Mon·May 15, 2017Monday·May 15, 2017

1. 01*

   Dispersion relations for ${\eta }^{\prime }\to \eta \pi \pi$

   Tobias Isken🇩🇪 · Bastian Kubis🇩🇪 · Sebastian P. Schneider🇩🇪 · Peter Stoffer🇺🇸

   We present a dispersive analysis of the decay amplitude for ${\eta }^{\prime }\to \eta \pi \pi$ that is based on the fundamental principles of analyticity and unitarity. In this framework, final-state interactions are fully taken into account. Our dispersive representation relies only on input for the $\pi \pi$ and $\pi \eta$ scattering phase shifts. Isospin symmetry allows us to describe both the charged and neutral decay channel in terms of the same function. The dispersion relation contains subtraction constants that cannot be fixed by unitarity. We determine these parameters by a fit to Dalitz-plot data from the VES and BES-III experiments. We study the prediction of a low-energy theorem and compare the dispersive fit to variants of chiral perturbation theory.

   hep-phhep-exnucl-exnucl-thEPJC(2017)·63 citations
2. 02*

   Multiparticle production in the large lambda n limit: Realising Higgsplosion in a scalar QFT

   Valentin V. Khoze🇬🇧

   In a scalar theory which we use as a simplified model for the Higgs sector, we adopt the semiclassical formalism of Son for computations of $n$-particle production cross-sections in the high-multiplicity $n\to \infty$ weak-coupling $\lambda \to 0$ regime with the value of $\lambda n$ held fixed and large. The approach relies on the use of singular classical solutions to a certain boundary value problem. In the past this formalism has been successfully used and verified in computations of perturbative multi-particle processes at tree-level, and also at the next-to-leading order level in the small $\lambda n$ expansion near the multi-particle mass threshold. We apply this singular solutions formalism in the regime of ultra-high multiplicities where $\lambda n\gg 1$, and compute the leading positive $\sim n\sqrt{\lambda n}$ contribution to the exponent of the multi-particle rate in this large $\lambda n$ limit. The computation is carried out near the multi-particle mass threshold where the multiplicity $n$ approaches its maximal value allowed by kinematics. This calculation relies on the idea of Gorsky and Voloshin to use a thin wall approximation for the singular solutions that resemble critical bubbles. This approximation is justified in precisely the high-multiplicity $\sqrt{\lambda n}\to \infty$ regime of interest. Based on our results we show that the scalar theory with a spontaneous symmetry breaking used here as a simplified model for the Higgs sector, is very likely to realise the high-energy Higgsplosion phenomenon.

   hep-phhep-thJHEP(2017)·29 citations
3. 03*

   Study on the radiative decays of $h_c$ via intermediate meson loops model

   Qi Wu🇨🇳 · Gang Li🇨🇳 · Yawei Zhang🇨🇳

   Recently, the BESIII Collaboration reported two new decay processes $h_c(1P)\to \gamma \eta$ and $\gamma {\eta }^{\prime }$. Inspired by this measurement, we propose to study the radiative decays of $h_c$ via intermediate charmed meson loops in an effective Lagrangian approach. With the acceptable cutoff parameter range, the calculated branching ratios of $h_c(1P)\to \gamma \eta$ and $\gamma {\eta }^{\prime }$ are orders of $10^{-4}\sim 10^{-3}$ and $10^{-3}\sim 10^{-2}$, respectively. The ratio $R_{h_c}=\mathcal{B}(h_c\to \gamma \eta )/\mathcal{B}(h_c\to \gamma {\eta }^{\prime })$ can reproduce the experimental measurements with the commonly acceptable $\alpha$ range. This ratio provide us some information on the $\eta -{\eta }^{\prime }$ mixing, which may be helpful for us to test SU(3)-flavor symmetries in QCD.

   hep-phEPJC(2017)·5 citations
4. 04*

   High-energy Neutrinos from Multi-body Decaying Dark Matter

   Nagisa Hiroshima🇯🇵 · Ryuichiro Kitano🇯🇵 · Kazunori Kohri🇯🇵 · Kohta Murase🇺🇸

   Since the report of the PeV-TeV neutrinos by the IceCube Collaboration, various particle physics models have been proposed to explain the neutrino spectrum by dark matter particles decaying into neutrinos and other Standard Model particles.In such scenarios, simultaneous $\gamma$-ray emission is commonly expected. Therefore, multi-messenger connections are generally important for the indirect searches of dark matters. The recent development of $\gamma$-ray astronomy puts stringent constraints on the properties of dark matter, especially by observations with the Fermi $\gamma$-ray satellite in the last several years. Motivated by the lack of $\gamma$-ray as well as the shape of the neutrino spectrum observed by IceCube, we discuss a scenario in which the DM is a PeV scale particle which couples strongly to other invisible particles and its decay products do not contain a charged particle. As an example to realize such possibilities, we consider a model of fermionic dark matter that decays into a neutrino and many invisible fermions. The dark matter decay is secluded in the sense that the emitted products are mostly neutrinos and dark fermions. One remarkable feature of this model is the resulting broadband neutrino spectra around the energy scale of the dark matter. We apply this model to multi-PeV dark matter, and discuss possible observable consequences in light of the IceCube data. In particular, this model could account for the large flux at medium energies of $\sim 10-100$ TeV, possibly as well as the second peak at PeV, without violating the stringent $\gamma$-ray constraints from Fermi and air-shower experiments such as CASA-MIA.

   hep-phastro-ph.COastro-ph.HEPRD(2018)·54 citations
5. 05*

   Improving quark flavor separation with forward W and Z production at LHCb

   Juan Rojo🇳🇱

   We quantify the constraints on the flavour separation between the quarks and antiquarks in the proton provided by the recent forward weak gauge boson production data from the LHCb experiment at $\sqrt{s}=7$ and 8 TeV. Performed in the framework of the NNPDF3.1 global analysis, this study highlights the key role that the LHCb W and Z data have in achieving a robust quark flavour separation in the large-x region, including the strange and charm quarks. We demonstrate how the LHCb measurements lead to improved determinations of the the up and down quark PDFs in the region $x\ge 0.1$, with an uncertainty reduction that can be as large as a factor 2. We also show how the LHCb forward measurements severely restrict the size of the fitted charm PDF at large x, imposing stringent constraints on non-perturbative models for the charm content of the nucleon.

   hep-phhep-exPoS(2018)·14 citations
6. 06*

   $H\to e^{+}{e}^{-}$ at CEPC: ISR effect with MadGraph

   Cheng Chen🇨🇳 · Zhenwei Cui🇨🇳 · Gang Li🇨🇳 · Qiang Li🇨🇳 · Manqi Ruan🇨🇳 · Lei Wang🇨🇳 · Qi-shu Yan🇨🇳

   The Circular Electron Positron Collider (CEPC) is a future Higgs factory proposed by the Chinese high energy physics community. It will operate at a center-of-mass energy of 240-250 GeV. The CEPC will accumulate an integrated luminosity of 5 ab${}^{-1}$ in ten years' operation. With GEANT4-based full simulation samples for CEPC, Higgs boson decaying into electron pair is studied at the CEPC. The upper limit of $\mathcal{B}(H\to e^{+}{e}^{-})$ could reach 0.024\% at 95\% confidence level. The signal process is generated by MadGraph, with Initial State Radiation (ISR) implemented, as a first step to adjust MadGraph for a electron positron Collider.

   hep-phhep-ex10 citations
7. 07*

   Gravitino/Axino as Decaying Dark Matter and Cosmological Tensions

   Koichi Hamaguchi🇯🇵 · Kazunori Nakayama🇯🇵 · Yong Tang🇯🇵

   In supersymmetric axion models, if the gravitino or axino is the lightest SUSY particle (LSP), the other is often the next-to-LSP (NLSP). We investigate the cosmology of such a scenario and point out that the lifetime of the NLSP naturally becomes comparable to the present age of the universe in a viable parameter region. This is a well-motivated example of the so-called decaying dark matter model, which is recently considered as an extension of the $\Lambda$CDM model to relax some cosmological tensions.

   hep-phastro-ph.COPLB(2017)·22 citations
8. 08*

   Rapidity Distributions of Hadrons in Proton-Nucleus Collisions

   H.J. Pirner🇩🇪 · B. Kopeliovich🇨🇱

   We study proton-lead collisions with a new model for the Fock states of the incoming proton. The number of collisions which the proton experiences selects the appropriate Fock state of the proton which generates a multiple of pp-like rapidity distributions. We take as input the pp maximum entropy distributions shifting the respective cm-rapidities and reducing the available energies. A comparison with existing data at 5 TeV is made and results for 8 TeV are presented. We also explore the high multiplicity data in this model.

   hep-phnucl-thPRC(2018)·0 citations
9. 09*

   A general framework to diagonalize vector--scalar and axial-vector--pseudoscalar transitions in the effective meson Lagrangian

   Jorge Morais🇵🇹 · Brigitte Hiller🇵🇹 · Alexander A. Osipov🇷🇺

   A new mathematical framework for the diagonalization of the nondiagonal vector--scalar and axial-vector--pseudoscalar mixing in the effective meson Lagrangian is described. This procedure has unexpected connections with the Hadamard product of $n\times n$ matrices describing the couplings, masses, and fields involved. The approach is shown to be much more efficient as compared with the standard methods employed previously. The difference is especially noticeable if the chiral symmetry is broken explicitly. The paper ends with an illustrative application to the chiral model with broken $SU(3{)}_L\times SU(3{)}_R$ symmetry.

   hep-phPLB(2017)·17 citations
10. 10*

    Precise predictions for V+jets dark matter backgrounds

    J. M. Lindert🇬🇧 · S.Pozzorini🇨🇭 · R. Boughezal🇺🇸 · J. M. Campbell🇺🇸 · A. Denner🇩🇪 · S. Dittmaier🇩🇪 · A. Gehrmann-De Ridder🇨🇭 · T. Gehrmann🇨🇭 · N. Glover🇬🇧 · A. Huss🇨🇭 · S. Kallweit🇨🇭 · P. Maierhöfer🇩🇪 and 7 other authors

    High-energy jets recoiling against missing transverse energy (MET) are powerful probes of dark matter at the LHC. Searches based on large MET signatures require a precise control of the $Z(\nu \bar{\nu })+$jet background in the signal region. This can be achieved by taking accurate data in control regions dominated by $Z({\ell }^{+}{\ell }^{-})+$jet, $W(\ell \nu )+$jet and $\gamma +$jet production, and extrapolating to the $Z(\nu \bar{\nu })+$jet background by means of precise theoretical predictions. In this context, recent advances in perturbative calculations open the door to significant sensitivity improvements in dark matter searches. In this spirit, we present a combination of state-of-the art calculations for all relevant $V+$jets processes, including throughout NNLO QCD corrections and NLO electroweak corrections supplemented by Sudakov logarithms at two loops. Predictions at parton level are provided together with detailed recommendations for their usage in experimental analyses based on the reweighting of Monte Carlo samples. Particular attention is devoted to the estimate of theoretical uncertainties in the framework of dark matter searches, where subtle aspects such as correlations across different $V+$jet processes play a key role. The anticipated theoretical uncertainty in the $Z(\nu \bar{\nu })+$jet background is at the few percent level up to the TeV range.

    hep-phhep-exEPJC(2017)·270 citations
11. 11*

    A highly predictive $A_4$ flavour 3-3-1 model with radiative inverse seesaw mechanism

    A. E. Cárcamo Hernández🇨🇱 · H. N. Long🇻🇳

    We build a highly predictive 3-3-1 model, where the field content is extended by including several $SU(3{)}_L$ scalar singlets and six right handed Majorana neutrinos. In our model the $SU(3{)}_C\times SU{\left(3\right)}_L\times U{\left(1\right)}_X$ gauge symmetry is supplemented by the $A_4\times Z_4\times Z_6\times Z_{16}\times Z_{16}^{\prime }$ discrete group, which allows to get a very good description of the low energy fermion flavor data. In the model under consideration, the $A_4\times Z_4\times Z_6\times Z_{16}\times Z_{16}^{\prime }$ discrete group is broken at very high energy scale down to the preserved $Z_2$ discrete symmetry, thus generating the observed pattern of SM fermion masses and mixing angles and allowing the implementation of the loop level inverse seesaw mechanism for the generation of the light active neutrino masses, respectively. The obtained values for the physical observables in the quark sector agree with the experimental data, whereas those ones for the lepton sector also do, only for the case of inverted neutrino mass spectrum. The normal neutrino mass hierarchy scenario of the model is ruled out by the neutrino oscillation experimental data. We find an effective Majorana neutrino mass parameter of neutrinoless double beta decay of meV, a leptonic Dirac CP violating phase of $-81.37^{\circ }$ and a Jarlskog invariant of about $10^{-2}$ for the inverted neutrino mass hierarchy. The preserved $Z_2$ symmetry allows for a stable scalar dark matter candidate.

    hep-phJ.Phys.G(2018)·45 citations
12. 12*

    Conserved charge fluctuations using the $D$-measure in heavy-ion collisions

    D. K. Mishra🇮🇳 · P. K. Netrakanti🇮🇳 · P. Garg🇺🇸

    We study the net-charge fluctuations, $D$-measure variable, in high energy heavy-ion collisions in heavy-ion jet interaction generator (HIJING), ultrarelativistic quantum molecular dynamics (UrQMD) and hadron resonance gas (HRG) models for various center-of-mass energies (\sqsn). The effect of kinematic acceptance and resonance decay, in the pseudorapidity acceptance interval ($\Delta \eta$) and lower transverse momentum ($p_T^{min}$) threshold, on fluctuation measures are discussed. A strong dependence of $D$ with the $\Delta \eta$ in HIJING and UrQMD models is observed as opposed to results obtained from the HRG model. The dissipation of fluctuation signal is estimated by fitting the $D$-measure as a function of the $\Delta \eta$. An extrapolated function for higher $\Delta \eta$ values at lower \sqsn is different from the results obtained from models. Particle species dependence of $D$ and the effect of the $p_T^{min}$ selection threshold are discussed in HIJING and HRG models. The comparison of $D$, at midrapidity, of net-charge fluctuations at various \sqsn obtained from the models with the data from the ALICE experiment is discussed. The results from the present work as a function of $\Delta \eta$ and \sqsn will provide a baseline for comparison to experimental measurements.

    ↳ nucl-thhep-phnucl-exPRC(2017)·6 citations
13. 13*

    Exact Solutions to the Fermion Propagator Schwinger-Dyson Equation in Minkowski space with on-shell Renormalization for Quenched QED

    Shaoyang Jia🇺🇸 · M.R. Pennington🇺🇸

    With the introduction of a spectral representation, the Schwinger-Dyson equation (SDE) for the fermion propagator is formulated in Minkowski space in QED. After imposing the on-shell renormalization conditions, analytic solutions for the fermion propagator spectral functions are obtained in four dimensions with a renormalizable version of the Gauge Technique anzatz for the fermion-photon vertex in the quenched approximation in the Landau gauge. Despite the limitations of this model, having an explicit solution provides a guiding example of the fermion propagator with the correct analytic structure. The Padé approximation for the spectral functions is also investigated.

    ↳ nucl-thhep-phhep-thPRD(2017)·23 citations
14. 14*

    Path description of coordinate-space amplitudes

    Ozan Erdoğan🇺🇸 · George Sterman🇺🇸

    We develop a coordinate version of light-cone-ordered perturbation theory, for general time-ordered products of fields, by carrying out integrals over one light-cone coordinate for each interaction vertex. The resulting expressions depend on the lengths of paths, measured in the same light-cone coordinate. Each path is associated with a denominator equal to a "light-cone deficit", analogous to the "energy deficits" of momentum-space time- or light-cone-ordered perturbation theory. In effect, the role played by intermediate states in momentum space is played by paths between external fields in coordinate space. We derive a class of identities satisfied by coordinate diagrams, from which their imaginary parts can be derived. Using scalar QED as an example, we show how the eikonal approximation arises naturally when the external points in a Green function approach the light cone, and we give applications to products of Wilson lines. Although much of our discussion is directed at massless fields in four dimensions, we extend the formalism to massive fields and dimensional regularization.

    ↳ hep-thhep-phPRD(2017)·7 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.