HEP Phenomenology·hep-ph

Thu·Dec 8, 2016Thursday·December 8, 2016

32 papers—21 primary·11 cross-listed·reconstructed*

01*
The landscape of $W^{\pm}$ and $Z$ bosons produced in $pp$ collisions up to LHC energies
Eduardo Basso🇧🇷 · Claude Bourrely🇫🇷 · Roman Pasechnik🇸🇪 · Jacques Soffer🇺🇸
We consider a selection of recent experimental results on electroweak $W^{\pm}, Z$ gauge boson production in $pp$ collisions at BNL RHIC and CERN LHC energies in comparison to prediction of perturbative QCD calculations based on different sets of NLO parton distribution functions including the statistical PDF model known from fits to the DIS data. We show that the current statistical PDF parameterisation (fitted to the DIS data only) underestimates the LHC data on $W^{\pm}, Z$ gauge boson production cross sections at the NLO by about 20\%. This suggests that there is a need to refit the parameters of the statistical PDF including the latest LHC data.
hep-phNPA(2017)·1 citation
02*
A revisit to scalar dark matter with radiative corrections
Shankha Banerjee🇫🇷 · Nabarun Chakrabarty🇮🇳
Extended Higgs sectors have been studied extensively in context of dark matter phenomenology in tandem with other aspects. In this study, we compute radiative corrections to the dark matter-Higgs portal coupling, which is in fact a common feature of all scalar dark matter models irrespective of the hypercharge of the multiplet from which the dark matter candidate emerges. We select the popular inert doublet model (IDM) as a prototype in order to demonstrate the impact of the next-to-leading order corrections, thereby probing the plausibility of extending the allowed parameter space through quantum effects. Given that the tree level portal coupling is a \emph{prima facie} free parameter, the percentage change from loop effects can be large. This modifies the dark matter phenomenology at a quantitative level. It also encourages one to include loop corrections to all other interactions that are deemed relevant in this context.
hep-phhep-exJHEP(2019)·23 citations
03*
Precision neutrino experiments vs the Littlest Seesaw
Peter Ballett🇬🇧 · Stephen F. King🇬🇧 · Silvia Pascoli🇬🇧 · Nick W. Prouse🇬🇧 · TseChun Wang🇬🇧
We study to what extent upcoming precision neutrino oscillation experiments will be able to exclude one of the most predictive models of neutrino mass and mixing: the Littlest Seesaw. We show that this model provides a good fit to current data, predicting eight observables from two input parameters, and provide new assessments of its predictions and their correlations. We then assess the ability to exclude this model using simulations of upcoming neutrino oscillation experiments including the medium-distance reactor experiments JUNO and RENO-50 and the long-baseline accelerator experiments DUNE and T2HK. We find that an accurate determination of the currently least well measured parameters, namely the atmospheric and solar angles and the CP phase $δ$ , provide crucial independent tests of the model. For $θ_{13}$ and the two mass-squared differences, however, the model's exclusion requires a combination of measurements coming from a varied experimental programme. Our results show that the synergy and complementarity of future experiments will play a vital role in efficiently discriminating between predictive models of neutrino flavour, and hence, towards advancing our understanding of neutrino oscillations in the context of the flavour puzzle of the Standard Model.
hep-phhep-exJHEP(2017)·53 citations
04*
Particle Dark Matter Constraints: the Effect of Galactic Uncertainties
Maria Benito🇧🇷 · Nicolas Bernal🇨🇴 · Nassim Bozorgnia🇳🇱 · Francesca Calore🇳🇱 · Fabio Iocco🇧🇷
Collider, space, and Earth based experiments are now able to probe several extensions of the Standard Model of particle physics which provide viable dark matter candidates. Direct and indirect dark matter searches rely on inputs of astrophysical nature, such as the local dark matter density or the shape of the dark matter profile in the target in object. The determination of these quantities is highly affected by astrophysical uncertainties. The latter, especially those for our own Galaxy, are ill-known, and often not fully accounted for when analyzing the phenomenology of particle physics models. In this paper we present a systematic, quantitative estimate of how astrophysical uncertainties on Galactic quantities (such as the local galactocentric distance, circular velocity, or the morphology of the stellar disk and bulge) propagate to the determination of the phenomenology of particle physics models, thus eventually affecting the determination of new physics parameters. We present results in the context of two specific extensions of the Standard Model (the Singlet Scalar and the Inert Doublet) that we adopt as case studies for their simplicity in illustrating the magnitude and impact of such uncertainties on the parameter space of the particle physics model itself. Our findings point toward very relevant effects of current Galactic uncertainties on the determination of particle physics parameters, and urge a systematic estimate of such uncertainties in more complex scenarios, in order to achieve constraints on the determination of new physics that realistically include all known uncertainties.
hep-phastro-ph.GAJCAP(2017)·67 citations
05*
On the non-minimal character of the SMEFT
Yun Jiang🇩🇰 · Michael Trott🇩🇰
When integrating out unknown new physics sectors, what is the minimal character of the Standard Model Effective Field Theory (SMEFT) that can result? In this paper we focus on a particular aspect of this question: "How can one obtain only one dimension six operator in the SMEFT from a consistent tree level matching onto an unknown new physics sector?" We show why this requires conditions on the ultraviolet field content that do not indicate a stand alone ultraviolet complete scenario. Further, we demonstrate how a dynamical origin of the ultraviolet scales assumed to exist in order to generate the masses of the heavy states integrated out generically induces more operators. Therefore, our analysis indicates that the infrared limit captured from a new sector in consistent matchings induces multiple operators in the SMEFT quite generically. Global data analyses in the SMEFT can and should accommodate this fact.
hep-phPLB(2017)·30 citations
06*
Viscous Conformal Gauge Theories
Arianna Toniato🇩🇰 · Francesco Sannino🇩🇰 · Dirk H. Rischke🇩🇪
We present the conformal behavior of the shear viscosity-to-entropy density ratio and the fermion-number diffusion coefficient within the perturbative regime of the conformal window for gauge-fermion theories.
hep-phhep-lathep-thPRD(2017)·0 citations
07*
2HDM Charged Higgs Boson Searches at the LHC: Status and Prospects
Stefano Moretti🇬🇧
We review status and prospects of searches for the charged Higgs boson of 2-Higgs Doublet Models of all Yukawa types at the Large Hadron Collider
hep-phPoS(2016)·19 citations
08*
Reggeized model for $γ p \to ρ^{-} Δ^{++} (1232)$ photoproduction
Byung-Geel Yu🇰🇷 · Kook-Jin Kong🇰🇷
A model for the reaction $γ p \to ρ^{-} Δ^{++}$ is presented with the $t$ -channel $π + ρ$ exchanges reggeized to describe the reaction up to high energies. Gauge invariance of $ρ$ exchange is discussed in connection with the convergence of the reaction cross section at high energy. The roles of electromagnetic (EM) multipole moments of $Δ^{++}$ baryon and of $ρ^{-}$ meson are analyzed in total and differential cross sections and spin density matrix elements. Photon polarization asymmetry $Σ$ is predicted for a measurement of electromagnetic moments of $ρ^{-}$ and of $Δ^{++}$ .
hep-phnucl-thJ.Phys.G(2020)·3 citations
09*
Neutrino and CP-even Higgs boson masses in a nonuniversal $U (1)^{'}$ extension
S.F. Mantilla🇨🇴 · R. Martinez🇨🇴 · F. Ochoa🇨🇴
We propose a new anomaly-free and family nonuniversal $U (1)^{'}$ extension of the standard model with the addition of two scalar singlets and a new scalar doublet. The quark sector is extended by adding three exotic quark singlets, while the lepton sector includes two exotic charged lepton singlets, three right-handed neutrinos and three sterile Majorana leptons to obtain the fermionic mass spectrum of the standard model. The lepton sector also reproduces the elements of the PMNS matrix and the squared-mass differences data from neutrino oscillation experiments. Also, analytical relations of the PMNS matrix are derived via the inverse see-saw mechanism, and numerical predictions of the parameters in both normal and inverse order scheme for the mass of the phenomenological neutrinos are obtained. We employed a simple seesaw-like method to obtain analytical mass eigenstates of the CP-even $3 \times 3$ mass matrix of the scalar sector.
hep-phPRD(2017)·24 citations
10*
$B \to X_{_{S}} l^{+} l^{-}$ in the minimal gauged $(B - L)$ supersymmetry
Tai-Fu Feng🇨🇳 · Jin-Lei Yang🇨🇳 · Hai-Bin Zhang🇨🇳 · Shu-Min Zhao🇨🇳 · Rong-Fei Zhu🇨🇳
Applying the effective Hamilton for $b \to s l^{+} l^{-}, (l = e, μ)$ in the framework of minimal supersymmetric extension of the standard model with local $B - L$ gauge symmetry, we investigate branching ratios and forward-backward asymmetries of rare decay $B \to X_{_{S}} l^{+} l^{-}$ in low and high $q^{2}$ regions, respectively. In addition we also study the $C P$ asymmetries depending on new $C P$ phases from soft breaking terms in low and high $q^{2}$ regions. With some assumptions on parameter space of the model, the numerical analyses of the supersymmetric contributions to the branching ratios, forward-backward and $C P$ asymmetries of $B \to X_{_{S}} l^{+} l^{-}$ are presented in low and high $q^{2}$ regions, respectively.
hep-phPRD(2016)·7 citations
11*
Radiative corrections to elastic proton-electron scattering measured in coincidence
G.I. Gakh🇺🇦 · M.I. Konchatnij🇺🇦 · N.P. Merenkov🇺🇦 · Egle Tomasi-Gustafsson🇫🇷
The differential cross section for elastic scattering of protons on electrons at rest is calculated taking into account the QED radiative corrections to the leptonic part of interaction. These model-independent radiative corrections arise due to emission of the virtual and real soft and hard photons as well as to vacuum polarization. We analyze an experimental setup when both the final particles are recorded in coincidence and their energies are determined within some uncertainties. The kinematics, the cross section, and the radiative corrections are calculated and numerical results are presented.
hep-phnucl-thPRC(2017)·5 citations
12*
Magnetic Catalysis in the Higher-Order Quark Sigma Model
M. Abu-Shady🇪🇬
The effect of the higher-order mesonic interactions is investigated on the chiral symmetry breaking in the presence of an external magnetic field. The effective of higher-order mesonic potential is employed and is numerically solved in the mean-field approximation. The chiral symmetry breaking increases with increasing magnetic field. Two sets of free parameterization are investigated on the magnetic catalysis. A comparison is discussed with the original sigma model and other studies. The obtained results are included that the higher-order mesonic interactions play an important role in the magnetic catalysis.
hep-phJ.Part.Phys.(2017)·1 citation
13*
Space anisotropy search at colliders
I.S. Karpikov🇷🇺 · D.V. Kirpichnikov🇷🇺 · D.A. Tlisov🇷🇺
In the framework of model with Lorentz violation (LV) we discuss a physical observables for $q q ˉ$ pair production at lepton-lepton colliders and describe the experimental signal to be detected. We obtain a conservative limits on Lorentz-violating dimensionless coupling for quark sector from LEP data. We also make a phenomenological prediction for LV model at the future lepton collider.
hep-phPhys.Atom.Nucl.(2018)·9 citations
14*
Sub-GeV-scale signatures of hidden braneworlds up to the Planck scale in a $S O (3, 1)$ -broken bulk
Coraline Stasser🇧🇪 · Michael Sarrazin🇧🇪
Many-brane universes are at the heart of several cosmological scenarios related to physics beyond the Standard Model. It is then a major concern to constrain these approaches. Two-brane Universes involving $S O (3, 1)$ -broken 5D bulks are among the cosmological models of interest. They also allow considering matter exchange between branes, a possible way to test these scenarios. Neutron disappearance (reappearance) toward (from) the hidden brane is currently tested with high-precision experiments to constrain the coupling constant $g$ between the visible and hidden neutron sectors. When dealing with the sub-GeV-scale quantum dynamics of fermions, any pair of braneworlds can be described by a non-commutative two-sheeted space-time $M_{4} \times Z_{2}$ from which $g$ emerges. Nevertheless, the calculation of the formal link between $g$ for a neutron and $S O (3, 1)$ -broken 5D bulks remains an open problem until now although necessary to constrain these braneworld scenarios. Thanks to a phenomenological model, we derive $g$ - for a neutron - between the two braneworlds endowed with their own copy of the standard model in a $S O (3, 1)$ -broken 5D bulk. Constraints on interbrane distance and brane energy scale (or brane thickness) are discussed. While brane energy scale below the GUT scale is excluded, energy scale up to the Planck limit allows neutron swapping detection in forthcoming experiments.
hep-phhep-exInt.J.Mod.Phys.A(2019)·8 citations
15*
Excited lepton baryogenesis
Dmitry Zhuridov🇵🇱
The excited leptons that share the quantum numbers with the Standard Model leptons but have larger masses are widespread in many promising new physics theories. A subclass of excited leptons that at low energies interact with the SM fermions dominantly through the effective coupling to lepton and fermion-antifermion pair can be referred as leptomesons. I introduce possible generation of the baryon asymmetry of the universe using these new particles. The discussed baryogenesis mechanisms do not contradict to the small neutrino masses and the proton stability, and can be interesting for the collider experiments.
hep-phEPJ Web Conf.(2017)·0 citations
16*
Heavy quark state production in Pb-Pb collisions at $s_{N N}$ =5.02 TeV
Leonard S. Kisslinger🇺🇸 · Debasish Das🇮🇳
We estimate differential rapidity cross sections for $J /Ψ$ , $Ψ (2 S)$ , $Υ (1 S)$ , $Υ (2 S)$ , and $Υ (3 S)$ production via Pb-Pb collisions at proton-proton energy $\equiv s_{pp}$ =5.02 TeV. For the $Ψ (2 S)$ , $Υ (3 S)$ states we use the mixed heavy quark hyrid theory, with these states being approximately 50\% standard and 50\% hybrid charmonium, bottomonium meson states. This is an extension of previous work on heavy quark state production via Cu-Cu and Au-Au collisions at $s_{pp}$ =200 GeV.
hep-phJHEP(2017)·6 citations
17*
CP-violating decays of the pseudoscalars eta and eta' and their connection to the electric dipole moment of the neutron
Thomas Gutsche🇩🇪 · Astrid N. Hiller Blin🇪🇸 · Sergey Kovalenko🇨🇱 · Serguei Kuleshov🇨🇱 · Valery E. Lyubovitskij🇩🇪 · Manuel J. Vicente Vacas🇪🇸 · Alexey Zhevlakov🇷🇺
Using the present upper bound on the neutron electric dipole moment, we give an estimate for the upper limit of the CP-violating couplings of the eta(eta') to the nucleon. Using this result, we then derive constraints on the CP-violating eta(eta')-pi-pi couplings, which define the two-pion CP-violating decays of the eta and eta' mesons. Our results are relevant for the running and planned measurements of rare decays of the eta and eta' mesons by the GlueX Collaboration at JLab and the LHCb Collaboration at CERN.
hep-phPRD(2017)·27 citations
18*
Results from TopFitter
Andy Buckley🇬🇧 · Christoph Englert🇬🇧 · James Ferrando🇩🇪 · David J. Miller🇬🇧 · Liam Moore🇧🇪 · Karl Nordström🇬🇧 · Michael Russell🇬🇧 · Chris D. White🇬🇧
We discuss a global fit of top quark BSM couplings, phrased in the model-independent language of higher-dimensional effective operators, to the currently available data from the LHC and Tevatron. We examine the interplay between inclusive and differential measurements, and the complementarity of LHC and Tevatron results. We conclude with a discussion of projections for improvement over LHC Run II.
hep-phPoS(2016)·16 citations
19*
Status of CMSSM in light of current LHC Run-2 and LUX data
Chengcheng Han🇯🇵 · Ken-ichi Hikasa🇯🇵 · Lei Wu🇨🇳 · Jin Min Yang🇨🇳 · Yang Zhang🇨🇳
Motivated by the latest results of the LHC Run-2 and LUX experiments, we examine the status of the constrained minimal supersymmetric standard model (CMSSM) by performing a global fit. We construct a likelihood function including the electroweak precision observables, $B$ -physics measurements, LHC Run-1 and -2 data of SUSY direct searches, Planck observation of the dark matter relic density and the combined LUX Run-3 and -4 detection limits. Based on the profile likelihood functions of 1 billion samples, we obtain the following observations: (i) The stau coannihilation region has been mostly excluded by the latest LHC Run-2 data; (ii) The focus point region has been largely covered by the LUX-2016 limits while the $A$ -funnel region has been severely restricted by flavor observables like $B_{s} \to μ^{+} μ^{-}$ . The remaining parts of both regions will be totally covered by the future LZ dark matter experiment; (iii) The masses of the stop, the lightest neutralino and the gluino have been pushed up to 1033 GeV, 449 GeV and 2285 GeV, respectively.
hep-phhep-exPLB(2017)·65 citations
20*
Neutrino-induced one-pion production revisited: the $ν_{μ} n \to μ^{-} n π^{+}$ channel
E. Hernández🇪🇸 · J. Nieves🇪🇸
Understanding single pion production reactions on free nucleons is the first step towards a correct description of these processes in nuclei, which are important for signal and background contributions in current and near future accelerator neutrino oscillation experiments. In this work, we reanalyze our previous studies of neutrino-induced one-pion production on nucleons for outgoing $π N$ invariant masses below 1.4 GeV. Our motivation is to get a better description of the $ν_{μ} n \to μ^{-} n π^{+}$ cross section, for which current theoretical models give values significantly below data. This channel is very sensitive to the crossed $Δ (1232)$ contribution and thus to spin 1/2 components in the Rarita-Schwinger $Δ$ propagator. We show how these spin 1/2 components are nonpropagating and give rise to contact interactions. In this context, we point out that the discrepancy with experiment might be corrected by the addition of appropriate extra contact terms and argue that this procedure will provide a natural solution to the $ν_{μ} n \to μ^{-} n π^{+}$ puzzle. To keep our model simple, in this work we propose to change the strength of the spin 1/2 components in the $Δ$ propagator and use the $ν_{μ} n \to μ^{-} n π^{+}$ data to constraint its value. With this modification, we now find a good reproduction of the $ν_{μ} n \to μ^{-} n π^{+}$ cross section without affecting the good results previously obtained for the other channels. We also explore how this change in the $Δ$ propagator affects our predictions for pion photoproduction and find also a better agreement with experiment than with the previous model.
hep-phnucl-thPRD(2017)·39 citations
21*
Supersymmetry Across the Light and Heavy-Light Hadronic Spectrum II
Hans Gunter Dosch🇩🇪 · Guy F. de Teramond🇨🇷 · Stanley J. Brodsky🇺🇸
We extend our analysis of the implications of hadronic supersymmetry for heavy-light hadrons in light-front holographic QCD. Although conformal symmetry is strongly broken by the heavy quark mass, supersymmetry and the holographic embedding of semiclassical light-front dynamics derived from five-dimensional anti-de Sitter (AdS) space nevertheless determines the form of the confining potential in the light-front Hamiltonian to be harmonic. The resulting light-front bound-state equations lead to a heavy-light Regge-like spectrum for both mesons and baryons. The confinement hadron mass scale and their Regge slopes depend, however, on the mass of the heavy quark in the meson or baryon as expected from Heavy Quark Effective Theory (HQET). This procedure reproduces the observed spectra of heavy-light hadrons with good precision and makes predictions for yet unobserved states.
hep-phhep-thPRD(2017)·58 citations
22*
Non-Fermi liquid Superconductivity: Eliashberg versus the Renormalization Group
Huajia Wang🇺🇸 · Srinivas Raghu🇺🇸 · Gonzalo Torroba🇦🇷
We address the problem of superconductivity for non-Fermi liquids using two commonly adopted, yet apparently distinct methods: 1) the renormalization group (RG) and 2) Eliashberg theory. The extent to which both methods yield consistent solutions for the low energy behavior of quantum metals has remained unclear. We show that the perturbative RG beta function for the 4-Fermi coupling can be explicitly derived from the linearized Eliashberg equations, under the assumption that quantum corrections are approximately local across energy scales. We apply our analysis to the test case of phonon mediated superconductivity and show the consistency of both the Eliashberg and RG treatments. We next study superconductivity near a class of quantum critical points and find a transition between superconductivity and a "naked" metallic quantum critical point with finite, critical BCS couplings. We speculate on the applications of our theory to the phenomenology of unconventional metals.
↳ cond-mat.str-elcond-mat.supr-conhep-phhep-thPRB(2017)·29 citations
23*
New terms for scalar multi-Galileon models and application to SO(N) and SU(N) group representations
Erwan Allys🇫🇷
We investigate a new class of scalar multi-galileon models, which is not included in the commonly admitted general formulation of generalized multi-galileons. The Lagrangians of this class of models, some of them having already been introduced in previous works, are specific to multi-galileon theories, and vanish in the single galileon case. We examine them in details, discussing in particular some hidden symmetry properties which can be made explicit by adding total derivatives to these Lagrangians. These properties allow us to describe the possible dynamics for these new Lagrangians in the case of multi-galileons in the fundamental representation of a SO(N) and SU(N) global symmetry group, as well as in the adjoint representation of a SU(N) global symmetry group. We perform in parallel an exhaustive examination of some of these models, finding a complete agreement with the dynamics obtained using the symmetry properties. Finally, we conclude by discussing what could be the most general multi-galileon theory, as well as the link between scalar and vector multi-galileon models.
↳ hep-thgr-qchep-phPRD(2017)·26 citations
24*
Lepton asymmetry, neutrino spectral distortions, and big bang nucleosynthesis
E. Grohs🇺🇸 · George M. Fuller🇺🇸 · C. T. Kishimoto🇺🇸 · Mark W. Paris🇺🇸
We calculate Boltzmann neutrino energy transport with self-consistently coupled nuclear reactions through the weak-decoupling-nucleosynthesis epoch in an early universe with significant lepton numbers. We find that the presence of lepton asymmetry enhances processes which give rise to nonthermal neutrino spectral distortions. Our results reveal how asymmetries in energy and entropy density uniquely evolve for different transport processes and neutrino flavors. The enhanced distortions in the neutrino spectra alter the expected big bang nucleosynthesis light element abundance yields relative to those in the standard Fermi-Dirac neutrino distribution cases. These yields, sensitive to the shapes of the neutrino energy spectra, are also sensitive to the phasing of the growth of distortions and entropy flow with time/scale factor. We analyze these issues and speculate on new sensitivity limits of deuterium and helium to lepton number.
↳ astro-ph.COhep-phPRD(2017)·29 citations
25*
The effect of magnetization and electric polarization on the anomalous transport coefficients of a chiral fluid
N. Sadooghi🇮🇷 · S.M.A. Tabatabaee🇮🇷
The effects of finite magnetization and electric polarization on dissipative and non-dissipative (anomalous) transport coefficients of a chiral fluid are studied. First, using the second law of thermodynamics as well as Onsager's time reversal symmetry principle, the complete set of dissipative transport coefficients of this medium is derived. It is shown that the properties of the resulting shear and bulk viscosities are mainly affected by the anisotropy induced by external electric and magnetic fields. Then, using the fact that the anomaly induced currents do not contribute to entropy production, the corresponding algebro-differential equations to non-dissipative anomalous transport coefficients are derived in a certain derivative expansion. The solutions of these equations show that, within this approximation, anomalous transport coefficients are, in particular, given in terms of the electric susceptibility of the medium.
↳ hep-thhep-phnucl-thNew J.Phys.(2017)·7 citations
26*
Lecture Notes on Multi-loop Integral Reduction and Applied Algebraic Geometry
Yang Zhang🇨🇭
These notes are for the author's lectures, "Integral Reduction and Applied Algebraic Geometry Techniques" in the School and Workshop on Amplitudes in Beijing 2016. I introduce the applications of algebraic geometry methods on multi-loop scattering amplitudes, for instance, integrand reduction, residue computation in unitarity analysis and Integration-by-parts reduction. Illustrative examples and exercises are included in these notes.
↳ hep-thhep-phmath-phmath.MP76 citations
27*
Constraining the interaction between dark matter and dark energy with CMB data
Riccardo Murgia🇮🇹
We briefly discuss the intriguing case of a phenomenological non-gravitational coupling in the dark sector, where the interaction is parameterized as an energy transfer either from dark matter to dark energy or the opposite. We show that a non-zero coupling with an energy flow from the latter to the former leads to a full reconciliation of the tension between high- and low-redshift observations present in the standard cosmological model.
↳ astro-ph.COhep-ph5 citations
28*
Slope and curvature of the hadron vacuum polarization at vanishing virtuality from lattice QCD
Sz. Borsanyi🇩🇪 · Z. Fodor🇩🇪 · T. Kawanai🇩🇪 · S. Krieg🇩🇪 · L. Lellouch🇫🇷 · R. Malak🇫🇷 · K. Miura🇫🇷 · K.K. Szabo🇩🇪 · C. Torrero🇫🇷 · B. Toth🇩🇪
We compute the slope and curvature, at vanishing four-momentum transfer squared, of the leading order hadron vacuum polarization function, using lattice QCD. Calculations are performed with 2+1+1 flavors of staggered fermions directly at the physical values of the quark masses and in volumes of linear extent larger than 6fm. The continuum limit is carried out using six different lattice spacings. All connected and disconnected contributions are calculated, up to and including those of the charm.
↳ hep-lathep-phPRD(2017)·60 citations
29*
Charm Production and QCD Analysis at HERA and LHC
Oleksandr Zenaiev🇩🇪
This review is devoted to the study of charm production in ep and pp collisions. The total set of measurements obtained by the two collaborations H1 and ZEUS from HERA and their combination is outlined, as well as complementary data obtained by the LHCb collaboration at the LHC. After fitting the parton distribution functions the charm production cross sections are predicted within perturbative QCD at next-to-leading order using the fixed-flavour-number scheme. Agreement with the data is found. The combined HERA charm data are sensitive to the $c$ -quark mass and enabled its accurate determination. The predictions crucially depend upon the knowledge of the gluon distribution function. It is shown that the shape of the gluon distribution based on the HERA data is considerably improved by adding the measurements from LHCb and applicable down to values x of about 10^{-6}, where x is the proton momentum fraction carried by a parton.
↳ hep-exhep-phEPJC(2017)·13 citations
30*
Towards Background-free RENP using a Photonic Crystal Waveguide
Minoru Tanaka🇯🇵 · Koji Tsumura🇯🇵 · Noboru Sasao🇯🇵 · Motohiko Yoshimura🇯🇵
We study how to suppress multiphoton emission background in QED against radiative emission of neutrino pair (RENP) from atoms. We purse the possibility of background suppression using the photonic band structure of periodic dielectric media, called photonic crystals. The modification of photon emission rate in photonic crystal waveguides is quantitatively examined to clarify the condition of background-free RENP.
↳ physics.opticshep-exhep-phPTEP(2017)·6 citations
31*
Notes on Born-Infeld-type electrodynamics
S. I. Kruglov🇨🇦
We propose a new model of nonlinear electrodynamics with three parameters. Born-Infeld electrodynamics and exponential electrodynamics are particular cases of this model. The phenomenon of vacuum birefringence is studied. We show that there is not singularity of the electric field at the origin of point-like charged particles. The corrections to Coulomb's law at $r \to \infty$ are obtained. We calculate the total electrostatic energy of charges for different parameters of the model which is finite.
↳ physics.gen-phhep-phMod.Phys.Lett.A(2017)·37 citations
32*
Electron Positron Pair Production in Strong Electric Fields
Alexander Blinne🇩🇪
This work covers electron positron pair production in spatially homogeneous electric (and magnetic) fields. Different field configurations are looked at in order to study various phenomena including multiphoton pair production, Sauter-Schwinger pair production and dynamically assisted pair production. The main focus lies on pulsed, rotating fields with one main frequency component which are called rotating Sauter pulses. The results are obtained via two numerical methods, that rest on different theoretical approaches. A generic method is derived from the Dirac-Heisenberg-Wigner (DHW) formalism which entails a modified quantum kinetic equation. We call the numerical solution of this equation the Wigner method. Other types of equations are derived from the DHW formalism as well and numerically solved with the aim to include magnetic fields. In the case of rotating Sauter pulses a completely different numerical method is developed, which is based on a semiclassical approach and therefore called the semiclassical method. A number of parameter studies are conducted to understand pair production in rotating Sauter pulses. The Wigner method and the semiclassical method are compared exhaustively and found to complement each other. This makes it possible to cover the complete range of parameters of the rotating Sauter pulse, which helps to calculate the pair production rates for experiments involving counter-propagating circularly polarized laser light. An interpretation of the pair production spectra is given. Due to the general nature of the Wigner method it is possible to study more general field configurations which include pulses with elliptic polarization, chirp or bichromatic rotating Sauter pulses. Each of these exhibit interesting features, including the dynamically assisted Schwinger effect in bichromatic pulses, which could be useful in planning high-intensity laser experiments.
↳ physics.plasm-phhep-phhep-th12 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.