Study on the Energy Dependence of the Source Size of Jets by the HBT Correlation Method in e+e−e^+e^- Collisions

The energy dependence of the source size of jets are studied in detail by the HBT correlation method using Monte Carlo Simulation generator {\sf Jetset7.4} to produce 40,000,000 events of $e^+e^-$ collisions at $\sqrt s = 30$, 50, 70, 91.2, 110, 130, 150 and 170~GeV, respectively. The source size of jets are measured using the HBT correlation method with the indistinguishability of identical final state pions. The average source radii of quark-jets and gluon-jets in $e^+e^-$ collisions are obtained at the end of parton evolvement. It is found that the average source radii of quark-jets are obviously larger than those of gluon-jets and the average source radii measured with $\pi^0$ meson are smaller than those with $\pi^+$ or $\pi^-$ meson

Off-shell photon distribution amplitudes in the low-energy effective theory of QCD

Based on the principle of Lorentz covariance the transition matrix elements from an off-shell photon state to the vacuum are decomposed into the light-cone photon distribution amplitudes (DAs), in which only two transversal DAs survive in the on-shell limit. The eight off-shell light-cone photon DAs corresponding to chiral odd and chiral even up to twist four, and the corresponding coupling constants are studied systematically in the instanton vacuum model of quantum chromodynamics (QCD). The various individual photon DAs multiplied by their corresponding coupling constants are expressed in terms of the correlation functions, which are connected with the spectral densities of an effective quark propagator and then evaluated in the low-energy effective theory derived from the instanton vacuum model of QCD. The explicit analytical expressions and the numerical results for the photon DAs and their coupling constants are given

Novel non-equilibrium phase transition caused by non-linear hadronic-quark phase structure

We consider how the occurrence of first-order phase transitions in non-constant pressure differs from those at constant pressure. The former has shown the non-linear phase structure of mixed matter, which implies a particle number dependence of the binding energies of the two species. If the mixed matter is mixed hadron–quark phase, nucleon outgoing from hadronic phase and ingoing to quark phase probably reduces the system to a non-equilibrium state, in other words, there exists the imbalance of the two phases when deconfinement takes place. This novel non-equilibrium process is very analogous to the nuclear reactions that nuclei emit neutrons and absorb them under appropriate conditions. We present self-consistent thermodynamics in description for the processes and identify the microphysics responsible for the processes. The microphysics is an inevitable consequence of non-linear phase structure instead of the effect of an additional dissipation force. When applying our findings to the neutron star containing mixed hadron–quark matter, it is found that the newly discovered energy release might strongly change the thermal evolution behavior of the star

A Systematic Study of Magnetic Field in Relativistic Heavy-Ion Collisions in the RHIC and LHC Energy Regions

The features of magnetic field in relativistic heavy-ion collisions are systematically studied by using a modified magnetic field model in this paper. The features of magnetic field distributions in the central point are studied in the RHIC and LHC energy regions. We also predict the feature of magnetic fields at LHC <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn fontstyle="italic">900</mn></math> , 2760, and 7000 GeV based on the detailed study at RHIC <math id="M2" xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn fontstyle="italic">62.4</mn></math> , 130, and 200 GeV. The dependencies of the features of magnetic fields on the collision energies, centralities, and collision time are systematically investigated, respectively

Parton shower evolution in medium and nuclear modification of photon-tagged jets in Pb+Pb collisions at the LHC

We study the medium modification of jets correlated with large transverse momentum photons at the LHC via a transport and perturbative QCD hybrid model which incorporates the contributions from both elastic collisions and radiative energy loss experienced by the parton showers. Calculations are performed for the modification of the photon-tagged jet yield, the photon–jet energy imbalance, and the azimuthal distribution of away-side jets. The modifications of photon-tagged jets with different xT=pT,J/pT,γ values are studied and they exhibit different centrality and jet cone size dependences due to traversing different medium lengths and density profiles. We further investigate the influence of the transverse and longitudinal jet transport coefficients on the nuclear modification of photon-tagged jet production and jet shape observables

Phenomenological discriminations of the Yukawa interactions in two-Higgs doublet models with Z2 symmetry

There are four types of two-Higgs doublet models under a discrete Z2 symmetry imposed to avoid tree-level flavor-changing neutral current, i.e. type-I, type-II, type-X, and type-Y models. We investigate the possibility to discriminate the four models in the light of the flavor physics data, including Bs – B¯s mixing, Bs,d→μ+μ- , B→τν and B¯→Xsγ decays, the recent LHC Higgs data, the direct search for charged Higgs at LEP, and the constraints from perturbative unitarity and vacuum stability. After deriving the combined constraints on the Yukawa interaction parameters, we have shown that the correlation between the mass eigenstate rate asymmetry AΔΓ of Bs→μ+μ- and the ratio R=B(Bs→μ+μ-)exp/B(Bs→μ+μ-)SM could be a sensitive probe to discriminate the four models with future precise measurements of the observables in the Bs→μ+μ- decay at LHCb

Conserved charges of black holes in Weyl and Einstein–Gauss–Bonnet gravities

An off-shell generalization of the Abbott–Deser–Tekin (ADT) conserved charge was recently proposed by Kim et al. They achieved this by introducing off-shell Noether currents and potentials. In this paper, we construct the crucial off-shell Noether current by the variation of the Bianchi identity for the expression of EOM, with the help of the property of Killing vector. Our Noether current, which contains an additional term that is just one half of the Lie derivative of a surface term with respect to the Killing vector, takes a different form in comparison with the one in their work. Then we employ the generalized formulation to calculate the quasi-local conserved charges for the most general charged spherically symmetric and the dyonic rotating black holes with AdS asymptotics in four-dimensional conformal Weyl gravity, as well as the charged spherically symmetric black holes in arbitrary dimensional Einstein–Gauss–Bonnet gravity coupled to Maxwell or nonlinear electrodynamics in AdS spacetime. Our results confirm those obtained through other methods in the literature

G-bounce inflation: towards nonsingular inflation cosmology with galileon field

We study a nonsingular bounce inflation model, which can drive the early universe from a contracting phase, bounce into an ordinary inflationary phase, followed by the reheating process. Besides the bounce that avoided the Big-Bang singularity which appears in the standard cosmological scenario, we make use of the Horndesky theory and design the kinetic and potential forms of the lagrangian, so that neither of the two big problems in bouncing cosmology, namely the ghost and the anisotropy problems, will appear. The cosmological perturbations can be generated either in the contracting phase or in the inflationary phase, where in the latter the power spectrum will be scale-invariant and fit the observational data, while in the former the perturbations will have nontrivial features that will be tested by the large scale structure experiments. We also fit our model to the CMB TT power spectrum

Thermodynamics of scalar–tensor theory with non-minimally derivative coupling

With the usual definitions for the entropy and the temperature associated with the apparent horizon, we show that the unified first law on the apparent horizon is equivalent to the Friedmann equation for the scalar–tensor theory with non-minimally derivative coupling. The second law of thermodynamics on the apparent horizon is also satisfied. The results support a deep and fundamental connection between gravitation, thermodynamics, and quantum theory

Entropy bound of horizons for charged and rotating black holes

We revisit the entropy product, entropy sum and other thermodynamic relations of charged and rotating black holes. Based on these relations, we derive the entropy (area) bound for both event horizon and Cauchy horizon. We establish these results for variant class of 4-dimensional charged and rotating black holes in Einstein(–Maxwell) gravity and higher derivative gravity. We also generalize the discussion to black holes with NUT charge. The validity of this formula, which seems to be universal for black holes with two horizons, gives further clue on the crucial role that the thermodynamic relations of multi-horizons play in black hole thermodynamics and understanding the entropy at the microscopic level