Fri·Jan 11, 2019Friday·January 11, 2019

1. 01*

   Anapole Dark Matter Interactions as Soft Hidden Photons

   Paola Arias🇨🇱 · Jorge Gamboa🇨🇱 · Natalia Tapia🇨🇱

   We propose a model where the anapole appears as a hidden photon that is coupled to visible matter through a kinetic mixing. For low momentum $|\mathbf{p}|\ll M$ where $M$ is the cutoff the model (soft hidden photons limit) is reduced to the Ho-Scherrer description. We show that the hidden gauge boson is stable and therefore the hidden photons, indeed, are candidates for dark matter. Our approach shows that anapole and kinetic mixing terms are equivalent descriptions seen from different scales of energy.

   hep-phhep-thPLB(2019)·4 citations
2. 02*

   Discovery reach for wino and higgsino dark matter with a disappearing track signature at a 100 TeV $pp$ collider

   Masahiko Saito🇯🇵 · Ryu Sawada🇯🇵 · Koji Terashi🇯🇵 · Shoji Asai🇯🇵

   Within the theory of supersymmetry, the lightest neutralino is a dark matter candidate and is often assumed to be the lightest supersymmetric particle (LSP) as well. If the neutral wino or higgsino is dark matter, the upper limit of the LSP mass is determined by the observed relic density of dark matter. If the LSP is a nearly-pure neutral state of the wino or higgsino, the lightest chargino state is expected to have a significant lifetime due to a tiny mass difference between the LSP and the chargino. This article presents discovery potential of the 100 TeV future circular hadron collider (FCC) for the wino and higgsino dark matter using a disappearing-track signature. The search strategy to extend the discovery reach to the thermal limits of wino/higgsino dark matter is discussed with detailed studies on the background rate and the reference design of the FCC-hadron detector under possible running scenarios of the FCC-hadron machine. A proposal of modifying the detector layout and several ideas to improve the sensitivity further are also discussed.

   hep-phhep-exEPJC(2019)·56 citations
3. 03*

   On Experimental Confirmation of the Corrections to the Fermi's golden rule

   Kenzo Ishikawa🇯🇵 · Osamu Jinnouchi🇯🇵 · Arisa Kubota🇯🇵 · Terry Sloan🇬🇧 · Takuya H. Tatsuishi🇯🇵 · Risa Ushioda🇯🇵

   Standards calculations by the Fermi's Golden rule involve approximations. These approximations could lead to deviations from the predictions of the standard model as discussed in another paper. In this paper we propose experimental searches for such deviations in the two photon spectra from the decay of the neutral pion in the process $\varphi \to {\pi }^{+}{\pi }^{-}{\pi }^0$ and in the annihilation of the positron from nclear $\beta$ decay.

   hep-phPTEP(2019)·6 citations
4. 04*

   Nonvanishing pion masses for vanishing bare quark masses

   Aiichi Iwazaki🇯🇵

   It is generally thought that pion masses vanish when bare light quark masses $m_q$ vanish. The pions are Nambu-Goldstone bosons of chiral $S{U}_A(2)$ symmetry. We discuss a possibility that even when $m_q=0$, the chiral symmetry is explicitly broken in strong coupled QCD, while it is not in weakly coupled QCD. The point is that QCD monopoles are dynamical degrees of freedom in the strong coupled QCD. We show that the monopole quark interactions break the chiral $U_5(1)$ symmetry as well as the chiral $S{U}_A(2)$ symmetry. They are weak relative to the other chiral symmetric interactions of quarks and gluons. These weak interactions produce small pion masses as well as quark masses $\sim 20$MeV in the phase with the monopole condensation. The presence of the interactions modifies the Gell-Mann Oakes Renner relation. Using the relation we predict the value $(-⟨\bar{q}q⟩{)}^{1/3}\simeq 160$MeV. We also show that the monopole quark interactions do not prevent the monopole condensation in dual superconducting model.

   hep-ph2 citations
5. 05*

   Dense quark matter with chiral and isospin imbalance: NJL-model consideration

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

   Isospin asymmetry is the well-known property of dense quark matter, which exists in the compact stars and is produced in heavy ion collisions. On the other hand, the chiral imbalance between left- and right-handed quarks is another highly anticipated phenomenon that could occur in the dense quark matter. To investigate quark matter under these conditions, we take into account baryon -- ${\mu }_B$, isospin -- ${\mu }_I$ and chiral isospin -- ${\mu }_{I5}$ chemical potentials and study QCD phase portrait using NJL${}_4$ model generalized to two massive quarks that could condense into the pion condensation. We have shown that the chiral isospin chemical potential ${\mu }_{I5}$ generates pion condensation in isospin asymmetric quark matter. Also, we have investigated discrete symmetry (duality) between chiral and pion condensates in the case of massless quarks, which stay relatively instructive even if the quarks have bare mass. To describe hot dense quark matter, in addition to the above-mentioned chemical potentials, we introduce non-zero temperatures into consideration.

   hep-phhep-thEPJ Web Conf.(2018)·12 citations
6. 06*

   The pseudoscalar meson and baryon octet interaction with strangeness zero in the unitary coupled-channel approximation

   Bao-Xi Sun🇨🇳 · Si-Yu Zhao🇨🇳 · Xiang-Yu Wang🇨🇳

   The interaction of the pseudoscalar meson and the baryon octet is investigated by solving the Bethe-Salpeter equation in the unitary coupled-channel approximation, In addition to the Weinberg-Tomozawa term, the contribution of the $s-$ and $u-$ channel potentials in the S-wave approximation are taken into account. In the sector of isospin $I=1/2$ and strangeness $S=0$, a pole is detected in the reasonable region on the complex energy plane of $\sqrt{s}$ in the center of mass frame by analyzing the behavior of the scattering amplitude, which is higher than the $\eta N$ threshold and lies on the third Riemann sheet. Thus it can be regarded as a resonance state and might correspond to the $N(1535)$ particle in the review of the Particle Data Group(PDG). The coupling constants of this resonance state to the $\pi N$, $\eta N$, $K\Lambda$ and $K\Sigma$ channels are calculated, and it is found that this resonance state couples strongly to the hidden strange channels. Apparently, the hidden strange channels play an important role in the generation of the resonance state with strangeness zero. The interaction of the pseudoscalar meson and the baryon octet is repulsive in the sector of isospin $I=3/2$ and strangeness $S=0$, therefore, no resonance state can be generated dynamically.

   hep-phnucl-thCPC(2019)·5 citations
7. 07*

   New Probes for Axion-like Particles at Hadron Colliders

   Javad Ebadi🇮🇷 · Sara Khatibi🇮🇷 · Mojtaba Mohammadi Najafabadi🇮🇷

   Axion-like particles (ALPs) appear from spontaneous global symmetry breaking in many extensions of the Standard Model (SM). In this paper, we find bounds on ALP ($a$) model parameters at the LHC from the ALP production associated with a photon and a jet ($j+\gamma +a$) as well as single top and top quark pairs ($t+j+a$, $t\bar{t}+a$) in a model independent approach. In particular, it is shown that the ALP production associated with a photon plus a jet at the LHC is a promising channel with significant sensitivity to probe the ALP couplings to gluons and electroweak gauge bosons. The prospects are presented at the High Luminosity LHC including a realistic detector simulation and pile up effects. Furthermore, the ALP model is examined through its contributions to the top quark (chromo)magnetic dipole moments. It is shown that the top quark magnetic and chromomagnetic dipole moments enable us to probe the ALP couplings to top quark and gauge bosons at a time. The constraints are complementary to those obtained from direct searches, as they are sensitive to light ALPs.

   hep-phPRD(2019)·60 citations
8. 08*

   Flavor symmetry breaking of the nucleon sea in the statistical approach

   Claude Bourrely🇫🇷 · Jacques Soffer🇺🇸

   The flavor structure of the nucleon sea provides unique information to test the statistical parton distributions approach, which imposes strong relations between quark and antiquarks. These properties for unpolarized and helicity distributions have been verified up to now by recent data. We will present here some new results which are a real challenge, also for forthcoming accurate experimental results, mainly in the high Bjorken-$x$ region.

   hep-ph4 citations
9. 09*

   Muon-electron scattering at NNLO: the hadronic corrections

   Matteo Fael🇩🇪 · Massimo Passera🇮🇹

   The Standard Model prediction for muon-electron scattering beyond leading order requires the inclusion of QCD contributions which cannot be computed perturbatively. At next-to- and next-to-next-to-leading order, they arise from one- and two-loop diagrams with hadronic vacuum polarization insertions in the photon propagator. We present their evaluation using the dispersive approach with hadronic $e^{+}{e}^{-}$ annihilation data and estimate their uncertainty. We find that these corrections are crucial for the analysis of future high-precision muon-electron scattering data, like those of the recently proposed MUonE experiment at CERN.

   hep-phhep-exPRL(2019)·58 citations
10. 10*

    Radiative decay of the $X(3872)$ as a mixed molecule-charmonium state in effective field theory

    E. Cincioglu🇹🇷 · A. Ozpineci🇹🇷

    Assuming that $X(3872)$ is a mixture between $2P$ charmonium and $\bar{D}{D}^{\ast }$ molecular states with $J^{PC}=1^{++}$, an analysis of $X(3872)$ radiative decays into $J/\psi \gamma$ and $\psi (2S)\gamma$ is presented. The modification of the radiative branching ratio due to possible constructive or destructive interferences between the meson-loop and the short-distance contact term, which is modeled by a charm quark loop, is shown. The model predictions are shown to be compatible with the experimentally determined ratio of the mentioned branching fractions for a wide range of the $X(3872)$ charmonium content. In the case of the destructive interference, a strong restriction on the charmonium admixture is found.

    hep-phPLB(2019)·10 citations
11. 11*

    TopFitter: Fitting top-quark Wilson Coefficients to Run II data

    Stephen Brown🇬🇧 · Andy Buckley🇬🇧 · Christoph Englert🇬🇧 · James Ferrando🇩🇪 · Peter Galler🇬🇧 · David J Miller🇬🇧 · Liam Moore🇧🇪 · Michael Russell🇩🇪 · Chris White🇬🇧 · Neil Warrack🇬🇧

    We describe the latest TopFitter analysis, which uses top quark observables to fit the Wilson Coefficients of the SM augmented with dimension-6 operators. In particular, we discuss the inclusion of new LHC Run II data and the implementation of particle-level observables.

    hep-phPoS(2019)·24 citations
12. 12*

    Minimal Radiative Neutrino Masses

    Christiane Klein🇩🇪 · Manfred Lindner🇩🇪 · Sebastian Ohmer🇩🇪

    We conduct a systematic search for neutrino mass models which only radiatively produce the dimension-5 Weinberg operator. We thereby do not allow for additional symmetries beyond the Standard Model gauge symmetry and we restrict ourselves to minimal models. We also include stable fractionally charged and coloured particles in our search. Additionally, we proof that there is a unique model with three new fermionic representations where no new scalars are required to generate neutrino masses at loop level. This model further has a potential dark matter candidate and introduces a general mechanism for loop-suppression of the neutrino mass via a fermionic ladder

    hep-phJHEP(2019)·35 citations
13. 13*

    A new perspective for the magnetic corrections to $\pi$-$\pi$ Scattering Lengths in the Linear Sigma Model

    M. Loewe🇨🇱 · L. Monje🇨🇱 · E. Muñoz🇨🇱 · A. Raya🇲🇽 · R. Zamora🇨🇱

    In this article, a new perspective for obtaining the magnetic evolution of $\pi -\pi$ scattering lengths in the frame of the linear sigma model is presented. When computing the relevant one-loop diagrams that contribute to these parameters, the sum over Landau levels --emerging from the expansion of the Schwinger propagator-- is handled in a novel way that could also be applied to the calculation of other magnetic-type corrections. Essentially, we have obtained an expansion in terms of Hurwitz Zeta functions. It is necessary to regularize our expressions by an appropriate physical subtraction when $|qB|\to 0$ ($q$ the meson charge and $B$ the magnetic field strength). In this way, we are able to interpolate between the very high magnetic field strength region, usually handled in terms of the Lowest Landau Level (LLA) approximation, and the weak field region, discussed in a previous paper by some of us, which is based on an appropriate expansion of the Schwinger propagator up to order $|qB{|}^2$. Our results for the scattering lengths parameters produce a soft evolution in a wide region of magnetic field strengths, reducing to the previously found expressions in both limits.

    hep-phhep-thPRD(2019)·10 citations
14. 14*

    Dark Photon Dark Matter from a Network of Cosmic Strings

    Andrew J. Long🇺🇸 · Lian-Tao Wang🇺🇸

    We study the production of ultra-light dark photons from a network of near-global, Abelian-Higgs cosmic strings. We find that dark photons produced in this way are nonrelativistic today and can make up all of the dark matter for dark photon masses as small as $m_A\sim 10^{-22}\mathrm{eV}$.

    hep-phPRD(2019)·175 citations
15. 15*

    Joint Two-Dimensional Resummation in $q_T$ and $0$-Jettiness at NNLL

    Gillian Lustermans🇳🇱 · Johannes K. L. Michel🇩🇪 · Frank J. Tackmann🇩🇪 · Wouter J. Waalewijn🇳🇱

    We consider Drell-Yan production $pp\to Z/{\gamma }^{\ast }\to {\ell }^{+}{\ell }^{-}$ with the simultaneous measurement of the $Z$-boson transverse momentum $q_T$ and $0$-jettiness ${\mathcal{T}}_0$. Since both observables resolve the initial-state QCD radiation, the double-differential cross section in $q_T$ and ${\mathcal{T}}_0$ contains Sudakov double logarithms of both $q_T/Q$ and ${\mathcal{T}}_0/Q$, where $Q\sim m_Z$ is the dilepton invariant mass. We simultaneously resum the logarithms in $q_T$ and ${\mathcal{T}}_0$ to next-to-next-to-leading logarithmic order (NNLL) matched to next-to-leading fixed order (NLO). Our results provide the first genuinely two-dimensional analytic Sudakov resummation for initial-state radiation. Integrating the resummed double-differential spectrum with an appropriate scale choice over either ${\mathcal{T}}_0$ or $q_T$ recovers the corresponding single-differential resummation for the remaining variable. We discuss in detail the required effective field theory setups and their combination using two-dimensional resummation profile scales. We also introduce a new method to perform the $q_T$ resummation where the underlying resummation is carried out in impact-parameter space, but is consistently turned off depending on the momentum-space target value for $q_T$. Our methods apply at any order and for any color-singlet production process, such that our results can be systematically extended when the relevant perturbative ingredients become available.

    hep-phJHEP(2019)·63 citations
16. 16*

    Phase Transitions and Gravitational Wave Tests of Pseudo-Goldstone Dark Matter in the Softly Broken U(1) Scalar Singlet Model

    Kristjan Kannike🇪🇪 · Martti Raidal🇪🇪

    We study phase transitions in a softly broken $U(1)$ complex singlet scalar model in which the dark matter is the pseudo-scalar part of a singlet whose direct detection coupling to matter is strongly suppressed. Our aim is to find ways to test this model with the stochastic gravitational wave background from the scalar phase transition. We find that the phase transition which induces vacuum expectation values for both the Higgs boson and the singlet - necessary to provide a realistic dark matter candidate - is always of the second order. If the stochastic gravitational wave background characteristic to a first order phase transition will be discovered by interferometers, the soft breaking of $U(1)$ cannot be the explanation to the suppressed dark matter-baryon coupling, providing a conclusive negative test for this class of singlet models.

    hep-phPRD(2019)·48 citations
17. 17*

    The pion-nucleon $\sigma$ term from pionic atoms

    E. Friedman🇮🇱 · A. Gal🇮🇱

    Earlier work suggested that the in-medium $\pi N$ threshold isovector amplitude $b_1(\rho )$ gets renormalized in pionic atoms by about 30% away from its $\rho =0$ free-space value, relating such renormalization to the leading low-density decrease of the in-medium quark condensate $<\bar{q}q>$ and the pion decay constant $f_{\pi }$ in terms of the pion-nucleon $\sigma$ term ${\sigma }_{\pi N}$. Accepting the validity of this approach, we extracted ${\sigma }_{\pi N}$ from a large-scale fit of pionic-atom level shift and width data across the periodic table. Our fitted value ${\sigma }_{\pi N}=57\pm 7$ MeV is robust with respect to variation of $\pi N$ interaction terms other than the isovector $s$-wave term with which ${\sigma }_{\pi N}$ was associated. Higher order corrections to the leading order in density involve some cancellations, suggesting thereby only a few percent overall systematic uncertainty. The value of ${\sigma }_{\pi N}$ derived here agrees with values obtained in several recent studies based on near-threshold $\pi N$ phenomenology, but sharply disagrees with values obtained in recent direct lattice QCD calculations.

    ↳ nucl-thhep-phnucl-exPLB(2019)·47 citations
18. 18*

    The CEPC input for the European Strategy for Particle Physics - Physics and Detector

    CEPC Physics-Detector Study Group

    The Circular Electron Positron Collider (CEPC) is a large-scale future collider facility that can serve as a factory of the Higgs boson, the W boson and the Z boson. This document provides a brief summary of the CEPC physics potential and the detector design concepts, both of which are laid out in detail in the Conceptual Design Report (CDR) released in November 2018. We also outline future directions and challenges. In the Addendum, we briefly describe the planning and the international organization of the CEPC. The next step for the CEPC team is to perform detailed technical design studies. Effective international collaboration would be crucial at this stage. This submission for consideration by the ESPP is part of our dedicated effort in seeking international collaboration and support. Given the importance of the precision Higgs boson measurements, the ongoing CEPC activities do not diminish our interests in participating in the international collaborations of other future electron-positron collider based Higgs factories.

    ↳ hep-exhep-ph13 citations
19. 19*

    Unification of Flavor, CP, and Modular Symmetries

    Alexander Baur🇩🇪 · Hans Peter Nilles🇩🇪 · Andreas Trautner🇩🇪 · Patrick K.S. Vaudrevange🇩🇪

    Flavor symmetry plays a crucial role in the standard model of particle physics but its origin is still unknown. We develop a new method (based on outer automorphisms of the Narain space group) to determine flavor symmetries within compactified string theory. A picture emerges where traditional (discrete) flavor symmetries, CP-like symmetries and modular symmetries (like T-duality) of string theory combine to unified flavor symmetries. The groups depend on the geometry of compact space and the geographical location of fields in the extra dimensions. We observe a phenomenon of "local flavor groups" with potentially different flavor symmetries for the various sectors of quarks and leptons. This should allow interesting connections to existing bottom-up attempts in flavor model building.

    ↳ hep-thhep-phPLB(2019)·207 citations
20. 20*

    Phase Transitions in Neutron Stars

    V. Dexheimer🇺🇸 · L. T. T. Soethe🇧🇷 · J. Roark🇺🇸 · R. O. Gomes🇩🇪 · S. O. Kepler🇧🇷 · S. Schramm🇩🇪

    In this paper we review the most common descriptions for the first order phase transition to deconfined quark matter in the core of neutron stars. We also present a new description of these phase transitions in the core of proto-neutron stars, in which more constraints are enforced so as to include trapped neutrinos. Finally, we calculate the emission of gravitational waves associated with deconfinement phase transitions, discuss the possibility of their detection, and how this would provide information about the equation of state of dense matter.

    ↳ astro-ph.HEhep-phnucl-thIJMPE(2018)·33 citations
21. 21*

    Spectrum and structure of octet and decuplet baryons and their positive-parity excitations

    Chen Chen🇧🇷 · Gastao Krein🇧🇷 · Craig D. Roberts🇺🇸 · Sebastian M. Schmidt🇩🇪 · Jorge Segovia🇪🇸

    A continuum approach to the three valence-quark bound-state problem in quantum field theory, employing parametrisations of the necessary kernel elements, is used to compute the spectrum and Poincaré-covariant wave functions for all flavour-$SU(3)$ octet and decuplet baryons and their first positive-parity excitations. Such analyses predict the existence of nonpointlike, dynamical quark-quark (diquark) correlations within all baryons; and a uniformly sound description of the systems studied is obtained by retaining flavour-antitriplet--scalar and flavour-sextet--pseudovector diquarks. Thus constituted, the rest-frame wave function of every system studied is primarily $S$-wave in character; and the first positive-parity excitation of each octet or decuplet baryon exhibits the characteristics of a radial excitation. Importantly, every ground-state octet and decuplet baryon possesses a radial excitation. Hence, the analysis predicts the existence of positive-parity excitations of the $\Xi$, ${\Xi }^{\ast }$, $\Omega$ baryons, with masses, respectively (in GeV): 1.84(08), 1.89(04), 2.05(02). These states have not yet been empirically identified. This body of analysis suggests that the expression of emergent mass generation is the same in all $u$, $d$, $s$ baryons and, notably, that dynamical quark-quark correlations play an essential role in the structure of each one. It also provides the basis for developing an array of predictions that can be tested in new generation experiments.

    ↳ nucl-thhep-exhep-lathep-ph+1PRD(2019)·48 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.