The thermodynamic behavior of QCD matter at high temperature is currently studied by lattice QCD theory. The main features are the fast rise of the energy density $ϵ$ around the critical temperature $T_c$ and the large trace anomaly of the energy momentum tensor $⟨{\Theta }_{\mu }^{\mu }⟩=ϵ-3P$, which hints at a strongly interacting system. Such features can be accounted for by employing a massive quasiparticle model with a temperature-dependent bag constant. Recent lattice QCD calculations with physical quark masses by the Wuppertal-Budapest group show a slower increase of $ϵ$ and a smaller $⟨{\Theta }_{\mu }^{\mu }⟩$ peak with respect to previous results from the HotQCD Collaboration. We investigate the implications of such differences from the point of view of a quasiparticle model, also discussing light and strange quark number susceptibilities. Furthermore, we predict the impact of these discrepancies on the temperature dependence of the transport properties of matter, like the shear and bulk viscosities.

We propose a unique mechanism called initial single pion emission existing in the ${\rm Y}(5S)$ decays, and further study the line shapes of $d\Gamma ({\rm Y}(5S\to {\rm Y}(nS){\pi }^{+}{\pi }^{-}))/d{m}_{{\rm Y}(nS){\pi }^{+}}$ ($n=1,2,3$) and $d\Gamma ({\rm Y}(5S\to h_b(mP){\pi }^{+}{\pi }^{-}))/d{m}_{h_b(mP){\pi }^{+}}$ ($m=1,2$). We find sharp structures around 10 610 MeV and 10 650 MeV in the obtained theoretical line shapes of $d\Gamma ({\rm Y}(5S\to {\rm Y}(nS){\pi }^{+}{\pi }^{-}))/d{m}_{{\rm Y}(nS){\pi }^{+}}$ and $d\Gamma ({\rm Y}(5S\to h_b(mP){\pi }^{+}{\pi }^{-}))/d{m}_{h_b(mP){\pi }^{+}}$ distributions, which could naturally correspond to the $Z_b(10610)$ and $Z_b(10650)$ structures newly observed by Belle.

We present a search for associated Higgs boson production in the process $p\overline{p}\to W/ZH\to {\ell }^{\pm }{\ell }^{\prime \pm }+X$ in $ee$, $e\mu$, and $\mu \mu$ final states. The search is based on data collected by the D0 experiment at the Fermilab Tevatron Collider at $\sqrt{s}=1.96\mathrm{TeV}$ corresponding to $5.3{\mathrm{fb}}^{-1}$ of integrated luminosity. We require two isolated leptons (electrons or muons) with the same electric charge and additional kinematic requirements. No significant excess above background is observed, and we set 95% C.L. observed (expected) upper limits on ratio of the production cross section to the standard model prediction of 6.4 (7.3) for a Higgs boson mass of 165 GeV and 13.5 (19.8) for a mass of 115 GeV.

We draw the three-flavor phase diagram as a function of light- and strange-quark masses for both zero and imaginary quark-number chemical potential, using the Polyakov-loop extended Nambu–Jona-Lasinio model with an effective four-quark vertex depending on the Polyakov loop. The model prediction is qualitatively consistent with $2+1$ flavor lattice QCD prediction at zero chemical potential and with degenerate three-flavor lattice QCD prediction at imaginary chemical potential.

Using the superfield formalism, the effective Kählerian superpotential of the massless $\mathcal{N}=1$ $O(N)$ Wess-Zumino model is computed in the limit of large $N$, in three spacetime dimensions. The effective Kählerian superpotential is evaluated at the subleading order in the $1/N$ expansion, which involves diagrams up to two-loop order, for a small coupling constant. We show that the $O(N)$ symmetry of the model is preserved in this approximation and that no mass is dynamically generated in the supersymmetric phase. We discuss why spontaneous $O(N)$ symmetry breaking cannot be induced by radiative corrections in such a model.

We study the quantum measurement problem in the context of an infinite, statistically uniform space, as could be generated by eternal inflation. It has recently been argued that when identical copies of a quantum measurement system exist, the standard projection operators and Born rule method for calculating probabilities must be supplemented by estimates of relative frequencies of observers. We argue that an infinite space actually renders the Born rule redundant, by physically realizing all outcomes of a quantum measurement in different regions, with relative frequencies given by the square of the wave-function amplitudes. Our formal argument hinges on properties of what we term the quantum confusion operator, which projects onto the Hilbert subspace where the Born rule fails, and we comment on its relation to the oft-discussed quantum frequency operator. This analysis unifies the classical and quantum levels of parallel universes that have been discussed in the literature, and has implications for several issues in quantum measurement theory. Replacing the standard hypothetical ensemble of measurements repeated ad infinitum by a concrete decohered spatial collection of experiments carried out in different distant regions of space provides a natural context for a statistical interpretation of quantum mechanics. It also shows how, even for a single measurement, probabilities may be interpreted as relative frequencies in unitary (Everettian) quantum mechanics. We also argue that after discarding a zero-norm part of the wave function, the remainder consists of a superposition of indistinguishable terms, so that arguably “collapse” of the wave function is irrelevant, and the “many worlds” of Everett’s interpretation are unified into one. Finally, the analysis suggests a “cosmological interpretation” of quantum theory in which the wave function describes the actual spatial collection of identical quantum systems, and quantum uncertainty is attributable to the observer’s inability to self-locate in this collection.

We study critical black-hole separations for the formation of a common apparent horizon in systems of $N$ black holes in a time-symmetric configuration. We study in detail the aligned equal mass cases for $N=2$, 3, 4, 5, 6, and relate them to the unequal mass binary black-hole case. We then study the apparent horizon of the time-symmetric initial geometry of a ring singularity of different radii. The apparent horizon is used as indicative of the location of the event horizon in an effort to predict a critical ring radius that would generate an event horizon of toroidal topology. We found that a good estimate for this ring critical radius is $20/(3\pi )M$. We briefly discuss the connection of this two cases through a discrete black-hole “necklace” configuration.

In this article, we investigate the assumption of equipartition of energy in arguments for the entropic nature of gravity. It has already been pointed out by other authors that equipartition is not valid for low temperatures. Here we additionally point out that it is similarly not valid for systems with bounded energy. Many explanations for black hole entropy suggest that the microscopic systems responsible have a finite dimensional state space, and thus finite maximum energy. Assuming this to be the case leads to drastic corrections to Newton’s law for high gravitational fields, and, in particular, to a singularity in acceleration at finite radius away from a point mass. This is suggestive of the physics at the Schwarzschild radius. We show, however, that the location of the singularity scales differently.

The dimensional reduction of (the bosonic sector of) five-dimensional minimal supergravity to four dimensions leads to a theory with a massless axion and a dilaton coupled to gravity and two $U(1)$ gauge fields (one of which has Chern-Simons coupling), whose field equations have $SL(2,R)$ invariance. Utilizing this $SL(2,R)$-duality, we provide a new formalism for solution generation. As an example, applying it to the Rasheed solutions, which are known to describe dyonic rotating black holes (from the four-dimensional point of view) of five-dimensional pure gravity, we obtain rotating Kaluza-Klein black hole solutions in five-dimensional minimal supergravity. We also show that the solutions have six charges: mass, angular momentum, Kaluza-Klein electric/magnetic charges and electric/magnetic charges of the Maxwell field, four of which are related by a constraint.

Projection tends to skew the mass-observable relation of galaxy clusters by creating a small fraction of severely blended systems, those for which the measured observable property of a cluster is strongly boosted relative to the value of its primary host halo. We examine the bias in cosmological parameter estimates caused by incorrectly assuming a Gaussian (projection-free) mass-observable relation when the true relation is non-Gaussian due to projection. We introduce a mixture model for projection and explore Fisher forecasts for a survey of $5000{\mathrm{deg}}^2$ to $z=1.1$ and an equivalent mass threshold of ${10}^{13.7}{h}^{-1}{M}_{\odot }$. Using a blended fraction motivated by optical cluster finding applied to the millennium simulation, and applying Planck and otherwise weak priors, we find that the biases in ${\Omega }_{\mathrm{DE}}$ and $w$ are significant, being factors of 2.8 and 2.4, respectively, times previous forecast uncertainties. Incorporating 8 new degrees of freedom to describe cluster selection with projection increases the forecast uncertainty in ${\Omega }_{\mathrm{DE}}$ and $w$ by similar factors. Knowledge of these additional parameters at the 5% level limits degradation in dark energy constraints to $\lesssim 10\%$ relative to projection-free forecasts. We discuss strategies for using simulations and complementary observations to characterize the fraction of blended clusters and their mass-selection properties.

The standard model Higgs sector, extended by one weak gauge triplet of scalar fields with a very small vacuum expectation value, is a very promising setting to account for neutrino masses through the so-called type II seesaw mechanism. In this paper we consider the general renormalizable doublet/triplet Higgs potential of this model. We perform a detailed study of its main dynamical features that depend on five dimensionless couplings and two mass parameters after spontaneous symmetry breaking, and highlight the implications for the Higgs phenomenology. In particular, we determine (i) the complete set of tree-level unitarity constraints on the couplings of the potential and (ii) the exact tree-level boundedness from below constraints on these couplings, valid for all directions. When combined, these constraints delineate precisely the theoretically allowed parameter space domain within our perturbative approximation. Among the seven physical Higgs states of this model, the mass of the lighter (heavier) ${\mathcal{C}\mathcal{P}}_{\mathrm{even}}$ state $h^0$ ($H^0$) will always satisfy a theoretical upper (lower) bound that is reached for a critical value ${\mu }_c$ of $\mu$ (the mass parameter controlling triple couplings among the doublet/triplet Higgses). Saturating the unitarity bounds, we find an upper bound $m_{h^0}<\mathcal{O}(0.7–1\mathrm{TeV})$, while the upper bound for the remaining Higgses lies in the range of several tens of TeV. However, the actual masses can be much lighter. We identify two regimes corresponding to $\mu \gtrsim {\mu }_c$ and $\mu \lesssim {\mu }_c$. In the first regime the Higgs sector is typically very heavy, and only $h^0$ that becomes SM-like could be accessible to the LHC. In contrast, in the second regime, somewhat overlooked in the literature, most of the Higgs sector is light. In particular, the heaviest state $H^0$ becomes SM-like, the lighter states being the ${\mathcal{C}\mathcal{P}}_{\mathrm{odd}}$ Higgs, the (doubly) charged Higgses, and a decoupled $h^0$, possibly leading to a distinctive phenomenology at the colliders.

Arguably the best-motivated channel for early LHC discovery is events including a high multiplicity of third generation quarks, such as four top quarks. For example generic string theories compactified to four dimensions with stabilized moduli typically have light gluinos with large branching ratios to $t$- and $b$-quarks. We analyze signals and background at 7 TeV LHC energy for $1{\mathrm{fb}}^{-1}$ integrated luminosity, suggesting a reach for gluinos of about 650 GeV. A non-standard model signal from counting $b$-jets and leptons is robust, and provides information on the gluino mass, cross section, and spin.

Under $R$ parity, the lightest supersymmetric particle (LSP) is stable and may serve as a good dark matter candidate. The $R$ parity can be naturally introduced with a gauge origin at the TeV scale. We go over why a TeV scale $B-L$ gauge extension of the minimal supersymmetric standard model is one of the most natural, if not demanded, low energy supersymmetric models. In the presence of a TeV scale Abelian gauge symmetry, the (predominantly) right-handed sneutrino LSP can be a good dark matter candidate. Its identification at the LHC is challenging because it does not carry any standard model charge. We show how we can use the correlation between the LHC experiments (dilepton resonance signals) and the direct dark matter search experiments (such as CDMS and XENON) to identify the right-handed sneutrino LSP dark matter in the $B-L$ extended minimal supersymmetric standard model.

We study the Fermi-level structure of $2+1$-dimensional strongly interacting electron systems in external magnetic field using the gague/gravity duality correspondence. The gravity dual of a finite density fermion system is a Dirac field in the background of the dyonic AdS-Reissner-Nordström black hole. In the probe limit, the magnetic system can be reduced to the nonmagnetic one, with Landau-quantized momenta and rescaled thermodynamical variables. We find that at strong enough magnetic fields, the Fermi surface vanishes and the quasiparticle is lost either through a crossover to conformal regime or through a phase transition to an unstable Fermi surface. In the latter case, the vanishing Fermi velocity at the critical magnetic field triggers the non-Fermi-liquid regime with unstable quasiparticles and a change in transport properties of the system. We associate it with a metal–”strange-metal” phase transition. Next, we compute the DC Hall and longitudinal conductivities using the gravity-dressed fermion propagators. For dual fermions with a large charge, many different Fermi surfaces contribute and the Hall conductivity is quantized as expected for integer quantum Hall effect (QHE). At strong magnetic fields, as additional Fermi surfaces open up, new plateaus typical for the fractional QHE appear. The somewhat irregular pattern in the length of fractional QHE plateaus resembles the outcomes of experiments on thin graphite in a strong magnetic field. Finally, motivated by the absence of the sign problem in holography, we suggest a lattice approach to the AdS calculations of finite density systems.

We explore some aspects of holographic dual of Boundary Conformal Field Theory (BCFT). In particular we study asymptotic symmetry of geometries which provide holographic dual of BCFTs. We also compute two-point functions of certain bosonic and fermionic operators in the dual BCFT by making use of AdS/BCFT correspondence.

The circle compactification of the 6-dimensional (2,0) superconformal theory of $A_{N-1}$ type leads to the 5-dimensional $SU(N)$ maximally supersymmetric gauge theory. Instanton solitons embody Kaluza-Klein modes and are conjectured to be composed of partonic constituents. We realize such a parton of $1/N$ instanton topological charge at the intersection of magnetic flux sheets. After a further compactification with nontrivial Wilson-line expectation value, instantons or calorons have been shown to be split into fundamental monopoles of fractional instanton charge. In the symmetric phase with trivial Wilson-line expectation value, Bogomol’nyi–Prasad–Sommerfield instanton partons emerge more concretely as non-Abelian Bogomol’nyi–Prasad–Sommerfield monopoles of minimum charge allowed in Dirac quantization.

In this work, studying systems of two coupled fields in $(1+1)D$, which present kinklike solutions, we introduce an orbit equation deformation procedure. We apply it in cases which present periodic behavior in the fields potential. We build new periodic potentials using this method.

We study dynamical surface gravity in a general spherically symmetric setting using Painlevé-Gullstrand coordinates. Our analysis includes several definitions that have been proposed in the past as well as two new definitions adapted to Painlevé-Gullstrand coordinates. Various properties are considered, including general covariance, value at extremality, locality and static limit. We illustrate with specific examples of “dirty” black holes that even for spacetimes possessing a global timelike Killing vector, local definitions of surface gravity can differ substantially from “nonlocal” ones that require an asymptotic normalization condition. Finally, we present numerical calculations of dynamical surface gravity for black hole formation via spherically symmetric scalar field collapse. Our results highlight the differences between the various definitions in a dynamical setting and provide further insight into the distinction between local and nonlocal definitions of surface gravity.