Thu·Mar 8, 2018Thursday·March 8, 2018

1. 01*

   Higgs boson pair production at NNLO with top quark mass effects

   Massimiliano Grazzini🇨🇭 · Gudrun Heinrich🇩🇪 · Stephen Jones🇩🇪 · Stefan Kallweit🇨🇭 · Matthias Kerner🇩🇪 · Jonas M. Lindert🇬🇧 · Javier Mazzitelli🇨🇭

   We consider QCD radiative corrections to Higgs boson pair production through gluon fusion in proton collisions. We combine the exact next-to-leading order (NLO) contribution, which features two-loop virtual amplitudes with the full dependence on the top quark mass $M_t$, with the next-to-next-to-leading order (NNLO) corrections computed in the large-$M_t$ approximation. The latter are improved with different reweighting techniques in order to account for finite-$M_t$ effects beyond NLO. Our reference NNLO result is obtained by combining one-loop double-real corrections with full $M_t$ dependence with suitably reweighted real--virtual and double-virtual contributions evaluated in the large-$M_t$ approximation. We present predictions for inclusive cross sections in $pp$ collisions at $\sqrt{s}$=13, 14, 27 and 100TeV and we discuss their uncertainties due to missing $M_t$ effects. Our approximated NNLO corrections increase the NLO result by an amount ranging from +12% at $\sqrt{s}$=13TeV to +7% at $\sqrt{s}$=100TeV, and the residual uncertainty from missing $M_t$ effects is estimated to be at the few percent level. Our calculation is fully differential in the Higgs boson pair and the associated jet activity: we also present predictions for various differential distributions at $\sqrt{s}$=14 and 100TeV. Our results represent the most advanced perturbative prediction available to date for this process.

   hep-phJHEP(2018)·349 citations
2. 02*

   $\rho$ meson impact parameter distributions

   Bao-Dong Sun🇨🇳 · Yu-Bing Dong🇨🇳

   In this paper, the $\rho$ meson impact parameter dependent parton distributions and the impact parameter dependent form factors are introduced and discussed. By employing a Gaussian form wave packet, we calculate the impact parameter distributions of $\rho$ meson based on a light-front constituent quark model.

   hep-phCPC(2018)·7 citations
3. 03*

   Doubly hidden-charm/bottom $QQ\bar{Q}\bar{Q}$ tetraquark states

   Wei Chen🇨🇳 · Hua-Xing Chen🇨🇳 · Xiang Liu🇨🇳 · T. G. Steele🇨🇦 · Shi-Lin Zhu🇨🇳

   We study the mass spectra for the $cc\bar{c}\bar{c}$ and $bb\bar{b}\bar{b}$ tetraquark states by developing a moment sum rule method. Our results show that the $bb\bar{b}\bar{b}$ tetraquarks lie below the threshold of ${\eta }_b(1S){\eta }_b(1S)$. They are probably stable and very narrow. The masses for the doubly hidden-charm states $cc\bar{c}\bar{c}$ are higher than the spontaneous dissociation thresholds of two charmonium mesons. We suggest to search for such states in the $J/\psi J/\psi$ and ${\eta }_c(1S){\eta }_c(1S)$ channels.

   hep-phEPJ Web Conf.(2018)·23 citations
4. 04*

   Applied Holography of the AdS${}_5$-Kerr Spacetime

   Brett McInnes🇸🇬

   Asymptotically Anti-de Sitter Kerr black holes (we focus here on the five-dimensional case) are associated holographically with matter at conformal infinity which has a non-zero angular momentum density. It is natural to attempt to associate this angular momentum with the recently discovered vorticity of the plasmas produced in peripheral heavy-ion collisions. We assume that an AdS${}_5$-Kerr black hole with angular momentum to mass ratio $\mathcal{A}$ is dual to boundary matter with an angular momentum density to energy density ratio also equal to $\mathcal{A}$. With this assumption, we find that, for collisions corresponding to a given value of $\mathcal{A}$, there is a maximal possible angular velocity (well below the maximal value permitted by causality) for such matter at infinity, and that this value is in approximate agreement with the experimentally reported value of the average plasma vorticity produced in typical peripheral collisions of heavy ions.

   hep-phhep-thnucl-thInt.J.Mod.Phys.A(2019)·21 citations
5. 05*

   Study of the $B_s$ $\to$ $\varphi f_0(980)$ $\to$ $\varphi {\pi }^{+}{\pi }^{-}$ decay with perturbative QCD approach

   Na Wang🇨🇳 · Qin Chang🇨🇳 · Yueling Yang🇨🇳 · Junfeng Sun🇨🇳

   The rare cascade $B_s$ $\to$ $\varphi f_0(980)$ $\to$ $\varphi {\pi }^{+}{\pi }^{-}$ decay is studied with the perturbative QCD approach based on the formula for the quasi two-body decay, where the two-pion pair originates from the $S$-wave resonant $f_0(980)$ state. It is found that with the introduction of the nonperturbative two-pion distribution amplitudes and the Flatté parameterization of the scalar form factor for the $f_0(980)$ resonance, the branching ratio in the mass range 400 MeV $<$ $m({\pi }^{+}{\pi }^{-})$ $<$ 1600 MeV is ${\mathcal{B}}_{\mathrm{theo}}(B_s^0\to \varphi f_0(980)\to \varphi {\pi }^{+}{\pi }^{-})$ $=$ $[1.31_{-0.31}^{+0.40}(a_{\pi \pi }){}_{-0.16}^{+0.19}(m_b){}_{-0.09}^{+0.10}(\text{CKM})]\times 10^{-6}$, where the uncertainties come from the parameter $a_{\pi \pi }$ of the two-pion distribution amplitudes, the $b$ quark mass $m_b$, the Cabibbo-Kobayashi-Maskawa (CKM) factors, respectively. This result agrees with the recent LHCb measurement within uncertainties, ${\mathcal{B}}_{\exp }(B_s^0\to \varphi f_0(980)\to \varphi {\pi }^{+}{\pi }^{-})$ $=$ $(1.12\pm 0.16_{-0.08}^{+0.09}\pm 0.11)\times 10^{-6}$, where the errors are statistical, systematic and from the normalization, respectively.

   hep-phJ.Phys.G(2019)·17 citations
6. 06*

   Mapping the sensitivity of hadronic experiments to nucleon structure

   Bo-Ting Wang🇺🇸 · T. J. Hobbs🇺🇸 · Sean Doyle🇺🇸 · Jun Gao🇨🇳 · Tie-Jiun Hou🇨🇳 · Pavel M. Nadolsky🇺🇸 · Fredrick I. Olness🇺🇸

   Determinations of the proton's collinear parton distribution functions (PDFs) are emerging with growing precision due to increased experimental activity at facilities like the Large Hadron Collider. While this copious information is valuable, the speed at which it is released makes it difficult to quickly assess its impact on the PDFs, short of performing computationally expensive global fits. As an alternative, we explore new methods for quantifying the potential impact of experimental data on the extraction of proton PDFs. Our approach relies crucially on the Hessian correlation between theory-data residuals and the PDFs themselves, as well as on a newly defined quantity --- the sensitivity --- which represents an extension of the correlation and reflects both PDF-driven and experimental uncertainties. This approach is realized in a new, publicly available analysis package PDFSense, which operates with these statistical measures to identify particularly sensitive experiments, weigh their relative or potential impact on PDFs, and visualize their detailed distributions in a space of the parton momentum fraction $x$ and factorization scale $\mu$. This tool offers a new means of understanding the influence of individual measurements in existing fits, as well as a predictive device for directing future fits toward the highest impact data and assumptions. Along the way, many new physics insights can be gained or reinforced. As one of many examples, PDFSense is employed to rank the projected impact of new LHC measurements in jet, vector boson, and $t\bar{t}$ production and leads us to the conclusion that inclusive jet production at the LHC has a potential for playing an indispensable role in future PDF fits. These conclusions are independently verified by preliminarily fitting this experimental information and investigating the constraints they supply using the Lagrange multiplier technique.

   hep-phhep-exnucl-thPRD(2018)·47 citations
7. 07*

   Severely Constraining Dark Matter Interpretations of the 21-cm Anomaly

   Asher Berlin🇺🇸 · Dan Hooper🇺🇸 · Gordan Krnjaic🇺🇸 · Samuel D. McDermott🇺🇸

   The EDGES Collaboration has recently reported the detection of a stronger-than-expected absorption feature in the global 21-cm spectrum, centered at a frequency corresponding to a redshift of z ~ 17. This observation has been interpreted as evidence that the gas was cooled during this era as a result of scattering with dark matter. In this study, we explore this possibility, applying constraints from the cosmic microwave background, light element abundances, Supernova 1987A, and a variety of laboratory experiments. After taking these constraints into account, we find that the vast majority of the parameter space capable of generating the observed 21-cm signal is ruled out. The only range of models that remains viable is that in which a small fraction, ~ 0.3-2%, of the dark matter consists of particles with a mass of ~ 10-80 MeV and which couple to the photon through a small electric charge, epsilon ~ 10^{-6}-10^{-4}. Furthermore, in order to avoid being overproduced in the early universe, such models must be supplemented with an additional depletion mechanism, such as annihilations through a L_{\mu}-L_{\tau} gauge boson or annihilations to a pair of rapidly decaying hidden sector scalars.

   hep-phastro-ph.COastro-ph.GAastro-ph.HE+1PRL(2018)·288 citations
8. 08*

   A new solar neutrino channel for grand-unification monopole searches

   Nick Houston🇨🇳 · Tianjun Li🇨🇳 · Chen Sun🇨🇳

   We identify a previously untapped discovery channel for grand-unification monopoles, arising from their ability to catalyse the direct decay of protons into monoenergetic 459 MeV antineutrinos within the Sun. Previous analyses omit this possibility as it necessarily involves an electroweak suppression factor, and instead search for the unsuppressed 20-50 MeV neutrinos produced via two-stage proton decays. By accounting for the relative difference in interaction cross section and experimental background at typical neutrino detection experiments, we demonstrate that this new channel in fact possesses greater discovery potential. As a case in point, using 5326 live days of Super-Kamiokande exposure we find that $2\sigma$ ($3\sigma$) deviations in the 20-50 MeV channel are amplified to $3\sigma$ ($4.6\sigma$) deviations in the 459 MeV case. Exploiting correlations between these two channels may also offer even greater statistical power.

   hep-phastro-ph.HEastro-ph.SRJCAP(2018)·3 citations
9. 09*

   Placing the newly observed state $B_J(5840)$ in bottom spectra along with states $B_1(5721)$, $B_2^{\ast }(5747)$, $B_{s1}(5830)$, $B_{2s}^{\ast }(5840)$ and $B_J(5970)$

   Pallavi Gupta🇮🇳 · A. Upadhyay🇮🇳

   In this article, we study the two body strong decays with the emission of light pseudo-scalar mesons $(\pi ,\eta ,K)$ for higher excited bottom states with in the framework of HQET. Inspired from the recent observation of bottom meson $B_J(5840)$ by LHCb collaboration \cite{9}, we classify the six possible $J^P$'s for this state on the basis of the theoretically available masses. By analyzing the strong decay widths and the branching ratios for all these six cases of $B_J(5840)$, we justify one of them to be the most favorable assignment for it. We also examined the recently observed bottom state $B_J(5970)$ as 2S$1^{-}$ and states $B_J(5721)$ and $B_2^{\ast }(5747)$ with their strange partners $B_{s1}(5830)$ and $B_{2s}^{\ast }(5840)$ for their $J^P$'s as $1P_{3/2}{1}^{+}$ and $1P_{3/2}{2}^{+}$ respectively. The predicted coupling constants $g_{XH}$, ${\tilde{g}}_{HH}$ and $g_{TH}$ helps in redeeming the strong decay width of experimentally missing bottom states $B(2^1{S}_0)$, $B_s(2^3{S}_1)$, $B_s(2^1{S}_0)$, $B(1^1{D}_2)$, $B_s(1^3{D}_1)$ and $B_s(1^1{D}_2)$. These predictions provide a crucial information for upcoming experimental studies.

   hep-phPRD(2019)·13 citations
10. 10*

    Constraining Density Fluctuations with Big Bang Nucleosynthesis in the Era of Precision Cosmology

    John D. Barrow🇬🇧 · Robert J. Scherrer🇺🇸

    We reexamine big bang nucleosynthesis with large-scale baryon density inhomogeneities when the length scale of the density fluctuations exceeds the neutron diffusion length ($\sim 10^7-10^8$ cm at BBN), and the amplitude of the fluctuations is sufficiently small to prevent gravitational collapse. In this limit, the final light element abundances can be determined by simply mixing the abundances from regions with different baryon/photon ratios without interactions. We examine gaussian, lognormal, and gamma distributions for the baryon/photon ratio, $\eta$. We find that the deuterium and lithium-7 abundances increase with the RMS fluctuation in $\eta$, while the effect on helium-4 is much smaller. We show that these increases in the deuterium and lithium-7 abundances are a consequence of Jensen's inequality, and we derive analytic approximations for these abundances in the limit of small RMS fluctuations. Observational upper limits on the primordial deuterium abundance constrain the RMS fluctuation in $\eta$ to be less than $17\%$ of the mean value of $\eta$. This provides us with a new limit on the graininess of the early universe.

    ↳ astro-ph.COgr-qchep-phPRD(2018)·15 citations
11. 11*

    Gravitational radiation from the classical spinning double copy

    Jingping Li🇺🇸 · Siddharth G. Prabhu🇺🇸

    We establish a correspondence between perturbative classical gluon and gravitational radiation emitted by spinning sources, to linear order in spin. This is an extension of the non-spinning classical perturbative double copy and uses the same color-to-kinematic replacements. The gravitational theory has a scalar (dilaton) and a 2-form field (the Kalb-Ramon axion) in addition to the graviton. In arXiv:1712.09250, we computed axion radiation in the gravitational theory to show that the correspondence fixes its action. Here, we present complete details of the gravitational computation. In particular, we also calculate the graviton and dilaton amplitudes in this theory and find that they precisely match with the predictions of the double copy. This constitutes a non-trivial check of the classical double copy correspondence, and brings us closer to the goal of simplifying the calculation of gravitational wave observables for astrophysically relevant sources.

    ↳ hep-thgr-qchep-phPRD(2018)·81 citations
12. 12*

    Sudden Future Singularities and their observational signatures in Modified Gravity

    Andreas Lymperis🇬🇷

    We verify the existence of Generalized Sudden Future Singularities (GSFS) in quintessence models with scalar field potential of the form $V(\varphi )\sim |\varphi {|}^n$ where $0<n<1$ and in the presence of a perfect fluid, both numerically and analytically, using a proper generalized expansion ansatz for the scale factor and the scalar field close to the singularity. This generalized ansatz includes linear and quadratic terms, which dominate close to the singularity and cannot be ignored when estimating the Hubble parameter and the scalar field energy density; as a result, they are important for analysing the observational signatures of such singularities. We derive analytical expressions for the power (strength) of the singularity in terms of the power $n$ of the scalar field potential. We then extend the analysis to the case of scalar tensor quintessence models with the same scalar field potential in the presence of a perfect fluid, and show that a Sudden Future Singularity (SFS) occurs in this case. We derive both analytically and numerically the strength of the singularity in terms of the power $n$ of the scalar field potential.

    ↳ gr-qchep-phhep-thPoS(2018)·3 citations
13. 13*

    Two-zone diffusion of electrons and positrons from Geminga explains the positron anomaly

    Kun Fang🇨🇳 · Xiao-Jun Bi🇨🇳 · Peng-Fei Yin🇨🇳 · Qiang Yuan🇨🇳

    The recent HAWC observations of very-high-energy $\gamma$-ray halo around Geminga and Monogem indicate a very slow diffusion of cosmic rays, which results in tiny contribution of positrons from these two pulsars to the local flux. This makes the cosmic positron excess anomaly observed by PAMELA and AMS-02 even more puzzling. However, from the Boron-to-Carbon ratio data one can infer that the average diffusion coefficient in the Galaxy should be much larger. In this work we propose a two-zone diffusion model that the diffusion is slow only in a small region around the source, outside of which the propagation is as fast as usual. We find that such a scenario can naturally explain the positron excess data with parameters even more reasonable than that in the conventional one-zone diffusion model. The reason is that during the life time of Geminga ($\sim 300$ kyr) the electrons/positrons have propagated too far away with a fast diffusion and lead to a low local flux. The slow diffusion region in the two-zone model helps to confine the electrons/positrons for a long time and lead to an enhancement of the local flux. So under the constraint of the HAWC observations, pulsars are still the probable origin of the cosmic-ray positron excess.

    ↳ astro-ph.HEhep-phApJ(2018)·114 citations
14. 14*

    Reconstruction of light-cone parton distribution functions from lattice QCD simulations at the physical point

    Constantia Alexandrou🇨🇾 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Karl Jansen🇩🇪 · Aurora Scapellato🇨🇾 · Fernanda Steffens🇩🇪

    We present the unpolarized and helicity parton distribution functions calculated within lattice QCD simulations using physical values of the light quark mass. Non-perturbative renormalization is employed and the lattice data are converted to the MSbar-scheme at a scale of 2 GeV. A matching process is applied together with target mass corrections leading to the reconstruction of light-cone parton distribution functions. For both cases we find a similar behavior between the lattice and phenomenological data, and for the polarized PDF a nice overlap for a range of Bjorken-x values. This presents a major success for the emerging field of direct calculations of quark distributions using lattice QCD.

    ↳ hep-lathep-exhep-phnucl-thPRL(2018)·206 citations
15. 15*

    Distribution of primordial black holes and 21cm signature

    Jinn-Ouk Gong🇰🇷 · Naoya Kitajima🇯🇵

    We show that the number of primordial black holes (PBHs) which is originated from primordial density perturbations with moderately-tilted power spectrum fluctuates following the log-normal distribution, while it follows the Poisson distribution if the spectrum is steeply blue. The log-normal, as well as the Poisson, fluctuation of the PBH number behaves as an isocurvature mode and affects the matter power spectrum and the halo mass function in a different way from those for the Poisson case. The future 21cm observation can potentially put a stronger constraint on the PBH fraction than the current one in a wide mass range, $10^{-5}{M}_{\odot }$--$10M_{\odot }$.

    ↳ astro-ph.COgr-qchep-phJCAP(2018)·22 citations
16. 16*

    Primordial Black Holes from String Inflation

    Michele Cicoli🇮🇹 · Victor A. Diaz🇮🇹 · Francisco G. Pedro🇮🇹

    We present a single-field string inflationary model which allows for the generation of primordial black holes in the low mass region where they can account for a significant fraction of the dark matter abundance. The potential is typical of type IIB fibre inflation models and features a plateau at CMB scales and a near inflection point at large distance scales where the power spectrum is enhanced due to a period of ultra slow-roll. The tunability of the underlying parameters is guaranteed by scanning through the string landscape and their stability against quantum corrections is ensured by an effective shift symmetry.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2018)·165 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.