Wed·Jun 7, 2017Wednesday·June 7, 2017

1. 01*

   Analysis of vector boson production within TMD factorization

   Ignazio Scimemi🇪🇸 · Alexey Vladimirov🇩🇪

   We present a comprehensive analysis and extraction of the unpolarized transverse momentum dependent (TMD) parton distribution functions, which are fundamental constituents of the TMD factorization theorem. We provide a general review of the theory of TMD distributions, and present a new scheme of scale fixation. This scheme, called the $\zeta$-prescription, allows to minimize the impact of perturbative logarithms in the large range of scales and does not generate undesired power corrections. Within $\zeta$-prescription we consistently include the perturbatively calculable parts up to next-to-next-to-leading order (NNLO), and perform the global fit of the Drell-Yan and Z-boson production, which include the data of E288, Tevatron and LHC experiments. The nonperturbative part of the TMDs are explored checking a large variety of models. We support the obtained results by a study of theoretical uncertainties, perturbative convergence, and dedicated study of the range of applicability of the TMD factorization theorem. The considered nonperturbative models present significant differences in the fitting behavior, which allow us to clearly disfavor most of them. The numerical evaluations are provided by the "arTeMiDe" code, which is introduced in this work and that can be used for current/future TMD phenomenology.

   hep-phhep-exhep-latnucl-ex+1EPJC(2018)·197 citations
2. 02*

   High- and low-energy constraints on top-Higgs couplings

   W. Dekens🇺🇸

   We study the five chirality-flipping interactions that appear in the top-Higgs sector at leading order in the standard model effective field theory. We consider constraints from collider observables, flavor physics, and electric-dipole-moment experiments. This analysis results in very competitive constraints from indirect observables when one considers a single coupling at a time. In addition, we discuss how these limits are affected in scenarios in which multiple top-Higgs interactions are generated at the scale of new physics.

   hep-phPoS(2017)·1 citation
3. 03*

   Information-entropic analysis of Korteweg--de Vries solitons in the quark-gluon plasma

   A. Goncalves da Silva🇧🇷 · R. da Rocha🇧🇷

   Solitary waves propagation of baryonic density perturbations, ruled by the Korteweg--de Vries equation in a mean-field quark-gluon plasma model, are investigated from the point of view of the theory of information. A recently proposed continuous logarithmic measure of information, called configurational entropy, is used to derive the soliton width, defining the pulse, for which the informational content of the soliton spatial profile is more compressed, in the Shannon's sense.

   hep-phhep-latnlin.PSPLB(2017)·32 citations
4. 04*

   Searching for the heavy custodial fiveplet Higgs in the Georgi-Machacek model at the International Linear Collider

   YuFei Zhang🇨🇳 · Hao Sun🇨🇳 · Xuan Luo🇨🇳 · WeiNing Zhang🇨🇳

   The Georgi-Machacek (GM) model is one of many Beyond Standard Model scenarios with an extended scalar sector which can group under the custodial $\mathrm{SU}(2{)}_{\mathrm{C}}$ symmetry into a fiveplet, a triplet, and two singlets. The heavy charged custodial fiveplet Higgs ${\mathrm{H}}_5^{\pm }$ are typical particles in GM model which couple to the electroweak gauge bosons, therefore provide a good testing ground for the detection of the ${\mathrm{H}}^{\pm }{\mathrm{W}}^{\mp }\mathrm{Z}$ vertex. The neutral custodial fiveplet Higgs ${\mathrm{H}}_5^0$ in the GM model has the same mass with ${\mathrm{H}}_5^{\pm }$ and couples to the electroweak gauge bosons ${\mathrm{W}}^{+}{\mathrm{W}}^{-}$ and ZZ both. We study the discovery prospects of the exotic scalar bosons ${\mathrm{H}}_5^{\pm }$ and ${\mathrm{H}}_5^0$ at the International Linear Collider(ILC) via the vector boson associated production processes, and discuss two different decay modes for both charged and neutral scalars. The discovery potential is discussed. Testing the mass degeneracy of charged and neutral scalar bosons in the GM model is also considered.

   hep-phPRD(2017)·14 citations
5. 05*

   Asymmetry Observables for Measuring Spin Correlations in Top-Quark Pair Production

   Kai Ma🇨🇳

   Spin correlations between top-quark and anti-top-quark in pair production are sensitive to physics beyond the standard model. A complete set of observables, that can be used to measure all independent parameters of the production spin density matrix, is necessary to search for anomalous interactions in the production dynamics. In this letter, we provide a set of asymmetry observables for measuring all the density matrix elements. These observables are defined regardless of the production mechanism, and can be specified in any desired reference frame, particularly the laboratory frame in which the first evidence of spin correlation was observed experimentally. Our method can be used to find an optimal Lorentz frame in which the sensitivity to the density matrices is high for given production process and experimental environment, or to test possible correlations among the matrix elements.

   hep-phPRD(2017)·5 citations
6. 06*

   $\Delta N_{\text{eff}}$ and entropy production from early-decaying gravitinos

   Emanuela Dimastrogiovanni (1,2)🇺🇸 · Lawrence M. Krauss (2,3) ((1) Case Western Reserve University, (2) Arizona State University, (3) Australian National University)🇺🇸

   Gravitinos are a fundamental prediction of supergravity, their mass ($m_G$) is informative of the value of the SUSY breaking scale, and, if produced during reheating, their number density is a function of the reheating temperature ($T_{\text{rh}}$). As a result, constraining their parameter space provides in turn significant constraints on particles physics and cosmology. We have previously shown that for gravitinos decaying into photons or charged particles during the ($\mu$ and $y$) distortion eras, upcoming CMB spectral distortions bounds are highly effective in constraining the $T_{\text{rh}}-m_G$ space. For heavier gravitinos (with lifetimes shorter than a few $\times 10^6$ sec), distortions are quickly thermalized and energy injections cause a temperature rise for the CMB bath. If the decay occurs after neutrino decoupling, its overall effect is a suppression of the effective number of relativistic degrees of freedom ($N_{\text{eff}}$). In this paper, we utilize the observational bounds on $N_{\text{eff}}$ to constrain gravitino decays, and hence provide new constaints on gravitinos and reheating. For gravitino masses less than $\approx 10^5$ GeV, current observations give an upper limit on the reheating scale in the range of $\approx 5\times 10^{10}-5\times 10^{11}$GeV. For masses greater than $\approx 4\times 10^3$ GeV they are more stringent than previous bounds from BBN constraints, coming from photodissociation of deuterium, by almost 2 orders of magnitude.

   hep-phastro-ph.COhep-thPRD(2018)·5 citations
7. 07*

   Gauged Q-ball Decay Rates into Fermions

   Jeong-Pyong Hong🇯🇵 · Masahiro Kawasaki🇯🇵

   We derive the decay rate of a gauged Q-ball into fermions, applying the leading semi-classical approximation. We find that more particles come out from the surface of a gauged Q-ball, compared to the case of a global Q-ball, due to the electric repulsion. We show that, however, the decay rate of a gauged Q-ball is bounded from above due to the Pauli blocking at the surface of the Q-ball, just as in the case of a global Q-ball. We also find that there is a further suppression due to the Coulomb potential outside the Q-ball, which we find to play the role of a potential barrier for the fermions coming from the inside the Q-ball.

   hep-phPRD(2017)·6 citations
8. 08*

   Studying the bound state of the $K^{-}p$ system in the Bethe-Salpeter formalism

   Chao Wang🇨🇳 · Liang-liang Liu🇨🇳 · Xin-Heng Guo🇨🇳

   We study the $s$-wave kaon-nucleon bound state with the strangeness $S=-1$ in the Bethe-Salpeter formalism in the ladder and instantaneous approximations. We solve the Bethe-Salpeter equation of the bound state and obtain the Bethe-Salpeter amplitude. It is shown that the $K^{-}p$ bound state exists in this formalism. We also study the decay width of the bound state based on the Bethe-Salpeter techniques. The mass of this bound state is 1422 MeV and its decay width is obviously smaller than that of $\Lambda (1405)$. These results indicate that there may be some other structures in the observed resonance.

   hep-phPRD(2017)·5 citations
9. 09*

   Higher order corrections in the CoLoRFulNNLO framework

   Gábor Somogyi🇭🇺 · Adam Kardos🇭🇺 · Zoltán Szőr🇭🇺 · Zoltán Trócsányi🇭🇺

   We discuss the CoLoRFulNNLO method for computing higher order radiative corrections to jet cross sections in perturbative QCD. We apply our method to the calculation of event shapes and jet rates in three-jet production in electron-positron annihilation. We validate our code by comparing our predictions to previous results in the literature and present the jet cone energy fraction distribution at NNLO accuracy. We also present preliminary NNLO results for the three-jet rate using the Durham jet clustering algorithm matched to resummed predictions at NLL accuracy, and a comparison to LEP data.

   hep-phActa Phys.Polon.B(2017)·3 citations
10. 10*

    Accessing the gluon Wigner distribution in ultraperipheral $pA$ collisions

    Yoshikazu Hagiwara🇯🇵 · Yoshitaka Hatta🇯🇵 · Roman Pasechnik🇸🇪 · Marek Tasevsky🇨🇿 · Oleg Teryaev🇷🇺

    We propose to constrain the gluon Wigner distribution in the nucleon by studying the exclusive diffractive dijet production process in ultraperipheral proton-nucleus collisions (UPCs) at RHIC and the LHC. Compared to the previous proposal in Ref. [Y. Hatta, B. W. Xiao, and F. Yuan, Phys. Rev. Lett. 116, 202301 (2016).] to study the same observable in lepton-nucleon scattering, the use of UPCs has a few advantages: not only is the cross section larger, but the extraction of the Wigner distribution from the data also becomes simpler, including its elliptic angular dependence. We compute the corresponding cross section and evaluate the coefficients using models which include the gluon saturation effects. A potential for the measurements of the Wigner distribution at current and future experimental facilities is also discussed.

    hep-phPRD(2017)·103 citations
11. 11*

    Polarisations of the $Z$ and $W$ bosons in the processes $pp\to ZH$ and $pp\to W_{}^{\pm }H$

    Junya Nakamura🇩🇪

    The $Z$ boson in the process $pp\to ZH$ and the $W_{}^{+}$ and $W_{}^{-}$ in the process $pp\to W_{}^{\pm }H$ can be in polarised states. The polarisation density matrix of the $Z$ ($W$) boson contains the complete information about a state of polarisation of the $Z$ ($W$) boson, and $HZZ$, $HZ\gamma$ and $HWW$ interactions may be studied in detail from a careful analysis of these matrices. In this paper, a systematic approach to analyse these polarisation density matrices is presented. With the aim of making maximum use of the polarisation information, all of the elements of the polarisation density matrices are related with observables, which are measurable at the environment of $pp$ collisions. Consequences of non-standard $HZZ$, $HZ\gamma$ and $HWW$ interactions for these observables are discussed.

    hep-phhep-exJHEP(2017)·31 citations
12. 12*

    Application of the rescaling model at small Bjorken $x$ values

    A.V. Kotikov🇷🇺 · B.G. Shaikhatdenov🇷🇺 · Pengming Zhang🇨🇳

    The Bessel-inspired behavior of parton densities at small Bjorken $x$ values, obtained in the case of the flat initial conditions for DGLAP evolution equations, is used along with "frozen" and analytic modifications of the strong coupling constant to study the so-called EMC effect. Among other results, this approach allowed predicting small $x$ behavior of the gluon density in nuclei.

    hep-phPRD(2017)·21 citations
13. 13*

    What is the scale of new physics behind the $B$-flavour anomalies?

    Luca Di Luzio🇬🇧 · Marco Nardecchia🇨🇭

    Motivated by the recent hints of lepton flavour non-universality in $B$-meson semi-leptonic decays, we study the constraints of perturbative unitarity on the new physics interpretation of the anomalies in $b\to c\ell \bar{\nu }$ and $b\to s\ell \bar{\ell }$ transitions. Within an effective field theory approach we find that $2\to 2$ fermion scattering amplitudes saturate the unitarity bound below 9 TeV and 80 TeV, respectively for $b\to c\ell \bar{\nu }$ and $b\to s\ell \bar{\ell }$ transitions. Stronger bounds, up to few TeV, are obtained when the leading effective operators are oriented in the direction of the third generation, as suggested by flavour models. We finally address unitarity constraints on simplified models explaining the anomalies and show that the new physics interpretation is ruled out in a class of perturbative realizations.

    hep-phEPJC(2017)·149 citations
14. 14*

    Re-derived overclosure bound for the inert doublet model

    S. Biondini🇨🇭 · M. Laine🇨🇭

    We apply a formalism accounting for thermal effects (such as modified Sommerfeld effect; Salpeter correction; decohering scatterings; dissociation of bound states), to one of the simplest WIMP-like dark matter models, associated with an "inert" Higgs doublet. A broad temperature range T ~ M/20...M/10^4 is considered, stressing the importance and less-understood nature of late annihilation stages. Even though only weak interactions play a role, we find that resummed real and virtual corrections increase the tree-level overclosure bound by 1...18%, depending on quartic couplings and mass splittings.

    hep-phJHEP(2017)·51 citations
15. 15*

    What if gravity becomes really repulsive in the future?

    Imanol Albarran🇵🇹 · Mariam Bouhmadi-López🇪🇸 · João Morais🇪🇸

    The current acceleration of the Universe is one of the most puzzling issues in theoretical physics nowadays. We are far from giving an answer on this letter to its true nature. Yet, with the observations we have at hand, we analyse the different patterns that the gravitational potential can show in the future. Surprisingly, gravity not only can get weaker in the near future, it can even become repulsive; or equivalently, the gravitational potential may become negative. We show this remark by using one of the simplest phenomenological model we can imagine for dark energy. We have as well reviewed the statefinder approach of these models. For completeness, we have also showed the behaviour of the density contrast of dark matter and dark energy for these simple (yet illustrative models). Our results are displayed at present and how they evolve in the future.

    ↳ gr-qcastro-ph.COhep-phhep-thEPJC(2018)·9 citations
16. 16*

    Sensitivity of the Cherenkov Telescope Array to the detection of a dark matter signal in comparison to direct detection and collider experiments

    Csaba Balázs🇦🇺 · Jan Conrad🇸🇪 · Ben Farmer🇸🇪 · Thomas Jacques🇮🇹 · Tong Li🇦🇺 · Manuel Meyer🇺🇸 · Farinaldo S. Queiroz🇩🇪 · Miguel A. Sánchez-Conde🇸🇪

    Imaging atmospheric Cherenkov telescopes (IACTs) that are sensitive to potential $\gamma$-ray signals from dark matter (DM) annihilation above $\sim 50$ GeV will soon be superseded by the Cherenkov Telescope Array (CTA). CTA will have a point source sensitivity an order of magnitude better than currently operating IACTs and will cover a broad energy range between 20 GeV and 300 TeV. Using effective field theory and simplified models to calculate $\gamma$-ray spectra resulting from DM annihilation, we compare the prospects to constrain such models with CTA observations of the Galactic center with current and near-future measurements at the Large Hadron Collider (LHC) and direct detection experiments. For DM annihilations via vector or pseudoscalar couplings, CTA observations will be able to probe DM models out of reach of the LHC, and, if DM is coupled to standard fermions by a pseudoscalar particle, beyond the limits of current direct detection experiments.

    ↳ astro-ph.HEhep-phPRD(2017)·37 citations
17. 17*

    Compact stars with sequential QCD phase transitions

    Mark G. Alford (1) · Armen Sedrakian (2) ((1) Physics Department · Washington University · St. Louis · (2) Frankfurt Institute for Advanced Studies)

    Compact stars may contain quark matter in their interiors at densities exceeding several times the nuclear saturation density. We explore models of such compact stars where there are two first-order phase transitions: the first from nuclear matter to a quark-matter phase, followed at higher density by another first-order transition to a different quark matter phase [e.g., from the two-flavor color superconducting (2SC) to the color-flavor-locked (CFL) phase). We show that this can give rise to two separate branches of hybrid stars, separated from each other and from the nuclear branch by instability regions and, therefore, to a new family of compact stars, denser than the ordinary hybrid stars. In a range of parameters, one may obtain twin hybrid stars (hybrid stars with the same masses but different radii) and even triplets where three stars, with inner cores of nuclear matter, 2SC matter, and CFL matter, respectively, all have the same mass but different radii.

    ↳ astro-ph.HEhep-phnucl-thPRL(2017)·195 citations
18. 18*

    Conserved charge fluctuations at vanishing and non-vanishing chemical potential

    Frithjof Karsch🇩🇪

    Up to 6th order cumulants of fluctuations of net baryon-number, net electric charge and net strangeness as well as correlations among these conserved charge fluctuations are now being calculated in lattice QCD. These cumulants provide a wealth of information on the properties of strong-interaction matter in the transition region from the low temperature hadronic phase to the quark-gluon plasma phase. They can be used to quantify deviations from hadron resonance gas (HRG) model calculations which frequently are used to determine thermal conditions realized in heavy ion collision experiments. Already some second order cumulants like the correlations between net baryon-number and net strangeness or net electric charge differ significantly at temperatures above 155 MeV in QCD and HRG model calculations. We show that these differences increase at non-zero baryon chemical potential constraining the applicability range of HRG model calculations to even smaller values of the temperature.

    ↳ hep-lathep-phhep-thNPA(2017)·18 citations
19. 19*

    Improved constraints on lepton asymmetry from the cosmic microwave background

    Isabel M. Oldengott🇩🇪 · Dominik J. Schwarz🇩🇪

    A cosmic lepton asymmetry ${\eta }_{\text{l}}=(n_{\text{l}}-n_{\bar{\text{l}}})/n_{\gamma }$ affects the primordial helium abundance and the expansion rate of the early Universe. Both of these effects have an impact on the anisotropies of the cosmic microwave background (CMB). We derive constraints on the neutrino chemical potentials from the Planck 2015 data, assuming equal lepton flavour asymmetries and negligible neutrino masses. We find $\xi =-0.002_{-0.111}^{+0.114}$ (95\% CL) for the chemical potentials, which corresponds to $-0.085\le {\eta }_{\text{l}}\le 0.084$. Our constraints on the lepton asymmetry are significantly stronger than previous constraints from CMB data analysis and we argue that they are more robust than those from primordial light element abundances. The resulting constraints on the primordial helium and deuterium abundances are consistent with those from direct measurements.

    ↳ astro-ph.COhep-phEPL(2017)·80 citations
20. 20*

    Theoretical predictions for dark matter detection in dwarf irregular galaxies with gamma rays

    V. Gammaldi🇮🇹 · E. V. Karukes🇧🇷 · P. Salucci🇮🇹

    We investigate dwarf irregular(dIrr) galaxies as a new category of targets for indirect Dark Matter(DM) searches with gamma-rays. In the framework of point-like analysis, dwarf spheroidal(dSph) galaxies are usually considered as one of the best category of targets for indirect DM searches. Nonetheless, as a result of their uncertain kinematics, the DM content and astrophysical J-factors of dSphs are usually affected by significant errors. In this paper, we study a sample of 36 dIrrs as prospective targets of interest. In the framework of the universal rotation curve, the kinematics of dIrr galaxies provides a good estimation of their DM halo density distribution and, consequently, of their astrophysical J-factors. We calculate the J-factors for these 36 dIrr galaxies. We find a range of values comparable with the J-factors of dSph galaxies. However, differently from dSphs an extra astrophysical gamma-ray background component is expected in dIrrs, that is due to their star-formation activity. In this paper, we show via a theoretical approach that for galaxies in our sample the extra astrophysical background component is negligible. Therefore, we conclude that dIrr galaxies can be potentially considered as additional point-like targets for DM searches with gamma-rays. As a first application of this study, we show the sensitivity limits of the Fermi-LAT telescope to these objects and we calculate constraints on the DM particle mass and annihilation cross-section. We conclude that the results of the individual study of several dIrr galaxies are not yet competitive with respect to the analysis of one of the most promising dSph galaxies, ie SEGUE1. However, taking into account SEGUE1's symmetry-related uncertainties in the J-factor calculation might alter this conclusion. Additionally, we calculate constraints for the combined analysis of the 7 most promising dIrr galaxies of our sample.

    ↳ astro-ph.COastro-ph.GAhep-phPRD(2018)·27 citations
21. 21*

    Failures of homogeneous and isotropic cosmologies in Extended Quasi-Dilaton Massive Gravity

    Stefano Anselmi🇫🇷 · Saurabh Kumar🇺🇸 · Diana López Nacir🇨🇭 · Glenn D. Starkman🇺🇸

    We analyze the Extended Quasi-Dilaton Massive Gravity model around a Friedmann-Lemaître-Robertson-Walker cosmological background. We present a careful stability analysis of asymptotic fixed points. We find that the traditional fixed point cannot be approached dynamically, except from a perfectly fine-tuned initial condition involving both the quasi-dilaton and the Hubble parameter. A less-well examined fixed-point solution, where the time derivative of the 0-th Stückelberg field vanishes ${\dot{\varphi }}^0=0$, encounters no such difficulty, and the fixed point is an attractor in some finite region of initial conditions. We examine the question of the presence of a Boulware-Deser ghost in the theory. We show that the additional constraint which generically allows for the elimination of the Boulware-Deser mode is only present under special initial conditions. We find that the only possibility corresponds to the traditional fixed point and the initial conditions are the same fine-tuned conditions that allow the fixed point to be approached dynamically.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2017)·14 citations
22. 22*

    Beyond-one-loop quantum gravity action yielding both inflation and late-time acceleration

    E. Elizalde🇪🇸 · S.D. Odintsov🇪🇸 · L.Sebastiani🇰🇿 · R.Myrzakulov🇰🇿

    A unified description of early-time inflation with the current cosmic acceleration is achieved by means of a new theory that uses a quadratic model of gravity, with the inclusion of an exponential $F(R)$-gravity contribution for dark energy. High-curvature corrections of the theory come from higher-derivative quantum gravity and yield an effective action that goes beyond the one-loop approximation. It is shown that, in this theory, viable inflation emerges in a natural way, leading to a spectral index and tensor-to-scalar ratio that are in perfect agreement with the most reliable Planck results. At low energy, late-time accelerated expansion takes place. As exponential gravity, for dark energy, must be stabilized during the matter and radiation eras, we introduce a curing term in order to avoid nonphysical singularities in the effective equation of state parameter. The results of our analysis are confirmed by accurate numerical simulations, which show that our model does fit the most recent cosmological data for dark energy very precisely.

    ↳ gr-qchep-phhep-thNPB(2017)·37 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.