Fri·Oct 27, 2017Friday·October 27, 2017

1. 01*

   Features of $\pi \Delta$ Photoproduction at High Energies

   J. Nys🇧🇪 · V. Mathieu🇺🇸 · C. Fernández-Ramírez🇲🇽 · A. Jackura🇺🇸 · M. Mikhasenko🇩🇪 · A. Pilloni🇺🇸 · N. Sherrill🇺🇸 · J. Ryckebusch🇧🇪 · A. P. Szczepaniak🇺🇸 · G. Fox (JPAC Collaboration)🇺🇸

   Hybrid/exotic meson spectroscopy searches at Jefferson Lab require the accurate theoretical description of the production mechanism in peripheral photoproduction. We develop a model for $\pi \Delta$ photoproduction at high energies ($5\le E_{\text{lab}}\le 16\text{GeV}$) that incorporates both the absorbed pion and natural-parity cut contributions. We fit the available observables, providing a good description of the energy and angular dependencies of the experimental data. We also provide predictions for the photon beam asymmetry of charged pions at $E_{\text{lab}}=9\text{GeV}$ which is expected to be measured by GlueX and CLAS12 experiments in the near future.

   hep-phPLB(2018)·23 citations
2. 02*

   Melting and freeze-out conditions of hadrons in a thermal medium

   Juan M. Torres-Rincon🇩🇪 · Joerg Aichelin🇫🇷 · Hannah Petersen🇩🇪 · Jean-Bernard Rose🇩🇪 · Joseph Tindall🇬🇧

   We describe two independent frameworks which provide unambiguous determinations of the deconfinement and the decoupling conditions of a relativistic gas at finite temperature. First, we use the Polyakov-Nambu-Jona-Lasinio model to compute meson and baryon masses at finite temperature and determine their melting temperature as a function of their strangeness content. Second, we analyze a simple expanding gas within a Friedmann-Robertson-Walker metric, which admits a well-defined decoupling mechanism. We examine the decoupling time as a function of the particle mass and cross section. We find evidences of an inherent dependence of the hadronization and freeze-out conditions on flavor, and on mass and cross section, respectively.

   hep-phnucl-thEPJ Web Conf.(2018)·0 citations
3. 03*

   Kaon quark distribution functions in the chiral constituent quark model

   Akira Watanabe🇨🇳 · Takahiro Sawada🇺🇸 · Chung Wen Kao🇹🇼

   We investigate the valence $u$ and $\bar{s}$ quark distribution functions of the $K^{+}$ meson, $v^{K(u)}(x,Q^2)$ and $v^{K(\bar{s})}(x,Q^2)$, in the framework of the chiral constituent quark model. We judiciously choose the bare distributions at the initial scale to generate the dressed distributions at the higher scale, considering the meson cloud effects and the QCD evolution, which agree with the phenomenologically satisfactory valence quark distribution of the pion and the experimental data of the ratio $v^{K(u)}(x,Q^2)/v^{\pi (u)}(x,Q^2)$. We show how the meson cloud effects affect the bare distribution functions in detail. We find that a smaller $SU(3)$ flavor symmetry breaking effect is observed, compared with results of the preceding studies based on other approaches.

   hep-phnucl-thPRD(2018)·37 citations
4. 04*

   Neutrino masses, dark matter and leptogenesis with $U(1{)}_{B-L}$ gauge symmetry

   Chao-Qiang Geng🇨🇳 · Hiroshi Okada🇹🇼

   We propose a model with an $U(1{)}_{B-L}$ gauge symmetry, in which small neutrino masses, dark matter and the matter-antimatter asymmetry in the Universe can be simultaneously explained. In particular, the neutrino masses are generated radiatively, while the matter-antimatter asymmetry is led by the leptogenesis mechanism, at TeV scale. We also explore allowed regions of the model parameters and discuss some phenomenological effects including lepton flavor violating processes.

   hep-phPhys.Dark Univ.(2018)·16 citations
5. 05*

   Quarkonium hybrids

   Antonio Vairo🇩🇪

   We discuss the quarkonium hybrid spectrum from the perspective of nonrelativistic effective field theories combined with lattice QCD.

   hep-phPoS(2017)·1 citation
6. 06*

   Unitarity Triangle Analysis in the Standard Model and Beyond

   Cristiano Alpigiani🇺🇸 · Adrian Bevan🇬🇧 · Marcella Bona🇬🇧 · Marco Ciuchini🇮🇹 · Denis Derkach🇷🇺 · Enrico Franco🇮🇹 · Vittorio Lubicz🇮🇹 · Guido Martinelli🇮🇹 · Fabrizio Parodi🇮🇹 · Maurizio Pierini🇨🇭 · Luca Silvestrini🇮🇹 · Viola Sordini🇫🇷 and 3 other authors

   Flavour physics represents a unique test bench for the Standard Model (SM). New analyses performed at the LHC experiments are now providing unprecedented insights into CKM metrology and new evidences for rare decays. The CKM picture can provide very precise SM predictions through global analyses. We present here the results of the latest global SM analysis performed by the UTfit collaboration including all the most updated inputs from experiments, lattice QCD and phenomenological calculations. In addition, the Unitarity Triangle (UT) analysis can be used to constrain the parameter space in possible new physics (NP) scenarios. We update here also the UT analysis beyond the SM by the UTfit collaboration. All of the available experimental and theoretical information on $\Delta F=2$ processes is reinterpreted including a model-independent NP parametrisation. We determine the allowed NP contributions in the kaon, $D$, $B_d$, and $B_s$ sectors and, in various NP scenarios, we translate them into bounds for the NP scale as a function of NP couplings.

   hep-ph26 citations
7. 07*

   Impact of heavy sterile neutrinos on the triple Higgs coupling

   Julien Baglio🇩🇪 · Cedric Weiland🇬🇧

   New physics beyond the Standard Model is required to give mass to the light neutrinos. One of the simplest ideas is to introduce new heavy, gauge singlet fermions that play the role of right-handed neutrinos in a seesaw mechanism. They could have large Yukawa couplings to the Higgs boson, affecting the Higgs couplings and in particular the triple Higgs coupling ${\lambda }_{HHH}^{}$, the measure of which is one of the major goals of the LHC and of future colliders. We present a study of the impact of these heavy neutrinos on ${\lambda }_{HHH}^{}$ at the one-loop level, first in a simplified 3+1 model with one heavy Dirac neutrino and then in the inverse seesaw model. Taking into account all possible experimental constraints, we find that sizeable deviations of the order of 35% are possible, large enough to be detected at future colliders, making the triple Higgs coupling a new, viable observable to constrain neutrino mass models. The effects are generic and are expected in any new physics model including TeV-scale fermions with large Yukawa couplings to the Higgs boson, such as those using the neutrino portal.

   hep-phhep-exPoS(2017)·3 citations
8. 08*

   Collectivity without plasma in hadronic collisions

   Christian Bierlich🇸🇪 · Gösta Gustafson🇸🇪 · Leif Lönnblad🇸🇪

   We present a microscopic model for collective effects in high multiplicity proton--proton collisions, where multiple partonic subcollisions give rise to a dense system of strings. From lattice calculations we know that QCD strings are transversely extended, and we argue that this should result in a transverse pressure and expansion, similar to the flow in a deconfined plasma. The model is implemented in the PYTHIA8 Monte Carlo event generator, and we find that it can qualitatively reproduce the long range azimuthal correlations forming a near-side ridge in high multiplicity proton--proton events at LHC energies.

   hep-phnucl-thPLB(2018)·132 citations
9. 09*

   Hadronic light-by-light scattering in the muon g-2

   Andreas Nyffeler🇩🇪

   We briefly review the current status of the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon. Based on various model calculations in the literature, we obtain the estimate a_{mu}^{HLbL} = (102 \pm 39) x 10^{-11}. Recent developments including more model-independent approaches using dispersion relations and lattice QCD, that could lead to a more reliable estimate, are also discussed.

   hep-phEPJ Web Conf.(2019)·17 citations
10. 10*

    Energy independent scaling of ridge and final state description of high multiplicity p+p collisions at $\sqrt{s}$ = 7 and 13 TeV

    Debojit Sarkar🇮🇳

    An energy independent scaling of the near-side ridge yield at a given multiplicity has been observed by the ATLAS and the CMS collaborations in p+p collisions at s = 7 and 13 TeV. Such a striking feature of the data can be successfully explained by approaches based on initial state momentum space correlation generated due to gluon saturation. In this paper, we try to examine if such a scaling is also an inherent feature of the approaches that employ strong final state interaction in p+p collisions. We find that hydrodynamical modeling of p+p collisions using EPOS 3 shows a violation of such scaling. The current study can, therefore, provide important new insights on the origin of long range azimuthal correlations in high multiplicity p+p collisions at the LHC energies.

    hep-phhep-exPRD(2018)·0 citations
11. 11*

    Investigating the radial flow like effects using identified triggered correlation in pp collisions at $\sqrt{s}$ = 7 TeV

    Debojit Sarkar🇮🇳 · Supriya Das🇮🇳 · Subhasis Chattopadhyay🇮🇳

    An inclusive baryon to meson enhancement with increase in multiplicity has been observed in pp collisions at $\sqrt{s}$= 7 TeV. Such a striking feature of the data can be explained by approaches based on hydrodynamics and multi-parton interactions (MPI) coupled with color reconnection (CR) mechanism. In this paper, we investigate the multiplicity evolution of the charged particle yields associated with pions and protons selected from the intermediate $p_T$ region where the inclusive baryon to meson enhancement has been observed. The study has been peformed using EPOS 3 (hydrodynamics) and PYTHIA 8 (MPI with CR) event generators in pp collisions at 7 TeV. We find that the response of the individual pion and proton triggered correlation towards these two mechanisms is different and can be used to disentangle the effect of one from the other. The current study can, therefore, provide important insights on the origin of radial flow like effects in high multiplicity pp collisions at the LHC energies.

    hep-phhep-ex0 citations
12. 12*

    Cosmological singlet diagnostics of neutrinophilic dark matter

    Ottavia Balducci🇩🇪 · Stefan Hofmann🇩🇪 · Alexis Kassiteridis🇩🇪

    The standard model of particle physics is extended by adding a purely neutrinophilic dark sector. It is shown that theories which accommodate standard model neutrinos as dark radiation are resurrected. Sterile neutrinos bridge the visible and the dark sector and can keep their mutual interactions effective even after the epoch of big bang nucleosythesis. This prolonged contact between dark matter and standard model neutrinos solves the well-known small-scale structure problems of the cosmological standard model. The dark sector presented in this work satisfies all experimental and observational constraints from particle physics and cosmology.

    hep-phastro-ph.COPRD(2018)·13 citations
13. 13*

    Positrons from Primordial Black Hole Microquasars and Gamma-ray Bursts

    Volodymyr Takhistov🇺🇸

    We propose several novel scenarios how capture of small sublunar-mass primordial black holes (PBHs) by compact stars, white dwarfs or neutron stars, can lead to distinct short gamma-ray bursts (sGRBs) as well as microquasars (MQs). In addition to providing new signatures, relativistic jets from these systems will accelerate positrons to high energies. We find that if PBHs constitute a sizable fraction of DM, they can significantly contribute to the excess observed in the positron flux by the Pamela, the AMS-02 and the Fermi-LAT experiments. Our proposal combines the beneficial features of astrophysical sources and dark matter.

    ↳ astro-ph.HEastro-ph.COhep-phPLB(2019)·43 citations
14. 14*

    Influence of final-state radiation on heavy-flavour observables in pp collisions

    L. Vermunt🇳🇱 · J. Aichelin🇫🇷 · P.B. Gossiaux🇫🇷 · K. Werner🇫🇷 · A. Mischke🇳🇱 · B. Guiot🇨🇱 · M. Nahrgang🇫🇷 · T. Pierog🇩🇪

    The influence of final-state radiation (FSR) of heavy quarks on observables in high-energy proton-proton collisions is studied. The transverse momentum correlation of D and Dbar mesons, which have been emitted with an azimuthal difference angle close to 180 degrees, is identified as an observable which is sensitive to the FSR process. We demonstrate this by performing calculations with the EPOS3+HQ model and with the event generator Pythia 6. The initial symmetric pT = pT' correlation for back-to-back pairs does not completely vanish in EPOS3+HQ, neither for the final DDbar pairs nor for the ccbar pairs before hadronisation. Also a significant difference in the shape of the correlation distribution for EPOS3+HQ and Pythia 6 is observed. Therefore, particle correlations in pp data offer the possibility to study several aspects of energy loss in heavy-ion collisions.

    ↳ nucl-thhep-ph3 citations
15. 15*

    Comparing standard distribution and its Tsallis form of transverse momenta in high energy collisions

    Rui-Fang Si🇨🇳 · Hui-Ling Li🇨🇳 · Fu-Hu Liu🇨🇳

    In this paper, the experimental (simulated) transverse momentum spectra of negatively charged pions produced at mid-rapidity in central nucleus-nucleus collisions at the Heavy Ion Synchrotron (SIS), Relativistic Heavy Ion Collider (RHIC), and Large Hadron Collider (LHC) energies obtained by different collaborations are selected by us to investigate, where a few simulated data are taken from the results of FOPI Collaboration who uses the IQMD transport code based on Quantum Molecular Dynamics. A two-component standard distribution and the Tsallis form of standard distribution are used to fit these data in the framework of a multisource thermal model. The excitation functions of main parameters in the two distributions are analyzed. In particular, the effective temperatures extracted from the two-component standard distribution and the Tsallis form of standard distribution are obtained, and the relation between the two types of effective temperatures is studied.

    ↳ nucl-thhep-exhep-phnucl-exAdv.High Energy Phys.(2018)·13 citations
16. 16*

    Inelastic shadowing of secondary pi+-, K+-, p, and bar(p) produced in p+Pb collisions at LHC energy

    G.H. Arakelyan🇦🇲 · C. Merino🇪🇸 · Yu.M. Shabelski🇷🇺 · A.G. Shuvaev🇷🇺

    The inclusive spectra of secondaries produced in soft (minimum-bias) p+Pb collisions at LHC energy are calculated in the frame of the Quark-Gluon String Model, by including the inelastic screening corrections (percolation effects). These effects are expected to be quite large at the very high energies, and they should drive down the spectra in the midrapidity region more than 2 times, at sqrt(sNN)=5 TeV.

    ↳ nucl-thhep-ph0 citations
17. 17*

    Anisotropic Constant-roll Inflation

    Asuka Ito🇯🇵 · Jiro Soda🇯🇵

    We study constant-roll inflation in the presence of a gauge field coupled to an inflaton. By imposing the constant anisotropy condition, we find new exact anisotropic constant-roll inflationary solutions which include anisotropic power-law inflation as a special case. We also numerically show that the new anisotropic solutions are attractors in the phase space.

    ↳ hep-thastro-ph.COgr-qchep-phEPJC(2018)·72 citations
18. 18*

    Study of Lambda polarization at RHIC BES and LHC energies

    Iurii Karpenko🇮🇹 · Francesco Becattini🇮🇹

    In hydrodynamic approach to relativistic heavy ion collisions, hadrons with nonzero spin, produced out of the hydrodynamic medium, can acquire polarization via spin-vorticity thermodynamic coupling mechanism. The hydrodynamical quantity steering the polarization is the thermal vorticity, that is minus the antisymmetric part of the gradient of four-temperature field. Based on this mechanism there have been several calculations in hydrodynamic and non-hydrodynamic models for non-central heavy ion collisions in the RHIC Beam Energy Scan energy range, showing that the amount of polarization of produced $\Lambda$ hyperons ranges from few percents to few permille, and decreases with collision energy. We report on an extension of our existing calculation of global $\Lambda$ polarization in UrQMD+vHLLE model to full RHIC and LHC energies, and discuss the component of polarization along the beam direction, which is the dominant one at high energies.

    ↳ nucl-thhep-phnucl-exEPJ Web Conf.(2018)·5 citations
19. 19*

    Higgs-Yukawa model on the lattice

    David Y.-J. Chu🇹🇼 · Karl Jansen🇩🇪 · Bastian Knippschild🇩🇪 · C.-J. David Lin🇹🇼

    We present results from two projects on lattice calculations for the Higgs-Yukawa model. First we report progress on the search of first-order thermal phase transitions in the presence of a dimension-six operator, with the choices of bare couplings that lead to viable phenomenological predictions. In this project the simulations are performed using overlap fermions to implement the required chiral symmetry. Secondly, our study for applying finite-size scaling techniques near the Gaussian fixed point of the Higgs-Yukawa model is presented. We discuss the analytical formulae for the Higgs Yukawa model and show results for a first numerical study in the pure $O(4)$ scalar sector of the theory.

    ↳ hep-lathep-phEPJ Web Conf.(2018)·7 citations
20. 20*

    Pre-inflationary dynamics in loop quantum cosmology: Power-law potentials

    M. Shahalam🇨🇳 · Manabendra Sharma🇨🇳 · Qiang Wu🇨🇳 · Anzhong Wang🇺🇸

    In this paper, we study the pre-inflationary dynamics for the power-law potential $(V(\varphi )\propto {\varphi }^n)$ with $n<2$ in the framework of loop quantum cosmology. In the case where the kinetic energy of the inflaton dominates at the initial, the evolution of the universe can always be divided into three different phases prior to preheating: {\em bouncing, transition and slow-roll inflation}. During the bouncing phase, the evolution of the expansion factor is independent not only on the initial conditions but also the inflationary potentials, and is given explicitly by an analytical solution. In contrast, for the potential energy dominated initial conditions, this universality is lost. We also obtain total number of e-folds during the slow-roll inflation, whereby physically viable models are identified. In addition, we present phase space analysis for the inflationary potentials under consideration and compare our results with the ones obtained previously for different potentials.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2017)·45 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.