We study the production of Mueller-Navelet jets at hadron colliders in the Balitsky-Fadin-Kuraev-Lipatov framework. We show that a measurement of the relative azimuthal angle $\Delta \Phi$ between the jets can provide a good testing ground for corrections due to next-leading logarithms (NLL). Besides the well-known azimuthal decorrelation with increasing rapidity interval $\Delta \eta$ between the jets, we propose to also measure this effect as a function of $R=k_2/k_1$, the ratio between the jet transverse momenta. Using renormalization-group improved NLL kernel, we obtain predictions for $d\sigma /d\Delta \eta dRd\Delta \Phi$. We analyze NLL-scheme and renormalization-scale uncertainties, and energy-momentum conservation effects, in order to motivate a measurement at the Tevatron and the LHC.

We formulate the Polyakov-Nambu-Jona-Lasinio model in $0+1$ dimensions. The thermodynamics captured by the partition function yields a bulk pressure, as well as quark susceptibilities versus temperature that are similar to the ones in $3+1$ dimensions. Around the transition temperature the behavior in the pressure and quark susceptibilities follows from the interplay between the lowest Matsubara frequency and the Polyakov line. The reduction to the lowest Matsubara frequency yields a matrix model. In the presence of the Polyakov line the UV part of the Dirac spectrum features oscillations when close to the transition temperature.

The proximity of $Z^{+}(4430)$ to the $D^{*}{\overline{D}}_1$ threshold suggests that it may be a $D^{*}{\overline{D}}_1$ molecular state. The $D^{*}{\overline{D}}_1$ system has been studied dynamically from quark model, and state mixing effect is taken into account by solving the multichannel Schrödinger equation numerically. We suggest the most favorable quantum number is $J^P=0^{-}$, if future experiments confirm $Z^{+}(4430)$ as a loosely bound molecule state. More precise measurements of $Z^{+}(4430)$ mass and width, partial wave analysis are helpful to understand its structure. The analogous heavy flavor mesons $Z_{bb}^{+}$ and $Z_{bc}^{++}$ are studied as well, and the masses predicted in our model are in agreement with the predictions from potential model and QCD sum rule. We further apply our model to the $D{\overline{D}}^{*}$ and $D{D}^{*}$ system. We find the exotic $D{D}^{*}$ bound molecule does not exist, while the $1^{++}$ $D{\overline{D}}^{*}$ bound state solution can be found only if the screening mass $\mu$ is smaller than 0.17 GeV. The state mixing effect between the molecular state and the conventional charmonium should be considered to understand the nature of $X(3872)$.

The very large $K$ factor for Higgs-boson production at hadron colliders is shown to result from enhanced perturbative corrections of the form $(C_A\pi {\alpha }_s{)}^n$, which arise in the analytic continuation of the gluon form factor to timelike momentum transfer. These terms are resummed to all orders in perturbation theory using the renormalization group. After the resummation, the $K$ factor for the production of a light Higgs boson at the LHC is reduced to a value close to 1.3.

The proton-air inelastic cross section (${\sigma }_{p\mathrm{\text{−}}\mathrm{air}}^{\mathrm{inel}}$) is measured at $\sqrt{s}\approx 2\mathrm{TeV}$ at the EAS-TOP extensive air shower experiment by studying the absorption length of cosmic ray proton primaries cascades reaching the maximum development at the observation level. Primary energies, in the region $E_0=(1.5÷2.5)·{10}^{15}\mathrm{eV}$, are selected through the EAS muon number ($N_{\mu }$), and proton originated cascades at maximum development are selected by means of the shower size ($N_e$). The observed absorption length (${\lambda }_{\mathrm{obs}}$) is a convolution of the proton-air interaction length (${\lambda }_{p\mathrm{\text{−}}\mathrm{air}}$) and of the shower and detector fluctuations. The conversion factor $k={\lambda }_{\mathrm{obs}}/{\lambda }_{\mathrm{int}}$ is obtained by means of simulations performed with the CORSIKA code and the QGSJET II and SIBYLL interaction models. The obtained value of the $p$-air inelastic cross section at $\sqrt{s}\approx 2\mathrm{TeV}$ is ${\sigma }_{p\mathrm{\text{−}}\mathrm{air}}^{\mathrm{inel}}=338\pm 21(\mathrm{stat})\pm 19(\mathrm{syst})-28(\mathrm{syst})\mathrm{mb}$. The statistical and systematic uncertainties, as well as the relationships with the $pp$ ($\overline{p}p$) total cross section measurements are discussed.

We present a measurement of the ratio of the $t\overline{t}$ production cross section via gluon-gluon fusion to the total $t\overline{t}$ production cross section in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ at the Tevatron. Using a data sample with an integrated luminosity of $955{\mathrm{pb}}^{-1}$ recorded by the CDF II detector at Fermilab, we select events based on the $t\overline{t}$ decay to $\mathrm{\text{lepton}}+\mathrm{\text{jets}}$. Using an artificial neural network technique we discriminate between $t\overline{t}$ events produced via $q\overline{q}$ annihilation and $gg$ fusion, and find $G_f=\sigma (gg\to t\overline{t})/\sigma (p\overline{p}\to t\overline{t})<0.33$ at the 68% confidence level. This result is combined with a previous measurement to obtain the most stringent measurement of this quantity by CDF to date, $G_f={0.07}_{-0.07}^{+0.15}$.

The gauge polyvalence of a new numerical code is tested, both in harmonic-coordinate simulations (gauge-waves test bed) and in singularity-avoiding coordinates (simple black-hole simulations, either with or without shift). The code is built upon an adjusted first-order flux-conservative version of the Z4 formalism and a recently proposed family of robust finite-difference high-resolution algorithms. An outstanding result is the long-term evolution (up to $1000M$) of a black hole in normal coordinates (zero shift) without excision.

The Bekenstein-Hawking entropy of black holes in Einstein’s theory of gravity is equal to a quarter of the horizon area in units of Newton’s constant. Wald has proposed that in general theories of gravity the entropy of stationary black holes with bifurcate Killing horizons is a Noether charge which is in general different from the Bekenstein-Hawking entropy. We show that the Noether charge entropy is equal to a quarter of the horizon area in units of the effective gravitational coupling on the horizon defined by the coefficient of the kinetic term of a specific metric perturbation polarization on the horizon. We present several explicit examples of static spherically symmetric black holes.

Black-hole–neutron-star (BHNS) binary mergers are candidate engines for generating both short-hard gamma-ray bursts and detectable gravitational waves. Using our most recent conformal thin-sandwich BHNS initial data and our fully general relativistic hydrodynamics code, which is now adaptive mesh refinement capable, we are able to efficiently and accurately simulate these binaries from large separations through inspiral, merger, and ringdown. We evolve the metric using the Baumgarte-Shapiro-Shibata-Nakamura formulation with the standard moving puncture gauge conditions, and handle the hydrodynamics with a high-resolution shock-capturing scheme. We explore the effects of BH spin (aligned and antialigned with the orbital angular momentum) by evolving three sets of initial data with BH:NS mass ratio $q=3$: the data sets are nearly identical, except the BH spin is varied between $a/M_{\mathrm{BH}}=-0.5$ (antialigned), 0.0, and 0.75. The number of orbits before merger increases with $a/M_{\mathrm{BH}}$, as expected. We also study the nonspinning BH case in more detail, varying $q$ between 1, 3, and 5. We calculate gravitational waveforms for the cases we simulate and compare them to binary black-hole waveforms. Only a small disk ($<0.01M_{\odot }$) forms for the antialigned spin case ($a/M_{\mathrm{BH}}=-0.5$) and for the most extreme-mass-ratio case ($q=5$). By contrast, a massive ($M_{\mathrm{disk}}\approx 0.2M_{\odot }$) hot disk forms in the rapidly spinning ($a/M_{\mathrm{BH}}=0.75$) aligned BH case. Such a disk could drive a short-hard gamma-ray burst, possibly by, e.g., producing a copious flux of neutrino-antineutrino pairs.

We provide a detailed analysis of several aspects of the turduckening technique for evolving black holes. At the analytical level we study the constraint propagation for a family of formulations of Einstein’s field equations and identify under what conditions the turducken procedure is rigorously justified and under what conditions constraint violations will propagate to the outside of the black holes. We present high resolution spherically symmetric studies which verify our analytical predictions. Then we present three-dimensional simulations of single distorted black holes using different variations of the turduckening method and also the puncture method. We study the effect that these different methods have on the coordinate conditions, constraint violations, and extracted gravitational waves. We find that the waves agree up to small but nonvanishing differences, caused by escaping superluminal gauge modes. These differences become smaller with increasing detector location.

We study the structures of hybrid stars with leptons at finite temperature under beta equilibrium. For the quark phase, we use the three flavor Nambu–Jona-Lasinio (NJL) model. For the hadron phase, we adopt the nuclear equation of state (EOS) by Shen et al.. This EOS is in the framework of the relativistic mean field theory including the tree body effects. For the hadron-quark phase transition, we impose the bulk Gibbs construction or the Maxwell construction to take into account uncertainties by finite-size effects. We find that the pure quark phase does not appear in stable star cores in all cases. With the phase transition, the maximum masses increase $\sim 10\%$ for high lepton fraction. On the contrary, without the transition, they decrease $\sim 10\%$. We also find that, in the NJL model, the lepton fraction is more important for structures of unstable stars than the temperature. This result is important for many astrophysical phenomena such as the core collapse of massive stars.

In a left-right gauge model of particle interactions, the left-handed fermion doublet $(\nu ,e{)}_L$ is connected to its right-handed counterpart $(n,e{)}_R$ through a scalar bidoublet so that $e_L$ pairs with $e_R$, and ${\nu }_L$ with $n_R$ to form mass terms. Suppose the latter link is severed without affecting the former, then $n_R$ is not the mass partner of ${\nu }_L$, and as we show in this paper, becomes a candidate for dark matter which is relevant for the recent PAMELA and ATIC observations. We accomplish this in a specific nonsupersymmetric model, where a generalized lepton number can be defined, so that $n_R$ and $W_R^{\pm }$ are odd under $R\equiv (-1{)}^{3B+L+2j}$. Fermionic leptoquarks are also predicted.

We demonstrate an exact cancellation of the infrared divergences in the color-singlet quarkyonic matter with the $1/{\overrightarrow{p}}^4$ Coulomb-like confining interaction both in the chiral symmetry broken and restored regimes.

We use QCD sum rules to estimate the leading-order universal form factors describing the semileptonic $B$ decay into orbital excited $D$-wave charmed doublets, including the ($1^{-}$, $2^{-}$) states ($D_1^{*}$, $D_2^{\prime }$) and the ($2^{-}$, $3^{-}$) states ($D_2$, $D_3^{*}$). The decay rates we predict are ${\Gamma }_{B\to D_1^{*}\ell \overline{\nu }}={\Gamma }_{B\to D_2^{\prime }\ell \overline{\nu }}=2.4\times {10}^{-18}\mathrm{GeV}$, ${\Gamma }_{B\to D_2\ell \overline{\nu }}=6.2\times {10}^{-17}\mathrm{GeV}$, and ${\Gamma }_{B\to D_3^{*}\ell \overline{\nu }}=8.6\times {10}^{-17}\mathrm{GeV}$. The branching ratios are $\mathcal{B}(B\to D_1^{*}\ell \overline{\nu })=\mathcal{B}(B\to D_2^{\prime }\ell \overline{\nu })=6.0\times {10}^{-6}$, $\mathcal{B}(B\to D_2\ell \overline{\nu })=1.5\times {10}^{-4}$, and $\mathcal{B}(B\to D_3^{*}\ell \overline{\nu })=2.1\times {10}^{-4}$, respectively.

Dipion transitions of the subthreshold bottomonium levels ${\rm Y}(nS)\to {\rm Y}(n^{\prime }S)\pi \pi$ with $n>n^{\prime }$, $n=2$, 3, 4 $n^{\prime }=1$, 2 are studied in the framework of the chiral decay Lagrangian, derived earlier. The channels $B\overline{B}$, $B{\overline{B}}^{*}+\mathrm{c}.\mathrm{c}.$, $B^{*}{\overline{B}}^{*}$ are considered in the intermediate state and realistic wave functions of ${\rm Y}(nS)$, $B$ and $B^{*}$ are used in the overlap matrix elements. Imposing the Adler zero requirement on the transition matrix element, one obtains 2d and 1d dipion spectra in reasonable agreement with experiment.

We calculate the production of a $W$ boson and a single $b$ jet to next-to-leading order in QCD at the Fermilab Tevatron and the CERN Large Hadron Collider. Both exclusive and inclusive cross sections are presented. We separately consider the cross section for jets containing a single $b$ quark and jets containing a $b\overline{b}$ pair. There are a wide variety of processes that contribute, and it is necessary to include them all in order to have a complete description at both colliders.

Neural network algorithms have been recently applied to construct parton distribution function (PDF) parametrizations which provide an alternative to standard global fitting procedures. In this exploratory study we propose a technique using self-organizing maps (SOMs). SOMs are a class of clustering algorithms based on competitive learning among spatially ordered neurons. Our SOMs are trained on selections of stochastically generated PDF samples. The selection criterion for every optimization iteration is based on the features of the clustered PDFs. Our goal is a fitting procedure that, at variance with the standard neural network approaches, will allow for an increased control of the systematic bias by enabling user interaction in the various stages of the process.

We elucidate how the color neutrality is harmed in the Polyakov Nambu-Jona Lasinio model at finite density within the adopted mean field approximation. Also we point out how usual assumption about the diagonal form of the Wilson loop may fail in the presence of the diquark condensate on several grounds.

The local coupling of two photons to the fundamental quark currents of a hadron gives an energy-independent contribution to the Compton amplitude proportional to the charge squared of the struck quark, a contribution which has no analog in hadron scattering reactions. We show that this local contribution has a real phase and is universal, giving the same contribution for real or virtual Compton scattering for any photon virtuality and skewness at fixed momentum transfer squared $t$. The $t$ dependence of this $J=0$ fixed Regge pole is parameterized by a yet unmeasured even charge-conjugation form factor of the target nucleon. The $t=0$ limit gives an important constraint on the dependence of the nucleon mass on the quark mass through the Weisberger relation. We discuss how this $1/x$ form factor can be extracted from high-energy deeply virtual Compton scattering and examine predictions given by models of the $H$ generalized parton distribution.

We construct the $CP$-odd weak basis invariants from the neutrino mass matrix in a weak basis, in which the charged lepton mass matrix is diagonal, and find the necessary and sufficient conditions for $CP$ conservation. We study the interrelationships between different $CP$-odd weak basis invariants to examine their implications for the Dirac- and Majorana-type $CP$ violating phases for the phenomenologically allowed Frampton-Glashow-Marfatia texture zero structures of the neutrino mass matrix.