ grand unified theory (GUT) with Pati-Salam symmetry as the highest intermediate breaking step, we obtain $g_R/g_L\approx 0.6$ between the right- and left-handed gauge couplings at the TeV scale. This leads to a suppression of beyond the Standard Model phenomena induced by the right-handed gauge coupling. Here we focus specifically on the consequences for neutrinoless double beta decay, low-energy lepton flavor violation, and LHC signatures due to the suppressed right handed currents. Interestingly, the reduced $g_R$ allows us to interpret an excess of events observed recently in the range of 1.9 to 2.4 TeV by the CMS group at the LHC as the signature of a right-handed gauge boson in LRSMs with spontaneous $D$-parity breaking. Moreover, the reduced right-handed gauge coupling also strongly suppresses the nonstandard contribution of heavy states to the neutrinoless double beta decay rate as well as the amplitude of low-energy lepton flavor violating processes. In a dominant type-II seesaw mechanism of neutrino mass generation, we find that both sets of observables provide stringent and complimentary bounds which make it challenging to observe the scenario at the LHC.

The weak decay of the kaon to two pions is studied within the model of Nambu and Jona-Lasinio. Using the standard effective weak Hamiltonian, both the decay amplitude arising from an intermediate state $\sigma$ meson and the direct decay amplitude are calculated. The effect of final state interactions is also included. When the matching scale is chosen such that the decay amplitude with isospin $I=2$ is close to its experimental value, our model including the $\sigma$ meson contributes up to 80% of the total $I=0$ amplitude. This supports recent suggestions that the $\sigma$ meson should play a vital role in explaining the $\mathrm{\Delta }I=1/2$ rule in this system.

We study the dijet production in the Randall–Sundrum model at the LHC with QCD next-to-leading (NLO) order accuracy. Our results show that the QCD NLO corrections can increase the total cross sections by more than 80% and reduce the scale dependence. We also explore in detail several important kinematic distributions at the NLO level. Moreover, we discuss the upper limits of the Klauza-Klein graviton excluded mass range and the allowed parameter space for the coupling constant and Klauza-Klein graviton mass, using the experiment data.

Multiple scattering leads to transverse momentum broadening of the struck quark in semi-inclusive deeply inelastic scatterings. Nuclear broadening of the transverse momentum squared at the leading twist is determined by the twist-four collinear quark-gluon correlation function of the target nucleus that is in turn related to the jet transport parameter inside the nuclear medium. The twist-six contributions to the transverse momentum broadening are calculated as power corrections $\sim 1/Q^2$. Such power corrections are found to have no extra nuclear enhancement beyond the twist-four matrix elements and are determined by the nuclear modification of collinear parton distribution and correlation functions. They become important for an accurate extraction of the jet transport parameter inside large nuclei and its scale evolution at intermediate values of the hard scale $Q^2$.

In this paper we study the ultraviolet and infrared behavior of the self-energy of a pointlike charge in the vector and scalar Lee-Wick electrodynamics in a $d+1$ dimensional space time. It is shown that in the vector case, the self-energy is strictly ultraviolet finite up to $d=3$ spatial dimensions, finite in the renormalized sense for any $d$ odd, infrared divergent for $d=2$, and ultraviolet divergent for $d>2$ even. On the other hand, in the scalar case, the self-energy is striclty finite for $d\le 3$, and finite, in the renormalized sense, for any $d$ odd.

We revisit the well-studied D0-D4 system of D-branes and its relationship to the Atiyah-Drinfeld-Hitchin-Manin (ADHM) construction. It is well known that the D0-branes appear as instantons in the D4-brane worldvolume. We add a Wilson line to the D4-brane in the guise of an extended fundamental string and determine how this affects the D0-brane dynamics. As the D0-brane moves in the presence of the Wilson line, it experiences a Lorentz force, proportional to its Yang-Mills gauge connection. From the perspective of the D0-brane quantum mechanics, this force emerges through the ADHM construction of the self-dual gauge connection.

Axions and similar very weakly interacting particles are increasingly compelling candidates for the cold dark matter of the Universe. Having very low mass and being produced nonthermally in the early universe, axions feature extremely high occupation numbers. It has been suggested that this leads to the formation of a Bose-Einstein condensate with potentially significant impact on observation and direct detection experiments. In this paper we aim to clarify that if Bose-Einstein condensation occurs for light and very weakly interacting dark matter particles, it does not happen in thermal equilibrium but is described by a far from equilibrium state. In particular we point out that the dynamics is characterized by two very different time scales, such that condensation occurs on a much shorter time scale than full thermalization.

Secret interactions among sterile neutrinos have been recently proposed as an escape route to reconcile eV sterile neutrino hints from short-baseline anomalies with cosmological observations. In particular models with coupling $g_X\gtrsim 10^{-2}$ and gauge boson mediators $X$ with $M_X\lesssim 10\mathrm{MeV}$ lead to large matter potential suppressing the sterile neutrino production before the neutrino decoupling. With this choice of parameter ranges, big-bang nucleosynthesis is left unchanged and gives no bound on the model. However, we show that at lower temperatures when active-sterile oscillations are no longer matter suppressed, sterile neutrinos are still in a collisional regime, due to their secret self-interactions. The interplay between vacuum oscillations and collisions leads to a scattering-induced decoherent production of sterile neutrinos with a fast rate. This process is responsible for a flavor equilibration among the different neutrino species. We explore the effect of this large sterile neutrino population on cosmological observables. We find that a signature of strong secret interactions would be a reduction of the effective number of neutrinos $N_{\text{eff}}$ at matter radiation equality down to 2.7. Moreover, for $M_X\gtrsim g_X\mathrm{MeV}$ sterile neutrinos would be free-streaming before becoming nonrelativistic and they would affect the large-scale structure power spectrum. As a consequence, for this range of parameters we find a tension of an eV mass sterile state with cosmological neutrino mass bounds.

We present a class of charged black hole solutions in an ($n+2$)-dimensional massive gravity with a negative cosmological constant, and study the thermodynamics and phase structure of the black hole solutions in both the grand canonical and canonical ensembles. The black hole horizon can have a positive, zero, or negative constant curvature characterized by the constant $k$. By using the Hamiltonian approach, we obtain conserved charges of the solutions and find that the black hole entropy still obeys the area formula and the gravitational field equation at the black hole horizon can be cast into a form similar to the first law of black hole thermodynamics. In the grand canonical ensemble, we find that the thermodynamics and phase structure depend on the combination $k-{\mu }^2/4+c_2{m}^2$ in the four-dimensional case, where $\mu$ is the chemical potential and $c_2{m}^2$ is the coefficient of the second term in the potential associated with the graviton mass. When it is positive, the Hawking-Page phase transition can happen; when as it is negative, the black hole is always thermodynamically stable with a positive capacity. In the canonical ensemble, the combination turns out to be $k+c_2{m}^2$ in the four-dimensional case. When it is positive, a first-order phase transition can happen between small and large black holes if the charge is less than its critical value. In the higher-dimensional [$(n+2)\ge 5$] case, even when the charge is absent, the small/large black hole phase transition can also appear, and the coefficients for the third ($c_3{m}^2$) and/or fourth ($c_4{m}^2$) terms in the potential associated with the graviton mass in massive gravity can play the same role as that of the charge in the four-dimensional case.