Mon·Feb 8, 2021Monday·February 8, 2021

1. 01*

   Hot QCD at finite isospin density: confronting SU(3) Nambu-Jona-Lasinio model with recent lattice data

   Bruno. S. Lopes🇧🇷 · Sidney S. Avancini🇧🇷 · Aritra Bandyopadhyay🇨🇳 · Dyana C. Duarte🇺🇸 · Ricardo L. S. Farias🇧🇷

   Extending our recently published $SU(2)$ results for zero temperature we now compute the QCD equation of state for finite isospin density within the three flavor Nambu-Jona-Lasinio model in the mean field approximation, motivated by the recently obtained Lattice QCD results for both zero and finite temperatures. Like our previous study, here also we have considered both the commonly used Traditional cutoff Regularization Scheme and the Medium Separation Scheme. Our results are compared with recent high-precision lattice simulations as well as previously obtained results in two-flavor Nambu-Jona-Lasinio model. The agreement between the lattice results and the predictions from three-flavor NJL model is very good for low values of ${\mu }_I$ (for both zero and finite temperatures). For larger values of ${\mu }_I$, the agreement between lattice data and the two-flavor NJL predictions is surprisingly good and better than with the three-flavor predictions.

   hep-phhep-lathep-thnucl-thPRD(2021)·31 citations
2. 02*

   On the interpretation of $\Lambda$ spin polarization measurements

   Wojciech Florkowski🇵🇱 · Radoslaw Ryblewski🇵🇱

   The physics interpretation of the recent measurements of the spin polarization of $\Lambda$ hyperons produced in relativistic heavy-ion collisions is discussed. We suggest that the polarization measured in the $\Lambda$ rest frame should be projected along the direction of the total angular momentum that is first transformed to the same frame, and only then averaged over $\Lambda$'s with different momenta in the center-of-mass frame. While this procedure does not affect the current measurements done in a broad transverse-momentum range, it may become important (represent a correction of about 10\%) for the most energetic hyperons under study (with transverse momenta reaching 4-5 GeV/c). The proposed treatment is generally more appropriate for relativistic $\Lambda$'s. Throughout the paper, we deliver explicit expressions for various boosts, rotations, and transformations of angular distributions, which may help to compare model predictions with the experimental results.

   hep-phnucl-exnucl-thPRC(2022)·18 citations
3. 03*

   A translational flavor symmetry in the mass terms of Dirac and Majorana fermions

   Zhi-zhong Xing🇨🇳

   Requiring the effective mass term for a category of fundamental Dirac or Majorana fermions of the same electric charge to be invariant under the translational transformations ${\psi }_{\alpha \mathrm{L}(\mathrm{R})}^{}\to {\psi }_{\alpha \mathrm{L}(\mathrm{R})}^{}+n_{\alpha }^{}{z}_{\psi \mathrm{L}(\mathrm{R})}^{}$ in the flavor space, where $n_{\alpha }^{}$ and $z_{\psi \mathrm{L}(\mathrm{R})}^{}$ stand respectively for the flavor-dependent complex numbers and a constant spinor field anticommuting with the fermion fields, we show that $n_{\alpha }^{}$ can be identified as the elements $U_{\alpha i}^{}$ in the $i$-th column of the unitary matrix $U$ used to diagonalize the corresponding Hermitian or symmetric fermion mass matrix $M_{\psi }^{}$, and $m_i^{}=0$ holds accordingly. We find that the reverse is also true. Now that the mass spectra of charged leptons, up- and down-type quarks are all strongly hierarchical and current experimental data allow the lightest neutrino to be massless, we argue that the zero mass limit for the first-family fermions and the translational flavor symmetry behind it should be a natural starting point for building viable fermion mass models.

   hep-phhep-thJ.Phys.G(2022)·4 citations
4. 04*

   Scalar Dark Matter in $A_4$ based texture one-zero neutrino mass model within Inverse Seesaw Mechanism

   Rishu Verma🇮🇳 · Monal Kashav🇮🇳 · Surender Verma🇮🇳 · B. C. Chauhan🇮🇳

   In this paper, we present a model based on $A_4$ discrete flavor symmetry implementing inverse and type-II seesaw mechanisms to have LHC accessible TeV scale right-handed neutrino mass and texture one-zero in the resulting Majorana neutrino mass matrix, respectively. We investigate neutrino and dark matter sectors of the model. Non-Abelian discrete $A_4$ symmetry spontaneously breaks into $Z_2$ subgroup and hence provide stable dark matter candidate. To constrain the Yukawa Lagrangian of our model, we imposed $Z_2^{\prime }$, $Z_3$ and $Z_4$ cyclic symmetries in addition to the $A_4$ flavor symmetry. In this work we used the recently updated data on cosmological parameters from PLANCK 2018. For the dark matter candidate mass around 45 GeV-55 GeV, we obtain the mediator particle mass(right-handed neutrinos) ranging from 138 GeV to 155 GeV. The Yukawa couplings is found to be in the range 0.995-1 to have observed relic abundance of dark matter. We, further, obtain inverse ($X\equiv \frac{F^{2}n}{z^2}$) and type-II ($X^{{}^{\prime }}\equiv f_1{v}_{{\Delta }_1}$) seesaw contributions to $0\nu \beta \beta$ decay amplitude $|M_{ee}|$, while model being consistent with low energy experimental constraints. In particular, we emphasize that type-II seesaw contribution to $|M_{ee}|$ is large as compared to inverse seesaw contribution for normally ordered(NO) neutrino masses.

   hep-phPTEP(2021)·13 citations
5. 05*

   The electromagnetic form factors of ${\Lambda }_c$ hyperon in the vector meson dominance model

   Junyao Wan🇨🇳 · Yongliang Yang🇨🇳 · Zhun Lu🇨🇳

   We apply a modified vector meson dominance (VMD) model to analyze the electromagnetic form factors of the ${\Lambda }_c$ hyperon in the time-like reaction $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$. In the model, we include the contributions from the vector charmed mesons and their excitations $\psi (1S)$, $\psi (2S)$, $\psi (3770)$, $\psi (4040)$, $\psi (4160)$ and $\psi (4415)$. We perform a combined fit to the available data on the Born cross section in reaction $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ and the ratio of the electromagnetic form factors $|G_E/G_M|$ to obtain the values of the model parameters. Our results show that the VMD model can simultaneously describe the data of electromagnetic form factors from the Belle and BESIII Collaborations, and the behavior of $|G_E/G_M|$ for the BESIII data can be qualitatively reproduced by the VMD model prediction at the threshold region. Moreover, we predict the single and double polarization observables in $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ reactions, which are experimentally accessible in the polarized process. We also obtain the form factors of the ${\Lambda }_c$ hyperon in the space-like region via analytic continuing the time-like form factors.

   hep-phEur.Phys.J.Plus(2021)·10 citations
6. 06*

   LIGO as a probe of Dark Sectors

   Fei Huang🇨🇳 · Veronica Sanz🇪🇸 · Jing Shu🇨🇳 · Xiao Xue🇨🇳

   We show how current LIGO data is able to probe interesting theories beyond the Standard Model, particularly Dark Sectors where a Dark Higgs triggers symmetry breaking via a first-order phase transition. We use publicly available LIGO O2 data to illustrate how these sectors, even if disconnected from the Standard Model, can be probed by Gravitational Wave detectors. We link the LIGO measurements with the model content and mass scale of the Dark Sector, finding that current O2 data is testing a broad set of scenarios where the breaking of $SU(N)$ theories with $N_f$ fermions is triggered by a Dark Higgs at scales $\Lambda \simeq 10^8-10^9$ GeV with reasonable parameters for the scalar potential.

   hep-phgr-qcPRD(2021)·17 citations
7. 07*

   Probing the structure of the $B$ meson with $B\to \ell \ell {\ell }^{\prime }\nu$

   Aoife Bharucha🇫🇷 · Bharti Kindra🇮🇳 · Namit Mahajan🇮🇳

   We consider the decay $B\to \ell \ell {\ell }^{\prime }\nu$ in QCD factorization for the case of non-zero (but small) $q^2$, taking into account leading power contributions at NLL in $\mathcal{O}({\alpha }_s)$ and next-to-leading power corrections at $\mathcal{O}({\alpha }_s^0)$. We further incorporate soft contributions obtained from light-cone sum rules, extrapolated from the Euclidean to physical region using once-subtracted dispersion relations. We restrict ourselves to the case $\ell \ne {\ell }^{\prime }$ as otherwise the same sign $\ell$ and ${\ell }^{\prime }$ cannot be distinguished. We study the sensitivity of the results to the leading moment of the $B$-meson distribution amplitude and discuss the potential to extract this quantity at LHCb and the Belle II experiment.

   hep-ph9 citations
8. 08*

   Combined NLO EW and QCD corrections to off-shell $\text{t}\overline{\text{t}}\text{W}$ production at the LHC

   Ansgar Denner🇩🇪 · Giovanni Pelliccioli🇩🇪

   The high luminosity that will be accumulated at the LHC will enable precise differential measurements of the hadronic production of a top--antitop-quark pair in association with a $\text{W}$ boson. Therefore, an accurate description of this process is needed for realistic final states. In this work we combine for the first time the NLO QCD and electroweak corrections to the full off-shell $\text{t}\overline{\text{t}}{\text{W}}^{+}$ production at the LHC in the three-charged-lepton channel, including all spin correlations, non-resonant effects, and interferences. To this end, we have computed the NLO electroweak radiative corrections to the leading QCD order as well as the NLO QCD corrections to both the QCD and the electroweak leading orders.

   hep-phEPJC(2021)·51 citations
9. 09*

   $t\bar{t}H$ production at NNLO: the flavour off-diagonal channels

   Stefano Catani🇮🇹 · Ignacio Fabre🇨🇭 · Massimiliano Grazzini🇨🇭 · Stefan Kallweit🇮🇹

   We consider QCD radiative corrections to the associated production of a heavy-quark pair ($Q\bar{Q}$) with a generic colourless system $F$ at hadron colliders. We discuss the resummation formalism for the production of the $Q\bar{Q}F$ system at small values of its total transverse momentum $q_T$. The perturbative expansion of the resummation formula leads to the explicit ingredients that can be used to apply the $q_T$ subtraction formalism to fixed-order calculations for this class of processes. We use the $q_T$ subtraction formalism to perform a fully differential perturbative computation for the production of a top-antitop quark pair and a Higgs boson. At next-to-leading order we compare our results with those obtained with established subtraction methods and we find complete agreement. We present, for the first time, the results for the flavour off-diagonal partonic channels at the next-to-next-to-leading order.

   hep-phEPJC(2021)·56 citations
10. 10*

    Perturbative corrections to power suppressed effects in $\bar{B}\to X_u\ell \nu$

    Bernat Capdevila🇮🇹 · Paolo Gambino🇮🇹 · Soumitra Nandi🇮🇳

    We compute the $O({\alpha }_s)$ corrections to the Wilson coefficients of the dimension five operators in inclusive semileptonic $B$ decays in the limit of a massless final quark. Our calculation agrees with reparameterization invariance and with previous results for the total width and places constraints on the shape functions that enter those decays.

    hep-phJHEP(2021)·14 citations
11. 11*

    On the quantum origin of a dark universe

    Saurya Das🇨🇦 · Mohit Kumar Sharma🇮🇳 · Sourav Sur🇮🇳

    It has been shown beyond reasonable doubt that the majority (about 95%) of the total energy budget of the universe is given by the dark components, namely Dark Matter and Dark Energy. What constitutes these components remains to be satisfactorily understood however, despite a number of promising candidates. An associated conundrum is that of the coincidence, i.e. the question as to why the Dark Matter and Dark Energy densities are of the same order of magnitude at the present epoch, after evolving over the entire expansion history of the universe. In an attempt to address these, we consider a quantum potential resulting from a quantum corrected Raychaudhuri/Friedmann equation in presence of a cosmic fluid, which is presumed to be a Bose-Einstein condensate (BEC) of ultralight bosons. For a suitable and physically motivated macroscopic ground state wavefunction of the BEC, we show that a unified picture of the cosmic dark sector can indeed emerge, thus resolving the issue of the coincidence. The effective Dark energy component turns out to be a cosmological constant, by virtue of a residual homogeneous term in the quantum potential. Furthermore, comparison with the observational data gives an estimate of the mass of the constituent bosons in the BEC, which is well within the bounds predicted from other considerations.

    ↳ gr-qcastro-ph.COhep-phhep-thPhys.Sci.Forum(2021)·4 citations
12. 12*

    Extracting the low-energy constant $L_0^r$ at three flavors from pion-kaon scattering

    Chaitra Kalmahalli Guruswamy🇩🇪 · Ulf-G. Meißner🇩🇪 · Chien-Yeah Seng🇩🇪

    Based on our analysis of the contributions from the connected and disconnected contraction diagrams to the pion-kaon scattering amplitude, we provide the first determination of the only free low-energy constant at $\mathcal{O}(p^4)$, known as $L_0^r$, in SU$(4|1)$ Partially-Quenched Chiral Perturbation Theory using the data from the Extended Twisted Mass Collaboration, $L_0^r(\mu =M_{\rho })=0.77(20)(25)(7)(7)(2)\cdot 10^{-3}$. The theory uncertainties originate from the unphysical scattering length, the physical low-energy constants, the higher-oder chiral corrections, the (lattice) meson masses and the pion decay constant, respectively

    ↳ hep-lathep-phnucl-thCommun.Theor.Phys.(2022)·1 citation
13. 13*

    Testing the Bethe ansatz with large N renormalons

    Marcos Marino🇨🇭 · Ramon Miravitllas🇨🇭 · Tomas Reis🇨🇭

    The ground state energy of integrable asymptotically free theories can be conjecturally computed by using the Bethe ansatz, once the theory has been coupled to an external potential through a conserved charge. This leads to a precise prediction for the perturbative expansion of the energy. We provide a non-trivial test of this prediction in the non-linear sigma model and its supersymmetric extension, by calculating analytically the associated Feynman diagrams at next-to-leading order in the $1/N$ expansion, and at all loops. By investigating the large order behaviour of the diagrams, we locate the position of the renormalons of the theory and we obtain an analytic expression for the large $N$ trans-series associated to each. As a spin-off of our calculation, we provide a direct derivation of the beta function of these theories, at next-to-leading order in the $1/N$ expansion.

    ↳ hep-thhep-phmath-phmath.MPEur.Phys.J.ST(2021)·32 citations
14. 14*

    Determining the leading-order contact term in neutrinoless double $\mathbf{\beta }$ decay

    Vincenzo Cirigliano🇺🇸 · Wouter Dekens🇺🇸 · Jordy de Vries🇳🇱 · Martin Hoferichter🇨🇭 · Emanuele Mereghetti🇺🇸

    We present a method to determine the leading-order (LO) contact term contributing to the $nn\to pp{e}^{-}{e}^{-}$ amplitude through the exchange of light Majorana neutrinos. Our approach is based on the representation of the amplitude as the momentum integral of a known kernel (proportional to the neutrino propagator) times the generalized forward Compton scattering amplitude $n(p_1)n(p_2)W^{+}(k)\to p(p_1^{\prime })p(p_2^{\prime })W^{-}(k)$, in analogy to the Cottingham formula for the electromagnetic contribution to hadron masses. We construct model-independent representations of the integrand in the low- and high-momentum regions, through chiral EFT and the operator product expansion, respectively. We then construct a model for the full amplitude by interpolating between these two regions, using appropriate nucleon factors for the weak currents and information on nucleon-nucleon ($NN$) scattering in the ${}^1{S}_0$ channel away from threshold. By matching the amplitude obtained in this way to the LO chiral EFT amplitude we obtain the relevant LO contact term and discuss various sources of uncertainty. We validate the approach by computing the analog $I=2$ $NN$ contact term and by reproducing, within uncertainties, the charge-independence-breaking contribution to the ${}^1{S}_0$ $NN$ scattering lengths. While our analysis is performed in the $\overline{\mathrm{MS}}$ scheme, we express our final result in terms of the scheme-independent renormalized amplitude ${\mathcal{A}}_{\nu }(|\mathbf{p}|,|{\mathbf{p}}^{\prime }|)$ at a set of kinematic points near threshold. We illustrate for two cutoff schemes how, using our synthetic data for ${\mathcal{A}}_{\nu }$, one can determine the contact-term contribution in any regularization scheme, in particular the ones employed in nuclear-structure calculations for isotopes of experimental interest.

    ↳ nucl-thhep-lathep-phJHEP(2021)·81 citations
15. 15*

    Diversity and inclusion activities in Belle II

    H.M. Wakeling🇨🇦 · S.A. De La Motte🇦🇺 · M. Barrett🇯🇵 · K. Kinoshita🇺🇸

    These proceedings accompany the Belle II talk in the Diversity and Inclusion parallel session delivered during ICHEP 2020. This marks the first external presentation by the Belle II Collaboration, in which we present some of our data and self-reported statistics regarding diversity and inclusion. We also present Belle II's current and planned activities to aid and improve diversity and inclusion. We find that there is still a lot to be done to improve the social working environment and population representation within our collaboration and within high energy physics.

    ↳ physics.ed-phhep-exhep-phphysics.soc-phPoS(2021)·0 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.