Thu·Jan 10, 2019Thursday·January 10, 2019

1. 01*

   Dynamical generation of low-energy couplings from quark-meson fluctuations

   Florian Divotgey🇩🇪 · Jürgen Eser🇩🇪 · Mario Mitter🇺🇸

   We extend our recent computation of the low-energy limit of the linear O(4) Quark-Meson Model. The present analysis focuses on the transformation of the resulting effective action into a nonlinearly realized effective pion action, whose higher-derivative interaction terms are parametrized by so-called low-energy couplings. Their counterparts in the linear model are determined from the Functional Renormalization Group flow of the momentum-dependent four-pion vertex, which is calculated in a fully O(4)-symmetric approximation by including also momentum-dependent {\sigma}{\pi} interactions as well as {\sigma} self-interactions. Consequently, these higher-derivative couplings are dynamically generated solely from quark and meson fluctuations, initialized at a hadronic scale. Despite our restriction to low-energy degrees of freedom, we find that the qualitative features of the fluctuation dynamics allow us to comment on the range of validity and on appropriate renormalization scales for purely pionic effective models.

   hep-phPRD(2019)·19 citations
2. 02*

   Unquenching the quark model in a non-perturbative scheme

   Pablo G. Ortega🇪🇸 · David R. Entem🇪🇸 · Francisco Fernández🇪🇸

   In recent years, the discovery in quarkonium spectrum of several states not predicted by the naive quark model has awakened a lot of interest. A possible description of such states requires the enlargement of the quark model by introducing quark-antiquark pair creation or continuum coupling effects. The unquenching of the quark models is a way to take these new components into account. In the spirit of the Cornell Model, this is usually done by coupling perturbatively a quark-antiquark state with definite quantum numbers to the meson-meson channel with closest threshold. In this work we present a method to coupled quark-antiquark states with meson-meson channels, taking into account effectively the non-perturbative coupling to all quark-antiquark states with the same quantum numbers. The method will be applied to the study of the X(3872) resonance and a comparison with the perturbative calculation will be performed.

   hep-phAdv.High Energy Phys.(2019)·5 citations
3. 03*

   All-heavy tetraquarks

   Ming-Sheng Liu🇨🇳 · Qi-Fang Lü🇨🇳 · Xian-Hui Zhong🇨🇳 · Qiang Zhao🇨🇳

   In this work we study the mass spectra of the fully-heavy tetraquark systems, i.e. $cc\bar{c}\bar{c}$, $bb\bar{b}\bar{b}$, $bb\bar{c}\bar{c}/cc\bar{b}\bar{b}$, $bc\bar{c}\bar{c}/cc\bar{b}\bar{c}$, $bc\bar{b}\bar{b}/bb\bar{b}\bar{c}$, and $bc\bar{b}\bar{c}$, within a potential model by including the linear confining potential, Coulomb potential, and spin-spin interactions. It shows that the linear confining potential has important contributions to the masses and is crucial for our understanding of the mass spectra of the fully-heavy tetraquark systems. For the fully-heavy tetraquarks $Q_1{Q}_2{\bar{Q}}_3{\bar{Q}}_4$ our explicit calculations suggest that no bound states can be formed below the thresholds of any meson pairs $(Q_1{\bar{Q}}_3)$-$(Q_2{\bar{Q}}_4)$ or $(Q_1{\bar{Q}}_4)$-$(Q_2{\bar{Q}}_3)$. Thus, we do not expect narrow fully-heavy tetraquark states to be existing in experiments.

   hep-phhep-exPRD(2019)·180 citations
4. 04*

   Asymptotic Regimes of Hadron Scattering in QCD

   V. A. Petrov🇷🇺

   Possible modes of asymptotic behavior of the amplitudes of hadron scattering in QCD are discussed. It is shown that the condition of triviality of the scattering matrix when the interaction of the fundamental fields is turned off leads to the impossibility of cross-sections that do not decrease with energy in the case of pure gluodynamics. It is also shown that in the presence of at least one type of massive quark the ban is lifted. Some consequences of the presence of an infrared fixed point are also discussed.

   hep-phhep-thTheor.Math.Phys.(2019)·2 citations
5. 05*

   Theory Requirements and Possibilities for the FCC-ee and other Future High Energy and Precision Frontier Lepton Colliders

   Alain Blondel🇨🇭 · Ayres Freitas🇺🇸 · Janusz Gluza🇵🇱 · Sven Heinemeyer🇪🇸 · Stanislaw Jadach🇵🇱 · Patrick Janot🇨🇭 · Tord Riemann🇵🇱

   The future lepton colliders proposed for the High Energy and Precision Frontier set stringent demands on theory. The most ambitious, broad-reaching and demanding project is the FCC-ee. We consider here the present status and requirements on precision calculations, possible ways forward and novel methods, to match the experimental accuracies expected at the FCC-ee. We conclude that the challenge can be tackled by a distributed collaborative effort in academic institutions around the world, provided sufficient support, which is estimated to about 500 man-years over the next 20 years.

   hep-phhep-th41 citations
6. 06*

   Theoretical uncertainties in exclusive electroproduction S-wave heavy quarkonia

   Jan Cepila🇨🇿 · Jan Nemchik🇨🇿 · Michal Krelina🇨🇱 · Roman Pasechnik🇸🇪

   In this work, we revise the conventional description of J/Psi(1S), Y(1S), Psi'(2S) and Y'(2S) elastic photo- and electroproduction off a nucleon target within the color dipole picture and carefully study various sources of theoretical uncertainties in calculations of the corresponding electroproduction cross sections. For this purpose, we test the corresponding predictions using a bulk of available dipole cross section parametrisations obtained from deep inelastic scattering data at HERA. Specifically, we provide the detailed analysis of the energy and hard-scale dependencies of quarkonia yields employing the comprehensive treatment of the quarkonia wave functions in the Schroedinger equation based approach for a set of available c-\bar{c} and b-\bar{b} interquark interaction potentials. Besides, we quantify the effect of Melosh spin rotation, the Q^2-dependence of the diffractive slope and an uncertainty due to charm and bottom quark mass variations.

   hep-phEPJC(2019)·61 citations
7. 07*

   Do T asymmetries for neutrino oscillations in uniform matter have a CP-even component?

   Jose Bernabeu🇪🇸 · Alejandro Segarra🇪🇸

   Observables of neutrino oscillations in matter have, in general, contributions from the effective matter potential. It contaminates the CP violation asymmetry adding a fake effect that has been recently disentangled from the genuine one by their different behavior under T and CPT. Is the genuine T-odd CPT-invariant component of the CP asymmetry coincident with the T asymmetry? Contrary to CP, matter effects in uniform matter cannot induce by themselves a non-vanishing T asymmetry; however, the question of the title remained open. We demonstrate that, in the presence of genuine CP violation, there is a new non-vanishing CP-even, and so CPT-odd, component in the T asymmetry in matter, which is of odd-parity in both the phase $\delta$ of the flavor mixing and the matter parameter $a$. The two disentangled components, genuine $A_{\alpha \beta }^{\mathrm{T};\mathrm{CP}}$ and fake $A_{\alpha \beta }^{\mathrm{T};\mathrm{CPT}}$, could be experimentally separated by the measurement of the two T asymmetries in matter (${\nu }_{\alpha }\leftrightarrow {\nu }_{\beta }$) and (${\bar{\nu }}_{\alpha }\leftrightarrow {\bar{\nu }}_{\beta }$). For the (${\nu }_{\mu }\leftrightarrow {\nu }_e$) transitions, the energy dependence of the new $A_{\mu e}^{\mathrm{T};\mathrm{CPT}}$ component is like the matter-induced term $A_{\mu e}^{\mathrm{CP};\mathrm{CPT}}$ of the CP asymmetry which is odd under a change of the neutrino mass hierarchy. We have thus completed the physics involved in all observable asymmetries in matter by means of their disentanglement into the three independent components, genuine $A_{\alpha \beta }^{\mathrm{CP};\mathrm{T}}$ and fake $A_{\alpha \beta }^{\mathrm{CP};\mathrm{CPT}}$ and $A_{\alpha \beta }^{\mathrm{T};\mathrm{CPT}}$.

   hep-phJHEP(2019)·11 citations
8. 08*

   Sequentially loop-generated quark and lepton mass hierarchies in an extended Inert Higgs Doublet model

   A. E. Cárcamo Hernández🇨🇱 · Sergey Kovalenko🇨🇱 · Roman Pasechnik🇸🇪 · Ivan Schmidt🇨🇱

   Extended scalar and fermion sectors offer new opportunities for generating the observed strong hierarchies in the fermion mass and mixing patterns of the Standard Model (SM). In this work, we elaborate on the prospects of a particular extension of the Inert Higgs doublet model where the SM hierarchies are generated sequentially by radiative virtual corrections in a fully renormalisable way, i.e. without adding any non-renormalisable Yukawa terms or soft-breaking operators to the scalar potential. Our model has a potential to explain the recently observed $R_K$ and $R_{K^{\ast }}$ anomalies, thanks to the non universal $U_{1X}$ assignments of the fermionic fields that yield non universal $Z^{\prime }$ couplings to fermions. We explicitly demonstrate the power of this model for generating the realistic quark, lepton and neutrino mass spectra. In particular, we show that due to the presence of both continuous and discrete family symmetries in the considered framework, the top quark acquires a tree-level mass, lighter quarks and leptons get their masses at one- and two-loop order, while neutrino masses are generated at three-loop level. The minimal field content, particle spectra and scalar potential of this model are discussed in detail.

   hep-phJHEP(2019)·18 citations
9. 09*

   Transverse densities and generalized parton distributions of $\rho$ meson in light front quark model

   Narinder Kumar🇮🇳

   We have investigated the transverse charge density for longitudinal and transversely polarized $\rho$ meson in light-front quark model (LFQM). Charge densities are obtained from the elastic form factors of the $\rho$ meson calculated in LFQM including the zero-mode contributions. We have computed the different helicity matrix elements of the $\rho$ meson. In addition to this, we have also presented the results for the generalized parton distributions (GPDs) and impact-parameter dependent parton distribution functions (ipdpdfs) of the $\rho$ meson.

   hep-phPRD(2019)·12 citations
10. 10*

    Dualities and inhomogeneous phases in dense quark matter with chiral and isospin imbalances in framework of effective model

    T. G. Khunjua🇷🇺 · K. G. Klimenko🇷🇺 · R. N. Zhokhov🇷🇺

    It has been shown in [32,33] in the framework of Nambu--Jona-Lasinio model with the assumption of spatially homogeneous condensates that in the large-$N_c$ limit ($N_c$ is the number of quark colours) there exist three dual symmetries of the thermodynamic potential, which describes dense quark matter with chiral and isospin imbalances. The main duality is between the chiral symmetry breaking and the charged pion condensation phenomena. There have been a lot of studies and hints that the ground state could be characterized by spatially inhomogeneous condensates, so the question arises if duality is a rather deep property of the phase structure or just accidental property in the homogeneous case. In this paper we have shown that even if the phase diagram contains phases with spatially inhomogeneous condensates, it still possesses the property of this main duality. Two other dual symmetries are not realized in the theory if it is investigated within an inhomogeneous approach to a ground state. From various earlier studied aspects of QCD phase diagram of isospin asymmetric matter with possible inhomogeneous condensates, in the present paper the unified picture and full phase diagram of isospin imbalanced dense quark matter have been assembled. Acting on this diagram by a dual transformation, we obtained, in the framework of an approach with spatially inhomogeneous condensates and without any calculations, a full phase diagram of chirally asymmetric dense medium. This example shows that the duality is not just entertaining mathematical property but an instrument with very high predictivity power. The obtained phase diagram is quite rich and contains various spatially inhomogeneous phases.

    hep-phhep-thJHEP(2019)·37 citations
11. 11*

    Four-loop quark form factor with quartic fundamental colour factor

    Roman N. Lee🇷🇺 · Alexander V. Smirnov🇷🇺 · Vladimir A. Smirnov🇷🇺 · Matthias Steinhauser🇩🇪

    We analytically compute the four-loop QCD corrections for the colour structure $(d_F^{abcd}{)}^2$ to the massless non-singlet quark form factor. The computation involves non-trivial non-planar integral families which have master integrals in the top sector. We compute the master integrals by introducing a second mass scale and solving differential equations with respect to the ratio of the two scales. We present details of our calculational procedure. Analytical results for the cusp and collinear anomalous dimensions, and the finite part of the form factor are presented. We also provide analytic results for all master integrals expanded up to weight eight.

    hep-phJHEP(2019)·92 citations
12. 12*

    $B_s\to K\ell \nu$ decay from lattice QCD

    A. Bazavov🇺🇸 · C. Bernard🇺🇸 · C. DeTar🇺🇸 · Daping Du🇺🇸 · A.X. El-Khadra🇺🇸 · E.D. Freeland🇺🇸 · E. Gámiz🇪🇸 · Z. Gelzer🇺🇸 · Steven Gottlieb🇺🇸 · U.M. Heller🇺🇸 · A.S. Kronfeld🇺🇸 · J. Laiho🇺🇸 and 8 other authors

    We use lattice QCD to calculate the form factors $f_{+}(q^2)$ and $f_0(q^2)$ for the semileptonic decay $B_s\to K\ell \nu$. Our calculation uses six MILC asqtad 2+1 flavor gauge-field ensembles with three lattice spacings. At the smallest and largest lattice spacing the light-quark sea mass is set to 1/10 the strange-quark mass. At the intermediate lattice spacing, we use four values for the light-quark sea mass ranging from 1/5 to 1/20 of the strange-quark mass. We use the asqtad improved staggered action for the light valence quarks, and the clover action with the Fermilab interpolation for the heavy valence bottom quark. We use SU(2) hard-kaon heavy-meson rooted staggered chiral perturbation theory to take the chiral-continuum limit. A functional $z$ expansion is used to extend the form factors to the full kinematic range. We present predictions for the differential decay rate for both $B_s\to K\mu \nu$ and $B_s\to K\tau \nu$. We also present results for the forward-backward asymmetry, the lepton polarization asymmetry, ratios of the scalar and vector form factors for the decays $B_s\to K\ell \nu$ and $B_s\to D_s\ell \nu$. Our results, together with future experimental measurements, can be used to determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$.

    ↳ hep-lathep-phPRD(2019)·83 citations
13. 13*

    The extreme orbital period in scalar hairy kerr black holes

    Yan Peng🇨🇳

    In a very interesting paper, Hod has proven that the equatorial null circular geodesic provides the extreme orbital period to circle a kerr black hole, which is closely related to the Fermat's principle. In the present paper, we extend the discussion to kerr black holes with scalar field hair. We show that the circle with the extreme orbital period is still identical to the null circular geodesic. Our analysis also implies that the Hod's theorem may be a general property in any axially symmetric spacetime with reflection symmetry on the equatorial plane.

    ↳ gr-qchep-phhep-thPLB(2019)·30 citations
14. 14*

    Quarkonium production as a function of charged-particle multiplicity in pp and p--Pb collisions measured by ALICE at the LHC

    Dhananjaya Thakur (for the ALICE Collaboration)🇮🇳

    Quarkonium production as a function of the charged-particle multiplicity could provide an insight into particle production processes at the partonic level in hadronic collisions. It is believed that multiple partonic interactions play an important role in particle production and affect both soft and hard processes. The study of correlations between quarkonia and charged-particle multiplicity may provide information about this. In this contribution, ALICE measurements of J$/\psi$ and ${\rm Y}$ production as a function of charged-particle multiplicity are presented for pp collisions at center-of-mass energies $\sqrt{s}$ = 5.02 and 13 TeV. A similar measurement performed in p\textendash Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV at both forward and backward rapidity is also discussed.

    ↳ hep-exhep-phnucl-exPoS(2019)·3 citations
15. 15*

    Weyl Consistency Conditions and ${\gamma }_5$

    C. Poole🇩🇰 · A. E. Thomsen🇩🇰

    The treatment of ${\gamma }_5$ in Dimensional Regularization leads to ambiguities in field-theoretic calculations, of which one example is the coefficient of a particular term in the four-loop gauge $\beta$-functions of the Standard Model. Using Weyl Consistency Conditions, we present a scheme-independent relation between the coefficient of this term and a corresponding term in the three-loop Yukawa $\beta$-functions, where a semi-naïve treatment of ${\gamma }_5$ is sufficient, thereby fixing this ambiguity. We briefly outline an argument by which the same method fixes similar ambiguities at higher orders.

    ↳ hep-thhep-phPRL(2019)·44 citations
16. 16*

    Six-loop $\epsilon$ expansion study of three-dimensional $n$-vector model with cubic anisotropy

    L.Ts. Adzhemyan🇷🇺 · E.V. Ivanova🇷🇺 · M.V. Kompaniets🇷🇺 · A. Kudlis🇷🇺 · A.I. Sokolov🇷🇺

    The six-loop expansions of the renormalization-group functions of ${\phi }^4$ $n$-vector model with cubic anisotropy are calculated within the minimal subtraction (MS) scheme in $4-\epsilon$ dimensions. The $\epsilon$ expansions for the cubic fixed point coordinates, critical exponents corresponding to the cubic universality class and marginal order parameter dimensionality $n_c$ separating different regimes of critical behavior are presented. Since the $\epsilon$ expansions are divergent numerical estimates of the quantities of interest are obtained employing proper resummation techniques. The numbers found are compared with their counterparts obtained earlier within various field-theoretical approaches and by lattice calculations. In particular, our analysis of $n_c$ strengthens the existing arguments in favor of stability of the cubic fixed point in the physical case $n=3$.

    ↳ cond-mat.stat-mechhep-lathep-phhep-thNPB(2019)·62 citations
17. 17*

    Kutasov-Seiberg dualities and cyclotomic polynomials

    Borut Bajc🇸🇮

    We classify all Kutasov-Seiberg type dualities in large $N_c$ SQCD with adjoints of rational $R$-charges. This is done by equating the superconformal index of the electric and magnetic theories: the obtained equation has a solution each time some product of cyclotomic polynomials has only positive coefficients. In this way we easily reproduce without any reference to the superpotential or the choice of the equations of motion (classical chiral ring) all the known dualities from the literature, while adding to them a new family with two adjoints with $R$ charges $\frac{2}{2k+1}$ and $\frac{2(k+1)}{2k+1}$ for all integers $k>1$. We argue that these new fixed points could be in their appropriate conformal windows and in some range of the Yukawas involved a low energy limit of the $D_{2k+2}$ fixed point. We try to clarify some issues connected to the difference between classical and quantum chiral ring of this new solution.

    ↳ hep-thhep-phJHEP(2019)·6 citations
18. 18*

    Spectral functions of nucleon form factors: Three-pion continua at low energies

    N. Kaiser🇩🇪 · E. Passemar🇺🇸

    We study the imaginary parts of the isoscalar electromagnetic and isovector axial form factors of the nucleon close to the $3\pi$-threshold in covariant baryon chiral perturbation theory. At the two-loop level, the contributions arising from leading and next-to-leading order chiral $\pi N$-vertices, as well as pion-induced excitations of virtual $\Delta (1232)$-isobars, are calculated. It is found that the heavy baryon treatment overestimates substantially these $3\pi$-continua. From a phenomenological analysis, that includes the narrow $\omega (783)$-resonance or the broad $a_1$-resonance, one can recognize small windows near threshold, where chiral $3\pi$-dynamics prevails. However, in the case of the isoscalar electromagnetic form factors $G_{E,M}^s(t)$, the radiative correction provided by the ${\pi }^0\gamma$-intermediate state turns out to be of similar size.

    ↳ nucl-thhep-phEPJA(2019)·15 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.