HEP Phenomenology·hep-ph

Fri·Jan 5, 2018Friday·January 5, 2018

13 papers—6 primary·7 cross-listed·reconstructed*

01*
A remark on the sign change of the four-particle azimuthal cumulant in small systems
Adam Bzdak🇵🇱 · Guo-Liang Ma🇨🇳
The azimuthal cumulants, $c_{2} {2}$ and $c_{2} {4}$ , originating from the global conservation of transverse momentum in the presence of hydro-like elliptic flow are calculated. We observe the sign change of $c_{2} {4}$ for small number of produced particles. This is in a qualitative agreement with the recent ATLAS measurement of multi-particle azimuthal correlations with the subevent cumulant method.
hep-phhep-exnucl-exnucl-thPLB(2018)·10 citations
02*
Goldstone Modes in Renormalizable Supersymmetric SO(10) Model
Xian-Zheng Bai🇨🇳 · Da-Xin Zhang🇨🇳
We solve the Goldstone modes in the renormalizable SUSY SO(10) model with general couplings. The Goldstones are expressed by the Vacuum Expectation Values and the Clebsch-Gordan coefficients of relevant symmetries without explicit dependence on the parameters of the model.
hep-phEPJC(2018)·0 citations
03*
Reanalysis of the Higgs-boson decay $H \to g g$ up to $α_{s}^{6}$ -order level using the principle of maximum conformality
Jun Zeng🇨🇳 · Xing-Gang Wu🇨🇳 · Shi Bu🇨🇳 · Jian-Ming Shen🇨🇳 · Sheng-Quan Wang🇨🇳
Using the newly available $α_{s}^{6}$ -order QCD correction to the Higgs decay channel $H \to g g$ , we make a detailed discussion on the perturbative properties of the decay width $Γ (H \to g g)$ by using the principle of maximum conformality (PMC). The PMC provides a way to eliminate the conventional renormalization scheme-and-scale ambiguities, which uses the renormalization group equation to determine the optimal running behavior of the strong coupling constant at each order via a recursive way. Even though there is no ambiguity for setting the renormalization scale, there is residual scale dependence for the PMC predictions due to unknown high-order terms. Using the $α_{s}^{6}$ -order terms, the somewhat larger residual renormalization scale dependence at the $α_{s}^{5}$ -order level observed in our previous work can be greatly suppressed, which shows $Γ (H \to g g) ∣_{PMC} = 337.9 \pm 1. 7_{- 0.1}^{+ 0.9} \pm 1.9$ KeV, where the first error is caused by the Higgs mass uncertainty $Δ M_{H} = 0.24$ GeV, the second one is the residual scale dependence by varying the initial choice of scale within the region of $[M_{H} / 2, 4 M_{H}]$ , and the third one is the conservative prediction of unknown high-order contributions.
hep-phJ.Phys.G(2018)·11 citations
04*
Magnetic moment of the rho meson in instant-form relativistic quantum mechanics
A.F. Krutov🇷🇺 · R.G. Polezhaev🇷🇺 · V.E. Troitsky🇷🇺
We derive an explicit analytical expression for the magnetic dipole moment of the rho meson, mu_rho, in a relativistic constituent-quark model. We adopt our relativistic approach to composite systems, modified instant-form (mIF) Relativistic Quantum Mechanics (RQM), that we used particularly to construct a unified pi&rho model (Phys. Rev. D93, 036007 (2016) = arXiv:1602.00907) describing electroweak properties of light mesons. This model provides a parameter-free calculation to give mu_rho=(2.16+-0.03) [e/2M_rho] which is in accordance with the conventional experimental data. The magnetic, quadrupole and charge form factors also are derived and presented. We consider the small uncertainty of our value of magnetic moment as one of undoubted advantages of the method. A comparison is made with recent lattice QCD results and previous calculations using a variety of methods.
hep-phPRD(2018)·26 citations
05*
$N^{*}$ Form Factors based on a Covariant Quark Model
G. Ramalho🇧🇷
We discuss the results of the covariant spectator quark model for the several $γ^{*} N \to N^{*}$ transitions, where $N$ is the nucleon and $N^{*}$ a nucleon excitation. More specifically, we present predictions for the form factors and transition amplitudes associated with the resonances $N (1440) 1/ 2^{+}$ , $N (1535) 1/ 2^{-}$ , $N (1520) 3/ 2^{-}$ , $Δ (1620) 1/ 2^{-}$ and $N (1650) 1/ 2^{-}$ . The estimates based on valence quark degrees of freedom are compared with the available data, particularly with the recent Jefferson Lab data at low and large momentum transfer ( $Q^{2}$ ). In general, the estimates are in good agreement with the empirical data for $Q^{2} > 2$ GeV $^{2}$ , with a few exceptions. The results are discussed in terms of the role of the valence quarks and the meson cloud excitations for the different resonances $N^{*}$ . We also review our results for the resonance $Δ (1232) 3/ 2^{+}$ and discuss the relevance of the pion cloud component for the magnetic dipole form factor and the electric and Coulomb quadrupole form factors.
hep-phhep-exhep-latnucl-ex+1Few Body Syst.(2018)·26 citations
06*
Matching factorization theorems with an inverse-error weighting
Miguel G. Echevarria🇮🇹 · Tomas Kasemets🇩🇪 · Jean-Philippe Lansberg🇫🇷 · Cristian Pisano🇮🇹 · Andrea Signori🇺🇸
We propose a new fast method to match factorization theorems applicable in different kinematical regions, such as the transverse-momentum-dependent and the collinear factorization theorems in Quantum Chromodynamics. At variance with well-known approaches relying on their simple addition and subsequent subtraction of double-counted contributions, ours simply builds on their weighting using the theory uncertainties deduced from the factorization theorems themselves. This allows us to estimate the unknown complete matched cross section from an inverse-error-weighted average. The method is simple and provides an evaluation of the theoretical uncertainty of the matched cross section associated with the uncertainties from the power corrections to the factorization theorems (additional uncertainties, such as the nonperturbative ones, should be added for a proper comparison with experimental data). Its usage is illustrated with several basic examples, such as $Z$ boson, $W$ boson, $H^{0}$ boson and Drell-Yan lepton-pair production in hadronic collisions, and compared to the state-of-the-art Collins-Soper-Sterman subtraction scheme. It is also not limited to the transverse-momentum spectrum, and can straightforwardly be extended to match any (un)polarized cross section differential in other variables, including multi-differential measurements.
hep-phPLB(2018)·44 citations
07*
Induced Bremsstrahlung by light in graphene
Cristian Villavicencio🇨🇱 · Alfredo Raya🇲🇽
We study the generation of an electromagnetic current in monolayer graphene immersed in a weak perpendicular magnetic field and radiated with linearly polarized monochromatic light. Such a current emits Bremsstrahlung radiation with the same amplitude above and below the plane of the sample, in the latter case consistent with the small amount of light absorption in the material. This mechanism could be an important contribution for the reflexion of light phenomenon in graphene.
↳ cond-mat.mes-hallcond-mat.str-elhep-phRevista Mexicana de F\'isica 64, 132 (201…·0 citations
08*
Nucleon Effective Masses in Neutron-Rich Matter
Bao-An Li🇺🇸 · Bao-Jun Cai🇨🇳 · Lie-Wen Chen🇨🇳 · Jun Xu🇨🇳
Various kinds of isovector nucleon effective masses are used in the literature to characterize the momentum/energy dependence of the nucleon symmetry potential or self-energy due to the space/time non-locality of the underlying isovector strong interaction in neutron-rich nucleonic matter. The multifaceted studies on nucleon isovector effective masses are multi-disciplinary in nature. Besides structures, masses and low-lying excited states of nuclei as well as nuclear reactions, studies of the isospin dependence of short-range correlations in nuclei from scatterings of high-energy electrons and protons on heavy nuclei also help understand nucleon effective masses especially the so-called E-mass in neutron-rich matter. A thorough understanding of all kinds of nucleon effective masses has multiple impacts on many interesting issues in both nuclear physics and astrophysics. We review some of the significant progresses made in recent years by the nuclear physics community in resolving some of the hotly debated and longstanding issues regarding nucleon effective masses especially in dense neutron-rich matter.
↳ nucl-thastro-ph.HEhep-exhep-ph+1PPNP(2018)·221 citations
09*
Dynamical constraints on a dark matter spike at the Galactic Centre from stellar orbits
Thomas Lacroix🇫🇷
In this work I use astrometric and spectroscopic data on the S2 star at the Galactic Centre (GC) up to 2016 to derive specific constraints on the size of a dark matter (DM) spike around the central supermassive black hole Sgr A*. These limits are the best direct constraints on a DM spike at the GC for non-annihilating DM and exclude a spike with radius greater than a few tens of parsecs for cuspy outer halos and a few hundred parsecs for cored outer halos.
↳ astro-ph.GAastro-ph.COhep-phAstron.Astrophys.(2018)·110 citations
10*
Constraining the mass of dark photons and axion-like particles through black-hole superradiance
Vitor Cardoso🇵🇹 · Óscar J. C. Dias🇬🇧 · Gavin S. Hartnett🇬🇧 · Matthew Middleton🇬🇧 · Paolo Pani🇮🇹 · Jorge E. Santos🇬🇧
Ultralight bosons and axion-like particles appear naturally in different scenarios and could solve some long-standing puzzles. Their detection is challenging, and all direct methods hinge on unknown couplings to the Standard Model of particle physics. However, the universal coupling to gravity provides model-independent signatures for these fields. We explore here the superradiant instability of spinning black holes triggered in the presence of such fields. The instability taps angular momentum from and limits the maximum spin of astrophysical black holes. We compute, for the first time, the spectrum of the most unstable modes of a massive vector (Proca) field for generic black-hole spin and Proca mass. The observed stability of the inner disk of stellar-mass black holes can be used to derive \emph{direct} constraints on the mass of dark photons in the mass range $1 0^{- 13} eV ≲ m_{V} ≲ 3 \times 1 0^{- 12} eV$ . By including also higher azimuthal modes, similar constraints apply to axion-like particles in the mass range $6 \times 1 0^{- 13} eV ≲ m_{ALP} ≲ 1 0^{- 11} eV$ . Likewise, mass and spin distributions of supermassive BHs --~as measured through continuum fitting, K $α$ iron line, or with the future space-based gravitational-wave detector LISA~-- imply indirect bounds in the mass range approximately $1 0^{- 19} eV ≲ m_{V}, m_{ALP} ≲ 1 0^{- 13} eV$ , for both axion-like particles and dark photons. Overall, superradiance allows to explore a region of approximately $8$ orders of magnitude in the mass of ultralight bosons.
↳ gr-qcastro-ph.HEhep-phJCAP(2018)·309 citations
11*
First measurement of transverse-spin-dependent azimuthal asymmetries in the Drell-Yan process
Bakur Parsamyan🇨🇭
The COMPASS experiment at CERN, as part of its programme addresses the exploration of the transverse spin structure of the nucleon by measuring spin (in)dependent azimuthal asymmetries in semi-inclusive DIS and, recently, also in Drell-Yan processes. Between 2002 and 2010 COMPASS performed a series of SIDIS measurements, using a longitudinally polarized muon beam impinging on transversely polarized $^{6} L i D$ or $N H_{3}$ targets. Drell-Yan measurements with a $π^{-}$ beam interacting with a transversely polarized $N H_{3}$ target started with the 2015 run and will be continued in 2018. In this Letter the first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan process is reported. Measured asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3~\gvcw\, and 8.5~\gvcw. A recent COMPASS SIDIS measurement was obtained at a hard scale comparable to that of these DY results. This provides a unique possibility to test predicted in QCD sign change of the Sivers TMD PDF and other (pseudo-)universal features of transvers momentum dependent parton distribution functions.
↳ hep-exhep-phPoS(2018)·3 citations
12*
Measurement of longitudinal-target-polarization dependent azimuthal asymmetries in SIDIS at COMPASS experiment
Bakur Parsamyan🇨🇭
Preliminary results obtained by the COMPASS experiment for longitudinal-spin-dependent azimuthal asymmetries in single-hadron muoproduction off protons are presented for the first time. The analysis was carried out on the full data sample collected by COMPASS with longitudinally polarized proton ( $N H_{3}$ ) target in 2007 and 2011 using 160~\gvc and 200~\gvc muon beams, correspondingly. Within QCD parton model approach extracted asymmetries are giving access to the specific convolutions of certain transverse-momentum-dependent \textit{twist-2} and \textit{higher twist} parton distribution functions and fragmentation functions. In order to access different features of the involved distributions, the asymmetries are extracted as functions of different kinematic variables for both positive and negative single-hadron productions. The significant amount of collected data and wide kinematic range give unique importance to the results. Obtained asymmetries are compared with previous measurements performed by HERMES experiment and with available model predictions.
↳ hep-exhep-phPoS(2018)·13 citations
13*
Solar Flares and the Axion Quark Nugget Dark Matter Model
Ariel Zhitnitsky🇨🇦
We advocate the idea that the nanoflares conjectured by Parker long ago to resolve the corona heating problem, may also trigger the larger solar flares. The arguments are based on the model where emission of extreme ultra violet (EUV) radiation and soft x-rays from the Sun are powered externally by incident dark matter particles within the Axion Quark Nugget (AQN) Dark Matter Model. The corresponding annihilation events of the AQNs with the solar material are identified with nanoflares. This model was originally invented as a natural explanation of the observed ratio $Ω_{dark} \sim Ω_{visible}$ when the DM and visible matter densities assume the same order of magnitude values. This model gives a very reasonable intensity of EUV radiation without adjustments of any parameters in the model. When the same nuggets enter the regions with high magnetic field they serve as the triggers igniting the magnetic reconnections which eventually may lead to much larger flares. Technically, the magnetic reconnection is ignited due to the shock wave which inevitably develops when the dark matter nuggets enter the solar atmosphere with velocity $v_{AQN} \sim 600 km/s$ which is much higher than the speed of sound $c_{s}$ , such that the Mach number $M = v_{AQN} / c_{s} ≫ 1$ . These shock waves generate very strong and very short impulses expressed in terms of pressure $Δ p / p \sim M^{2}$ and temperature $Δ T / T \sim M^{2}$ in vicinity of (would be) magnetic reconnection area. The mechanism is consistent with the observed scaling of the flare distribution $d N \sim W^{- α} d W$ as a function of the flare's energy $W$ . We also speculate that the same nuggets may trigger the sunquakes which are known to be correlated with large flares.
↳ astro-ph.SRastro-ph.COastro-ph.HEhep-ph+1Phys.Dark Univ.(2018)·34 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.