Wed·Dec 27, 2017Wednesday·December 27, 2017

1. 01*

   Weak Mixing Angle in the Thomson Limit

   Jens Erler🇲🇽 · Rodolfo Ferro-Hernández🇲🇽

   We present a calculation of the weak mixing angle in the $\overline{\mathrm{MS}}$ renormalization scheme which is relevant for experiments performed at very low energies or momentum transfers. We include higher orders in the perturbative QCD expansion, as well as updated phenomenological and theoretical input, and obtain the result ${\sin }^2{\theta }_W(0)=0.23868(5)(2)$ for the reference values ${\alpha }_s(M_Z)=0.1182$ and $m_c(m_c)=1.272$ GeV. The first quoted error is from the current Standard Model evaluation of the mixing angle at the $Z$ boson mass scale. The second error represents the theoretical and parametric uncertainties induced by the evolution to the Thomson limit and is discussed in detail.

   hep-phJHEP(2018)·101 citations
2. 02*

   On the power divergence in quasi gluon distribution function

   Wei Wang🇨🇳 · Shuai Zhao🇨🇳

   Recent perturbative calculation of quasi gluon distribution function at one-loop level shows the existence of extra linear ultraviolet divergences in the cut-off scheme. We employ the auxiliary field approach, and study the renormalization of gluon operators. The non-local gluon operator can mix with new operators under renormalization, and the linear divergences in quasi distribution function can be into the newly introduced operators. After including the mixing, we find the improved quasi gluon distribution functions contain only logarithmic divergences, and thus can be used to extract the gluon distribution in large momentum effective theory.

   hep-phhep-latnucl-thJHEP(2018)·59 citations
3. 03*

   New Insights on Low Energy $\pi N$ Scattering Amplitudes

   Yu-Fei Wang🇨🇳 · De-Liang Yao🇪🇸 · Han-Qing Zheng🇨🇳

   The $S$- and $P$- wave phase shifts of low-energy pion-nucleon scatterings are analysed using Peking University representation, in which they are decomposed into various terms contributing either from poles or branch cuts. We estimate the left-hand cut contributions with the help of tree-level perturbative amplitudes derived in relativistic baryon chiral perturbation theory up to $\mathcal{O}(p^2)$. It is found that in $S_{11}$ and $P_{11}$ channels, contributions from known resonances and cuts are far from enough to saturate experimental phase shift data -- strongly indicating contributions from low lying poles undiscovered before, and we fully explore possible physics behind. On the other side, no serious disagreements are observed in the other channels.

   hep-phnucl-thEPJC(2018)·26 citations
4. 04*

   Tagging a jet from a dark sector with Jet-substructures at colliders

   Myeonghun Park🇰🇷 · Mengchao Zhang🇰🇷

   The phenomenology of dark sector is complicated if dark sector is charged under a confined hidden gauge group. In such kind of model, a dark parton produced at a high energy collider showers and hadronize to a cluster of dark mesons. Dark mesons then decay to visible particles and produce a jet-like signal, which is called "dark jet" in this work. Collider signal of dark jet depends on the property of dark mesons. For example, a finite lifetime of dark meson would provide displaced vertex or displaced track, thus one can use these displaced objects to tag dark jet. However if the lifetime of dark meson is collider-negligible (too short to manifest a displaced vertex), it would be difficult to distinguish a dark jet from SM QCD jets. In this work we propose a new tagging strategy to identify dark jets from QCD backgrounds. This strategy is based on jet-substructure analysis. We study various jet-substructure variables and find out variables with good discrimination ability. Our result shows that by combining multiple jet-substructure variables, one could distinguish dark jets from QCD background, and thus enhance the sensitivity of dark sector search at collider.

   hep-phPRD(2019)·73 citations
5. 05*

   Excited hyperons of the $N=2$ band in the $1/N_c$ expansion

   Fl. Stancu🇧🇪

   The spectrum of excited baryons in the $N$ = 2 band is reanalys9 pagesed in the $1/N_c$ expansion method, with emphasis on hyperons. Predictions are made for the classification of these excited baryons into SU(3) singlets, octets and decuplets.

   hep-phBled Workshops Phys.(2016)·0 citations
6. 06*

   Dynamical study of $S$-wave $\bar{Q}Q\bar{q}q$ system

   You-Chang Yang🇨🇳 · Zhi-Yun Tan🇨🇳 · Hong-Shi Zong🇨🇳 · Jialun Ping🇨🇳

   We perform the energy spectra calculating for the $S$-wave $\bar{Q}Q\bar{q}q$ (where $Q=c,b$ and $q=u,d,s$) system within two constituent quark models. The bound states of $B^{\ast }{\bar{B}}^{\ast }$ with $I(J^{PC})=1(0^{++}),1(1^{+-}),0(2^{++})$ and $B{\bar{B}}^{\ast }$ with isospin $I=1$, or $0$ are obtained in color-singlet-singlet channel. If considering the coupling of color channels, apart from the deep bound states appear in $[b\bar{q}{]}^{(\ast )}[q\bar{b}{]}^{(\ast )}$ scenario, a bound state $[c\bar{q}{]}^{\ast }[q\bar{c}{]}^{\ast }$ with $I(J^{PC})=1(0^{++})$ is also formed. The $B{\bar{B}}^{\ast }$ and the $B^{\ast }{\bar{B}}^{\ast }$ with quantum number $1(1^{+-})$ are well candidates for $Z_b^{\pm }(10610)$ and $Z_b^{\pm }(10650)$ reported by Belle collaboration respectively, while the $B{\bar{B}}^{\ast }$ with isospin $0$ can be interpret as a candidate for $Z_b^0(10610)$. A bound state $[c\bar{q}{]}^{\ast }[q\bar{c}{]}^{\ast }$ with $I(J^{PC})=1(0^{++})$ is comparable with $Z_c^{+}(4025)$ announced by BES.

   hep-phFew Body Syst.(2019)·9 citations
7. 07*

   Effects of composite pions on the chiral condensate within the PNJL model at finite temperature

   D. Blaschke🇷🇺 · A. Dubinin🇵🇱 · D. Ebert🇩🇪 · A. V. Friesen🇷🇺

   We investigate the effect of composite pions on the behaviour of the chiral condensate at finite temperature within the Polyakov-loop improved NJL model. To this end we treat quark-antiquark correlations in the pion channel (bound states and scattering continuum) within a Beth-Uhlenbeck approach that uses medium-dependent phase shifts. A striking medium effect is the Mott transition which occurs when the binding energy vanishes and the discrete pion bound state merges the continuum. This transition is triggered by the lowering of the continuum edge due to the chiral restoration transition. This in turn also entails a modification of the Polyakov-loop so that the SU(3) center symmetry gets broken at finite temperature and dynamical quarks (and gluons) appear in the system, taking over the role of the dominant degrees of freedom from the pions. At low temperatures our model reproduces the chiral perturbation theory result for the chiral condensate while at high temperatures the PNJL model result is recovered. The new aspect of the current work is a consistent treatment of the chiral restoration transition region within the Beth-Uhlenbeck approach on the basis of mesonic phase shifts for the treatment of the correlations.

   hep-phnucl-thPhys.Part.Nucl.Lett.(2018)·8 citations
8. 08*

   Domain-Wall Standard Model in non-compact 5D and LHC phenomenology

   Nobuchika Okada🇺🇸 · Digesh Raut🇺🇸 · Desmond Villalba🇺🇸

   We propose a framework to construct "Domain-Wall Standard Model" in a non compact 5-dimensional space-time, where all the Standard Model (SM) fields are localized in certain domains of the 5th dimension and the SM is realized as a 4-dimensional effective theory without any compactification for the 5th dimension. In this context, we investigate the collider phenomenology of the Kaluza-Klein (KK) modes of the SM gauge bosons and the current constraints from the search for a new gauge boson resonance at the LHC Run-2. The couplings of the SM fermions with the KK-mode gauge bosons depend on the configuration of the SM fermions in the 5-dimensional bulk. This "geometry" of the model can be tested at the future Large Hadron Collider experiment, once a KK-mode of the SM gauge boson is discovered.

   hep-phhep-thMod.Phys.Lett.A(2019)·10 citations
9. 09*

   A "Vector-like chiral" fourth family to explain muon anomalies

   Stuart Raby🇺🇸 · Andreas Trautner🇩🇪

   The Standard Model (SM) is amended by one generation of quarks and leptons which are vector-like (VL) under the SM gauge group but chiral with respect to a new $\mathrm{U}(1{)}_{3-4}$ gauge symmetry. We show that this model can simultaneously explain the deviation of the muon $g-2$ as well as the observed anomalies in $b\to s{\mu }^{+}{\mu }^{-}$ transitions without conflicting with the data on Higgs decays, lepton flavor violation, or $B_s-{\bar{B}}_s$ mixing. The model is string theory motivated and GUT compatible, i.e. UV complete, and fits the data predicting VL quarks, leptons and a massive $Z^{\prime }$ at the $\mathrm{TeV}$ scale, as well as $\tau \to 3\mu$ and $\tau \to \mu \gamma$ within reach of future experiments. The Higgs couplings to SM generations are automatically aligned in flavor space.

   hep-phPRD(2018)·70 citations
10. 10*

    Spinning particles, axion radiation, and the classical double copy

    Walter D. Goldberger🇺🇸 · Jingping Li🇺🇸 · Siddharth G. Prabhu🇺🇸

    We extend the perturbative double copy between radiating classical sources in gauge theory and gravity to the case of spinning particles. We construct, to linear order in spins, perturbative radiating solutions to the classical Yang-Mills equations sourced by a set of interacting color charges with chromomagnetic dipole spin couplings. Using a color-to-kinematics replacement rule proposed earlier by one of the authors, these solutions map onto radiation in a theory of interacting particles coupled to massless fields that include the graviton, a scalar (dilaton) $\varphi$ and the Kalb-Ramond axion field $B_{\mu \nu }$. Consistency of the double copy imposes constraints on the parameters of the theory on both the gauge and gravity sides of the correspondence. In particular, the color charges carry a chromomagnetic interaction which, in $d=4$, corresponds to a gyromagnetic ratio equal to Dirac's value $g=2$. The color-to-kinematics map implies that on the gravity side, the bulk theory of the fields $(\varphi ,g_{\mu \nu },B_{\mu \nu })$ has interactions which match those of $d$-dimensional `string gravity,' as is the case both in the BCJ double copy of pure gauge theory scattering amplitudes and the KLT relations between the tree-level $S$-matrix elements of open and closed string theory.

    ↳ hep-thgr-qchep-phPRD(2018)·158 citations
11. 11*

    $B$- and $D$-meson leptonic decay constants from four-flavor lattice QCD

    A. Bazavov🇺🇸 · C. Bernard🇺🇸 · N. Brown🇺🇸 · C. DeTar🇺🇸 · A.X. El-Khadra🇺🇸 · E. Gámiz🇪🇸 · Steven Gottlieb🇺🇸 · U.M. Heller🇺🇸 · J. Komijani🇩🇪 · A.S. Kronfeld🇺🇸 · J. Laiho🇺🇸 · P.B. Mackenzie🇺🇸 and 5 other authors

    We calculate the leptonic decay constants of heavy-light pseudoscalar mesons with charm and bottom quarks in lattice quantum chromodynamics on four-flavor QCD gauge-field configurations with dynamical $u$, $d$, $s$, and $c$ quarks. We analyze over twenty isospin-symmetric ensembles with six lattice spacings down to $a\approx 0.03$~fm and several values of the light-quark mass down to the physical value $\frac{1}{2}(m_u+m_d)$. We employ the highly-improved staggered-quark (HISQ) action for the sea and valence quarks; on the finest lattice spacings, discretization errors are sufficiently small that we can calculate the $B$-meson decay constants with the HISQ action for the first time directly at the physical $b$-quark mass. We obtain the most precise determinations to-date of the $D$- and $B$-meson decay constants and their ratios, $f_{D^{+}}=212.7(0.6)$~MeV, $f_{D_s}=249.9(0.4)$~MeV, $f_{D_s}/f_{D^{+}}=1.1749(16)$, $f_{B^{+}}=189.4(1.4)$~MeV, $f_{B_s}=230.7(1.3)$~MeV, $f_{B_s}/f_{B^{+}}=1.2180(47)$, where the errors include statistical and all systematic uncertainties. Our results for the $B$-meson decay constants are three times more precise than the previous best lattice-QCD calculations, and bring the QCD errors in the Standard-Model predictions for the rare leptonic decays $\overline{\mathcal{B}}(B_s\to {\mu }^{+}{\mu }^{-})=3.64(11)\times 10^{-9}$, $\overline{\mathcal{B}}(B^0\to {\mu }^{+}{\mu }^{-})=1.00(3)\times 10^{-10}$, and $\overline{\mathcal{B}}(B^0\to {\mu }^{+}{\mu }^{-})/\overline{\mathcal{B}}(B_s\to {\mu }^{+}{\mu }^{-})=0.0273(9)$ to well below other sources of uncertainty. As a byproduct of our analysis, we also update our previously published results for the light-quark-mass ratios and the scale-setting quantities $f_{p4s}$, $M_{p4s}$, and $R_{p4s}$. We obtain the most precise lattice-QCD determination to date of the ratio $f_{K^{+}}/f_{{\pi }^{+}}=1.1950{(}_{-23}^{+16})$~MeV.

    ↳ hep-lathep-phPRD(2018)·369 citations
12. 12*

    Emergent Dark Matter in Late Time Universe on Holographic Screen

    Rong-Gen Cai🇨🇳 · Sichun Sun🇹🇼 · Yun-Long Zhang🇰🇷

    We discuss a scenario that the dark matter in late time universe emerges as part of the holographic stress-energy tensor on the hypersurface in higher dimensional flat spacetime. Firstly we construct a toy model with a de Sitter hypersurface as the holographic screen in the flat bulk. After adding the baryonic matter on the screen, we assume that both of the dark matter and dark energy can be described by the Brown-York stress-energy tensor. From the Hamiltonian constraint equation in the flat bulk, we find an interesting relation between the dark matter and baryonic matter's energy density parameters, by comparing with the Lambda cold dark matter parameterization. We further compare this holographic embedding of emergent dark matter with traditional braneworld scenario and present an alternative interpretation as the holographic universe. It can be reduced to our toy constraint in the late time universe, with the new parameterization of the Friedmann equation. We also comment on the possible connection with Verlinde's emergent gravity, where the dark matter is treated as the elastic response of the baryonic matter on the de Sitter spacetime background. We show that from the holographic de Sitter model with elasticity, the Tully-Fisher relation and the dark matter distribution in the galaxy scale can be derived.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2018)·13 citations
13. 13*

    Conformal Frame dependence on Cosmological Observations in Scalar-Tensor Theories of Gravity

    Young-Hwan Hyun🇰🇷 · Yoonbai Kim🇰🇷 · Seokcheon Lee🇰🇷

    Cosmological observations provide more accurate values both for background evolution of the Universe and for the structure formation. These values are given by the so-called dark energy equation of state, $\omega$ and the growth index parameter, $\gamma$. From these observed parameters, one can reconstruct the model functions in scalar tensor gravity theories. However, there is a long standing debate about the (in)equality between conformally transformed frames in scalar tensor gravity models. We show that cosmological observables are frame dependent when they are described by frame independent parameter, redshift. Thus, if the cosmological observables are interpreted in one frame, then all of the observables should also be interpreted in that frame. This explicitly shows the conformal inequality of cosmological observables. Also, our method provides the model independent analysis for STG models about various observables in both frames.

    ↳ gr-qchep-phJ.Korean Phys.Soc.(2019)·3 citations
14. 14*

    Dynamics of entanglement in expanding quantum fields

    Jürgen Berges🇩🇪 · Stefan Floerchinger🇩🇪 · Raju Venugopalan🇺🇸

    We develop a novel real-time approach to computing the entanglement between spatial regions for Gaussian states in quantum field theory. The entanglement entropy is characterized in terms of local correlation functions on space-like Cauchy hypersurfaces. The framework is applied to explore an expanding light cone geometry in the particular case of the Schwinger model for quantum electrodynamics in 1+1 space-time dimensions. We observe that the entanglement entropy becomes extensive in rapidity at early times and that the corresponding local reduced density matrix is a thermal density matrix for excitations around a coherent field with a time dependent temperature. Since the Schwinger model successfully describes many features of multiparticle production in $e^{+}{e}^{-}$ collisions, our results provide an attractive explanation in this framework for the apparent thermal nature of multiparticle production even in the absence of significant final state scattering.

    ↳ hep-thhep-phnucl-thJHEP(2018)·108 citations
15. 15*

    Complete sets of logarithmic vector fields for integration-by-parts identities of Feynman integrals

    Janko Boehm🇩🇪 · Alessandro Georgoudis🇸🇪 · Kasper J. Larsen🇬🇧 · Mathias Schulze🇩🇪 · Yang Zhang🇨🇭

    Integration-by-parts identities between loop integrals arise from the vanishing integration of total derivatives in dimensional regularization. Generic choices of total derivatives in the Baikov or parametric representations lead to identities which involve dimension shifts. These dimension shifts can be avoided by imposing a certain constraint on the total derivatives. The solutions of this constraint turn out to be a specific type of syzygies which correspond to logarithmic vector fields along the Gram determinant formed of the independent external and loop momenta. We present an explicit generating set of solutions in Baikov representation, valid for any number of loops and external momenta, obtained from the Laplace expansion of the Gram determinant. We provide a rigorous mathematical proof that this set of solutions is complete. This proof relates the logarithmic vector fields in question to ideals of submaximal minors of the Gram matrix and makes use of classical resolutions of such ideals.

    ↳ hep-thhep-phmath.AGPRD(2018)·93 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.