The effect of chiral imbalance on the QCD phase structure is studied in a framework of Dyson–Schwinger equations. It is found that the chiral phase transition is always a crossover in the $T-{\mu }_5$ plane when $\mu$ is 0 MeV or small values. The trail of the critical endpoints (CEPs) along with the variation of the chiral chemical potential is given. We find that the effect of ${\mu }_5$ is somewhat different from the existing chiral model calculations; namely, the CEP first moves roughly along the phase boundary of $T-\mu$ plane in a smaller $\mu$ direction, as in the chiral model calculations, but turns in the opposite direction to move away from the small chemical potential region, which has never been observed before. In addition, we also discuss the possibility of whether the study at finite temperature and chiral chemical potential can provide some useful information for the detection of the CEP at finite temperature and baryon chemical potential, since the former can be calculated in lattice QCD without the sign problem.

Results of a study of the substructure of the highest transverse momentum ($p_T$) jets observed by the CDF Collaboration are presented. Events containing at least one jet with $p_T>400\mathrm{GeV}/c$ in a sample corresponding to an integrated luminosity of $5.95{\mathrm{fb}}^{-1}$, collected in 1.96 TeV proton-antiproton collisions at the Fermilab Tevatron collider, are selected. A study of the jet mass, angularity, and planar-flow distributions is presented, and the measurements are compared with predictions of perturbative quantum chromodynamics. A search for boosted top-quark production is also described, leading to a 95% confidence level upper limit of 38 fb on the production cross section of top quarks with $p_T>400\mathrm{GeV}/c$.

Compactons are solutions of the equations of motion that behave trivially outside a compact region. In general, the operators describing quantum fluctuations above compactons have singularities. However, we show that despite these singularities, the quantum theory is well defined. As an example, we calculate the one-loop mass shift of a compacton in a model described by a single real scalar field.

We study heterotic Calabi-Yau models with hypercharge flux breaking, where the visible $E_8$ gauge group is directly broken to the standard model group by a nonflat gauge bundle, rather than by a two-step process involving an intermediate grand unified theory and a Wilson line. It is shown that the required alternative $E_8$ embeddings of hypercharge, normalized as required for gauge unification, can be found and we classify these possibilities. However, for all but one of these embeddings we prove a general no-go theorem which asserts that no suitable geometry and vector bundle leading to a standard model spectrum can be found. Intuitively, this happens due to the large number of index conditions which have to be imposed in order to obtain a correct physical spectrum in the absence of an underlying grand unified theory.

Based on the analytical technique the effect of the static magnetic field on the s-wave holographic superconductor with dark matter sector of $U(1)$-gauge field type coupled to the Maxwell field has been examined. In the probe limit, we obtained the mean value of the condensation operator. The nature of the condensate in an external magnetic field as well as the behavior of the critical field close to the transition temperature has been revealed. The obtained upturn of the critical field curves as a function of temperature, both in four and five spacetime dimensions, is a fingerprint of the strong coupling approach.

We investigate multifield signatures of the nonminimally coupled supersymmetric Higgs inflation-type cosmological scenario, focusing on the two-field Higgs-lepton inflation model as a concrete example. This type of inflationary model is realized in a theory beyond the Standard Model embedded in supergravity with a noncanonical Kähler potential. We employ the backward $\delta N$ formalism to compute cosmological observables, including the scalar and tensor power spectra, the spectral indices, the tensor-to-scalar ratio, and the local-type nonlinearity parameter. The trajectory of the inflaton is controlled by the initial conditions of the inflaton as well as by the coefficients in the Kähler potential. We analyze the bispectrum of the primordial fluctuations when the inflaton trajectory deviates from a straight line and obtain constraints on the noncanonical terms of the Kähler potential using the Planck satellite data. Our analysis represents a concrete particle phenomenology-based case study of inflation in which primordial non-Gaussianities can reveal aspects of supergravity.

The LIGO gravitational wave (GW) detectors will begin collecting data in 2015, with Virgo following shortly after. These detectors are expected to reach design sensitivity before the end of the decade, and yield the first direct detection of GWs before then. The use of squeezing has been proposed as a way to reduce the quantum noise without increasing the laser power, and has been successfully tested at one of the LIGO sites and at GEO in Germany. When used in Advanced LIGO without a filter cavity, the squeezer improves the performances of detectors above $\sim 100\mathrm{Hz}$, at the cost of a higher noise floor in the low-frequency regime. Frequency-dependent squeezing, on the other hand, will lower the noise floor throughout the entire band. Squeezing technology will have a twofold impact: it will change the number of expected detections and it will impact the quality of parameter estimation for the detected signals. In this work we consider three different GW detector networks, each utilizing a different type of squeezer—all corresponding to plausible implementations. Using LALInference, a powerful Monte Carlo parameter estimation algorithm, we study how each of these networks estimates the parameters of GW signals emitted by compact binary systems, and compare the results with a baseline advanced LIGO-Virgo network. We find that, even in its simplest implementation, squeezing has a large positive impact: the sky error area of detected signals will shrink by $\sim 30\%$ on average, increasing the chances of finding an electromagnetic counterpart to the GW detection. Similarly, we find that the measurability of tidal deformability parameters for neutron stars in binaries increases by $\sim 30\%$, which could aid in determining the equation of state of neutron stars. The degradation in the measurement of the chirp mass, as a result of the higher low-frequency noise, is shown to be negligible when compared to systematic errors. Implementations of a quantum squeezer coupled with a filter cavity will yield a better overall network sensitivity. They will give less drastic improvements over the baseline network for events of fixed signal-to-noise ratio but greater improvements for identical events.

The effect of isoscalar S-wave multichannel $\pi \pi \to \pi \pi ,K\overline{K},\eta \eta$ scattering is considered in the analysis of decay data of the $\mathrm{\Upsilon }$-mesons. We show that when allowing for the final state interaction contribution to the decays $\mathrm{\Upsilon }(mS)\to \mathrm{\Upsilon }(nS)\pi \pi$ ($m>n,m=2,3,n=1,2$) in our model-independent approach, we can explain the two-pion energetic spectra of these $\mathrm{\Upsilon }$ transitions including the two-humped shape of the di-pion mass distribution in $\mathrm{\Upsilon }(3S)\to \mathrm{\Upsilon }(1S)\pi \pi$ as the coupled-channel effect. It is shown also that the considered bottomia decay data do not offer new insights into the nature of the $f_0$ mesons, which were not already deduced in our previous analyses of pseudoscalar meson scattering data.

The CMS Collaboration has recently reported some excess events in final states with electrons and jets, in searches for leptoquarks and $W^{\prime }$ bosons. Although these excesses may be due to some yet-to-be-understood background mismodeling, it is useful to seek realistic interpretations involving new particles that could generate such events. We show that resonant pair production of vectorlike leptons that decay to an electron and two jets leads to kinematic distributions consistent with the CMS data.

We present a measurement of the electron charge asymmetry in $p\overline{p}\to W+X\to e\nu +X$ events at a center-of-mass energy of 1.96 TeV, using data corresponding to $9.7{\mathrm{fb}}^{-1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. The asymmetry is measured as a function of the electron pseudorapidity and is presented in five kinematic bins based on the electron transverse energy and the missing transverse energy in the event. The measured asymmetry is compared with next-to-leading-order predictions in perturbative quantum chromodynamics and provides accurate information for the determination of parton distribution functions of the proton. This is the most precise lepton charge asymmetry measurement to date.

We present a calculation of next-to-next-to-next-to-leading-order (NNNLO) soft-gluon corrections for differential distributions in top-antitop pair production in hadronic collisions. Approximate NNNLO (aNNNLO) results are obtained from soft-gluon resummation. Theoretical predictions are shown for the top-quark aNNNLO transverse momentum ($p_T$) and rapidity distributions at LHC and Tevatron energies. The aNNNLO corrections enhance previous results for the distributions but have smaller theoretical uncertainties.

We show that the statement in Liu et al. [Phys. Rev. D 86, 064012 (2012)] that the zero mode of Elko spinor is localized in some thin brane scenarios is not correct. This reopens the problem of localization of Elko spinors.

We consider nonlinear massive gravity with two Stückelberg fields in which the diffeomorphism invariance is broken spontaneously in two of the spacetime directions. This theory admits a charged anti–de Sitter black brane solution and has recently been used in the holographic context as a bulk description of a boundary field theory with momentum dissipation. Here we study the stability of the black brane solution. We identify the physical degrees of freedom and determine the healthy regions of the parameter space of the theory. We find that there is a region in parameter space, where the theory suffers from ghost instability. We recognize this as the reason for the instability found in the previous works on holographic conductivity. We also rederive the previous results for the holographic conductivity in a coordinate-independent way.

In this paper, the thermalization has been studied holographically. Explicitly in the gravity side, we consider the gravitational collapse of a thin shell of dust in a spacetime dominated by quintessence dark energy. With the thermalization probes such as the normalized geodesic length and minimal area surface, we study the effect of the state parameter for the quintessence dark energy on the thermalization. Our results show that the smaller the state parameter of quintessence is, the harder the plasma to thermalize. We also investigate the thermalization velocity and thermalization acceleration. We hope our results here can shed light on the nature of the quintessence dark energy.

We study quantum systems of interacting electrons, magnetic monopoles, and electromagnetic field. We formulate a convenient field theory, in which the electron-photon, monopole-photon, and electron-monopole interactions take simple forms.

Closed formulas for tree amplitudes of $n$-particle scatterings of gluon, graviton, and massless scalar particles have been proposed by Cachazo, He, and Yuan. They depend on $(n-3)$ quantities ${\sigma }_{\alpha }$ which satisfy a set of coupled scattering equations, with momentum dot products as input coefficients. These equations are known to have $(n-3)!$ solutions; hence, each ${\sigma }_{\alpha }$ is believed to satisfy a single polynomial equation of degree $(n-3)!$. In this article, we derive the transformation properties of ${\sigma }_{\alpha }$ under momentum permutation and verify them with known solutions at low $n$, and with exact solutions at any $n$ for special momentum configurations. For momentum configurations not invariant under a certain momentum permutation, new solutions can be obtained for the permuted configuration from these symmetry relations. These symmetry relations for ${\sigma }_{\alpha }$ lead to symmetry relations for the $(n-3)!+1$ coefficients of the single-variable polynomials, whose correctness are checked with the known cases at low $n$. The extent to which the coefficient symmetry relations can determine the coefficients is discussed.

A ($3+1$)-dimensional asymptotically flat Kerr black hole angular speed ${\mathrm{\Omega }}_{+}$ can be used to define an effective spring constant, $k=m{\mathrm{\Omega }}_{+}^2$. Its maximum value is the Schwarzschild surface gravity, $k=\kappa$, which rapidly weakens as the black hole spins down and the temperature increases. The Hawking temperature is expressed in terms of the spring constant: $2\pi T=\kappa -k$. Hooke’s law, in the extremal limit, provides the force $F=1/4$, which is consistent with the conjecture of maximum force in general relativity.

Motivated by conformal field theory studies, we investigate quantum Einstein gravity with a new field parametrization where the dynamical metric is basically given by the exponential of a matrix-valued fluctuating field, $g_{\mu \nu }={\overline{g}}_{\mu \rho }(e^h{{)}^{\rho }}_{\nu }$. In this way, we aim to reproduce the critical value of the central charge when considering $2+\epsilon$-dimensional spacetimes. With regard to the asymptotic safety program, we take special care of possible fixed points and new structures of the corresponding RG flow in $d=4$ for both single- and bimetric truncations. Finally, we discuss the issue of restoring background independence in the bimetric setting.

We consider a static self-gravitating perfect fluid system in Lovelock gravity theory. For a spacial region on the hypersurface orthogonal to static Killing vector, by the Tolman’s law of temperature, the assumption of a fixed total particle number inside the spacial region, and all of the variations (of relevant fields) in which the induced metric and its first derivatives are fixed on the boundary of the spacial region, then with the help of the gravitational and fluid equations of the theory, we can prove a theorem says that the total entropy of the fluid in this region takes an extremum value. A converse theorem can also be obtained following the reverse process of our proof. We also propose the definition of isolation quasilocally for the system and explain the physical meaning of the boundary conditions in the proof of the theorems.

We study the thermodynamics and thermodynamic geometry of a five-dimensional Reissner-Nordström-AdS black hole in the extended phase space by treating the cosmological constant as being related to the number of colors in the boundary gauge theory and its conjugate quantity as the associated chemical potential. We find that the contribution of the charge of the black hole to the chemical potential is always positive, and the existence of charge makes the chemical potential become positive more easily. We calculate the scalar curvatures of the thermodynamical Weinhold metric, Ruppeiner metric, and Quevedo metric, respectively, in the fixed $N^2$ case and the fixed $q$ case. We find that in the fixed $N^2$ case, the divergence of the scalar curvature is related to the divergence of the specific heat with fixed electric potential in the Weinhold metric and Ruppeiner metric, and the divergence of the scalar curvature in the Quevedo metric corresponds to the divergence of the specific heat with fixed electric charge density. In the fixed $q$ case, however, the divergence of the scalar curvature is related to the divergence of the specific heat with fixed chemical potential in the Weinhold metric and Ruppeiner metric, while in the Quevedo metric, the divergence of the scalar curvature corresponds to the divergence of the specific heat with a fixed number of colors and the vanishing of the specific heat with a fixed chemical potential.