We apply a formalism inspired by heavy-baryon chiral perturbation theory with finite-range regularization to dynamical $2+1$-flavor CSSM/QCDSF/UKQCD Collaboration lattice QCD simulation results for the electric form factors of the octet baryons. The electric form factor of each octet baryon is extrapolated to the physical pseudoscalar masses, after finite-volume corrections have been applied, at six fixed values of $Q^2$ in the range $0.2–1.3{\mathrm{GeV}}^2$. The extrapolated lattice results accurately reproduce the experimental form factors of the nucleon at the physical point, indicating that omitted disconnected quark loop contributions are small relative to the uncertainties of the calculation. Furthermore, using the results of a recent lattice study of the magnetic form factors, we determine the ratio ${\mu }_p{G}_E^p/G_M^p$. This quantity decreases with $Q^2$ in a way qualitatively consistent with recent experimental results.

We study the effect of laser photon merging, or equivalently high harmonic generation, in the quantum vacuum subject to inhomogeneous electromagnetic fields. Such a process is facilitated by the effective nonlinear couplings arising from charged particle-antiparticle fluctuations in the quantum vacuum subject to strong electromagnetic fields. We derive explicit results for general kinematic and polarization configurations involving optical photons. Concentrating on merged photons in reflected channels which are preferable in experiments for reasons of noise suppression, we demonstrate that photon merging is typically dominated by the competing nonlinear process of quantum reflection, though appropriate polarization and signal filtering could specifically search for the merging process. As a byproduct, we devise a novel systematic expansion of the photon polarization tensor in plane wave fields.

The Milky Way can act as a large-scale weak gravitational lens of the cosmic microwave background (CMB). We study this effect using a photon ray-tracing code and a Galactic mass distribution with disk, bulge and halo components. For an observer at the Sun’s coordinates in the Galaxy, the bending of CMB photon paths is limited to less than one arcsecond, and only for rays that pass within a few degrees of the Galactic Center. However, the entire sky is affected, resulting in global distortions of the CMB on large angular scales. These distortions can cause the low-order multipoles of a spherical harmonic expansion of the CMB sky temperature to leak into higher-order modes. Thus the component of the CMB dipole that results from the Local Group’s motion relative to the local cosmic frame of rest contributes to higher-order moments for an observer in the solar system. With our ray-tracing code we show that the phenomenon is not sensitive to the specific choice of Galactic potential. We also quantitatively rule it out as a contributor to CMB anomalies such as power asymmetry or correlated alignment of low-order multipole moments.

We consider the finite temperature Casimir interaction between two Dirichlet spheres in $(D+1)$-dimensional Minkowski spacetime. The Casimir interaction free energy is derived from the zero temperature Casimir interaction energy via the Matsubara formalism. In the high temperature region, the Casimir interaction is dominated by the term with zero Matsubara frequency, and it is known as the classical term since this term is independent of the Planck constant $\hslash$. Explicit expression of the classical term is derived and it is computed exactly using appropriate similarity transforms of matrices. We then compute the small separation asymptotic expansion of this classical term up to the next-to-leading order term. For the remaining part of the finite temperature Casimir interaction with nonzero Matsubara frequencies, we obtain its small separation asymptotic behavior by applying certain prescriptions to the corresponding asymptotic expansion at zero temperature. This gives us a leading term that is shown to agree precisely with the proximity force approximation at any temperature. The next-to-leading order term at any temperature is also derived and it is expressed as an infinite sum over integrals. To obtain the asymptotic expansion at the low and medium temperature regions, we apply the inverse Mellin transform techniques. In the low temperature region, we obtain results that agree with our previous work on the zero temperature Casimir interaction.

We study the holographic dual of fermions interacting in a Schwarzschild-${\mathrm{AdS}}_{d+1}$ background via a dipole (Pauli) coupling sourced by a probe gauge field. We find quite generally that a gap forms in the dual operator spectrum as the Pauli coupling is strengthened. Previous investigations have observed this behavior in analogous constructions with Reissner-Nordström-AdS ($\mathrm{RN}\text{−}{\mathrm{AdS}}_4$) backgrounds, but the emergence of log-oscillatory behavior in those models’ spectra prevented identification of the underlying gapping mechanism. Our model obviates this issue through its modified geometry and traces the gapping mechanism back to the bulk dynamics. We show in general that there is a duality between zeros for large positive values of the coupling and poles in the spectrum for equivalent couplings but with opposite sign as seen recently in the $\mathrm{RN}\text{−}{\mathrm{AdS}}_4$ background by Alsup et al. The duality arises from the two possible quantizations for computing the retarded propagator. Coupled with the earlier string results [J. P. Gauntlett, J. Sonner, and D. Waldram, Phys. Rev. Lett. 107, 241601 (2011); O. DeWolfe, S. S. Gubser, and C. Rosen, Phys. Rev. Lett. 108, 251601 (2012)] that Fermi surfaces are generally absent from the spectral function, our finding that the Pauli term engineers the gap suggests that the model examined here offers a way of studying nonperturbative physics in fermionic matter at finite density typified by Mott insulating systems.

A scalar field equivalent to a nonideal “dark energy fluid” obeying a Shan-Chen-like equation of state is used as the background source of a flat Friedmann-Robertson-Walker cosmological spacetime to describe the inflationary epoch of our Universe. Within the slow-roll approximation, a number of interesting features are presented, including the possibility to fulfill current observational constraints as well as a graceful exit mechanism from the inflationary epoch.

There are certain black hole solutions in general relativity which are conformally related to the stationary solutions in general relativity. It is not obvious that the horizon entropy of these spacetimes is also one quarter of the area of the horizon, like the stationary ones. Here I study this topic in the context of Virasoro algebra and the Cardy formula. Using the fact that the conformal spacetime admits the conformal Killing vector and the horizon is determined by the vanishing of the norm of it, the diffeomorphisms are obtained which keep the near horizon structure invariant. The Noether charge and a bracket among them corresponding to these vectors are calculated in this region. Finally, they are evaluated for the Sultana-Dyer black hole, which is conformal to the Schwarzschild metric. It is found that the bracket is identical to the usual Virasoro algebra with the central extension. Identifying the zero mode eigenvalue and the central charge, the entropy of the Sultana-Dyer horizon is obtained by using the Cardy formula. Interestingly, this is again one quarter of the horizon area. Only difference in this case is that the area is modified by the conformal factor compared to that of the stationary one. The analysis gives a direct proof of the earlier assumption.

We analyze quantum corrections on the naive ${\varphi }^4$ inflation. These typically lead to an inflaton potential which carries a noninteger power of the field. We consider both minimal and nonminimal couplings to gravity. For the latter case we also study unitarity of inflaton-inflaton scattering. Finally we confront these theories with the Planck and BICEP2 data. We demonstrate that the presence of nonvanishing primordial tensor modes requires sizable quantum departures from the ${\varphi }^4$-inflation model for the nonminimally coupled scenario which we parametrize and quantify. We compare the results with the minimally coupled case and elucidate the main distinctive features.

The IceCube Collaboration has recently reported the observation of a flux of high-energy astrophysical neutrinos. The angular distribution of events is consistent with an isotropic arrival direction of neutrinos which is expected for an extragalactic origin. We estimate the prospects of detecting individual neutrino sources from a quasidiffuse superposition of many extragalactic sources at the level of the IceCube observation. Unlike previous analyses, we take into account ensemble variations of the source distribution as well as the event statistics of individual sources. We show that IceCube in its present configuration is sensitive to rare $\lesssim {10}^{-8}{\mathrm{Mpc}}^{-3}{\mathrm{yr}}^{-1}$ transient source classes within five years of operation via the observation of event clusters. Identification of time-independent sources is more challenging due to larger backgrounds. We estimate that during the same period IceCube is sensitive to sparse sources with densities of $\lesssim {10}^{-6}{\mathrm{Mpc}}^{-3}$ via association of events with the closest 100 sources of an ensemble. We show that a next-generation neutrino observatory with 5 times the effective area of IceCube and otherwise similar detector performance would increase the sensitivity to source densities and rates by about 2 orders of magnitude.

LISA Pathfinder (LPF), the precursor mission to a gravitational wave observatory of the European Space Agency, will measure the degree to which two test masses can be put into free fall, aiming to demonstrate a suppression of disturbance forces corresponding to a residual relative acceleration with a power spectral density (PSD) below $(30\mathrm{fm}/{\mathrm{s}}^2/\sqrt{\mathrm{Hz}}{)}^2$ around 1 mHz. In LPF data analysis, the disturbance forces are obtained as the difference between the acceleration data and a linear combination of other measured data series. In many circumstances, the coefficients for this linear combination are obtained by fitting these data series to the acceleration, and the disturbance forces appear then as the data series of the residuals of the fit. Thus the background noise or, more precisely, its PSD, whose knowledge is needed to build up the likelihood function in ordinary maximum likelihood fitting, is here unknown, and its estimate constitutes instead one of the goals of the fit. In this paper we present a fitting method that does not require the knowledge of the PSD of the background noise. The method is based on the analytical marginalization of the posterior parameter probability density with respect to the background noise PSD, and returns an estimate both for the fitting parameters and for the PSD. We show that both these estimates are unbiased, and that, when using averaged Welch’s periodograms for the residuals, the estimate of the PSD is consistent, as its error tends to zero with the inverse square root of the number of averaged periodograms. Additionally, we find that the method is equivalent to some implementations of iteratively reweighted least-squares fitting. We have tested the method both on simulated data of known PSD and on data from several experiments performed with the LISA Pathfinder end-to-end mission simulator.

We consider two classes of supersymmetric models with nonuniversal gaugino masses at the grand unification scale $M_{\mathrm{GUT}}$ in an attempt to resolve the apparent muon $g-2$ anomaly encountered in the Standard Model. We explore two distinct scenarios, one in which all gaugino masses have the same sign at $M_{\mathrm{GUT}}$, and a second case with opposite sign gaugino masses. The sfermion masses in both cases are assumed to be universal at $M_{\mathrm{GUT}}$. We exploit the nonuniversality among gaugino masses to realize large mass splitting between the colored and noncolored sfermions. Thus, the sleptons can have masses in the few hundred GeV range, whereas the colored sparticles turn out to be an order of magnitude or so heavier. In both models the resolution of the muon $g-2$ anomaly is compatible, among other things, with a 125–126 GeV Higgs boson mass and the WMAP dark matter bounds.

We study the influence of an external magnetic field on the deconfinement transition in two-flavor lattice QCD with physical quark charges. We use dynamical overlap fermions without any approximation such as fixed topology and perform simulations on a ${16}^3\times 6$ lattice and at a pion mass around 500 MeV. The pion mass (as well as the lattice spacing) was determined in independent runs on ${12}^3\times 24$ lattices. We consider two temperatures, one of which is close to the deconfinement transition and the other of which is above. Within our limited statistics, the dependence of the Polyakov loop and chiral condensate on the magnetic field supports the “inverse magnetic catalysis” scenario in which the transition temperature decreases as the field strength grows for temperature not to far above the critical temperature.

In most meson strong decay and unquenched (coupled-channel) quark models, the pair-creation operator is a scalar product of vectors in the spin and spatial degrees of freedom. While differing in the spatial part, most models have the same spin part, which creates a $q\overline{q}$ pair coupled to spin triplet, with the spins of the initial quarks as spectators. This is a basic assumption of the ${{}^3\mathrm{P}}_0$ model, and is well known to arise also in the flux tube model, starting from the strong coupling expansion of lattice QCD. In this article the same structure is shown to emerge in the Cornell model, in the dominant contributions of a more general microscopic decay model, and in the pseudoscalar-meson emission model. A solution is obtained for arbitrary matrix elements in these “nonflip, triplet” models, expressed as a weighted sum over spatial matrix elements. The coefficients in the expansion, which involve the spin degrees of freedom and the associated angular momentum algebra, are model independent. Tables of the angular momentum coefficients are presented which can be used in future calculations, avoiding tedious Clebsch-Gordan sums. The symmetry and orthogonality properties of the coefficients are discussed, as well as their application to transitions involving hybrid mesons and states of mixed spin. New selection rules are derived, and existing ones generalized. The coefficients lead to model-independent relations among decay amplitudes and widths which can be tested in experiment and lattice QCD. They can also be used to explain how mass shifts in the unquenched quark model do not spoil successful predictions of the ordinary (quenched) quark model.

We perform the threshold resummation for $W^{\pm }Z$ and $ZZ$ pair production at the next-to-next-to-leading logarithmic accuracy in soft-collinear effective theory at the LHC. Our results show that the resummation effects increase the total cross sections by about 7% for $ZZ$ production and 12% for $W^{\pm }Z$ production with $\sqrt{S}=7$, 8, 13 and 14 TeV, respectively, and the scale uncertainties are significantly reduced. Besides, our numerical results are consistent with experimental data reported by the ATLAS and CMS collaborations.

The China Dark Matter Experiment reports results on light WIMP dark matter searches at the China Jinping Underground Laboratory with a germanium detector array with a total mass of 20 g. The physics threshold achieved is 177 eVee (“ee” represents electron equivalent energy) at 50% signal efficiency. With 0.784 kg-days of data, exclusion region on spin-independent coupling with the nucleon is derived, improving over our earlier bounds at WIMP mass less than 4.6 GeV.

We investigate brane-world models in different viable $F(R)$ gravity theories where the Lagrangian is an arbitrary function of the curvature scalar. Deriving the warped metric for this model, resembling Randal-Sundrum (RS)-like solutions, we determine the graviton KK modes. The recent observations at the LHC, which constrain the RS graviton KK modes to a mass range greater than 3 TeV, are incompatible with RS model predictions. It is shown that the models with $F(R)$ gravity in the bulk address the issue, which in turn constrains the $F(R)$ model itself.

In this paper, we have extended a three-dimensional Faddeev scheme for three-quark bound state calculations in momentum space. To this end, we have solved Faddeev integral equation by inserting a screened quark-quark potential numerically. Finally, we have obtained binding energy and mass of triply heavy baryons ${\mathrm{\Omega }}_{ccc}^{++}$ and ${\mathrm{\Omega }}_{bbb}^{-}$.

We discuss a novel mechanism for segregation of baryons and antibaryons in the quark-gluon plasma phase which can lead to formation of quark and antiquark nuggets in the early universe, irrespective of the order of the quark-hadron phase transition. This happens due to $CP$ violating scattering of quarks and antiquarks from moving $Z(3)$ domain walls. $CP$ violation here is spontaneous in nature and arises from the nontrivial profile of the background gauge field ($A_0$) between different $Z(3)$ vacua. We study the effect of this spontaneous $CP$ violation on the baryon transport across the collapsing large $Z(3)$ domain walls (which can arise in the context of certain low energy scale inflationary models). Our results show that this $CP$ violation can lead to large concentrations of baryons and antibaryons in the early universe. The quark and antiquark nuggets, formed by this alternate mechanism, can provide a viable dark matter candidate within standard model without violating any observational constraints.

We calculate the orbits of a particle in Schwarzschild spacetime, assuming that the dynamics is governed by a Snyder symplectic structure. With this assumption, the perihelion shift of the planets acquires an additional contribution with respect to the one predicted by general relativity. Moreover, the equivalence principle is violated. If one assumes that Snyder mechanics is valid also for macroscopic systems, these results impose strong constraints on the value of the coupling parameter of the Snyder model.