Tue·Dec 26, 2017Tuesday·December 26, 2017

1. 01*

   Test of an Analytic, Finite, Non-Perturbative, Gauge-Invariant QCD formulation against elastic pp scattering at the ISR energies

   Peter H. Tsang🇺🇸

   A recent QCD formulation that is non-perturbative, finite, gauge-invariant, exact emerged from Schwinger's Generating Functional. A first test of the validity of this formulation is provided here against elastic proton-proton scattering at the Intersecting Storage Rings, ISR, energies. Extension to LHC energies is underway.

   hep-phhep-thAIP Conf.Proc.(2018)·0 citations
2. 02*

   Fate of global symmetries in the Universe: QCD axion, quintessential axion and trans-Planckian inflaton decay-constant

   Jihn E. Kim🇰🇷 · Soonkeon Nam🇰🇷 · Yannis K. Semertzidis

   Pseudoscalars appearing in particle physics are reviewd systematically. From the fundamental point of view at an ultra-violat completed theory, they can be light if they are realized as pseudo-Goldstone bosons of some spontaneously broken global symmetries. The spontaneous breaking scale is parametrized by the decay constant $f$. The global symmetry is defined by the lowest order terms allowed in the effective theory consistent with the gauge symmetry in question. Since any global symmetry is known to be broken at least by quantum gravitational effects, all pseudoscalars should be massive. The mass scale is determined by $f$ and the explicit breaking terms $\Delta V$ in the effective potential and also anomaly terms $\Delta {\Lambda }_G^4$ for some non-Abelian gauge groups $G$. The well-known example by non-Abelian gauge group breaking is the potential for the "invisible" QCD axion, via the Peccei-Quinn symmetry, which constitutes a major part of this review. Even if there is no breaking terms from gauge anomalies, there can be explicit breaking terms $\Delta V$ in the potential in which case the leading term suppressed by $f$ determines the pseudoscalar mass scale. If the breaking term is extremely small and the decay constant is trans-Planckian, the corresponding pseudoscalar can be a candidate for a `quintessential axion'. In general, $(\Delta V{)}^{1/4}$ is considered to be smaller than $f$, and hence the pseudo-Goldstone boson mass scales are considered to be smaller than the decay constants. In such a case, the potential of the pseudo-Goldstone boson at the grand unification scale is sufficiently flat near the top of the potential that it can be a good candidate for an inflationary model, which is known as `natural inflation'. We review all these ideas in the bosonic collective motion framework.

   hep-phInt.J.Mod.Phys.A(2018)·22 citations
3. 03*

   Probing the Dirac or Majorana nature of the Heavy Neutrinos in pure leptonic decays at the LHC

   Carolina Arbelaéz🇨🇱 · Claudio Dib🇨🇱 · Iván Schmidt🇨🇱 · Juan Carlos Vasquez🇨🇱

   We propose a strategy for distinguishing the Dirac / Majorana character of heavy neutrinos with masses below the $W$ boson mass, using purely leptonic decays at the LHC. The strategy makes use of a forward-backward asymmetry of the opposite charge lepton in the $W^{+}\to l^{+}{l}^{+}{l}^{{}^{\prime }-}\nu$ decay. In order to check the experimental feasibility of the model, we show, through a numerical analysis, that in the decay $W^{+}\to e^{+}{e}^{+}{\mu }^{-}\nu$ the two positrons in the final state can be distinguished for different ranges of the heavy neutrino masses. Finally, we estimated the number of events of $W^{+}\to e^{+}{e}^{+}{\mu }^{-}\nu$ for a Dirac and Majorana $N$ neutrino. For an integrated luminosity of 120 fb${}^{-1}$ at LHC RUN II, signals can be found if heavy-to-light neutrino mixings are $|U_{N\mu }{|}^2,|U_{Ne}{|}^2\gtrsim 10^{-6}$.

   hep-phPRD(2018)·31 citations
4. 04*

   QCD Constituent Counting Rules for Neutral Vector Mesons

   Stanley J. Brodsky🇺🇸 · Richard F. Lebed🇺🇸 · Valery E. Lyubovitskij🇩🇪

   QCD constituent counting rules define the scaling behavior of exclusive hadronic scattering and electromagnetic scattering amplitudes at high momentum transfer in terms of the total number of fundamental constituents in the initial and final states participating in the hard subprocess. The scaling laws reflect the twist of the leading Fock state for each hadron and hence the leading operator that creates the composite state from the vacuum. Thus, the constituent counting scaling laws can be used to identify the twist of exotic hadronic candidates such as tetraquarks and pentaquarks. Effective field theories must consistently implement the scaling rules in order to be consistent with the fundamental theory. Here we examine how one can apply constituent counting rules for the exclusive production of one or two neutral vector mesons $V^0$ in $e^{+}{e}^{-}$ annihilation, processes in which the $V^0$ can couple via intermediate photons. In case of a (narrow) real $V^0$, the photon virtuality is fixed to a precise value $s_1=m_{V^0}^2$, in effect treating the $V^0$ as a single fundamental particle. Each real $V^0$ thus contributes to the constituent counting rules with $N_{V_0}=1$. In effect, the leading operator underlying the $V^0$ has twist 1. Thus, in the specific physical case of single or double on-shell $V^0$ production via intermediate photons, the predicted scaling from counting rules coincides with Vector Meson Dominance (VMD), an effective theory that treats $V^0$ as an elementary field. However, the VMD prediction fails in the general case where the $V^0$ is not coupled through an elementary photon field, and then the leading-twist interpolating operator has twist $N_{V_0}=2$. Analogous effects appear in $pp$ scattering processes.

   hep-phPRD(2018)·7 citations
5. 05*

   Photon polarization tensor in circularly polarized Hermite- and Laguerre-Gaussian beams

   Felix Karbstein🇩🇪 · Elena A. Mosman🇷🇺

   We derive analytical expressions for the photon polarization tensor in circularly polarized Hermite- and Laguerre-Gaussian beams, complementing the corresponding results for linearly polarized beams obtained recently. As they are based upon a locally constant field approximation of the one-loop Heisenberg-Euler effective Lagrangian for quantum electrodynamics (QED) in constant fields, our results are generically limited to slowly varying electromagnetic fields, varying on spatial (temporal) scales much larger than the Compton wavelength (time) of the electron.

   hep-phMod.Phys.Lett.A(2018)·3 citations
6. 06*

   Production of single-charm hadrons by quark combination mechanism in $p$-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV

   Hai-hong Li🇨🇳 · Feng-lan Shao🇨🇳 · Jun Song🇨🇳 · Rui-qin Wang🇨🇳

   If QGP-like medium is created in $p$-Pb collisions at extremely high collision energies, charm quarks that move in the medium can hadronize by capturing the co-moving light quark(s) or anti-quark(s) to form the charm hadrons. Using light quark $p_T$ spectra extracted from the experimental data of light-flavor hadrons and a charm quark $p_T$ spectrum that is consistent with perturbative QCD calculations, the central-rapidity data of $p_T$ spectra and the spectrum ratios for $D$ mesons in the low $p_T$ range ($p_T\lesssim 7$ GeV/$c$) in minimum-bias $p$-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV are well described by quark combination mechanism in equal-velocity combination approximation. The ${\Lambda }_c^{+}/D^0$ ratio in quark combination mechanism exhibits the typical increase-peak-decrease behavior as the function of $p_T$, and the shape of the ratio for $p_T\gtrsim 3$ GeV/$c$ is in agreement with the data of ALICE collaboration in central rapidity region $-0.96<y<0.04$ and the preliminary data of LHCb collaboration in forward rapidity region $1.5<y<4.0$. The global production of single-charm baryons is quantified using the data and the possible enhancement (relative to light flavor baryons) is discussed. The $p_T$ spectra of ${\Xi }_c^0$, ${\Omega }_c^0$ in minimum-bias events and those of single-charm hadrons in high-multiplicity event classes are predicted, which serves as the further test of the possible change of the hadronization characteristic for low $p_T$ charm quarks in the small system created in $p$-Pb collisions at LHC energies.

   hep-phPRC(2018)·39 citations
7. 07*

   Probing the $P$-wave charmonium decays of $B_c$ meson

   Zhou Rui🇨🇳

   Motivated by the large number of $B_c$ meson decay modes observed recently by several detectors at the LHC, we present a detailed analysis of the $B_c$ meson decaying to the $P$-wave charmonium states and a light pseudoscalar($P$) or vector ($V$) meson within the framework of perturbative QCD factorization. The $P$-wave charmonium distribution amplitudes are extracted from the $n=2,l=1$ Schr$\ddot{o}$dinger states for a Coulomb potential,which can be taken as the universal nonperturbative objects to analyze the hard exclusive processes with $P$-wave charmonium production. It is found that these decays have large branching ratios of the order of $10^{-5}\sim 10^{-2}$, which seem to be in the reach of future experiments. We also provide predictions for the polarization fractions and relative phases of $B_c\to ({\chi }_{c1},{\chi }_{c2},h_c)V$ decays. It is expected that the longitudinal polarization amplitudes dominate the branching ratios according to the quark helicity analysis, and the magnitudes and phases of parallel polarization amplitude are approximately equal to the perpendicular ones. The obtained results are compared with available experimental data, our previous studies, and numbers from other approaches.

   hep-phhep-exPRD(2018)·26 citations
8. 08*

   $[SU(2){]}^3$ Dark Matter

   Ernest Ma (UC Riverside and HKUST)🇺🇸

   An extra $SU(2{)}_D$ gauge factor is added to the well-known left-right extension of the standard model (SM) of quarks and leptons. Under $SU(2{)}_L\times SU(2{)}_R\times SU(2{)}_D$, two fermion bidoublets $(2,1,2)$ and $(1,2,2)$ are assumed. The resulting model has an automatic dark $U(1)$ symmetry, in the same way that the SM has automatic baryon and lepton $U(1)$ symmetries. Phenomenological implications are discussed, as well as the possible origin of this proposal.

   hep-phPLB(2018)·10 citations
9. 09*

   Bending of light in a Coulomb Gas

   Taekoon Lee🇰🇷

   Photons traveling in a background electromagnetic field may bend via the vacuum polarization effect with the background field. The bending in a Coulomb field by a heavy nucleus is small even at a large atomic number, rendering it difficult to detect experimentally. As an amplifying mechanism of the effect we consider the bending of light traveling in a chamber of Coulomb gas. The Gaussian nature of the bending in the gas increases the total bending angle in proportion to the square root of the photon travel distance. The enhancement can be orders of magnitude over the bending by a single nucleus at a small impact parameter, which may help experimental observation of the Coulombic bending.

   hep-phphysics.opticsPRA(2018)·2 citations
10. 10*

    Muon anomalous magnetic moment in the standard model extension

    S. Aghababaei🇮🇷 · M. Haghighat🇮🇷 · I. Motie🇮🇷

    We consider the standard model extension to explore the anomalous magnetic dipole moment of the muon. In the QED part of the theory for the CP and CPT-even Lorentz parameter $c_{\mu \nu }$, all independent electromagnetic form factors depend on a new scalar as $p^{\prime }.c.p$. Therefore, the form factors, even in zero momentum transfer, can be energy dependent. We examine the magnetic form factor to find such an energy dependent up to the one loop level at the leading order of $c_{\mu \nu }$. We show that at the high energy limit (but low enough to satisfy $p^2/m^2\ll 1$) there is an enhancement on the muon anomalous magnetic moment. For the first time, we find a bound on the $c_{\mu \nu }$ components for the muon as $[c_{TT}+0.35(c_{XX}+c_{YY})+0.28c_{ZZ}]$, which is about $10^{-11}$ in a terrestrial experiment

    hep-phhep-thPRD(2017)·30 citations
11. 11*

    Search for a heavy dark photon at future $e^{+}{e}^{-}$ colliders

    Min He🇨🇳 · Xiao-Gang He🇹🇼 · Cheng-Kai Huang🇹🇼 · Gang Li🇹🇼

    A coupling of a dark photon $A^{\prime }$ from a $U(1{)}_{A^{\prime }}$ with the standard model (SM) particles can be generated through kinetic mixing represented by a parameter $ϵ$. A non-zero $ϵ$ also induces a mixing between $A^{\prime }$ and $Z$ if dark photon mass $m_{A^{\prime }}$ is not zero. This mixing can be large when $m_{A^{\prime }}$ is close to $m_Z$ even if the parameter $ϵ$ is small. Many efforts have been made to constrain the parameter $ϵ$ for a low dark photon mass $m_{A^{\prime }}$ compared with the $Z$ boson mass $m_Z$. We study the search for dark photon in $e^{+}{e}^{-}\to \gamma A^{\prime }\to \gamma {\mu }^{+}{\mu }^{-}$ for a dark photon mass $m_{A^{\prime }}$ as large as kinematically allowed at future $e^{+}{e}^{-}$ colliders. For large $m_{A^{\prime }}$, care should be taken to properly treat possible large mixing between $A^{\prime }$ and $Z$. We obtain sensitivities to the parameter $ϵ$ for a wide range of dark photon mass at planed $e^{+}{e}^{-}$ colliders, such as Circular Electron Positron Collider (CEPC), International Linear Collider (ILC) and Future Circular Collider (FCC-ee). For the dark photon mass $20\text{GeV}\lesssim m_{A^{\prime }}\lesssim 330\text{GeV}$, the $2\sigma$ exclusion limits on the mixing parameter are $ϵ\lesssim 10^{-3}-10^{-2}$. The CEPC with $\sqrt{s}=240\text{GeV}$ and FCC-ee with $\sqrt{s}=160\text{GeV}$ are more sensitive than the constraint from current LHCb measurement once the dark photon mass $m_{A^{\prime }}\gtrsim 50\text{GeV}$. For $m_{A^{\prime }}\gtrsim 220\text{GeV}$, the sensitivity at the FCC-ee with $\sqrt{s}=350\text{GeV}$ and $1.5{\text{ab}}^{-1}$ is better than that at the 13~TeV LHC with $300{\text{fb}}^{-1}$, while the sensitivity at the CEPC with $\sqrt{s}=240\text{GeV}$ and $5{\text{ab}}^{-1}$ can be even better than that at 13~TeV LHC with $3{\text{ab}}^{-1}$ for $m_{A^{\prime }}\gtrsim 180\text{GeV}$.

    hep-phJHEP(2018)·38 citations
12. 12*

    Constraints on the intrinsic charm content of the proton from recent ATLAS data

    V.A. Bednyakov🇷🇺 · S.J. Brodsky🇺🇸 · A.V. Lipatov🇷🇺 · G.I. Lykasov🇷🇺 · M.A. Malyshev🇷🇺 · J. Smiesko🇸🇰 · S. Tokar🇸🇰

    Constraints on the intrinsic charm probability \wccm = P_{{\mathrm{c}\bar \mathrm{c}} / \mathrm{p}} in the proton are obtained for the first time from LHC measurements. The ATLAS Collaboration data for the production of prompt photons, accompanied by a charm-quark jet in pp collisions at $\sqrt{s}=8$ TeV, are used. The upper limit \mbox{$\text{wccm}<1.93$~\%} is obtained at the 68~\% confidence level. This constraint is primarily determined from the theoretical scale and systematical experimental uncertainties. Suggestions for reducing these uncertainties are discussed. The implications of intrinsic heavy quarks in the proton for future studies at the LHC are also discussed.

    hep-phEPJC(2019)·31 citations
13. 13*

    Distribution Amplitudes of Heavy Hadrons: Theory and Applications

    Alexander Ya. Parkhomenko🇷🇺

    The physics of heavy quarks becomes a very reach area of study thanks to an excellent operation of hadron colliders and $B$-factories and exciting results from them. Experimental data obtained allows to get some information about the heavy hadron dynamics. In this case, the models for the heavy hadron wave-functions are required to do theoretical predictions for concrete processes under study. In many cases, the light-cone description is enough to obtain theoretical estimates for heavy hadron decays. A discussion of the wave-functions of the $B$-meson and heavy bottom baryons in terms of the light-cone distribution amplitudes is given in this paper. Simple models for the distribution amplitudes are presented and their scale dependence is discussed. Moments of the distribution amplitudes which are entering the branching fractions of radiative, leptonic and semileptonic $B$-mesons decays are also briefly discussed.

    hep-phProceedings of the Helmholtz Internationa…·1 citation
14. 14*

    Is it possible to study neutrinoless $\beta \beta$ decay by measuring double Gamow-Teller transitions?

    Javier Menéndez🇯🇵 · Noritaka Shimizu🇯🇵 · Kentaro Yako🇯🇵

    Searches of neutrinoless double-beta decay require information on the value of the nuclear matrix elements that rule the process to plan and interpret experiments. At present, however, even the matrix elements obtained with the most reliable many-body approaches do not agree to each other better than a factor two or three. A usual test of the many-body calculations is the comparison to several nuclear observables, but so far no nuclear structure property has been found to show a good correlation to neutrinoless double-beta decay. Here we propose that double charge-exchange experiments can offer a very valuable tool to provide insights on neutrinoless double-beta decay. Double charge-exchange reactions are being currently performed in various laboratories worldwide and aim to find the novel nuclear collectivity given by double Gamow-Teller excitations. Our results suggest a good linear correlation between double Gamow-Teller transitions to the ground state of the final nucleus and neutrinoless double-beta decay nuclear matrix elements. The correlation seems robust across $pf$-shell nuclei.

    ↳ nucl-thhep-exhep-phnucl-exJ.Phys.Conf.Ser.(2018)·8 citations
15. 15*

    Quark deconfinement as supernova explosion engine for massive blue-supergiant stars

    Tobias Fischer🇵🇱 · Niels-Uwe F. Bastian🇵🇱 · Meng-Ru Wu🇹🇼 · Petr Baklanov🇷🇺 · Elena Sorokina🇷🇺 · Sergei Blinnikov🇷🇺 · Stefan Typel🇩🇪 · Thomas Klähn🇺🇸 · David B. Blaschke🇷🇺

    Blue-supergiant stars develop into core-collapse supernovae --- one of the most energetic outbursts in the universe --- when all nuclear burning fuel is exhausted in the stellar core. Previous attempts failed to explain observed explosions of such stars which have a zero-age main sequence mass of 50~M${}_{\odot }$ or more. Here we exploit the largely uncertain state of matter at high density, and connect the modeling of such stellar explosions with a first-order phase transition from nuclear matter to the quark-gluon plasma. The resulting energetic supernova explosions can account for a large variety of lightcurves, from peculiar type II to super-luminous events. The remnants are neutron stars with quark matter core, known as hybrid stars, of about 2~M${}_{\odot }$ at birth. A galactic event of this kind could be observable due to the release of a second neutrino burst. Its observation would confirm such a first-order phase transition at densities relevant for astrophysics.

    ↳ astro-ph.HEhep-phNature Astron.(2018)·161 citations
16. 16*

    Primordial Black Holes and Cosmological Problems

    A.D. Dolgov🇷🇺

    It is argued that the bulk of black holes (BH) in the universe are primordial (PBH). This assertion is strongly supported by the recent astronomical observations, which allow to conclude that supermassive BHs with $M=(10^6-10^9)M_{\odot }$ "work" as seeds for galaxy formation, intermediate mass BHs, $M=(10^3-10^4)M_{\odot }$, do the same job for globular clusters and dwarf galaxies, while black holes of a few solar masses are the constituents of dark matter of the universe. The mechanism of PBH formation, suggested in 1993, which predicted such features of the universe, is described. The model leads to the log-normal mass spectrum of PBHs, which is determined by three constant parameters. With proper adjustment of these parameters the above mentioned features are quantitatively explained. In particular, the calculated density of numerous superheavy BHs in the young universe, $z=5-10$, nicely fits the data. The puzzling properties of the sources of the LIGO-discovered gravitational waves are also naturally explained assuming that these sources are PBHs.

    ↳ astro-ph.COhep-ph3 citations
17. 17*

    Nucleon-to-Delta transition form factors in chiral effective field theory using the complex-mass scheme

    M. Hilt🇩🇪 · T. Bauer🇩🇪 · S. Scherer🇩🇪 · L. Tiator🇩🇪

    We calculate the form factors of the electromagnetic nucleon-to-$\Delta$-resonance transition to third chiral order in manifestly Lorentz-invariant chiral effective field theory. For the purpose of generating a systematic power counting, the complex-mass scheme is applied in combination with the small-scale expansion. We fit the results to available empirical data.

    ↳ nucl-thhep-phnucl-exPRC(2018)·19 citations
18. 18*

    Anomalous transport properties of Dirac and Weyl semimetals

    E. V. Gorbar🇺🇦 · V. A. Miransky🇨🇦 · I. A. Shovkovy🇺🇸 · P. O. Sukhachov🇨🇦

    In this review we discuss a wide range of topological properties of electron quasiparticles in Dirac and Weyl semimetals. Their nontrivial topology is quantified by a monopole-like Berry curvature in the vicinity of Weyl nodes, as well as by the energy and momentum space separations between the nodes. The momentum separation, which is also known as the chiral shift, is one of the key elements of this review. We show that it can be dynamically generated in Dirac materials in a background magnetic field. We also pay a special attention to various forms of interplay between the background electromagnetic fields and the topological characteristics of Dirac and Weyl semimetals. In particular, we discuss their signature features in the transport of the electric and chiral charges, heat, as well as the quantum oscillations associated with the Fermi arc states. The origin of the dissipative transport of the Fermi arc states is critically examined. Finally, a consistent chiral kinetic theory for the description of Weyl semimetals is reviewed and its applications are demonstrated.

    ↳ cond-mat.mes-hallhep-phhep-thLow Temp.Phys.(2018)·47 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.