Fri·Feb 16, 2018Friday·February 16, 2018

1. 01*

   Scalar hidden-charm tetraquark states with QCD sum rules

   Zun-Yan Di🇨🇳 · Zhi-Gang Wang🇨🇳 · Jun-Xia Zhang🇨🇳 · Guo-Liang Yu🇨🇳

   In this article, we study the masses and pole residues of the pseudoscalar-diquark-pseudoscalar-antidiquark type and vector-diquark-vector-antidiquark type scalar hidden-charm $cu\bar{c}\bar{d}$ ($cu\bar{c}\bar{s}$) tetraquark states with QCD sum rules by taking into account the contributions of the vacuum condensates up to dimension-10 in the operator product expansion. The predicted masses can be confronted with the experimental data in the future. Possible decays of those tetraquark states are also discussed.

   hep-phCommun.Theor.Phys.(2018)·7 citations
2. 02*

   Quit Using Pseudorapidity, Transverse Energy, and Massless Constituents

   Jason Gallicchio🇺🇸 · Yang-Ting Chien🇺🇸

   Use a massive jet's true-rapidity instead of its pseudorapidity, even for event displays and for determining if a jet is near a calorimeter edge. Use transverse momentum instead of transverse energy since only the former is conserved. Use massive constituents because using massless constituents reduces the jet mass by an amount proportional to the square of the number of hadrons in the jet, and can amount to several GeV. These three recommendations are important for precision measurements when jets are constructed by adding constituent 4-vectors.

   hep-ph11 citations
3. 03*

   Magnetic moments of the lowest-lying singly heavy baryons

   Ghil-Seok Yang🇰🇷 · Hyun-Chul Kim🇰🇷

   A light baryon is viewed as $N_c$ valence quarks bound by meson mean fields in the large $N_c$ limit. In much the same way a singly heavy baryon is regarded as $N_c-1$ valence quarks bound by the same mean fields, which makes it possible to use the properties of light baryons to investigate those of the heavy baryons. A heavy quark being regarded as a static color source in the limit of the infinitely heavy quark mass, the magnetic moments of the heavy baryon are determined entirely by the chiral soliton consisting of a light-quark pair. The magnetic moments of the baryon sextet are obtained by using the parameters fixed in the light-baryon sector. In this mean-field approach, the numerical results of the magnetic moments of the baryon sextet with spin $3/2$ are just 3/2 larger than those with spin $1/2$. The magnetic moments of the bottom baryons are the same as those of the corresponding charmed baryons.

   hep-phhep-exnucl-thPLB(2018)·40 citations
4. 04*

   Extraction of $|V_{cb}|$ from two-body hadronic B decays

   Noriaki Kitazawa🇯🇵 · Kyo-suke Masukawa🇯🇵 · Yuki Sakai🇯🇵

   We propose a method of extracting the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ from two-body hadronic decay processes of $B\to DK$ with precisely determined form factors of $B$ meson semi-leptonic decays. The amplitude $\mathcal{M}({\bar{B}}^0\to D^{+}{K}^{-})$ which does not include the effect of hadronic final state interactions can be theoretically evaluated by using factorization and form factors of semi-leptonic B decays. We can obtain all the amplitudes in an isospin relation $\mathcal{A}(B^{-}\to D^0{K}^{-})=\mathcal{A}({\bar{B}}^0\to D^{+}{K}^{-})+\mathcal{A}({\bar{B}}^0\to D^0{\bar{K}}^0)$ including the effect of hadronic final state interactions as well as $|V_{cb}|$ using the experimental data of branching fractions of these three processes with a truncation of the states which contribute to the hadronic final state interactions. The extracted value of $|V_{cb}|$ is $(37\pm 6)\times 10^{-3}$. The decay processes of $B\to D{K}^{\ast }$ and $B\to D^{\ast }K$ can also be used in the same way and the extracted values of $|V_{cb}|$ are $(41\pm 7)\times 10^{-3}$ and $(42\pm 9)\times 10^{-3}$, respectively. This method becomes possible by virtue of recent precise determinations of the form factors of semi-leptonic B decays. The uncertainties of $|V_{cb}|$ by this method are expected to be reduced by the results of future B-factory experiments and lattice calculations.

   hep-phPTEP(2019)·4 citations
5. 05*

   Documentation of TauSpinner algorithms -- program for simulating spin effects in tau-lepton production at LHC

   T. Przedzinski🇵🇱 · E. Richter-Was🇵🇱 · Z. Was🇵🇱

   The tau-lepton plays an important role in the physics program at the Large Hadron Collider (LHC). It offers a probe in searches for New Physics and to measure parameters of the Standard Model. Spin of tau lepton is an interesting phenomenological quantity for separation of signal from background or in measuring properties of particles. A proper treatment of tau spin effects in the Monte Carlo simulations is important for understanding the detector acceptance as well as for the measurements/use of tau polarization and tau spin correlations. The TauSpinner is a tool to modify tau$spin effects in any sample. Also production matrix elements can be modified with its help. The general principle of TauSpinner algorithm rely on the kinematic of outgoing particles (or jets) only, and to average over all possible initial states accordingly to assumed parton distributions and cross-sections. Incoming on mass-shell parton four-momenta are reconstructed in approximation, but energy-momentum conservation is obeyed. Samples of events featuring tau leptons with their decay products, can be used as an input. The information on the polarization and spin correlations, and production/decay matrix elements is reconstructed from the kinematics of the tau lepton(s) (also nu_tau in case of W-mediated processes) and tau decay products (also jets). No other information is required. By calculating spin (or production/decay matrix element) weights, attributed to each event, it enables evaluation of modifications without regenerating events. Elements of program functionalities together with explanation of the use are given in Appendices. Present publication collect program documentation, previously scattered over several publiications.

   hep-phEPJC(2019)·37 citations
6. 06*

   Shannon entropy and particle decays

   Pedro Carrasco Millan🇪🇸 · M. Angeles Garcia-Ferrero🇪🇸 · Felipe J. Llanes-Estrada🇪🇸 · Ana Porras Riojano🇪🇸 · Esteban M. Sanchez Garcia🇪🇸

   We deploy Shannon's information entropy to the distribution of branching fractions in a particle decay. This serves to quantify how important a given new reported decay channel is, from the point of view of the information that it adds to the already known ones. Because the entropy is additive, one can subdivide the set of channels and discuss, for example, how much information the discovery of a new decay branching would add; or subdivide the decay distribution down to the level of individual quantum states (which can be quickly counted by the phase space). We illustrate the concept with some examples of experimentally known particle decay distributions.

   hep-phhep-exnucl-thNPB(2018)·11 citations
7. 07*

   NNLO classical solution for Lipatov's effective action for reggeized gluons

   S. Bondarenko🇮🇱 · S.S. Pozdnyakov🇮🇱

   We consider the formalism of small-x effective action for reggeized gluons, Gribov (Sov Phys JETP 26:414, 1968), Lipatov (Nucl Phys B 452:369, 1995; Phys Rep 286:131, 1997; Subnucl Ser 49:131, 2013, Int J Mod Phys Conf Ser 39:1560082, 2015; Int J Mod Phys A 31(28/29):1645011, 2016; EPJ Web Conf 125:01010, 2016) and Lipatov et al. (Sov J Nucl Phys 23:338, 1976; Sov Phys JETP 45:199, 1977; Sov J Nucl Phys 28:822, 1978), and, following to the approach developed in Bondarenko et al. (Eur Phys J C 77(8):527, 2017, Eur Phys J C 77(9):630, 2017), calculate the classical gluon field to NNLO precision with fermion loops included. It is demonstrated, that the the self-consistency of the equations of motion in each perturbatie order in the approach is equivalent to the transversality conditions applied to the solutions of the equations in the lower orders, that allows to construct the solutions with the help of some recursive scheme. Applications of the obtained results are also discussed.

   hep-phInt.J.Mod.Phys.A(2019)·5 citations
8. 08*

   Equation for the Nakanishi weight function using the inverse Stieltjes transform

   V.A. Karmanov🇷🇺 · J. Carbonell🇫🇷 · T. Frederico🇧🇷

   The bound state Bethe-Salpeter amplitude was expressed by Nakanishi in terms of a smooth weight function g. By using the generalized Stieltjes transform, we derive an integral equation for the Nakanishi function g for a bound state case. It has the standard form g= Vg, where V is a two-dimensional integral operator. The prescription for obtaining the kernel V starting with the kernel K of the Bethe-Salpeter equation is given.

   hep-phnucl-thFew Body Syst.(2018)·1 citation
9. 09*

   Constraining screened fifth forces with the electron magnetic moment

   Philippe Brax🇫🇷 · Anne-Christine Davis🇬🇧 · Benjamin Elder🇬🇧 · Leong Khim Wong🇬🇧

   Chameleon and symmetron theories serve as archetypal models for how light scalar fields can couple to matter with gravitational strength or greater, yet evade the stringent constraints from classical tests of gravity on Earth and in the Solar System. In this work, we investigate how a precision measurement of the electron magnetic moment places meaningful constraints on both chameleons and symmetrons. Two effects are identified: First, virtual chameleons and symmetrons run in loops to generate quantum corrections to the intrinsic value of the magnetic moment; a common process widely considered in the literature for many scenarios beyond the Standard Model. A second effect, however, is unique to scalar fields that exhibit screening. A scalar bubblelike profile forms inside the experimental vacuum chamber and exerts a fifth force on the electron, leading to a systematic shift in the experimental measurement. In quantifying this latter effect, we present a novel approach that combines analytic arguments and a small number of numerical simulations to solve for the bubblelike profile quickly for a large range of model parameters. Taken together, both effects yield interesting constraints in complementary regions of parameter space. While the constraints we obtain for the chameleon are largely uncompetitive with those in the existing literature, this still represents the tightest constraint achievable yet from an experiment not originally designed to search for fifth forces. We break more ground with the symmetron, for which our results exclude a large and previously unexplored region of parameter space. Central to this achievement are the quantum correction terms, which are able to constrain symmetrons with masses in the range $\mu \in [10^{-3.88},10^8]\text{eV}$, whereas other experiments have hitherto only been sensitive to 1 or 2 orders of magnitude at a time.

   hep-phastro-ph.COphysics.atom-phPRD(2018)·37 citations
10. 10*

    Multiplicity spectra in pp collisions at LHC energies in terms of Gamma and Tsallis distributions

    S. Sharma🇮🇳 · M. Kaur🇮🇳

    In recent years the Tsallis statistics is gaining popularity in describing charged particle produc- tion and their properties, in particular pT spectra and the multiplicities in high energy particle collisions. Motivated by its success, an analysis of the LHC data of proton-proton collisions at ener- gies ranging from 0.9 TeV to 7 TeV in different rapidity windows for charged particle multiplicities has been done. A comparative analysis is performed in terms of the Tsallis distribution, the Gamma distribution and the shifted-Gamma distribution. An interesting observation on the inapplicability of these distributions at sqrt{s}=7 TeV in the lower rapidity windows is intriguing. The non-extensive nature of the Tsallis statistics is studied by determining the entropic index and its energy depen- dence. The analysis is extrapolated to predict the multiplicity distribution at sqrt{s}=14 TeV for one rapidity window, |y| < 1.5 with the Tsallis function.

    hep-phPRD(2018)·5 citations
11. 11*

    Non-thermal Leptogenesis after Majoron Hilltop Inflation

    Stefan Antusch🇨🇭 · Kenneth Marschall🇨🇭

    We analyse non-thermal leptogenesis after models of Majoron hilltop inflation, where the scalar field that provides masses for the right-handed neutrinos and sneutrinos via its vacuum expectation value acts as the inflaton. We discuss different realisations of Majoron inflation models with different hilltop shapes and couplings to the right-handed (s)neutrinos. To study the non-thermally produced baryon asymmetry in these models, we numerically solve the relevant Boltzmann equations. In contrast to previous studies, we include the effects from resonant sneutrino particle production during preheating. We find that these effects can result in an enhancement of the produced baryon asymmetry by more than an order of magnitude. This can significantly change the favoured parameter regions of these models.

    hep-phJCAP(2018)·15 citations
12. 12*

    A Simple No-Scale Model of Modulus Fixing and Inflation

    John Ellis🇬🇧 · Malcolm Fairbairn🇬🇧 · Antonio Enea Romano🇨🇴 · Oscar Zapata🇨🇴

    We construct a no-scale model of inflation with a single modulus whose real and imaginary parts are fixed by simple power-law corrections to the no-scale Kähler potential. Assuming an uplift of the minimum of the effective potential, the model yields a suitable number of e-folds of expansion and values of the tilt in the scalar cosmological density perturbations and of the ratio of tensor and scalar perturbations that are compatible with measurements of the cosmic microwave background radiation.

    hep-phastro-ph.COgr-qchep-thPRD(2018)·2 citations
13. 13*

    Single lepton charge asymmetries in $t\bar{t}$ and $t\bar{t}\gamma$ production at the LHC

    J. A. Aguilar-Saavedra🇪🇸

    We discuss lepton charge asymmetries in $t\bar{t}$ and $t\bar{t}\gamma$ production at the LHC, which can be measured in the semileptonic decay channel $t\bar{t}\to W^{+}b{W}^{-}\bar{b}\to {\ell }^{+}\nu bq{\bar{q}}^{\prime }\bar{b}$ (or the charge conjugate). Considering several variants of a new physics scenario with a light colour octet, it is seen that for $t\bar{t}$ these asymmetries may have a sensitivity competitive with the dilepton asymmetry already measured. For $t\bar{t}\gamma$ the new leptonic asymmetries, as well as the $t\bar{t}$ charge asymmetry, will reach their full potential with the high luminosity LHC upgrade. These asymmetries can pinpoint deviations at the $3\sigma -4\sigma$ level for new physics scenarios where the charge asymmetries already measured in $t\bar{t}$ production agree within $1\sigma$.

    hep-phhep-exEPJC(2018)·7 citations
14. 14*

    Seesaw roadmap to neutrino mass and dark matter

    Salvador Centelles Chuliá🇪🇸 · Rahul Srivastava🇪🇸 · José W. F. Valle🇪🇸

    We describe the many pathways to generate Majorana and Dirac neutrino mass through generalized dimension-5 operators a la Weinberg. The presence of new scalars beyond the Standard Model Higgs doublet implies new possible field contractions, which are required in the case of Dirac neutrinos. We also notice that, in the Dirac neutrino case, the extra symmetries needed to ensure the Dirac nature of neutrinos can also be made responsible for stability of dark matter.

    hep-phPLB(2018)·112 citations
15. 15*

    Charge Symmetry Breaking Effects in Pion and Kaon Structure

    Parada T. P. Hutauruk🇰🇷 · Wolfgang Bentz🇯🇵 · Ian C. Cloët🇺🇸 · Anthony W. Thomas🇦🇺

    Charge symmetry breaking (CSB) effects associated with the $u$ and $d$ quark mass difference are investigated in the quark distribution functions and spacelike electromagnetic form factors of the pion and kaon. We use a confining version of the Nambu--Jona-Lasinio model, where CSB effects at the infrared scale associated with the model are driven by the dressed $u$ and $d$ quark mass ratio, which because of dynamical chiral symmetry breaking is much closer to unity than the associated current quark mass ratio. The pion and kaon are given as bound states of a dressed quark and a dressed antiquark governed by the Bethe-Salpeter equation, and exhibit the properties of Goldstone bosons, with a pion mass difference given by $m_{{\pi }^{+}}^2-m_{{\pi }^0}^2\propto (m_u-m_d{)}^2$ as demanded by dynamical chiral symmetry breaking. We find significant CSB effects for realistic current quark mass ratios ($m_u/m_d\sim 0.5$) in the quark flavor-sector electromagnetic form factors of both the pion and kaon. For example, the difference between the $u$ and $d$ quark contributions to the ${\pi }^{+}$ electromagnetic form factors is about 8\% at a momentum transfer of $Q^2\simeq 10$GeV${}^2$, while the analogous effect for the light quark sector form factors in the $K^{+}$ and $K^0$ is about twice as large. For the Parton distribution functions, we find CSB effects which are considerably smaller than those found in the electromagnetic form factors.

    ↳ nucl-thhep-phPRC(2018)·33 citations
16. 16*

    Dynamically-coupled partial-waves in $\rho \pi$ isospin-2 scattering from lattice QCD

    Antoni J. Woss🇬🇧 · Christopher E. Thomas🇬🇧 · Jozef J. Dudek🇺🇸 · Robert G. Edwards🇺🇸 · David J. Wilson🇮🇪

    We present the first determination of $\rho \pi$ scattering, incorporating dynamically-coupled partial-waves, using lattice QCD, a first-principles numerical approach to QCD. Considering the case of isospin-2 $\rho \pi$, we calculate partial-wave amplitudes with $J\le 3$ and determine the degree of dynamical mixing between the coupled $S$ and $D$-wave channels with $J^P=1^{+}$. The analysis makes use of the relationship between scattering amplitudes and the discrete spectrum of states in the finite volume lattice. Constraints on the scattering amplitudes are provided by over one hundred energy levels computed on two lattice volumes at various overall momenta and in several irreducible representations of the relevant symmetry groups. The spectra follow from variational analyses of matrices of correlations functions computed with large bases of meson-meson operators. Calculations are performed with degenerate light and strange quarks tuned to the physical strange quark mass so that $m_{\pi }\sim 700$ MeV, ensuring that the $\rho$ is stable against strong decay. This work demonstrates the successful application of techniques, opening the door to calculations of scattering processes that incorporate the effects of dynamically-coupled partial-waves, including those involving resonances or bound states.

    ↳ hep-lathep-phJHEP(2018)·70 citations
17. 17*

    Maximum PBH Mass and Primordiality

    P.H. Frampton🇮🇹

    In order to avoid unacceptable $\mu$-distortions inconsistent with observational data on the Cosmic Microwave Background, Primordial Black Holes (PBHs) must be less massive than $10^{12}{M}_{\odot }$, quite closely above the highest black hole mass yet observed. This comparableness leads us to posit that all supermassive black holes originate as PBHs.

    ↳ gr-qcastro-ph.GAhep-phhep-thMod.Phys.Lett.A(2018)·4 citations
18. 18*

    Gravitational waves from vacuum first-order phase transitions: from the envelope to the lattice

    Daniel Cutting🇬🇧 · Mark Hindmarsh🇫🇮 · David J. Weir🇫🇮

    We conduct large scale numerical simulations of gravitational wave production at a first order vacuum phase transition. We find a power law for the gravitational wave power spectrum at high wavenumber which falls off as $k^{-1.5}$ rather than the $k^{-1}$ produced by the envelope approximation. The peak of the power spectrum is shifted to slightly lower wave numbers from that of the envelope approximation. The envelope approximation reproduces our results for the peak power less well, agreeing only to within an order of magnitude. After the bubbles finish colliding the scalar field oscillates around the true vacuum. An additional feature is produced in the UV of the gravitational wave power spectrum, and this continues to grow linearly until the end of our simulation. The additional feature peaks at a length scale close to the bubble wall thickness and is shown to have a negligible contribution to the energy in gravitational waves, providing the scalar field mass is much smaller than the Planck mass.

    ↳ astro-ph.COhep-phPRD(2018)·275 citations
19. 19*

    An Analytical Portrait of Binary Mergers in Hierarchical Triple Systems

    Lisa Randall🇺🇸 · Zhong-Zhi Xianyu🇺🇸

    With better statistics and precision, eccentricity could prove to be a useful tool for understanding the origin and environment of binary black holes. Hierarchical triples in particular, which might be abundant in globular clusters and galactic nuclei, could generate observably large eccentricity at LIGO and future gravitational wave detectors. Measuring the eccentricity distribution accurately could help us probe the background and the formation of the mergers. In this paper we continue our previous investigation and improve our semi-analytical description of the eccentricity distribution of mergers hierarchical triple systems. Our result, which further reduces the reliance on numerical simulations, could be useful for statistically distinguishing different formation channels of observed binary mergers.

    ↳ gr-qcastro-ph.HEhep-phhep-thApJ(2018)·103 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.