HEP Phenomenology·hep-ph

Tue·Jul 4, 2017Tuesday·July 4, 2017

27 papers—22 primary·5 cross-listed·reconstructed*

01*
Efficient Monte Carlo Integration Using Boosted Decision Trees and Generative Deep Neural Networks
Joshua Bendavid🇺🇸
New machine learning based algorithms have been developed and tested for Monte Carlo integration based on generative Boosted Decision Trees and Deep Neural Networks. Both of these algorithms exhibit substantial improvements compared to existing algorithms for non-factorizable integrands in terms of the achievable integration precision for a given number of target function evaluations. Large scale Monte Carlo generation of complex collider physics processes with improved efficiency can be achieved by implementing these algorithms into commonly used matrix element Monte Carlo generators once their robustness is demonstrated and performance validated for the relevant classes of matrix elements.
hep-phphysics.comp-ph85 citations
02*
NMSSM Light Decoupled Higgs Singlet at CEPC
C.T. Potter🇺🇸
We describe the phenomenology of light singlet Higgs bosons in the Next-to-Minimal Supersymmetry Model (NMSSM) which are mostly decoupled from the rest of Supersymmetry. Noting that the Large Hadron Collider has not excluded this scenario, we describe previous searches for light Higgs bosons at the Large Electron Positron collider and evaluate the sensitivity to neutralino production and decay to light singlet Higgs bosons at the proposed $s = 250$ ~GeV Circular Electron Positron Collider.
hep-phInt.J.Mod.Phys.A(2017)·1 citation
03*
Resonance Production of Excited u-quark at the FCC Based $γ$ $p$ Colliders
Yusuf Oguzhan Günaydın (1)🇹🇷 · Mehmet Sahin (2)🇹🇷 · Saleh Sultansoy (3) ((1) KSÜ, (2) Usak U., (3) TOBB ETU)🇹🇷
Several Beyond the Standard Model theories are proposed that fermions might have composite substructure. The existence of excited quarks is going to be the noticeable proof for the compositeness of Standard Model fermions. For this reason, excited quarks have been investigated by phenomenological and experimental high energy physicists at various collider options for the last few decades. The Future Circular Collider (FCC) has been recently planned as particle accelerator to be established at CERN. Beside the $s$ = 100 TeV proton-proton collisions, the FCC includes electron-positron and electron-proton collision options. Construction of linear $e^{-} e^{+}$ colliders (or dedicated e-linac) tangential to the FCC will afford an opportunity to handle multi-TeV $e p$ and $γ p$ collisions. In this respect, we executed a simulation of the resonance production of the excited $u$ quark at the FCC based $γ p$ colliders with choosing both the polarized and unpolarized photon beams. The findings revealed that the chirality structure of the $q^{*}$ - $q$ - $γ$ vertex can be determined by the photon beam polarization. The attainable mass limits of the excited $u$ quark reached the highest values when the polarized photon beam was chosen. In addition, the ultimate compositeness scale values can be handled by appropriate choice of the photon beam polarization.
hep-phhep-exActa Phys.Polon.B(2018)·6 citations
04*
Probing the hot and dense nuclear matter with $K^{*}, K ˉ^{*}$ vector mesons
Andrej Ilner🇩🇪 · Justin Blair🇺🇸 · Daniel Cabrera🇪🇸 · Christina Markert🇺🇸 · Elena Bratkovskaya🇩🇪
We investigate probing the hot and dense nuclear matter with strange vector mesons ( $K^{*}, K ˉ^{*}$ ). Our analysis is based on PHSD which incorporates partonic and hadronic dof and describes the full dynamics of HICs. This allows to study the $K^{*}$ and $K ˉ^{*}$ meson formation from the QGP and the in-medium effects related to the modification of their properties during the propagation in dense and hot matter. We employ relativistic Breit-Wigner spectral functions for the $K^{*}, K ˉ^{*}$ mesons with self-energies obtained from a G-matrix approach to study the role of in-medium effects on the $K^{*}$ and $K ˉ^{*}$ meson dynamics in HIC from FAIR/NICA to LHC energies. According to our analysis most of the final $K^{*} / K ˉ^{*}$ s, that can be observed experimentally, are produced during the late hadronic phase and stem dominantly from the $K (K ˉ) + π \to K^{*} (K ˉ^{*})$ formation channel. The amount of $K^{*} / K ˉ^{*}$ s originating from the QGP channel is comparatively small even at LHC energies and such $K^{*} / K ˉ^{*}$ s can hardly be reconstructed experimentally due to the rescattering of final pions and (anti-)kaons. This mirrors the results from our previous study on the strange vector-meson production in HICs at RHIC energies. The influence of the in-medium effects on the dynamics of the $K^{*} / K ˉ^{*}$ is rather small since they are mostly produced at low baryon densities. Additional cuts on the shape of the observed signal and the range of the invariant mass region of the $K^{*} / K ˉ^{*}$ also affect the final spectra. We demonstrate that the $K^{*} / K ˉ^{*}$ in-medium effects are more visible at lower beam energy, e.g. FAIR/NICA and BES RHIC energies, where the production of $K^{*} / K ˉ^{*}$ s occurs at larger baryon densities. Finally, we present the experimental procedures to extract information on the in-medium masses and widths by fitting final mass spectra at LHC energies.
hep-phnucl-thPRC(2019)·31 citations
05*
A QCD Sum-Rules Analysis of Vector ( $1^{--}$ ) Heavy Quarkonium Meson-Hybrid Mixing
A. Palameta🇨🇦 · J. Ho🇨🇦 · D. Harnett🇨🇦 · T. G. Steele🇨🇦
We use QCD Laplace sum-rules to study meson-hybrid mixing in vector ( $1^{--}$ ) heavy quarkonium. We compute the QCD cross-correlator between a heavy meson current and a heavy hybrid current within the operator product expansion. In addition to leading-order perturbation theory, we include four- and six-dimensional gluon condensate contributions as well as a six-dimensional quark condensate contribution. We construct several single and multi-resonance models that take known hadron masses as inputs. We investigate which resonances couple to both currents and so exhibit meson-hybrid mixing. Compared to single resonance models that include only the ground state, we find that models that also include excited states lead to significantly improved agreement between QCD and experiment. In the charmonium sector, we find that meson-hybrid mixing is consistent with a two-resonance model consisting of the $J / ψ$ and a 4.3~GeV resonance. In the bottomonium sector, we find evidence for meson-hybrid mixing in the $Υ (1 S)$ , $Υ (2 S)$ , $Υ (3 S)$ , and $Υ (4 S)$ .
hep-phPRD(2018)·15 citations
06*
Lepton flavor changing Higgs Boson decays in a Two Higgs Doublet Model with a fourth generation of fermions
S. Chamorro-Solano🇲🇽 · A. Moyotl🇲🇽 · M. A. Pérez🇲🇽
We analyze the flavor changing decay $h \to μτ$ in the framework of a Two Higgs Doublet Model with a fourth generation of fermions (4G2HDM) which couples only to the heavy scalar doublet. We obtain that the respective branching ratio at one-loop level can reach values as high as $1 0^{- 4} - 1 0^{- 6}$ for masses of $300$ GeV to $1$ TeV for the heavy leptons in the fourth family and the new heavy Higgs bosons. These radiative corrections are of the same order of magnitude as the tree level prediction of the 4G2HDM.
hep-phJ.Phys.G(2018)·13 citations
07*
Analytical solutions of the QCD $\otimes$ QED DGLAP evolution equations based on the Mellin transform technique in NLO approximation
Marzieh Mottaghizadeh🇮🇷 · Fatemeh Taghavi Shahri🇮🇷 · Parvin Eslami🇮🇷
In this paper we present a new and efficient analytical solutions for evolving the QED $\otimes$ QCD DGLAP evolution equations in mellin space and obtain the parton distribution functions (PDFs) in perturbative QCD including the QED corrections. The validity of our analytical solutions, which have done in the next to leading order QCD and the leading order QED approximations, are checked with the initial parton distributions from newly released CT14QED global analysis code (Phys. Rev.D93,114015(2016)). The evolved parton distributions are in good agreement with CT14QED code and also with those from APFEL (Computer Physics Communications 185, 1647 (2014)) program.
hep-phPLB(2017)·18 citations
08*
Off-shell Fragmentation
Karoly Urmossy🇵🇱
A new framework is sketched for the treatment of the hadronisation of a highly-virtual quark and anti-quark jet pair created in electron-positron annihilations. As in such a case, factorization theorem does not work, a new scale-evolution equation is proposed for the fragmentation functions. In this approach, the virtuality of the leading parton (taken to be equal to the mass of the jet it induces) is used as fragmentation scale.
hep-phPoS(2018)·1 citation
09*
Study of the in-medium nucleon electromagnetic form factors using a light-front nucleon wave function combined with the quark-meson coupling model
W. R. B. de Aráujo (Secretaria de Educaçao do Estado de São Paulo)🇧🇷 · J.P. B. C. de Melo🇧🇷 · K. Tsushima (Laboratório de Física Teórica e Computacional, Universidade Cruzeiro do Sul)🇧🇷
We study the nucleon electromagnetic (EM) form factors in symmetric nuclear matter as well as in vacuum within a light-front approach using the in-medium inputs calculated by the quark-meson coupling model. The same in-medium quark properties are used as those used for the study of in-medium pion properties. The zero of the proton EM form factor ratio in vacuum, the electric to magnetic form factor ratio $μ_{p} G_{E p} (Q^{2}) / G_{M p} (Q^{2})$ ( $Q^{2} = - q^{2} > 0$ with $q$ being the four-momentum transfer), is determined including the latest experimental data by implementing a hard constituent quark component in the nucleon wave function. A reasonable fit is achieved for the ratio $μ_{p} G_{E p} (Q^{2}) / G_{M p} (Q^{2})$ in vacuum, and we predict that the $Q_{0}^{2}$ value to cross the zero of the ratio to be about 15 GeV $^{2}$ . In addition the double ratio data of the proton EM form factors in $^{4}$ He and H nuclei, $[G_{E p}^{^{4} He} (Q^{2}) / G_{M p}^{^{4} He} (Q^{2})] / [G_{E p}^{^{1} H} (Q^{2}) / G_{M p}^{^{1} H} (Q^{2})]$ , extracted by the polarized ( $e, e^{'} p$ ) scattering experiment on $^{4}$ He at JLab, are well described. We also predict that the $Q_{0}^{2}$ value satisfying $μ_{p} G_{E p} (Q_{0}^{2}) / G_{M p} (Q_{0}^{2}) = 0$ in symmetric nuclear matter, shifts to a smaller value as increasing nuclear matter density, which reflects the facts that the faster falloff of $G_{E p} (Q^{2})$ as increasing $Q^{2}$ and the increase of the proton mean-square charge radius. Furthermore, we calculate the neutron EM form factor double ratio in symmetric nuclear matter for $0.1 < Q^{2} < 1.0$ GeV $^{2}$ . The result shows that the neutron double ratio is enhanced relative to that in vacuum, while for the proton it is quenched, and agrees with an existing theoretical prediction.
hep-phhep-exnucl-exnucl-thNPA(2018)·15 citations
10*
Multiple Parton Interactions, inclusive and exclusive cross sections, sum rules
D. Treleani🇮🇹 · G. Calucci🇮🇹
In a simplified model of Multiple Parton Interactions the inclusive cross sections, of processes with large momentum transfer exchange, acquire the statistical meaning of factorial moments of the distribution in multiplicity of interactions, while more exclusive cross sections, which can provide complementary information on the interaction dynamics, become experimentally viable. Inclusive and exclusive cross sections are linked by sum rules, which can be tested experimentally.
hep-phAdv.Ser.Direct.High Energy Phys.(2018)·6 citations
11*
CP and particle correlations under thermal influence
G. Kozlov🇷🇺
We study the phase transition of nuclear (baryonic) matter in the model of one-dimensional random fluctuation walk. The stochastic fields (forces) influence intrinsic to Bose-Einstein correlations between two identical particles is a particular ingridient of the model. The solution in terms of the characteristic functional equation contains the regular (homogenious) and the singular non-analytical (non-homogenious) parts for baryonic matter (BM) and anomaly matter (AM), respectively. The conditions to phase transition from BM to AM are found.
hep-phhep-th0 citations
12*
Twist-4 contributions to semi-inclusive $e^{+} e^{-}$ -annihilation process
Wei-hua Yang🇨🇳 · Kai-bao Chen🇨🇳 · Zuo-tang Liang (Shandong U.)🇨🇳
We present the complete twist-4 results for the semi-inclusive annihilation process $e^{+} + e^{-} \to h + q ˉ + X$ at the tree level of perturbative quantum chromodynamics. The calculations are carried out by using the formalism obtained by applying the collinear expansion to this process where the multiple gluon scattering is taken into account and gauge links are obtained systematically and automatically. We present the results for structure functions in terms of gauge invariant fragmentation functions up to twist-4 and the corresponding results for the azimuthal asymmetries and polarizations of hadrons produced. The results obtained show in particular that similar to that for semi-inclusive deeply inelastic scattering, for structure functions associated with sine or cosine of odd number of azimuthal angle(s), there are only twist-3 contributions, while for those of even number of azimuthal angle(s), there are leading twist and twist-4 contributions. For all those structure functions that have leading twist contributions, there are twist-4 addenda to them. Hence twist-4 contributions may even have large influences on extracting leading twist fragmentation functions from the data. We also suggest a method for a rough estimation of twist-4 contributions based on the leading twist fragmentation functions.
hep-phPRD(2017)·20 citations
13*
Robustness of dark matter constraints and interplay with collider searches for New Physics
A. Arbey🇫🇷 · M. Boudaud🇫🇷 · F. Mahmoudi🇫🇷 · G. Robbins🇫🇷
We study the implications of dark matter searches, together with collider constraints, on the phenomenological MSSM with neutralino dark matter and focus on the consequences of the related uncertainties in some detail. We consider, inter alia, the latest results from AMS-02, Fermi-LAT and XENON1T. In particular, we examine the impact of the choice of the dark matter halo profile, as well as the propagation model for cosmic rays, for dark matter indirect detection and show that the constraints on the MSSM differ by one to two orders of magnitude depending on the astrophysical hypotheses. On the other hand, our limited knowledge of the local relic density in the vicinity of the Earth and the velocity of Earth in the dark matter halo leads to a factor 3 in the exclusion limits obtained by direct detection experiments. We identified the astrophysical models leading to the most conservative and the most stringent constraints and for each case studied the complementarities with the latest LHC measurements and limits from Higgs, SUSY and monojet searches. We show that combining all data from dark matter searches and colliders, a large fraction of our supersymmetric sample could be probed. Whereas the direct detection constraints are rather robust under the astrophysical assumptions, the uncertainties related to indirect detection can have an important impact on the number of the excluded points.
hep-phastro-ph.HEJHEP(2017)·20 citations
14*
Light scalars, ( $g_{μ} - 2$ ) muon anomaly and dark matter in a model with a Higgs democracy
N.V.Krasnikov🇷🇺
We consider isosinglet scalar extension of a model with a Higgs democracy - multihiggs extension of the SM where each quark and lepton has its own Higgs isodoublet. The addition of light isosinglet scalar allows to solve both muon $g_{μ} - 2$ anomaly and dark matter problem. Also we point out that an extension of the model with $L_{μ} - L_{τ}$ vector interaction allows not only explain muon $g_{μ} - 2$ anomaly but also dark matter density.
hep-ph6 citations
15*
Interpreting the $R_{K^{(*)}}$ Anomaly in the Colored Zee-Babu Model
Shu-Yuan Guo🇨🇳 · Zhi-Long Han🇨🇳 · Bin Li🇨🇳 · Yi Liao🇨🇳 · Xiao-Dong Ma🇨🇳
We consider the feasibility of interpreting the $R_{K^{(*)}}$ anomaly in the colored Zee-Babu model. The model generates neutrino masses at two loops with the help of a scalar leptoquark $S \sim (3, 3, - \frac{1}{3})$ and a scalar diquark $ω \sim (6, 1, - \frac{2}{3})$ , and contributes to the transition $b \to s ℓℓ$ via the exchange of a leptoquark $S$ at tree level. Under constraints from lepton flavor violating (LFV) and flavor changing neutral current (FCNC) processes, and direct collider searches for heavy particles, we acquire certain parameter space that can accommodate the $R_{K^{(*)}}$ anomaly for both normal (NH) and inverted (IH) hierarchies of neutrino masses. We further examine the LFV decays of the $B$ meson, and find its strong correlation with the neutrino mass hierarchy, i.e., $Br (B^{+} \to K^{+} μ^{\pm} τ^{\mp}) ≳ Br (B^{+} \to K^{+} μ^{\pm} e^{\mp}) \approx Br (B^{+} \to K^{+} τ^{\pm} e^{\mp})$ for NH, while $Br (B^{+} \to K^{+} μ^{\pm} τ^{\mp}) ≪ Br (B^{+} \to K^{+} μ^{\pm} e^{\mp}) \approx Br (B^{+} \to K^{+} τ^{\pm} e^{\mp})$ for IH. Among these decays, only $B^{+} \to K^{+} μ^{\pm} e^{\mp}$ in the case of NH is promising at the LHCb RUN II, while for IH all LFV decays are hard to detect in the near future.
hep-phNPB(2018)·35 citations
16*
$Z_{b} (10610)$ and $Z_{b}^{'} (10650)$ decays in a covariant quark model
Fabian Goerke🇩🇪 · Thomas Gutsche🇩🇪 · Mikhail A. Ivanov🇷🇺 · Jürgen G. Körner🇩🇪 · Valery E. Lyubovitskij🇩🇪
We present a calculation of the strong decays of the exotic states $Z_{b} (10610)$ and $Z_{b}^{'} (10650)$ using a covariant quark model. We use a molecular-type four-quark current for the coupling of the $Z_{b} (10610)$ and $Z_{b}^{'} (10650)$ to the constituent heavy and light quarks.
hep-phhep-exPRD(2017)·30 citations
17*
$f_{1} (1285) \to e^{+} e^{-}$ decay and direct $f_{1}$ production in $e^{+} e^{-}$ collisions
A.S. Rudenko🇷🇺
The width of the $f_{1} (1285) \to e^{+} e^{-}$ decay is calculated in the vector meson dominance model. The result depends on the relative phase between two coupling constants describing $f_{1} \to ρ^{0} γ$ decay. The width $Γ (f_{1} \to e^{+} e^{-})$ is estimated to be $≃ 0.07 - 0.19$ eV. Direct $f_{1}$ production in $e^{+} e^{-}$ collisions is discussed, and the $e^{+} e^{-} \to f_{1} \to a_{0} π \to η π π$ cross section is calculated. Charge asymmetry in the $e^{+} e^{-} \to η π^{+} π^{-}$ reaction due to interference between $e^{+} e^{-} \to f_{1}$ and $e^{+} e^{-} \to η ρ^{0}$ amplitudes is studied.
hep-phhep-exPRD(2017)·26 citations
18*
A mixing model for bottomoniumlike $Z_{b}$ resonances
M.B. Voloshin🇺🇸
The isovector bottomoniumlike exotic resonances $Z_{b} (10610)$ and $Z_{b} (10650)$ are very close to the thresholds of heavy meson pairs $B B ˉ^{*} (B ˉ B^{*})$ and $B^{*} B ˉ^{*}$ , and are naturally understood as `molecular' states made of the corresponding meson-antimeson pairs. The picture with a full separation of the two channels cannot be exact and a cross-feed between the states necessarily takes place. A simple model is considered here describing the mixing between the channels in terms of one parameter. The model reasonably describes the current data on the decays of the $Z_{b}$ resonances to bottomonium plus a pion and predicts the rate and a distinctive interference pattern for the decay $Z_{b} (10650) \to B B ˉ^{*} (B ˉ B^{*})$ as well as excess of the mass splitting between the resonances over the mass difference between $B^{*}$ and $B$ mesons.
hep-phhep-exPRD(2017)·7 citations
19*
Couplings in Renormalizable Supersymmetric SO(10) Models
Zhi-Yong Chen🇨🇳 · Da-Xin Zhang🇨🇳 · Xian-Zheng Bai🇨🇳
We study the most general renormalizable couplings containing Higgs $H (10)$ , $D (120)$ , $Δ (126) + Δ (126)$ , $A (45)$ , $E (54)$ and $Φ (210)$ in the supersymmetric SO(10) models. The Clebsch-Gordan Coefficients are calculated using the maximal subgroup $S U (5) \times U (1)_{X}$ .
hep-phInt.J.Mod.Phys.A(2017)·6 citations
20*
CT14 Intrinsic Charm Parton Distribution Functions from CTEQ-TEA Global Analysis
Tie-Jiun Hou🇺🇸 · Sayipjamal Dulat🇨🇳 · Jun Gao🇨🇳 · Marco Guzzi🇬🇧 · Joey Huston🇺🇸 · Pavel Nadolsky🇺🇸 · Carl Schmidt🇺🇸 · Jan Winter🇺🇸 · Keping Xie🇺🇸 · C.-P. Yuan🇺🇸
We investigate the possibility of a (sizable) nonperturbative contribution to the charm parton distribution function (PDF) in a nucleon, theoretical issues arising in its interpretation, and its potential impact on LHC scattering processes. The "fitted charm" PDF obtained in various QCD analyses contains a process-dependent component that is partly traced to power-suppressed radiative contributions in DIS and is generally different at the LHC. We discuss separation of the universal component of the nonperturbative charm from the rest of the radiative contributions and estimate its magnitude in the CT14 global QCD analysis at the next-to-next-to leading order in the QCD coupling strength, including the latest experimental data from HERA and the Large Hadron Collider. Models for the nonperturbative charm PDF are examined as a function of the charm quark mass and other parameters. The prospects for testing these models in the associated production of a Z boson and a charm jet at the LHC are studied under realistic assumptions, including effects of the final-state parton showering.
hep-phJHEP(2018)·111 citations
21*
Electron-positron annihilation into hadrons at the higher-loop levels
A.V.Nesterenko🇷🇺
The strong corrections to the R-ratio of electron-positron annihilation into hadrons are studied at the higher-loop levels. Specifically, the essentials of continuation of the spacelike perturbative results into the timelike domain are elucidated. The derivation of a general form of the commonly employed approximate expression for the R-ratio (which constitutes its truncated re-expansion at high energies) is delineated, the appearance of the pertinent $π^{2}$ -terms is expounded, and their basic features are examined. It is demonstrated that the validity range of such approximation is strictly limited to $s /Λ > exp (π /2) ≃ 4.81$ and that it converges rather slowly when the energy scale approaches this value. The spectral function required for the proper calculation of the R-ratio is explicitly derived and its properties at the higher-loop levels are studied. The developed method of calculation of the spectral function enables one to obtain the explicit expression for the latter at an arbitrary loop level. By making use of the derived spectral function the proper expression for the R-ratio is calculated up to the five-loop level and its properties are examined. It is shown that the loop convergence of the proper expression for the R-ratio is better than that of its commonly employed approximation. The impact of the omitted higher-order $π^{2}$ -terms on the latter is also discussed.
hep-phhep-exEPJC(2017)·29 citations
22*
Axion-photon conversion caused by dielectric interfaces: quantum field calculation
Ara N. Ioannisian🇦🇲 · Narine Kazarian🇦🇲 · Alexander J. Millar🇩🇪 · Georg G. Raffelt🇩🇪
Axion-photon conversion at dielectric interfaces, immersed in a near-homogeneous magnetic field, is the basis for the dielectric haloscope method to search for axion dark matter. In analogy to transition radiation, this process is possible because the photon wave function is modified by the dielectric layers ("Garibian wave function") and is no longer an eigenstate of momentum. A conventional first-order perturbative calculation of the transition probability between a quantized axion state and these distorted photon states provides the microwave production rate. It agrees with previous results based on solving the classical Maxwell equations for the combined system of axions and electromagnetic fields. We argue that in general the average photon production rate is given by our result, independently of the detailed quantum state of the axion field. Moreover, our result provides a new perspective on axion-photon conversion in dielectric haloscopes because the rate is based on an overlap integral between unperturbed axion and photon wave functions, in analogy to the usual treatment of microwave-cavity haloscopes.
hep-phastro-ph.COhep-exJCAP(2017)·44 citations
23*
Projected bounds on ALPs from Athena
Joseph P. Conlon🇬🇧 · Francesca Day🇬🇧 · Nicholas Jennings🇬🇧 · Sven Krippendorf🇬🇧 · Francesco Muia🇬🇧
Galaxy clusters represent excellent laboratories to search for Axion-Like Particles (ALPs). They contain magnetic fields which can induce quasi-sinusoidal oscillations in the X-ray spectra of AGNs situated in or behind them. Due to its excellent energy resolution, the X-ray Integral Field Unit (X-IFU) instrument onboard the Athena X-ray Observatory will be far more sensitive to ALP-induced modulations than current detectors. As a first analysis of the sensitivity of Athena to the ALP-photon coupling $g_{aγ γ}$ , we simulate observations of the Seyfert galaxy NGC1275 in the Perseus cluster using the SIXTE simulation software. We estimate that for a 200ks exposure, a non-observation of spectral modulations will constrain $g_{aγ γ} ≲ 1.5 \times 1 0^{- 13} GeV^{- 1}$ for $m_{a} ≲ 1 0^{- 12} eV$ , representing an order of magnitude improvement over constraints derived using the current generation of satellites.
↳ astro-ph.HEhep-phMNRAS(2018)·29 citations
24*
Axion Production from Landau Quantization in the Strong Magnetic Field of Magnetars
Tomoyuki Maruyama🇯🇵 · A. Baha Balantekin🇺🇸 · Myung-Ki Cheoun🇰🇷 · Toshitaka Kajino🇯🇵 · Grant J. Mathews🇺🇸
We utilize an exact quantum calculation to explore axion emission from electrons and protons in the presence of the strong magnetic field of magnetars. The axion is emitted via transitions between the Landau levels generated by the strong magnetic field. The luminosity of axions emitted by protons is shown to be much larger than that of electrons and becomes stronger with increasing matter density. Cooling by axion emission is shown to be much larger than neutrino cooling by the Urca processes. Consequently, axion emission in the crust may significantly contribute to the cooling of magnetars. In the high-density core, however, it may cause heating of the magnetar.
↳ astro-ph.HEhep-phnucl-thPLB(2018)·15 citations
25*
Constraints on the sum of neutrino masses using cosmological data including the latest extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample
Sai Wang🇨🇳 · Yi-Fan Wang🇨🇳 · Dong-Mei Xia🇨🇳
We investigate the constraints on the sum of neutrino masses ( $Σ m_{ν}$ ) using the most recent cosmological data, which combines the distance measurement from baryonic acoustic oscillation in the extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample with the power spectra of temperature and polarization anisotropies in the cosmic microwave background from the Planck 2015 data release. We also use other low-redshift observations including the baryonic acoustic oscillation at relatively low redshifts, the supernovae of type Ia and the local measurement of Hubble constant. In the standard cosmological constant $Λ$ cold dark matter plus massive neutrino model, we obtain the $95%$ \acl{CL} upper limit to be $Σ m_{ν} < 0.129 eV$ for the degenerate mass hierarchy, $Σ m_{ν} < 0.159 eV$ for the normal mass hierarchy, and $Σ m_{ν} < 0.189 eV$ for the inverted mass hierarchy. Based on Bayesian evidence, we find that the degenerate hierarchy is positively supported, and the current data combination can not distinguish normal and inverted hierarchies. Assuming the degenerate mass hierarchy, we extend our study to non-standard cosmological models including the generic dark energy, the spatial curvature, and the extra relativistic degrees of freedom, respectively, but find these models not favored by the data.
↳ astro-ph.COhep-phhep-thCPC(2018)·49 citations
26*
Machine Learning in the String Landscape
Jonathan Carifio🇺🇸 · James Halverson🇺🇸 · Dmitri Krioukov🇺🇸 · Brent D. Nelson🇺🇸
We utilize machine learning to study the string landscape. Deep data dives and conjecture generation are proposed as useful frameworks for utilizing machine learning in the landscape, and examples of each are presented. A decision tree accurately predicts the number of weak Fano toric threefolds arising from reflexive polytopes, each of which determines a smooth F-theory compactification, and linear regression generates a previously proven conjecture for the gauge group rank in an ensemble of $\frac{4}{3} \times 2.96 \times 1 0^{755}$ F-theory compactifications. Logistic regression generates a new conjecture for when $E_{6}$ arises in the large ensemble of F-theory compactifications, which is then rigorously proven. This result may be relevant for the appearance of visible sectors in the ensemble. Through conjecture generation, machine learning is useful not only for numerics, but also for rigorous results.
↳ hep-thhep-phJHEP(2017)·173 citations
27*
Frame-dependence of higher-order inflationary observables in scalar-tensor theories
Alexandros Karam🇬🇷 · Thomas Pappas🇬🇷 · Kyriakos Tamvakis🇬🇷
In the context of scalar-tensor theories of gravity we compute the third-order corrected spectral indices in the slow-roll approximation. The calculation is carried out by employing the Green's function method for scalar and tensor perturbations in both the Einstein and Jordan frames. Then, using the interrelations between the Hubble slow-roll parameters in the two frames we find that the frames are equivalent up to third order. Since the Hubble slow-roll parameters are related to the potential slow-roll parameters, we express the observables in terms of the latter which are manifestly invariant. Nevertheless, the same inflaton excursion leads to different predictions in the two frames since the definition of the number of e-folds differs. To illustrate this effect we consider a nonminimal inflationary model and find that the difference in the predictions grows with the nonminimal coupling and it can actually be larger than the difference between the first and third order results for the observables. Finally, we demonstrate the effect of various end-of-inflation conditions on the observables. These effects will become important for the analyses of inflationary models in view of the improved sensitivity of future experiments.
↳ gr-qcastro-ph.COhep-phhep-thPRD(2017)·105 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.