Mon·Jan 29, 2018Monday·January 29, 2018

1. 01*

   QED Interference in Charge Asymmetry Near the Z Resonance at Future Electron-Positron Colliders

   Stanislaw Jadach🇵🇱 · Scott Yost🇺🇸

   The measurement of the charge asymmetry $A_{FB}(e^{-}{e}^{+}\to {\mu }^{-}{\mu }^{+})$ will play an important role at the high-luminosity circular electron-positron collider FCCee considered for construction at CERN. In particular, near the Z resonance, $\sqrt{s}\simeq M_Z\pm 3.5$ GeV, $A_{FB}$ will provide a very precise value of the pure electromagnetic coupling constant ${\alpha }_{QED}(M_Z)$, which is vitally important for overall tests of the Standard Model. For this purpose, $A_{FB}$ will be measured at the FCCee with an experimental error better than $\delta A_{FB}\simeq 3\cdot 10^{-5},$ at least a factor 100 more precisely than at past LEP experiments! The important question is whether the effect of interference between photon emission in the initial and final state can be removed from the $A_{FB}$ data at the same precision level using perturbative QED calculations. A first quantitative study of this problem is presented here, with the help of the KKMC program and a newly developed calculation based on soft photon resummation, matched with NLO and NNLO fixed-order calculations. It is concluded that a factor of 10 improvement with respect to the LEP era is obtained. We also present a clear indication that reducing the uncertainty of charge asymmetry near the Z peak due to IFI down to $\delta A_{FB}\simeq 3\cdot 10^{-5}$, i.e. the expected experimental precision at FCCee, is feasible.

   hep-phPRD(2019)·26 citations
2. 02*

   Singly Cabibbo-suppressed hadronic decays of ${\Lambda }_c^{+}$

   Hai-Yang Cheng🇹🇼 · Xian-Wei Kang🇹🇼 · Fanrong Xu🇨🇳

   We study singly Cabibbo-suppressed two-body hadronic decays of the charmed baryon ${\Lambda }_c^{+}$, namely, ${\Lambda }_c^{+}\to \Lambda K^{+},p{\pi }^0,p\eta ,n{\pi }^{+},{\Sigma }^0{K}^{+},{\Sigma }^{+}{K}^0$. We use the measured rate of ${\Lambda }_c^{+}\to p\varphi$ to fix the effective Wilson coefficient $a_2$ for naive color-suppressed modes and the effective number of color $N_c^{\mathrm{eff}}$. We rely on the current-algebra approach to evaluate $W$-exchange and nonfactorizable internal $W$-emission amplitudes, that is, the commutator terms for the $S$-wave and the pole terms for the $P$-wave. Our prediction for ${\Lambda }_c^{+}\to p\eta$ is in excellent agreement with the BESIII measurement. The $p\eta$ ($p{\pi }^0$) mode has a large (small) rate because of a large constructive (destructive) interference between the factorizable and nonfactorizable amplitudes for both $S$- and $P$-waves. Some of the SU(3) relations such as $M({\Lambda }_c^{+}\to n{\pi }^{+})=\sqrt{2}M({\Lambda }_c^{+}\to p{\pi }^0)$ derived under the assumption of sextet dominance are not valid for decays with factorizable terms. Our calculation indicates that the branching fraction of ${\Lambda }_c^{+}\to n{\pi }^{+}$ is about 3.5 times larger than that of ${\Lambda }_c^{+}\to p{\pi }^0$. Decay asymmetries are found to be negative for all singly Cabibbo-suppressed modes and range from $-0.56$ to $-0.96$.

   hep-phhep-exPRD(2018)·97 citations
3. 03*

   Masses of doubly heavy-quark baryons in an extended chromomagnetic model

   Xin-Zhen Weng🇨🇳 · Xiao-Lin Chen🇨🇳 · Wei-Zhen Deng🇨🇳

   We extend the chromomagnetic model by further considering the effect of color interaction. The effective mass parameters between quark pairs ($m_{qq}$ or $m_{q\bar{q}}$) are introduced to account both the effective quark masses and the color interaction between the two quarks. Using the experimental masses of hadrons, the quark pair parameters are determined between the light quark pairs and the light-heavy quark pairs. Then the parameters of heavy quark pairs ($cc$, $cb$, $bb$) are estimated based on simple quark model assumption. We calculate all masses of doubly and triply heavy-quark baryons. The newly discovered doubly charmed baryon ${\Xi }_{cc}$ fits into the model with an error of 12 MeV.

   hep-phPRD(2018)·69 citations
4. 04*

   Revisiting $D_{s0}^{\ast }(2317)$ as a $0^{+}$ tetraquark state from QCD sum rules

   Jian-Rong Zhang🇨🇳

   Stimulated by the renewed observation of $D_{s0}^{\ast }(2317)$ signal and its updated mass value $2318.3\pm 1.2\pm 1.2\text{mbox}MeV/c^2$ in the process $e^{+}{e}^{-}\to D_s^{\ast +}{D}_{s0}^{\ast }(2317{)}^{-}+c.c.$ by BESIII Collaboration, we devote to reinvestigate $D_{s0}^{\ast }(2317)$ as a $0^{+}$ tetraquark state from QCD sum rules. Technically, four different possible currents are adopted and high condensates up to dimension $12$ are included in the operator product expansion (OPE) to ensure the quality of QCD sum rule analysis. In the end, we obtain the mass value $2.37_{-0.36}^{+0.50}\text{mbox}GeV$ with the factorization parameter $\rho =1$ (or $2.23_{-0.24}^{+0.78}\text{mbox}GeV$ with $\rho =3$) for the scalar-scalar current, which agrees well with the experimental data of $D_{s0}^{\ast }(2317)$ and could support its explanation as a $0^{+}$ scalar-scalar tetraquark state. The final result for the axial-axial configuration is calculated to be $2.51_{-0.43}^{+0.61}\text{mbox}GeV$ with $\rho =1$ (or $2.52_{-0.52}^{+0.76}\text{mbox}GeV$ with $\rho =3$), which is still consistent with the mass of $D_{s0}^{\ast }(2317)$ considering the uncertainty, and then the possibility of $D_{s0}^{\ast }(2317)$ as a axial-axial tetraquark state can not be excluded. For the pseudoscalar-pseudoscalar and the vector-vector cases, their unsatisfactory OPE convergence makes that it is of difficulty to find rational work windows to further acquire hadronic masses.

   hep-phhep-exPLB(2019)·24 citations
5. 05*

   Strong decays of higher charmonium states into open-charm meson pairs

   Long-Cheng Gui🇨🇳 · Long-Sheng Lu🇨🇳 · Qi-Fang Lü🇨🇳 · Xian-Hui Zhong🇨🇳 · Qiang Zhao🇨🇳

   The open-charm strong decays of higher charmonium states up to the mass of the $6P$ multiplet are systematically studied in the ${}^3{P}_0$ model. The wave functions of the initial charmonium states are calculated in the linear potential (LP) and screened potential (SP) quark model. The decay widths for most of the well-established charmonium states above the open-charm thresholds can be reasonably described. By comparing our quark model calculations with the experimental observations we also discuss the nature of some of the newly observed charmonium-like states. It is found that (i) the $\psi (4415)$ may favor the $\psi (4S)$ or ${\psi }_1(3D)$ assignment. There may exist two highly overlapping vector charmonium states around 4.4 GeV; (ii) In the LP model the $J^{PC}=1^{--}$ $Y(4660)$ resonance and the $J^{PC}=0^{++}$ $X(4500)$ resonance may be assigned as the $\psi (5S)$ and ${\chi }_{c0}(4P)$, respectively; (iii) The newly observed state $X^{\ast }(3860)$ can be assigned as the ${\chi }_{c0}(2P)$ state with a narrow width of about $30$ MeV; (iv) It seems to be difficult to accommodate the $X(4140)$ and $X(4274)$ states in the same potential model as excited ${\chi }_{c1}$ states. (v) The $X(3940)$ resonance can be assigned as the ${\eta }_c(3S)$ state; (vi) The vector charmonium-like states $Y(4230/4260,4360)$ and scalar $X(4700)$ cannot be described by any conventional charmonium states self-consistently in our model.

   hep-phhep-exPRD(2018)·51 citations
6. 06*

   Gamma-ray spectral modulations of Galactic pulsars caused by photon-ALPs mixing

   Jhilik Majumdar🇩🇪 · Francesca Calore🇫🇷 · Dieter Horns🇩🇪

   Well-motivated extensions of the standard model predict ultra-light and fundamental pseudo-scalar particles (e.g., axions or axion-like particles: ALPs). Similarly to the Primakoff-effect for axions, ALPs can mix with photons and consequently be searched for in laboratory experiments and with astrophysical observations. Here, we search for energy-dependent modulations of high-energy gamma-ray spectra that are tell-tale signatures of photon-ALPs mixing. To this end, we analyze the data recorded with the Fermi -LAT from Galactic pulsars selected to have a line of sight crossing spiral arms at a large pitch angle. The large-scale Galactic magnetic field traces the shape of spiral arms, such that a sizable photon-ALP conversion probability is expected for the sources considered. In nine years of Fermi -LAT data, we detect significant spectral features in the selected source-sample consistent with photon-ALPs oscillation with a combined statistical significance of 5.52 {\sigma} . Notably, sources with neighboring lines of sight share similar spectral features. From a common fit to all sources, we determine the most-likely parameters for mass $m_a$ and coupling $g_{a\gamma \gamma }$ to be $m_a=(3.6\begin{array}{c}+0.5_{stat.}\\ -0.2_{stat.}\end{array}\pm 0.2_{syst.})$ neV and $g_{a\gamma \gamma }=(2.3\begin{array}{c}+0.3_{stat.}\\ -0.4_{stat.}\end{array}\pm 0.4_{syst.})\times 10^{-10}$ GeV${}^{-1}$. In the error budget, we consider instrumental effects, scaling of the adopted Galactic magnetic field model ($\pm 20\%$), and uncertainties on the distance of individual sources. We note that an astrophysical interpretation of the detected modulation is not obvious.

   hep-phastro-ph.HEJCAP(2018)·48 citations
7. 07*

   Higgs alignment from extended supersymmetry

   Karim Benakli🇫🇷 · Mark D. Goodsell🇫🇷 · Sophie L. Williamson🇫🇷

   We consider the effective type-II Two-Higgs doublet model originating from Dirac gaugino models with extended supersymmetry in the gauge sector, which is automatically aligned in the simplest realisations. We show that raising the scale at which the extended supersymmetry is manifest and including quantum corrections actually improves the alignment. Using an effective field theory approach including new threshold corrections and two-loop RGEs, plus two-loop corrections to the Higgs mass in the low-energy theory, we study the implications from the Higgs mass and other experimental constraints on the scale of superpartners. We contrast the results of the minimal Dirac gaugino model, where alignment is automatic, with the hMSSM and the MRSSM, where it is not, also providing an hMSSM-inspired analysis for the new models.

   hep-phEPJC(2018)·41 citations
8. 08*

   Neutrino electromagnetic properties: a window to new physics - II

   Alexander Studenikin🇷🇺

   There is merely a short note on the selected issues of neutrino electromagnetic properties with focus on effects of new physics. The meaning of "new physics" is twofold: 1) a massive neutrino have nonzero electromagnetic properties that can be considered as manifestation of new physics beyond the Standard Model, and 2) in studies of neutrinos electromagnetic interactions new effects are predicted that can lead to new phenomena accessible for observations.

   hep-phPoS(2017)·11 citations
9. 09*

   On possible application of spin light of neutrino in astrophysics

   Alexander Grigoriev🇷🇺 · Alexey Lokhov🇷🇺 · Alexander Studenikin🇷🇺 · Alexei Ternov🇷🇺

   The $spin$ $light$ $of$ $neutrino$ ($SL\nu$) is a phenomenon of electromagnetic radiation by a massive neutrino moving in external media that is originated owing to neutrino magnetic moment. In this short paper we note on the importance of this effect in the light of its connection with the neutrino magnetic moment, recap its basic properties in dense matter and give some general criteria for its best efficiency in nature. On this basis we propose a set of possible astrophysical environments where the $SL\nu$ can be manifested in principle.

   hep-phPoS(2018)·0 citations
10. 10*

    Neutrino quantum decoherence due to entanglement with magnetic field

    Konstantin Stankevich🇷🇺 · Alexander Studenikin🇷🇺

    The phenomena of neutrino oscillations emerges due to coherent superposition of different neutrino states. The entanglement of neutrinos with its environment can lead to a suppression of neutrino oscillations. The master equation for neutrino evolution in a magnetic field is derived taking into account the entanglement with a magnetic field.

    hep-phPoS(2018)·6 citations
11. 11*

    Neutrino motion and spin oscillations in magnetic field and matter currents

    Artem Popov🇷🇺 · Pavel Pustoshny🇷🇺 · Alexander Studenikin🇷🇺

    A brief review of a neutrino oscillations effect in an external magnetic field and matter currents is given. An ultra-relativistic neutrino propagation in moving external media is investigated. We have found a new spin operator which commutes with the corresponding Hamiltonian, exact wave functions and energy spectrum are obtained.

    hep-phPoS(2018)·0 citations
12. 12*

    Heavy Neutral Leptons at FASER

    Felix Kling🇺🇸 · Sebastian Trojanowski🇺🇸

    We study the prospects for discovering heavy neutral leptons at ForwArd Search ExpeRiment (FASER), the newly proposed detector at the LHC. Previous studies showed that a relatively small detector with ~10 m length and ~1 m cross sectional area can probe large unconstrained parts of parameter space for dark photons and dark Higgs bosons. In this work we show that FASER will also be sensitive to heavy neutral leptons that have mixing angles with the active neutrinos that are up to an order of magnitude lower than current bounds. In particular, this is true for heavy neutral leptons produced dominantly in $B$-meson decays, in which case FASER's discovery potential is comparable to the proposed SHiP detector. We also illustrate how the search for heavy neutral leptons at FASER will be complementary to ongoing searches in high-$p_T$ experiments at the LHC and can shed light on the nature of dark matter and the process of baryogenesis in the early Universe.

    hep-phPRD(2018)·177 citations
13. 13*

    Fully Constrained Majorana Neutrino Mass Matrices Using $\Sigma (72\times 3)$

    R. Krishnan🇬🇧 · P. F. Harrison🇬🇧 · W. G. Scott🇬🇧

    In 2002, two neutrino mixing ansatze having trimaximally-mixed middle (${\nu }_2$) columns, namely tri-chi-maximal mixing ($\text{T}\chi \text{M}$) and tri-phi-maximal mixing ($\text{T}\varphi \text{M}$), were proposed. In 2012, it was shown that $\text{T}\chi \text{M}$ with $\chi =\pm \frac{\pi }{16}$ as well as $\text{T}\varphi \text{M}$ with $\varphi =\pm \frac{\pi }{16}$ leads to the solution, ${\sin }^2{\theta }_{13}=\frac{2}{3}{\sin }^2\frac{\pi }{16}$, consistent with the latest measurements of the reactor mixing angle, ${\theta }_{13}$. To obtain $\text{T}\chi {\text{M}}_{(\chi =\pm \frac{\pi }{16})}$ and $\text{T}\varphi {\text{M}}_{(\varphi =\pm \frac{\pi }{16})}$, the type~I see-saw framework with fully constrained Majorana neutrino mass matrices was utilised. These mass matrices also resulted in the neutrino mass ratios, $m_1:m_2:m_3=\frac{\left(2+\sqrt{2}\right)}{1+\sqrt{2(2+\sqrt{2})}}:1:\frac{\left(2+\sqrt{2}\right)}{-1+\sqrt{2(2+\sqrt{2})}}$. In this paper we construct a flavour model based on the discrete group $\Sigma (72\times 3)$ and obtain the aforementioned results. A Majorana neutrino mass matrix (a symmetric $3\times 3$ matrix with 6 complex degrees of freedom) is conveniently mapped into a flavon field transforming as the complex 6 dimensional representation of $\Sigma (72\times 3)$. Specific vacuum alignments of the flavons are used to arrive at the desired mass matrices.

    hep-phEPJC(2018)·7 citations
14. 14*

    N* Structure and Strong QCD

    Craig D. Roberts🇺🇸

    In attempting to match QCD with Nature, it is necessary to confront the many complexities of strong, nonlinear dynamics in relativistic quantum field theory, e.g. the loss of particle number conservation, the frame and scale dependence of the explanations and interpretations of observable processes, and the evolving character of the relevant degrees-of-freedom. The peculiarities of QCD ensure that it is also the only known fundamental theory with the capacity to sustain massless elementary degrees-of-freedom, gluons and quarks; and yet gluons and quarks are predicted to acquire mass dynamically so that the only massless systems in QCD are its composite Nambu-Goldstone bosons. All other everyday bound states possess nuclear-size masses, far in excess of anything that can directly be tied to the Higgs boson. These observations highlight fundamental questions within the Standard Model: what is the source of the mass for the vast bulk of visible matter in the Universe, how is its appearance connected with confinement; how is this mass distributed within hadrons and does the distribution differ from one hadron to another? This contribution sketches insights drawn using modern methods for the continuum bound-state problem in QCD, and how they have been informed by empirical information on the hadron spectrum and nucleon-to-resonance transition form factors.

    ↳ nucl-thhep-lathep-phnucl-exFew Body Syst.(2018)·23 citations
15. 15*

    First Cosmological Constraint on the Effective Theory of Dark Matter-Proton Interactions

    Kimberly K. Boddy🇺🇸 · Vera Gluscevic🇺🇸

    We obtain the first cosmological constraints on interactions between dark matter and protons within the formalism of nonrelativistic effective field theory developed for direct detection. For each interaction operator in the effective theory, parametrized by different powers of the relative velocity of the incoming particles, we use the Planck 2015 cosmic microwave background (CMB) temperature, polarization, and lensing anisotropy to set upper limits on the scattering cross section for all dark matter masses above 15 keV. We find that for interactions associated with a stronger dependence on velocity, dark matter and baryons stay thermally coupled for longer, but the interaction strengths are suppressed at the low temperatures relevant for Planck observations and are thus less constrained. At the same time, cross sections with stronger velocity dependencies are more constrained in the limit of small dark matter mass. In all cases, the effect of dark matter-proton scattering is most prominent on small scales in the CMB power spectra and in the matter power spectrum, and we thus expect substantial improvement over the current limits with data from ground-based CMB experiments and galaxy surveys.

    ↳ astro-ph.COhep-phPRD(2018)·131 citations
16. 16*

    Microscopically-based energy density functionals for nuclei using the density matrix expansion: Full optimization and validation

    R. Navarro Perez🇺🇸 · N. Schunck🇺🇸 · A. Dyhdalo🇺🇸 · R.J. Furnstahl🇺🇸 · S.K. Bogner🇺🇸

    We seek to obtain a usable form of the nuclear energy density functional that is rooted in the modern theory of nuclear forces. We thus consider a functional obtained from the density matrix expansion of local nuclear potentials from chiral effective field theory. We propose a parametrization of this functional carefully calibrated and validated on selected ground-state properties that is suitable for large-scale calculations of nuclear properties. The first component of this functional is a non-local functional of the density and corresponds to the direct part (Hartree term) of the expectation value of local chiral potentials on a Slater determinant. A second component is a local functional of the density and is obtained by applying the density matrix expansion to the exchange part (Fock term) of the expectation value of the local chiral potential. We apply the UNEDF2 optimization protocol to determine the coupling constants of this energy functional. We obtain a set of microscopically-constrained functionals for local chiral potentials from leading-order up to next-to-next-to-leading order with and without three-body forces and contributions from $\Delta$ excitations. These functionals are validated on the calculation of nuclear and neutron matter, nuclear mass tables, single-particle shell structure in closed-shell nuclei and the fission barrier of ${}^{240}$Pu. Quantitatively, they perform noticeable better than the more phenomenological Skyrme functionals. The inclusion of higher-order terms in the chiral perturbation expansion seems to produce a systematic improvement in predicting nuclear binding energies. This result is especially promising since all the fits have been performed at the single reference level of the energy density functional approach, where important collective correlations such as center-of-mass correction have not been taken into account yet.

    ↳ nucl-thhep-phnucl-exPRC(2018)·47 citations
17. 17*

    New universal attractor in nonmininally coupled gravity: Linear inflation

    Antonio Racioppi🇪🇪

    Once quantum corrections are taken into account, the strong coupling limit of the $\xi$-attractor models (in metric gravity) might depart from the usual Starobinsky solution and move into linear inflation. Furthermore, it is well known that the metric and Palatini formulations of gravity lead to different inflationary predictions in presence of non-minimally couplings between gravity and the inflaton. In this letter we show that for a certain class of non-minimally coupled models, loop corrections will lead to a linear inflation attractor regardless of the adopted gravity formulation.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2018)·85 citations
18. 18*

    Neutrinos, supernovae, and the origin of the heavy elements

    Yong-Zhong Qian🇺🇸

    Stars of ~8-100 solar masses end their lives as core-collapse supernovae (SNe). In the process they emit a powerful burst of neutrinos, produce a variety of elements, and leave behind either a neutron star or a black hole. The wide mass range for SN progenitors results in diverse neutrino signals, explosion energies, and nucleosynthesis products. A major mechanism to produce nuclei heavier than iron is rapid neutron capture, or the r process. This process may be connected to SNe in several ways. A brief review is presented on current understanding of neutrino emission, explosion, and nucleosynthesis of SNe.

    ↳ astro-ph.HEastro-ph.SRhep-phnucl-thSCPMA(2018)·6 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.