Mon·Aug 28, 2017Monday·August 28, 2017

1. 01*

   Double, triple, and $n$-parton scatterings in high-energy proton and nuclear collisions

   David d'Enterria🇨🇭 · Alexander Snigirev🇷🇺

   The framework to compute the cross sections for the production of particles with high mass and/or large transverse momentum in double- (DPS), triple- (TPS), and in general $n$-parton scatterings, from the corresponding single-parton (${\sigma }_{\mathrm{SPS}}$) values in high-energy proton-proton, proton-nucleus, and nucleus-nucleus is reviewed. The basic parameter of the factorized $n$-parton scattering ansatz is an effective cross section ${\sigma }_{\mathrm{eff}}$ encoding all unknowns about the underlying generalized $n$-parton distribution in the proton (nucleon). In its simplest and most economical form, the ${\sigma }_{\mathrm{eff}}$ parameter can be derived from the transverse parton profile of the colliding protons and/or nucleus, using a Glauber approach. Numerical examples for the cross sections and yields expected for the concurrent DPS or TPS production of heavy-quarks, quarkonia, and/or gauge bosons in proton and nuclear collisions at LHC and Future Circular Collider (FCC) energies are provided. The obtained cross sections are based on perturbative QCD predictions for ${\sigma }_{\mathrm{SPS}}$ at next-to-leading-order (NLO) or next-to-NLO (NNLO) accuracy including, when needed, nuclear modifications of the corresponding parton densities.

   hep-phastro-ph.HEhep-exnucl-ex+1Adv.Ser.Direct.High Energy Phys.(2018)·56 citations
2. 02*

   The dark-matter axion mass

   Vincent B. Klaer🇩🇪 · Guy D. Moore🇩🇪

   We evaluate the efficiency of axion production from spatially random initial conditions in the axion field, so a network of axionic strings is present. For the first time, we perform numerical simulations which fully account for the large short-distance contributions to the axionic string tension, and the resulting dense network of high-tension axionic strings. We find nevertheless that the total axion production is somewhat less efficient than in the angle-averaged misalignment case. Combining our results with a recent determination of the hot QCD topological susceptibility (Borsanyi et al 2016), we find that if the axion makes up all of the dark matter, then the axion mass is m_a = 26.2 +-3.4 micro-electron volts.

   hep-phastro-ph.COhep-latJCAP(2017)·305 citations
3. 03*

   Anomalous gauge interactions in photon collisions at the LHC and the FCC

   Cristian Baldenegro🇺🇸 · Sylvain Fichet🇧🇷

   The forward proton detectors recently installed and operating at the LHC open the possibility to observe photon collisions with high precision, providing a novel window on physics beyond the Standard Model. We review recent simulations and theoretical developments about the measurement of anomalous $\gamma \gamma \gamma \gamma$ and $Z\gamma \gamma \gamma$ interactions. The searches for these anomalous gauge interactions are expected to set bounds on a wide range of particles including generic electroweak particles, neutral particles with dimension-5 coupling to gauge bosons, polarizable dark particles, and are typically complementary from new physics searches in other channels.

   hep-phCERN Proc.(2018)·5 citations
4. 04*

   Elastic scattering of a quark from a color field: longitudinal momentum exchange

   Jamal Jalilian-Marian🇺🇸

   Perturbative QCD in the small Bjorken $x$ limit can be formulated as an effective theory known as the Color Glass Condensate (CGC) formalism. The CGC formalism takes into account the dynamics of large gluon densities at small $x$ and has been successfully applied to Deep Inelastic Scattering (DIS) and particle production in high energy hadronic and nuclear collisions in the small $x$ kinematic region. The effective degrees of of freedom in CGC are Wilson lines which enter in the effective quark (and gluon) propagators and re-sum multiple soft scatterings from the small $x$ gluon field of the target. It is however known that the CGC effective theory breaks down when one probes the moderately large $x$ (high $p_t$) kinematics where collinear factorization and DGLAP evolution of parton distribution functions should be the right framework. Here we propose a general framework which may allow one to eventually unify the two approaches and to calculate pQCD cross sections in both small and large Bjorken $x$ regions. We take the first step towards this goal by deriving an expression for the quark propagator in a background field which includes scatterings from both small and large $x$ modes of the gluon field of the target. We describe how this quark propagator can be used to calculate QCD structure functions $F_2$ and $F_L$ at all $x$ and thus generalize the dipole model of DIS. We outline this approach can also be used to extend the so-called hybrid approach to particle production in the forward rapidity region of high energy hadronic and nuclear collisions to all $x$ and $p_t$ regions and speculate on how one may apply the same techniques to extend the McLerran-Venugopalan effective action used in high energy heavy ion collisions to include high $p_t$ physics.

   hep-phnucl-exnucl-thPRD(2017)·48 citations
5. 05*

   Energy density and path-length dependence of the fractional momentum loss in heavy-ion collisions at $\sqrt{s_{\mathrm{NN}}}$ from 62.4 to 5020 GeV

   Antonio Ortiz🇲🇽 · Omar Vázquez🇲🇽

   In this work a study of the fractional momentum loss ($S_{\mathrm{loss}}$) as a function of the characteristic path-length ($L$) and the Bjorken energy density times the equilibration time (${ϵ}_{\mathrm{Bj}}{\tau }_0$) for heavy-ion collisions at different $\sqrt{s_{\mathrm{NN}}}$ is presented. The study has been conducted using inclusive charged particles from intermediate to large transverse momentum ($5<p_{\mathrm{T}}<20$ GeV/$c$). Within uncertainties and for all the transverse momentum values which were explored, the fractional momentum loss linearly increases with $({ϵ}_{\mathrm{Bj}}{\tau }_0{)}^{3/8}$$L$. The functional form of $S_{\mathrm{loss}}$ vs. $({ϵ}_{\mathrm{Bj}}{\tau }_0{)}^{3/8}$$L$ seems to be universal. Moreover, for identified charged hadrons a linear relationship between $S_{\mathrm{loss}}$ and $L$ is also observed. The behaviour of data could provide important information aimed to understand the parton energy loss mechanism in heavy-ion collisions and some insight into the expected effect for small systems.

   hep-phPRC(2018)·11 citations
6. 06*

   SUSY Global Fits

   Peter Athron (on behalf of the GAMBIT collaboration)🇦🇺

   We present comprehensive global fits of supersymmetric (SUSY) models from the Global and Modular Beyond-the-Standard-Model Inference Tool (GAMBIT) collaboration, based on arXiv:1705.07935 and arXiv:1705.07917. We investigate several variants of the minimal supersymmetric standard model, a fully constrained version (CMSSM) with universal scalar ($m_0$), gaugino ($m_{1/2}$) and trilinear masses ($A_0$) at the gauge coupling unification scale, a similar model that is relaxed by adding an extra parameter for the soft Higgs masses (NUHM1), another where the soft Higgs masses are also split (NUHM2) and finally a weak scale MSSM7 model. We use the public GAMBIT global fitting framework and take into account all relevant data to reveal the regions of parameter space with the highest likelihood. Our results reveal that all models have very heavy scenarios that are well out of reach of the LHC, but will be probed by forthcoming dark matter experiments, as well as a stop-co-annihilation region which has better prospects for detection in collider experiments. The stau co-annihilation region is excluded from the CMSSM at $2\sigma$ but is present in the NUHM1 and NUHM2 variants. Finally by relaxing constraints in the NUHM1, NUHM2 and MSSM7 we see additional regions appear: lighter chargino co-annihilation region, sbottom co-annihilation and $h/Z$ funnels.

   hep-ph2 citations
7. 07*

   Measuring the mass, width, and couplings of semi-invisible resonances with the Matrix Element Method

   Amalia Betancur🇨🇴 · Dipsikha Debnath🇺🇸 · James S. Gainer🇺🇸 · Konstantin T. Matchev🇺🇸 · Prasanth Shyamsundar🇺🇸

   We demonstrate the use of the Matrix Element Method (MEM) for the measurement of masses, widths, and couplings in the case of single or pair production of semi-invisibly decaying resonances. For definiteness, we consider the two-body decay of a generic resonance to a visible particle from the Standard Model (SM) and a massive invisible particle. It is well known that the mass difference can be extracted from the endpoint of a transverse kinematic variable like the transverse mass, $M_T$, or the Cambridge $M_{T2}$ variable, but measuring the overall mass scale is a very difficult problem. We show that the MEM can be used to obtain not only the absolute mass scale, but also the width of the resonance and the tensor structure of its couplings. Apart from new physics searches, our results can be readily applied to the case of SM $W$ boson production at the CERN Large Hadron Collider (LHC), where one can repeat the measurements of the $W$ properties in a general and model-independent framework.

   hep-phhep-exPRD(2019)·8 citations
8. 08*

   $B^{\ast }$ $\to$ $\bar{D}D$ decays with perturbative QCD approach

   Junfeng Sun🇨🇳 · Haiyan Li🇨🇳 · Yueling Yang🇨🇳 · Na Wang🇨🇳 · Qin Chang🇨🇳 · Gongru Lu🇨🇳

   The nonleptonic two-body $B^{\ast }$ $\to$ $\bar{D}D$ weak decays are studied phenomenologically with the perturbative QCD factorization approach. It is found that the $B_s^{\ast 0}$ $\to$ $D_s^{-}{D}_s^{+}$, $B_d^{\ast 0}$ $\to$ $D_d^{-}{D}_s^{+}$, and $B_u^{\ast +}$ $\to$ ${\bar{D}}_u^0{D}_s^{+}$ decays have branching ratios $\gtrsim$ $10^{-9}$, and might be promisingly measurable at the running LHC and forthcoming SuperKEKB experiments in the future.

   hep-phJ.Phys.G(2017)·3 citations
9. 09*

   Study of the ${\bar{B}}_q^{\ast }$ $\to$ $DM$ decays with perturbative QCD approach

   Junfeng Sun🇨🇳 · Jie Gao🇨🇳 · Yueling Yang🇨🇳 · Qin Chang🇨🇳 · Na Wang🇨🇳 · Gongru Lu🇨🇳 · Jinshu Huang🇨🇳

   The ${\bar{B}}_q^{\ast }$ $\to$ $DP$, $DV$ weak decays are studied with the perturbative QCD approach, where $q$ $=$ $u$, $d$ and $s$; $P$ and $V$ denote the ground $SU(3)$ pseudoscalar and vector meson nonet. It is found that the branching ratios for the color-allowed ${\bar{B}}_q^{\ast }$ $\to$ $D_q{\rho }^{-}$ decays can reach up to $10^{-9}$ or more, and should be promisingly measurable at the running LHC and forthcoming SuperKEKB experiments in the near future.

   hep-phPRD(2017)·2 citations
10. 10*

    Exotic glueball $0^{\pm -}$ states in QCD Sum Rules

    Alexandr Pimikov🇨🇳 · Hee-Jung Lee🇰🇷 · Nikolai Kochelev🇷🇺 · Pengming Zhang🇨🇳 · Viachaslau Khandramai🇧🇾

    The lowest dimension three-gluon currents that couple to the exotic $0^{\pm -}$ glueballs have been constructed using the helicity formalism. Based on the constructed currents, we obtain new QCD SRs that have been used to extract the masses and the decay constants of the scalar exotic $0^{\pm -}$ glueballs. We estimate the masses for the scalar state and for the pseudoscalar state to be $m_{+}=9.8_{-1.4}^{+1.3}$ GeV and $m_{-}=6.8_{-1.2}^{+1.1}$ GeV.

    hep-phPRD(2017)·27 citations
11. 11*

    Single- and double-scattering production of four muons in ultraperipheral PbPb collisions at the Large Hadron Collider

    Andreas van Hameren🇵🇱 · Mariola Klusek-Gawenda🇵🇱 · Antoni Szczurek🇵🇱

    We discuss production of two ${\mu }^{+}{\mu }^{-}$ pairs in ultraperipheral ultrarelativistic heavy ion collisions at the LHC. We take into account electromagnetic (two-photon) double-scattering production and for a first time direct $\gamma \gamma$ production of four muons in one scattering. We study the unexplored process $\gamma \gamma \to {\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$. We present predictions for total and differential cross sections. Measurable nuclear cross sections are obtained and corresponding differential distributions and counting rates are presented.

    hep-phhep-exnucl-thPLB(2018)·23 citations
12. 12*

    Analyticity Constraints for Hadron Amplitudes: Going High to Heal Low Energy Issues

    JPAC Collaboration: V. Mathieu🇺🇸 · J. Nys🇧🇪 · A. Pilloni🇺🇸 · C. Fernández-Ramírez🇲🇽 · A. Jackura🇺🇸 · M. Mikhasenko🇩🇪 · V. Pauk🇺🇸 · A. P. Szczepaniak🇺🇸 · G. Fox🇺🇸

    Analyticity constitutes a rigid constraint on hadron scattering amplitudes. This property is used to relate models in different energy regimes. Using meson photoproduction as a benchmark, we show how to test contemporary low energy models directly against high energy data. This method pinpoints deficiencies of the models and treads a path to further improvement. The implementation of this technique enables one to produce more stable and reliable partial waves for future use in hadron spectroscopy and new physics searches.

    hep-phEPL(2018)·10 citations
13. 13*

    Effective-field theory analysis of the ${\tau }^{-}\to {\eta }^{(\prime )}{\pi }^{-}{\nu }_{\tau }$ decays

    E. A. Garcés🇲🇽 · M. Hernández Villanueva🇲🇽 · G. López Castro🇲🇽 · P. Roig🇲🇽

    The rare ${\tau }^{-}\to {\eta }^{(\prime )}{\pi }^{-}{\nu }_{\tau }$ decays, which are suppressed by $G$-parity in the Standard Model (SM), can be sensitive to the effects of new interactions. We study the sensitivity of different observables of these decays in the framework of an effective field theory that includes the most general interactions between SM fields up to dimension six, assuming massless neutrinos. Owing to the strong suppression of the SM isospin breaking amplitudes, we find that the different observables would allow to set constraints on scalar interactions that are stronger than those coming from other low-energy observables.

    hep-phJHEP(2017)·64 citations
14. 14*

    Diboson Interference Resurrection

    Giuliano Panico🇪🇸 · Francesco Riva🇨🇭 · Andrea Wulzer🇨🇭

    High-energy diboson processes at the LHC are potentially powerful indirect probes of heavy new physics, whose effects can be encapsulated in higher-dimensional operators or in modified Standard Model couplings. An obstruction however comes from the fact that leading new physics effects often emerge in diboson helicity amplitudes that are anomalously small in the Standard Model. As such, the formally leading Standard Model/New Physics interference contribution cancels in inclusive measurements. This paper describes a solution to this problem.

    hep-phhep-exPLB(2018)·124 citations
15. 15*

    Bayesian naturalness, simplicity, and testability applied to the $B-L$ MSSM GUT

    Panashe Fundira🇺🇸 · Austin Purves🇺🇸

    Recent years have seen increased use of Bayesian model comparison to quantify notions such as naturalness, simplicity, and testability, especially in the area of supersymmetric model building. After demonstrating that Bayesian model comparison can resolve a paradox that has been raised in the literature concerning the naturalness of the proton mass, we apply Bayesian model comparison to GUTs, an area to which it has not been applied before. We find that the GUTs are substantially favored over the non-unifying puzzle model. Of the GUTs we consider, the $B-L$ MSSM GUT is the most favored, but the MSSM GUT is almost equally favored.

    hep-phhep-thInt.J.Mod.Phys.A(2018)·13 citations
16. 16*

    Impact of Beyond the Standard Model Physics in the Detection of the Cosmic Neutrino Background

    Martín Arteaga🇧🇷 · Enrico Bertuzzo🇧🇷 · Yuber F. Perez-Gonzalez🇧🇷 · Renata Zukanovich Funchal🇧🇷

    We discuss the effect of Beyond the Standard Model charged current interactions on the detection of the Cosmic Neutrino Background by neutrino capture on tritium in a PTOLEMY-like detector. We show that the total capture rate can be substantially modified for Dirac neutrinos if scalar or tensor right-chiral currents, with strength consistent with current experimental bounds, are at play. We find that the total capture rate for Dirac neutrinos, ${\Gamma }_{\mathrm{D}}^{\mathrm{BSM}}$, can be between 0.3 to 2.2 of what is expected for Dirac neutrinos in the Standard Model, ${\Gamma }_{\mathrm{D}}^{\mathrm{SM}}$, so that it can be made as large as the rate expected for Majorana neutrinos with only Standard Model interactions. A non-negligible primordial abundance of right-handed neutrinos can only worsen the situation, increasing ${\Gamma }_{\mathrm{D}}^{\mathrm{BSM}}$ by 30 to 90\%. On the other hand, if a much lower total rate is measured than what is expected for ${\Gamma }_{\mathrm{D}}^{\mathrm{SM}}$, it may be a sign of new physics.

    hep-phastro-ph.COJHEP(2017)·15 citations
17. 17*

    Oblique Confinement at $\theta \ne 0$ in weakly coupled gauge theories with deformations

    Mohamed M. Anber🇺🇸 · Ariel R. Zhitnitsky🇨🇦

    The main focus of this work is to test the ideas related to the oblique confinement in a theoretically controllable manner using the "deformed QCD" as a toy model. We explicitly show that the oblique confinement in the weakly coupled gauge theories emerges as a result of condensation of $N$ types of monopoles shifted by the phase $\exp (i\frac{\theta +2\pi m}{N})$ in Bloch type construction. It should be contrasted with conventional and commonly accepted viewpoint that the confinement at $\theta \ne 0$ is due to the condensation of the electrically charged dyons which indeed normally emerge in the systems with $\theta \ne 0$ as a result of Witten's effect. We explain the basic reason why the "dyon" mechanism does not materialize-- it is because the Witten's effect holds for a static magnetic monopole treated as an external source. It should be contrasted with our case when $N$- types of monopoles are not static, but rather the dynamical degrees of freedom which fluctuate and themselves determine the ground state of the system.

    ↳ hep-thhep-lathep-phPRD(2017)·19 citations
18. 18*

    Three Photon Entanglement from Ortho-Positronium Revisited

    Marek Nowakowski🇨🇴 · Diego Bedoya Fierro🇨🇴

    Entanglement of three photons from the decay of ortho-positronium is re-analyzed. We use the full three body phase space to write down the entangled states classified according to the spin directions of the ortho-positronium. Even in the case when the spin is perpendicular to the decay plane, we find non-negligible phases entering the entangled state. This has not been noticed before. We advocate a fixed quantization axis of the spin for the sake of generality. A brief discussion of a three dimensional formalism for photons, including correlations, versus a two dimensional one is given.

    ↳ quant-phhep-phActa Phys.Polon.B(2017)·24 citations
19. 19*

    $\eta$-nucleus interaction from the $d+d$ reaction around the $\eta$ production threshold

    N. Ikeno🇯🇵 · H. Nagahiro🇯🇵 · D. Jido🇯🇵 · S. Hirenzaki🇯🇵

    The $\eta$ mesic nucleus is considered to be one of the interesting exotic many body systems and has been studied since 1980's theoretically and experimentally. Recently, the formation of the $\eta$ mesic nucleus in the fusion reactions of the light nuclei such as $d+d\to (\eta +\alpha )\to X$ has been proposed and the experiments have been performed by WASA-at-COSY. We develop a theoretical model to evaluate the formation rate of the $\eta$ mesic nucleus in the fusion reactions and show the calculated results. We find that the $\eta$ bound states could be observed in the reactions in cases with the strong attractive and small absorptive $\eta$-nucleus interactions. We compare our results with existing data of the $d+d\to \eta +\alpha$ and the $d+d\to {}^3\mathrm{He}+N+\pi$ reactions. We find that the analyses by our theoretical model with the existing data can provide new information on the $\eta$-nucleus interaction.

    ↳ nucl-thhep-phnucl-exEPJA(2017)·23 citations
20. 20*

    The Local Dark Matter Density from SDSS-SEGUE G-dwarfs

    Sofia Sivertsson🇸🇪 · Hamish Silverwood🇪🇸 · Justin I. Read🇬🇧 · Gianfranco Bertone🇳🇱 · Pascal Steger🇨🇭

    We derive the local dark matter density by applying the integrated Jeans equation method from Silverwood et al. (2016) to SDSS-SEGUE G-dwarf data processed and presented by Büdenbender et al. (2015). We use the MultiNest Bayesian nested sampling software to fit a model for the baryon distribution, dark matter and tracer stars, including a model for the 'tilt term' that couples the vertical and radial motions, to the data. The $\alpha$-young population from Büdenbender et al. (2015) yields the most reliable result of ${\rho }_{\mathrm{DM}}=0.46_{-0.09}^{+0.07}{\mathrm{GeV}\mathrm{cm}}^{-3}=0.012_{-0.002}^{+0.001}{\mathrm{M}}_{\odot }{\mathrm{pc}}^{-3}$. Our analyses yield inconsistent results for the $\alpha$-young and $\alpha$-old data, pointing to problems in the tilt term and its modelling, the data itself, the assumption of a flat rotation curve, or the effects of disequilibria.

    ↳ astro-ph.GAhep-phMNRAS(2018)·123 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.