We suggest the idea, supported by concrete calculations within chiral models, that the critical end point of the phase diagram of quantum chromodynamics with three colors can be detected, by means of lattice simulations of grand-canonical ensembles with a chiral chemical potential, ${\mu }_5$, conjugated to chiral charge density. In fact, we show that a continuation of the critical end point of the phase diagram of quantum chromodynamics at finite chemical potential, $\mu$, to a critical end point in the temperature-chiral chemical potential plane, is possible. This study paves the way for the mapping of the phases of quantum chromodynamics at finite $\mu$, by means of the phases of a fictitious theory in which $\mu$ is replaced by ${\mu }_5$.

We study a type I seesaw scenario where the right-handed (RH) neutrinos, responsible for the light neutrino mass generation, lie at the electroweak scale. Under certain conditions, the strength of the charged current (CC) and neutral current (NC) weak interactions of the standard model particles with the heavy RH neutrinos can be large enough to allow the production of the latter at the LHC, opening also the possibility of observing other low energy signatures of the new physics in the electroweak precision observables as well as in searches for rare leptonic decays or neutrinoless double beta decay. In this scenario the flavor structure of the indicated CC and NC couplings of the heavy RH neutrinos is essentially determined by the low energy neutrino parameters, leading to fairly strong correlations among the new phenomena. In particular, we show that the present bound on the $\mu \to e+\gamma$ decay rate makes very difficult the observation of the heavy RH neutrinos at the LHC or the observation of deviations from the standard model predictions in the electroweak precision data. We also show that all present experimental constraints on this scenario still allow (i) for an enhancement of the rate of neutrinoless double beta decay, which thus can be in the range of sensitivity of the GERDA experiment even when the light Majorana neutrinos possess a normal hierarchical mass spectrum, and (ii) for the predicted $\mu \to e+\gamma$ decay rate to be within the sensitivity range of the MEG experiment.

Soft-collinear effective theory (SCET) has been formulated since a decade now in covariant gauges. In this work, we derive a modified SCET Lagrangian applicable in both classes of gauges: regular and singular ones. This extends the range of applicability of SCET. The new Lagrangian must be used to obtain factorization theorems in cases where the transverse momenta of the particles in the final states are not integrated over, such as semi-inclusive deep inelastic scattering, Drell-Yan and the Higgs production cross-section at low transverse-momentum. By doing so, all nonperturbative matrix elements appearing in the factorized cross-sections are gauge invariant.

We intrinsically characterize separability of the Dirac equation in Kerr-NUT-(A)dS spacetimes in all dimensions. Namely, we explicitly demonstrate that, in such spacetimes, there exists a complete set of first-order mutually commuting operators, one of which is the Dirac operator, that allows for common eigenfunctions which can be found in a separated form and correspond precisely to the general solution of the Dirac equation found by Oota and Yasui [Phys. Lett. B 659, 688 (2008)]. Since all the operators in the set can be generated from the principal conformal Killing-Yano tensor, this establishes the (up-to-now) missing link among the existence of hidden symmetry, presence of a complete set of commuting operators, and separability of the Dirac equation in these spacetimes.

A new simple and general explanation of the effect of acceleration of particles by black holes to infinite energies in the center of mass frame is suggested. It is based on kinematics of particles moving near the horizon. This effect arises when particles of two kinds collide near the horizon. For massive particles, the first kind represents a particle with the generic energy and angular momentum (I call them “usual”). Near the horizon, such a particle has a velocity almost equal to that of light in the frame that corotates with a black hole (the frame is static if a black hole is static). The second kind (called “critical”) consists of particles with the velocity $v<c$ near the horizon due to special relationship between the energy and angular momentum (or charge). As a result, the relative velocity approaches the speed of light $c$, and the Lorentz factor grows unbound. This explanation applies both to generic rotating black holes and charged ones (even for radial motion of particles). If one of the colliding particles is massless (photon), the critical particle is distinguished by the fact that its frequency is finite near the horizon. The existence (or absence) of the effect is determined depending on competition of two factors—gravitational blue shift for a photon propagating towards a black hole and the Doppler effect due to transformation from the locally nonrotating frame to a comoving one. Classification of all possible types of collisions is suggested depending on whether massive or massless particle is critical or usual.

Probing the dark matter clustering and its evolution with weak lensing surveys constitutes a unique tool to constrain interacting dark energy models. We focus here on weak lensing forecasts from future Euclid and LSST-like surveys combined with the expected results from the ongoing Planck cosmic microwave background satellite experiment. We find that these future data could constrain the dimensionless coupling between dark matter and dark energy to be smaller than a $\mathrm{\text{few}}\times {10}^{-2}$, improving the CMB-only constraint by at least 2 orders of magnitude. We also show that coupled cosmologies can substantially alter the constraints on cosmological parameters obtained from CMB experiments under the assumption of noninteracting cosmologies unless weak lensing data is considered.

Neglected single-photon processes are compared to an excess of electronlike events observed in a predominantly ${\nu }_{\mu }$ beam at MiniBooNE. Predictions are given for analogous events in antineutrino mode.

The Tevatron collaborations have searched for associated production of charginos and neutralinos via trilepton final states. No events above the standard model prediction were observed. We employ these results to put stringent bounds on $R$-parity violating models with a right-handed scalar electron as the lightest supersymmetric particle. We work in the framework of lepton number violating minimal supergravity. We find that within these models, the complete parameter space consistent with the anomalous magnetic moment of the muon can be excluded at 90% confidence level. We also give prospects for Tevatron trilepton searches assuming an integrated luminosity of $10{\mathrm{fb}}^{-1}$. We find that Tevatron will be able to test selectron lightest supersymmetric particle masses up to 170 GeV.

We determine the neutral kaon mixing matrix element $B_K$ in the continuum limit with $2+1$ flavors of domain wall fermions, using the Iwasaki gauge action at two different lattice spacings. These lattice fermions have near exact chiral symmetry and therefore avoid artificial lattice operator mixing. We introduce a significant improvement to the conventional nonperturbative renormalization (NPR) method in which the bare matrix elements are renormalized nonperturbatively in the regularization invariant momentum scheme (RI-MOM) and are then converted into the $\overline{\mathrm{MS}}$ scheme using continuum perturbation theory. In addition to RI-MOM, we introduce and implement four nonexceptional intermediate momentum schemes that suppress infrared nonperturbative uncertainties in the renormalization procedure. We compute the conversion factors relating the matrix elements in this family of regularization invariant symmetric momentum schemes (RI-SMOM) and $\overline{\mathrm{MS}}$ at one-loop order. Comparison of the results obtained using these different intermediate schemes allows for a more reliable estimate of the unknown higher-order contributions and hence for a correspondingly more robust estimate of the systematic error. We also apply a recently proposed approach in which twisted boundary conditions are used to control the Symanzik expansion for off-shell vertex functions leading to a better control of the renormalization in the continuum limit. We control chiral extrapolation errors by considering both the next-to-leading order SU(2) chiral effective theory, and an analytic mass expansion. We obtain $B_K^{\overline{\mathrm{MS}}}(3\mathrm{GeV})=0.529(5{)}_{\mathrm{stat}}(15{)}_{\chi }(2{)}_{\mathrm{FV}}(11{)}_{\mathrm{NPR}}$. This corresponds to ${\widehat{B}}_K^{\overline{\mathrm{RGI}}}=0.749(7{)}_{\mathrm{stat}}(21{)}_{\chi }(3{)}_{\mathrm{FV}}(15{)}_{\mathrm{NPR}}$. Adding all sources of error in quadrature, we obtain ${\widehat{B}}_K^{\overline{\mathrm{RGI}}}=0.749(27{)}_{\mathrm{combined}}$, with an overall combined error of 3.6%.

Parity-violating electron-deuteron scattering can potentially provide a clean access to electroweak couplings that are sensitive to physics beyond the standard model. However, hadronic effects can contaminate their extraction from high-precision measurements. Power-suppressed contributions are one of the main sources of uncertainties along with charge-symmetry violating effects in leading-twist parton densities. In this work we calculate the twist-four correlation functions contributing to the left-right polarization asymmetry making use of nucleon multiparton light-cone wave functions.

The $W$-pair production in association with a massive (anti)bottom jet is not only an important background to a number of interesting processes, such as the single top production associated with a $W$ boson, but also a potential background to new physics searches. We present the calculations of the total and differential cross sections for the $W^{+}{W}^{-}+b(\overline{b})$ jet productions at the LHC up to the QCD next-to-leading order (NLO). Our results by adopting the QCD NLO contribution collection scheme-I show that the K factors can be 1.66 and 1.21 with the inclusive and exclusive two-jet event selection schemes, respectively, when we set $m_H=120\mathrm{GeV}$, $\mu =m_W+m_b/2$ and take the constraints of $p_{T,b(\overline{b})}>25\mathrm{GeV}$, $|y_{b(\overline{b})}|<2.5$ for $b(\overline{b})$ jet. We find that the stabilization of the theoretical prediction for the integrated cross section for the $pp\to W^{+}{W}^{-}b(\overline{b})+X$ up to the QCD NLO requires a veto on a second isolated hard jet and the inclusion of the QCD NLO contribution from the $W^{+}{W}^{-}b\overline{b}(bb,\overline{b}\overline{b})$ production with the final two $b(\overline{b})$ quarks being merged as one jet.

We critically examine uncertainties in parton distribution functions (PDFs) at large $x$ arising from nuclear effects in deuterium $F_2$ structure function data. Within a global PDF analysis, we assess the impact on the PDFs from uncertainties in the deuteron wave function at short distances and nucleon off-shell effects, from the use of relativistic kinematics, and from the use of a less restrictive parametrization of the $d/u$ ratio. We find, in particular, that the $d$-quark and gluon PDFs vary significantly with the choice of nuclear model. We highlight the impact of these uncertainties on the determination of the neutron structure functions, and on $W$ boson production and parton luminosity at the Tevatron and the LHC. Finally, we discuss prospects for new measurements sensitive to the $d$-quark and gluon distributions but insensitive to nuclear corrections.

We propose to study the open charm effects in $e^{+}{e}^{-}\to J/\psi \eta$, $J/\psi {\pi }^0$ and $\varphi {\eta }_c$. We show that the exclusive cross section line shapes of these processes would be strongly affected by the open charm effects. Since the final state light meson productions are through soft gluon radiations, we assume a recognition of this soft process via charmed meson loops at the hadronic level. A unique feature among these three reactions is that the $D{\overline{D}}^{*}+\mathrm{c}.\mathrm{c}.$ open channel is located in a relatively isolated energy, i.e. $\sim 3.876\mathrm{GeV}$, which is sufficiently far away from the known charmonia $\psi (3770)$ and $\psi (4040)$. Therefore, the cross section line shapes of these reactions may provide an opportunity for singling out the open charm effects with relatively well-defined charmonium contributions. In particular, we find that the reaction $e^{+}{e}^{-}\to J/\psi {\pi }^0$ is sensitive to the open charm $D{\overline{D}}^{*}+\mathrm{c}.\mathrm{c}.$ Because of the dominance of the isospin-0 component at the charmonium energy region, we predict an enhanced model-independent cusp effect between the thresholds of $D^0{\overline{D}}^{*0}+\mathrm{c}.\mathrm{c}.$ and $D^{+}{D}^{*-}+\mathrm{c}.\mathrm{c}.$ This study can also help us to understand the $X(3900)$ enhancement recently observed by the Belle Collaboration in $e^{+}{e}^{-}\to D\overline{D}+\mathrm{c}.\mathrm{c}.$

We further explore the consequences of treating the $X(3872)$ meson as a tetraquark bound state by analyzing its one-photon decay $X\to \gamma +J/\psi$ in the framework of our approach developed in previous papers which incorporates quark confinement in an effective way. To introduce electromagnetism we gauge a nonlocal effective Lagrangian describing the interaction of the $X(3872)$ meson with its four constituent quarks by using the $P$-exponential path-independent formalism. We calculate the matrix element of the transition $X\to \gamma +J/\psi$ and prove its gauge invariance. We evaluate the $X\to \gamma +J/\psi$ decay width and the longitudinal/transverse composition of the $J/\psi$ in this decay. For a reasonable value of the size parameter of the $X(3872)$ meson we find consistency with the available experimental data. We also calculate the helicity and multipole amplitudes of the process, and describe how they can be obtained from the covariant transition amplitude by covariant projection.

We present a study of the decays $B^{\pm }\to D{K}^{\pm }$ with $D$ mesons reconstructed in the $K^{+}{\pi }^{-}{\pi }^0$ or $K^{-}{\pi }^{+}{\pi }^0$ final states, where $D$ indicates a $D^0$ or a ${\overline{D}}^0$ meson. Using a sample of $474\times {10}^6$ $B\overline{B}$ pairs collected with the BABAR detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ collider at SLAC, we measure the ratios $R^{\pm }\equiv \frac{\Gamma (B^{\pm }\to [K^{\mp }{\pi }^{\pm }{\pi }^0{]}_D{K}^{\pm })}{\Gamma (B^{\pm }\to [K^{\pm }{\pi }^{\mp }{\pi }^0{]}_D{K}^{\pm })}$. We obtain $R^{+}=(5_{-10}^{+12}(\mathrm{stat}{)}_{-4}^{+2}(\mathrm{syst}))\times {10}^{-3}$ and $R^{-}=({12}_{-10}^{+12}(\mathrm{stat}{)}_{-5}^{+3}(\mathrm{syst}))\times {10}^{-3}$, from which we extract the upper limits at 90% probability: $R^{+}<23\times {10}^{-3}$ and $R^{-}<29\times {10}^{-3}$. Using these measurements, we obtain an upper limit for the ratio $r_B$ of the magnitudes of the $b\to u$ and $b\to c$ amplitudes $r_B<0.13$ at 90% probability.

We present a new measurement of the production cross section $\sigma (p\overline{p}\to ZZ)$ at a center-of-mass energy $\sqrt{s}=1.96\mathrm{TeV}$, obtained from the analysis of the four charged lepton final state ${\ell }^{+}{\ell }^{-}{\ell }^{\prime +}{\ell }^{\prime -}$ ($\ell$, ${\ell }^{\prime }=e$ or $\mu$). We observe ten candidate events with an expected background of $0.37\pm 0.13$ events. The measured cross section $\sigma (p\overline{p}\to ZZ)={1.26}_{-0.37}^{+0.47}(\mathrm{stat})\pm 0.14(\mathrm{syst})\mathrm{pb}$ is in agreement with NLO QCD predictions. This result is combined with a previous result from the $ZZ\to {\ell }^{+}{\ell }^{-}\nu \overline{\nu }$ channel resulting in a combined cross section of $\sigma (p\overline{p}\to ZZ)={1.40}_{-0.37}^{+0.43}(\mathrm{stat})\pm 0.14(\mathrm{syst})\mathrm{pb}$.

The CDMS and EDELWEISS collaborations have combined the results of their direct searches for dark matter using cryogenic germanium detectors. The total data set represents $614\mathrm{kg}·\mathrm{days}$ equivalent exposure. A straightforward method of combination was chosen for its simplicity before data were exchanged between experiments. The results are interpreted in terms of limits on spin-independent weakly interacting, massive particle (WIMP)-nucleon cross section. For a WIMP mass of $90\mathrm{GeV}/{\mathrm{c}}^2$, where this analysis is most sensitive, a cross section of $3.3\times {10}^{-44}{\mathrm{cm}}^2$ is excluded at 90% C.L. At higher WIMP masses, the combination improves the individual limits, by a factor 1.6 above $700\mathrm{GeV}/{\mathrm{c}}^2$. Alternative methods of combining the data provide stronger constraints for some ranges of WIMP masses and weaker constraints for others.

We give a unified overview of the zero temperature phases of compressible quantum matter: i.e., phases in which the expectation value of a globally conserved U(1) density, $\mathcal{Q}$, varies smoothly as a function of parameters. Provided the global U(1) and translational symmetries are unbroken, such phases are expected to have Fermi surfaces, and the Luttinger theorem relates the volumes enclosed by these Fermi surfaces to $⟨\mathcal{Q}⟩$. We survey models of interacting bosons and/or fermions and/or gauge fields which realize such phases. Some phases have Fermi surfaces with the singularities of Landau’s Fermi liquid theory, while other Fermi surfaces have non-Fermi liquid singularities. Compressible phases found in models applicable to condensed-matter systems are argued to also be present in models obtained by applying chemical potentials (and other deformations allowed by the residual symmetry at nonzero chemical potential) to the paradigmatic supersymmetric gauge theories underlying gauge-gravity duality: the Aharony-Bergman-Jafferis-Maldacena model in spatial dimension $d=2$, and the $\mathcal{N}=4$ super Yang-Mills theory in $d=3$.

Hydrodynamics predicts long-lived sound and shear waves. Thermal fluctuations in these waves can lead to the diffusion of momentum density, contributing to the shear viscosity and other transport coefficients. Within viscous hydrodynamics in $3+1$ dimensions, this leads to a positive contribution to the shear viscosity, which is finite but inversely proportional to the microscopic shear viscosity. Therefore the effective infrared viscosity is bounded from below. The contribution to the second-order transport coefficient ${\tau }_{\pi }$ is divergent, which means that second-order relativistic viscous hydrodynamics is inconsistent below some frequency scale. We estimate the importance of each effect for the quark-gluon plasma, finding them to be minor if $\eta /s=0.16$ but important if $\eta /s=0.08$.

An accelerated particle sees the Minkowski vacuum as thermally excited, and the particle moves stochastically due to an interaction with the thermal bath. This interaction fluctuates the particle’s transverse momenta like the Brownian motion in a heat bath. Because of this fluctuating motion, it has been discussed that the accelerated charged particle emits extra radiation (the Unruh radiation [P. Chen and T. Tajima, Phys. Rev. Lett. 83, 256 (1999).]) in addition to the classical Larmor radiation, and experiments are under planning to detect such radiation by using ultrahigh intensity lasers constructed in near future [P. G. Thirolf, D. Habs, A. Henig, D. Jung, D. Kiefer, C. Lang, J. Schreiber1, C. Maia, G. Schaller, R. Schutzhold, and T. Tajima, Eur. Phys. J. D 55, 379 (2009).][http://www.extreme-light-infrastructure.eu/.]. There are, however, counterarguments that the radiation is canceled by an interference effect between the vacuum fluctuation and the fluctuating motion. In fact, in the case of an internal detector where the Heisenberg equation of motion can be solved exactly, there is no additional radiation after the thermalization is completed [D. J. Raine, D. W. Sciama, and P. G. Grove, Proc. R. Soc. Lond. A 435, 205 (1991).][A. Raval, B. L. Hu, and J. Anglin, Phys. Rev. D 53, 7003 (1996).]. In this paper, we revisit the issue in the case of an accelerated charged particle in the scalar-field analog of QED. We prove the equipartition theorem of transverse momenta by investigating a stochastic motion of the particle, and show that the Unruh radiation is partially canceled by an interference effect.