Thu·Aug 22, 2019Thursday·August 22, 2019

1. 01*

   The W and Z scattering as a probe of physics beyond the Standard Model: Effective Field Theory approach

   Paweł Kozów🇵🇱

   In this work the vector boson scattering process is investigated through the reaction $pp\to 2\mathrm{jets}+W^{\ast }{W}^{\ast }\to 2\mathrm{jets}+l{\nu }_l{l}^{\prime }{\nu }_l^{\prime }$, where $W^{\ast }$ denote in general off-shell $W^{+}$, in the EFT approach with the HL-LHC and HE-LHC experiments in mind. We have investigated the discovery potential of certain classes of the EFT "models" of both the SMEFT and HEFT bases with the particular emphasis on using the EFT "models" in their region of validity. A novel method has been proposed for determining the discovery regions of physics beyond the SM, described by the EFT "models". Independent of the basis chosen, the discovery regions are found to be non-empty. We then compare differences in experimental signatures between SMEFT and HEFT, which is an important step for distinguishing between the two hypotheses in the future data. Finally, we investigated what the effect on the discovery regions is when increasing the $pp$ collision energy.

   hep-ph3 citations
2. 02*

   Magnetic fields in heavy ion collisions: flow and charge transport

   Gabriele Inghirami🇫🇮 · Mark Mace🇫🇮 · Yuji Hirono🇰🇷 · Luca Del Zanna🇮🇹 · Dmitri E. Kharzeev🇺🇸 · Marcus Bleicher🇩🇪

   At the earliest times after a heavy-ion collision, the magnetic field created by the spectator nucleons will generate an extremely strong, albeit rapidly decreasing in time, magnetic field. The impact of this magnetic field may have detectable consequences, and is believed to drive anomalous transport effects like the Chiral Magnetic Effect (CME). We detail an exploratory study on the effects of a dynamical magnetic field on the hydrodynamic medium created in the collisions of two ultrarelativistic heavy-ions, using the framework of numerical ideal MagnetoHydroDynamics (MHD) with the ECHO-QGP code. In this study, we consider a magnetic field captured in a conducting medium, where the conductivity can receive contributions from the electromagnetic conductivity $\sigma$ and the chiral magnetic conductivity ${\sigma }_{\chi }$. We first study the elliptic flow of pions, which we show is relatively unchanged by the introduction of a magnetic field. However, by increasing the magnitude of the magnetic field, we find evidence for an enhancement of the elliptic flow in peripheral collisions. Next, we explore the impact of the chiral magnetic conductivity on electric charges produced at the edges of the fireball. This initial ${\sigma }_{\chi }$ can be understood as a long-wavelength effective description of chiral fermion production. We then demonstrate that this chiral charge, when transported by the MHD medium, produces a charge dipole perpendicular to the reaction plane which extends a few units in rapidity. Assuming charge conservation at the freeze-out surface, we show that the produced charge imbalance can have measurable effects on some experimental observables, like $v_1$ or $⟨\sin \varphi ⟩$. This demonstrates the ability of a MHD fluid to transport the signature of the initial chiral magnetic fields to late times.

   hep-phnucl-exnucl-thEPJC(2020)·117 citations
3. 03*

   Prime-Index Parametrization for Total Neutrino-Nucleon Cross Sections and {\it{pp}} Cross Sections

   Ali R. Fazely🇺🇸

   A prime number based parametrization for total neutrino-nucleon cross section is presented. The method employs the relation between prime numbers and their indices to reproduce neutrino cross sections for neutrino energies from the $MeV$ to the $PeV$ regions where experimental data are available. This prime-index relation provides estimates of the neutrino-nucleon cross sections valid across many decades of neutrino energy scales. The $PeV$ data are from the recently published astrophysical ${\nu }_{\mu }+{\bar{\nu }}_{\mu }$ rates in the IceCube detector as well as neutrino-nucleon cross section measurements. A similar method has been employed for high energy $pp$ cross sections which explains the $(\ln s{)}^2$ parametrization first proposed by Heisenberg.

   hep-phJ.Phys.G(2019)·0 citations
4. 04*

   Heavy quarkonia properties from a hard-wall confinement potential model with conformal symmetry perturbing effects

   Ahmed Al-Jamel🇯🇴

   Heavy $c\bar{c}$ and $b\bar{b}$ quarkonia are considered as systems confined within a hard-wall potential shaped after a linear combination of a cotangent-- with a square co-secant function. Wave functions and energy spectra are then obtained in closed forms in solving by the Nikiforov-Uvarov method the associated radial Schrödinger equation in the presence of a centrifugal term. The interest in this potential is that in one parametrization it can account for a conformal symmetry of the strong interaction, and in another for its perturbation, a reason for which we here employ it to study status of conformal symmetry in the heavy flavor sector. The resulting predictions on heavy quarkonia mass spectra and root mean square radii are compared with the available experimental data, as well as with predictions by other theoretical approaches. We observe that a relatively small conformal symmetry perturbing term in the potential suffices to achieve good agreement with data.

   hep-phMod.Phys.Lett.A(2019)·11 citations
5. 05*

   Higgs lepton flavor violating decays in Two Higgs Doublet Models

   Avelino Vicente🇪🇸

   The discovery of a non-zero rate for a lepton flavor violating decay mode of the Higgs boson would definitely be an indication of New Physics. We review the prospects for such signal in Two Higgs Doublet Models, in particular for Higgs boson decays into $\tau \mu$ final states. We will show that this scenario contains all the necessary ingredients to provide large flavor violating rates and still be compatible with the stringent limits from direct searches and low-energy flavor experiments.

   hep-phhep-exFront.in Phys.(2019)·29 citations
6. 06*

   The ${\gamma }^{\ast }{\gamma }^{\ast }\to {\eta }_c(1S,2S)$ transition form factors for spacelike photons

   Izabela Babiarz🇵🇱 · Victor P. Goncalves🇧🇷 · Roman Pasechnik🇸🇪 · Wolfgang Schäfer🇵🇱 · Antoni Szczurek🇵🇱

   We derive the light-front wave function (LFWF) representation of the ${\gamma }^{\ast }{\gamma }^{\ast }\to {\eta }_c(1S),{\eta }_c(2S)$ transition form factor $F(Q_1^2,Q_2^2)$ for two virtual photons in the initial state. For the LFWF, we use different models obtained from the solution of the Schrödinger equation for a variety of $c\bar{c}$ potentials. We compare our results to the BaBar experimental data for the ${\eta }_c(1S)$ transition form factor, for one real and one virtual photon. We observe that the onset of the asymptotic behaviour is strongly delayed and discuss applicability of the collinear and/or massless limit. We present some examples of two-dimensional distributions for $F(Q_1^2,Q_2^2)$. A factorization breaking measure is proposed and factorization breaking effects are quantified and shown to be almost model independent. Factorization is shown to be strongly broken, and a scaling of the form factor as a function of ${\bar{Q}}^2=(Q_1^2+Q_2^2)/2$ is obtained.

   hep-phPRD(2019)·30 citations
7. 07*

   Effective Field Theory of Gravity to All Orders

   Maximilian Ruhdorfer🇩🇪 · Javi Serra🇩🇪 · Andreas Weiler🇩🇪

   We construct the general effective field theory of gravity coupled to the Standard Model of particle physics, which we name GRSMEFT. Our method allows the systematic derivation of a non-redundant set of operators of arbitrary dimension with generic field content and gravity. We explicitly determine the pure gravity EFT up to dimension ten, the EFT of a shift-symmetric scalar coupled to gravity up to dimension eight, and the operator basis for the GRSMEFT up to dimension eight. Extensions to all orders are straightforward.

   hep-phgr-qchep-thJHEP(2020)·115 citations
8. 08*

   Neutrino mass model with a modular $S_4$ symmetry

   Hiroshi Okada🇰🇷 · Yuta Orikasa🇨🇿

   We propose a predictive lepton model under a modular $S_4$ symmetry, where the neutrino mass matrix arises from a radiative seesaw at one-loop level. The tree-level mass matrix is forbidden by well-assigned modular weights, which also play an important role in stabilizing dark matter candidate due to a remnant $Z_2$ symmetry even after breaking the modular symmetry. Supposing three families of the Majorana neutrinos, right-handed charged-leptons and left-handed charged-leptons to be embedded respectively into singlet, doublet, and triplet under $S_4$, we obtain the predictive mass matrices in the normal hierarchy. Then, we show our numerical results such as phases, mixings, and neutrino masses, applying ${\chi }^2$ analysis. We also demonstrate two sample points, imposing on minimizing ${\chi }^2$ and best fit value of ${\delta }_{CP}^{\ell }$ of $195^{\circ }$.

   hep-ph65 citations
9. 09*

   MeV-scale reheating temperature and thermalization of oscillating neutrinos by radiative and hadronic decays of massive particles

   Takuya Hasegawa🇯🇵 · Nagisa Hiroshima🇯🇵 · Kazunori Kohri🇯🇵 · Rasmus S. L. Hansen🇩🇪 · Thomas Tram🇩🇰 · Steen Hannestad🇩🇰

   From a theoretical point of view, there is a strong motivation to consider an MeV-scale reheating temperature induced by long-lived massive particles with masses around the weak scale, decaying only through gravitational interaction. In this study, we investigate lower limits on the reheating temperature imposed by big-bang nucleosynthesis assuming both radiative and hadronic decays of such massive particles. For the first time, effects of neutrino self-interactions and oscillations are taken into account in the neutrino thermalization calculations. By requiring consistency between theoretical and observational values of light element abundances, we find that the reheating temperature should conservatively be $T_{\mathrm{RH}}\gtrsim 1.8$ MeV in the case of the 100% radiative decay, and $T_{\mathrm{RH}}\gtrsim$ 4-5 MeV in the case of the 100% hadronic decays for particle masses in the range of 10 GeV to 100 TeV.

   hep-phastro-ph.COJCAP(2019)·415 citations
10. 10*

    Quest for new physics using astrophysical neutrino flavor in IceCube

    Carlos A. Argüelles🇺🇸 · Kareem Farrag🇬🇧 · Teppei Katori🇬🇧 · Shivesh Mandalia (for the IceCube Collaboration)🇬🇧

    We have detected astrophysical neutrinos in IceCube that can be used to probe astrophysical sources at ultra high scales. Here we report a search for anomalous space time effects using astrophysical neutrino flavor data in IceCube. New effective operators are introduced to drive non-standard neutrino flavor mixing which modify the flavor ratios compared to standard cases. Using the High Energy Starting Events sample (HESE) 7.5-year data for this analysis, we found no evidence of such flavor anomalies. However, we are expecting to set limits from this new approach which goes far beyond any known techniques. Importantly, we achieve the necessary precision to probe new physics using neutrino flavor expected by Planck scale theories.

    ↳ astro-ph.HEhep-exhep-phPoS(2020)·2 citations
11. 11*

    Consistent large-scale shell-model analysis of the two-neutrino $\beta \beta$ and single $\beta$ branchings in ${}^{48}\mathrm{Ca}$ and ${}^{96}\mathrm{Zr}$

    Joel Kostensalo🇫🇮 · Jouni Suhonen🇫🇮

    Two-neutrino double-beta-decay matrix elements $M_{2\nu }$ and single beta-decay branching ratios were calculated for ${}^{48}$Ca and ${}^{96}$Zr in the interacting nuclear shell model using large single-particle valence spaces with well-tested two-body Hamiltonians. For ${}^{48}$Ca the matrix element $M_{2\nu }=0.0511$ is obtained, which is 5.5\% smaller than the previously reported value of 0.0539. For ${}^{96}$Zr this work reports the first large-scale shell-model calculation of the nuclear matrix element, yielding a value $M_{2\nu }=0.0747$ with extreme single-state dominance. If the scenario where the first $1^{+}$ state in ${}^{96}$Nb is at 694.6 keV turns out to be correct, the matrix element is increased to 0.0854. These matrix elements, combined with the available $\beta \beta$-decay half-life data, yield effective values of the weak axial coupling which in turn are used to produce in a consistent way the $\beta$-decay branching ratios of $(7.5\pm 2.8)$ % for ${}^{48}$Ca and $(18.4\pm 0.09)$ % for ${}^{96}$Zr. These are larger than obtained in previous studies, implying that the detection of the $\beta$-decay branches could be possible in dedicated experiments sometime in the (near) future.

    ↳ nucl-thhep-phPLB(2020)·25 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.