Monte Carlo event generators assume that protons split into (uu)-diquarks and d-quarks with a probability of $1/3$ in strong interactions. It is shown in this paper that using a value of $1/6$ for the probability allows one to describe at a semi-quantitative level the NA49 Collaboration data for $p+p\to p+X$ reactions at $158\mathrm{GeV}/\mathrm{c}$. The Fritiof (FTF) model of Geant4 was used to simulate the reactions. The reduced weight of the (uu)-diquarks in protons is expected in the instanton model.

We explore the mass splitting of heavy-light mesons with chiral partner structure in nuclear matter. In our calculation, we employed the heavy hadron chiral perturbation theory with chiral partner structure, and the nuclear matter is constructed by putting Skyrmions from the standard Skyrme model onto the face-centered cubic crystal and regarding the Skyrmion matter as nuclear matter. We find that, although the masses of heavy-light mesons with chiral partner structure are split in matter-free space and the Skyrmion phase, they are degenerated in the half-Skyrmion phase in which the chiral symmetry is restored globally. This observation suggests that the magnitude of the mass splitting of heavy-light mesons with chiral partner structure can be used as a probe of the phase structure of nuclear matter.

We consider collider signatures of the hylogenesis—a variant of the antibaryonic dark matter model. We obtain bounds on the model parameters from results of the first LHC run. Also we suggest several new channels relevant for probing the antibaryonic dark matter at LHC.

Precision measurements of the Higgs boson properties at the LHC provide relevant constraints on possible weak-scale extensions of the Standard Model (SM). In the context of the minimal supersymmetric Standard Model (MSSM) these constraints seem to suggest that all the additional, non-SM-like Higgs bosons should be heavy, with masses larger than about 400 GeV. This article shows that such results do not hold when the theory approaches the conditions for “alignment independent of decoupling,” where the lightest $CP$-even Higgs boson has SM-like tree-level couplings to fermions and gauge bosons, independently of the nonstandard Higgs boson masses. The combination of current bounds from direct Higgs boson searches at the LHC, along with the alignment conditions, have a significant impact on the allowed MSSM parameter space yielding light additional Higgs bosons. In particular, after ensuring the correct mass for the lightest $CP$-even Higgs boson, we find that precision measurements and direct searches are complementary and may soon be able to probe the region of non-SM-like Higgs boson with masses below the top quark pair mass threshold of 350 GeV and low to moderate values of $\tan \beta$.

We present a model-independent interpretation of searches for dark matter annihilation in the Sun using an effective field theory approach. We identify a set of effective operators contributing to spin-dependent scattering of dark matter with protons in the nonrelativistic limit and explore simple new physics models which would give rise to such operators. Using the limits on the spin-dependent scattering cross-section set by the IceCube collaboration in their search for dark matter annihilation in the Sun, we derive limits on effective couplings and corresponding masses of mediating particles. We show that the effective field theory interpretation of the IceCube searches provides constraints on dark matter complementary to those from relic density observations and searches at the LHC. Finally, we discuss the impact of astrophysical uncertainties on our results.

We perform a model-independent, nonperturbative investigation of two-point and three-point finite-volume correlation functions in the energy regime where two-particle states can go on shell. We study three-point functions involving a single incoming particle and an outgoing two-particle state, relevant, for example, for studies of meson decays (e.g., $B^0\to K^{*}{\ell }^{+}{\ell }^{-}\to \pi K{\ell }^{+}{\ell }^{-}$) or meson photo production (e.g., $\pi {\gamma }^{*}\to \pi \pi$). We observe that, while the spectrum solely depends on the on-shell scattering amplitude, the correlation functions also depend on off-shell amplitudes. The main result of this work is a generalization of the Lellouch-Lüscher formula relating matrix elements of currents in finite and infinite spatial volumes. We extend that work by considering a theory with multiple, strongly coupled channels and by accommodating external currents which inject arbitrary four-momentum as well as arbitrary angular momentum. The result is exact up to exponentially suppressed corrections governed by the pion mass times the box size. We also apply our master equation to various examples, including the two processes mentioned above as well as examples where the final state is an admixture of two open channels.

We argue that the recent BESIII data on the cross section for the process $e^{+}{e}^{-}\to {\chi }_{c0}\omega$ in the center-of-mass energy range 4.21–4.42 GeV can be described by the contribution of the known charmoniumlike resonance $\psi (4160)$ with the mass of about 4190 MeV. The value of the coupling in the transition $\psi (4160)\to {\chi }_{c0}\omega$ needed for this mechanism is comparable to that in another known similar transition, ${\chi }_{c0}(2P)\to J/\psi \omega$. The suggested mechanism also naturally explains the relatively small reported value of the cross section for the final states ${\chi }_{c1}\omega$ and ${\chi }_{c2}\omega$ above their respective thresholds.

We apply an analysis method previously developed for the extraction of the strong coupling from the OPAL data to the recently revised ALEPH data for nonstrange hadronic $\tau$ decays. Our analysis yields the values ${\alpha }_s(m_{\tau }^2)=0.296\pm 0.010$ using fixed-order perturbation theory, and ${\alpha }_s(m_{\tau }^2)=0.310\pm 0.014$ using contour-improved perturbation theory. Averaging these values with our previously obtained values from the OPAL data, we find ${\alpha }_s(m_{\tau }^2)=0.303\pm 0.009$ and ${\alpha }_s(m_{\tau }^2)=0.319\pm 0.012$, respectively. We present a critique of the analysis method employed previously, for example in analyses by the ALEPH and OPAL collaborations, and compare it with our own approach. Our conclusion is that nonperturbative effects limit the accuracy with which the strong coupling, an inherently perturbative quantity, can be extracted at energies as low as the $\tau$ mass. Our results further indicate that systematic errors on the determination of the strong coupling from analyses of hadronic $\tau$-decay data have been underestimated in much of the existing literature.

We present a next-to-leading order QCD calculation for the single-inclusive production of collimated jets at hadron colliders, when the jet is defined by maximizing a suitable jet function that depends on the momenta of final-state particles in the event. A jet algorithm of this type was initially proposed by Georgi and subsequently further developed into the class of “$J_{E_T}$ algorithms.” Our calculation establishes the infrared safety of the algorithms at this perturbative order. We derive analytical results for the relevant partonic cross sections. We discuss similarities and differences with respect to jets defined by cone or (anti-)$k_t$ algorithms and present numerical results for the Tevatron and the LHC.

We study how the universal contribution to entanglement entropy in a conformal field theory depends on the entangling region. We show that for a deformed sphere the variation of the universal contribution is quadratic in the deformation amplitude. We generalize these results for Rényi entropies. We obtain an explicit expression for the second order variation of entanglement entropy in the case of a deformed circle in a three-dimensional conformal field theory with a gravity dual. For the same system, we also consider an elliptic entangling region and determine numerically the entanglement entropy as a function of the aspect ratio of the ellipse. Based on these three-dimensional results and Solodukhin’s formula in four dimensions, we conjecture that the sphere minimizes the universal contribution to entanglement entropy in all dimensions.

In this paper we have considered the structure of the nonprojectable Horava-Melby-Thompson gravity to find braneworld scenarios. A relativistic scalar field is considered in the matter sector and we have shown how to reduce the equations of motion to first-order differential equations. In particular, we have studied thick brane solutions of both the dilatonic and Randall-Sundrum types.

Extensive investigations show that ${\mathrm{QED}}_3$ exhibits dynamical fermion mass generation at zero temperature when the fermion flavor $N$ is sufficiently small. However, it seems difficult to extend the theoretical analysis to finite temperature. We study this problem by means of the Dyson-Schwinger equation approach after considering the effect of finite temperature or disorder-induced fermion damping. Under the widely used instantaneous approximation, the dynamical mass displays an infrared divergence in both cases. We then adopt a new approximation that includes an energy-dependent gauge boson propagator and obtain results for dynamical fermion mass that do not contain infrared divergence. The validity of the new approximation is examined by comparing it to the well-established results obtained at zero temperature.

A novel cosmological scenario, capable of generating the observed baryon number at the electroweak scale for very small charge parity violating angles, is presented. The proposed mechanism can be applied in conventional Friedmann-Robertson-Walker cosmology, but becomes extremely efficient due to accretion in the context of early cosmic expansion with high-energy modifications. Assuming that our Universe is a Randall-Sundrum brane, baryon asymmetry can easily be produced by Hawking radiation of very small primordial black holes. The Hawking radiation reheats a spherical region around every black hole to a high temperature and the electroweak symmetry is restored there. A domain wall is formed separating the region with the symmetric vacuum from the asymmetric region where electroweak baryogenesis takes place. First order phase transition is not needed. The black hole’s lifetime is prolonged due to accretion, resulting in strong efficiency of the baryon producing mechanism. The black hole mass range allowed by the mechanism includes masses that are energetically favored to be produced from interactions around the higher dimensional Planck scale.

In this paper we introduce and compute a new transport coefficient for the quark-gluon plasma at very high temperature. This new coefficient ${\sigma }_{\chi e}$, the chiral electric separation effect (CESE) conductivity, quantifies the amount of axial current ${\overrightarrow{J}}_A$ that is generated in response to an externally applied electric field $e\overrightarrow{E}$: ${\overrightarrow{J}}_A={\sigma }_{\chi e}(e\overrightarrow{E})$. Starting with a rather general argument in the kinetic theory framework, we show how a characteristic structure ${\sigma }_{\chi e}\propto \mu {\mu }_5$ emerges, which also indicates the CESE as an anomalous transport effect occurring only in a parity-odd environment with nonzero axial charge density ${\mu }_5\ne 0$. Using the hard-thermal-loop framework, the CESE conductivity for the quark-gluon plasma is found to be ${\sigma }_{\chi e}=(\#)T\frac{{\mathrm{Tr}}_{\mathrm{f}}{Q}_e{Q}_A}{g^4\ln (1/g)}\frac{\mu {\mu }_5}{T^2}$ to the leading-log accuracy with the numerical constant $(\#)$ depending on favor content, e.g., $(\#)=14.5163$ for $u$, $d$ light flavors.

In this paper, we present all $[(d+1)+1]$-dimensional static diagonal vacuum solutions of the nonprojectable Hořava-Lifshitz gravity in the IR limit and show that they give rise to very rich Lifshitz-type structures, depending on the choice of the free parameters of the solutions. These include the Lifshitz space-times with or without hyperscaling violation, Lifshitz solitons, and black holes. Remarkably, even the theory breaks explicitly the Lorentz symmetry and allows generically instantaneous propagations, universal horizons still exist, which serve as one-way membranes for signals moving with any large velocities. In particular, particles even with infinitely large velocities would just move around on these boundaries and would not be able to escape to infinity. Another remarkable feature appearing in the Lifshitz-type space-times is that the dynamical exponent $z$ can take its values only in the ranges $1\le z<2$ for $d\ge 3$ and $1\le z<\infty$ for $d=2$, due to the stability and ghost-free conditions of the theory.

The appearance of the inertial vacuum state in Rindler frame has been extensively studied in the literature, both from the point of view of quantum field theory developed using Rindler foliation and using the response of an Unruh-Dewitt detector. In comparison, less attention has been devoted to the study of inertial nonvacuum states when viewed from the Rindler frame. We provide a comprehensive study of this issue in this paper. We first present a general formalism describing the characterization of arbitrary inertial state (i) when described using an arbitrary foliation and (ii) using the response of an Unruh-DeWitt detector moving along an arbitrary trajectory. This allows us to calculate the mean number of particles in an arbitrary inertial state, when the QFT is described using an arbitrary foliation of spacetime or when the state is probed by a detector moving along an arbitrary trajectory. We use this formalism to explicitly compute the results for the Rindler frame and uniformly accelerated detectors. Any arbitrary inertial state will always have a thermal component in the Rindler frame with additional contributions arising from the nonvacuum nature. We classify the nature of the additional contributions in terms of functions characterizing the inertial state. We establish that for all physically well-behaved normalizable inertial states, the correction terms decrease rapidly with the energy of the Rindler mode so that the high frequency limit is dominated by the thermal noise in any normalizable inertial state. However, inertial states which are not strictly normalizable like, for example, the one-particle state with definite momentum, lead to a constant contribution at all high frequencies in the Rindler frame. We show that a similar behavior arises in the response of the Unruh-DeWitt detector as well. In the case of the detector response, we provide a physical interpretation for the constant contribution at high frequencies in terms of total detection rate of comoving inertial detectors. We also describe two different approaches for defining a transition rate for the Unruh-DeWitt detector, when the two-point function lacks the time translation invariance, and discuss several features of different definitions of transition rates. The implications are discussed.

We set up the construction of generic $(d+2)$-dimensional metrics corresponding to $(d+1)$-dimensional fluids, representing holographically the hydrodynamic regimes of the putative dual theories. We give general seed equilibrium metrics appropriate to generic bulk stress energy tensors and discuss the implications of conformal rescalings of the hypersurface on which the fluid is defined. We then show how to obtain the corresponding hydrodynamic metrics using a relativistic gradient expansion and discuss the integrability conditions of the resulting equations. The stress energy tensors of the resulting fluids, both at and away from equilibrium, satisfy a quadratic constraint. We interpret this constraint in terms of two possible equations of state for the fluid and show that only one of the two equations is physical. We illustrate our discussions with the example of the cutoff anti–de Sitter fluid, for which we find the precise interpretation in terms of deformations of the UV conformal field theory. Finally we discuss the relation between the modern fluid/gravity approach taken in this paper and the earlier membrane paradigm.

We consider constraints on cosmic strings from their emission of Higgs particles, in the case that the strings have a Higgs condensate with amplitude of order the string mass scale, assuming that a fraction of the energy of the condensate can be turned into radiation near cusps. The injection of energy by the decaying Higgs particles affects the light element abundances predicted by standard big-bang nucleosynthesis (BBN) and also contributes to the diffuse gamma-ray background (DGRB) in the Universe today. We examine the two main string scenarios (Nambu-Goto and field theory) and find that the primordial helium and deuterium abundances strongly constrain the string tension and the efficiency of the emission process in the NG scenario, while the strongest BBN constraint in the FT scenario comes from the deuterium abundance. The Fermi-LAT measurement of the DGRB constrains the field theory scenario even more strongly than previously estimated from EGRET data, requiring that the product of the string tension $\mu$ and Newton’s constant $G$ is bounded by $G\mu \lesssim 2.7\times {10}^{-11}{\beta }_{\mathrm{ft}}^{-2}$, where ${\beta }_{\mathrm{ft}}^2$ is the fraction of the strings’ energy going into Higgs particles.

The energy spectrum of cosmic neutrinos, which was recently reported by the IceCube Collaboration, shows a gap between 400 TeV and 1 PeV. An unknown neutrino interaction mediated by a field with a mass of the MeV scale is one of the possible solutions to this gap. We examine whether the leptonic gauge interaction $L_{\mu }-L_{\tau }$ can simultaneously explain the two phenomena in the lepton sector: the gap in the cosmic neutrino spectrum and the unsettled disagreement in the muon anomalous magnetic moment. We illustrate that there remain regions in the model parameter space which account for both of the problems. Our results also provide a hint to the distance to the source of the high-energy cosmic neutrinos.