Mon·Dec 28, 2020Monday·December 28, 2020

1. 01*

   Left-Right Symmetric Model without Higgs Triplets

   K.S. Babu🇺🇸 · Anil Thapa🇺🇸

   We develop a minimal left-right symmetric model based on the gauge group $SU(3{)}_C\otimes SU(2{)}_L\otimes SU(2{)}_R\otimes U(1{)}_{B-L}$ wherein the Higgs triplets conventionally employed for symmetry breaking are replaced by Higgs doublets. Majorana masses for the right-handed neutrinos $({\nu }_R$) are induced via two-loop diagrams involving a charged scalar field ${\eta }^{+}$. This setup is shown to provide excellent fits to neutrino oscillation data via the seesaw mechanism for the entire range of the $W_R^{\pm }$ mass, from TeV to the GUT scale. When the $W_R^{\pm }$ mass is at the TeV scale, the ${\nu }_R$ masses turn out to be in the MeV range. We analyze constraints from low energy experiments, early universe cosmology and from supernova 1987a on such a scenario and show its consistency. We also study collider implications of a relatively light ${\eta }^{+}$ scalar through its decay into multi-lepton final states and derive a lower limit of 390 GeV on its mass from the LHC, which can be improved to 555 GeV in its high luminosity run.

   hep-ph16 citations
2. 02*

   Production of $X(3872)$ at High Multiplicity

   Eric Braaten🇺🇸 · Li-Ping He🇺🇸 · Kevin Ingles🇺🇸 · Jun Jiang🇨🇳

   The dependence of the production of the $X(3872)$ meson on the hadron multiplicity in $pp$ collisions has been used as evidence against $X$ being a charm-meson molecule. The argument is based in part on the incorrect assumption that the cross section for the breakup of $X$ by scattering with comovers can be approximated by a geometric cross section inversely proportional to the binding energy of $X$. The breakup cross section should instead be approximated by the probability-weighted sum of the cross sections for the scattering of comoving pions from the charm-meson constituents of $X$, which is insensitive to the binding energy. A simple modification of the comover interaction model gives excellent fits to the data from the LHCb collaboration on the multiplicity dependence of the production of $X$ and $\psi (2S)$ using parameters compatible with $X$ being a loosely bound charm-meson molecule.

   hep-phhep-exPRD(2021)·55 citations
3. 03*

   Neutrino masses and gravitational wave background

   Takehiko Asaka🇯🇵 · Hisashi Okui🇯🇵

   We consider the Standard Model with three right-handed neutrinos to generate tiny neutrino masses by the seesaw mechanism. Especially, we investigate the case when one right-handed neutrino has the suppressed Yukawa coupling constants. Such a particle has a long lifetime and can produce an additional entropy by the decay. It is then discussed the impact of the entropy production on the gravitational wave background originated in the primordial inflation. We show that the mass and the coupling constants of the long-lived right-handed neutrino can be probed by the distortion of the gravitational wave spectrum, leading to the information of the mass of the lightest active neutrino.

   hep-phastro-ph.COgr-qcPLB(2021)·6 citations
4. 04*

   Two-loop leading-color helicity amplitudes for three-photon production at the LHC

   Herschel A. Chawdhry🇬🇧 · Michal Czakon🇩🇪 · Alexander Mitov🇬🇧 · Rene Poncelet🇬🇧

   We calculate all planar contributions to the two-loop massless helicity amplitudes for the process $q\bar{q}\to \gamma \gamma \gamma$. The results are presented in fully analytic form in terms of the functional basis proposed recently by Chicherin and Sotnikov. With this publication we provide the two-loop contributions already used by us in the NNLO QCD calculation of the LHC process $pp\to \gamma \gamma \gamma$ [Chawdhry et al. (2019)]. Our results agree with a recent calculation of the same amplitude [Abreu et al. (2020)] which was performed using different techniques. We combine several modern computational techniques, notably, analytic solutions for the IBP identities, finite-field reconstruction techniques as well as the recent approach [Chen (2019)] for efficiently projecting helicity amplitudes. Our framework appears well-suited for the calculation of two-loop multileg amplitudes for which complete sets of master integrals exist.

   hep-phhep-thJHEP(2021)·71 citations
5. 05*

   Trapping Effect for QCD Axion Dark Matter

   Shota Nakagawa🇯🇵 · Fuminobu Takahashi🇯🇵 · Masaki Yamada🇯🇵

   In the early universe, the potential of a scalar field can be significantly modified, and the scalar field may be trapped for a long time in a different location than the current vacuum. The trapping effect can increase or decrease the scalar abundance. For instance, in thermal inflation, a scalar field is trapped at the top of the potential by a thermal effect and dominates the universe to drive inflation for a short period of time. On the other hand, a scalar abundance can be exponentially suppressed in the adiabatic suppression mechanism, where a scalar field moves adiabatically by a time-dependent trapping potential. In this study, we investigate such a trapping effect on the abundance of scalar fields. Specifically, we investigate how the abundance of a scalar field depends on its initial position in the case of a double well potential and identify the physical quantity that controls the abundance. Then, we study the QCD axion abundance for various values of the misalignment angle, where the axon potential receives a large temporal mass due to the Witten effect. We find that the axion abundance is suppressed due to the adiabatic suppression mechanism even when it is trapped near the maximum of the potential, if the trapping effect is sufficiently large.

   hep-phJCAP(2021)·41 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.