Mon·Feb 12, 2018Monday·February 12, 2018

1. 01*

   Robust Constraints and Novel Gamma-Ray Signatures of Dark Matter That Interacts Strongly With Nucleons

   Dan Hooper🇺🇸 · Samuel D. McDermott🇺🇸

   Due to shielding, direct detection experiments are in some cases insensitive to dark matter candidates with very large scattering cross sections with nucleons. In this paper, we revisit this class of models, and derive a simple analytic criterion for conservative but robust direct detection limits. While large spin-independent cross sections seem to be ruled out, we identify potentially viable parameter space for dark matter with a spin-dependent cross section with nucleons in the range of $10^{-27}{\mathrm{cm}}^2<{\sigma }_{\mathrm{DM}-p}<10^{-24}{\mathrm{cm}}^2$. With these parameters, cosmic-ray scattering with dark matter in the extended halo of the Milky Way could generate a novel and distinctive gamma-ray signal at high galactic latitudes. Such a signal could be observable by Fermi or future space-based gamma-ray telescopes.

   hep-phastro-ph.COastro-ph.GAastro-ph.HEPRD(2018)·85 citations
2. 02*

   Return of the grand unified theory baryogenesis: Source of helical hypermagnetic fields for the baryon asymmetry of the universe

   Kohei Kamada🇰🇷

   It has been considered that baryogenesis models without a generation of $B$-$L$ asymmetry such as the GUT baryogenesis do not work since the asymmetry is washed out by the electroweak sphalerons. Here, we point out that helical hypermagnetic fields can be generated through the chiral magnetic effect with a chiral asymmetry generated in such baryogenesis models. The helical hypermagnetic fields then produce baryon asymmetry mainly at the electroweak symmetry breaking, which remains until today. Therefore, the baryogenesis models without $B$-$L$ asymmetry can still be the origin of the present baryon asymmetry. In particular, if it can produce chiral asymmetry mainly carried by right-handed electrons of order of $10^{-3}$ in terms of the chemical potential to temperature ratio, the resultant present-day baryon asymmetry can be consistent with our Universe, although simple realizations of the GUT baryogenesis are hard to satisfy the condition. We also argue the way to overcome the difficulty in the GUT baryogenesis. The intergalactic magnetic fields with $B_0\sim 10^{-16\sim 17}$ G and ${\lambda }_0\sim 10^{-2\sim 3}$ pc are the smoking gun of the baryogenesis scenario as discussed before.

   hep-phastro-ph.COhep-thPRD(2018)·43 citations
3. 03*

   Doubly-charged scalar in rare decays of $B_c$ meson

   Tianhong Wang🇨🇳 · Yue Jiang🇨🇳 · Zhi-Hui Wang🇨🇳 · Guo-Li Wang🇨🇳

   In this paper, we study the lepton number violation processes of $B_c$ meson induced by possible doubly-charged scalars. Both the three-body decay channels and the four-body decay channels are considered. For the former, $Br\times {\left(\frac{s_{\Delta }{h}_{ij}}{M_{\Delta }^2}\right)}^{-2}$ is of the order of $10^{-7}\sim 10^{-9}$, and for the later channels, $Br\times {\left(\frac{s_{\Delta }{h}_{ij}}{M_{\Delta }^2}\right)}^{-2}$ is of the order of $10^{-12}\sim 10^{-20}$, where $s_{\Delta }$, $h_{ij}$, $M_{\Delta }$ are the constants related to the doubly-charged boson.

   hep-phPRD(2018)·6 citations
4. 04*

   Statistical approach of pion parton distributions from Drell-Yan process

   Claude Bourrely🇫🇷 · Jacques Soffer🇺🇸

   The quantum statistical approach proposed more than one decade ago was used to determine the parton distributions for the proton by considering a large set of accurate Deep Inelastic Scattering experimental results. We propose to extend this work to extract the parton distributions for the pion by using data on lepton pair production from various experiments. This global next-to-leading order QCD analysis leads to a good description of several Drell-Yan ${\pi }^{-}W$ data. The resulting parton distributions are compared with earlier determinations. We will also discuss the difference between nucleon and pion structure in the same approach.

   hep-phnucl-exNPA(2019)·18 citations
5. 05*

   Surrogate Models for Direct Dark Matter Detection

   D.G. Cerdeno🇬🇧 · A. Cheek🇬🇧 · E. Reid🇬🇧 · H. Schulz🇺🇸

   In this work we introduce RAPIDD, a surrogate model that speeds up the computation of the expected spectrum of dark matter particles in direct detection experiments. RAPIDD replaces the exact calculation of the dark matter differential rate (which in general involves up to three nested integrals) with a much faster parametrization in terms of ordinary polynomials of the dark matter mass and couplings, obtained in an initial training phase. In this article, we validate our surrogate model on the multi-dimensional parameter space resulting from the effective field theory description of dark matter interactions with nuclei, including also astrophysical uncertainties in the description of the dark matter halo. As a concrete example, we use this tool to study the complementarity of different targets to discriminate simplified dark matter models. We demonstrate that RAPIDD is fast and accurate, and particularly well-suited to explore a multi-dimensional parameter space, such as the one in effective field theory approach, and scans with a large number of evaluations.

   hep-phastro-ph.COJCAP(2018)·21 citations
6. 06*

   On the completeness and orthonormality of the Volkov states and the Volkov propagator in configuration space

   A. Di Piazza🇩🇪

   Volkov states and Volkov propagator are the basic analytical tools to investigate QED processes occurring in the presence of an intense plane-wave electromagnetic field. In the present paper we provide alternative and relatively simple proofs of the completeness and of the orthonormality at a fixed time of the Volkov states. Concerning the completeness, we exploit some known properties of the Green's function of the Dirac operator in a plane wave, whereas the orthonormality of the Volkov states is proved, relying only on a geometric argument based on the Gauss theorem in four dimensions. In relation with the completeness of the Volkov states, we also study some analytical properties of the Green's function of the Dirac operator in a plane wave, which we explicitly prove to coincide with the Volkov propagator in configuration space. In particular, a closed-form expression in terms of modified Bessel functions and Hankel functions is derived by means of the operator technique in a plane wave and different asymptotic forms are determined. Finally, the transformation properties of the Volkov propagator under general gauge transformations and a general gauge-invariant expression of the so-called dressed mass in configuration space are presented.

   hep-phPRD(2018)·29 citations
7. 07*

   Perturbative corrections to technicolor

   A. C. Aguilar🇧🇷 · A. Doff🇧🇷 · A. A. Natale🇧🇷

   The full solution of technicolor (TC) Schwinger-Dyson equations should include radiative corrections induced by extended technicolor (ETC) (or other) interactions. We verify that when TC is embedded into a larger theory including also QCD, these radiative corrections couple the different strongly interacting Schwinger-Dyson equations, providing a tiny mass to technifermions and changing the ultraviolet behavior of the gap equation solution. We argue about the origin of the different quark masses without appealing for different ETC boson masses, in one scenario where most of the new physics will appear in interactions with the third fermion generation and with a TC scalar boson possibly lighter than the TC characteristic scale (${\Lambda }_{\mathtt{TC}}$)

   hep-phhep-lathep-thPRD(2018)·11 citations
8. 08*

   Electroweak interaction beyond the Standard Model and Dark Matter in the Tangent Bundle Quantum Field Theory

   Joachim Herrmann🇩🇪

   A generalized theory of electroweak interaction is developed based on the underlying geometrical structure of the tangent bundle with symmetries arising from transformations of tangent vectors along the fiber axis at a fixed space-time point, leaving the scalar product invariant. Transformations with this property are given by the $SO(3,1)$ group with the little groups $SU(2),E^c(2)$ and $SU(1,1)$ where the group $E^c(2)$ is the central extended group of the Euclidian group $E(2).$ Electroweak interaction beyond the standard model (SM) is described by the transformation group $SU(2)\otimes E^c(2)$ without a priori introduction of a phenomenologically determined gauge group. The Laplacian on this group yields the known internal quantum numbers of isospin and hypercharge, but in addition the extra $E^c$-charge $\varkappa$ and the family quantum number $n$ which explains the existence of families in the SM. The connection coefficients deliver the SM gauge potentials but also hypothetical gauge bosons and other hypothetical particles as well as candidate Dark Matter particles are predicted. It is shown that the interpretation of the $SO(3,1)$ connection coefficients as elctroweak gauge potentials is compatible with teleparallel gauge gravity theory based on the translational group.

   hep-phhep-thEPJC(2019)·2 citations
9. 09*

   Production of $W^{+}{W}^{-}$ pairs via ${\gamma }^{\ast }{\gamma }^{\ast }\to W^{+}{W}^{-}$ subprocess with photon transverse momenta

   Marta Luszczak🇵🇱 · Wolfgang Schäfer🇵🇱 · Antoni Szczurek🇵🇱

   We discuss production of $W^{+}{W}^{-}$ pairs in proton-proton collisions induced by two-photon fusion including, for a first time, transverse momenta of incoming photons. The unintegrated inelastic fluxes (related to proton dissociation) of photons are calculated based on modern parametrizations of deep inelastic structure functions in a broad range of their arguments ($x$ and $Q^2$). In our approach we can get separate contributions of different $W$ helicities states. Several one- and two-dimensional differential distributions are shown and discussed. The present results are compared to the results of previous calculations within collinear factorization approach. Similar results are found except of some observables such as e.g. transverse momentum of the pair of $W^{+}$ and $W^{-}$. We find large contributions to the cross section from the region of large photon virtualities. We show decomposition of the total cross section as well as invariant mass distribution into polarisation states of both W bosons. The role of the longitudinal $F_L$ structure function is quantified. Its inclusion leads to a 4-5 % decrease of the cross section, almost independent of $M_{WW}$.

   hep-phJHEP(2018)·21 citations
10. 10*

    Alignment Limit in 2HDM: Robustness put to test

    Siddhartha Karmakar🇮🇳 · Subhendu Rakshit🇮🇳

    In a two-Higgs-doublet model (2HDM), at the vicinity of the alignment limit, the extra contributions to the couplings of the SM-like Higgs with other particles can be subdominant to the same coming from the six dimensional operators. In this context, we revisit the alignment limit itself. It is investigated to what extent these operators can mask the actual alignment in a 2HDM. The bosonic operators which rescale the Higgs kinetic terms can lead to substantial change in the parameter space of the model. We find that some other bosonic operators, which are severely constrained from the electroweak precision tests, can also modify the parameter space of 2HDM due to their anomalous momentum structures. A particular kind of Little Higgs model is explored as an example of 2HDM effective field theory in connection with 2HDM alignment. Choosing a suitable benchmark point in a Type-II 2HDM, we highlight the possibility that the exact alignment limit is ruled out at 95% CL in presence of such operators.

    hep-phJHEP(2018)·9 citations
11. 11*

    Precision determination of the strong coupling constant within a global PDF analysis

    Richard D.Ball🇬🇧 · Stefano Carrazza🇨🇭 · Luigi Del Debbio🇬🇧 · Stefano Forte🇮🇹 · Zahari Kassabov🇬🇧 · Juan Rojo🇳🇱 · Emma Slade🇬🇧 · Maria Ubiali🇬🇧

    We present a determination of the strong coupling constant ${\alpha }_s(m_Z)$ based on the NNPDF3.1 determination of parton distributions, which for the first time includes constraints from jet production, top-quark pair differential distributions, and the $Z$ $p_T$ distributions using exact NNLO theory. Our result is based on a novel extension of the NNPDF methodology - the correlated replica method - which allows for a simultaneous determination of ${\alpha }_s$ and the PDFs with all correlations between them fully taken into account. We study in detail all relevant sources of experimental, methodological and theoretical uncertainty. At NNLO we find ${\alpha }_s(m_Z)=0.1185\pm 0.0005^{\text{(exp)}}\pm 0.0001^{\text{(meth)}}$, showing that methodological uncertainties are negligible. We conservatively estimate the theoretical uncertainty due to missing higher order QCD corrections (N${}^3$LO and beyond) from half the shift between the NLO and NNLO ${\alpha }_s$ values, finding $\Delta {\alpha }_s^{\mathrm{th}}=0.0011$.

    hep-phhep-exEPJC(2018)·89 citations
12. 12*

    DarkSUSY 6 : An Advanced Tool to Compute Dark Matter Properties Numerically

    Torsten Bringmann🇳🇴 · Joakim Edsjo🇸🇪 · Paolo Gondolo🇺🇸 · Piero Ullio🇮🇹 · Lars Bergstrom🇸🇪

    The nature of dark matter remains one of the key science questions. Weakly Interacting Massive Particles (WIMPs) are among the best motivated particle physics candidates, allowing to explain the measured dark matter density by employing standard big-bang thermodynamics. We introduce here a radically new version of the widely used DarkSUSY package, which allows to compute the properties of such dark matter particles numerically. With DarkSUSY 6 one can accurately predict a large variety of astrophysical signals from dark matter, such as direct detection rates in low-background counting experiments and indirect detection signals through antiprotons, antideuterons, gamma rays and positrons from the Galactic halo, or high-energy neutrinos from the center of the Earth or of the Sun. For thermally produced dark matter like WIMPs, high-precision tools are provided for the computation of the relic density in the Universe today, as well as for the size of the smallest dark matter protohalos. Furthermore, the code allows to calculate dark matter self-interaction rates, which may affect the distribution of dark matter at small cosmological scales. Compared to earlier versions, DarkSUSY 6 introduces many significant physics improvements and extensions. The most fundamental new feature of this release, however, is that the code has been completely re-organized and brought into a highly modular and flexible shape. Switching between different pre-implemented dark matter candidates has thus become straight-forward, just as adding new - WIMP or non-WIMP - particle models or replacing any given functionality in a fully user-specified way. In this article, we describe the physics behind the computer package, along with the main structure and philosophy of this major revision of DarkSUSY. A detailed manual is provided together with the public release at www.darksusy.org.

    hep-phastro-ph.COJCAP(2018)·223 citations
13. 13*

    Production cross sections of cosmic antiprotons in the light of new data from the NA61 and LHCb experiments

    Michael Korsmeier🇩🇪 · Fiorenza Donato🇮🇹 · Mattia Di Mauro🇺🇸

    The cosmic-ray flux of antiprotons is measured with high precision by the space-borne particle spectrometers AMS-02.Its interpretation requires a correct description of the dominant production process for antiprotons in our Galaxy, namely, the interaction of cosmic-ray proton and helium with the interstellar medium. In the light of new cross section measurements by the NA61 experiment of $p+p\to \bar{p}+X$ and the first ever measurement of $p+\mathrm{He}\to \bar{p}+X$ by the LHCb experiment, we update the parametrization of proton-proton and proton-nucleon cross sections.We find that the LHCb $p$He data constrain a shape for the cross section at high energies and show for the first time how well the rescaling from the $pp$ channel applies to a helium target. By using $pp$, $p$He and $p$C data we estimate the uncertainty on the Lorentz invariant cross section for $p+\mathrm{He}\to \bar{p}+X$. We use these new cross sections to compute the source term for all the production channels, considering also nuclei heavier than He both in cosmic rays and the interstellar medium. The uncertainties on the total source term are at the level of $\pm 20$% and slightly increase below antiproton energies of 5 GeV. This uncertainty is dominated by the $p+p\to \bar{p}+X$ cross section, which translates into all channels since we derive them using the $pp$ cross sections. The cross sections to calculate the source spectra from all relevant cosmic-ray isotopes are provided in the Supplemental Material. We finally quantify the necessity of new data on antiproton production cross sections, and pin down the kinematic parameter space which should be covered by future data.

    ↳ astro-ph.HEhep-exhep-phPRD(2018)·99 citations
14. 14*

    Determination of $s$- and $p$-wave $I=1/2$ $K\pi$ scattering amplitudes in $N_{\mathrm{f}}=2+1$ lattice QCD

    Ruairí Brett🇺🇸 · John Bulava🇩🇰 · Jacob Fallica🇺🇸 · Andrew Hanlon🇩🇪 · Ben Hörz🇩🇪 · Colin Morningstar🇺🇸

    The elastic $I=1/2$, $s$- and $p$-wave kaon-pion scattering amplitudes are calculated using a single ensemble of anisotropic lattice QCD gauge field configurations with $N_{\mathrm{f}}=2+1$ flavors of dynamical Wilson-clover fermions at $m_{\pi }=230\mathrm{MeV}$. A large spatial extent of $L=3.7\mathrm{fm}$ enables a good energy resolution while partial wave mixing due to the reduced symmetries of the finite volume is treated explicitly.The $p$-wave amplitude is well described by a Breit-Wigner shape with parameters $m_{K^{\ast }}/m_{\pi }=3.808(18)$ and $g_{K^{\ast }K\pi }^{\mathrm{BW}}=5.33(20)$ which are insensitive to the inclusion of $d$-wave mixing and variation of the $s$-wave parametrization. An effective range description of the near-threshold $s$-wave amplitude yields $m_{\pi }{a}_0=-0.353(25)$.

    ↳ hep-lathep-phnucl-thNPB(2018)·82 citations
15. 15*

    Equivalence of One Loop Diagrams in Covariant and Light Front QED Revisited

    Deepesh Bhamre🇮🇳 · Anuradha Misra🇮🇳 · Vivek Kumar Singh🇮🇳

    We revisit the proof of equivalence of one loop expressions for fermion self-energy and vertex correction in light-front QED and Covariant QED at the Feynman diagram level and generalize, to all components, the proof of equivalence for the one loop vertex correction diagram which was presented earlier by us only for the $+$ component of ${\Lambda }^{\mu }$. We demonstrate, in the general case also, that the equivalence cannot be established without the third term in the three-term photon propagator in light cone gauge.

    ↳ hep-thhep-phFew Body Syst.(2018)·7 citations
16. 16*

    Vector-Interaction-Enhanced Bag Model

    Mateusz Cierniak🇵🇱 · Thomas Klähn🇺🇸 · Tobias Fischer🇵🇱 · Niels-Uwe Bastian🇵🇱

    A commonly applied quark matter model in astrophysics is the thermodynamic bag model (tdBAG). The original MIT bag model approximates the effect of quark confinement, but does not explicitly account for the breaking of chiral symmetry, an important property of Quantum Chromodynamics (QCD). It further ignores vector repulsion. The vector-interaction-enhanced bag model (vBag) improves the tdBAG approach by accounting for both dynamical chiral symmetry breaking and repulsive vector interactions. The latter is of particular importance to studies of dense matter in beta-equilibriumto explain the two solar mass maximum mass constraint for neutron stars. The model is motivated by analyses of QCD based Dyson-Schwinger equations (DSE), assuming a simple quark-quark contact interaction. Here, we focus on the study of hybrid neutron star properties resulting from the application of vBag and will discuss possible extensions.

    ↳ nucl-thastro-ph.HEhep-phUniverse(2018)·24 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.