Search

We present the first calculation of inclusive jet production in deep-inelastic scattering with approximate next-to-next-to-leading order (aNNLO) contributions, obtained from a unified threshold resummation formalism. The leading coefficients are computed analytically. We show that the aNNLO contributions reduce the theoretical prediction for jet production in deep-inelastic scattering, improve the description of the final HERA data in particular at high photon virtuality Q2 and increase the central fit value of the strong coupling constant [ABSTRACT FROM AUTHOR]

We present the first calculation of inclusive jet photoproduction with approximate next-to-next-toleading- order contributions, obtained from a unified threshold resummation formalism. The leading coefficients for direct photoproduction are computed analytically. Together with the coefficients pertinent to parton-parton scattering, they are shown to agree with those appearing in our full next-to-leading-order calculations. For hadron-hadron scattering, numerical agreement is found with a previous calculation of jet production at the Tevatron. We show that the direct and resolved approximate next-to-next-to-leading-order contributions considerably improve the description of final ZEUS data on jet photoproduction and that the error on the determination of the strong coupling constant is significantly reduced. [ABSTRACT FROM AUTHOR]

A singlet fermion which interacts only with a new singlet scalar provides a viable and minimal scenario that can explain the dark matter. The singlet fermion is the dark matter particle whereas the new scalar mixes with the Higgs boson providing a link between the dark matter sector and the standard model. In this paper, we present an updated analysis of this model focused on its detection prospects. Both the parity-conserving case and the most general case are considered. First, the full parameter space of the model is analyzed, and the regions compatible with the dark matter constraint are obtained and characterized. Then, the implications of current and future direct detection experiments are taken into account. Specifically, we determine the regions of the multidimensional parameter space that are currently excluded and those that are going to be probed by next generation experiments. Finally, indirect detection prospects are discussed and the expected signal at neutrino telescopes is calculated. [ABSTRACT FROM AUTHOR]

The parton densities of the proton are of fundamental importance not only for our description of hadronic and nuclear structure, but also for reliable predictions for new heavy-particle searches at colliders. At the large partonic momentum fractions required for the production of these particles, the parton distribution functions--in particular, that of the gluon--are unfortunately still badly constrained. In this paper, we investigate the possibility to improve on their determination with new data coming from electroweak vector boson production at large transverse momenta at the LHC with center-of-mass energies of 7, 8, or 14 TeV. We demonstrate that this process is dominated by quark-gluon scattering, that theoretical predictions can be reliably made on the basis of next-to-leading order perturbation theory and its resummation, and that these data should thus be used in global fits. We also point out that the nonperturbati ve parameters determined from Tevatron Run 1 Z-boson data at low pT describe very well the new LHC data at √s = 7 TeV. [ABSTRACT FROM AUTHOR]

The inert Higgs model is a minimal extension of the Standard Model that features a viable dark matter candidate, the so-called inert Higgs (H0). In this paper, we compute and analyze the dominant electroweak corrections to the direct detection cross section of dark matter within this model. These corrections arise from one-loop diagrams mediated by gauge bosons that, contrary to the tree-level result, do not depend on the unknown scalar coupling λ. We study in detail these contributions and show that they can modify in a significant way the prediction of the spin-independent direct detection cross section. In both viable regimes of the model, MH0

General SU(2) ✕ SU(2) ✕ U(l) model s represent a well-motivated intermediate step towards the unification of the standard model gauge groups. Based on a recent global analysis of low-energy and LEP constraints of these models, we perform numerical scans of their various signals at the LHC. We show that total cross sections for lepton and third-generation quark pairs, while experimentally easily accessible, provide individually only partial information about the model realized in nature. In contrast, correlations of these cross sections in the neutral and charged current channels may well lead to a unique identification. [ABSTRACT FROM AUTHOR]

We discuss the possibility of new sources of flavor violation in the squark sector of supersymmetric models in the context of the dark matter relic density. We show that the corresponding nonminimal flavor violation terms in the squark mass matrices can have an important impact on the thermally averaged (co) annihilation cross section of the neutralino, and in consequence can modify its predicted relic density. We discuss in detail the relevant effects and present a numerical study of neutralino annihilation and coannihilation in this context. We also comment on the LHC phenomenology of the corresponding scenarios. [ABSTRACT FROM AUTHOR]

Using next-to-leading order perturbative QCD, we calculate the diffractive contribution to inclusive dijet photoproduction in Pb-Pb ultraperipheral collisions (UPCs) at the LHC and find that it does not exceed 5-10% in small-xA bins in the ATLAS kinematics at √sNN=5.02 TeV. Its smallness is a result of the restricted kinematics (pT1>20 GeV and xA>0.001), the large nuclear suppression of nuclear diffractive parton distribution functions predicted in the leading twist model of nuclear shadowing, and additional suppression due to QCD factorization breaking in diffraction. At the same time, using looser pT cuts, e.g., pT1>10 GeV and pTi≠1>5-7 GeV, we find that (dσdiff/dxA)/(dσinc/dxA) can reach 10-20% at x≈5×10-4. Also, applying our framework to proton-proton UPCs at √sNN=13 TeV, we find that the ratio of the diffractive and inclusive cross sections of dijet photoproduction (dσdiff/dxp)/(dσinc/dxp) is as large as 10-15% for xp~5×10-4. An account of the contribution of Pomeron-Pomeron scattering, which is not included in our analysis, should make this ratio somewhat larger. [ABSTRACT FROM AUTHOR]

Using an artificial neural network, we explore the parameter space of supergravity grand unified models consistent with the combined Fermilab E989 and Brookhaven E821 data on (g-2)μ. Within an extended mSUGRA model with nonuniversal gaugino masses, the analysis indicates that the region favored by the data is the one generated by gluino-driven radiative breaking of the electroweak symmetry (˜gSUGRA). This region naturally leads to a split sparticle spectrum with light sleptons and weakinos but heavy squarks, with the stau and the chargino as the lightest charged particles. We show that if the entire deviation from the Standard Model (g-2)μ arises from supersymmetry, then supersymmetry is discoverable at HL-LHC and HE-LHC via production and decay of sleptons and sneutrinos within the optimal integrated luminosity of HL-LHC and with a smaller integrated luminosity at HE-LHC. The effect of CP phases on the muon anomaly is investigated, and the parameter space of CP phases excluded by the Fermilab constraint is exhibited. [ABSTRACT FROM AUTHOR]

We present a calculation of Higgsino and gaugino pair production at the LHC at next-to-next-to-leading logarithmic (NNLL) accuracy, matched to approximate next-to-next-to-leading order (aNNLO) QCD corrections. We briefly review the formalism for the resummation of large threshold logarithms and highlight the analytical results required at aNNLO+NNLO accuracy. Our numerical results are found to depend on the mass and nature of the produced charginos and neutralinos. The differential and total cross sections for light Higgsinos, which like sleptons are produced mostly at small x and in the s-channel, are found to be again moderately increased with respect to our previous results. The differential and total cross sections for gauginos are, however, not increased any more due to the fact that gauginos, like squarks, are now constrained by ATLAS and CMS to be heavier than about 1 TeV, so that also t- and u-channels play an important role. The valence quarks probed at large x then also induce substantially different cross sections for positively and negatively charged gauginos. The Higgsino and gaugino cross sections are both further stabilized at aNNLO+NNLL with respect to the variation of renormalization and factorization scales. We also now take mixing in the squark sector into account and study the dependence of the total cross sections on the squark and gluino masses as well as the trilinear coupling controlling the mixing in particular in the sbottom sector. [ABSTRACT FROM AUTHOR]

With the KATRIN experiment, the determination of the absolute neutrino mass scale down to cosmologically favored values has come into reach. We show that this measurement provides the missing link between the Standard Model and the dark sector in scotogenic models, where the suppression of the neutrino masses is economically explained by their only indirect coupling to the Higgs field. We determine the linear relation between the electron neutrino mass and the scalar coupling λ5 associated with the dark neutral scalar mass splitting to be λ5=3.1×10-9mνe/eV. This relation then induces correlations among the dark matter (DM) and new scalar masses and their Yukawa couplings. Together, KATRIN and future lepton flavor violation experiments can then probe the fermion DM parameter space, irrespective of the neutrino mass hierarchy and CP phase. [ABSTRACT FROM AUTHOR]

In minimal anomaly-mediated supersymmetry-breaking models, tachyonic sleptons are avoided by introducing a common scalar mass similar to the one introduced in minimal supergravity. This may lead to nonminimal flavor-violating interactions, e.g., in the squark sector. In this paper, we analyze the viable anomaly-mediated supersymmetry-breaking parameter space in the light of the latest limits on low-energy observables and LHC searches, complete our analytical calculations of flavor-violating supersymmetric particle production at hadron colliders with those related to gluino production, and study the phenome-nological consequences of nonminimal flavor violation in anomaly-mediated supersymmetry-breaking scenarios at the LHC. Related cosmological aspects are also briefly discussed. [ABSTRACT FROM AUTHOR]

We present a new calculation of next-to-leading order QCD corrections to electroweak top-quark pair hadroproduction in extensions of the Standard Model (SM) with extra heavy neutral and charged spin-1 resonances which considerably extends and improves an earlier calculation performed by some of us. In particular, we allow for flavor-non-diagonal Z' couplings and take into account nonresonant production in the SM and beyond including the contributions with t-channel W and W' bosons. As a result, models with a more complicated flavor structure which have been proposed to explain the flavor anomalies in B decays can now be accommodated in our code. Moreover, the new t-channel contributions lead to improved cross sections predictions at higher energies beyond the LHC reach. All amplitudes are generated using the recola2 package. As in our previous work, we include next-to-leading order QCD corrections and consistently match to parton showers with the POWHEG method fully taking into account the interference effects between the SM and new physics amplitudes. We consider the sequential Standard Model, the topcolor model, as well as the third family hypercharge model featuring non-flavor-diagonal Z' couplings and present numerical results for t̄t cross sections at hadron colliders with a center-of-mass energy up to 100 TeV. [ABSTRACT FROM AUTHOR]

Dark matter (DM) scattering and its subsequent capture in the Sun can boost the local relic density, leading to an enhanced neutrino flux from DM annihilations that is, in principle, detectable at neutrino telescopes. We calculate the event rates expected for a radiative seesaw model containing both scalar triplet and singlet-doublet fermion DM candidates. In the case of scalar DM, the absence of a spin dependent scattering on nuclei results in a low capture rate in the Sun, which is reflected in an event rate of less than one per year in the current IceCube configuration with 86 strings. For singlet-doublet fermion DM, there is a spin dependent scattering process next to the spin independent one, which significantly boosts the event rate and thus makes indirect detection competitive with respect to the direct detection limits imposed by pico-60. Because of a correlation between both scattering processes, the limits on the spin independent cross section set by xenon1t exclude also parts of the parameter space that can be probed at IceCube. Previously obtained limits by antares, IceCube, and super-kamiokande from the Sun and the Galactic Center are shown to be much weaker. [ABSTRACT FROM AUTHOR]