Wed·Aug 5, 2020Wednesday·August 5, 2020

1. 01*

   CP-Violating Neutrino Non-Standard Interactions in Long-Baseline-Accelerator Data

   Peter B. Denton🇺🇸 · Julia Gehrlein🇺🇸 · Rebekah Pestes🇺🇸

   Neutrino oscillations in matter provide a unique probe of new physics. Leveraging the advent of neutrino appearance data from NOvA and T2K in recent years, we investigate the presence of CP-violating neutrino non-standard interactions in the oscillation data. We first show how to very simply approximate the expected NSI parameters to resolve differences between two long-baseline appearance experiments analytically. Then, by combining recent NOvA and T2K data, we find a tantalizing hint of CP-violating NSI preferring a new complex phase that is close to maximal: ${\varphi }_{e\mu }$ or ${\varphi }_{e\tau }\approx 3\pi /2$ with $|{ϵ}_{e\mu }|$ or $|{ϵ}_{e\tau }|\sim 0.2$. We then compare the results from long-baseline data to constraints from IceCube and COHERENT.

   hep-phhep-exPRL(2021)·116 citations
2. 02*

   Global Electroweak Fit and Vector-Like Leptons in Light of the Cabibbo Angle Anomaly

   Andreas Crivellin🇨🇭 · Fiona Kirk🇨🇭 · Claudio Andrea Manzari🇨🇭 · Marc Montull🇨🇭

   The "Cabibbo Angle Anomaly" (CAA) originates from the disagreement between the CKM elements $V_{ud}$ and $V_{us}$ extracted from superallowed beta and kaon decays, respectively, once compared via CKM unitarity. It points towards new physics with a significance of up to $4\sigma$, depending on the theoretical input used, and can be explained through modified $W$ couplings to leptons. In this context, vector-like leptons (VLLs) are prime candidates for a corresponding UV completion since they can affect $W\ell \nu$ couplings at tree-level, such that this modification can have the dominant phenomenological impact. In order to consistently asses the agreement with the data, a global fit is necessary which we perform for gauge-invariant dimension-6 operators and all patterns obtained for the six possible representations (under the SM gauge group) of VLLs. We find that even in the lepton flavour universal case, including the measurements of the CKM elements $V_{us}$ and $V_{ud}$ into the electroweak fit has a relevant impact, shifting the best fit point significantly. Concerning the VLLs we discuss the bounds from charged lepton flavour violating processes and observe that a single representation cannot describe experimental data significantly better than the SM hypothesis. However, allowing for several representations of VLLs at the same time, we find that the simple scenario in which $N$ couples to electrons via the Higgs and ${\Sigma }_1$ couples to muons not only explains the CAA but also improves the rest of the electroweak fit in such a way that its best fit point is preferred by more than $4\sigma$ with respect to the SM.

   hep-phhep-exhep-latJHEP(2020)·147 citations
3. 03*

   Generalized 331 models

   Pritibhajan Byakti🇮🇳 · Palash B. Pal🇮🇳

   We examine different ways in which the standard model can be embedded into the ${\mathrm{SU}(3)}_c\times {\mathrm{SU}(3)}_L\times {\mathrm{U}(1)}_X$ gauge group. We show that there exist families of models characterized by a free parameter. Only a few of these models, corresponding to specific values of the free parameter, have been studied so far.

   hep-ph3 citations
4. 04*

   Strong CP violation in spin-1/2 singly charmed baryons

   Y. Ünal🇹🇷 · Ulf-G. Meißner🇩🇪

   We report on the calculation of the CP-violating form factor $F_3$ and the corresponding electric dipole moment for charmed baryons in the spin-1/2 sector generated by the QCD $\theta$-term. We work in the framework of covariant baryon chiral perturbation theory within the extended-on-mass-shell renormalization scheme up to next-to-leading order in the chiral expansion.

   hep-phhep-exhep-latnucl-thJHEP(2021)·13 citations
5. 05*

   Fully-strange tetraquark $ss\bar{s}\bar{s}$ spectrum and possible experimental evidence

   Feng-Xiao Liu🇨🇳 · Ming-Sheng Liu🇨🇳 · Xian-Hui Zhong🇨🇳 · Qiang Zhao🇨🇳

   In this work we construct 36 tetraquark configurations for the $1S$-, $1P$-, and $2S$-wave states, and make a prediction of the mass spectrum for the tetraquark $ss\bar{s}\bar{s}$ system in the framework of a nonrelativistic potential quark model without the diquark-antidiquark approximation. The model parameters are well determined by our previous study of the strangeonium spectrum. We find that the resonances $f_0(2200)$ and $f_2(2340)$ may favor the assignments of ground states $T_{(ss\bar{s}\bar{s})0^{++}}(2218)$ and $T_{(ss\bar{s}\bar{s})2^{++}}(2378)$, respectively, and the newly observed $X(2500)$ at BESIII may be a candidate of the lowest mass $1P$-wave $0^{-+}$ state $T_{(ss\bar{s}\bar{s})0^{-+}}(2481)$. Signals for the other $0^{++}$ ground state $T_{(ss\bar{s}\bar{s})0^{++}}(2440)$ may also have been observed in the $\varphi \varphi$ invariant mass spectrum in $J/\psi \to \gamma \varphi \varphi$ at BESIII. The masses of the $J^{PC}=1^{--}$ $T_{ss\bar{s}\bar{s}}$ states are predicted to be in the range of $\sim 2.44-2.99$ GeV, which indicates that the $\varphi (2170)$ resonance may not be a good candidate of the $T_{ss\bar{s}\bar{s}}$ state. This study may provide a useful guidance for searching for the $T_{ss\bar{s}\bar{s}}$ states in experiments.

   hep-phhep-exPRD(2021)·48 citations
6. 06*

   Combining single and double parton scatterings in a parton shower

   Baptiste Cabouat🇬🇧 · Jonathan R. Gaunt🇨🇭

   Double parton scattering (DPS) processes in which there is a perturbative $1\to 2$ splitting in both protons overlap with loop corrections to single parton scattering (SPS). Any fundamental theoretical treatment of DPS needs to address this double-counting issue. In this paper, we augment our Monte-Carlo simulation of DPS, dShower, to be able to generate kinematic distributions corresponding to the combination SPS+DPS without double counting. To achieve this, we formulate a fully-differential version of the subtraction scheme introduced in Diehl et al. (JHEP 06 (2017) 083). A shower is attached to the subtraction term, and this is combined with the dShower DPS shower along with the usual SPS shower. We perform a proof-of-concept study of this new algorithm in the context of ${\mathrm{Z}}^0{\mathrm{Z}}^0$ production. Once the subtraction term is included, we verify that the results do not depend strongly on the artificial "DPS-SPS demarcation" scale $\nu$. As part of the development of the new algorithm, we improve the kinematics of the $1\to 2$ splitting in the DPS shower (and subtraction term), allowing the daughter partons to have a relative transverse momentum. Several reasonable choices for the transverse profile in the $1\to 2$ splitting are studied. We find that many kinematic distributions are not strongly affected by the choice, although we do observe some differences in the region where the transverse momenta of both bosons are small.

   hep-phJHEP(2020)·16 citations
7. 07*

   Sparticle Spectroscopy and Dark Matter in a $U(1{)}_{B-L}$ extension of MSSM

   Waqas Ahmed🇨🇳 · Shabbar Raza🇵🇰 · Qaisar Shafi🇺🇸 · Cem Salih Un🇹🇷 · Bin Zhu🇨🇳

   We consider a class of SUSY models in which the MSSM gauge group is supplemented with a gauged $U(1{)}_{B-L}$ symmetry and a global $U(1{)}_R$ symmetry. This extension introduces only electrically neutral states, and the new SUSY partners effectively double the number of states in the neutralino sector that now includes a blino (from $B-L$) and singlino from a gauge singlet superfield. If the DM density is saturated by a LSP neutralino, the model yields quite a rich phenomenology depending on the DM composition. The LSP relic density constraint provides a lower bound on the stop and gluino masses of about 3 TeV and 4 TeV respectively, which is testable in the near future collider experiments such as HL-LHC. The chargino mass lies between 0.24 TeV and about 2.0 TeV, which can be tested based on the allowed decay channels. We also find $m_{{\tilde{\tau }}_1}\gtrsim 500$ GeV, and $m_{\tilde{e}},m_{\tilde{\mu }},m_{{\tilde{\nu }}^{S,P}}\gtrsim 1$ TeV. We identify chargino-neutralino coannihilation processes in the mass region $0.24\mathrm{TeV}\lesssim m_{{\tilde{\chi }}_1^0}\approx m_{{\tilde{\chi }}_1^{\pm }}\lesssim 1.5$ TeV, and also coannihilation processes involving stau, selectron, smuon and sneutrinos for masses around 1 TeV. In addition, $A_2$ resonance solutions are found around 1 TeV, and $H_2$ and $H_3$ resonance solutions are also shown around 0.5 TeV and 1 TeV . Some of the $A_2$ resonance solutions with $\tan \beta \gtrsim 20$ may be tested by the $A/H\to {\tau }^{+}{\tau }^{-}$ LHC searches. While the relic density constraint excludes the bino-like DM, it is still possible to realize higgsino, singlino and blino-like DM for various mass scales. We show that all these solutions will be tested in future direct detection experiments such as LUX-Zeplin and Xenon-nT.

   hep-phJHEP(2021)·13 citations
8. 08*

   The Simple Spectrum of $c\bar{c}c\bar{c}$ States in the Dynamical Diquark Model

   Jesse F. Giron🇺🇸 · Richard F. Lebed🇺🇸

   We develop the spectroscopy of $c\bar{c}c\bar{c}$ and other all-heavy tetraquark states in the dynamical diquark model. In the most minimal form of the model (e.g., each diquark appears only in the color-triplet combination; the non-orbital spin couplings connect only quarks within each diquark), the spectroscopy is extremely simple. Namely, the $S$-wave multiplets contain precisely 3 degenerate states ($0^{++}$, $1^{+-}$, $2^{++}$) and the 7 $P$-wave states satisfy an equal-spacing rule when the tensor coupling is negligible. When comparing numerically to the recent LHCb results, we find the best interpretation is assigning $X(6900)$ to the $2S$ multiplet, while a lower state suggested at about $6740$ MeV fits well with the members of the $1P$ multiplet. We also predict the location of other multiplets ($1S$, $1D$, etc.) and discuss the significance of the $cc$ open-flavor threshold.

   hep-phhep-exnucl-thPRD(2020)·131 citations
9. 09*

   J/\psi-pair resonances by LHCb: a new revolution?

   Luciano Maiani🇮🇹

   A comment on the LHCb discovery of J/psi-pair resonances. To appear in Science Bulletin as a NEWS and VIEWS Paper.

   hep-phSci.Bull.(2020)·41 citations
10. 10*

    Towards all-order factorization of QED amplitudes at next-to-leading power

    E. Laenen🇳🇱 · J. Sinninghe Damsté🇳🇱 · L. Vernazza🇮🇹 · W. Waalewijn🇳🇱 · L. Zoppi🇳🇱

    We generalise the factorization of abelian gauge theory amplitudes to next-to-leading power (NLP) in a soft scale expansion, following a recent generalisation for Yukawa theory. From an all-order power counting analysis of leading and next-to-leading regions, we infer the factorized structure for both a parametrically small and zero fermion mass. This requires the introduction of new universal jet functions, for non-radiative and single-radiative QED amplitudes, which we compute at one-loop order. We show that our factorization formula reproduces the relevant regions in one- and two-loop scattering amplitudes, appropriately addressing endpoint divergences. It provides a description of virtual collinear modes and accounts for non-trivial hard-collinear interplay present beyond the one-loop level, making this a first step towards a complete all-order factorization framework for gauge-theory amplitudes at NLP.

    hep-phPRD(2021)·48 citations
11. 11*

    Neutrinos: Majorana or Dirac?

    S. Bilenky🇷🇺

    Are neutrinos with definite masses Majorana or Dirac particles? This is one of the most fundamental problem of the modern neutrino physics. The solution of this problem could be crucial for understanding of the origin of small neutrino masses. We will review here basic arguments in favor of the Majorana nature of massive neutrinos. The phenomenological theory of $0\nu \beta \beta$-decay is briefly discussed and recent experimental data and sensitivity of future experiments are presented.

    hep-ph19 citations
12. 12*

    BPS strings and the stability of the asymptotic Casimir law in adjoint flavor-symmetric YMH models

    D. R. Junior🇧🇷 · L. E. Oxman🇧🇷 · G. M. Simões🇧🇷

    We investigate an effective flavor-symmetric Yang-Mills-Higgs model with $N^2-1$ adjoint scalar fields. We find a set of BPS equations that provide vortex solutions and calculate their energies for arbitrary representations. We show that, for a given N-ality $k$, the energy of the corresponding antisymmetric representation is the lowest. This completes the proof that this model is able to reproduce a Casimir law for the string tension at asymptotic distances.

    ↳ hep-thhep-phPRD(2020)·5 citations
13. 13*

    Dynamics of Quintessence in Generalized Uncertainty Principle

    Alex Giacomini🇨🇱 · Genly Leon🇨🇱 · Andronikos Paliathanasis🇿🇦 · Supriya Pan🇮🇳

    We investigate the quintessence scalar field model modified by the Generalized Uncertainty Principle in the background of a spatially flat homogeneous and isotropic universe. By performing a dynamical system analysis we examine the nature of the critical points and their stability for two potentials, one is the exponential potential and the other is a general potential. In the case of an exponential potential, we find some new critical points for this modified quintessence scenario that describe the de Sitter universe, and these critical points do not appear in the standard quintessence model with an exponential potential. This is one of the main results of this work. Now for the general potential our analysis shows that the physical properties of the critical points remain exactly the same as for the exponential potential which means that within this modified quintessence scenario all kind of potentials have same behaviour. This kind of result is completely new in cosmology because with the change of the potential, differences are usually expected in all respect.

    ↳ gr-qchep-phEPJC(2020)·18 citations
14. 14*

    The multipolar structure of fuzzballs

    Massimo Bianchi🇮🇹 · Dario Consoli🇦🇹 · Alfredo Grillo🇮🇹 · Jose Francisco Morales🇮🇹 · Paolo Pani🇮🇹 · Guilherme Raposo🇮🇹

    We extend and refine a general method to extract the multipole moments of arbitrary stationary spacetimes and apply it to the study of a large family of regular horizonless solutions to $\mathcal{N}=2$ four-dimensional supergravity coupled to four Abelian gauge fields. These microstate geometries can carry angular momentum and have a much richer multipolar structure than the Kerr black hole. In particular they break the axial and equatorial symmetry, giving rise to a large number of nontrivial multipole moments. After studying some analytical examples, we explore the four-dimensional parameter space of this family with a statistical analysis. We find that microstate mass and spin multipole moments are typically (but not always) larger that those of a Kerr black hole with the same mass and angular momentum. Furthermore, we find numerical evidence that some invariants associated with the (dimensionless) moments of these microstates grow monotonically with the microstate size and display a global minimum at the black-hole limit, obtained when all centers collide. Our analysis is relevant in the context of measurements of the multipole moments of dark compact objects with electromagnetic and gravitational-wave probes, and for observational tests to distinguish fuzzballs from classical black holes.

    ↳ hep-thastro-ph.HEgr-qchep-phJHEP(2021)·67 citations
15. 15*

    Primordial Black Holes from No-Scale Supergravity

    Dimitri V. Nanopoulos🇺🇸 · Vassilis C. Spanos🇬🇷 · Ioanna D. Stamou🇬🇷

    We calculate the primordial black hole abundance in the context of a Wess-Zumino type no-scale supergravity model. We modify the Kähler potential, by adding an extra exponential term. Using just one parameter in the context of this model, we are able to satisfy the Planck cosmological constraints for the spectral index $n_s$, the tensor-to-scalar ratio $r$, and to produce up to $\sim 20\%$ of the dark matter of the Universe in the form of primordial black holes.

    ↳ astro-ph.COastro-ph.HEhep-phhep-thPRD(2020)·42 citations
16. 16*

    Constraining early dark energy with gravitational waves before recombination

    Zachary J. Weiner🇺🇸 · Peter Adshead🇺🇸 · John T. Giblin Jr🇺🇸

    We show that the nonperturbative decay of ultralight scalars into Abelian gauge bosons, recently proposed as a possible solution to the Hubble tension, produces a stochastic background of gravitational waves which is constrained by the cosmic microwave background. We simulate the full nonlinear dynamics of resonant dark photon production and the associated gravitational wave production, finding the signals to exceed constraints for the entire parameter space we consider. Our findings suggest that gravitational wave production from the decay of early dark energy may provide a unique probe of these models.

    ↳ astro-ph.COhep-phPRD(2021)·43 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.