Mon·Apr 15, 2019Monday·April 15, 2019

1. 01*

   Confronting pentaquark photoproduction with new LHCb observations

   Xu Cao🇨🇳 · Jian-ping Dai🇨🇳

   The newly measurement of production fractions of $P_c$ states by LHCb collaboration have put restriction on their branching ratios of $J/\psi p$ decay, thus constraining their photoproduction in $\gamma p\to J/\psi p$ reaction. We show the tension between LHCb results and the current experiments in search of $P_c$ photoproduction. We also find that the present information of branching ratios of $P_c\to J/\psi p$ has already confronted sharply with the models which study the nature of $P_c$.

   hep-phPRD(2019)·69 citations
2. 02*

   Geometrical contribution to neutrino mass matrix

   Subhasish Chakrabarty🇮🇳 · Amitabha Lahiri🇮🇳

   The dynamics of fermions on curved spacetime requires a spin connection, which contains a part called contorsion, an auxiliary field without dynamics but fully expressible in terms of the axial current density of fermions. Its effect is the appearance of a quartic interaction of all fermions in the action, leading to a nonlinear Dirac equation involving all fermions present. Noting that left and right-chiral fermions may couple to contorsion by different strengths, we show that all fermions gain an effective mass when propagating through fermionic matter. This may have an observable effect on neutrino oscillations. In particular we find that different neutrino flavors can mix even if they have zero rest mass in vacuum, without requiring fields beyond the Standard Model.

   hep-phgr-qcEPJC(2019)·20 citations
3. 03*

   Study of the electromagnetic Dalitz decays $\psi ({\rm Y})\to {\eta }_c({\eta }_b)l^{+}{l}^{-}$

   Li-Min Gu🇨🇳 · Hai-Bo Li🇨🇳 · Xin-Xin Ma🇨🇳 · Mao-Zhi Yang🇨🇳

   We study the electromagnetic Dalitz (EM) decays, $\psi \to {\eta }_c{l}^{+}{l}^{-}$ and ${\rm Y}\to {\eta }_b{l}^{+}{l}^{-}$ ($l=e$ or $\mu$), in which the lepton pair comes from the virtual photon emitted by the M1 transition from $c\bar{c}$ ($b\bar{b}$) spin triplet state to the spin singlet state. We estimate the partial width of $\psi ({\rm Y})\to {\eta }_c({\eta }_b)l^{+}{l}^{-}$, based on the simple pole approximation. Besides, based on different QCD models, the partial width of $\psi ({\rm Y})\to {\eta }_c({\eta }_b)\gamma$ is determined.

   hep-phPRD(2019)·16 citations
4. 04*

   Low-scale seesaw from neutrino condensation

   Claudio Dib🇨🇱 · Sergey Kovalenko🇨🇱 · Ivan Schmidt🇨🇱 · Adam Smetana🇨🇿

   Knowledge of the mechanism of neutrino mass generation would help understand a lot more about Lepton Number Violation (LNV), the cosmological evolution of the Universe, or the evolu tion of astronomical objects. Here we propose a verifiable and viable extension of the Standard model for neutrino mass generation, with a low-scale seesaw mechanism via LNV condensation in the sector of sterile neutrinos. To prove the concept, we analyze a simplified model of just one single family of elementary particles and check it against a set of phenomenological constraints coming from electroweak symmetry breaking, neutrino masses, leptogenesis and dark matter. The model predicts (i) TeV scale quasi-degenerate heavy sterile neutrinos, suitable for leptogenesis with resonant enhancement of the CP asymmetry, (ii) a set of additional heavy Higgs bosons whose existence can be challenged at the LHC, (iii) an additional light and sterile Higgs scalar which is a candidate for decaying warm dark matter, and (iv) a majoron. Since the model is based on simple and robust principles of dynamical mass generation, its parameters are very restricted, but remarkably it is still within current phenomenological limits.

   hep-phNPB(2020)·6 citations
5. 05*

   Left-Right Supersymmetry as the Origin of Flavor Physics

   Sean Fraser🇪🇪 · Emidio Gabrielli🇮🇹 · Carlo Marzo🇪🇪 · Luca Marzola🇪🇪 · Martti Raidal🇪🇪

   We propose a new framework for the observed flavor hierarchy and mixing based on left-right supersymmetry. The model contains the most minimal Higgs sector consisting only of gauge doublets which forbid the standard model Yukawa couplings. New mediator fields then connect the left- and right-chiral fermion sectors and result in effective tree level Yukawa couplings for the third generation charged fermions. The remaining fermions, including all neutrinos, acquire effective Yukawa couplings sourced by the supersymmetry breaking sector at loop level. We predict new TeV range scalars, as well as heavier fermions and vector bosons, that can be discovered at the LHC and future colliders.

   hep-phPRD(2019)·0 citations
6. 06*

   NLO corrections to $h\to b\bar{b}$ decay in SMEFT

   Jonathan M. Cullen🇬🇧 · Benjamin D. Pecjak🇬🇧 · Darren J. Scott🇳🇱

   We calculate the full set of next-to-leading order (NLO) corrections to $h\to b\bar{b}$ decay in the dimension-6 Standard Model Effective Field Theory (SMEFT). Our calculation forms the basis for precision studies of this decay mode in effective field theory, providing analytic and numerical results for contributions of the 45 dimension-6 operators appearing at NLO. On the technical side, we discuss several complications in NLO SMEFT computations which have not yet been addressed in the literature. These include subtleties in Higgs-$Z$ mixing, electric charge renormalization, and especially the treatment of tadpoles in SMEFT. In particular, we highlight the role of decoupling relations in eliminating potentially large tadpole corrections to the decay rate in hybrid renormalization schemes which employ the $\overline{MS}$~scheme for some Standard Model parameters (such as the $b$-quark mass and electric charge) and the on-shell scheme for others.

   hep-phJHEP(2019)·49 citations
7. 07*

   $d^{\ast }(2380)$ and its partners in a diquark model

   Pan-Pan Shi🇨🇳 · Fei Huang🇨🇳 · Wen-Ling Wang🇨🇳

   The purpose of the present study was to explore the possibility of accommodating the $d^{\ast }(2380)$ and its flavor SU(3) partners in a diquark model. Proposing that $d^{\ast }(2380)$ is composed of three vector diquarks, its mass is calculated by use of an effective Hamiltonian approach and its decay width is estimated by considering the effects of quark tunneling from one diquark to the others and the decays of the subsequent two-baryon bound state. Both the obtained mass and decay width of $d^{\ast }(2380)$ are in agreement with the experimental data, with the unexpected narrow decay width being naturally explained by the large tunneling suppression of a quark between a pair of diquarks. The masses and decay widths of the flavor SU(3) partners of $d^{\ast }(2380)$ are also predicated within the same diquark scenario.

   ↳ nucl-thhep-exhep-phnucl-exEPJC(2019)·18 citations
8. 08*

   Cancellation of One-loop Corrections to Scalar Masses in Yang-Mills Theory with Flux Compactification

   Takuya Hirose🇯🇵 · Nobuhito Maru🇯🇵

   We calculate one-loop corrections to the mass for the zero mode of scalar field in a six-dimensional Yang-Mills theory compactified on a torus with magnetic flux. It is shown that these corrections are exactly cancelled thanks to a shift symmetry under the translation in extra spaces. This result is expected from the fact that the zero mode of scalar field is a Nambu-Goldstone boson of the translational invariance in extra spaces.

   ↳ hep-thhep-phJHEP(2019)·19 citations
9. 09*

   Comment on the X(3915) nonstandard hadron candidate

   Stephen Lars Olsen🇨🇳

   I review the experimental evidence for the $X(3915)$, the candidate nonstandard meson associated with $\omega J\psi$ resonance-like peaks in $B\to K\omega J\psi$ and $\gamma \gamma \to \omega J\psi$ near $M(\omega J\psi )=3920$~MeV, and address the conjecture that it can be identified as the ${\chi }_{c2}^{\prime }$, the radial excitation of the ${\chi }_{c2}$ charmonium state. Since the partial decay width for $B\to KX(3915)$ is at least an order-of-magnitude larger than that for $B\to K{\chi }_{c2}$, its assignment as the ${\chi }_{c2}^{\prime }$ is dubious.

   ↳ hep-exhep-phnucl-exEPJ Web Conf.(2019)·5 citations
10. 10*

    Heavy flavour measurements with the ALICE experiment at the LHC

    Robert Vertesi (for the ALICE Collaboration)🇭🇺

    Heavy quarks (charm and beauty) are produced early in the nucleus-nucleus collisions, and heavy flavor survives throughout the later stages. Measurements of heavy-flavor quarks thus provide us with means to understand the properties of the Quark-Gluon Plasma, a hot and dense state of matter created in heavy-ion collisions. Production of heavy-flavor in small collision systems, on the other hand, can be used to test Quantum-chromodynamics models. After a successful completion of the Run-I data taking period, the increased luminosity from the LHC and an upgraded ALICE detector system in the Run-II data taking period allows for an unprecedented precision in the study of heavy quarks. In this article we give an overview of selected recent results on heavy-flavor measurements with ALICE experiment at the LHC.

    ↳ nucl-exhep-phnucl-thUniverse(2019)·1 citation

* 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.