Search

We calculate the complete soft-gluon corrections for the production of colorless final states through N3LO in single-particle-inclusive kinematics. We present explicit analytical results and use them to study higher-order QCD corrections for the production of a heavy charged Higgs pair (H+H−) via quark-antiquark annihilation in the Two-Higgs-Doublet Model at LHC energies. We calculate the NNLO soft-gluon and virtual QCD corrections as well as the N3LO soft-gluon corrections to the total cross section and the charged-Higgs rapidity distribution. This is the first calculation of complete N3LO soft-gluon corrections for a process in single-particle-inclusive kinematics, and the results can be applied to other processes with colorless final states. [ABSTRACT FROM AUTHOR]

We study higher-order QCD corrections for the production of a top–antitop quark pair ( t t ¯ production) at the Large Hadron Collider in the Standard Model Effective Field Theory. We consider effects of new physics parametrized by the top-quark chromomagnetic dipole operator. We calculate new physics contributions to the total cross section at approximate NNLO, with second-order soft-gluon corrections added to the complete NLO result, including uncertainties from scale dependence and from parton distributions. We also calculate new physics contributions at approximate NNLO for differential distributions in top-quark transverse momentum. [ABSTRACT FROM AUTHOR]

The calculation of P-wave Sommerfeld enhancement in processes with unstable particles in the final state is known to be divergent. In a complete description, where resonant (on-shell unstable particles) and non-resonant contributions are included, it has been shown that results are finite. For most beyond the Standard Model applications, these complete calculations are not readily available. In this work, we are interested in the near-threshold region and we consider only the resonant contribution. In this case, we provide a simplified prescription to compute the P-wave Sommerfeld enhancement in the narrow-width approximation of the unstable particle that directly eliminates divergences. We show that we can define a finite resonant contribution without the inclusion of the non-resonant processes in a way similar to the usual S-wave Sommerfeld enhancement. [ABSTRACT FROM AUTHOR]

Itraconazole (ITZ) is an important drug in the treatment of superficial and deep mycoses in dogs. Its primary metabolite is hydroxy‐itraconazole, which has antifungal activity similar to the parent compound. The purpose of this study was to identify the cytochrome P450 enzyme (CYP) isoform(s) responsible for ITZ hydroxylation in canine liver. Reaction kinetics for ITZ hydroxylation were determined in a panel of canine recombinant CYPs and dog liver microsomes (DLMs). Findings were confirmed using CYP isoform‐specific inhibitors in rCYPs and DLMs. In rCYP experiments, CYP2D15 and CYP3A12 had highest activity for ITZ hydroxylation. In inhibitor experiments, quinidine and erythromycin inhibited ITZ hydroxylation in CYP2D15 and CYP3A12, respectively, in an isoform‐specific manner. In DLMs, quinidine and erythromycin combined inhibited ITZ hydroxylation more than erythromycin alone but not quinidine alone. However, this may be related to inhibitor potency rather than the contribution of the individual CYP isoforms to the reaction. These findings support a role for CYP2D15 and CYP3A12 in ITZ biotransformation in canine liver. [ABSTRACT FROM AUTHOR]

In theories of Partial Compositeness the top quark is a mixture of a composite and an elementary state, and as a consequence its interactions with gauge bosons are expected to deviate from those of a point-like object. At sufficiently large energies, such deviations cannot be parametrized by the leading effective field theory operators and form factors (i.e. energy dependent interactions) must be introduced. In this work, we argue that such effects might appear at relatively low energies with interesting phenomenological consequences. In analogy to the proton electromagnetic interactions, we devise a simplified phenomenological model that parametrizes the top-quark interactions with gluons in terms of two form factors. We study the implications of these interactions in top-quark and heavy top-partner pair production at a hadron collider. [ABSTRACT FROM AUTHOR]

We study effects of beyond the Standard Model physics coupling third generation quarks to leptons of the first two generations. We parametrize these effects by dimension-six effective operators, and we also consider related simplified UV completions: scalar leptoquark and Wt models. We derive new constraints on these scenarios by using recent ATLAS measurements of differential cross sections of single top production in association with a W boson, and also show how these limits will evolve with future data. We also describe how the limits can be significantly improved by using ratios of differential distributions with different flavours of leptons. [ABSTRACT FROM AUTHOR]

Based on a previous work on scenarios where the Standard Model and dark matter particles share a common asymmetry through effective operators at early time in the Universe and later on decouple from each other (not care), in this work, we study in detail the collider phenomenology of these scenarios. In particular, we use the experimental results from the Large Hadron Collider (LHC) to constrain the viable parameter space. Besides effective operators, we also constrain the parameter space of some representative ultraviolet complete models with experimental results from both the LHC and the Large Electron-Positron Collider. Specifically, we use measurements related to jets + missing transverse energy (MET), di-jets and photon + MET. In the case of ultraviolet models, depending on the assumptions on the couplings and masses of mediators, the derived constraints can become more or less stringent. We consider also the situation where one of the mediators has mass below 100 GeV, in this case we use the ultraviolet model to construct a new effective operator responsible for the sharing of the asymmetry and study its phenomenology. [ABSTRACT FROM AUTHOR]

We review and update current limits on possible anomalous couplings of the top quark to gauge bosons. We consider data from top quark decay (as encoded in the W-boson helicity fractions) and single-top production (in the t-, s- and W t-channels). We find improved limits with respect to previous results (in most cases of almost one order of magnitude) and extend the analysis to include four-quark operators. We find that new electroweak physics is constrained to live above an energy scale between 430 GeV and 3.2 TeV (depending on the form of its contribution). For comparison, strongly interacting new physics is bounded by scales higher than 1.3 or 1.5 TeV (again depending on its contribution). [ABSTRACT FROM AUTHOR]

We study the collider phenomenology of a simplified model containing a right-handed W in which the WR couples predominantly to the third generation in the quark sector. The model also includes a light Majorana neutrino, with M1 ∼ O 100 GeV, giving rise to lepton-number-violating signatures that are visible at the LHC. Taking into account all the searches from the LHC and Tevatron, we find that this WR can still be as light as MR ∼ 300 GeV. We show that this type of new physics, and others like it, can be detected at the LHC using final states with three same-sign same-flavour leptons. [ABSTRACT FROM AUTHOR]

The lightness of the Standard Model (SM) neutrinos could be understood if their masses were to be generated by new physics at a high scale, through the so-called seesaw mechanism involving heavy fermion singlets. We consider a novel scenario where the new physics violates baryon minus lepton number by only a small amount resulting in both heavy fermion singlets and the SM neutrinos to split into pairs of quasi-Dirac states. Above the weak scale, the cosmic matter-antimatter asymmetry can be generated through resonant leptogenesis from decay of heavy singlets. Nontrivially, the CP violation for leptogenesis is bounded from above by the light neutrino mass splitting which can be probed in neutrino oscillation experiments. [ABSTRACT FROM AUTHOR]

We study the effects of new physics in double Higgs production at future e+e− colliders. In the Standard Model the chiral limit (me = 0) plays an important role for this process, being responsible for the smallness of the tree-level diagrams with respect to the 1-loop contributions. In our work, we consider the possibility of an enhancement due to the contribution of Standard Model dimension-six effective operators. We show that there are only two relevant operators for this process that are not yet (strongly) constrained by other data. We perform a sensitivity study on the operator coefficients for several benchmark values of energy and integrated luminosity related to the proposed linear colliders such as CLIC, ILC and FCC-ee and we derive expected 95% CL limits for each benchmark scenario. [ABSTRACT FROM AUTHOR]

The "exact" or "functional" renormalization group equation describes the renormalization group flow of the effective average action Γk . The ordinary effective action Γ0 can be obtained by integrating the flow equation from an ultraviolet scale k = Λ down to k = 0. We give several examples of such calculations at one-loop, both in renormalizable and in effective field theories. We reproduce the four-point scattering amplitude in the case of a real scalar field theory with quartic potential and in the case of the pion chiral Lagrangian. In the case of gauge theories, we reproduce the vacuum polarization of QED and of Yang-Mills theory. We also compute the two-point functions for scalars and gravitons in the effective field theory of scalar fields minimally coupled to gravity [ABSTRACT FROM AUTHOR]

Abstract: We consider a model in which Goldstone bosons, described by a chiral nonlinear σ model, are coupled to an N-plet of colored fermions by means of a Yukawa interaction. We study the one-loop renormalization group flow and show that the non-Gaussian UV fixed point, which is present in the purely bosonic model, is lost because of fermion loop effects unless N is sufficiently large. We then add four-fermion contact interactions to the Lagrangian and show that in this case there exist several non-Gaussian fixed points. The strength of the contact interactions, predicted by the requirement that the theory flows towards a fixed point in the UV, is compared to the current experimental bounds. This toy model could provide an important building block of an asymptotically safe model of the weak interactions. [Copyright &y& Elsevier]