Mon·Oct 11, 2021Monday·October 11, 2021

1. 01*

   Lepton flavor violation in the Littlest Higgs Model with T parity realizing an inverse seesaw

   Iván Pacheco🇲🇽 · Pablo Roig🇲🇽

   We study lepton flavor violation (LFV) within the Littlest Higgs Model with T parity (LHT) realizing an inverse seesaw (ISS) mechanism of type I. With respect to the traditional LHT, there appear new $\mathcal{O}$(\textcolor{black}{10} TeV) Majorana neutrinos, driving LFV. For $\tau \to \ell {\ell }^{\prime }\bar{\ell }"$ (including wrong-sign, $\ell =e,\mu$) decays and $\mu \to e$ conversion in Ti, we get typical rates only one order of magnitude below present bounds ($\ell \to {\ell }^{\prime }\gamma$ can reach the current upper limit) and for $Z\to \bar{\tau }\ell$, $\mu \to ee\bar{e}$ and conversion in Au, results are within two orders of magnitude from present limits. Correlations among modes are drastically different to the traditional LHT and other models, which would ease the confrontation of this scenario to eventual measurements of LFV processes involving charged leptons.

   hep-phJHEP(2022)·17 citations
2. 02*

   One-loop electroweak Sudakov logarithms: a revisitation and automation

   Davide Pagani🇮🇹 · Marco Zaro🇮🇹

   In this work we revisit the algorithm of Denner and Pozzorini for the calculation of one-loop electroweak Sudakov logarithms and we automate it in the MadGraph5_aMC@NLO framework. We adapt the formulas for modern calculations, keeping light-quarks and photons strictly massless and dealing with infrared divergences via dimensional regularisation. We improve the approximation by taking into account additional logarithms that are angular dependent. We prove that an imaginary term has been previously omitted and we show that it cannot be in general neglected for $2\to n$ processes with $n>2$. We extend the algorithm to NLO EW corrections to squared matrix-elements that involve also QCD corrections on top of subleading LO terms. Furthermore, we discuss the usage of this algorithm for approximating physical observables and cross sections. We propose a new approach in which the QED component is consistently removed and we show how it can be superior to the commonly used approaches. The relevance of all the novelties introduced in this work is corroborated by numerical results obtained for several processes in a completely automated way. We thoroughly compare exact NLO EW corrections and their Sudakov approximations both at the amplitude level and for physical observables in high-energy hadronic collisions.

   hep-phhep-exJHEP(2022)·40 citations
3. 03*

   Tritium beta decay with modified neutrino dispersion relations: KATRIN in the dark sea

   Guo-yuan Huang🇩🇪 · Werner Rodejohann🇩🇪

   We explore beta decays in a dark background field, which could be formed by dark matter, dark energy or a fifth force potential. In such scenarios, the neutrino's dispersion relation will be modified by its collective interaction with the dark field, which can have interesting consequences in experiments using tritium beta decays to determine the absolute neutrino mass. Among the most general interaction forms, the (pseudo)scalar and (axial-)vector ones are found to have interesting effects on the spectrum of beta decays. In particular, the vector and axial-vector potentials can induce distinct signatures by shifting the overall electron energy scale, possibly beyond the usually defined endpoint. The scalar and pseudoscalar potentials are able to mimic a neutrino mass beyond the cosmological bounds. We have placed stringent constraints on the dark potentials based on the available experimental data of KATRIN. The sensitivity of future KATRIN runs is also discussed.

   hep-phhep-exNPB(2023)·8 citations
4. 04*

   Flavor violating muon decay into an electron and a light gauge boson

   Alejandro Ibarra🇩🇪 · Marcela Marín🇲🇽 · Pablo Roig🇲🇽

   We analyze the flavor violating muon decay $\mu \to e\chi$, where $\chi$ is a massive gauge boson, with emphasis in the regime where $\chi$ is ultralight. We first study this process from an effective field theory standpoint in terms of form factors. We then present two explicit models where $\mu \to e\chi$ is generated at tree level and at the one-loop level. We also comment on the prospects of observing the process $\mu \to e\chi$ in view of the current limits on $\mu \to 3e$ from the SINDRUM collaboration.

   hep-phPLB(2022)·27 citations
5. 05*

   A pitfall in applying non-anticommuting ${\gamma }_5$ in $q\overline{q}\to ZH$ amplitudes

   Taushif Ahmed🇮🇹

   In computing the two-loop QCD corrections to a class of Feynman diagrams for the process $q\overline{q}\to ZH$ in Higgs effective field theory, we discover a striking phenomenon. We find the need for an additional local composite operator in the renormalised Lagrangian while employing a non-anticommuting ${\gamma }_5$ in dimensional regularisation. The computation using anticommuting ${\gamma }_5$, however, does not require any such amendment.

   hep-phhep-thSciPost Phys.Proc.(2022)·0 citations
6. 06*

   SO(10) Grand Unification with Minimal Dark Matter and Color Octet Scalars

   Gi-Chol Cho🇯🇵 · Kana Hayami🇯🇵 · Nobuchika Okada🇺🇸

   The minimal dark matter (MDM) scenario is a very simple framework of physics beyond the Standard Model (SM) to supplement the SM with a DM candidate. In this paper, we consider an ultraviolet completion of the scenario to an SO(10) grand unified theory, which is a well-motivated framework in light of the neutrino oscillation data. Considering various phenomenological constraints, such as the successful SM gauge coupling unification, the proton stability, and the direct/indirect DM detection constraints as well as the absolute electroweak vacuum stability, we have first singled out the minimal particle content of the MDM scenario at low energies. In addition to the SM particle content, our MDM scenario includes an SU(2)${}_L$ quintet scalar DM with a 9.4 TeV mass and three degenerate color-octet scalars with mass of 2 TeV. We then have found a way to embed the minimal particle content into SO(10) representations, in which a remnant $Z_2$ symmetry after the SO(10) symmetry breaking ensures the stability of the DM particle. The production cross section of the color-octet scalars at the Large Hadron Collider is found to be a few orders of magnitude below the current experimental bound.

   hep-phastro-ph.COhep-exPRD(2022)·6 citations
7. 07*

   Yukawa Alignment Revisited in the Higgs Basis

   Jae Sik Lee🇰🇷 · Jubin Park🇰🇷

   We implement a comprehensive and detailed study of the alignment of Yukawa couplings in the so-called Higgs basis taking the framework of general two Higgs doublet models (2HDMs). We clarify the model input parameters and derive the Yukawa couplings considering the two types of CP-violating sources: one from the Higgs potential and the other from the three complex alignment parameters ${\zeta }_{f=u,d,e}$. We consider the theoretical constraints from the perturbative unitarity and for the Higgs potential to be bounded from below as well as the experimental ones from electroweak precision observables. Also considered are the constraints on the alignment parameters from flavor-changing $\tau$ decays, $Z\to b\bar{b}$, ${ϵ}_K$, and the radiative $b\to s\gamma$ decay. By introducing the basis-independent Yukawa delay factor ${\Delta }_{H_1\bar{f}f}\equiv |{\zeta }_f|(1-g_{{}_{H_{1}VV}}^2{)}^{1/2}$, we scrutinize the alignment of the Yukawa couplings of the lightest Higgs boson to the SM fermions.

   hep-phPRD(2022)·10 citations
8. 08*

   Scalar Triplet Flavor Leptogenesis with Dark Matter

   Arghyajit Datta🇮🇳 · Rishav Roshan🇮🇳 · Arunansu Sil🇮🇳

   We investigate a simple variant of type-II seesaw, responsible for neutrino mass generation, where the particle spectrum is extended with one singlet right-handed neutrino and an inert Higgs doublet, both odd under an additional $Z_2$ symmetry. While the role of the dark matter is played by the lightest neutral component of the inert Higgs doublet, its interaction with the Standard Model lepton doublets and the right-handed neutrino turns out to be crucial in generating the correct baryon abundance of the Universe through flavored leptogenesis from the decay of the $SU(2{)}_L$ scalar triplet, involved in type-II framework.

   hep-phPRD(2022)·15 citations
9. 09*

   Analysis of trilinear Higgs self coupling in Two Higgs Doublet model at lepton collider

   Ijaz Ahmed🇵🇰 · Muhammad Danish Aslam🇵🇰 · Taimoor Khurshid🇵🇰 · Jamil Muhammad🇰🇷 · Shamona Fawad Qazi🇵🇰

   In this study, computational analysis of neutral Higgs bosons $h$, $H$ and $A$ is carried out within the parameter space of Two Higgs Doublet Model (2HDM) type-I in exact alignment limit of $\sin (\beta -\alpha )=1$ at compact linear collider. Assuming Compact Linear Collider (CLIC) scenario where the electron-positron beams will be collided at $\sqrt{s}$ = 1.5 TeV. Two different values of predicted integrated luminosities are used in our calculations, 1000 $f{b}^{-1}$ and 2500 $f{b}^{-1}$. Three signal processes $e^{+}{e}^{-}\to Zhh\to jjb\bar{b}b\bar{b}$, $e^{+}{e}^{-}\to ZHH\to jjb\bar{b}b\bar{b}$ and $e^{+}{e}^{-}\to Zhh\to jjb\bar{b}b\bar{b}$ are selected for analysis. The polarized colliding beams are used to enhance the signal production cross-section. Low $\tan \beta$ and equal Higgs masses regime is chosen in favor of Hadronic decay of $Z$ boson and $H\to b\bar{b}$. Different signal scenarios are selected and event generation is performed for each process separately. The $W$ and $Z$ boson, as well as top quark backgrounds are analyzed. Signal significance is computed at each Higgs mass hypothesis for three signal processes. After a comprehensive study, we did not find sizeable amount of signal events on top of the background but still, signal significance is found to be larger than 1, without taking into account the detector effects and systematics. The maximum calculated value of signal significance is observed to lie in the range of 150 $\le$ $m_H$ $\le$ 250 GeV for $Zhh$ while for $ZHH$ the range is 175 $\le$ $m_H$ $\le$ 200 GeV at 1000 $f{b}^{-1}$ and 175 $\le$ $m_H$ $\le$ 225 GeV region at 2500 $f{b}^{-1}$. Similarly, for $ZAA$ process, the significance is highest at $m_A$ = 175 GeV for both 1000 and 2500 $f{b}^{-1}$.

   hep-ph0 citations
10. 10*

    Probing triple higgs self coupling and effect of beam polarization in lepton colliders

    Ijaz Ahmed🇵🇰 · Ujala Nawaz🇩🇰 · Taimoor Khurshid🇵🇰 · Shamona Fawad Qazi🇵🇰

    One of the main objectives of almost all future (lepton) colliders is to measure the self-coupling of triple Higgs in the Standard Model. By elongating the Standard Model's scalar sector, using incipient Higgs doublet along with a quadratic (Higgs) potential should reveal many incipient features of the model and the possibility of the emergence of additional Higgs self-couplings. The self-coupling of the Higgs boson helps in reconstructing the scalar potential. The main objective of this paper is to extract Higgs self-coupling by numerically analyzing several scattering processes governed by two Higgs doublet models (2HDM). These scattering processes include various possible combinations of final states in the triple Higgs sector. The determination of production cross-section of scattering processes is carried out using two different scenarios, with and without polarization of incoming beam and is extended to a center of mass energy up to $\sqrt{s}$ = 3 $TeV$. The computation is carried out in Type-1 2HDM. Here we consider the case of exact alignment limit ($s_{\beta \alpha }$ = 1) and masses of extra Higgs state are equal that is $m_H=m_{H^0}=m_{A^0}=m_{H^{\pm }}$. This choice is made to minimize the oblique parameters. The decays of the final state of each process are investigated to estimate the number of events at integrated luminosity of $1a{b}^{-1}$ and $3a{b}^{-1}$.

    hep-phAdv.High Energy Phys.(2022)·2 citations
11. 11*

    On UV-completion of Palatini-Higgs inflation

    Yusuke Mikura🇯🇵 · Yuichiro Tada🇯🇵

    We investigate the UV-completion of the Higgs inflation in the metric and the Palatini formalisms. It is known that the cutoff scales for the perturbative unitarity of these inflation models become much smaller than the Planck scale to be consistent with observations. Expecting that the low cutoff scale originates in the curvature of a field-space spanned by the Higgs fields, we consider embedding the curved field-space into a higher dimensional flat space and apply this procedure to the metric-Higgs and the Palatini-Higgs scenarios. The new field introduced in this way successfully flattens the field-space and UV-completes the Higgs inflation in the metric formalism. However, in the Palatini formalism, the new field cannot uplift the cutoff up to the Planck scale. We also discuss the unavoidable low cutoff in the Palatini formalism in the context of the local conformal symmetry.

    hep-phastro-ph.COgr-qchep-thJCAP(2022)·36 citations
12. 12*

    Study of the jet transport coefficient at the Large Hadron Collider energies using Color String Percolation Model

    Dushmanta Sahu🇮🇳 · Aditya Nath Mishra🇭🇺 · Raghunath Sahoo🇮🇳

    In order to have a better understanding of the matter formed in ultra-relativistic collisions, we estimate the jet transport coefficient, $\hat{q}$, within the Color Sting Percolation Model (CSPM) for various multiplicity classes in proton-proton collisions and centrality classes in nucleus-nucleus collisions at the Large Hadron Collider energies. We study $\hat{q}$ as a function of final state charged-particle multiplicity and initial percolation temperature. Finally, we compare our obtained results with those calculated from the JET collaboration.

    hep-phhep-exnucl-exnucl-thPoS(2021)·1 citation
13. 13*

    Extension of Glauber-like model for Proton-Proton collisions using anisotropic and inhomogeneous density profile

    Suman Deb🇮🇳 · Golam Sarwar🇮🇳 · Dhananjaya Thakur🇮🇳 · Pavish S.🇩🇪 · Raghunath Sahoo🇮🇳 · Jan-e Alam🇮🇳

    Results from proton-proton ($pp$) collisions have routinely been used as a baseline to analyze and understand the production of QCD matter expected to be produced in nuclear collisions. But recent studies of small systems formed in $pp$ collisions at the LHC energies hint at the possibility of producing medium with collective behavior. Therefore, results from $pp$ collisions required more careful investigation to understand whether QCD matter is produced in high multiplicity $pp$ collisions. With this motivation, the Glauber model traditionally used to study the heavy-ion collision dynamics at high energy is applied here to understand the dynamics of $pp$ collisions. We have used anisotropic and inhomogeneous quark/gluon-based proton density profile, a realistic picture obtained from deep inelastic scattering results and this model explains the charged particle multiplicity distribution of $pp$ collisions at LHC energies very well. Collision geometric properties like impact parameter and mean number of binary collisions ($⟨N_{coll}⟩$), mean number of participants ($⟨N_{part}⟩$) at different multiplicities are determined for $pp$ collisions. We further used these collision geometric properties to estimate average charged-particle pseudorapidity density ($⟨d{N}_{ch}/d\eta ⟩$) and found it to be comparable with the experimental results. Knowing $⟨N_{coll}⟩$, we have obtained nuclear modification-like factor ($R_{pp}$) in $pp$ collisions which has not been done before to the best of our knowledge.

    hep-phhep-exnucl-exnucl-thPoS(2021)·1 citation
14. 14*

    Analysis of OPAL Bose-Einstein Correlation at $Z^0$-pole by the second conventional formula

    Takuya Mizoguchi🇯🇵 · Seiji Matsumoto🇯🇵 · Minoru Biyajima🇯🇵

    We can obtain a second conventional formula ($\mathrm{C}{\mathrm{F}}_{\mathrm{II}}$) with two components by extending the conventional formula $\mathrm{C}{\mathrm{F}}_{\mathrm{I}}$ with one component for Bose-Einstein Correlation (BEC). We used $\mathrm{C}{\mathrm{F}}_{\mathrm{II}}$ to analyze the BEC at $Z^0$-pole as part of the OPAL collaboration. $R_1(\mathrm{G})=0.91\pm 0.03$ fm (${\lambda }_1=0.61\pm 0.03$) and $R_2(\mathrm{G})=2.57\pm 0.44$ fm (${\lambda }_1=0.35\pm 0.09$) are the estimated interaction region, where ${\lambda }_1$ and ${\lambda }_2$ are the degrees of coherence, and G is the Gaussian distribution, respectively. Long range correlation (LRC) is also studied.

    hep-phhep-exnucl-thInt.J.Mod.Phys.A(2022)·2 citations
15. 15*

    Quarkonium production in pNRQCD: the $P$-wave case

    Antonio Vairo🇩🇪

    We review our recent understanding of quarkonium production at $e^{+}{e}^{-}$ and hadronic colliders from the point of view of potential non-relativistic QCD, and apply it to $P$-wave charmonium and bottomonium inclusive production.

    hep-phhep-exnucl-thPoS(2021)·1 citation
16. 16*

    Predictions on global properties in O+O collisions at the Large Hadron Collider using a multi-phase transport model

    Debadatta Behera🇮🇳 · Neelkamal Mallick🇮🇳 · Sushanta Tripathy🇮🇹 · Suraj Prasad🇮🇳 · Aditya Nath Mishra🇭🇺 · Raghunath Sahoo🇮🇳

    Oxygen (${}^{16}$O) ions are planned to be injected at the Large Hadron Collider (LHC) in its next runs, and a day of physics run is anticipated for O+O collisions at $\sqrt{s_{\mathrm{NN}}}$ = 7 TeV. As the system size of O+O collisions has the final state multiplicity overlap with those produced in pp, p+Pb and Pb+Pb collisions, the study of global properties in O+O collisions may provide a deeper insight into the heavy-ion-like behavior observed in small collision systems and its similarities/differences with a larger system like Pb+Pb collisions. In the present work, we report the predictions for global properties in O+O collisions at $\sqrt{s_{\mathrm{NN}}}$ = 7 TeV using a multi-phase transport model (AMPT). We report the mid-rapidity charged-particle multiplicity, transverse mass, Bjorken energy density, pseudo-rapidity distributions, squared speed of sound, transverse momentum ($p_{\mathrm{T}}$) spectra, the kinetic freeze-out parameters, and $p_{\mathrm{T}}$-differential particle ratio as a function of collision centrality. Further, we have studied the transverse momentum-dependent elliptic flow of charged particles. The results are shown for Woods-Saxon and harmonic oscillator nuclear density profiles. In addition, we have compared the results with an $\alpha$-clustered structure incorporated inside the oxygen nucleus. Average charged-particle multiplicity and the Bjorken energy density show a significant increase in most central collisions for the harmonic oscillator density profile, while other global properties show less dependence on the density profiles considered in this work. The results from the $\alpha$-clustered structure incorporated inside the oxygen nucleus show similar initial energy density and final charged-particle multiplicity as observed for the harmonic oscillator density profile.

    hep-phhep-exnucl-exnucl-thEPJA(2022)·46 citations
17. 17*

    Implementation of machine learning techniques to predict impact parameter and transverse spherocity in heavy-ion collisions at the LHC

    Aditya Nath Mishra🇭🇺 · Neelkamal Mallick🇮🇳 · Sushanta Tripathy🇮🇹 · Suman Deb🇮🇳 · Raghunath Sahoo🇮🇳

    Machine learning techniques have been quite popular recently in the high-energy physics community and have led to numerous developments in this field. In heavy-ion collisions, one of the crucial observables, the impact parameter, plays an important role in the final-state particle production. This being extremely small (i.e. of the order of a few fermi), it is almost impossible to measure impact parameter in experiments. In this work, we implement the ML-based regression technique via Gradient Boosting Decision Trees (GBDT) to obtain a prediction of impact parameter in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV using A Multi-Phase Transport (AMPT) model. After its successful implementation in small collision systems, transverse spherocity, an event shape observable, holds an opportunity to reveal more about the particle production in heavy-ion collisions as well. In the absence of any experimental exploration in this direction at the LHC yet, we suggest an ML-based regression method to estimate centrality-wise transverse spherocity distributions in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV by training the model with minimum bias collision data. Throughout this work, we have used a few final state observables as the input to the ML-model, which could be easily made available from collision data. Our method seems to work quite well as we see a good agreement between the simulated true values and the predicted values from the ML-model.

    hep-phhep-exnucl-exnucl-thPoS(2021)·0 citations
18. 18*

    Transverse spherocity dependence of azimuthal anisotropy in heavy-ion collisions at the LHC using a multi-phase transport model

    Neelkamal Mallick🇮🇳 · Raghunath Sahoo🇮🇳 · Sushanta Tripathy🇮🇹 · Antonio Ortiz🇲🇽

    One of the event shape observables, the transverse spherocity ($S_0$), has been studied successfully in small collision systems such as proton-proton collisions at the LHC as a tool to separate jetty and isotropic events. It has a unique capability to distinguish events based on their geometrical shapes. In this work, we report the first implementation of transverse spherocity in heavy-ion collisions using a multi-phase transport model (AMPT). We have performed an extensive study of azimuthal anisotropy of charged particles produced in heavy-ion collisions as a function of transverse spherocity ($S_0$). We have followed the two-particle correlation (2PC) method to estimate the elliptic flow ($v_2$) in different centrality classes in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV for high-$S_0$, $S_0$-integrated and low-$S_0$ events. We found that transverse spherocity successfully differentiates heavy-ion collisions event topology based on their geometrical shapes, i.e., high and low values of spherocity. The high-$S_0$ events have nearly zero elliptic flow, while the low-$S_0$ events contribute significantly to the elliptic flow of spherocity-integrated events.

    hep-phhep-exnucl-exnucl-thPoS(2021)·1 citation
19. 19*

    Medium modification type phenomena observed in high-multiplicity p+p collisions at LHC energies

    K. Dey🇮🇳 · A. N. Mishra🇭🇺 · S. K. Tripathy🇭🇺

    Nuclear modification factor predicts whether a medium is formed in a collision system or not. One may verify, if scaling of momentum (transverse) distribution from heavy-ion systems with incoherent superposition of number of binary collision, is making up the magnitude of elementary like systems. It was observed in a wide range of experimental data that in lower momentum (transverse) region, initial state effects (viz. cold-nuclear matter effect or radial flow) enhances it. While in higher momentum (transverse) region, final state effects (viz. jet quenching or re-scattering effects) suppresses it. In this article we made an attempt to predict and explain if this heavy-ion like effect can be seen in elementary collisions at favorable experimental conditions. We have employed PYTHIA8 model in this regard, and used effects which give collective-like behaviour within the model constraint. Results from this model qualitatively explains the behaviour observed in heavy-ion systems.

    hep-ph0 citations
20. 20*

    New Results For the Five Point Function

    Yang Liu🇨🇳 · Bennie F. L. Ward🇺🇸

    We present the new results of the computed general five-point functionby the magic spinor product method in loop integrals proposed by one (BFLW) of us. The result from the magic spinor product method agrees with that from LoopTools overall. Such encouraging agreements indicate that the magic spinor product method is a reliable approach with good efficiency and numerical stability.

    hep-phhep-th0 citations
21. 21*

    A Brief Look at the Chirality-Flow Formalism for Standard Model Amplitudes

    Joakim Alnefjord🇸🇪 · Andrew Lifson🇸🇪 · Christian Reuschle🇸🇪 · Malin Sjodahl🇸🇪

    Inspired by the flow description of su(N) colour calculations, we recently showed how to simplify the spinor-helicity formalism (at the algebra level two copies of complexified su(2)) by treating each Weyl spinor as part of a flow line with definite chirality and momentum. This formalism, dubbed the chirality-flow formalism, eliminates all non-trivial algebra from tree-level spinor-helicity calculations, thus allowing the shortest possible route from Feynman diagrams to complex numbers (spinor inner products). In this presentation, we briefly introduce the main features of this method and show some examples.

    hep-phhep-thPoS(2021)·3 citations
22. 22*

    SU(3) symmetry and its breaking effects in semileptonic heavy baryon decays

    Xiao-Gang He🇹🇼 · Fei Huang🇨🇳 · Wei Wang🇨🇳 · Zhi-Peng Xing🇨🇳

    We employ the flavor SU(3) symmetry to analyze semileptonic decays of anti-triplet charmed baryons (${\Lambda }_c^{+},{\Xi }_c^{+,0}$) and find that the experimental data on $\mathcal{B}({\Lambda }_c\to \Lambda {\ell }^{+}{\nu }_{\ell })$ implies $\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{e}^{+}{\nu }_e)=(4.10\pm 0.46)\%$ and $\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{\mu }^{+}{\nu }_{\mu })=(3.98\pm 0.57)\%$. When this prediction is confronted with recent experimental results from Belle collaboration $\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{e}^{+}{\nu }_e)=1.31(04\pm 07\pm 38)\%$ and $\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{\mu }^{+}{\nu }_{\mu })=1.27(06\pm 10\pm 37)\%$, it is found that the SU(3) symmetry is severely broken. We then consider the generic SU(3) breaking effects in these decays and find that the data can be accommodated in different scenarios but the breaking effects are inevitably large. In some interesting scenarios, we also explore the testable implications in these scenarios which can be tested with more data become available. Similar analyses are carried out for semileptonic anti-triplet beauty baryon to octet baryons and anti-triplet charmed baryons. The validity of SU(3) for these decays can also be examined when data become available.

    hep-phPLB(2021)·38 citations
23. 23*

    Exploring nearly degenerate higgsinos using mono-$Z/W$ signal

    Linda M. Carpenter🇺🇸 · Humberto Gilmer🇺🇸 · Junichiro Kawamura🇰🇷

    We propose a new search strategy for higgsinos. Assuming associated production of higgsino-like pairs with a $W$ or $Z$ boson, we search in the missing energy plus hadronically-tagged vector boson channel. We place sensitivity limits for (HL-)LHC searches assuming $\mathcal{O}(1-3.5\mathrm{GeV})$ mass differences between the lightest neutral and charged states. We point out that using the $E_T^{\mathrm{miss}}$ distribution significantly increases the sensitivity of this search. We find the higgsinos up to 110 (210) GeV can be excluded with $139(300){\mathrm{fb}}^{-1}$ data. The full data of the HL-LHC will exclude (discover) the higgsinos up to 520 (280) GeV.

    hep-phhep-exPLB(2022)·9 citations
24. 24*

    Next-to-leading-order QCD corrections and parton-shower effects for weakino+squark production at the LHC

    Julien Baglio🇨🇭 · Gabriele Coniglio🇩🇪 · Barbara Jager🇩🇪 · Michael Spira🇨🇭

    We present a calculation of the next-to-leading order QCD corrections to weakino+squark production processes at hadron colliders and their implementation in the framework of the POWHEG-BOX, a tool for the matching of fixed-order perturbative calculations with parton-shower programs. Particular care is taken in the subtraction of on-shell resonances in the real-emission corrections that have to be assigned to production processes of a different type. In order to illustrate the capabilities of our code, representative results are shown for selected SUSY parameter points in the pMSSM11. The perturbative stability of the calculation is assessed for the $pp\to {\tilde{\chi }}_1^0{\tilde{d}}_L$ process. For the squark+chargino production process $pp\to {\tilde{\chi }}_1^{-}{\tilde{u}}_L$ distributions of the chargino's decay products are provided with the help of the decay feature of PYTHIA 8.

    hep-phJHEP(2021)·6 citations
25. 25*

    Gravitational waves generation in turbulent hypermagnetic fields before the electroweak phase transition

    Maxim Dvornikov (IZMIRAN)🇷🇺

    We study the production of relic gravitational waves (GWs) in turbulent hypermagnetic fields (HMFs) in the symmetric phase of the early universe before the electroweak phase transition (EWPT). The noise of HMFs is modeled by the analog of the magnetic hydrodynamics turbulence. The evolution of HMFs is driven by the analogs of the chiral magnetic effect and the Adler anomalies in the presence of the nonzero asymmetries of leptons and Higgs bosons. We track the evolution of the energy density of GWs from 10 TeV down to EWPT and analyze its dependence on the parameters of the system. We also discuss the possibility to observe the predicted GW background by the current GW detectors.

    hep-phastro-ph.COgr-qcJCAP(2022)·3 citations
26. 26*

    Bubble Correlation in First-Order Phase Transitions

    V. De Luca🇨🇭 · G. Franciolini🇨🇭 · A. Riotto🇨🇭

    Making use of both the stochastic approach to the tunneling phenomenon and the threshold statistics, we offer a simple argument to show that critical bubbles may be correlated in first-order phase transitions and biased compared to the underlying scalar field spatial distribution. This happens though only if the typical energy scale of the phase transition is sufficiently high. We briefly discuss possible implications of this result, e.g. the formation of primordial black holes through bubble collisions.

    hep-phastro-ph.COgr-qchep-thPRD(2021)·18 citations
27. 27*

    Revealing New Physics in $B_s^0\to D_s^{\mp }{K}^{\pm }$ Decays

    Robert Fleischer🇳🇱 · Eleftheria Malami🇳🇱

    The $B_s^0\to D_s^{\mp }{K}^{\pm }$ system offers a determination of the Unitarity Triangle angle $\gamma$. Intrigued by an LHCb analysis showing a surprisingly large result in tension with information on the Unitarity Triangle and other $\gamma$ measurements, we make a transparent study of the measured observables, confirming the LHCb picture. The corresponding $\gamma$ puzzle at the $3\sigma$ level would require CP-violating contributions of New Physics, which should also manifest themselves in the corresponding decay branching ratios. Indeed, we find that the rates of the individual $B_s^0\to D_s^{\mp }{K}^{\pm }$ channels show puzzling patterns, in accordance with similar decays, with tensions up to $4.8\sigma$, thereby making the situation much more exciting. We present a formalism to include New-Physics effects in a model-independent way and apply it to the data to constrain the corresponding parameters. Interestingly, new contributions of moderate size could accommodate the data. Utilising this formalism in the future high-precision $B$ physics era may allow us to finally establish new sources of CP violation.

    hep-phhep-exEPJC(2023)·31 citations
28. 28*

    Primordial black holes from bubble collisions during a first-order phase transition

    Tae Hyun Jung🇺🇸 · Takemichi Okui🇺🇸

    We study the possibility of production of primordial black holes (PBHs) from bubble collisions during a first-order phase transition. While typical colliding bubbles are small and irrelevant for PBH production, we find that those that can produce PBHs must have a macroscopically thick fluid shell and have been born much before the typical nucleation time. Particularly large uncertainties arise from an exponential sensitivity of the nucleation rate on the required duration of bubble growth which depends on the details of the collisions and the evolution of the spacetime metric toward the end of the phase transition. We introduce a few parameters to be obtained from future numerical simulation to represent those unknowns, and estimate the PBH abundance in an Abelian Higgs benchmark model and show that it can be significant. We predict an approximately monochromatic PBH mass spectrum, and find regions in the parameter space where the PBHs can constitute entire dark matter or even over-close the universe. Our result thus shows that models with a first-order phase transition can be constrained by over-abundant PBHs or null results of other PBH searches.

    hep-phPRD(2024)·99 citations
29. 29*

    Temperature effects on the $Z_2$ symmetry breaking in the scotogenic model

    Alexandre Alvarez🇩🇪 · Ricardo Cepedello🇩🇪 · Martin Hirsch🇪🇸 · Werner Porod🇩🇪

    It is well-known that the scotogenic model for neutrino mass generation can explain correctly the relic abundance of cold dark matter. There have been claims in the literature that an important part of the parameter space of the simplest scotogentic model can be constrained by the requirement that no $Z_2$-breaking must occur in the early universe. Here we show that this requirement does not give any constraints on the underlying parameter space at least in those parts, where we can trust perturbation theory. To demonstrate this, we have taken into account the proper decoupling of heavy degrees of freedom in both, the thermal potential and in the RGE evolution.

    hep-phPRD(2022)·3 citations
30. 30*

    ALP Dark Matter in a Primordial Black Hole Dominated Universe

    Nicolás Bernal🇨🇴 · Yuber F. Perez-Gonzalez🇬🇧 · Yong Xu🇩🇪 · Óscar Zapata🇨🇴

    We investigate the phenomenological consequences of axion-like particle (ALP) dark matter with an early matter domination triggered by primordial black holes (PBHs). We focus on light BHs with masses smaller than $\sim 10^9$g which fully evaporate before Big Bang nucleosynthesis. We numerically solve the coupled Boltzmann equations, carefully taking the greybody factors and BH angular momentum into account. We find that the entropy injection from PBH evaporation dilutes the ALP relic abundance originally produced via the vacuum misalignment mechanism, opening the parameter space with larger scales $f_a$ or, equivalently, smaller ALP-photon couplings $g_{a\gamma }$, within the reach of future detectors as ABRACADABRA, KLASH, ADMX, and DM-Radio. Moreover, the ALP minicluster masses can be several orders of magnitude larger if the early Universe features an PBH dominated epoch. For the relativistic ALPs produced directly from Hawking radiation, we find that their contribution to the dark radiation is within the sensitivity of next generation CMB experiments. For the sake of completeness, we also revisit the particular case of the QCD axion.

    hep-phastro-ph.COPRD(2021)·64 citations
31. 31*

    Search for the decay $B^0\to K^{\ast 0}{\tau }^{+}{\tau }^{-}$ at the Belle experiment

    Belle Collaboration: T. V. Dong🇨🇳 · T. Luo🇨🇳 · I. Adachi🇯🇵 · H. Aihara🇯🇵 · D. M. Asner🇺🇸 · H. Atmacan🇺🇸 · V. Aulchenko🇷🇺 · T. Aushev🇷🇺 · R. Ayad🇸🇦 · V. Babu🇩🇪 · S. Bahinipati🇮🇳 · P. Behera🇮🇳 and 183 other authors

    This letter presents a search for the rare flavor-changing neutral current process $B^0\to K^{\ast 0}{\tau }^{+}{\tau }^{-}$ using data taken with the Belle detector at the KEKB asymmetric energy $e^{+}{e}^{-}$ collider. The analysis is based on the entire ${\rm Y}(4S)$ resonance data sample of 711 $\mathrm{f}{\mathrm{b}}^{-1}$, corresponding to $772\times 10^{6}B\bar{B}$ pairs. In our search we fully reconstruct the companion $B$ meson produced in the process $e^{+}{e}^{-}\to {\rm Y}(4S)\to B\bar{B}$ from its hadronic decay modes, and look for the decay $B^0\to K^{\ast 0}{\tau }^{+}{\tau }^{-}$ in the rest of the event. No evidence for a signal is found. We report an upper limit on the branching fraction $\mathcal{B}(B^0\to K^{\ast 0}{\tau }^{+}{\tau }^{-})<3.1\times 10^{-3}$ at 90\% confidence level. This is the first direct limit on $\mathcal{B}(B^0\to K^{\ast 0}{\tau }^{+}{\tau }^{-})$.

    ↳ hep-exhep-phPRD(2023)·50 citations
32. 32*

    Minimal dark energy: key to sterile neutrino and Hubble constant tensions?

    Eleonora Di Valentino🇬🇧 · Stefano Gariazzo🇮🇹 · Carlo Giunti🇮🇹 · Olga Mena🇪🇸 · Supriya Pan🇮🇳 · Weiqiang Yang🇨🇳

    Minimal dark energy models, described by the same number of free parameters of the standard cosmological model with cold dark matter plus a cosmological constant to parameterize the dark energy component, constitute very appealing scenarios which may solve long-standing, pending tensions. On the one hand, they alleviate significantly the tension between cosmological observations and the presence of one sterile neutrino motivated by the short-baseline anomalies: we obtain a $95\%$ CL cosmological bound on the mass of a fully thermalized fourth sterile neutrino ($N_{\mathrm{eff}}=4$) equal to $m_s<0.65(1.3)$~eV within the PEDE (VM) scenarios under consideration. Interestingly, these limits are in agreement with the observations at short-baseline experiments, and the PEDE scenario is favored with respect to the $\Lambda$CDM case when the full data combination is considered. On the other hand, the Hubble tension is satisfactorily solved in almost all the minimal dark energy schemes explored here. These phenomenological scenarios may therefore shed light on differences arising from near and far universe probes, and also on discrepancies between cosmological and laboratory sterile neutrino searches.

    ↳ astro-ph.COhep-phPRD(2022)·49 citations
33. 33*

    Hints of dark matter-neutrino interactions in Lyman-$\alpha$ data

    Deanna C. Hooper🇧🇪 · Matteo Lucca🇧🇪

    In this work we investigate the possibility that dark matter and (massive) neutrinos can interact via a simple, constant cross section. Building on previous numerical efforts, we constrain this model with CMB, BAO and, in particular, Lyman-$\alpha$ data. We find that the latter hint to a significant departure from $\Lambda$CDM, with a preference for an interaction strength about 3$\sigma$ away from zero. We trace the origin of this preference back to the additional tilt that the interacting scenario can imprint on the Lyman-$\alpha$ flux power spectrum, solving a well-known tension in the determination of this quantity between early-time and Lyman-$\alpha$ probes. Future work including complementary Lyman-$\alpha$ data as well as dedicated numerical simulations will be crucial in order to test these results.

    ↳ astro-ph.COhep-phPRD(2022)·64 citations
34. 34*

    Testing the impact of electromagnetic fields on the directed flow of constituent quarks in heavy-ion collisions

    Ashik Ikbal Sheikh🇺🇸 · Declan Keane🇺🇸 · Prithwish Tribedy🇺🇸

    It has been proposed that strong electromagnetic fields produced in the early stages of heavy-ion collisions can lead to splitting of the rapidity-odd directed flow of positive and negative hadrons. For light hadrons, the interpretation of such measurements is complicated by the low magnitude of directed flow as well as by ambiguities arising from transported quarks. To overcome these complications, we propose measurements using only hadrons carrying produced quarks ($\bar{u},\bar{d},s,\bar{s}$). We discuss how to identify the kinematics where such hadrons are produced via the coalescence mechanism and therefore their flow is the sum of the flow of their constituent quarks. With this sum rule verified for certain combinations of hadrons, the expected systematic violation of this rule with increasing electric charge can be measured, which could be a consequence of the electromagnetic fields produced in the collisions. Our approach can be tested with the high statistics data from Phase II of the Beam Energy Scan (BES) program at the Relativistic Heavy Ion Collider (RHIC).

    ↳ nucl-exhep-phnucl-thPRC(2022)·11 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.