Thu·Jan 19, 2017Thursday·January 19, 2017

1. 01*

   Cosmic Ray Antiprotons at High Energies

   Martin Wolfgang Winkler🇸🇪

   Cosmic ray antiprotons provide a powerful tool to probe dark matter annihilations in our galaxy. The sensitivity of this important channel is, however, diluted by sizable uncertainties in the secondary antiproton background. In this work, we improve the calculation of secondary antiproton production with a particular focus on the high energy regime. We employ the most recent collider data and identify a substantial increase of antiproton cross sections with energy. This increase is driven by the violation of Feynman scaling as well as by an enhanced strange hyperon production. The updated antiproton production cross sections are made publicly available for independent use in cosmic ray studies. In addition, we provide the correlation matrix of cross section uncertainties for the AMS-02 experiment. At high energies, the new cross sections improve the compatibility of the AMS-02 data with a pure secondary origin of antiprotons in cosmic rays.

   hep-phastro-ph.HEhep-exJCAP(2017)·98 citations
2. 02*

   $K\pi$ $I=1/2$ $S$-wave from ${\eta }_c$ decay data at BaBar and classic Meson-Meson scattering from LASS

   A. Palano🇮🇹 · M.R. Pennington🇺🇸

   A recent analysis of data on the two photon production of the ${\eta }_c$ and its decay to $K(K\pi )$ has determined the $K\pi$ $S$-wave amplitude in a "model-independent" way assuming primarily that the additional kaon is a spectator in this decay. The purpose of this paper is to fit these results, together with classic $K\pi$ production data from LASS, within a formalism that implements unitarity for the di-meson interaction. This fixes the $I=1/2$ $K\pi \to K\pi$ $S$-wave amplitude up to 2.4 GeV. This resolves the Barrelet ambiguity in the original LASS analysis, and constrains the amount of inelasticity in $K\pi$ scattering, highlighting that this becomes significant beyond 1.8 GeV. This result needs to be checked by experimental information on the many inelastic channels, in particular $K{\eta }^{\prime }$ and $K\pi \pi \pi$. Our analysis provides a single representation for the $K\pi$ $S$-wave from threshold, controlled by Chiral Perturbation Theory, through the broad $\kappa$, $K_0^{\ast }(1430)$ and $K_0^{\ast }(1950)$ resonances. There is no arbitrary sum of Breit-Wigner forms and random backgrounds for real $K\pi$ masses. Rather the form provides a representation that can be translated to other processes with $K\pi$ interactions with their own coupling functions, while automatically maintaining consistency with the chiral dynamics near threshold, with the LASS data and the new results on ${\eta }_c$ decay.

   hep-phhep-exnucl-th5 citations
3. 03*

   Probing Radiative Neutrino Mass Models At The LHC Via Trilepton Events

   Dounia Cherigui🇩🇿 · Chahrazed Guella🇩🇿 · Amine Ahriche🇩🇿 · Salah Nasri🇦🇪

   Trilepton event represents one of the probes of the new physics at high energy colliders. In this talk, we consider the search for processes with final states ${\ell }_{\alpha }^{\pm }{\ell }_{\beta }^{\pm }{\ell }_{\gamma }^{\mp }$ + $\text{slashed}{E}_T$ where $\alpha$, $\beta$, $\gamma$= $e,\mu ,\tau$, via the production of singlet charged scalar $S^{\pm }$ which arise in a class of radiative neutrino mass models. We discuss the opposite sign same flavor leptons signal, as well as the background free channel in view to get a significant excess at $\sqrt{s}$= 8 TeV and $\sqrt{s}$ = 14 TeV at the hadron collider LHC.

   hep-ph0 citations
4. 04*

   Standard Model with hidden scale invariance and light dilaton

   Archil Kobakhidze🇦🇺 · Shelley Liang🇦🇺

   We consider the minimal Standard Model as an effective low-energy description of an unspecified fundamental theory with spontaneously broken conformal symmetry. The effective theory exhibits classical scale invariance which manifest itself through the dilaton field. The mass of the dilaton is generated via the quantum scale anomaly at two-loop level and is proportional to the techically stable hierarchy between the electroweak scale and a high energy scale given by a dilaton vacuum expectation value. We find that a generic prediction of this class of models is the existence of a very light dilaton with mass between $\sim 0.01$ $\mu$eV to $\sim 100$ MeV, depending on the hierarchy of scales. Searches for such a light scalar particle may reveal a fundamental role of conformal invariance in nature.

   hep-phhep-th10 citations
5. 05*

   Strange quark-antiquark asymmetry of nucleon sea from $\Lambda /\bar{\Lambda }$ polarization

   Xiaozhen Du🇨🇳 · Bo-Qiang Ma🇨🇳

   Distinctions between quark to $\Lambda$ and $\bar{\Lambda }$ longitudinal spin transfers in the semi-inclusive deep inelastic scattering process were observed by the E665 and COMPASS Collaborations. There are suggestions that the difference between $\Lambda$ and $\bar{\Lambda }$ production is related to the asymmetric strange-antistrange distribution inside the nucleon. However, previous calculations are still too small to explain the experimental data. From a realistic consideration of quark to $\Lambda$ fragmentation due to different flavors, we investigate the strange quark contribution for $\Lambda$ production and polarization. We find that the strange quark-antiquark asymmetry of the nucleon sea can be amplified into an observable quantity from the difference between $\Lambda$ and $\bar{\Lambda }$ polarizations after taking into account the larger probability of the $\Lambda$ produced from the $s$ quark fragmentation process compared to that from the $u$ or $d$ quark. The qualitative agreement between our calculation and the experimental data supports the existence of the intrinsic strange sea and the strange-antistrange asymmetry. Thus the polarization of $\Lambda /\bar{\Lambda }$ does open a new window to probe the nucleon sea properties, especially the strange content and its quark-antiquark asymmetry.

   hep-phhep-exPRD(2017)·8 citations
6. 06*

   Pair production of heavy neutrinos in next-to-leading order QCD at the hadron colliders in the inverse seesaw framework

   Arindam Das🇰🇷

   The explanation of the small neutrino mass can be depicted using some handsome models like type-I and inverse seesaw where the Standard Model gauge singlet heavy right handed neutrinos are deployed. The common thing in these two models is a lepton number violating parameter, however, its order of magnitude creates a striking difference between them making the nature of the right handed heavy neutrinos a major play factor. In the type-I seesaw a large lepton number violating parameter involves the heavy right handed neutrinos in the form of Majorana fermions while a small lepton number violating parameter being involved in the inverse seesaw demands the pseudo-Dirac nature of the heavy right handed neutrinos. Such heavy neutrinos are accommodated in these models through the sizable mixings with the Standard Model light neutrinos. In this paper we consider the purely inverse seesaw scenario to study the pair production of the pseudo-Dirac heavy neutrinos followed by their various multilepton decay modes through the leading branching fraction at the Leading Order and Next-to-Leading Order QCD at the LHC with a center of mass energy of 13 TeV and a luminosity of 3000 fb${}^{-1}$. We also consider a prospective 100 TeV hadron collider with luminosities of 3000 fb${}^{-1}$ and 30000 fb${}^{-1}$ respectively to study the process. Using anomalous multilepton search performed by the CMS at the 8 TeV with 19.5 fb${}^{-1}$ luminosity we show prospective search reaches of the mixing angles for the three lepton and four lepton events at the 13 TeV LHC and 100 TeV hadron collider.

   hep-phhep-exInt.J.Mod.Phys.A(2021)·40 citations
7. 07*

   Heavy neutral scalar decays into electroweak gauge bosons in the Littlest Higgs Model

   J. I. Aranda🇲🇽 · I. Cortes-Maldonado🇲🇽 · S. Montejo-Montejo🇲🇽 · F. Ramirez-Zavaleta🇲🇽 · E. S. Tututi🇲🇽

   We study the heavy neutral scalar decays into standard model electroweak gauge bosons in the context of the Littlest Higgs model. We focus our attention on the ${\Phi }^0\to WW,\gamma V$ processes induced at the one-loop level, with $V=\gamma ,Z$. Since the branching ratios of the ${\Phi }^0\to \gamma V$ decays result very suppressed, only the ${\Phi }^0\to WW$ process is analyzed in the framework of possible experimental scenarios by using heavy scalar masses between 1.6 TeV until 3.3 TeV. The branching ratio for the ${\Phi }^0\to WW$ decay is of the order of $10^{-3}$ throughout the interval 2 TeV $<f<$ 4 TeV, which represent the global symmetry breaking scale of the theory. Thus, it is estimated the associated production cross section for the $pp\to {\Phi }^{0}X\to WW$, finding around ten events for $m_{{\Phi }^0}\approx 1.6$ TeV at best.

   hep-phJ.Phys.G(2017)·2 citations
8. 08*

   Topological deconfinement transition in QCD at finite isospin density

   Kouji Kashiwa🇯🇵 · Akira Ohnishi🇯🇵

   The confinement-deconfinement transition is discussed from topological viewpoints. The topological change of the system is achieved by introducing the dimensionless imaginary chemical potential ($\theta$). Then, the non-trivial free-energy degeneracy becomes the signal of the deconfinement transition and it can be visualized by using the map of the thermodynamic quantities to the circle $S^1$ along $\theta$. To understand this "topological" deconfinement transition at finite real quark chemical potential (${\mu }_{\mathrm{R}}$), we consider the isospin chemical potential (${\mu }_{\mathrm{iso}}$) in the effective model of QCD. The phase diagram at finite ${\mu }_{\mathrm{iso}}$ is identical with that at finite ${\mu }_{\mathrm{R}}$ outside of the pion-condensed phase at least in the large-$N_{\mathrm{c}}$ limit via the well-known orbifold equivalence. In the present effective model, the topological deconfinement transition does not show a significant dependence on ${\mu }_{\mathrm{iso}}$ and then we can expect that this tendency also appears at small ${\mu }_{\mathrm{R}}$. Also, the chiral transition and the topological deconfinement transition seems to be weakly correlated. If we will access lattice QCD data for the temperature dependence of the quark number density at finite ${\mu }_{\mathrm{iso}}$ with $\theta =\pi /3$, our surmise can be judged.

   hep-phhep-lathep-thPLB(2017)·25 citations
9. 09*

   Twenty years after the discovery of $\mu -\tau$ symmetry

   Takeshi Fukuyama🇯🇵

   It has passed 20 years after we proposed $\mu -\tau$ symmetry in light neutrino mass matrix. This model is simple but reproduced the characterestic properties of lepton sector. After that, during the experimental developments, there have appeared so many extensions but most of those phenomenological models are lacking systematic outlooks towards more fundamental theories. In this paper, we try to consider rather systematic model extensions and application to GUT model.

   hep-phPTEP(2017)·15 citations
10. 10*

    $g_{\mu }-2$ from Vector-Like Leptons in Warped Space

    Eugenio Megias🇪🇸 · Mariano Quiros🇪🇸 · Lindber Salas🇪🇸

    The experimental value of the anomalous magnetic moment of the muon, as well as the LHCb anomalies, point towards new physics coupled non-universally to muons and electrons. Working in extra dimensional theories, which solve the electroweak hierarchy problem with a warped metric, strongly deformed with respect to the AdS${}_5$ geometry at the infra-red brane, the LHCb anomalies can be solved by imposing that the bottom and the muon have a sizable amount of compositeness, while the electron is mainly elementary. Using this set-up as starting point we have proven that extra physics has to be introduced to describe the anomalous magnetic moment of the muon. We have proven that this job is done by a set of vector-like leptons, mixed with the physical muon through Yukawa interactions, and with a high degree of compositeness. The theory is consistent with all electroweak indirect, direct and theoretical constraints, the most sensitive ones being the modification of the $Z\bar{\mu }\mu$ coupling, oblique observables and constraints on the stability of the electroweak minimum. They impose lower bounds on the compositeness ($c\lesssim 0.37$) and on the mass of the lightest vector-like lepton ($\gtrsim 270$ GeV). Vector-like leptons could be easily produced in Drell-Yan processes at the LHC and detected at $\sqrt{s}=13$ TeV.

    hep-phhep-thJHEP(2017)·58 citations
11. 11*

    Dihadron production at the LHC: full next-to-leading BFKL calculation

    Francesco Giovanni Celiberto🇮🇹 · Dmitry Yu. Ivanov🇷🇺 · Beatrice Murdaca🇮🇹 · Alessandro Papa🇮🇹

    The study of the inclusive production of a pair of charged light hadrons (a "dihadron" system) featuring high transverse momenta and well separated in rapidity represents a clear channel for the test of the BFKL dynamics at the Large Hadron Collider (LHC). This process has much in common with the well known Mueller-Navelet jet production; however, hadrons can be detected at much smaller values of the transverse momentum than jets, thus allowing to explore an additional kinematic range, supplementary to the one studied with Mueller-Navelet jets. Furthermore, it makes it possible to constrain not only the parton densities (PDFs) for the initial proton, but also the parton fragmentation functions (FFs) describing the detected hadron in the final state. Here, we present the first full NLA BFKL analysis for cross sections and azimuthal angle correlations for dihadrons produced in the LHC kinematic ranges. We make use of the Brodsky-Lapage-Mackenzie (BLM) optimization method to set the values of the renormalization scale and study the effect of choosing different values for the factorization scale. We also gauge the uncertainty coming from the use of different PDF and FF parametrizations.

    hep-phEPJC(2017)·90 citations
12. 12*

    Two is not always better than one: Single Top Quarks and Dark Matter

    Deborah Pinna🇨🇭 · Alberto Zucchetta🇨🇭 · Matthew R. Buckley🇺🇸 · Florencia Canelli🇨🇭

    Dark matter interacting with the Standard Model fermions through new scalars or pseudoscalars with flavour-diagonal couplings proportional to fermion mass are well motivated theoretically, and provide a useful phenomenological model with which to interpret experimental results. Two modes of dark matter production from these models have been considered in the existing literature: pairs of dark matter produced through top quark loops with an associated monojet in the event, and pair production of dark matter with pairs of heavy flavoured quarks (tops or bottoms). In this paper, we demonstrate that a third, previously overlooked channel yields a non-negligible contribution to LHC dark matter searches in these models. In spite of a generally lower production cross section at LHC when compared to the associated top-pair channel, non-flavour violating single top quark processes are kinematically favored and can significantly increase the sensitivity to these models. Including dark matter production in association with a single top quark through scalar or pseudoscalar mediators, the exclusion limit set by the LHC searches for dark matter can be improved by $30$--$90\%$, depending on the mass assumed for the mediator particle.

    hep-phhep-exPRD(2017)·39 citations
13. 13*

    Quark Diagram Analysis of B-meson emitting vector (V) and vector (V) mesons

    Maninder Kaur🇮🇳

    This paper presents the two body weak nonleptonic decays of B-mesons emitting vector (V) and vector (V) mesons within the framework of the diagrammatic approaches at flavor SU(3) symmetry. We have investigated exclusive two body decays of B-meson using model independent quark diagram scheme. We have shown that the recent measurement of the two body exclusive decays of B-mesons can allow us to determine the magnitude and even sign of the QD amplitude for B VV decays. Therefore, we become able to make few predictions for their branching fractions.

    hep-phPhys.Part.Nucl.Lett.(2017)·1 citation
14. 14*

    Recent results on the meson and baryon spectrum from lattice QCD

    Daniel Mohler🇩🇪

    Recent lattice results on the meson and baryon spectrum with a focus on the determination of hadronic resonance masses and widths using a combined basis of single-hadron and hadron-hadron interpolating fields are reviewed. These mostly exploratory calculations differ from traditional lattice QCD spectrum calculations for states stable under QCD, where calculations with a full uncertainty estimate are already routinely performed. Progress and challenges in these calculations are highlighted.

    ↳ hep-lathep-phEPJ Web Conf.(2017)·7 citations
15. 15*

    Parametric estimate of the relative photon yields from the Glasma and the Quark-Gluon Plasma in heavy-ion collisions

    J. Berges🇩🇪 · K. Reygers🇩🇪 · N. Tanji🇩🇪 · R. Venugopalan🇺🇸

    Recent classical-statistical numerical simulations have established the "bottom-up" thermalization scenario of Baier et al. as the correct weak coupling effective theory for thermalization in ultrarelativistic heavy-ion collisions. We perform a parametric study of photon production in the various stages of this bottom-up framework to ascertain the relative contribution of the off-equilibrium "Glasma" relative to that of a thermalized Quark-Gluon Plasma. Taking into account the constraints imposed by the measured charged hadron multiplicities at RHIC and the LHC, we find that Glasma contributions are important especially for large values of the saturation scale at both energies. These non-equilibrium effects should therefore be taken into account in studies where weak coupling methods are employed to compute photon yields.

    ↳ nucl-thhep-phnucl-exPRC(2017)·72 citations
16. 16*

    Effect of pre-equilibrium phase on $R_{AA}$ and $v_2$ of heavy quarks in heavy ion collisions

    Santosh K. Das🇮🇹 · Marco Ruggieri🇨🇳 · Francesco Scardina🇮🇹 · Salvatore Plumari🇮🇹 · Vincenzo Greco🇮🇹

    Heavy quark $R_{AA}$ and $v_2$ have been calculated at RHIC energy considering initial conditions with and without pre-equilibrium phase to highlight the effect of the latter on heavy quark observables. The momentum evolution of the heavy quark has been studied by means of the Boltzmann transport equation. To model the pre-equilibrium phase we have used the KLN initial condition. We have found that the pre-equilibrium phase impacts the $R_{AA}$ of about 20-25 $\%$ whereas the impact on $v_2$ is very negligible. We have also calculated heavy quark $R_{AA}$ and $v_2$ in the case of initializations with early thermalized quark-gluon plasma. We have checked that the particular form of the initial spectrum is not very important for $R_{AA}$, the larger energy density being more important. In fact, comparing the results obtained within the two initializations we have found that one can mimic the impact of the pre-equilibrium phase using a early thermalized QGP medium.

    ↳ nucl-thhep-phJ.Phys.G(2017)·66 citations
17. 17*

    Prospects for beyond Standard Model Higgs boson searches at future LHC runs and other machines

    Krisztian Peters🇩🇪

    The discovery of the Higgs boson at the LHC opened up a new possibility to obtain a precise understanding of the origin of mass and the structure of the vacuum. Several theories beyond the Standard Model predict an extended Higgs sector, with additional scalar particles. We outline the complementary search possibilities for these beyond Standard Model Higgs bosons at the LHC and at possible future high-energy collider facilities.

    ↳ hep-exhep-phPoS(2017)·7 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.