HEP Phenomenology·hep-ph

Mon·Nov 7, 2016Monday·November 7, 2016

16 papers—11 primary·5 cross-listed·reconstructed*

01*
Nuclear parton distributions from the nCTEQ group
A. Kusina🇫🇷
We present the nCTEQ15 global analysis of nuclear parton distribution functions (nPDFs). The main addition to the previous nCTEQ PDFs is the introduction of PDF uncertainties based on the Hessian method. Another important improvement is the inclusion of pion production data from RHIC giving us a handle to constrain gluon PDF. In this presentation we briefly discuss the framework of our analysis and concentrate on the comparison of our results with those of other groups. Additionally we show a first estimate of the impact of the LHC pPb W/Z boson production data on the presented nCTEQ15 PDFs.
hep-phPoS(2016)·1 citation
02*
Contribution to the neutrino magnetic moment coming from 2HDM in presence of magnetic fields
Carlos G. Tarazona🇨🇴 · Rodolfo A. Diaz🇨🇴 · John Moralesa🇨🇴 · Andrés Castillo🇨🇴
The confirmation of the neutrino mass by oscillation phenomena converts the study of the magnetic dipole moment (MDM) of the neutrino, in vacuum and regions where existing external magnetic fields, a topic of particular interest from the theoretical point of view. The MDM has an implicit relation with neutrino masses, and this is a possible benchmark from new physics in the solution of open questions in neutrino physics. Besides we know that this kind of phenomena has significant consequences on cosmology and astrophysics, e.g., under the influence of combined effects of neutrinos in the compact objects formation and evolution of primordials magnetic fields. We calculate and analyze such effects introducing charged Higgs bosons based on the parameter space of several 2HDMs with and without flavor conservation in neutral currents.
hep-phPoS(2017)·2 citations
03*
Sharpening the shape analysis for higher-dimensional operator searches
Sylvain Fichet🇧🇷 · Patricia Rebello Teles🇧🇷 · Alberto Tonero🇧🇷
When the Standard Model is interpreted as the renormalizable sector of a low-energy effective theory, the effects of new physics are encoded into a set of higher dimensional operators. These operators potentially deform the shapes of Standard Model differential distributions of final states observable at colliders. We describe a simple and systematic method to obtain optimal estimations of these deformations when using numerical tools, like Monte Carlo simulations. A crucial aspect of this method is minimization of the estimation uncertainty: we demonstrate how the operator coefficients have to be set in the simulations in order to get optimal results. The uncertainty on the interference term turns out to be the most difficult to control and grows very quickly when the interference is suppressed. We exemplify our method by computing the deformations induced by the $O_{3 W}$ operator in $W^{+} W^{-}$ production at the LHC, and by deriving a bound on $O_{3 W}$ using $8$ TeV CMS data.
hep-phPRD(2017)·10 citations
04*
Simplified Limits on New LHC Resonances
Elizabeth H. Simmons🇺🇸 · R. Sekhar Chivukula🇺🇸 · Pawin Ittisamai🇹🇭 · Kirtimaan Mohan🇺🇸
If an excess potentially heralding new physics is noticed in collider data, it would be useful to be able to compare the data with entire classes of models at once. This talk discusses a method that applies when the new physics corresponds to the production and decay of a single, relatively narrow, s-channel resonance. A simplifed model of the resonance allows us to convert an estimated signal cross section into model-independent bounds on the product of the branching ratios corresponding to production and decay. This quickly reveals whether a given class of models could possibly produce a signal of the observed size. We will describe how to apply our analysis framework to cases of current experimental interest, including resonances decaying to dibosons, diphotons, dileptons, or dijets.
hep-phhep-exEPJ Web Conf.(2017)·0 citations
05*
Double parton scattering in the ultraviolet: addressing the double counting problem
Markus Diehl🇩🇪 · Jonathan R. Gaunt🇳🇱
An important question in the theory of double parton scattering is how to incorporate the possibility of the parton pairs being generated perturbatively via $1 \to 2$ splitting into the theory, whilst avoiding double counting with single parton scattering loop corrections. Here, we describe a consistent approach for solving this problem, which retains the notion of double parton distributions (DPDs) for individual hadrons. Further, we discuss the construction of appropriate model DPDs in our framework, and the use of these to compute the DPS part, presenting DPS 'luminosities' from our model DPDs for a few sample cases.
hep-phPoS(2017)·1 citation
06*
Role of $σ$ exchange in the $γ p \to ϕp$ process and scaling with the $f_{1}$ axial vector meson from a Reggeized model
Byung-Geel Yu🇰🇷 · Hungchong Kim🇰🇷 · Kook-Jin Kong🇰🇷
We investigate the role driven by the scalar meson $σ$ exchange in the photoproduction of the vector meson $ϕ$ (1020) off a proton by using a Reggeized model. Based on the $π^{0} (135) + σ (500) + f_{2} (1270)$ +Pomeron exchanges, we demonstrate that the $σ$ exchange plays the role to reproduce the bump structure at the forward angle in the differential cross section as well as the peaking behavior in the total cross section observed in the CLAS Collaboration. We also discuss the possible observation of the scaled cross section $s^{7} d σ / d t$ at the production angle $θ = 9 0^{\circ}$ from the CLAS data. It is found that the axial vector meson $f_{1} (1285)$ exchange with the trajectory $α_{f_{1}} (t) = 0.028 t + 0.9 \pm 0.2$ arising from the axial anomaly of the QCD vacuum plays the role to clarify the scaling up to 5 GeV.
hep-phnucl-thPRD(2017)·14 citations
07*
Unique Prediction for High-Energy J/\psi Photoproduction: Color Transparency and Saturation
Dieter Schildknecht🇩🇪
Based on the color-dipole picture, we present a successful parameter-free prediction for the recent high-energy $J / ψ$ photoproduction data from the Large Hadron Collider. The experimental data provide empirical evidence for the transition from color transparency to saturation.
hep-phPLB(2017)·4 citations
08*
Radiative bound-state-formation cross-sections for dark matter interacting via a Yukawa potential
Kalliopi Petraki🇫🇷 · Marieke Postma🇳🇱 · Jordy de Vries🇳🇱
We calculate the cross-sections for the radiative formation of bound states by dark matter whose interactions are described in the non-relativistic regime by a Yukawa potential. These cross-sections are important for cosmological and phenomenological studies of dark matter with long-range interactions, residing in a hidden sector, as well as for TeV-scale WIMP dark matter. We provide the leading-order contributions to the cross-sections for the dominant capture processes occurring via emission of a vector or a scalar boson. We offer a detailed inspection of their features, including their velocity dependence within and outside the Coulomb regime, and their resonance structure. For pairs of annihilating particles, we compare bound-state formation with annihilation.
hep-phJHEP(2017)·106 citations
09*
Quark mass effects in quark number susceptibilities
Thorben Graf🇫🇷 · Peter Petreczky🇺🇸
The quark degrees of freedom of the QGP with special focus on mass effects are investigated. A next-to-leading-order perturbation theory approach with quark mass dependence is applied and compared to lattice QCD results.
hep-phhep-latnucl-thJ.Phys.Conf.Ser.(2017)·3 citations
10*
NNLO QCD predictions for single jet inclusive production at the LHC
James Currie🇬🇧 · E.W.N. Glover🇬🇧 · Joao Pires🇩🇪
We report the first calculation of fully differential jet production in all partonic channels at next-to-next-to leading order (NNLO) in perturbative QCD and compare to the available ATLAS 7 TeV data. We discuss the size and shape of the perturbative corrections along with their associated scale variation across a wide range in jet transverse momentum, $p_{T}$ , and rapidity, $y$ . We find significant effects, especially at low $p_{T}$ , and discuss the possible implications for Parton Distribution Function fits.
hep-phhep-exPRL(2017)·210 citations
11*
Portal Connecting Dark Photons and Axions
Kunio Kaneta🇰🇷 · Hye-Sung Lee🇰🇷 · Seokhoon Yun🇰🇷
The dark photon and the axion (or axion-like particle) are popular light particles of the hidden sector. Each of them has been actively searched for through the couplings called the vector portal and the axion portal. We introduce a new portal connecting the dark photon and the axion (axion--photon--dark photon, axion--dark photon--dark photon), which emerges in the presence of the two particles. This dark axion portal is genuinely new couplings, not just from a product of the vector portal and the axion portal, because of the internal structure of these couplings. We present a simple model that realizes the dark axion portal and discuss why it warrants a rich phenomenology.
hep-phPRL(2017)·91 citations
12*
Strongly anomalous non-thermal fixed point in a quenched two-dimensional Bose gas
Markus Karl🇩🇪 · Thomas Gasenzer🇩🇪
Universal scaling behavior in the relaxation dynamics of an isolated two-dimensional Bose gas is studied by means of semi-classical stochastic simulations of the Gross-Pitaevskii model. The system is quenched far out of equilibrium by imprinting vortex defects into an otherwise phase-coherent condensate. A strongly anomalous non-thermal fixed point is identified, associated with a slowed decay of the defects in the case that the dissipative coupling to the thermal background noise is suppressed. At this fixed point, a large anomalous exponent $η ≃ - 3$ and, related to this, a large dynamical exponent $z ≃ 5$ are identified. The corresponding power-law decay is found to be consistent with three-vortex-collision induced loss. The article discusses these aspects of non-thermal fixed points in the context of phase-ordering kinetics and coarsening dynamics, thus relating phenomenological and analytical approaches to classifying far-from-equilibrium scaling dynamics with each other. In particular, a close connection between the anomalous scaling exponent $η$ , introduced in a quantum-field theoretic approach, and conservation-law induced scaling in classical phase-ordering kinetics is revealed. Moreover, the relation to superfluid turbulence as well as to driven stationary systems is discussed.
↳ cond-mat.quant-gascond-mat.stat-mechhep-phphysics.flu-dynNew J.Phys.(2017)·70 citations
13*
Multiquark Hadrons
Stephen Lars Olsen🇰🇷
A number of candidate multiquark hadrons, i.e., particle resonances with substructures that are more complex than the quark-antiquark mesons and three-quark baryons that are prescribed in the textbooks, have recently been observed. In this talk I present: some recent preliminary BESIII results on the near-threshold behavior of sigma(e+e- --> Lambda Lambda-bar) that may or may not be related to multiquark mesons in the light- and strange-quark sectors; results from Belle and LHCb on the electrically charged, charmoniumlike Z(4430)^+ --> pi^+ psi ' resonance that necessarily has a four-quark substructure; and the recent LHCb discovery of the P_c(4380) and P_c(4450) hidden-charm resonances seen as a complex structure in the J/psi p invariant mass distribution for Lambda_b --> K^-J/psi p decays and necessarily have a five-quark substructure and are, therefore, prominent candidates for pentaquark baryons.
↳ hep-exhep-phnucl-exJPS Conf.Proc.(2017)·2 citations
14*
Light-Meson Spectroscopy at COMPASS
Fabian Krinner (for the COMPASS collaboration)🇩🇪
The goal of the COMPASS experiment at CERN is to study the structure and spectroscopy of hadrons. The two-stage spectrometer has large acceptance and covers a wide kinematic range for charged as well as neutral particles allowing to access a wide range of reactions. Light mesons are studied with negative (mostly $π^{-}$ ) and positive ( $p$ , $π^{+}$ ) hadron beams with a momentum of $190 GeV / c$ . The light-meson spectrum is measured in different final states produced in diffractive dissociation reactions with squared four-momentum transfer $t$ to the target between $0.1$ and $1.0 (GeV / c)^{2}$ . The flagship channel is the $π^{-} π^{+} π^{-}$ final state, for which COMPASS has recorded the currently world's largest data sample. These data not only allow us to measure the properties of known resonances with high precision, but also to search for new states. Among these is a new axial-vector signal, the $a_{1} (1420)$ , with unusual properties. The findings are confirmed by the analysis of the $π^{-} π^{0} π^{0}$ final state.
↳ hep-exhep-phEPJ Web Conf.(2017)·3 citations
15*
CPT Symmetry Without Hermiticity
Philip D. Mannheim🇺🇸
In the literature the $C P T$ theorem has only been established for Hamiltonians that are Hermitian. Here we extend the $C P T$ theorem to quantum field theories with non-Hermitian Hamiltonians. Our derivation is a quite minimal one as it requires only the time independent evolution of scalar products and invariance under complex Lorentz transformations. The first of these requirements does not force the Hamiltonian to be Hermitian. Rather, it forces its eigenvalues to either be real or to appear in complex conjugate pairs, forces the eigenvectors of such conjugate pairs to be conjugates of each other, and forces the Hamiltonian to admit of an antilinear symmetry. The latter requirement then forces this antilinear symmetry to be $C P T$ , with Hermiticity of a Hamiltonian thus only being a sufficient condition for $C P T$ symmetry and not a necessary one. $C P T$ symmetry thus has primacy over Hermiticity, and it rather than Hermiticity should be taken as a guiding principle for constructing quantum theories. With conformal gravity being a non-Hermitian theory, our approach allows us to construct a positive, ghost-free norm for the theory, to thereby establish the unitarity of conformal gravity. Since our approach allows for complex energies and decays, our work justifies the use of the $C P T$ theorem in establishing the equality of the lifetimes of unstable particles that are charge conjugates of each other. In the quantum-mechanical limit where charge conjugation is separately conserved, the key results of the $P T$ symmetry program of Bender and collaborators are recovered.
↳ hep-thhep-phquant-phPoS(2016)·0 citations
16*
Effect of the final state interaction of $η^{'} N$ on the $η^{'}$ photoproduction off nucleon
Shuntaro Sakai🇯🇵 · Atsushi Hosaka🇯🇵 · Hideko Nagahiro🇯🇵
We investigate the $η^{'}$ photoproduction off the nucleon with a particular interest in the effect of the final-state interaction (FSI) of the $η^{'}$ meson and nucleon $(η^{'} N)$ based on three-flavor linear sigma model. We find an enhancement in the cross section of the $η^{'}$ photoproduction near the $η^{'} N$ -threshold energy owing to the $η^{'} N$ FSI. With the $η^{'}$ meson at forward angles, the energy dependence near the $η^{'} N$ threshold is well reproduced with the $η^{'} N$ FSI. The cross section at backward angles can also be a good probe to investigate the strength of the $η^{'} N$ interaction.
↳ nucl-thhep-phPRC(2017)·3 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.