Fri·Nov 4, 2016Friday·November 4, 2016

1. 01*

   Dark matter decay through gravity portals

   Oscar Catà🇩🇪 · Alejandro Ibarra🇩🇪 · Sebastian Ingenhütt🇩🇪

   Motivated by the fact that, so far, the whole body of evidence for dark matter is of gravitational origin, we study the decays of dark matter into Standard Model particles mediated by gravity portals, i.e., through nonminimal gravitational interactions of dark matter. We investigate the decays in several widely studied frameworks of scalar and fermionic dark matter where the dark matter is stabilized in flat spacetime via global symmetries. We find that the constraints on the scalar singlet dark matter candidate are remarkably strong and exclude large regions of the parameter space, suggesting that an additional stabilizing symmetry should be in place. In contrast, the scalar doublet and the fermionic singlet candidates are naturally protected against too fast decays by gauge and Lorentz symmetry, respectively. For a nonminimal coupling parameter $\xi \sim \mathcal{O}(1)$, decays through the gravity portal are consistent with observations if the dark matter mass is smaller than $\sim 10^5$ GeV, for the scalar doublet, and $\sim 10^6$ GeV, for the fermionic singlet.

   hep-phastro-ph.COPRD(2017)·26 citations
2. 02*

   LHC multijet events as a probe for anomalous dimension-six gluon interactions

   Frank Krauss🇬🇧 · Silvan Kuttimalai🇬🇧 · Tilman Plehn🇩🇪

   Higher-dimensional multi-gluon interactions affect essentially all effective Lagrangian analyses at the LHC. We show that, contrary to common lore, such operators are best constrained in multi-jet production. Our limit on the corresponding new physics scale in the multi-TeV range exceeds the typical reach of global dimension-6 Higgs and top analyses. This implies that the pure Yang-Mills operator can safely be neglected in almost all specific higher-dimensional analyses at Run II.

   hep-phPRD(2017)·73 citations
3. 03*

   Implications of a Stop Sector Signal at the LHC

   Aaron Pierce🇺🇸 · Bibhushan Shakya🇺🇸

   Naturalness arguments suggest that the stop sector is within reach of the Large Hadron Collider (LHC). We investigate how the observation of a third generation squark signal could predict masses and discovery modes of other supersymmetric particles, or potentially test the Higgs boson mass relation and the validity of the Minimal Supersymmetric Standard Model (MSSM) at the high luminosity LHC. We illustrate these ideas in three distinct scenarios: discovery of a light stop, a sbottom signal in multileptons, and a signal of the second (heavier) stop in boosted dibosons.

   hep-phhep-exJHEP(2018)·8 citations
4. 04*

   PeV Neutrino Events at IceCube from Single Top-Quark Production

   Vernon Barger🇺🇸 · Edward Basso🇺🇸 · Yu Gao🇺🇸 · Wai-Yee Keung🇺🇸

   Deep inelastic scattering of very high-energy neutrinos can potentially be enhanced by the production of a single top quark or charm quark via the interaction of a virtual $W$-boson exchange with a $b$-quark or $s$-quark parton in the nucleon. The single top contribution shows a sharp rise at neutrino energies above 0.5 PeV and gives a cross-section contribution of order 5 percent at 10 PeV, while single charm has a low energy threshold and contributes about 25 percent. Semi-leptonic decays of top and charm give di-muon events whose kinematic characteristics are shown. The angular separation of the di-muons from heavy quark production in the IceCube detector can reach up to one degree. Top quark production has a unique, but rare, three muon signal.

   hep-phastro-ph.HEPRD(2017)·17 citations
5. 05*

   Flavor from the double tetrahedral group without supersymmetry

   Christopher D. Carone🇺🇸 · Shikha Chaurasia🇺🇸 · Savannah Vasquez🇺🇸

   We consider a class of flavor models proposed by Aranda, Carone and Lebed, relaxing the assumption of supersymmetry and allowing the flavor scale to float anywhere between the weak and Planck scales. We perform global fits to the charged fermion masses and CKM angles, and consider the dependence of the results on the unknown mass scale of the flavor sector. We find that the typical Yukawa textures in these models provide a good description of the data over a wide range of flavor scales, with a preference for those that approach the lower bounds allowed by flavor-changing-neutral-current constraints. Nevertheless, the possibility that the flavor scale and Planck scale are identified remains viable. We present models that demonstrate how the assumed textures can arise most simply in a non-supersymmetric framework.

   hep-phPRD(2017)·12 citations
6. 06*

   Electroweak Splitting Functions and High Energy Showering

   Junmou Chen🇺🇸 · Tao Han🇺🇸 · Brock Tweedie🇺🇸

   We derive the electroweak (EW) collinear splitting functions for the Standard Model, including the massive fermions, gauge bosons and the Higgs boson. We first present the splitting functions in the limit of unbroken SU(2)xU(1) and discuss their general features in the collinear and soft-collinear regimes. We then systematically incorporate EW symmetry breaking (EWSB), which leads to the emergence of additional "ultra-collinear" splitting phenomena and naive violations of the Goldstone-boson Equivalence Theorem. We suggest a particularly convenient choice of non-covariant gauge (dubbed "Goldstone Equivalence Gauge") that disentangles the effects of Goldstone bosons and gauge fields in the presence of EWSB, and allows trivial book-keeping of leading power corrections in the VEV. We implement a comprehensive, practical EW showering scheme based on these splitting functions using a Sudakov evolution formalism. Novel features in the implementation include a complete accounting of ultra-collinear effects, matching between shower and decay, kinematic back-reaction corrections in multi-stage showers, and mixed-state evolution of neutral bosons (gamma/Z/h) using density-matrices. We employ the EW showering formalism to study a number of important physical processes at O(1-10 TeV) energies. They include (a) electroweak partons in the initial state as the basis for vector-boson-fusion; (b) the emergence of "weak jets" such as those initiated by transverse gauge bosons, with individual splitting probabilities as large as O(30%); (c) EW showers initiated by top quarks, including Higgs bosons in the final state; (d) the occurrence of O(1) interference effects within EW showers involving the neutral bosons; and (e) EW corrections to new physics processes, as illustrated by production of a heavy vector boson (W') and the subsequent showering of its decay products.

   hep-phhep-exJHEP(2017)·139 citations
7. 07*

   Why static bound-state calculations of tetraquarks should be met with scepticism

   George Rupp🇵🇹 · Eef van Beveren🇵🇹

   Recent experimental signals have led to a revival of tetraquarks, the hypothetical $q^2{\bar{q}}^2$ hadronic states proposed by Jaffe in 1976 to explain the light scalar mesons. Mesonic structures with exotic quantum numbers have indeed been observed recently, though a controversy persists whether these are true resonances and not merely kinematical threshold enhancements, or otherwise states not of a true $q^2{\bar{q}}^2$ nature. Moreover, puzzling non-exotic mesons are also often claimed to have a tetraquark configuration. However, the corresponding model calculations are practically always carried out in pure and static bound-state approaches, ignoring completely the coupling to asymptotic two-meson states and unitarity, especially the dynamical effects thereof. In this short paper we argue that such static predictions of real tetraquark masses are highly unreliable and provide little evidence of the very existence of such states.

   hep-phhep-exCPC(2017)·9 citations
8. 08*

   Quark and gluon form factors to four loop order in QCD: the $N_f^3$ contributions

   Andreas von Manteuffel🇩🇪 · Robert M. Schabinger🇮🇪

   We calculate the four-loop massless QCD corrections with three closed quark lines to quark and gluon form factors. We apply a novel integration by parts algorithm based on modular arithmetic and compute all relevant master integrals for arbitrary values of the space-time dimension. This is the first calculation of a gluon form factor at this perturbative order in QCD.

   hep-phhep-thPRD(2017)·79 citations
9. 09*

   The last refuge of mixed wino-Higgsino dark matter

   Martin Beneke🇩🇪 · Aoife Bharucha🇫🇷 · Andrzej Hryczuk🇳🇴 · Stefan Recksiegel🇩🇪 · Pedro Ruiz-Femenia🇩🇪

   We delineate the allowed parameter and mass range for a wino-like dark matter particle containing some Higgsino admixture in the MSSM by analysing the constraints from diffuse gamma-rays from the dwarf spheroidal galaxies, galactic cosmic rays, direct detection and cosmic microwave background anisotropies. A complete calculation of the Sommerfeld effect for the mixed-neutralino case is performed. We find that the combination of direct and indirect searches poses significant restrictions on the thermally produced wino-Higgsino dark matter with correct relic density. For $\mu >0$ nearly the entire parameter space considered is excluded, while for $\mu <0$ a substantial region is still allowed, provided conservative assumptions on astrophysical uncertainties are adopted.

   hep-phastro-ph.HEJHEP(2017)·51 citations
10. 10*

    Effects of $Z_b$ states and bottom meson loops on ${\rm Y}(4S)\to {\rm Y}(1S,2S){\pi }^{+}{\pi }^{-}$ transitions

    Yun-Hua Chen🇩🇪 · Martin Cleven🇪🇸 · Johanna T. Daub🇩🇪 · Feng-Kun Guo🇨🇳 · Christoph Hanhart🇩🇪 · Bastian Kubis🇩🇪 · Ulf-G. Meißner🇩🇪 · Bing-Song Zou🇨🇳

    We study the dipion transitions ${\rm Y}(4S)\to {\rm Y}(nS){\pi }^{+}{\pi }^{-}$ $(n=1,2)$. In particular, we consider the effects of the two intermediate bottomoniumlike exotic states $Z_b(10610)$ and $Z_b(10650)$ as well as bottom meson loops. The strong pion-pion final-state interactions, especially including channel coupling to $K\bar{K}$ in the $S$-wave, are taken into account model-independently by using dispersion theory. Based on a nonrelativistic effective field theory we find that the contribution from the bottom meson loops is comparable to those from the chiral contact terms and the $Z_b$-exchange terms. For the ${\rm Y}(4S)\to {\rm Y}(2S){\pi }^{+}{\pi }^{-}$ decay, the result shows that including the effects of the $Z_b$-exchange and the bottom meson loops can naturally reproduce the two-hump behavior of the $\pi \pi$ mass spectra. Future angular distribution data are decisive for the identification of different production mechanisms. For the ${\rm Y}(4S)\to {\rm Y}(1S){\pi }^{+}{\pi }^{-}$ decay, we show that there is a narrow dip around 1 GeV in the $\pi \pi$ invariant mass distribution, caused by the final-state interactions. The distribution is clearly different from that in similar transitions from lower ${\rm Y}$ states, and needs to be verified by future data with high statistics. Also we predict the decay width and the dikaon mass distribution of the ${\rm Y}(4S)\to {\rm Y}(1S)K^{+}{K}^{-}$ process.

    hep-phhep-exnucl-thPRD(2017)·55 citations
11. 11*

    The impact of intrinsic charm on the parton distribution functions

    Alireza Aleedaneshvar🇮🇷 · Muhammad Goharipour🇮🇷 · Saeedeh Rostami🇮🇷

    In this work, we present a new investigation about the impact of intrinsic charm (IC) on the physical observables, in particular, on the heavy structure function $F_2^c$. Since IC distribution is dominant at large Bjorken variable $x$, normally, it is expected that it can be explored only at large $x$. But, by studying the correlation of the charm density in the proton with $F_2^c$, we are going to show that the IC component can also be effective at low $x$. To investigate further, we perform three QCD global analyses of parton distribution functions (PDFs), by including the EMC $F_2^c$ data that are recognized as clear evidence for existence of the intrinsic charm in the proton, and also by considering the IC component. Although the fit of the EMC data is extremely poor due to the data points with lower $x$ values, i.e. $x<$0.05, but these analyses can give us new information about the impact of EMC data and IC contribution on the behaviour of PDFs.

    hep-phEPJA(2016)·6 citations
12. 12*

    One-loop pseudo-Goldstone masses in the minimal $SO(10)$ Higgs model

    Lukáš Gráf🇬🇧 · Michal Malinský🇨🇿 · Timon Mede🇭🇷 · Vasja Susič🇨🇭

    We calculate the prominent perturbative contributions shaping the one-loop scalar spectrum of the minimal non-supersymmetric renormalizable $SO(10)$ Higgs model whose unified gauge symmetry is spontaneously broken by an adjoint scalar. Focusing on its potentially realistic $45\oplus 126$ variant in which the rank is reduced by a VEV of the 5-index self-dual antisymmetric tensor, we provide a thorough analysis of the corresponding one-loop Coleman-Weinberg potential, paying particular attention to the masses of the potentially tachyonic pseudo-Goldstone bosons (PGBs) transforming as $(8,1,0)$ and $(1,3,0)$ under the Standard Model gauge group. The results confirm the assumed existence of extended regions in the parameter space supporting a locally stable SM-like quantum vacuum inaccessible at the tree-level. The effective potential (EP) tedium is compared to that encountered in the previously studied $45\oplus 16$ $SO(10)$ Higgs model where the polynomial corrections to the relevant pseudo-Goldstone masses turn out to be easily calculable within a very simplified purely diagrammatic approach.

    hep-phPRD(2017)·23 citations
13. 13*

    Transforming differential equations of multi-loop Feynman integrals into canonical form

    Christoph Meyer🇩🇪

    The method of differential equations has been proven to be a powerful tool for the computation of multi-loop Feynman integrals appearing in quantum field theory. It has been observed that in many instances a canonical basis can be chosen, which drastically simplifies the solution of the differential equation. In this paper, an algorithm is presented that computes the transformation to a canonical basis, starting from some basis that is, for instance, obtained by the usual integration-by-parts reduction techniques. The algorithm requires the existence of a rational transformation to a canonical basis, but is otherwise completely agnostic about the differential equation. In particular, it is applicable to problems involving multiple scales and allows for a rational dependence on the dimensional regulator. It is demonstrated that the algorithm is suitable for current multi-loop calculations by presenting its successful application to a number of non-trivial examples.

    hep-phhep-thJHEP(2017)·122 citations
14. 14*

    Probing Majorana Neutrino Textures at DUNE

    Kalpana Bora🇮🇳 · Debasish Borah🇮🇳 · Debajyoti Dutta🇮🇳

    We study the possibility of probing different texture zero neutrino mass matrices at long baseline neutrino experiment DUNE. Assuming a diagonal charged lepton basis and Majorana nature of light neutrinos, we first classify the possible light neutrino mass matrices with one and two texture zeros and then numerically evaluate the parameter space in terms of atmospheric mixing angle ${\theta }_{23}$ and Dirac CP phase ${\delta }_{\text{CP}}$ which satisfies the texture zero conditions. We then feed these parameter values into the numerical analysis in order to study the sensitivity of DUNE experiment to them. We find that the DUNE will be able to exclude some of these texture zero mass matrices which restrict the $({\theta }_{23}-{\delta }_{\text{CP}})$ to a very specific range of values.

    hep-phPRD(2017)·26 citations
15. 15*

    Heavy flavour corrections to polarised and unpolarised deep-inelastic scattering at 3-loop order

    Jakob Ablinger🇦🇹 · Arnd Behring🇩🇪 · Johannes Blümlein🇩🇪 · Abilio De Freitas🇩🇪 · Alexander Hasselhuhn🇩🇪 · Andreas von Manteuffel🇩🇪 · Mark Round🇦🇹 · Carsten Schneider🇦🇹 · Fabian Wißbrock🇫🇷

    We report on progress in the calculation of 3-loop corrections to the deep-inelastic structure functions from massive quarks in the asymptotic region of large momentum transfer $Q^2$. Recently completed results allow us to obtain the $O(a_s^3)$ contributions to several heavy flavour Wilson coefficients which enter both polarised and unpolarised structure functions for lepton-nucleon scattering. In particular, we obtain the non-singlet contributions to the unpolarised structure functions $F_2(x,Q^2)$ and $x{F}_3(x,Q^2)$ and the polarised structure function $g_1(x,Q^2)$. From these results we also obtain the heavy flavour contributions to the Gross-Llewellyn-Smith and the Bjorken sum rules.

    hep-phPoS(2016)·8 citations
16. 16*

    Higgs EFT for 2HDM and beyond

    Hermès Bélusca-Maïto🇫🇷 · Adam Falkowski🇫🇷 · Duarte Fontes🇵🇹 · Jorge C. Romão🇵🇹 · João P. Silva🇵🇹

    We discuss the validity of the Standard Model Effective Field Theory (SM EFT) as the low-energy effective theory for the two-Higgs-doublet Model (2HDM). Using the up-to-date Higgs signal strength measurements at the LHC, one can obtain a likelihood function for the Wilson coefficients of dimension-6 operators in the EFT Lagrangian. Given the matching between the 2HDM and the EFT, the constraints on the Wilson coefficients can be translated into constraints on the parameters of the 2HDM Lagrangian. We discuss under which conditions such a procedure correctly reproduces the true limits on the 2HDM. Finally, we employ the SM EFT to identify the pattern of the Higgs boson couplings that are needed to improve the fit to the current Higgs data. To this end, one needs, simultaneously, to increase the top Yukawa coupling, decrease the bottom Yukawa coupling, and induce a new contact interaction of the Higgs boson with gluons. We comment on how these modifications can be realized in the 2HDM extended by new colored particles.

    hep-phEPJC(2017)·61 citations
17. 17*

    Constraints on atmospheric charmed-meson production from IceCube

    Tomasz Palczewski (1,2,3) (for the IceCube Collaboration) ((1) University of California, Berkeley, USA, (2) Lawrence Berkeley National Laboratory, Berkeley, USA, (3) http://icecube.wisc.edu)🇺🇸

    At very-high energies (100 TeV - 1 PeV), the small value of Bjorken-x ($\le 10^{-3}-10^{-7}$) at which the parton distribution functions are evaluated makes the calculation of charm quark production very difficult. The charm quark has mass ($\sim$1.5$\pm$0.2 GeV) significantly above the $\Lambda$${}_{QCD}$ scale ($\sim$200 MeV), and therefore its production is perturbatively calculable. However, the uncertainty in the data and the calculations cannot exclude some smaller non-perturbative contribution. To evaluate the prompt neutrino flux, one needs to know the charm production cross-section in pN -> c$\bar{c}$ X, and hadronization of charm particles. This contribution briefly discusses computation of prompt neutrino flux and presents the strongest limit on prompt neutrino flux from IceCube.

    ↳ astro-ph.HEhep-phEPJ Web Conf.(2016)·1 citation
18. 18*

    Ultra-Light Axion Dark Matter and its impacts on dark halo structure in $N$-body simulation

    Jiajun Zhang🇨🇳 · Yue-Lin Sming Tsai🇹🇼 · Jui-Lin Kuo🇹🇼 · Kingman Cheung🇹🇼 · Ming-Chung Chu🇨🇳

    The Ultra-Light Axion (ULA) is a dark matter candidate with mass $\mathcal{O}(10^{-22})$eV and de Broglie wavelength of order kpc. Such an axion, also called the Fuzzy Dark Matter (FDM), thermalizes via the gravitational force and forms a Bose-Einstein condensate. Recent studies suggested that the quantum pressure from the FDM can significantly affect the structure formation in small scales, thus alleviating the so-called "small-scale crisis". In this paper, we develop a new technique to discretize the quantum pressure and illustrate the interactions among FDM particles in the $N$-body simulation, which accurately simulates the formation of the dark-matter halo and its inner structure in the region outside the softening length. In a self-gravitationally-bound virialized halo, we find a constant density, solitonic core, which is consistent with the theoretical prediction. The existence of the solitonic core reveals the non-linear effect of quantum pressure and impacts the structure formation in the FDM model.

    ↳ astro-ph.COastro-ph.GAhep-phApJ(2018)·68 citations
19. 19*

    Testing the hadro-quarkonium model on the lattice

    Francesco Knechtli🇩🇪 · Maurizio Alberti🇩🇪 · Gunnar S. Bali🇩🇪 · Sara Collins🇩🇪 · Graham Moir🇬🇧 · Wolfgang Söldner🇩🇪

    Recently the LHCb experiment found evidence for the existence of two exotic resonances consisting of $c\bar{c}uud$ quarks. Among the possible interpretations is the hadro-charmonium model, in which charmonium is bound "within" a light hadron. We test this idea on CLS $N_f$=2+1 lattices using the static formulation for the heavy quarks. We find that the static potential is modified by the presence of a hadron such that it becomes more attractive. The effect is of the order of a few MeV.

    ↳ hep-lathep-phPoS(2016)·0 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.