Tue·Aug 9, 2016Tuesday·August 9, 2016

1. 01*

   CP asymmetry in heavy Majorana neutrino decays at finite temperature: the hierarchical case

   Simone Biondini🇩🇪 · Nora Brambilla🇩🇪 · Antonio Vairo🇩🇪

   We consider the simplest realization of leptogenesis with one heavy Majorana neutrino species much lighter than the other ones. In this scenario, when the temperature of the early universe is smaller than the lightest Majorana neutrino mass, we compute at first order in the Standard Model couplings and, for each coupling, at leading order in the termperature the CP asymmetry in the decays of the lightest neutrino into leptons and anti-leptons. We perform the calculation using a hierarchy of two effective field theories organized as expansions in the inverse of the heavy-neutrino masses. In the ultimate effective field theory, leading thermal corrections proportional to the Higgs self coupling and the gauge couplings are encoded in one single operator of dimension five, whereas corrections proportional to the top Yukawa coupling are encoded in four operators of dimension seven, which we compute.

   hep-phJHEP(2016)·21 citations
2. 02*

   Split NMSSM with electroweak baryogenesis

   S.V.Demidov🇷🇺 · D.S.Gorbunov🇷🇺 · D.V.Kirpichnikov🇷🇺

   In light of the Higgs boson discovery we reconsider generation of the baryon asymmetry in the non-minimal split Supersymmetry model with an additional singlet superfield in the Higgs sector. We find that successful baryogenesis during the first order electroweak phase transition is possible within phenomenologically viable part of the model parameter space. We discuss several phenomenological consequences of this scenario, namely, predictions for the electric dipole moments of electron and neutron and collider signatures of light charginos and neutralinos.

   hep-phastro-ph.COJHEP(2016)·21 citations
3. 03*

   Contribution of \sigma-meson exchange to elastic lepton-proton scattering

   O. Koshchii🇺🇸 · A. Afanasev🇺🇸

   Lepton mass effects play a decisive role in description of elastic lepton-proton scattering when the beam's energy is comparable to the mass of the lepton. The future MUSE experiment, which is devised to solve the "Proton Radius Puzzle", is going to cover the corresponding kinematic region for a scattering of muons by a proton target. We anticipate that helicity-flip meson exchanges will make a difference in comparison of elastic electron-proton versus muon-proton scattering in MUSE. In this article, we estimate the $\sigma$ meson exchange contribution in the $t$-channel. This contribution, mediated by two-photon coupling of $\sigma$, is calculated to be at most $\sim 0.1\%$ for muons in the kinematics of MUSE and it is about 3 orders in magnitude larger than for electrons because of the lepton-mass difference.

   hep-phPRD(2016)·14 citations
4. 04*

   Absorption of light dark matter in semiconductors

   Yonit Hochberg🇺🇸 · Tongyan Lin🇺🇸 · Kathryn M. Zurek🇺🇸

   Semiconductors are by now well-established targets for direct detection of MeV to GeV dark matter via scattering off electrons. We show that semiconductor targets can also detect significantly lighter dark matter via an absorption process. When the dark matter mass is above the band gap of the semiconductor (around an eV), absorption proceeds by excitation of an electron into the conduction band. Below the band gap, multi-phonon excitations enable absorption of dark matter in the 0.01 eV to eV mass range. Energetic dark matter particles emitted from the sun can also be probed for masses below an eV. We derive the reach for absorption of a relic kinetically mixed dark photon or pseudoscalar in germanium and silicon, and show that existing direct detection results already probe new parameter space. With only a moderate exposure, low-threshold semiconductor target experiments can exceed current astrophysical and terrestrial constraints on sub-keV bosonic dark matter.

   hep-phastro-ph.COPRD(2017)·219 citations
5. 05*

   The Global Higgs as a Signal for Compositeness at the LHC

   Sylvain Fichet🇧🇷 · Gero von Gersdorff🇧🇷 · Eduardo Ponton🇧🇷 · Rogerio Rosenfeld🇧🇷

   The radial excitation of the global symmetry-breaking vacuum in composite Higgs models, called the "global Higgs", has been recently a focus of investigation. In this paper we study the prospects for detecting this composite scalar at the 13 TeV LHC. We compute the global Higgs production rates and estimate the discovery potential of a global Higgs decaying into top quark pairs and into Higgs and electroweak gauge bosons with subsequent hadronic decays. The global Higgs may also decay into fermion resonances such as top partners, providing a new window into compositeness. We show that top partner jets can be effectively unresolved in some regions of the parameter space. Such "boosted top partner" signatures would deserve the development of dedicated substructure analyses.

   hep-phJHEP(2017)·23 citations
6. 06*

   Two-Loop Beam and Soft Functions for Rapidity-Dependent Jet Vetoes

   Shireen Gangal🇩🇪 · Jonathan R. Gaunt🇳🇱 · Maximilian Stahlhofen🇩🇪 · Frank J. Tackmann🇩🇪

   Jet vetoes play an important role in many analyses at the LHC. Traditionally, jet vetoes have been imposed using a restriction on the transverse momentum $p_{Tj}$ of jets. Alternatively, one can also consider jet observables for which $p_{Tj}$ is weighted by a smooth function of the jet rapidity $y_j$ that vanishes as $|y_j|\to \infty$. Such observables are useful as they provide a natural way to impose a tight veto on central jets but a looser one at forward rapidities. We consider two such rapidity-dependent jet veto observables, ${\mathcal{T}}_{Bj}$ and ${\mathcal{T}}_{Cj}$, and compute the required beam and dijet soft functions for the jet-vetoed color-singlet production cross section at two loops. At this order, clustering effects from the jet algorithm become important. The dominant contributions are computed fully analytically while corrections that are subleading in the limit of small jet radii are expressed in terms of finite numerical integrals. Our results enable the full NNLL' resummation and are an important step towards N3LL resummation for cross sections with a ${\mathcal{T}}_{Bj}$ or ${\mathcal{T}}_{Cj}$ jet veto.

   hep-phJHEP(2017)·25 citations
7. 07*

   Exclusions on $Z^{\prime }$ mass and its non-universal couplings in LFV decays

   J. A. Orduz-Ducuara🇲🇽

   This letter presents a phenomenological analysis for the lepton ($l_i^{}$) decaying into $l_j^{}{l}_k^{}{\bar{l}}_k^{},l_j^{}{\pi }^{+}{\pi }^{-}$ considering family non-universal couplings as source of the lepton flavor-violating (LFV) currents and a new neutral gauge boson ($Z^{\prime }$) as mediator in the flavor-changing. The most viable $g_V^{f_i{f}_J}$ and $g_A^{f_i{f}_j}$ couplings are reported as long as derive new bounds for the $M_{Z^{\prime }}^{}$ by using current results from LHC and a phenomenological analysis.

   hep-ph0 citations
8. 08*

   The energy density representation of the strangeness enhancement from p+p to Pb+Pb

   E. Cuautle🇲🇽 · G. Paić🇲🇽

   The energy density is the prime parameter to define the deconfinement of quarks and gluons occurring in collisions of heavy ions. Recently, there is mounting evidence that many observables in proton-proton collisions behave in a manner very similar to the one observed in heavy ions. We present as an additional piece of evidence, a scaling of the strange particle yields as a function of the energy density of the three collision systems: p+p p+Pb and Pb+Pb, using the latest results of the ALICE collaboration.

   hep-phnucl-th13 citations
9. 09*

   Quasielastic production of polarized hyperons in antineutrino--nucleon reactions

   F. Akbar🇮🇳 · M. Rafi Alam🇮🇳 · M. Sajjad Athar🇮🇳 · S. K. Singh🇮🇳

   We have studied the differential cross section as well as the longitudinal and perpendicular components of polarization of final hyperon($\Lambda$,$\Sigma$) produced in the antineutrino induced quasielastic charged current reactions on nucleon and nuclear targets. The nucleon-hyperon transition form factors are determined from the experimental data on quasielastic $(\Delta S=0)$ charged current (anti)neutrino--nucleon scattering and the semileptonic decay of neutron and hyperons assuming G--invariance, T--invariance and SU(3) symmetry. The vector transition form factors are obtained in terms of nucleon electromagnetic form factors for which various parameterizations available in literature have been used. A dipole parameterization for the axial vector form factor and the pseudoscalar transition form factor derived in terms of axial vector form factor assuming PCAC and GT relation extended to strangeness sector have been used in numerical evaluations. The flux averaged cross section and polarization observables corresponding to CERN Gargamelle experiment have been calculated for quasielastic hyperon production and found to be in reasonable agreement with the experimental observations. The numerical results for the flux averaged differential cross section$\frac{d\sigma }{d{Q}^2}$ and longitudinal(perpendicular) polarization $P_L(Q^2)(P_P(Q^2))$ relevant for the antineutrino fluxes of MINER$\nu$A, MicroBooNE, and T2K experiments have been presented. This will be useful in interpreting future experimental results on production cross sections and polarization observables from the experiments on the quasielastic production of hyperons induced by antineutrinos and explore the possibility of determining the axial vector and pseudoscalar form factors in the strangeness sector.

   hep-phPRD(2016)·23 citations
10. 10*

    Higher-Order QCD prediction for dark matter pair associated with a b-jet production at the LHC

    Li Gang🇨🇳 · Yu Si-He🇨🇳 · Song Mao🇨🇳 · Zhang Yu🇨🇳 · Zhou Ya-Jin🇨🇳 · Guo Jian-You🇨🇳

    Dark matter associated visible particle production at high energy colliders provides a unique way to determine the microscopic properties of the dark matter. We investigate a pair of fermionic dark matter particles associated with a b-jet production at the LHC, through a mediator which couples to standard model or dark matter particles via either a vector or axial-vector coupling. The calculation is performed by implementing these simplified models in the FeynRules/MadGraph5 aMC@NLO framework. In our calculation, next-to-leading order QCD corrections and parton-shower effects are considered. We find that this process has a sizeable cross section and the QCD correction can reach more than 2 times than LO results. We also investigate the discovery potential in several benchmark scenarios at the 13TeV LHC.

    hep-ph1 citation
11. 11*

    Connecting Radiative Neutrino Mass, Neutron-Antineutron Oscillation, Proton Decay, and Leptogenesis through Dark Matter

    Pei-Hong Gu🇨🇳 · Ernest Ma🇺🇸 · Utpal Sarkar🇮🇳

    The scotogenic mechanism for radiative neutrino mass is generalized to include neutron-antineutron oscillation as well as proton decay. Dark matter is stabilized by extending the notion of lepton parity to matter parity. Leptogenesis is also a possible byproduct. This framework unifies the description of all these important, but seemingly unrelated, topics in physics beyond the standard model of particle interactions.

    hep-phPRD(2016)·30 citations
12. 12*

    Inflation from Supergravity with Gauged R-symmetry in de Sitter Vacuum

    I. Antoniadis🇫🇷 · A. Chatrabhuti🇹🇭 · H. Isono🇹🇭 · R. Knoops🇨🇭

    We study the cosmology of a recent model of supersymmetry breaking, in the presence of a tuneable positive cosmological constant, based on a gauged shift symmetry of a string modulus that can be identified with the string dilaton. The minimal spectrum of the `hidden' supersymmetry breaking sector consists then of a vector multiplet that gauges the shift symmetry of the dilaton multiplet and when coupled to the MSSM leads to a distinct low energy phenomenology depending on one parameter. Here we study the question if this model can also lead to inflation by identifying the dilaton with the inflaton. We find that this is possible if the Kähler potential is modified by a term that has the form of NS5-brane instantons, leading to an appropriate inflationary plateau around the maximum of the scalar potential, depending on two extra parameters. This model is consistent with present cosmological observations without modifying the low energy particle phenomenology associated to the minimum of the scalar potential.

    hep-phastro-ph.COgr-qchep-thEPJC(2016)·26 citations
13. 13*

    Searching for Dark Absorption with Direct Detection Experiments

    Itay M. Bloch🇮🇱 · Rouven Essig🇺🇸 · Kohsaku Tobioka🇮🇱 · Tomer Volansky🇮🇱 · Tien-Tien Yu🇺🇸

    We consider the absorption by bound electrons of dark matter in the form of dark photons and axion-like particles, as well as of dark photons from the Sun, in current and next-generation direct detection experiments. Experiments sensitive to electron recoils can detect such particles with masses between a few eV to more than 10 keV. For dark photon dark matter, we update a previous bound based on XENON10 data and derive new bounds based on data from XENON100 and CDMSlite. We find these experiments to disfavor previously allowed parameter space. Moreover, we derive sensitivity projections for SuperCDMS at SNOLAB for silicon and germanium targets, as well as for various possible experiments with scintillating targets (cesium iodide, sodium iodide, and gallium arsenide). The projected sensitivity can probe large new regions of parameter space. For axion-like particles, the same current direction detection data improves on previously known direct-detection constraints but does not bound new parameter space beyond known stellar cooling bounds. However, projected sensitivities of the upcoming SuperCDMS SNOLAB using germanium can go beyond these and even probe parameter space consistent with possible hints from the white dwarf luminosity function. We find similar results for dark photons from the sun. For all cases, direct-detection experiments can have unprecedented sensitivity to dark-sector particles.

    hep-phJHEP(2017)·208 citations
14. 14*

    Golden Probe of Electroweak Symmetry Breaking

    Yi Chen🇺🇸 · Joe Lykken🇺🇸 · Maria Spiropulu🇺🇸 · Daniel Stolarski🇨🇦 · Roberto Vega-Morales🇪🇸

    The ratio of the Higgs couplings to $WW$ and $ZZ$ pairs, ${\lambda }_{WZ}$, is a fundamental parameter in electroweak symmetry breaking as well as a measure of the (approximate) custodial symmetry possessed by the gauge boson mass matrix. We show that Higgs decays to four leptons are sensitive, via tree level/1-loop interference effects, to both the magnitude and, in particular, overall sign of ${\lambda }_{WZ}$. Determining this sign requires interference effects, as it is nearly impossible to measure with rate information. Furthermore, simply determining the sign effectively establishes the custodial representation of the Higgs boson. We find that $h\to 4\ell$ ($4\ell \equiv 2e2\mu ,4e,4\mu$) decays have excellent prospects of directly establishing the overall sign at a high luminosity 13 TeV LHC. We also examine the ultimate LHC sensitivity in $h\to 4\ell$ to the magnitude of ${\lambda }_{WZ}$. Our results are independent of other measurements of the Higgs boson couplings and, in particular, largely free of assumptions about the top quark Yukawa couplings which also enter at 1-loop. This makes $h\to 4\ell$ a unique and independent probe of the electroweak symmetry breaking mechanism and custodial symmetry.

    hep-phhep-exPRL(2016)·21 citations
15. 15*

    Strong decays of the charmed mesons $D_1^{\ast }(2680)$, $D_3^{\ast }(2760)$, $D_2^{\ast }(3000)$

    Zhi-Gang Wang🇨🇳

    In this article, we assign the higher charmed mesons $D_1^{\ast }(2680)$, $D_3^{\ast }(2760)$ and $D_2^{\ast }(3000)$ to be the 2S $1^{-}$, 1D $3^{-}$ and 1F $2^{+}$ states, respectively, and study the two-body strong decays to the ground state charmed mesons and light pseudoscalar mesons with the heavy meson effective theory. We obtain the ratios among the strong decays, which can be confronted to the experimental data in the future and shed light on the nature of those higher charmed mesons.

    hep-phCommun.Theor.Phys.(2016)·12 citations
16. 16*

    Conjecture of perturbative QED breakdown at $\alpha {\chi }^{2/3}\gtrsim 1$

    A.M. Fedotov🇷🇺

    Invited talk given at Symposium "Extreme Light Technologies, Science, and Applications" (LPHYS'16, Yerevan, 11-15 July 2016). The old Ritus-Narozhny conjecture of possible breakdown of Intense Field QED perturbation theory for ultrarelativistic particles passing transversely through a strong electromagnetic field is reviewed with a special emphasis on its possible significance for near-future experiments.

    hep-phhep-thphysics.opticsJ.Phys.Conf.Ser.(2017)·94 citations
17. 17*

    Two-loop RGE of a general renormalizable Yang-Mills theory in a renormalization scheme with an explicit UV cutoff

    Piotr H. Chankowski (Warsaw U.)🇵🇱 · Adrian Lewandowski (Potsdam, Max Planck Inst. and Warsaw U.)🇩🇪 · Krzysztof A. Meissner (Warsaw U.)🇵🇱

    We perform a systematic one-loop renormalization of a general renormalizable Yang-Mills theory coupled to scalars and fermions using a regularization scheme with a smooth momentum cutoff $\Lambda$ (implemented through an exponential damping factor). We construct the necessary finite counterterms restoring the BRST invariance of the effective action by analyzing the relevant Slavnov-Taylor identities. We find the relation between the renormalized parameters in our scheme and in the conventional $\overline{\mathrm{MS}}$ scheme which allow us to obtain the explicit two-loop renormalization group equations in our scheme from the known two-loop ones in the $\overline{\mathrm{MS}}$ scheme. We calculate in our scheme the divergences of two-loop vacuum graphs in the presence of a constant scalar background field which allow us to rederive the two-loop beta functions for parameters of the scalar potential. We also prove that consistent application of the proposed regularization leads to counterterms which, together with the original action, combine to a bare action expressed in terms of bare parameters. This, together with treating $\Lambda$ as an intrinsic scale of a hypothetical underlying finite theory of all interactions, offers a possibility of an unconventional solution to the hierarchy problem if no intermediate scales between the electroweak scale and the Planck scale exist.

    hep-phhep-thJHEP(2016)·10 citations
18. 18*

    Saturation in inclusive production beyond leading logarithm accuracy

    Anna M. Stasto🇺🇸 · David Zaslavsky🇨🇳

    We review recent progress on the calculations on the inclusive forward hadron production within the saturation formalism. After introducing the concept of perturbative parton saturation and nonlinear evolution we discuss the formalism for the forward hadron production at high energy in the leading and next-to-leading order. Numerical results are presented and compared with the experimental data on forward hadron production in $dA$ and $pA$. We discuss the problem of the negativity of the NLO cross section at high transverse momenta, study its origin in detail and present possible improvements which include the corrected kinematics and the suitable choice of the rapidity cutoff.

    hep-phInt.J.Mod.Phys.A(2016)·19 citations
19. 19*

    Light gauge boson in rare $K$ decay

    Chuan-Hung Chen🇹🇼 · Takaaki Nomura🇰🇷

    We study the production of a light gauge boson in $K^{-}\to {\pi }^{-}X$ decay, where the associated new charge current is not conserved. It is found that the process can be generated by the tree-level $W$-boson annihilation and loop-induced $s\to dX$. We find that it strongly depends on the $SU(3)$ limit or the unique gauge coupling to the quarks, whether the decay amplitude of $K^{-}\to {\pi }^{-}X$ in the $W$-boson annihilation is suppressed by $m_X^2{ϵ}_X\cdot p_K$; however, no such suppression is found via the loop-induced $s\to dX$. The constraints on the relevant couplings are studied.

    hep-phhep-exPLB(2016)·8 citations
20. 20*

    The muon g-2: retrospective and future

    A. E. Dorokhov🇷🇺 · A. E. Radzhabov🇷🇺 · A. S. Zhevlakov🇷🇺

    Soon, new experiments at FNAL and J-PARC will measure the muon anomalous magnetic moments with better accuracy than before. From theoretical side, the uncertainty of the standard model prediction is dominated by the hadronic contributions. Current status of the experimental data and theoretical calculations are briefly discussed.

    hep-phEPJ Web Conf.(2016)·9 citations
21. 21*

    A Natural origin for the LHCb anomalies

    Eugenio Megias🇩🇪 · Giuliano Panico🇪🇸 · Oriol Pujolas🇪🇸 · Mariano Quiros🇪🇸

    The anomalies recently found by the LHCb collaboration in $B$-meson decays seem to point towards the existence of new physics coupled non-universally to muons and electrons. We show that a beyond-the-Standard-Model dynamics with these features naturally arises in models with a warped extra-dimension that aim to solve the electroweak Hierarchy Problem. The attractiveness of our set-up is the fact that the dynamics responsible for generating the flavor anomalies is automatically present, being provided by the massive Kaluza--Klein excitations of the electroweak gauge bosons. The flavor anomalies can be easily reproduced by assuming that the bottom and muon fields have a sizable amount of compositeness, while the electron is almost elementary. Interestingly enough, this framework correlates the flavor anomalies to a pattern of corrections in the electroweak observables and in flavor-changing processes. In particular the deviations in the bottom and muon couplings to the $Z$-boson and in $\Delta F=2$ flavor-changing observables are predicted to be close to the present experimental bounds, and thus potentially testable in near-future experiments.

    hep-phJHEP(2016)·70 citations
22. 22*

    QCD for collider experiments

    Z.Trócsányi (Debrecen U.)🇭🇺

    These lectures are intended to provide the theoretical basis of describing high-energy particle collisions at a level appropriate to graduate students in experimental high energy physics. They are supposed to be familiar with quantum electrodynamics, the concept of Feynman rules, Feynman graphs and computation of the cross section in quantum field theory.

    hep-phCERN Yellow Report CERN-2015-004, pp.65-1…·0 citations
23. 23*

    Quantum Field Theory and the Electroweak Standard Model

    E.Boos (Moscow State U. & SINP, Moscow)🇷🇺

    The Standard Model is one of the main intellectual achievements for about the last 50 years, a result of many theoretical and experimental studies. In this lecture a brief introduction to the electroweak part of the Standard Model is given. Since the Standard Model is a quantum field theory, some aspects for understanding of quantization of abelian and non-abelian gauge theories are also briefly discussed. It is demonstrated how well the electroweak Standard Model works in describing a large variety of precise experimental measure- ments at lepton and hadron colliders.

    hep-phCERN Yellow Report CERN-2015-004, pp.1-64·4 citations
24. 24*

    An Analytic Approach to Sunset Diagrams in Chiral Perturbation Theory: Theory and Practice

    B. Ananthanarayan🇮🇳 · Johan Bijnens🇸🇪 · Shayan Ghosh🇮🇳 · Aditya Hebbar🇺🇸

    We demonstrate the use of several code implementations of the Mellin-Barnes method available in the public domain to derive analytic expressions for the sunset diagrams that arise in the two-loop contribution to the pion mass and decay constant in three-flavoured chiral perturbation theory. We also provide results for all possible two-mass configurations of the sunset integral, and derive a new one-dimensional integral representation for the one mass sunset integral with arbitrary external momentum. Thoroughly annotated Mathematica notebooks are provided as ancillary files, which may serve as pedagogical supplements to the methods described in this paper.

    hep-phhep-lathep-thEPJA(2016)·10 citations
25. 25*

    Phenomenological MSSM in light of new 13 TeV LHC data

    Kamila Kowalska🇩🇪

    We present the first analysis of the p19MSSM with neutralino dark matter, in light of 13 TeV LHC data with an integrated luminosity of ~14/fb. We recast twelve experimental analyses performed by the ATLAS collaboration and derive exclusion bounds on the parameter space of the model. We find that 25% of the model points can be excluded at 95% C.L. by a combination of the implemented searches. The spectrum allowed after the 13 TeV results are taken into account presents stops heavier than at least 400 GeV, gluinos heavier than at least 790 GeV, and squarks of the first and second generation heavier than at least 440 GeV.

    hep-phEPJC(2016)·27 citations
26. 26*

    The Joint Physics Analysis Center: Recent results

    Cesar Fernandez-Ramirez🇲🇽

    We review some of the recent achievements of the Joint Physics Analysis Center, a theoretical collaboration with ties to experimental collaborations, that aims to provide amplitudes suitable for the analysis of the current and forthcoming experimental data on hadron physics. Since its foundation in 2013, the group is focused on hadron spectroscopy in preparation for the forthcoming high statistics and high precision experimental data from BELLEII, BESIII, CLAS12, COMPASS, GlueX, LHCb and (hopefully) PANDA collaborations. So far, we have developed amplitudes for $\pi N$ scattering, $\bar{K}N$ scattering, pion and $J/\psi$ photoproduction, two kaon photoproduction and three-body decays of light mesons ($\eta$, $\omega$, $\varphi$). The codes for the amplitudes are available to download from the group web page and can be straightforwardly incorporated to the analysis of the experimental data.

    hep-phnucl-thJ.Phys.Conf.Ser.(2016)·1 citation
27. 27*

    Correlations in Double Parton Distributions: Perturbative and Non-Perturbative effects

    Matteo Rinaldi🇮🇹 · Sergio Scopetta🇮🇹 · Marco Claudio Traini🇮🇹 · Vicente Vento🇪🇸

    The correct description of Double Parton Scattering (DPS), which represents a background in several channels for the search of new Physics at the LHC, requires the knowledge of double parton distribution functions (dPDFs). These quantities represent also a novel tool for the study of the three-dimensional nucleon structure, complementary to the possibilities offered by electromagnetic probes. In this paper we analyze dPDFs using Poincaré covariant predictions obtained by using a Light-Front constituent quark model proposed in a recent paper, and QCD evolution. We study to what extent factorized expressions for dPDFs, which neglect, at least in part, two-parton correlations, can be used. We show that they fail in reproducing the calculated dPDFs, in particular in the valence region. Actually measurable processes at existing facilities occur at low longitudinal momenta of the interacting partons; to have contact with these processes we have analyzed correlations between pairs of partons of different kind, finding that, in some cases, they are strongly suppressed at low longitudinal momenta, while for other distributions they can be sizeable. For example, the effect of gluon-gluon correlations can be as large as 20 $\%$. We have shown that these behaviors can be understood in terms of a delicate interference of non-perturbative correlations, generated by the dynamics of the model, and perturbative ones, generated by the model independent evolution procedure. Our analysis shows that at LHC kinematics two-parton correlations can be relevant in DPS, and therefore we address the possibility to study them experimentally.

    hep-phnucl-thJHEP(2016)·44 citations
28. 28*

    Implications of a Electroweak Triplet Scalar Leptoquark on the Ultra-High Energy Neutrino Events at IceCube

    Nicolas Mileo🇦🇷 · Alejandro de la Puente🇨🇦 · Alejandro Szynkman🇦🇷

    We study the production of scalar leptoquarks at IceCube, in particular, a particle transforming as a triplet under the weak interaction. The existence of electroweak-triplet scalars is highly motivated by models of grand unification and also within radiative seesaw models for neutrino mass generation. In our framework, we extend the Standard Model by a single colored electroweak-triplet scalar leptoquark and analyze its implications on the excess of ultra-high energy neutrino events observed by the IceCube collaboration. We consider only couplings between the leptoquark to first generation leptons and quarks and carry out a statistical analysis to determine the parameters that best describe the IceCube data as well as set $95\%$ CL upper bounds. We analyze whether this study is still consistent with most up-to-date LHC data and various low energy observables.

    hep-phJHEP(2016)·16 citations
29. 29*

    The HII Galaxy Hubble Diagram Strongly Favors $R_{\mathrm{h}}=ct$ over $\Lambda$CDM

    Jun-Jie Wei🇨🇳 · Xue-Feng Wu🇨🇳 · Fulvio Melia🇺🇸

    We continue to build support for the proposal to use HII galaxies (HIIGx) and giant extragalactic HII regions (GEHR) as standard candles to construct the Hubble diagram at redshifts beyond the current reach of Type Ia supernovae. Using a sample of 25 high-redshift HIIGx, 107 local HIIGx, and 24 GEHR, we confirm that the correlation between the emission-line luminosity and ionized-gas velocity dispersion is a viable luminosity indicator, and use it to test and compare the standard model $\Lambda$CDM and the $R_{\mathrm{h}}=ct$ Universe by optimizing the parameters in each cosmology using a maximization of the likelihood function. For the flat $\Lambda$CDM model, the best fit is obtained with ${\Omega }_{\mathrm{m}}=0.40_{-0.09}^{+0.09}$. However, statistical tools, such as the Akaike (AIC), Kullback (KIC) and Bayes (BIC) Information Criteria favor $R_{\mathrm{h}}=ct$ over the standard model with a likelihood of $\approx 94.8\%-98.8\%$ versus only $\approx 1.2\%-5.2\%$. For $w$CDM (the version of $\Lambda$CDM with a dark-energy equation of state $w_{\mathrm{de}}\equiv p_{\mathrm{de}}/{\rho }_{\mathrm{de}}$ rather than $w_{\mathrm{de}}=w_{\Lambda }=-1$), a statistically acceptable fit is realized with ${\Omega }_{\mathrm{m}}=0.22_{-0.14}^{+0.16}$ and $w_{\mathrm{de}}=-0.51_{-0.25}^{+0.15}$ which, however, are not fully consistent with their concordance values. In this case, $w$CDM has two more free parameters than $R_{\mathrm{h}}=ct$, and is penalized more heavily by these criteria. We find that $R_{\mathrm{h}}=ct$ is strongly favored over $w$CDM with a likelihood of $\approx 92.9\%-99.6\%$ versus only $0.4\%-7.1\%$. The current HIIGx sample is already large enough for the BIC to rule out $\Lambda$CDM/$w$CDM in favor of $R_{\mathrm{h}}=ct$ at a confidence level approaching $3\sigma$.

    ↳ astro-ph.COastro-ph.GAgr-qchep-phMNRAS(2016)·44 citations
30. 30*

    Strangeness in Neutron Star Cooling

    Yeunhwan Lim🇰🇷 · Chang Ho Hyun🇰🇷 · Chang-Hwan Lee🇰🇷

    We study the thermal evolution of neutron stars in the presence of hyperons or kaons in the core. Our results indicate that the nucleon and hyperon direct Urca processes play crucial roles for the cooling of neutron stars. The presence of hyperons drives fast cooling mechanisms in two ways: 1) it allows the hyperon direct Urca prior to the nucleon direct Urca, 2) and it makes the nucleon direct Urca more feasible by reducing the neutron Fermi momentum. We found that the neutron star equation of state (EOS) with hyperons can be consistent with both mass and temperature observations. We also found that the neutron star EOS with kaon condensation can be consistent with observations, even though the cooling behavior is seldom useful to identify or isolate the effect of kaon condensation.

    ↳ nucl-thastro-ph.HEhep-phJ.Korean Phys.Soc.(2019)·8 citations
31. 31*

    Curvaton scenarios with inflaton decays into curvatons

    Christian T Byrnes🇬🇧 · Marina Cortês🇬🇧 · Andrew R Liddle🇬🇧

    We consider the possible decay of the inflaton into curvaton particles during reheating and analyse its effect on curvaton scenarios. Typical decay curvatons are initially relativistic then become non-relativistic, changing the background history of the Universe. We show that this change to the background is the only way in which observational predictions of the scenario are modified. Moreover, once the required amplitude of perturbations is fixed by observation there are no signatures of such decays in other cosmological observables. The decay curvatons can prevent the Universe from becoming dominated by the curvaton condensate, making it impossible to match observations in parts of parameter space. This constrains the branching ratio of the inflaton to curvaton to be less than of order $0.1$ typically. If the branching ratio is below about $10^{-4}$ it has negligible impact on the model parameter space and can be ignored.

    ↳ astro-ph.COhep-phPRD(2016)·9 citations
32. 32*

    Constraint on the abundance of primordial black holes in dark matter from Planck data

    Lu Chen🇨🇳 · Qing-Guo Huang🇨🇳 · Ke Wang🇨🇳

    We use Planck data released in 2015 to constrain the abundance of primordial black holes (PBHs) in dark matter in two different reionization models (one is the instantaneous reionization and the other is the asymmetric reionization), and significantly improve the upper limits on the abundance of PBHs from WMAP 3-year data by around two orders of magnitude. Furthermore, these new limits imply that the event rates of mergers of PBH binaries (Gpc${}^{-3}$ yr${}^{-1}$) are less than $0.002$ for $M_{\text{pbh}}=30M_{\odot }$, $5$ for $M_{\text{pbh}}=10M_{\odot }$ and $2000$ for $M_{\text{pbh}}=2M_{\odot }$ at $95\%$ confidence level (C.L.), and thus GW150914 seems very unlikely produced by the merger of a PBH binary.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2016)·89 citations
33. 33*

    FCC Based Lepton-Hadron and Photon-Hadron Colliders: Luminosity and Physics

    Y. C. Acar · A. N. Akay · S. Beser · H. Karadeniz · U. Kaya · B. B. Oner · S. Sultansoy

    Construction of future electron-positron colliders (or dedicated electron linac) and muon colliders (or dedicated muon ring) tangential to Future Circular Collider (FCC) will give opportunity to utilize highest energy proton and nucleus beams for lepton-hadron and photon-hadron collisions. Luminosity values of FCC based ep, \mup, eA, \muA, \gammap and \gammaA colliders are estimated. Multi-TeV center of mass energy ep colliders based on the FCC and linear colliders (LC) are considered in detail. Parameters of upgraded versions of the FCC proton beam are determined to optimize luminosity of electron-proton collisions keeping beam-beam effects in mind. Numerical calculations are performed using a currently being developed collision point simulator. It is shown that L_{ep}\sim10^{32}\,cm^{-2}s^{-1} can be achieved with LHeC-like upgrade of the FCC parameters.

    ↳ physics.acc-phhep-exhep-phNucl.Instrum.Meth.A(2017)·73 citations
34. 34*

    Fermion number anomaly with the fluffy mirror fermion

    Ken-ichi Okumura🇯🇵 · Hiroshi Suzuki🇯🇵

    Quite recently, Grabowska and Kaplan presented a 4-dimensional lattice formulation of chiral gauge theories based on the chiral overlap operator. We study this formulation from the perspective of the fermion number anomaly and possible associated phenomenology. A simple argument shows that the consistency of the formulation implies that the fermion with the opposite chirality to the physical one, the "fluffy mirror fermion" or "fluff", suffers from the fermion number anomaly in the same magnitude (with the opposite sign) as the physical fermion. This immediately shows that if at least one of the fluff quarks is massless, the formulation provides a simple viable solution to the strong CP problem. Also, if the fluff interacts with gravity essentially in the same way as the physical fermion, the formulation can realize the asymmetric dark matter scenario.

    ↳ hep-lathep-phhep-thPTEP(2016)·16 citations
35. 35*

    Directed Flow of Charm Quarks as a Witness of the Initial Strong Magnetic Field in Ultra-Relativistic Heavy Ion Collisions

    Santosh K. Das🇮🇹 · Salvatore Plumari🇮🇹 · Sandeep Chatterjee🇮🇳 · Jane Alam🇮🇳 · Francesco Scardina🇮🇹 · Vincenzo Greco🇮🇹

    Ultra-relativistic Heavy-Ion Collision (HIC) generates very strong initial magnetic field ($\vec{B}$) inducing a vorticity in the reaction plane. The high $\vec{B}$ influences the evolution dynamics that is opposed by the large Faraday current due to electric field generated by the time varying $\vec{B}$. We show that the resultant effects entail a significantly large directed flow ($v_1$) of charm quarks (CQs) compared to light quarks due to a combination of several favorable conditions for CQs, mainly: (i) unlike light quarks formation time scale of CQs, ${\tau }_f\simeq 0.1fm/c$ is comparable to the time scale when $\vec{B}$ attains its maximum value and (ii) the kinetic relaxation time of CQs is similar to the QGP lifetime, this helps the CQ to retain the initial kick picked up from the electromagnetic field in the transverse direction. The effect is also odd under charge exchange allowing to distinguish it from the vorticity of the bulk matter due to the initial angular momentum conservation; conjointly thanks to its mass, $M_c>>{\Lambda }_{QCD}$, there should be no mixing with the chiral magnetic dynamics. Hence CQs provide very crucial and independent information on the strength of the magnetic field produced in HIC.

    ↳ nucl-thhep-phPLB(2017)·248 citations
36. 36*

    Bethe-Salpeter wave functions of ${\eta }_c(2S)$ and $\psi (2S)$ states from full lattice QCD

    Kazuki Nochi🇯🇵 · Taichi Kawanai🇩🇪 · Shoichi Sasaki🇯🇵

    We discuss the internal structure of radially excited charmonium mesons based on the equal-time and Coulomb gauge Bethe-Salpeter (BS) amplitudes, which are obtained in lattice QCD. Our simulations are performed with a relativistic heavy-quark action for the charm quark on the 2+1 flavor PACS-CS gauge configurations at the lightest pion mass, $M_{\pi }=156(7)$ MeV. The variational method is applied to the study of optimal charmonium operator for ground and first excited states of $S$-wave charmonia. We successfully calculate the BS wave functions of ${\eta }_c(2S)$ and $\psi (2S)$ states, as well as ${\eta }_c(1S)$ and $J/\psi$ states, and then estimate the root-mean-square radii of both the $1S$ and $2S$ charmonium states. We also examine whether a series of the BS wave functions from the ground state to excited states can be described by a single set of the spin-independent and spin-dependent interquark potentials with a unique quark mass. It is found that the quark kinetic mass and, both the central and spin-spin charmonium potentials, determined from the $2S$ wave functions, fairly agree with the ones from the $1S$ wave functions. This strongly supports the validity of the potential description for the charmonium system, at least, below open-charm threshold.

    ↳ hep-lathep-phPRD(2016)·23 citations
37. 37*

    Dynamics of neutrino lumps in growing neutrino quintessence

    Santiago Casas🇩🇪 · Valeria Pettorino🇩🇪 · Christof Wetterich🇩🇪

    We investigate the formation and dissipation of large scale neutrino structures in cosmologies where the time evolution of dynamical dark energy is stopped by a growing neutrino mass. In models where the coupling between neutrinos and dark energy grows with the value of the scalar cosmon field, the evolution of neutrino lumps depends on the neutrino mass. For small masses the lumps form and dissolve periodically, leaving only a small backreaction of the neutrino structures on the cosmic evolution. This process heats the neutrinos to temperatures much above the photon temperature such that neutrinos acquire again an almost relativistic equation of state. The present equation of state of the combined cosmon-neutrino fluid is very close to -1. In contrast, for larger neutrino masses the lumps become stable. The highly concentrated neutrino structures entail a large backreaction similar to the case of a constant neutrino-cosmon coupling. A present average neutrino mass of around 0.5 eV seems so far compatible with observation. For masses lower than this value, neutrino induced gravitational potentials remain small, making the lumps difficult to detect.

    ↳ astro-ph.COgr-qchep-phPRD(2016)·40 citations
38. 38*

    Neutron star mass limit at $2M_{\odot }$ supports the existence of a CEP

    D. Alvarez-Castillo🇷🇺 · S. Benic🇭🇷 · D. Blaschke🇷🇺 · Sophia Han🇺🇸 · S. Typel🇩🇪

    We point out that the very existence of a "horizontal branch" in the mass-radius characteristics for neutron stars indicates a strong first-order phase transition and thus supports the existence of a critical endpoint (CEP) of first order phase transitions in the QCD phase diagram. This branch would sample a sequence of hybrid stars with quark matter core, leading to the endpoint of stable compact star configurations with the highest possible baryon densities. Since we know of the existence of compact stars with $2M_{\odot }$, this hypothetical branch has to lie in the vicinity of this mass value, if it exists. We report here a correlation between the maximal radius of the horizontal branch and the pressure at the onset of hadron-to-quark matter phase transition which is likely to be a universal quantity of utmost relevance to the upcoming experiments with heavy-ion collisions at NICA and FAIR.

    ↳ nucl-thastro-ph.HEhep-phEPJA(2016)·33 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.