Electroweak radiative corrections are computed for Higgs production through vector boson fusion, $qq\to qqH$, which is one of the most promising channels for detecting and studying the Higgs boson at the LHC. Using soft-collinear effective theory, we obtain numerical results for the resummed logarithmic contributions to the hadronic cross section at next-to-leading logarithmic order. We compare our results to HAWK and find good agreement below 2 TeV where the logarithms do not dominate. The soft-collinear effective theory method is at its best in the high LHC energy domain where the corrections are found to be slightly larger than predicted by HAWK and by other one-loop fixed order approximations. This is one of the first tests of this formalism at the level of a hadronic cross section, and demonstrates the viability of obtaining electroweak corrections for generic processes without the need for difficult electroweak loop calculations.

In a previous paper [P. Dey and S. Roy, J. High Energy Phys. 06 (2012) 129] we have shown how Lifshitz-like space-times (space-times having Lifshitz scaling with hyperscaling violation) arise from $1/4$ Bogomol’nyi-Prasad-Sommerfield, threshold $\mathrm{F}-\mathrm{D}p$–bound state solutions of type II string theories in the near horizon limit. In this paper we show that similar structures also arise from the near horizon limit of $1/4$ Bogomol’nyi-Prasad-Sommerfield, threshold-intersecting D-brane solutions of type II string theories. Some of these solutions are standard ($\mathrm{D}p-\mathrm{D}(p+4)$ for $p=0$, 2) and some are nonstandard ($\mathrm{D}p-\mathrm{D}(p+2)$ for $p=1$, 2, 3), including $\mathrm{D}2-\mathrm{D}{2}^{\prime }$, $\mathrm{D}3-\mathrm{D}{3}^{\prime }$, and $\mathrm{D}4-\mathrm{D}{4}^{\prime }$ solutions. The dilatons of these solutions, in general, run (except in D2-D4 and $\mathrm{D}3-\mathrm{D}{3}^{\prime }$ cases) and produce renormalization group flows. We discuss the phase structures of these solutions. D2-D4 and $\mathrm{D}3-\mathrm{D}{3}^{\prime }$ in the near horizon limit do not produce Lifshitz-like space-time but give ${\mathrm{AdS}}_3$ spaces.

We propose a scenario with a fermion dark matter, where the dark matter particle used to be the Dirac fermion, but it takes the form of the Majorana fermion at a late time. The relic number density of the dark matter is determined by the dark matter asymmetry generated through the same mechanism as leptogenesis when the dark matter was the Dirac fermion. After efficient dark matter annihilation processes have frozen-out, a phase transition of a scalar field takes place and generates Majorana mass terms to turn the dark matter particle into the Majorana fermion. In order to address this scenario in detail, we propose two simple models. The first one is based on the Standard Model (SM) gauge group and the dark matter originates the $SU(2{)}_L$ doublet Dirac fermion, analogous to the Higgsino-like neutralino in supersymmetric models. We estimate the spin-independent/dependent elastic scattering cross sections of this late-time Majorana dark matter with a proton and find the possibility to discover it by the direct and/or indirect dark matter search experiments in the near future. The second model is based on the $B\mathrm{\text{−}}L$ gauged extension of the SM, where the dark matter is a SM singlet. Although this model is similar to the so-called Higgs portal dark matter scenario, the spin-independent elastic scattering cross section can be large enough to detect this dark matter in future experiments.

While dark matter (DM) is the key ingredient for a successful theory of structure formation, its microscopic nature remains elusive. Indirect detection may provide a powerful test for some strongly motivated DM particle models. Nevertheless, astrophysical backgrounds are usually expected with amplitudes and spectral features similar to the chased signals. On galactic scales, these backgrounds arise from interactions of cosmic rays (CRs) with the interstellar gas, both being difficult to infer and model in detail from observations. Moreover, the associated predictions unavoidably come with theoretical errors, which are known to be significant. We show that a trustworthy guide for such challenging searches can be obtained by exploiting the full information contained in cosmological simulations of galaxies, which now include baryonic gas dynamics and star formation. We further insert CR production and transport from the identified supernova events and fully calculate the CR distribution in a simulated galaxy. We focus on diffuse gamma rays, and self-consistently calculate both the astrophysical galactic emission and the DM signal. We notably show that adiabatic contraction does not necessarily induce large signal-to-noise ratios in galactic centers, and could anyway be traced from the astrophysical background itself. We finally discuss how all this may be used as a generic diagnostic tool for galaxy formation.

We propose an extension of the $4+1$-dimensional $SU(5)$ domain-wall braneworld of Davies, George and Volkas which includes the addition of a discrete $A_4$ flavor symmetry. We show that lepton mixing and light Majorana neutrino masses can be generated from the additional $A_4$ physics while at the same time sufficient parameter freedom can be maintained in the charged fermion sector to produce charged fermion masses and quark mixing naturally from the split fermion mechanism. Importantly, we show that the vacuum realignment problem typical of discrete flavor symmetry models of quark and lepton mixing can be solved by separating the appropriate flavons in the extra dimension, leading to exponentially sensitive suppression of the operators responsible for vacuum realignment.

It is well known that new physics can contribute to weak decays of heavy mesons via virtual processes during its decays. The discovery of new physics, using such decays is made difficult due to intractable strong interaction effects needed to describe it. Modes such as $B\to K^{*}{\ell }^{+}{\ell }^{-}$ offer an advantage as they provide a multitude of observables via angular analysis. We show how the multitude of “related observables” obtained from $B\to K^{*}{\ell }^{+}{\ell }^{-}$, can provide many new “clean tests” of the standard model. The hallmark of these tests is that several of them are independent of the unknown universal form factors that describe the decay in heavy quark effective theory. We derive a relation between observables that is free of form factors and Wilson coefficients, the violation of which will be an unambiguous signal of new physics. We also derive relations between observables and form factors that are independent of Wilson coefficients and enable verification of hadronic estimates. We show how form factor ratios can be measured directly from helicity fraction with out any assumptions what so ever. We find that the allowed parameter space for observables is very tightly constrained in standard model, thereby providing clean signals of new physics. We examine in detail both the large-recoil and low-recoil regions of the $K^{*}$ meson and point out special features and derive relations between observables valid in the two limits. In the large-recoil regions several of the relations are unaffected by corrections to all orders in ${\alpha }_s$. We present yet another new relation involving only observables that would verify the validity of the relations between form factors assumed in the low-recoil region. The several relations and constraints derived will provide unambiguous signals of new physics if it contributes to these decays.

The mixing of the imaginary parts of the transition amplitudes of nearby resonances via the breakdown of the Breit-Wigner approximation has been shown to lead to potentially large modifications in the signal rates for new physics at colliders. In the case of suppression, this effect may be significant enough to lead to some new physics signatures being initially missed in searches at, e.g., the LHC. Here, we explore the influence of this “width mixing” on the production of the nearly degenerate level-2 Kaluza-Klein neutral gauge bosons present in split universal extra dimensions. We demonstrate that, in this particular case, large cross-section modifications in the resonance region are necessarily absent and explain why this is so based on the group theoretical structure of the standard model.

We consider a model based on the supersymmetric QCD theory with $N_c=2$ and $N_f=3$. The theory is strongly coupled at the infrared scale ${\Lambda }_H$. Its low-energy effective theory below ${\Lambda }_H$ is described by the supersymmetric standard model with the Higgs sector that contains four isospin doublets, two neutral isospin singlets and two charged isospin singlets. If ${\Lambda }_H$ is at the multi-TeV to 10 TeV, coupling constants for the F terms of these composite fields are relatively large at the electroweak scale. Nevertheless, the standard model-like Higgs boson is predicted to be as light as 125 GeV because these F terms contribute to the mass of the standard model-like Higgs boson not at the tree level but at the one-loop level. A large nondecoupling effect due to these F terms appears in the one-loop correction to the triple Higgs boson coupling, which amounts to a few tens percent. Such a nondecoupling property in the Higgs potential realizes the strong first-order phase transition, which is required for a successful scenario of electroweak baryogenesis.

We present an update of the $D$ meson decay constant $f_D$ using the highly improved staggered quark action for valence charm and light quarks on MILC $N_f=2+1$ lattices. The new determination incorporates HPQCD’s improved scale $r_1^{N_f=2+1}=0.3133(23)\mathrm{fm}$, accurately retuned bare charm quark masses and data from an ensemble that is more chiral than in our previous calculations. We find $f_D=208.3(3.4)\mathrm{MeV}$. Combining the new $f_D$ with $D\to \mu {\nu }_{\mu }$ branching fraction data from CLEO-c, we extract the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cd}|=0.223(10{)}_{\exp }(4{)}_{\mathrm{lat}}$. This value is in excellent agreement with $|V_{cd}|$ from $D$ semileptonic decays and from neutrino scattering experiments and has comparable total errors. We determine the ratio between semileptonic form factor and decay constant and find $[f_{+}^{D\to \pi }(0)/f_D{]}_{\mathrm{lat}}=3.20(15){\mathrm{GeV}}^{-1}$ to be compared with the experimental value of $[f_{+}^{D\to \pi }(0)/f_D{]}_{\exp }=3.19(18){\mathrm{GeV}}^{-1}$. Finally, we mention recent preliminary but already more accurate $D\to \mu {\nu }_{\mu }$ branching fraction measurements from BES III and discuss their impact on precision $|V_{cd}|$ determinations in the future.

We consider a class of parity-even, six-derivative gravity theories in three dimensions. After linearizing around anti–de Sitter space, the theories have one massless and two massive graviton solutions for generic values of the parameters. At a special, so-called tricritical, point in parameter space the two massive graviton solutions become massless, and they are replaced by two solutions with logarithmic and logarithmic-squared boundary behavior. The theory at this point is conjectured to be dual to a rank-3 logarithmic conformal field theory whose boundary stress tensor, central charges, and new anomaly we calculate. We also calculate the conserved Abbott-Deser-Tekin charges. At the tricritical point, these vanish for excitations that obey Brown-Henneaux and logarithmic boundary conditions, while they are generically nonzero for excitations that show logarithmic-squared boundary behavior. This suggests that a truncation of the tricritical gravity theory and its corresponding dual logarithmic conformal field theory can be realized either via boundary conditions on the allowed gravitational excitations, or via restriction to a zero-charge subsector. We comment on the structure of the truncated theory.

We find a gravitational instanton that connects an initial state corresponding to a single-centered extremal Reissner-Nordstrom black hole configuration, to a final state corresponding to a multicentered configuration. This instanton is interpreted as describing quantum tunneling between the two different black hole solutions. We evaluate the Euclidean action for this instanton and find that the amplitude for the tunneling process is equal to half the difference in entropy between the initial and final configurations.

In single field inflationary models, preheating refers to the phase that immediately follows inflation, but precedes the epoch of reheating. During this phase, the inflaton typically oscillates at the bottom of its potential and gradually transfers its energy to radiation. At the same time, the amplitude of the fields coupled to the inflaton may undergo parametric resonance and, as a consequence, explosive particle production can take place. A priori, these phenomena could lead to an amplification of the super-Hubble scale curvature perturbations which, in turn, would modify the standard inflationary predictions. However, remarkably, it has been shown that, although the Mukhanov-Sasaki variable does undergo narrow parametric instability during preheating, the amplitude of the corresponding super-Hubble curvature perturbations remain constant. Therefore, in single field models, metric preheating does not affect the power spectrum of the large scale perturbations. In this article, we investigate the corresponding effect on the scalar bispectrum. Using the Maldacena’s formalism, we analytically show that, for modes of cosmological interest, the contributions to the scalar bispectrum as the curvature perturbations evolve on super-Hubble scales during preheating is completely negligible. Specifically, we illustrate that, certain terms in the third order action governing the curvature perturbations which may naively be expected to contribute significantly are exactly canceled by other contributions to the bispectrum. We corroborate selected analytical results by numerical investigations. We conclude with a brief discussion of the results we have obtained.

A cosmological model of a flat Friedmann universe filled with a mixture of anti-Chaplygin gas and dustlike matter exhibits a future soft singularity, where the pressure of the anti-Chaplygin gas diverges (while its energy density is finite). Despite infinite tidal forces the geodesics pass through the singularity. Because of the dust component, the Hubble parameter has a nonzero value at the encounter with the singularity, therefore the dust implies further expansion. With continued expansion however, the energy density and the pressure of the anti-Chaplygin gas would become ill-defined hence from the point of view of the anti-Chaplygin gas only a contraction is allowed. Paradoxically, the universe in this cosmological model would have to expand and contract simultaneously. This obviously could not happen. We solve the paradox by redefining the anti-Chaplygin gas in a distributional sense. Then a contraction could follow the expansion phase at the singularity at the price of a jump in the Hubble parameter. Although such an abrupt change is not common in any cosmological evolution, we explicitly show that the set of Friedmann, Raychaudhuri and continuity equations are all obeyed both at the singularity and in its vicinity. We also prove that the Israel junction conditions are obeyed through the singular spatial hypersurface. In particular we enounce and prove a more general form of the Lanczos equation.

The indirect detection of dark matter requires that dark matter annihilation products be discriminated from conventional astrophysical backgrounds. Here, we re-analyze GeV-band gamma-ray observations of the prominent Milky Way dwarf satellite galaxy Segue 1, for which the expected astrophysical background is minimal. We explicitly account for the angular extent of the conservatively expected gamma-ray signal and keep the uncertainty in the dark-matter profile external to the likelihood analysis of the gamma-ray data.

We investigate the exclusive jet mass distribution in $e^{+}{e}^{-}$ events, defined with a veto on the out-of-jet radiation, at two-loop order. In particular, we calculate the two-loop soft function, which is required to describe this distribution in the region of small jet mass. When combined with other ingredients using the soft-collinear effective theory, this generates the complete singular distribution for jet thrust, the sum of the jet masses, at two-loop order. The result is in excellent agreement with full quantum chromodynamics. The integrated jet thrust distribution is found to depend in an intricate way on both the finite jet cone size, $R$, and the jet veto scale. The result clarifies the structure of the potentially large logarithms (both global and nonglobal) which arise in jet observables for the first time at this order. Somewhat surprisingly, we find that, in the small $R$ limit, there is a precise and simple correspondence between the nonglobal contribution to the integrated jet thrust distribution and the previously calculated nonglobal contribution to the integrated hemisphere soft function, including subleading terms. This suggests that the small $R$ limit may provide a useful expansion for studying other exclusive jet substructure observables.

We analyze the different parametrizations of a general four-zero texture mass matrix for quarks and leptons that are able to reproduce the Cabibbo-Kobayashi-Maskawa and Pontecorvo-Maki-Nakagawa-Sakata mixing matrices. This study is done through an ${\chi }^2$ analysis. In the quark sector, only four solutions are found to be compatible with the Cabibbo-Kobayashi-Maskawa mixing matrix. In the leptonic sector, using the last experimental results about the mixing angles in the neutrino sector, our ${\chi }^2$ analysis shows a preferred value for $m_{{\nu }_3}$ to be around 0.05 eV, independent of the parametrization of the four-zero texture mass matrices chosen for the charged leptons and neutrinos.

We study the behavior of a scalar field under a $z=3$ Lifshitz black hole background, in a way which is nonminimally coupled to the gravitational field. A general analytical solution is obtained along with two sets of quasinormal modes associated to different boundary conditions which can be imposed on the scalar field; a nonminimal coupling parameter appears explicitly on these solutions. Stability of quasinormal modes can be studied and ensured for both cases. Also, the reflection and absorption coefficients are calculated, as well as the absorption cross section which features an interesting behavior because of being attenuated by terms strongly dependant on the nonminimal coupling. By a suitable change of variables, a soliton solution can also be obtained, and the stability of the quasinormal modes are studied and ensured.

We study maximally helicity violating amplitude for the $2\to 5$ scattering in the multi-Regge kinematics. The Mandelstam cut correction to the Bern-Dixon-Smirnov amplitude is calculated in the leading logarithmic approximation and the corresponding remainder function is given to any loop order in a closed integral form. We show that the leading logarithmic approximation remainder function at two loops for $2\to 5$ amplitude can be written as a sum of two $2\to 4$ remainder functions due to recursive properties of the leading order impact factors. We also make some generalizations for the maximally helicity violating amplitudes with more external particles. The results of the present study are in agreement with the all leg two-loop symbol derived by Caron-Huot as shown in a parallel paper of one of the authors with collaborators.