We consider minimally supersymmetric Yang-Mills theory with a Chern-Simons term on a flat spatial two-torus in the limit when the torus becomes small. The zero modes of the fields then decouple from the nonzero modes and give rise to a spectrum of states with energies that are given by multiples of the square of the coupling constant. We discuss the determination of this low-energy spectrum, both for simply connected gauge groups and for gauge groups of adjoint type, with a few examples worked out in detail.

We calculate the quantum corrections to the Newtonian potential induced by a massless, nonminimally coupled scalar field on Minkowski background. We make use of the graviton vacuum polarization calculated in our previous work and solve the equation of motion nonperturbatively. When written as the quantum-corrected gauge invariant Bardeen potentials, our results show that quantum effects generically antiscreen the Newtonian singularity $\propto 1/r$. This result supports the point of view that gravity on (super-)Planckian scales is an asymptotically safe theory. In addition, we show that, in the presence of quantum fluctuations of a massless, (non)minimally coupled scalar field, dynamical gravitons propagate superluminally. The effect is, however, unobservably small and it is hence of academic interest only.

Catalyzed symmetry breaking arises from a parametric enhancement of critical fluctuations independently of the coupling strength. Symmetry-breaking fermionic long-range fluctuations exhibit such an enhancement on negatively curved spaces, as is known from mean-field studies. We study gravitational catalysis from the viewpoint of the functional renormalization group using the $3d$ Gross-Neveu model as a specific example. We observe gravitational catalysis toward a phase of broken discrete chiral symmetry both on a maximally symmetric (anti–de Sitter) and on a purely spatially curved manifold for constant negative curvature (Lobachevsky plane). The resulting picture for gravitational catalysis obtained from the renormalization flow is closely related to that of magnetic catalysis. As an application, we estimate the curvature required for subcritical systems of finite length to acquire a gravitationally catalyzed gap.

Recently the lower bounds of the intergalactic magnetic fields ${10}^{-16}\sim {10}^{-20}\mathrm{G}$ are set by gamma-ray observations while it is unlikely to generate such large scale magnetic fields through astrophysical processes. It is known that large scale magnetic fields could be generated if there exist cosmological vector-mode perturbations in the primordial plasma. The vector mode, however, has only a decaying solution in general relativity if the plasma consists of perfect fluids. In order to investigate a possible mechanism of magnetogenesis in the primordial plasma, here we consider cosmological perturbations in the Einstein-aether gravity model, in which the aether field can act as a new source of vector metric perturbations. The vector metric perturbations induce the velocity difference between baryons and photons which then generate magnetic fields. This velocity difference arises from effects at the second order in the tight-coupling approximation. We estimate the angular power spectra of temperature and $B$-mode polarization of the cosmic microwave background anisotropies in this model and put a rough constraint on the aether field parameters from latest observations. We then estimate the power spectrum of associated magnetic fields around the recombination epoch within this limit. It is found that the spectrum has a characteristic peak at $k=0.1h{\mathrm{Mpc}}^{-1}$, and at that scale the amplitude can be as large as $B\sim {10}^{-22}\mathrm{G}$ where the upper bound comes from cosmic microwave background temperature anisotropies. The magnetic fields with this amplitude can be seeds of large scale magnetic fields observed today if the sufficient dynamo mechanism takes place. Analytic interpretation for the power spectra is also given.

The inflationary account for the emergence of the seeds of cosmic structure falls short of actually explaining the generation of primordial anisotropies and inhomogeneities. This description starts from a symmetric background, and invokes symmetric dynamics, so it cannot explain asymmetries. To generate asymmetries, we present an application of the continuous spontaneous localization model of wave function collapse in the context of inflation. This modification of quantum dynamics introduces a stochastic nonunitary component to the evolution of the inflaton field perturbations. This leads to passage from a homogeneous and isotropic stage to another, where the quantum uncertainties in the initial state of inflation transmute into the primordial inhomogeneities and anisotropies. We show, by proper choice of the collapse-generating operator, that it is possible to achieve compatibility with the precise observations of the cosmic microwave background radiation.

When D-branes are inserted in flux backgrounds of opposite charge, the resulting solution has a certain singularity in the fluxes. Recently it has been argued, using numerical solutions, that for anti-D3 branes in the Klebanov-Strassler background, these singularities cannot be cloaked by a horizon, which strongly suggests they are not physical. In this paper we provide an analytic proof that the singularity of all codimension-three antibrane solutions (such as anti-D6 branes in massive type IIA supergravity or anti-D3 branes smeared on the ${\mathbb{T}}^3$ of ${\mathbb{R}}^3\times {\mathbb{T}}^3$ with fluxes) cannot be hidden behind a horizon and that the charge of black branes with smooth event horizons must have the same sign as the charge of the flux background. Our result indicates that infinitesimally blackening the antibranes immediately triggers brane-flux annihilation and strengthens the intuition that antibranes placed in flux with positive charge immediately annihilate against it.

The presence of massive neutrinos has a characteristic impact on the growth of large scale structures such as galaxy clusters. We forecast on the capability of the number count and power spectrum measured from the ongoing and future Sunyaev-Zeldovich cluster surveys, combined with cosmic microwave background (CMB) observation to constrain the total neutrino mass $M_{\nu }$ in a flat $\Lambda \mathrm{CDM}$ cosmology. We adopt self-calibration for the mass-observable scaling relation and evaluate constraints for the South Pole Telescope normally and with polarization, Planck, and Atacama Cosmology Telescope Polarization surveys. We find that a sample of $\approx 1000$ clusters obtained from the Planck cluster survey plus extra information from CMB lensing extraction could tighten the current upper bound on the sum of neutrino masses to ${\sigma }_{M_{\nu }}=0.17\mathrm{eV}$ at 68% C.L. Our analysis shows that cluster number counts and the power spectrum provide complementary constraints, and as a result they help reducing the error bars on $M_{\nu }$ by a factor of 4–8 when both probes are combined. We also show that the main strength of cluster measurements in constraining $M_{\nu }$ is when good control of cluster systematics is available. When applying a weak prior on the mass-observable relations, which can be at reach in the upcoming cluster surveys, we obtain ${\sigma }_{M_{\nu }}=0.48\mathrm{eV}$ using cluster only probes and, more interestingly, ${\sigma }_{M_{\nu }}=0.08\mathrm{eV}$ using cluster $+$ CMB, which corresponds to a $S/N\approx 4$ detection for $M_{\nu }\ge 0.3\mathrm{eV}$. We analyze and discuss the degeneracies of $M_{\nu }$ with other parameters and investigate the sensitivity of neutrino mass constraints with various surveys specifications.

According to conventional wisdom, in the standard model (SM) of particle physics and cosmology the “effective number of neutrinos” measured in the late Universe is $N_{\mathrm{eff}}=3$ (more precisely, 3.046). For extensions of the standard model allowing for the presence of $\Delta N_{\nu }$ “equivalent neutrinos” (or “dark radiation”), it is generally the case that $N_{\mathrm{eff}}>3$. These canonical results are reconsidered, demonstrating that a measurement of $N_{\mathrm{eff}}>3$ can be consistent with $\Delta N_{\nu }=0$ (“dark radiation without dark radiation”). Conversely, a measurement consistent with $N_{\mathrm{eff}}=3$ is not inconsistent with the presence of dark radiation ($\Delta N_{\nu }>0$). In particular, if there is a light weakly interacting massive particle (WIMP) that annihilates to photons after the SM neutrinos have decoupled, the photons are heated beyond their usual heating from $e^{\pm }$ annihilation, reducing the late time ratio of neutrino and photon temperatures (and number densities), leading to $N_{\mathrm{eff}}<3$. This opens the window for one or more equivalent neutrinos, including “sterile neutrinos,” to be consistent with $N_{\mathrm{eff}}=3$. By reducing the neutrino number density in the present Universe, this also allows for more massive neutrinos, relaxing the current constraints on the sum of the neutrino masses. In contrast, if the light WIMP couples only to the SM neutrinos and not to the photons and $e^{\pm }$ pairs, its late time annihilation heats the neutrinos but not the photons, resulting in $N_{\mathrm{eff}}>3$ even in the absence of equivalent neutrinos or dark radiation. A measurement of $N_{\mathrm{eff}}>3$ is no guarantee of the presence of equivalent neutrinos or dark radiation. In the presence of a light WIMP and/or equivalent neutrinos, there are degeneracies among the light WIMP mass and its nature (fermion or boson, as well as its couplings to neutrinos and photons), the number and nature (fermion or boson) of the equivalent neutrinos, and their decoupling temperature (the strength of their interactions with the SM particles). As the analysis here reveals, there’s more to a measurement of $N_{\mathrm{eff}}$ than meets the eye.

If dark matter is mainly composed of axions, the density distribution can be nonuniformly distributed, being clumpy instead. By solving the Einstein-Klein-Gordon system of a scalar field with the potential energy density of an axionlike particle, we obtain the maximum mass of the self-gravitating system made of axions, called axion stars. The collision of axion stars with neutron stars may release the energy of axions due to the conversion of axions into photons in the presence of the neutron star’s magnetic field. We estimate the energy release and show that it should be much less than previous estimates [A. Iwazaki, Phys. Lett. B 486, 147 (2000); Phys. Rev. D 60, 025001 (1999)]. Future data from femtolensing should strongly constrain this scenario.

The magnetization of neutron star matter in magnetic fields is studied by employing the FSUGold interaction. It is found that the magnetic susceptibilities of the charged particles (proton, electron, and muon) can be larger than that of the neutron. The effects of the anomalous magnetic moments of each component on the magnetic susceptibility are examined in detail. It is found that the proton and electron anomalous magnetic moments affect their respective magnetic susceptibility evidently in strong magnetic fields. In addition, they are the protons instead of the electrons that contribute most significantly to the magnetization of the neutron star matter in a relative weak magnetic field, and the induced magnetic field due to the magnetization can appear to be very large. Finally, the effect of the density-dependent symmetry energy on the magnetization is discussed.

In this paper we investigate the localization and mass spectra of various matter fields with spin 0, 1 and $1/2$ on a geometric thick brane generated by pure four-dimensional (4D) and five-dimensional positive cosmological constants without bulk scalar fields. This model possesses a 4D cosmological constant that can be made as small as one desires without fine-tuning it with the bulk cosmological constant. The Randall-Sundrum model was obtained as an analytic continuation of the flat brane limit of this braneworld configuration when the Hubble parameter disappears. We also show that within the framework of this inflating braneworld model, it is possible to formulate a mechanism for obtaining TeV mass scales from Planck ones by adding a positive thin brane, where the Standard Model fields are trapped, located at a distance $y_2$ from the origin, where the Planck thick brane resides. The brane separation must be of the same order as the inverse thickness parameter of the model in order for the mechanism to generate the desired hierarchy. This result is obtained by imposing the recovery of both the correct 4D gravitational couplings and the actually observed accelerated expansion of the Universe in our de Sitter braneworld. Regarding the localization of matter in the purely geometric thick braneworld, for spin-0 massless and massive scalar fields as well as for spin-1 vector fields, the potentials of the Kaluza-Klein (KK) modes in the corresponding Schrödinger equations are modified Pöschl-Teller potentials, which lead to the localization of the scalar and vector zero modes on the brane as well as to mass gaps in the mass spectra. We also compute the corrections to Coulomb’s law coming from massive KK vector modes. For spin-$1/2$ fermions, we introduce the bulk mass term $MF(z)\overline{\Psi }\Psi$ in the action, and four different cases are investigated. Localization of the massless left-chiral fermion zero mode is feasible for just two cases of $F(z)$. In the first one, we obtain Schrödinger equations with modified Pöschl-Teller potentials with the corresponding mass gaps for both left- and right-chiral fermions; the number of massive KK bound states is finite (determined by the ratio $M/b$) and is the same for left- and right-chiral modes. In the second case, we get a family of solutions with an infinite number of bound states where the mass spectra for left- and right-chiral KK fermion modes are discrete. A special case resembles the one-dimensional quantum harmonic oscillator problem. For both of these cases, the mass spectrum of right-chiral fermions is shifted with respect to the mass spectrum of the left-chiral ones.

The basic principles of the correlation femtoscopy, including its correspondence to the Hanbury Brown and Twiss intensity interferometry, are reexamined. The main subject of the paper is an analysis of the correlation femtoscopy when the source size is as small as the order of the uncertainty limit. It is about 1 fm for the current high energy experiments. Then the standard femtoscopy model of random sources is inapplicable. The uncertainty principle leads to the partial indistinguishability and coherence of closely located emitters that affect the observed femtoscopy scales. In thermal systems the role of corresponding coherent length is taken by the thermal de Broglie wavelength that also defines the size of a single emitter. The formalism of partially coherent phases in the amplitudes of closely located individual emitters is used for the quantitative analysis. The general approach is illustrated analytically for the case of the Gaussian approximation for emitting sources. A reduction of the interferometry radii and a suppression of the Bose-Einstein correlation functions for small sources due to the uncertainty principle are found. There is a positive correlation between the source size and the intercept of the correlation function. The peculiarities of the nonfemtoscopic correlations caused by minijets and fluctuations of the initial states of the systems formed in $pp$ and $e^{+}{e}^{-}$ collisions are also analyzed. The factorization property for the contributions of femtoscopic and nonfemtoscopic correlations into complete correlation function is observed in numerical calculations in a wide range of the model parameters.

We discuss inclusive production of open charm in proton-proton scattering at LHC. The calculation is performed within the $k_t$-factorization approach. Different models of unintegrated gluon distributions (UGDFs) from the literature are used. The theoretical transverse momentum as well as (pseudo)rapidity distributions of charmed mesons are compared with recent experimental data of the ATLAS, ALICE, and LHCb Collaborations. Only the calculation with Kimber-Martin-Ryskin UGDF gives results comparable to experimental ones. All other popular models of UGDF significantly underpredict experimental data. Several sources of uncertainties of the theoretical predictions are also studied in detail. In addition, we discuss correlations between $D$ and $\overline{D}$ mesons. Good description of experimental distribution in invariant mass and in relative azimuthal angle between $D$ and $\overline{D}$ mesons is achieved for the Kimber-Martin-Ryskin UGDF. The considered correlation observables measured by the LHCb experiment were not discussed in other approaches in the literature

We explore the effects of the resummation of large logarithmic perturbative corrections to double-longitudinal spin asymmetries for inclusive and semi-inclusive deep inelastic scattering in fixed-target experiments. We find that the asymmetries are overall rather robust with respect to the inclusion of the resummed higher-order terms. Significant effects are observed at fairly high values of $x$, where resummation tends to decrease the spin asymmetries. This effect turns out to be more pronounced for semi-inclusive scattering. We also investigate the potential impact of resummation on the extraction of polarized valence quark distributions in dedicated high-$x$ experiments.

Based on a sample of $2.25\times {10}^8$ $J/\psi$ events collected with the BESIII detector at BEPCII, a full partial wave analysis on $J/\psi \to \gamma \eta \eta$ was performed using the relativistic covariant tensor amplitude method. The results show that the dominant $0^{++}$ and $2^{++}$ components are from the $f_0(1710)$, $f_0(2100)$, $f_0(1500)$, $f_2^{\prime }(1525)$, $f_2(1810)$ and $f_2(2340)$. The resonance parameters and branching fractions are also presented.

A search is presented for free heavy long-lived fractionally charged particles produced in $pp$ collisions at $\sqrt{s}=7\mathrm{TeV}$. The data sample was recorded by the CMS detector at the LHC and corresponds to an integrated luminosity of $5.0{\mathrm{fb}}^{-1}$. Candidate fractionally charged particles are identified by selecting tracks with associated low charge measurements in the silicon tracking detector. Observations are found to be consistent with expectations for background processes. The results of the search are used to set upper limits on the cross section for pair production of fractionally charged, massive spin-$1/2$ particles that are neutral under $SU(3{)}_C$ and $SU(2{)}_L$. We exclude at 95% confidence level such particles with electric charge $\pm 2e/3$ with masses below 310 GeV, and those with charge $\pm e/3$ with masses below 140 GeV.

First observations and measurements of the branching fractions of the ${\overline{B}}_s^0\to D^{+}{D}^{-}$, ${\overline{B}}_s^0\to D_s^{+}{D}^{-}$ and ${\overline{B}}_s^0\to D^0{\overline{D}}^0$ decays are presented using $1.0{\mathrm{fb}}^{-1}$ of data collected by the LHCb experiment. These branching fractions are normalized to those of ${\overline{B}}^0\to D^{+}{D}^{-}$, $B^0\to D^{-}{D}_s^{+}$ and $B^{-}\to D^0{D}_s^{-}$, respectively. An excess of events consistent with the decay ${\overline{B}}^0\to D^0{\overline{D}}^0$ is also seen, and its branching fraction is measured relative to that of $B^{-}\to D^0{D}_s^{-}$. Improved measurements of the branching fractions $\mathcal{B}({\overline{B}}_s^0\to D_s^{+}{D}_s^{-})$ and $\mathcal{B}(B^{-}\to D^0{D}_s^{-})$ are reported, each relative to $\mathcal{B}(B^0\to D^{-}{D}_s^{+})$. The ratios of branching fractions are $\frac{\mathcal{B}({\overline{B}}_s^0\to D^{+}{D}^{-})}{\mathcal{B}({\overline{B}}^0\to D^{+}{D}^{-})}=1.08\pm 0.20\pm 0.10$, $\frac{\mathcal{B}({\overline{B}}_s^0\to D_s^{+}{D}^{-})}{\mathcal{B}(B^0\to D^{-}{D}_s^{+})}=0.050\pm 0.008\pm 0.004$, $\frac{\mathcal{B}({\overline{B}}_s^0\to D^0{\overline{D}}^0)}{\mathcal{B}(B^{-}\to D^0{D}_s^{-})}=0.019\pm 0.003\pm 0.003$, $\frac{\mathcal{B}({\overline{B}}^0\to D^0{\overline{D}}^0)}{\mathcal{B}(B^{-}\to D^0{D}_s^{-})}<0.0024$ at 90% CL, $\frac{\mathcal{B}({\overline{B}}_s^0\to D_s^{+}{D}_s^{-})}{\mathcal{B}(B^0\to D^{-}{D}_s^{+})}=0.56\pm 0.03\pm 0.04$, $\frac{\mathcal{B}(B^{-}\to D^0{D}_s^{-})}{\mathcal{B}(B^0\to D^{-}{D}_s^{+})}=1.22\pm 0.02\pm 0.07$, where the uncertainties are statistical and systematic, respectively.

We identify a natural analytic continuation in four dimensions from Minkowski signature to a signature with two timelike momentum components. For two-, three-, and four-point diagrams whose external momenta define a scattering plane, this continuation can be implemented as a contour deformation that leaves dependence on the momenta unchanged. For arbitrary ultraviolet-finite scalar diagrams it is possible to do two integrals per loop in terms of simple poles in the new signature. This results in a representation of any such diagram as a sum of terms, each with two remaining integrals per loop.

We present an elementary derivation of the width of photon decay in a weak magnetic field using the semiclassical method of worldline instantons. The calculation is generalized to a model of quantum electrodynamics with broken Lorentz symmetry. Implications for the search of deviations from Lorentz invariance in the cosmic ray experiments are discussed.