We use chiral perturbation theory for $SU(2)$ to compute the leading loop corrections to the thermal mass of the pions and the pion decay constant in the presence of a constant magnetic field $B$. The magnetic field gives rise to a splitting between $M_{{\pi }^0}$ and $M_{{\pi }^{\pm }}$ as well as $F_{{\pi }^0}$ and $F_{{\pi }^{\pm }}$. We also calculate the free energy and the quark condensate to next-to-leading order in chiral perturbation theory. The results suggest that the critical temperature $T_c$ for the chiral transition is larger in the presence of a constant magnetic field, in agreement with most model calculations but in disagreement with recent lattice calculations.

We test the stability of various wormholes and black holes supported by a scalar field with a negative kinetic term. The general axial perturbations and the monopole type of polar perturbations are considered in the linear approximation. Two classes of objects are considered: (i) wormholes with flat asymptotic behavior at one end and anti-de Sitter on the other (Minkowski–anti-de Sitter wormholes) and (ii) regular black holes with asymptotically de Sitter expansion far beyond the horizon (the so-called black universes). A difficulty in such stability studies is that the effective potential for perturbations forms an infinite wall at throats, if any. Its regularization is in general possible only by numerical methods, and such a method is suggested in a general form and used in the present paper. As a result, we have shown that all configurations under study are unstable under spherically symmetric perturbations, except for a special class of black universes where the event horizon coincides with the minimum of the area function. For this stable family, the frequencies of quasinormal modes of axial perturbations are calculated.

In a previous paper, based on a calculation in the nonrelativistic quark model, we advanced the hypothesis that the $D_s(2317)$, $D_0(2308)$ mesons are predominantly four-quark states lowered in mass by the flavor-dependent Kobayashi-Kubo-Maskawa ’t Hooft $U_A(1)$ symmetry breaking effective interaction. Here we show similar results and conclusions in a relativistic effective chiral model calculation, based on three-light-quark (i.e., two $q$ plus one $\overline{q}$) local interpolators. To this end we classify the four-quark (three light plus one heavy quark) local interpolators according to their chiral transformation properties and then construct chiral invariant interactions. We evaluate the diagonal matrix elements of the Kobayashi-Kubo-Maskawa ’t Hooft interaction between different interpolating fields and show that the lowest-lying one is always the (antisymmetric) $SU(3{)}_F$ antitriplet belonging to the chiral (3, 3) multiplet. We predict bottom-strange $B_{s0}$ and the bottom-nonstrange $B_0$ scalar mesons with equal masses at 5720 MeV, the strange meson being some 100 MeV lower than in most of the quark potential models. We also predict the $J^P=1^{+}$ bottom-nonstrange $B_1$ and the bottom-strange $B_{s1}$ meson masses as 5732 MeV and 5765 MeV, respectively, using the Bardeen-Hill-Nowak-Rho-Zahed scalar-vector mass relation.

Using the explicit form of the known single distribution functions (the Green’s functions) in the double logarithm approximation of perturbative QCD, we analyze the structure of splitting diagrams as a source of double parton perturbative correlations in the proton. The related phenomenological effects are discussed for the conditions of the LHC experiments.

The experimental uncertainty on the branching fraction $\mathcal{B}({\Lambda }_c\to p{K}^{-}{\pi }^{+})=(5.0\pm 1.3)\%$ has not decreased since 1998, despite a much larger data sample. Uncertainty in this quantity dominates that in many other quantities, including branching fractions of ${\Lambda }_c$ to other modes, branching fractions of $b$-flavored baryons, and fragmentation fractions of charmed and bottom quarks. Here we advocate a lattice QCD calculation of the form factors in ${\Lambda }_c\to \Lambda {\ell }^{+}{\nu }_{\ell }$ (the case $\ell =e^{+}$ is simpler as the mass of the lepton can be neglected). Such a calculation would yield an absolute prediction for the rate for ${\Lambda }_c\to \Lambda {\ell }^{+}{\nu }_{\ell }$. When combined with the ${\Lambda }_c$ lifetime, it could provide a calibration for an improved set of ${\Lambda }_c$ branching fractions as long as the accuracy exceeds about 25%.

The Tevatron has measured a discrepancy relative to the standard model prediction in the forward-backward asymmetry in top quark pair production. This asymmetry grows with the rapidity difference of the two top quarks. It also increases with the invariant mass of the $\overline{t}t$ pair, reaching, for high invariant masses, 3.4 standard deviations above the next-to-leading order prediction for the charge asymmetry of QCD. However, perfect agreement between experiment and the standard model was found in both total and differential cross section of top quark pair production. As this result could be a sign of new physics we have parametrized this new physics in terms of a complete set of dimension six operators involving the top quark. We have then used a Markov chain Monte Carlo approach in order to find the best set of parameters that fits the data, using all available data regarding top quark pair production at the Tevatron. We have found that just a very small number of operators are able to fit the data better than the standard model.

A search for first-generation leptoquarks was performed in electron-proton and positron-proton collisions recorded with the ZEUS detector at HERA in 2003–2007 using an integrated luminosity of $366{\mathrm{pb}}^{-1}$. Final states with an electron and jets or with missing transverse momentum and jets were analyzed, searching for resonances or other deviations from the standard model predictions. No evidence for any leptoquark signal was found. The data were combined with data previously taken at HERA, resulting in a total integrated luminosity of $498{\mathrm{pb}}^{-1}$. Limits on the Yukawa coupling, $\lambda$, of leptoquarks were set as a function of the leptoquark mass for different leptoquark types within the Buchmüller-Rückl-Wyler model. Leptoquarks with a coupling $\lambda =0.3$ are excluded for masses up to 699 GeV.

We extend the $SO(4,2)$ covariant lightcone embedding methods of four-dimensional CFTs to $\mathcal{N}=1$ superconformal field theory (SCFT). Manifest superconformal $SU(2,2|1)$ invariance is achieved by realizing 4D superconformal space as a surface embedded in the projective superspace spanned by certain complex chiral supermatrices. Because $SU(2,2|1)$ acts linearly on the ambient space, the constraints on correlators implied by superconformal Ward identities are automatically solved in this formalism. Applications include new, compact expressions for correlation functions containing one antichiral superfield and arbitrary chiral superfield insertions, and manifestly invariant expressions for the superconformal cross ratios that parametrize the four-point function of two chiral and two antichiral fields. Superconformal expressions for the leading singularities in the operator product expansion of chiral and antichiral operators are also given. Because of covariance, our expressions should hold in any superconformally flat background, e.g., ${\mathrm{AdS}}_4$ or $\mathbf{R}\times {\mathbf{S}}^3$.

The center-of-mass energy of two particles colliding near the horizon of a maximally rotating black hole can be arbitrarily high if the angular momentum of either of the incident particles is fine-tuned, which we call a critical particle. We study particle emission from such high-energy collision and reaction in the equatorial plane fully analytically. We show that the unconditional upper limit of the energy of the emitted particle is given by 218.6% of that of the injected critical particle, irrespective of the details of the reaction and this upper limit can be realized for massless particle emission. The upper limit of the energy extraction efficiency for this emission as a collisional Penrose process is given by 146.6%, which can be realized in the collision of two massive particles with optimized mass ratio. Moreover, we analyze perfectly elastic collision, Compton scattering, and pair annihilation and show that net positive energy extraction is really possible for these three reactions. The Compton scattering is most efficient among them and the efficiency can reach 134.3%. On the other hand, our result is qualitatively consistent with the earlier claim that the mass and energy of the emitted particle are at most of order the total energy of the injected particles and hence we can observe neither super-heavy nor super-energetic particles. The present paper places the baseline for the study of particle emission from high-energy collision near a rapidly rotating black hole.

The purpose of this paper is to further study the soft-wall AdS/QCD model with constrained IR background proposed in [1]. By including a quartic bulk scalar potential we study various meson and nucleon spectra. This model naturally realizes the asymptotical linearity of these mass spectra simultaneously, together with correct patterns of explicit and dynamical chiral symmetry breaking. The agreement between the theoretical calculations and the experimental data is good.

We construct a supersymmetric generalization of the holographic dual of a fractional topological insulator found in [23]. This is accomplished by introducing a nontrivial gauge field on the world volume of the probe $D7$-brane. The Bogomol’nyi-Prasad-Sommerfeld monopoles (BPS) equations are derived from the $\kappa$-symmetry transformation of the probe brane. The BPS equations are shown to reduce to two first-order nonlinear partial differential equations. Solutions of the BPS equations correspond to a probe brane configuration which preserves four of the 32 supersymmetries of the $Ad{S}_5\times S^5$ background. Solutions of the BPS equations which correspond to a holographic fractional topological insulator are obtained numerically.

The $\mathcal{N}=4$ super Yang-Mills plasma is studied in the regime of weak coupling. Collective excitations and collisional processes are discussed. Since the Keldysh-Schwinger approach is used, the collective excitations in both equilibrium and nonequilibrium plasma are under consideration. The dispersion equations of gluon, fermion, and scalar fields are written down and the self-energies, which enter the equations, are computed in the hard loop approximation. The self-energies are discussed in the context of effective action which is also given. The gluon modes and fermion ones appear to be the same as those in the QCD plasma of gluons and massless quarks. The scalar modes are as of a free relativistic massive particle. The binary collisional processes, which occur at the lowest nontrivial order of the coupling constant, are reviewed and then the transport properties of the plasma are discussed. The $\mathcal{N}=4$ super Yang-Mills plasma is finally concluded to be very similar to the QCD plasma of gluons and light quarks. The differences mostly reflect different numbers of degrees of freedom in the two systems.

We consider cosmic microwave background constraints on inflation models for which the primordial power spectrum is a mixture of perturbations generated by inflaton fluctuations and fluctuations in a curvaton field. If future experiments do not detect isocurvature modes or large non-Gaussianity, it will not be possible to directly distinguish inflaton and curvaton contributions. We investigate whether current and future data can instead constrain the relative contributions of the two sources. We model the spectrum with a bimodal form consisting of a sum of two independent power laws, with different spectral indices. We quantify the ability of current and upcoming data sets to constrain the difference $\Delta n$ in spectral indices, and relative fraction $f$ of the subdominant power spectrum at a pivot scale of $k_0=0.017\mathrm{Mp}{\mathrm{c}}^{-1}h$. Data sets selected are the WMAP 7-year data, alone and in conjunction with South Pole Telescope data, and a synthetic data set comparable to the upcoming Planck data set. We find that current data show no increase in quality of fit for a mixed inflaton/curvaton power spectrum, and a pure power-law spectrum is favored. The ability to constrain independent parameters such as the tensor/scalar ratio is not substantially affected by the additional parameters in the fit. Planck will be capable of placing significant constraints on the parameter space for a bimodal spectrum.

Among three typical energy scales, a neutrino mass scale ($m_{\nu }\sim 0.1\mathrm{eV}$), a grand unified theory (GUT) scale ($M_{\mathrm{GUT}}\sim {10}^{16}\mathrm{GeV}$), and a TeV scale ($M_{NP}\sim 1\mathrm{TeV}$), there is the fascinating relation of $M_{NP}\simeq \sqrt{m_{\nu }·M_{\mathrm{GUT}}}$. The TeV scale, $M_{NP}$, is a new physics scale beyond the standard model which is regarded as “supersymmetry” in this article. We investigate the phenomenology of the supersymmetry $SU(5)$ GUT with neutrinophilic Higgs, where the above relation is realized dynamically when neutrinos are Dirac particles. As a remarkable feature of this model, accurate gauge coupling unification can be achieved in keeping with a proton stability. We also evaluate flavor changing processes in quark/lepton sectors.

Evidence of $CP$ violation in the charm sector has been observed recently by the LHCb and CDF collaborations. Adopting the topological diagram approach, we study flavor SU(3) symmetry breaking effects in the weak decay tree amplitudes of singly Cabibbo-suppressed $D\to PP$ decays. The symmetry breaking in the color-allowed and color-suppressed amplitudes is estimated with the help of the factorization ansatz, while that in the $W$-exchange amplitude is done by fitting to related branching fraction data. We find that the $W$-exchange amplitudes stay in the second quadrant relative to the color-allowed tree amplitude, albeit there are two possibilities for one type of $W$-exchange amplitude. The weak decay penguin amplitudes, on the other hand, are evaluated within the framework of QCD factorization. Using the input of topological tree amplitudes extracted from the Cabibbo-favored decay modes and the perturbative results for QCD-penguin amplitudes, we make predictions for the branching fractions and $CP$ asymmetries of singly Cabibbo-suppressed modes. The predictions of branching fractions are generally improved from those in the SU(3) limit. We conclude that the direct $CP$ asymmetry difference between $D^0\to K^{+}{K}^{-}$ and $D^0\to {\pi }^{+}{\pi }^{-}$ is about $-(0.139\pm 0.004)\%$ and $-(0.151\pm 0.004)\%$ for the two solutions of $W$-exchange amplitudes, respectively. We also find that the $CP$ asymmetry of $D^0\to K^0{\overline{K}}^0$ dominated by the interference between $W$-exchange amplitudes ranges from $-0.62\times {10}^{-3}$ to $-1.82\times {10}^{-3}$. We study phenomenological implications of two new physics scenarios for explaining the observed $CP$ asymmetry in the charm sector, one with large penguin amplitudes and the other with a large chromomagnetic dipole operator. We find that the two scenarios can be discriminated by the measurements of $CP$ asymmetries of a set of decay modes.

The important consequences of the recent results of the numerical evaluations of eighth- and tenth-order QED contributions to the anomalous magnetic moment of electrons are commented upon on this paper. The correctness of the results of the numerical evaluation of the new eighth-order QED corrections to the electron anomaly are supported by the demonstration of their consistency with the presented in this work analytical expressions QED contributions to $a_e$ from the diagrams with fourth-order light-by-light scattering muon and tau-lepton loops. The consistency of similar analytical and numerical results is demonstrated in the case of eighth-order mass-dependent contributions to the muon’s anomalous magnetic moment.

We present a search for the lepton flavor violating decay modes $B^{\pm }\to h^{\pm }\tau \ell$ ($h=K$, $\pi$; $\ell =e$, $\mu$) using the BABAR data sample, which corresponds to $472\times {10}^6$ $B\overline{B}$ pairs. The search uses events where one $B$ meson is fully reconstructed in one of several hadronic final states. Using the momenta of the reconstructed $B$, $h$, and $\ell$ candidates, we are able to fully determine the $\tau$ four-momentum. The resulting $\tau$ candidate mass is our main discriminant against combinatorial background. We see no evidence for $B^{\pm }\to h^{\pm }\tau \ell$ decays and set a 90% confidence level upper limit on each branching fraction at the level of a few times ${10}^{-5}$.

We discuss various formulations of null polygons in full, nonchiral $\mathcal{N}=4$ superspace in terms of spacetime, spinor, and twistor variables. We also note that null polygons are necessarily fat along fermionic directions, a curious fact which is compensated by suitable equivalence relations in physical theories on this superspace.

We illustrate with examples that quantum symmetry breakings in perturbation theory are connected to breakdown of momentum routing invariance (MRI) in the loops of a Feynman diagram. We show that MRI is a necessary and sufficient condition to preserve Abelian gauge symmetry at arbitrary loop order. We adopt the implicit regularization framework in which surface terms that are directly connected to momentum routing can be constructed to arbitrary loop order. The interplay between momentum routing invariance, surface terms and anomalies is discussed. We also illustrate that MRI is important to preserve supersymmetry. For theories with poor symmetry content, such as scalar field theories, MRI is shown to be important in the calculation of renormalization group functions.

We present results from a new set of three-dimensional general-relativistic hydrodynamic simulations of rotating iron core collapse. We assume octant symmetry and focus on axisymmetric collapse, bounce, the early postbounce evolution, and the associated gravitational wave (GW) and neutrino signals. We employ a finite-temperature nuclear equation of state, parametrized electron capture in the collapse phase, and a multispecies neutrino leakage scheme after bounce. The latter captures the important effects of deleptonization, neutrino cooling and heating and enables approximate predictions for the neutrino luminosities in the early evolution after core bounce. We consider $12-M_{\odot }$ and $40-M_{\odot }$ presupernova models and systematically study the effects of (i) rotation, (ii) progenitor structure, and (iii) postbounce neutrino leakage on dynamics, GW, and neutrino signals. We demonstrate that the GW signal of rapidly rotating core collapse is practically independent of progenitor mass and precollapse structure. Moreover, we show that the effects of neutrino leakage on the GW signal are strong only in nonrotating or slowly rotating models in which GW emission is not dominated by inner core dynamics. In rapidly rotating cores, core bounce of the centrifugally deformed inner core excites the fundamental quadrupole pulsation mode of the nascent protoneutron star. The ensuing global oscillations ($f\sim 700–800\mathrm{Hz}$) lead to pronounced oscillations in the GW signal and correlated strong variations in the rising luminosities of antineutrino and heavy-lepton neutrinos. We find these features in cores that collapse to protoneutron stars with spin periods $\lesssim 2.5\mathrm{ms}$ and rotational energies sufficient to drive hyperenergetic core-collapse supernova explosions. Hence, GW or neutrino observations of a core-collapse event could deliver strong evidence for or against rapid core rotation. Joint $\mathrm{GW}+\mathrm{\text{neutrino}}$ observations would allow one to make statements with high confidence. Our estimates suggest that the GW signal should be detectable throughout the Milky Way by advanced laser-interferometer GW observatories, but a water-Cherenkov neutrino detector would have to be of near-megaton size to observe the variations in the early neutrino luminosities from a core collapse event at 1 kpc.