We point out that the extra neutralinos and charginos generically appearing in a large class of $E_6$-inspired models lead to distinctive signatures from gluino cascade decays in comparison to those from the minimal supersymmetric standard model (MSSM). These signatures involve longer decay chains, more visible transverse energy, higher multiplicities of jets and leptons, and less missing transverse energy than in the MSSM. These features make the gluino harder to discover for certain types of conventional analyses; for example, in the six-jet channel we show that a 1 TeV MSSM gluino may resemble an 800 GeV $E_6$ gluino. However, the enriched lepton multiplicity provides enhanced 3- and 4-lepton signatures, which are much more suppressed in the case of the MSSM. As an example we analyze various scenarios in the ${\mathrm{E}}_6\mathrm{SSM}$, demonstrating the utility of a $\mathtt{C}\mathtt{a}\mathtt{l}\mathtt{c}\mathtt{H}\mathtt{E}\mathtt{P}$ model that we have now made publicly available on the High Energy Physics Models DataBase. After extensive scans over the parameter space, we focus on representative benchmark points. We perform detailed Monte Carlo analyses, concentrating on the 3-lepton channel at the 7, 8, and 14 TeV Large Hadron Collider for a wide range of gluino masses, and demonstrate that $E_6$-inspired models are clearly distinguishable from the MSSM in gluino cascade decays. We emphasize to the Large Hadron Collider experimental groups that the distinctive features present in gluino cascade decays, such as those discussed here, not only represent a unique footprint of a particular model but also may provide the key to an earlier discovery of supersymmetry.

If the new boson lying in the narrow mass range between 122 and 127 GeV is confirmed to be a Higgs boson, then stability of the electroweak vacuum in a minimal model with a universal extra dimension (mUED) will require a much lower cutoff for the theory than has been envisaged earlier. We show that this low cutoff leads to important changes in much of the minimal model with a universal extra dimension phenomenology studied till now. In particular, prospects for LHC searches for $n=1$ states are rather limited, while resonant $n=2$ states may go completely undetected. Prospects for detection at high energy $e^{+}{e}^{-}$ colliders are less affected.

We present finite temperature solutions describing $N_c$ $D5$ branes wrapped on the $S^2$ of the resolved conifold in the presence of $N_f$ flavor branes sources and their backreaction i.e., $N_f/N_c\sim 1$. In these solutions the dilaton does not blow up at infinity but stabilizes to a finite value. Thus, we can use them to generate new ones with $D5$ and $D3$ charge. The resulting backgrounds are nonextremal versions of the “flavored” resolved deformed conifold. It is tempting to interpret these solutions as gravity duals of finite temperature field theories exhibiting nontrivial phenomena as Seiberg dualities, Higgsing and confinement. However, a first necessary step in this direction is to investigate their stability. We study the specific heat of these new flavored backgrounds and find that they are thermodynamically unstable. Our results on the stability also apply to some of the nonextremal backgrounds with Klebanov-Strassler asymptotics found in the literature.

In Lorentz- and $CPT$-violating effective field theories involving scalar and spinor fields, there exist forms of Lorentz violation that modify only the scalar-spinor Yukawa interaction vertices. These affect low-energy fermion and antifermion scattering processes through modifications to the nonrelativistic Yukawa potentials. The modified potentials involve novel combinations of momentum, spin, and Lorentz-violating background tensors.

In this paper we derive a hierarchy of integral equations from the four-particle-irreducible effective action which have the form of Bethe-Salpeter equations. We show that the vertex functions defined by these equations can be used to truncate the exact renormalization-group flow equations. This truncation has the property that the flow is a total derivative with respect to the flow parameter. We also show that the truncation is equivalent to solving the $n$-particle-irreducible equations of motion. This result establishes a direct connection between two nonperturbative methods.

We consider diagonal matrix elements of local operators between multisoliton states in finite volume in the sine-Gordon model and formulate a conjecture regarding their finite size dependence which is valid up to corrections exponential in the volume. This conjecture extends the results of Pozsgay and Takács which were only valid for diagonal scattering. In order to test the conjecture, we implement a numerical renormalization group improved truncated conformal space approach. The numerical comparisons confirm the conjecture, which is expected to be valid for general integrable field theories. The conjectured formula can be used to evaluate finite temperature one-point and two-point functions using recently developed methods.

We consider homogeneous non-Abelian vector fields with general potential terms in an expanding universe. We find a mechanical analogy with a system of $N$ interacting particles (with $N$ the dimension of the gauge group) moving in three dimensions under the action of a central potential. In the case of bounded and rapid evolution compared to the rate of expansion, we show by making use of a generalization of the virial theorem that for an arbitrary potential and polarization pattern, the average energy-momentum tensor is always diagonal and isotropic despite the intrinsic anisotropic evolution of the vector field. We consider also the case in which a gauge-fixing term is introduced in the action and show that the average equation of state does not depend on such a term. Finally, we extend the results to arbitrary background geometries and show that the average energy-momentum tensor of a rapidly evolving Yang-Mills field is always isotropic and has the perfect fluid form for any locally inertial observer.

This paper presents results of an all-sky search for periodic gravitational waves in the frequency range $[50,1190]\mathrm{Hz}$ and with frequency derivative range of $\sim [-20,1.1]\times {10}^{-10}\mathrm{Hz}{\mathrm{s}}^{-1}$ for the fifth LIGO science run (S5). The search uses a noncoherent Hough-transform method to combine the information from coherent searches on time scales of about one day. Because these searches are very computationally intensive, they have been carried out with the Einstein@Home volunteer distributed computing project. Postprocessing identifies eight candidate signals; deeper follow-up studies rule them out. Hence, since no gravitational wave signals have been found, we report upper limits on the intrinsic gravitational wave strain amplitude $h_0$. For example, in the 0.5 Hz-wide band at 152.5 Hz, we can exclude the presence of signals with $h_0$ greater than $7.6\times {10}^{-25}$ at a 90% confidence level. This search is about a factor 3 more sensitive than the previous Einstein@Home search of early S5 LIGO data.

The recent discovery of a 125 GeV Higgs-like resonance at LHC, coupled with the lack of evidence for weak scale supersymmetry (SUSY), has severely constrained SUSY models such as minimal supergravity (mSUGRA)/CMSSM. As LHC probes deeper into SUSY model parameter space, the little hierarchy problem—how to reconcile the $Z$ and Higgs boson mass scale with the scale of SUSY breaking—will become increasingly exacerbated unless a sparticle signal is found. We evaluate two different measures of fine-tuning in the mSUGRA/CMSSM model. The more stringent of these, ${\Delta }_{\mathrm{HS}}$, includes effects that arise from the high-scale origin of the mSUGRA parameters while the second measure, ${\Delta }_{\mathrm{EW}}$, is determined only by weak scale parameters: hence, it is universal to any model with the same particle spectrum and couplings. Our results incorporate the latest constraints from LHC7 sparticle searches, LHCb limits from $B_s\to {\mu }^{+}{\mu }^{-}$ and also require a light Higgs scalar with $m_h\sim 123–127\mathrm{GeV}$. We present fine-tuning contours in the $m_0$ vs $m_{1/2}$ plane for several sets of $A_0$ and $\tan \beta$ values. We also present results for ${\Delta }_{\mathrm{HS}}$ and ${\Delta }_{\mathrm{EW}}$ from a scan over the entire viable model parameter space. We find a ${\Delta }_{\mathrm{HS}}\gtrsim {10}^3$, or at best 0.1%, fine-tuning. For the less stringent electroweak fine-tuning, we find ${\Delta }_{\mathrm{EW}}\gtrsim {10}^2$, or at best 1%, fine-tuning. Two benchmark points are presented that have the lowest values of ${\Delta }_{\mathrm{HS}}$ and ${\Delta }_{\mathrm{EW}}$. Our results provide a quantitative measure for ascertaining whether or not the remaining mSUGRA/CMSSM model parameter space is excessively fine-tuned and so could provide impetus for considering alternative SUSY models.

We study the gauge dynamics of an SO(4)-gauge theory with two Dirac Wilson fermions transforming according to the vector representation of the gauge group. We determine the lattice phase diagram by locating the strong coupling bulk phase transition line and the zero quark mass line. We present results for the spectrum of the theory obtained at a fixed value of the lattice spacing. In particular we measure the pseudoscalar, vector and axial meson masses. The data are consistent with a chiral symmetry breaking scenario rather than a conformal one. When used to break the electroweak symmetry dynamically the model leads to a natural dark matter candidate.

This paper aims at proving the fundamental role of a relativistic formulation for quarkonia models. We present a completely covariant description of a two-quark system interacting by the Cornell potential with a Breit term describing the hyperfine splitting. Using an appropriate procedure to calculate the Breit correction, we find heavy meson masses in excellent agreement with experimental data. We finally use our approach to describe the light quarks: even by taking average values of the running coupling constant, we prove that covariance properties and hyperfine splitting are sufficient to explain the light meson spectrum and to give a very good agreement with the data.

With the recent measurement of $Z_b(10610)$ and $Z_b(10650)\to B{\overline{B}}^{*}+\mathrm{c}.\mathrm{c}.$ and $B^{*}{\overline{B}}^{*}$, we investigate the transitions from the $Z_b(10610)$ and $Z_b(10650)$ to bottomonium states with emission of a pion via intermediate $B{B}^{*}$ meson loops. The experimental data can be reproduced in this approach with a commonly accepted range of values for the form factor cutoff parameter $\alpha$. The ${\rm Y}(3S)\pi$ decay channels appear to experience obvious threshold effects which can be understood by the property of the loop integrals. By investigating the $\alpha$-dependence of partial decay widths and ratios between different decay channels, we show that the intermediate $B{B}^{*}$ meson loops are crucial for driving the transitions of $Z_b/Z_b^{\prime }\to {\rm Y}(nS)\pi$ with $n=1$, 2, 3, and $h_b(mP)\pi$ with $m=1$ and 2.

The CoGeNT Collaboration has recently published results from a fifteen month data set which indicate an annual modulation in the event rate similar to what is expected from weakly interacting massive particle interactions. It has been suggested that the CoGeNT modulation may actually be caused by other annually modulating phenomena, specifically the flux of atmospheric muons underground or the radon level in the laboratory. We have compared the phase of the CoGeNT data modulation to that of the concurrent atmospheric muon and radon data collected by the MINOS experiment which occupies an adjacent experimental hall in the Soudan Underground Laboratory. The results presented are obtained by performing a shape-free ${\chi }^2$ data-to-data comparison and from a simultaneous fit of the MINOS and CoGeNT data to phase-shifted sinusoidal functions. Both tests indicate that the phase of the CoGeNT modulation is inconsistent with the phases of the MINOS muon and radon modulations at the $3.0\sigma$ level.

We discuss boundary conditions for conformal field theories that preserve the boundary Poincaré invariance. As in the bulk field theories, a question arises whether boundary scale invariance leads to boundary conformal invariance. With unitarity, Cardy’s condition of vanishing momentum flow is necessary for the boundary conformal invariance, but it is not sufficient in general. We show both a proof and a counterexample of the enhancement of boundary conformal invariance in ($1+1$) dimension, which depends on the extra assumption we make. In ($1+2$) dimension, Cardy’s condition is shown to be sufficient. In higher dimensions, we give a perturbative argument in favor of the enhancement based on the boundary $g$-theorem. With the help of the holographic dual recently proposed, we show a holographic proof of the boundary conformal invariance under the assumption of the boundary strict null energy condition, which also gives a sufficient condition for the strong boundary $g$-theorem.

We investigate a peculiar supersymmetry of the pairs of reflectionless quantum mechanical systems described by $n$-soliton potentials of a general form that depends on $n$ scaling and $n$ translation parameters. We show that if all the discrete energy levels of the subsystems are different, the superalgebra, being insensitive to translation parameters, is generated by two supercharges of differential order $2n$, two supercharges of order $2n+1$, and two bosonic integrals of order $2n+1$ composed from Lax integrals of the partners. The exotic supersymmetry undergoes a reduction when $r$ discrete energy levels of one subsystem coincide with any $r$ discrete levels of the partner; the total order of the two independent intertwining generators reduces then to $4n-2r+1$, and the nonlinear superalgebraic structure acquires a dependence on $r$ relative translations. For a complete pairwise coincidence of the scaling parameters which control the energies of the bound states and the transmission scattering amplitudes, the emerging isospectrality is detected by a transmutation of one of the Lax integrals into a bosonic central charge. Within the isospectral class, we reveal a special case giving a new family of finite-gap first order Bogoliubov-de Gennes systems related to the Ablowitz-Kaup-Newell-Segur integrable hierarchy.

We study domain walls and bubble nucleation in a nonrelativistic vector field theory with different longitudinal and transverse speeds of sound. We describe analytical and numerical methods to calculate the orientation-dependent domain-wall tension $\sigma (\theta )$. We then use this tension to calculate the critical bubble shape and show that the tunneling exponent is modified by a factor of sound speed ratio. This implies a big modification in the tunneling rate. The longitudinally oriented domain wall tends to be the heaviest and sometime suffers an instability. It can spontaneously break into zigzag segments. In this case, the critical bubble develops kinks, and its energy, and therefore the tunneling rate, scales with the sound speeds very differently than what would be expected for a smooth bubble.

A scalar quantum field theory defined on a discrete spatial coordinate is examined. The renormalization of the lattice propagator is discussed with an emphasis on the periodic nature of the associated momentum coordinate. The analytic properties of the scattering amplitudes indicate the development of a second branch point on which the branch cut from the optical theorem terminates.

In the absence of symmetry assumptions most numerical relativity simulations adopt Cartesian coordinates. While Cartesian coordinates have some desirable properties, spherical polar coordinates appear better suited for certain applications, including gravitational collapse and supernova simulations. Development of numerical relativity codes in spherical polar coordinates has been hampered by the need to handle the coordinate singularities at the origin and on the axis, for example by careful regularization of the appropriate variables. Assuming spherical symmetry and adopting a covariant version of the Baumgarte-Shapiro-Shibata-Nakamura equations, Montero and Cordero-Carrión recently demonstrated that such a regularization is not necessary when a partially implicit Runge-Kutta method is used for the time evolution of the gravitational fields. Here we report on an implementation of the Baumgarte-Shapiro-Shibata-Nakamura equations in spherical polar coordinates without any symmetry assumptions. Using a partially implicit Runge-Kutta method we obtain stable simulations in three spatial dimensions without the need to regularize the origin or the axis. We perform and discuss a number of tests to assess the stability, accuracy and convergence of the code, namely weak gravitational waves, “hydro-without-hydro” evolutions of spherical and rotating relativistic stars in equilibrium, and single black holes.

A general form of warm inflation with the dissipative coefficient $\Gamma ={\Gamma }_0(\varphi /{\varphi }_0{)}^n(T/{\tau }_0{)}^m$ in loop quantum cosmology is studied. In this case, we obtain conditions for the existence of a warm inflationary attractor in the context of loop quantum cosmology by using the method of stability analysis. The two cases when the dissipative coefficient is independent ($m=0$) and dependent ($m\ne 0$) on temperature are analyzed specifically. In the latter case, we use the new power spectrum which should be used when considering temperature dependence in the dissipative coefficient. We find that the thermal effect is enhanced in the case $m>0$. As in the standard inflation in loop quantum cosmology, we also reach the conclusion that quantum effect leaves a tiny imprint on the cosmic microwave background sky.