Wed·May 10, 2017Wednesday·May 10, 2017

1. 01*

   Visible neutrino decay in the light of appearance and disappearance long baseline experiments

   Alberto M. Gago🇵🇪 · Ricardo A. Gomes🇧🇷 · Abner L. G. Gomes🇧🇷 · Joel Jones-Perez🇵🇪 · Orlando L. G. Peres🇧🇷

   We investigate the present constraints from MINOS and T2K experiments for the neutrino decay scenario induced by non-diagonal couplings of Majorons to neutrinos. As novelty, on top of the typical invisible decay prescription, we add the contribution of visible decay, where final products can be observed. This new effect depends on the nature of the neutrino - Majoron coupling, which can be of scalar or pseudoscalar type. Using the combination of disappearance data from MINOS and disappearance and appearance data from T2K, for normal ordering, we constrain the decay parameter $\alpha \equiv E\Gamma$ for the heaviest neutrino, where $E$ and $\Gamma$ are the neutrino energy and width, respectively. We find that when considering visible decay within appearance data, one can improve current neutrino long-baseline constraints up to $\alpha <\mathcal{O}(10^{-5})$ eV${}^2$, at 90\% C.L., for both kinds of couplings, which is better by one order of magnitude compared to previous bounds.

   hep-phJHEP(2017)·50 citations
2. 02*

   Quarkonium $h$ States As Arbiters of Exoticity

   Richard F. Lebed🇺🇸 · Eric S. Swanson🇺🇸

   The mass splitting between the quarkonium spin-singlet state $h$ ($J^{PC}=1^{+-}$) and the spin average of the quarkonium spin-triplet states $\chi$ ($J^{PC}=0^{++},1^{++},2^{++}$) is seen to be astonishingly small, not only in the charmonium and bottomonium cases where the relevant masses have been measured, but in positronium as well. We find, both in nonrelativistic quark models and in NRQCD, that this hyperfine splitting is so small that it can be used as a test of the pure $Q\bar{Q}$ content of the states. We discuss the $2P$ states of charmonium in the vicinity of $3.9$ GeV, where the putative exotics $X(3872)$ and $X(3915)$ have been seen and a new ${\chi }_{c0}(2P)$ candidate has been observed at Belle.

   hep-phhep-exPRD(2017)·22 citations
3. 03*

   A systematic study of mass spectra and strong decay of strange mesons

   Cheng-Qun Pang🇨🇳 · Jun-Zhang Wang🇨🇳 · Xiang Liu🇨🇳 · Takayuki Matsuki🇯🇵

   The mass spectrum of the kaon family is analyzed by the {modified} Godfrey-Isgur model with a color screening effect approximating the kaon as a heavy-light meson system. This analysis gives us the structure and possible assignments of the observed kaon candidates, which can be tested by comparing the theoretical results of their two-body strong decays with the experimental data. Additionally, prediction of some partial decay widths is made on the kaons still missing in experiment. This study is crucial to establishing the kaon family and searching for their higher excitations in the future.

   hep-phEPJC(2017)·69 citations
4. 04*

   Wigner distributions for an electron

   Narinder Kumar🇮🇳 · Chandan Mondal🇨🇳

   We study the Wigner distributions for a physical electron, which reveal the multidimensional images of the electron. The physical electron is considered as a composite system of a bare electron and photon. The Wigner distributions for unpolarized, longitudinally polarized and transversely polarized electron are presented in transverse momentum plane as well as in impact parameter plane. The spin-spin correlations between the bare electron and the physical electron are discussed. We also evaluate all the leading twist generalized transverse momentum distributions (GTMDs) for electron.

   hep-phNPB(2018)·22 citations
5. 05*

   Bayesian analysis of quark spectral properties from the Dyson-Schwinger equation

   Christian S. Fischer🇩🇪 · Jan M. Pawlowski🇩🇪 · Alexander Rothkopf🇩🇪 · Christian A. Welzbacher🇩🇪

   We report results on the quark spectral function in the Landau gauge at finite temperature determined from its Dyson-Schwinger equation. Compared to earlier quenched results this study encompasses unquenched $N_f=2+1$ fermion flavors in the medium. For the reconstruction of real-time spectra we deploy a recent Bayesian approach (BR method) and develop a new prior in order to better assess the inherent systematic uncertainties. We identify the quark quasi-particle spectrum and analyze the (non-)appearance of zero modes at or around the pseudo-critical temperature. In both, the fully unquenched system and a simpler truncation using a model for the gluon propagator we observe a characteristic three-peak structure at zero three-momentum. The temperature dependence of these structures in case of the gluon propagator model is different than observed in previous studies. For the back-coupled and unquenched case we find interesting modifications at and around the pseudo-critical transition temperature.

   hep-phnucl-thPRD(2018)·40 citations
6. 06*

   Analysis of the strong vertexes of ${\Sigma }_c^{\ast }ND$ and ${\Sigma }_b^{\ast }NB$ in QCD sum rules

   Guo Liang Yu🇨🇳 · Zhi Gang Wang🇨🇳 · Zhen Yu Li🇨🇳

   In this article, we analyze the strong vertexes ${\Sigma }_c^{\ast }ND$ and ${\Sigma }_b^{\ast }NB$ using the three-point QCD sum rules under the Dirac structure of $q/p/{\gamma }_{\mu }$. We perform our analysis by considering the contributions of the perturbative part and the condensate terms of $<\overline{q}q>$ and $<\frac{{\alpha }_s}{\pi }GG>$. After the form factors are calculated, they are then fitted into analytical functions which are used to get the strong coupling constants for these two vertexes. The final results are $g_{{\Sigma }_c^{\ast }ND}=7.19_{-3.11}^{+8.49}\pm 1.76$ and $g_{{\Sigma }_b^{\ast }NB}=10.54_{-5.23}^{+15.59}\pm 1.82$.

   hep-phInt.J.Mod.Phys.A(2017)·4 citations
7. 07*

   Feasibility of measuring the magnetic dipole moments of the charm baryons at the LHC using bent crystals

   A.S. Fomin🇫🇷 · A.Yu. Korchin🇺🇦 · A. Stocchi🇫🇷 · O.A. Bezshyyko🇺🇦 · L. Burmistrov🇫🇷 · S.P. Fomin🇺🇦 · I.V. Kirillin🇺🇦 · L. Massacrier🇫🇷 · A. Natochii🇫🇷 · P. Robbe🇫🇷 · W. Scandale🇨🇭 · N.F. Shul'ga🇺🇦

   In this paper we revisit the idea of measuring the magnetic dipole moments of the charm baryons and, in particular, of charmed Lambda by studying the spin precession induced by the strong effective magnetic field inside the channels of a bent crystal. We present a detailed sensitivity study showing the feasibility of such an experiment at the LHC in the coming years.

   hep-phJHEP(2017)·61 citations
8. 08*

   Anomaly-Free Models for Flavour Anomalies

   John Ellis🇬🇧 · Malcolm Fairbairn🇬🇧 · Patrick Tunney🇬🇧

   We explore the constraints imposed by the cancellation of triangle anomalies on models in which the flavour anomalies reported by LHCb and other experiments are due to an extra U(1)' gauge boson Z'. We assume universal and rational U(1)' charges for the first two generations of left-handed quarks and of right-handed up-type quarks but allow different charges for their third-generation counterparts. If the right-handed charges vanish, cancellation of the triangle anomalies requires all the quark U(1)' charges to vanish, if there are either no exotic fermions or there is only one Standard Model singlet dark matter (DM) fermion. There are non-trivial anomaly-free models with more than one such `dark' fermion, or with a single DM fermion if right-handed up-type quarks have non-zero U(1)' charges. In some of the latter models the U(1)' couplings of the first- and second-generation quarks all vanish, weakening the LHC Z' constraint, and in some other models the DM particle has purely axial couplings, weakening the direct DM scattering constraint. We also consider models in which anomalies are cancelled via extra vector-like leptons, showing how the prospective LHC Z' constraint may be weakened because the $Z^{\prime }\to {\mu }^{+}{\mu }^{-}$ branching ratio is suppressed relative to other decay modes.

   hep-phhep-exEPJC(2018)·93 citations
9. 09*

   Determination of the strong coupling at NNLO from jet production in DIS

   Daniel Britzger (on behalf of the collaboration)🇩🇪

   A first determination of the strong coupling ${\alpha }_s(m_Z)$ in next-to-next-to-leading order (NNLO) from inclusive jet and dijet production cross sections in deep-inelastic scattering at HERA is presented. Data collected by the H1 experiment in the years 1995 to 2007 covering the range of momentum transfer $5.5<Q^2<15000{\mathrm{GeV}}^2$ and jet transverse momenta $P_T>4.5\mathrm{GeV}$ are explored. The strong coupling is determined in a fit to inclusive jet and dijet data to ${\alpha }_s(m_Z)=0.1157(6{)}_{\exp }{(}_{-26}^{+31}{)}_{\mathrm{theo}}$. Further studies on the phenomenological application of the new NNLO calculations and on fits to the individual data sets are presented. The running of the strong coupling is probed in a single experiment over one order of magnitude in the remormalisation scale and consistency with the QCD expectations is found.

   hep-phhep-exPoS(2018)·1 citation
10. 10*

    On Light Resonance Interpretations of the B Decay Anomalies

    Fady Bishara🇬🇧 · Ulrich Haisch🇬🇧 · Pier Francesco Monni🇨🇭

    We sketch a novel method to search for light di-leptonic resonances by exploiting precision measurements of Drell-Yan production. Motivated by the recent hints of lepton flavour universality violation in $B\to K^{\ast }{\ell }^{+}{\ell }^{-}$, we illustrate our proposal by studying the case of spin-1 resonances that couple to muons and have masses in the range of a few GeV. We show that the existing LHC data on $pp\to Z/{\gamma }^{\ast }\to {\mu }^{+}{\mu }^{-}$ put non-trivial constraints on light di-muon resonance interpretations of $B$ decay anomalies in a model-independent fashion. The impact of our proposal on the long-standing discrepancy in the anomalous magnetic moment of the muon is also briefly discussed.

    hep-phhep-exPRD(2017)·36 citations
11. 11*

    Electroweak and Higgs Boson Internal Bremsstrahlung: General considerations for Majorana dark matter annihilation and application to MSSM neutralinos

    Torsten Bringmann🇳🇴 · Francesca Calore🇫🇷 · Ahmad Galea🇳🇴 · Mathias Garny🇩🇪

    It is well known that the annihilation of Majorana dark matter into fermions is helicity suppressed. Here, we point out that the underlying mechanism is a subtle combination of two distinct effects, and we present a comprehensive analysis of how the suppression can be partially or fully lifted by the internal bremsstrahlung of an additional boson in the final state. As a concrete illustration, we compute analytically the full amplitudes and annihilation rates of supersymmetric neutralinos to final states that contain any combination of two standard model fermions, plus one electroweak gauge boson or one of the five physical Higgs bosons that appear in the minimal supersymmetric standard model. We classify the various ways in which these three-body rates can be large compared to the two-body rates, identifying cases that have not been pointed out before. In our analysis, we put special emphasis on how to avoid the double counting of identical kinematic situations that appear for two-body and three-body final states, in particular on how to correctly treat differential rates and the spectrum of the resulting stable particles that is relevant for indirect dark matter searches. We find that both the total annihilation rates and the yields can be significantly enhanced when taking into account the corrections computed here, in particular for models with somewhat small annihilation rates at tree-level which otherwise would not be testable with indirect dark matter searches. Even more importantly, however, we find that the resulting annihilation spectra of positrons, neutrinos, gamma-rays and antiprotons differ in general substantially from the model-independent spectra that are commonly adopted, for these final states, when constraining particle dark matter with indirect detection experiments.

    hep-phJHEP(2017)·34 citations
12. 12*

    Hunting down massless dark photons in kaon physics

    M. Fabbrichesi🇮🇹 · E. Gabrielli🇮🇹 · B. Mele🇮🇹

    If dark photons are massless, they couple to standard-model particles only via higher dimensional operators, while the kinetic mixing with photons, which motivates most of the current experimental searches, is absent. We consider the effect of possible flavor-changing magnetic-dipole couplings of massless dark photons in kaon physics. In particular, we study the branching ratio for the process $K^{+}\to {\pi }^{+}{\pi }^0\bar{\gamma }$ with a simplified-model approach, assuming the chiral quark model to evaluate the hadronic matrix element. Possible effects in the $K^0$-${\bar{K}}^0$ mixing are taken into account. We find that branching ratios up to $O(10^{-7})$ are allowed---depending on the dark-sector masses and couplings. Such large branching ratios for $K^{+}\to {\pi }^{+}{\pi }^0\bar{\gamma }$ could be of interest for experiments dedicated to rare $K^{+}$ decays like NA62 at CERN, where $\bar{\gamma }$ can be detected as a massless invisible system.

    hep-phhep-exPRL(2017)·38 citations
13. 13*

    Calculations of Shear, Bulk viscosities and Electrical conductivity in Polyakov-Quark-Meson model

    Pracheta Singha🇮🇳 · Aman Abhishek🇮🇳 · Guru Kadam🇮🇳 · Sabyasachi Ghosh🇮🇳 · Hiranmaya Mishra🇮🇳

    We have evaluated the transport coefficients of quark and hadronic matter in the frame work of Polyakov-Quark-Meson model. The thermal widths of quarks and mesons, which inversely control the strength of these transport coefficients, are obtained from the imaginary part of their respective self-energies at finite temperature. Due to the threshold conditions of their self energies, some limited temperature regions of quark and hadronic phase become relevant for our numerical predictions on transport coefficients, which are grossly in agreement with earlier results.

    ↳ nucl-thhep-phJ.Phys.G(2019)·43 citations
14. 14*

    Monopole-antimonopole Interaction Potential

    Ayush Saurabh🇺🇸 · Tanmay Vachaspati🇺🇸

    We numerically study the interactions of twisted monopole-antimonopole pairs in the 't Hooft-Polyakov model for a range of values of the scalar to vector mass ratio. We also recover the sphaleron solution at maximum twist discovered by Taubes, and map out its energy and size as functions of parameters.

    ↳ hep-thhep-phPRD(2017)·20 citations
15. 15*

    Imprints of fluctuating proton shapes on flow in proton-lead collisions at the LHC

    Heikki Mäntysaari🇺🇸 · Björn Schenke🇺🇸 · Chun Shen🇺🇸 · Prithwish Tribedy🇺🇸

    Results for particle production in root-s = 5.02 TeV p+Pb collisions at the Large Hadron Collider within a combined classical Yang-Mills and relativistic viscous hydrodynamic calculation are presented. We emphasize the importance of sub-nucleon scale fluctuations in the proton projectile to describe the experimentally observed azimuthal harmonic coefficients, demonstrating their sensitivity to the proton shape. We stress that the proton shape and its fluctuations are not free parameters in our calculations. Instead, they have been constrained using experimental data from HERA on exclusive vector meson production. Including temperature dependent shear and bulk viscosities, as well as UrQMD for the low temperature regime, we present results for mean transverse momenta, harmonic flow coefficients for charged hadrons and identified particles, as well as Hanbury-Brown-Twiss radii.

    ↳ nucl-thhep-phPLB(2017)·175 citations
16. 16*

    Phase structure of NJL model with weak renormalization group

    Ken-Ichi Aoki🇯🇵 · Shin-Ichiro Kumamoto🇯🇵 · Masatoshi Yamada🇩🇪

    We analyze the chiral phase structure of the Nambu--Jona-Lasinio model at finite temperature and density by using the functional renormalization group (FRG). The renormalization group (RG) equation for the fermionic effective potential $V(\sigma ;t)$ is given as a partial differential equation, where $\sigma :=\bar{\psi }\psi$ and $t$ is a dimensionless RG scale. When the dynamical chiral symmetry breaking (D$\chi$SB) occurs at a certain scale $t_c$, $V(\sigma ;t)$ has singularities originated from the phase transitions, and then one cannot follow RG flows after $t_c$. In this study, we introduce the weak solution method to the RG equation in order to follow the RG flows after the D$\chi$SB and to evaluate the dynamical mass and the chiral condensate in low energy scales. It is shown that the weak solution of the RG equation correctly captures vacuum structures and critical phenomena within the pure fermionic system. We show the chiral phase diagram on temperature, chemical potential and the four-Fermi coupling constant.

    ↳ hep-thcond-mat.stat-mechhep-phnucl-thNPB(2018)·33 citations
17. 17*

    Dynamical dissociation of quarkonia by wave function decoherence

    Shiori Kajimoto🇯🇵 · Yukinao Akamatsu🇯🇵 · Masayuki Asakawa🇯🇵 · Alexander Rothkopf🇩🇪

    We investigate the real-time evolution of quarkonium bound states in a quark-gluon plasma in one dimension using an improved QCD based stochastic potential model. This model describes the quarkonium dynamics in terms of a Schrödinger equation with an in-medium potential and two noise terms encoding the residual interactions between the heavy quarks and the medium. The probabilities of bound states in a static medium and in a boost-invariantly expanding quark-gluon plasma are discussed. We draw two conclusions from our results: One is that the outcome of the stochastic potential model is qualitatively consistent with the experimental data in relativistic heavy-ion collisions. The other is that the noise plays an important role in order to describe quarkonium dynamics in medium, in particular it causes decoherence of the quarkonium wave function. The effectiveness of decoherence is controlled by a new length scale $l_{\mathrm{corr}}$. It represents the noise correlation length and its effect has not been included in existing phenomenological studies.

    ↳ nucl-thhep-phnucl-exPRD(2018)·90 citations
18. 18*

    A higher-order Skyrme model

    Sven Bjarke Gudnason🇨🇳 · Muneto Nitta🇯🇵

    We propose a higher-order Skyrme model with derivative terms of eighth, tenth and twelfth order. Our construction yields simple and easy-to-interpret higher-order Lagrangians. We first show that a Skyrmion with higher-order terms proposed by Marleau has an instability in the form of a baby-Skyrmion string, while the static energies of our construction are positive definite, implying stability against time-independent perturbations. However, we also find that the Hamiltonians of our construction possess two kinds of dynamical instabilities, which may indicate the instability with respect to time-dependent perturbations. Different from the well-known Ostrogradsky instability, the instabilities that we find are intrinsically of nonlinear nature and also due to the fact that even powers of the inverse metric gives a ghost-like higher-order kinetic-like term. The vacuum state is, however, stable. Finally, we show that at sufficiently low energies, our Hamiltonians in the simplest cases, are stable against time-dependent perturbations.

    ↳ hep-thhep-phJHEP(2017)·26 citations
19. 19*

    Four-Loop Nonplanar Cusp Anomalous Dimension in N=4 Supersymmetric Yang-Mills Theory

    Rutger H. Boels🇩🇪 · Tobias Huber🇩🇪 · Gang Yang🇨🇳

    The light-like cusp anomalous dimension is a universal function that controls infrared divergences in quite general quantum field theories. In the maximally supersymmetric Yang-Mills theory this function is fixed fully by integrability to the three-loop order. At four loops a non-planar correction appears which we obtain for the first time from a numerical computation of the Sudakov form factor. Key ingredients are widely applicable methods to control the number-theoretic aspects of the appearing integrals. Our result shows explicitly that quadratic Casimir scaling breaks down at four loops.

    ↳ hep-thhep-phPRL(2017)·84 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.