Tue·Nov 17, 2020Tuesday·November 17, 2020

1. 01*

   Strong vertices of doubly heavy spin-3/2--spin-1/2 baryons with light mesons in light-cone QCD sum rules

   T. M. Aliev🇹🇷 · K. Şimşek🇺🇸

   In this paper, we analyze the doubly heavy spin-3/2--spin-1/2 baryons and light meson vertices within the method of light-cone QCD sum rules. These vertices are parametrized in terms of one (three) coupling constant(s) for the pseudoscalar (vector) mesons. The said coupling constants are calculated for all possible transitions. The results presented here can serve to be useful information in experimental as well as theoretical studies of the properties of doubly heavy baryons.

   hep-phPRD(2021)·11 citations
2. 02*

   Summary of the NuSTEC Workshop on Neutrino-Nucleus Pion Production in the Resonance Region

   L. Aliaga🇺🇸 · A. Ashkenazi🇺🇸 · C. Bronner🇯🇵 · J. Calcutt🇺🇸 · D. Cherdack🇺🇸 · K. Duffy🇺🇸 · S. Dytman🇺🇸 · N. Jachowicz🇧🇪 · M. Kabirnezhad🇬🇧 · K. Kuzmin🇷🇺 · G. A. Miller🇺🇸 · T. Le🇺🇸 and 11 other authors

   The NuSTEC workshop held at the University of Pittsburgh in October 2019 brought theorists and experimentalists together to discuss the state of modeling and measurements related to pion production in neutrino-nucleus scattering in the kinematic region where pions are produced through both resonant and non-resonant mechanisms. Modeling of this region is of critical importance to the current and future accelerator- and atmospheric-based neutrino oscillation experiments. For the benefit of the community, links to the presentations are accompanied by annotations from the speakers highlighting significant points made during the presentations and resulting discussions.

   hep-phhep-exnucl-exnucl-th15 citations
3. 03*

   Suppression of Electroweak Instanton Processes in High-energy Collisions

   Valentin V. Khoze🇬🇧 · Daniel L. Milne🇬🇧

   Electroweak instantons are a prediction of the Standard Model and have been studied in great detail in the past although they have not been observed. Earlier calculations of the instanton production cross section at colliders revealed that it was exponentially suppressed at low energies, but may grow large at energies (much) above the sphaleron mass. Such calculations faced difficulty in the breakdown of the instanton perturbation theory in the high-energy regime. In this paper we review the calculation for the electroweak instanton cross section using the optical theorem, including quantum effects arising from interactions in the initial state and show that this leads to an exponential suppression of the cross section at all energies, rendering the process unobservable.

   hep-phhep-thInt.J.Mod.Phys.A(2021)·15 citations
4. 04*

   Muon $g-2$ and semileptonic $B$ decays in Bélanger-Delaunay-Westhoff model with gauge kinetic mixing

   Sang Quang Dinh🇻🇳 · Hieu Minh Tran🇻🇳

   In the model proposed by Bélanger, Delaunay and Westhoff (BDW), a new sector consisted of vectorlike fermions and two complex scalars is charged under an extra Abelian symmetry $U(1{)}_X$. In this paper, we generalize the BDW model by introducing the kinetic mixing between the $U(1{)}_X$ and the standard model $U(1{)}_Y$ gauge fields. The new physics contributions to the muon anomalous magnetic moment and the Wilson coefficients $C_{9,10}^{{(}^{\prime })}$ are obtained analytically. We have explored the free parameter space of the model, taking into account various constraints on the muon $g-2$ using recent data from the E989 experiment at Fermilab, the lepton universality violation in terms of $R_K$ and $R_{K^{\ast }}$, and the branching ratios of the semileptonic decays, $B^{+}\to K^{+}{\mu }^{+}{\mu }^{-}$ and $B^0\to K^{\ast 0}{\mu }^{+}{\mu }^{-}$, the LEP and LHC searches for sleptons and $Z^{\prime }$ boson, as well as the perturbative requirement. The viable parameter regions of the model are identified. In the presence of the gauge kinetic mixing term, those regions are enlarged and significantly deformed in comparison to the case with vanishing kinetic mixing. In the near future, the E989 experiment with the projected sensitivity will be able to test significant parts of the currently allowed parameter regions.

   hep-phhep-thPRD(2021)·8 citations
5. 05*

   Hidden-charm pentaquark states through the current algebra: From their productions to decays

   Hua-Xing Chen🇨🇳

   There may exist seven ${\bar{D}}^{(\ast )}{\Sigma }_c^{(\ast )}$ hadronic molecular states. We construct their corresponding interpolating currents, and calculate their masses and decay constants using QCD sum rules. Based on these results, we calculate their relative production rates in ${\Lambda }_b^0$ decays through the current algebra, i.e., $\mathcal{B}({\Lambda }_b^0\to P_c{K}^{-}):\mathcal{B}({\Lambda }_b^0\to P_c^{\prime }{K}^{-})$ with $P_c$ and $P_c^{\prime }$ two different states. We also study their decay properties through the Fierz rearrangement, and further calculate these ratios in the $J/\psi p$ mass spectrum, i.e., $\mathcal{B}({\Lambda }_b^0\to P_c{K}^{-}\to J/\psi p{K}^{-}):\mathcal{B}({\Lambda }_b^0\to P_c^{\prime }{K}^{-}\to J/\psi p{K}^{-})$. Our results suggest that the ${\bar{D}}^{\ast }{\Sigma }_c^{\ast }$ molecular states of $J^P=1/2^{-}$ and $3/2^{-}$ are possible to be observed in future experiments.

   hep-phCPC(2022)·34 citations
6. 06*

   Can the newly $P_{cs}(4459)$ be a strange hidden-charm ${\Xi }_c{\bar{D}}^{\ast }$ molecular pentaquarks?

   Rui Chen🇨🇳

   Stimulated by the $P_{cs}(4459)$ reported by the LHCb Collaboration, we perform a single ${\Xi }_c{\bar{D}}^{\ast }$ channel and a coupled ${\Xi }_c{\bar{D}}^{\ast }/{\Xi }_c^{\ast }\bar{D}/{\Xi }_c^{\prime }{\bar{D}}^{\ast }/{\Xi }_c^{\ast }{\bar{D}}^{\ast }$ channel analysis by using a one-boson-exchange model. Our results indicate that the newly $P_{cs}(4459)$ cannot be a pure ${\Xi }_c{\bar{D}}^{\ast }$ molecular state, but a coupled ${\Xi }_c{\bar{D}}^{\ast }/{\Xi }_c^{\ast }\bar{D}/{\Xi }_c^{\prime }{\bar{D}}^{\ast }/{\Xi }_c^{\ast }{\bar{D}}^{\ast }$ bound state with $I(J^P)=0(3/2^{-})$, where the ${\Xi }_c{\bar{D}}^{\ast }$ and ${\Xi }_c^{\ast }\bar{D}$ components are dominant. Meanwhile, we find the interactions from the ${\Xi }_c^{\prime }{\bar{D}}^{\ast }$ system with $0(1/2^{-})$, the ${\Xi }_c^{\ast }\bar{D}$ system with $1(3/2^{-})$, and the ${\Xi }_c^{\ast }{\bar{D}}^{\ast }$ system with $1(1/2^{-})$ are strongly attractive, where one can expect possible strange hidden-charm molecular or resonant structures near the these thresholds with the assigned quantum numbers.

   hep-phPRD(2021)·84 citations
7. 07*

   Factorization of $e^{+}{e}^{-}\to HX$ cross section, differential in $z_h$, $P_T$ and thrust, in the $2$-jet limit

   M. Boglione🇮🇹 · A. Simonelli🇮🇹

   Factorizing the cross section for single hadron production in $e^{+}{e}^{-}$ annihilations is a highly non trivial task when the transverse momentum of the outgoing hadron with respect to the thrust axis is taken into account. We work in a scheme that allows to factorize the $e^{+}{e}^{-}\to HX$ cross section as a convolution of a calculable hard coefficient and a Transverse Momentum Dependent (TMD) fragmentation function. The result, differential in $z_h$, $P_T$ and thrust, will be given to all orders in perturbation theory and explicitly computed to Next to Leading Order (NLO) and Next to Leading Log (NLL) accuracy. The predictions obtained from our computation, applying the simplest and most natural ansatz to model the non-perturbative part of the TMD, are in exceptional agreement with the experimental measurements of the BELLE Collaboration. The factorization scheme we propose relates the TMD parton densities defined in 1-hadron and 2-hadron processes, restoring the possibility to perform global phenomenological studies of TMD physics including experimental data from semi-inclusive deep inelastic scattering, Drell-Yan processes, $e^{+}{e}^{-}\to H_1{H}_{2}X$ and $e^{+}{e}^{-}\to HX$ annihilations.

   hep-phJHEP(2021)·24 citations
8. 08*

   SM EFT effects in Vector-Boson Scattering at the LHC

   Athanasios Dedes🇬🇷 · Paweł Kozów🇵🇱 · Michał Szleper🇵🇱

   The assumption that the Standard Model is an Effective Field Theory (SM EFT) of a more fundamental theory at a higher, than electroweak, energy scale, implies a growth of cross-sections for electroweak Vector Boson Scattering (VBS) processes signalling the appearance of a resonance (or resonances) nearby that scale. In this article, we investigate in detail SM EFT effects from dimension-6 operators in VBS with like-sign-$W$ production in fully leptonic decay modes at the High Luminosity LHC (HL-LHC). We find that these effects are important for a handful of operators, most notably for the operator composed of three $SU(2)$ field strength tensors responsible for strong transversely polarized vector boson interactions. Current global fits on Wilson-coefficients allow for a signal immediately permissive at the HL-LHC if not accessible at the current LHC-dataset.

   hep-phPRD(2021)·33 citations
9. 09*

   Finite-Width Effects in Three-Body B Decays

   Hai-Yang Cheng🇹🇼 · Cheng-Wei Chiang🇹🇼 · Chun-Khiang Chua🇹🇼

   It is customary to apply the so-called narrow width approximation $\Gamma (B\to R{P}_3\to P_1{P}_2{P}_3)=\Gamma (B\to R{P}_3)Br(R\to P_1{P}_2)$ to extract the branching fraction of the quasi-two-body decay $B\to R{P}_3$, with $R$ and $P_3$ being an intermediate resonant state and a pseudoscalar meson, respectively. However, the above factorization is valid only in the zero width limit. We consider a correction parameter ${\eta }_R$ from finite width effects. Our main results are: (i) We present a general framework for computing ${\eta }_R$ and show that it can be expressed in terms of the normalized differential rate and determined by its value at the resonance. (ii) We introduce a form factor $F(s_{12},m_R)$ for the strong coupling involved in the $R(m_{12})\to P_1{P}_2$ decay when $m_{12}$ is away from $m_R$. We find that off-shell effects are small in vector meson productions, but prominent in the $K_2^{\ast }(1430)$, $\sigma /f_0(500)$ and $K_0^{\ast }(1430)$ resonances. (iii) We evaluate ${\eta }_R$ in the theoretical framework of QCD factorization (QCDF) and in the experimental parameterization (EXPP) for three-body decay amplitudes. In general, ${\eta }_R^{\mathrm{QCDF}}$ and ${\eta }_R^{\mathrm{EXPP}}$ are similar for vector mesons, but different for tensor and scalar resonances. A study of the differential rates enables us to understand the origin of their differences. (iv) Finite-width corrections to $Br(B^{-}\to RP{)}_{\mathrm{NWA}}$ obtained in the narrow width approximation are generally small, less than 10\%, but they are prominent in $B^{-}\to \sigma /f_0(500){\pi }^{-}$ and $B^{-}\to {\overline{K}}_0^{\ast 0}(1430){\pi }^{-}$ decays. The EXPP of the normalized differential rates should be contrasted with the theoretical predictions from QCDF calculation as the latter properly takes into account the energy dependence in weak decay amplitudes.

   hep-phhep-exPRD(2021)·36 citations
10. 10*

    Two-loop analysis of classically scale-invariant models with extended Higgs sectors

    Johannes Braathen🇩🇪 · Shinya Kanemura🇯🇵 · Makoto Shimoda🇯🇵

    We present the first explicit calculation of leading two-loop corrections to the Higgs trilinear coupling ${\lambda }_{hhh}$ in models with classical scale invariance (CSI), using the effective-potential approximation. Furthermore, we also study -- for the first time at two loops -- the relation that appears between the masses of all states in CSI theories, due to the requirement of reproducing correctly the 125-GeV Higgs-boson mass. In addition to obtaining analytic results for general CSI models, we consider two particular examples of Beyond-the-Standard-Model theories with extended Higgs sectors, namely an $N$-scalar model (endowed with a global $O(N)$ symmetry) and a CSI version of the Two-Higgs-Doublet Model, and we perform detailed numerical studies of these scenarios. While at one loop the value of the Higgs trilinear coupling is identical in all CSI models, and deviates by approximately $82\%$ from the (one-loop) SM prediction, we find that the inclusion of two-loop corrections lifts this universality and allows distinguishing different BSM scenarios with CSI. Taking into account constraints from perturbative unitarity and the relation among masses, we find for both types of scenarios we consider that at two loops ${\lambda }_{hhh}$ deviates from its SM prediction by $100\pm 10\%$ -- i.e. a quite significant further deviation with respect to the one-loop result of $\sim 82\%$.

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

    B-meson Nuclear Modification Factor and ${\mathbf{v}}_2({\mathbf{p}}_{\mathbf{T}})$ in a Strongly Coupled Plasma in $\mathbf{Pb}+\mathbf{Pb}$ Collisions at $\sqrt{{\mathbf{s}}_{\mathbf{NN}}}=2.76$ TeV and $\sqrt{{\mathbf{s}}_{\mathbf{NN}}}=5.5$ TeV

    B. A. Ngwenya🇿🇦 · W. A. Horowitz🇿🇦

    We present predictions for the suppression of B-mesons using AdS/CFT techniques assuming a strongly coupled quark-gluon plasma at $\sqrt{s_{NN}}=2.76$ TeV for central collisions and $\sqrt{s_{NN}}=5.5$ TeV for various centrality classes. We provide estimates of the systematic theoretical uncertainties due to 1) the mapping of QCD parameters to those in $\mathcal{N}=4$ SYM and 2) the exact form of the momentum dependence of the diffusion coefficient predicted by AdS/CFT. We show that coupling energy loss to flow increases $v_2$ substantially out to surprisingly large momenta, on the order of $\sim 25$ GeV/c, thus pointing to a possible resolution of the $R_{AA}$ and $v_2$ puzzle for light hadrons.

    hep-ph2 citations
12. 12*

    Study of Quasi-two-body $B_{(s)}\to \varphi (f_0(980)/f_2(1270)\to )\pi \pi$ Decays in Perturbative QCD Approach

    Zhi-Tian Zou🇨🇳 · Lei Yang🇨🇳 · Ying Li🇨🇳 · Xin Liu🇨🇳

    In 2017, LHCb collaboration reported their first observation of the rare decays $B_s\to \varphi (f_0(980)$ $/f_2(1270)\to ){\pi }^{+}{\pi }^{-}$ and the evidence of $B^0\to \varphi (f_0(980)/f_2(1270)\to ){\pi }^{+}{\pi }^{-}$. Motivated by this, we study these quasi-two-body decays in the perturbative QCD approach. The branching fractions, $CP$ asymmetries and the polarization fractions are calculated. We find that within the appropriate two-meson wave functions, the calculated branching fractions are in agreement with the measurements of LHCb. Based on the narrow-width approximation, We also calculate the branching fractions of the quasi-two-body $B_{d,s}\to \varphi (f_0(980)/f_2(1270)\to ){\pi }^0{\pi }^0$ and $B_{d,s}\to \varphi (f_2(1270)\to )K^{+}{K}^{-}$, and hope the predictions to be tested in the ongoing LHCb and Belle II experiments. Moreover, the processes $B_{d,s}\to \varphi f_2(1270)$ are also analyzed under this approximation. We note that the $CP$ asymmetries of these decays are very small, because these decays are either penguin dominant or pure penguin processes.

    hep-phhep-exEPJC(2021)·21 citations
13. 13*

    A possible interpretation for $X(6900)$ observed in four-muon final state by LHCb -- A light Higgs-like boson?

    Jian-Wen Zhu🇨🇳 · Xing-Dao Guo🇨🇳 · Ren-You Zhang🇨🇳 · Wen-Gan Ma🇨🇳 · Xue-Qian Li🇨🇳

    A peak structure of $J/\psi$ pair production around $6.9\mathrm{GeV}$ was observed and analyzed by the LHCb collaboration using the Run I and II data of LHC. How to understand this peak arouses enthusiastic discussions among both theorists and experimentalists of high energy physics, because this discovery might hint something new. Overwhelming works on this topic tend to attribute the peak as a four-quark state: tetraquark or molecule. Instead, we suggest that this peak is corresponding to a fundamental Higgs-like boson with mass about $6.9\mathrm{GeV}$ which is advocated by a BSM effective theory. We present a detailed analysis on both signal and SM background, including integrated cross sections and invariant mass distributions of the final-state $J/\psi$ pair. Our numerical results are well in coincidence with the experimental data, as postulating the resonance observed by LHCb to be a BSM $0^{++}$ scalar. Therefore, the peak at $M_{\text{di-}J/\psi }\sim 6.9\mathrm{GeV}$ might be a hint of new physics beyond the SM whose scale is not as large as mostly expected by high energy physicists. More further works are urgently needed in both experimental and theoretical aspects to validate or negate this assumption.

    hep-ph37 citations
14. 14*

    A new $B$-flavour anomaly in $B_{d,s}\to K^{\ast 0}{\bar{K}}^{\ast 0}$: anatomy and interpretation

    Marcel Algueró🇪🇸 · Andreas Crivellin🇨🇭 · Sébastien Descotes-Genon🇫🇷 · Joaquim Matias🇪🇸 · Martín Novoa-Brunet🇫🇷

    In the context of the recently measured non-leptonic decays $B_d\to K^{\ast 0}{\bar{K}}^{\ast 0}$ and $B_s\to K^{\ast 0}{\bar{K}}^{\ast 0}$ we analyse the anatomy of the $L_{VV}$ observable that compares the longitudinal components of $B_s\to VV$ and $B_d\to VV$ decays. This observable is cleaner than the longitudinal polarisation fraction as it is afflicted only at subleading order in a $1/m_b$ expansion by the theoretical uncertainties arising in the transverse components entering the polarisation fraction. Focusing on the particular case of $B_d\to K^{\ast 0}{\bar{K}}^{\ast 0}$ and $B_s\to K^{\ast 0}{\bar{K}}^{\ast 0}$, we discuss the main sources of hadronic uncertainty in the SM. We find for the SM prediction $L_{K^{\ast }{\bar{K}}^{\ast }}=19.5_{-6.8}^{+9.3}$, which implies a $2.6\sigma$ tension with respect to the most recent data, pointing to a deficit in the $b\to s$ transition of the non-leptonic decay versus the corresponding $b\to d$ transition. We discuss possible New Physics explanations for this deviation, first at the level of the Weak Effective Theory and we identify that the two Wilson coefficients ${\mathcal{C}}_4$ and ${\mathcal{C}}_{8g}$ can play a central role in explaining this anomaly. Finally, we briefly explore two different simplified New Physics models which can explain the anomaly through a contribution either in ${\mathcal{C}}_4$ (Kaluza-Klein gluon) or in ${\mathcal{C}}_{8g}$, with a significant amount of fine tuning, but possible connections to the $b\to s\ell \ell$ anomalies.

    hep-phJHEP(2021)·30 citations
15. 15*

    Probing Unified Theories with Reduced Couplings at Future Hadron Colliders

    Sven Heinemeyer🇪🇸 · Jan Kalinowski🇵🇱 · Wojciech Kotlarski🇩🇪 · Myriam Mondragón🇲🇽 · Gregory Patellis🇬🇷 · Nick Tracas🇬🇷 · George Zoupanos🇬🇷

    The search for renormalization group invariant relations among parameters to all orders in perturbation theory constitutes the basis of the reduction of couplings concept. Reduction of couplings can be achieved in certain $N=1$ supersymmetric Grand Unified Theories and few of them can become even finite at all loops. We review the basic idea, the tools that have been developed as well as the resulting theories in which successful reduction of couplings has been achieved so far. These include: (i) a reduced version of the minimal $N=1$ $SU(5)$ model, (ii) an all-loop finite $N=1$ $SU(5)$ model, (iii) a two-loop finite $N=1$ $SU(3{)}^3$ model and finally (vi) a reduced version of the Minimal Supersymmetric Standard Model. In this paper we present a number of benchmark scenarios for each model and investigate their observability at existing and future hadron colliders. The heavy supersymmetric spectra featured by each of the above models are found to be beyond the reach of the 14 TeV HL-LHC. It is also found that the reduced version of the MSSM is already ruled out by the LHC searches for heavy neutral MSSM Higgs bosons. In turn the discovery potential of the 100 TeV FCC-hh is investigated and found that large parts of the predicted spectrum of these models can be tested, but the higher mass regions are beyond the reach even of the FCC-hh.

    hep-phEPJC(2021)·11 citations
16. 16*

    Can discovery of hidden charm strange pentaquark states help determine the spins of $P_c(4440)$ and $P_c(4457)$?

    Ming-Zhu Liu🇨🇳 · Ya-Wen Pan🇨🇳 · Li-Sheng Geng🇨🇳

    The pentaquark states, $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$, could be nicely arranged into a multiplet of seven molecules of ${\bar{D}}^{(\ast )}{\Sigma }_c^{(\ast )}$ dictated by heavy quark spin symmetry. However, the spins of $P_c(4440)$ and $P_c(4457)$ are not yet fully determined. In this work we employ the contact-range effective field theory to investigate the $SU(3)$-flavor counterparts of ${\bar{D}}^{(\ast )}{\Sigma }_c^{(\ast )}$, and study the possibility whether their discovery can help determine the spins of $P_c(4457)$ and $P_c(4440)$. We find the existence of a complete hidden charm strange multiplet of ${\bar{D}}^{(\ast )}{\Xi }_c^{(\prime \ast )}$ molecules irrespective of the spins of $P_c(4440)$ and $P_c(4457)$. On the other hand, we find that although molecules of ${\bar{D}}^{(\ast )}{\Xi }_c$ are also likely, depending on the realization of the underlying dynamics, their discovery can be more useful to determine the spins of $P_c(4440)$ and $P_c(4457)$ and to tell how the heavy quark and light quark interaction depends on the spin of the light quark pair.

    hep-phPRD(2021)·74 citations
17. 17*

    Transmutation of protons in a strong electromagnetic field

    Tobias N. Wistisen🇩🇪 · Christoph H. Keitel🇩🇪 · Antonino Di Piazza🇩🇪

    The process of turning a proton into a neutron, positron and electron-neutrino in a strong plane-wave electromagnetic field is studied. This process is forbidden in vacuum and is seen to feature an exponential suppression factor which is non-perturbative in the field amplitude. The suppression is alleviated when the proton experiences a field strength of about ten times the Schwinger critical field in its rest frame or larger. Around this threshold the lifetime of the proton, in its rest frame, is comparable to the conventional neutron decay lifetime. As the field strength is increased, the proton lifetime becomes increasingly short. We investigate possible scenarios where this process may be observed in the laboratory using an ultra-intense laser and a high-energy proton beam with the conclusion, however, that it would be very challenging to observe this effect in the near future.

    hep-phnucl-thNew J.Phys.(2021)·10 citations
18. 18*

    Xenon-1T excess as a possible signal of a sub-GeV hidden sector dark matter

    Amin Aboubrahim🇩🇪 · Michael Klasen🇩🇪 · Pran Nath🇺🇸

    We present a particle physics model to explain the observed enhancement in the Xenon-1T data at an electron recoil energy of 2.5 keV. The model is based on a $U(1)$ extension of the Standard Model where the dark sector consists of two essentially mass degenerate Dirac fermions in the sub-GeV region with a small mass splitting interacting with a dark photon. The dark photon is unstable and decays before the big bang nucleosynthesis, which leads to the dark matter constituted of two essentially mass degenerate Dirac fermions. The Xenon-1T excess is computed via the inelastic exothermic scattering of the heavier dark fermion from a bound electron in xenon to the lighter dark fermion producing the observed excess events in the recoil electron energy. The model can be tested with further data from Xenon-1T and in future experiments such as SuperCDMS.

    hep-phJHEP(2021)·23 citations
19. 19*

    Reflection Identities of Harmonic Sums and pole decomposition of BFKL eigenvalue

    Mohammad Joubat🇮🇱 · Alex Prygarin🇮🇱

    We analyze known results of next-to-next-to-leading(NNLO) singlet BFKL eigenvalue in $N=4$ SYM written in terms of harmonic sums. The nested harmonic sums building known NNLO BFKL eigenvalue for specific values of the conformal spin have poles at negative integers. We sort the harmonic sums according to the complexity with respect to their weight and depth and use their pole decomposition in terms of the reflection identities to find the most complicated terms of NNLO BFKL eigenvalue for an arbitrary value of the conformal spin. The obtained result is compatible with the Bethe-Salpeter approach to the BFKL evolution.

    hep-phhep-thInt.J.Mod.Phys.A(2021)·6 citations
20. 20*

    Blast from the past: Constraints on the dark sector from the BEBC WA66 beam dump experiment

    Giacomo Marocco🇬🇧 · Subir Sarkar🇬🇧

    We derive limits on millicharged dark states, as well as particles with electric or magnetic dipole moments, from the number of observed forward electron scattering events at the Big European Bubble Chamber in the 1982 CERN-WA-066 beam dump experiment. The dark states are produced by the 400 GeV proton beam primarily through the decays of mesons produced in the beam dump, and the lack of excess events places bounds extending up to GeV masses. These improve on bounds from all other experiments, in particular CHARM II.

    hep-phSciPost Phys.(2021)·79 citations
21. 21*

    A study on the isolated photon production in nuclear collisions at the CERN-LHC energies

    G. Sampaio dos Santos🇧🇷 · G. Gil da Silveira🇧🇷 · M. V. T. Machado🇧🇷

    An analysis of prompt photon production in high energy nuclear collisions at the LHC energy regime is performed within the parton saturation picture taking into account the updated phenomenological color dipole models. The results are confronted with the measurements made by the ALICE, ATLAS, and CMS experiments in terms of photon transverse momentum at different rapidity bins. As a result, we show that the prompt photon production exhibits distinct scalings in $AA$ events associated to geometrical properties of the collision and can be properly addressed in the color dipole formalism.

    hep-phhep-exJ.Phys.G(2022)·4 citations
22. 22*

    Dark Matter candidates in a Type-II radiative neutrino mass model

    Roberto A. Lineros🇨🇱 · Mathias Pierre🇪🇸

    We explore the connection between Dark Matter and neutrinos in a model inspired by radiative Type-II seessaw and scotogenic scenarios. In our model, we introduce new electroweakly charged states (scalars and a vector-like fermion) and impose a discrete ${\mathbb{Z}}_2$ symmetry. Neutrino masses are generated at the loop level and the lightest ${\mathbb{Z}}_2$-odd neutral particle is stable and it can play the role of a Dark Matter candidate. We perform a numerical analysis of the model showing that neutrino masses and flavour structure can be reproduced in addition to the correct dark matter density, with viable DM masses from 700 GeV to 30 TeV. We explore direct and indirect detection signatures and show interesting detection prospects by CTA, Darwin and KM3Net and highlight the complementarity between these observables.

    hep-phastro-ph.HEJHEP(2020)·6 citations
23. 23*

    Effective Field Theory for Heavy Vector Resonances Coupled to the Standard Model

    Mathias Heiles🇩🇪 · Matthias König🇨🇭 · Matthias Neubert🇩🇪

    We construct an effective field theory describing the decays of a heavy vector resonance $V$ into Standard Model particles. The effective theory is built using an extension of Soft-Collinear Effective Theory called SCET${}_{\mathrm{BSM}}$, which provides a rigorous framework for parameterizing decay matrix elements with manifest power counting in the ratio of the electroweak scale and the mass of the resonance, $\lambda \sim v/m_V$. Using the renormalization-group evolution of the couplings in the effective Lagrangian, large logarithms associated with this scale ratio can be resummed to all orders. We consider in detail the two-body decays of a heavy $Z^{\prime }$ boson and of a Kaluza-Klein gluon at leading and subleading order in $\lambda$. We illustrate the matching onto SCET${}_{\mathrm{BSM}}$ with a concrete example of a UV-complete new-physics model.

    hep-phJHEP(2021)·10 citations
24. 24*

    Electroweak Form Factor in Sudakov and Threshold Regimes with Effective Field Theories

    B. Assi🇩🇪 · B.A. Kniehl🇩🇪

    We compute the massive gauge and scalar corrections to form factors in both the Sudakov and threshold regimes up to and including two-loop orders. The corrections are calculated for processes involving two external fermions and scalars in the spontaneously broken SU(N)-Higgs model, examining a range of composite operators. Our results are general, so we discuss how our form factors are mappable from our model to the Standard Model and beyond. The effective theory formalism deployed in our work extends previous studies based on infrared evolution equations, which either neglect scalar contributions or are restricted to the Sudakov regime.

    hep-ph3 citations
25. 25*

    Search of spin-dependent fifth forces with precision magnetometry

    N. Crescini🇮🇹 · G. Carugno🇮🇹 · P. Falferi🇮🇹 · A. Ortolan🇮🇹 · G. Ruoso🇮🇹 · C.C. Speake🇬🇧

    Spin-dependent fifth-forces are associated with particles beyond the standard model. In particular, light pseudo-scalar bosons mediate long-range forces, allowing mass to interact with spins. The search of these interactions can be performed by periodically varying the distance between a source mass and a spin ensemble, in order to modulate the force intensity and detect it with precision magnetometry techniques. In our setup the force arises from room temperature lead masses and is detected in a paramagnetic crystal at 4.2\,K, whose magnetisation is monitored by a SQUID-based magnetometer with the sensitivity of $53aT/\sqrt{\mathrm{Hz}}$. Our measurement places the most stringent constraints on a spin-mass interaction in the ranges 1\,cm to 10\,m and 10\,km to 300\,km, improving existing limits up to more than two orders of magnitude. We show that this experimental technique may be further leveraged to explore a vast region of the fifth force's parameter space, with an interaction range longer than a few centimetres.

    ↳ hep-exhep-phphysics.ins-detPRD(2022)·26 citations
26. 26*

    Lepton Flavour Asymmetries and the Mass Spectrum of Primordial Black Holes

    Dietrich Bodeker🇩🇪 · Florian Kuhnel🇩🇪 · Isabel M. Oldengott🇪🇸 · Dominik J. Schwarz🇩🇪

    We study the influence of lepton flavour asymmetries on the formation and the mass spectrum of primordial black holes. We estimate the detectability of their mergers with LIGO/Virgo and show that the currently published gravitational wave events may actually be described by a primordial black hole spectrum from non-zero asymmetries. We suggest to use gravitational-wave astronomy as a novel tool to probe how lepton flavour asymmetric the Universe has been before the onset of neutrino oscillations.

    ↳ astro-ph.COgr-qchep-phPRD(2021)·26 citations
27. 27*

    Modular transformations of elliptic Feynman integrals

    Stefan Weinzierl🇩🇪

    We investigate the behaviour of elliptic Feynman integrals under modular transformations. This has a practical motivation: Through a suitable modular transformation we can achieve that the nome squared is a small quantity, leading to fast numerical evaluations. Contrary to the case of multiple polylogarithms, where it is sufficient to consider just variable transformations for the numerical evaluations of multiple polylogarithms, it is more natural in the elliptic case to consider a combination of a variable transformation (i.e. a modular transformation) together with a redefinition of the master integrals. Thus we combine a coordinate transformation on the base manifold with a basis transformation in the fibre. Only in the combination of the two transformations we stay within the same class of functions.

    ↳ hep-thhep-phNPB(2021)·35 citations
28. 28*

    Weak Value Amplification in High Energy Physics: A Case Study for Precision Measurement of CP Violation in B Meson Decays

    Satoshi Higashino🇯🇵 · Yuichiro Mori🇯🇵 · Yosuke Takubo🇯🇵 · Takeo Higuchi🇯🇵 · Akimasa Ishikawa🇯🇵 · Izumi Tsutsui🇯🇵

    The technique of weak value amplification, proposed by Aharonov et al. in 1988, has been applied for various fields of physics for the purpose of precision measurement, which is made possible by exploiting the freedom of `postselection' specifying actively the final state in the physical process. Here we report for the first time the feasibility of utilizing the technique of weak value amplification in high energy particle physics, especially in measuring the CP-violating parameters in B meson decays, where the effective lifetime of the decay mode is expected to be prolonged statistically due to the postselection. Our analysis shows that, when adopted in the Belle II experiment at the SuperKEKB collider, the effective lifetime may be prolonged up to 2.6 times, and that the measurement precision of the CP-violating parameters will also be improved by its effect.

    ↳ quant-phhep-exhep-phhep-thPRD(2021)·2 citations
29. 29*

    What are Elementary Particles? From Dark Energy to Quantum Field Excitations

    Wolfgang Bietenholz🇲🇽

    We describe the very nature of the elementary particles, which our (visible) Universe consists of. We point out that they are not point-like, and we depict their ways of interacting. We also address puzzles that occur even in the absence of particles, in the vacuum.

    ↳ physics.pop-phhep-phRev. Cub. Fis. 37 (2020) 146-151·2 citations
30. 30*

    Observation of a near-threshold structure in the $K^{+}$ recoil-mass spectra in $e^{+}{e}^{-}\to K^{+}(D_s^{-}{D}^{\ast 0}+D_s^{\ast -}{D}^0)$

    BESIII Collaboration: M. Ablikim🇨🇳 · M. N. Achasov🇷🇺 · P. Adlarson🇸🇪 · S. Ahmed🇩🇪 · M. Albrecht🇩🇪 · R. Aliberti🇩🇪 · A. Amoroso🇮🇹 · Q. An🇨🇳 · Anita🇮🇳 · X. H. Bai🇨🇳 · Y. Bai🇨🇳 · O. Bakina🇷🇺 and 493 other authors

    We report a study of the processes of $e^{+}{e}^{-}\to K^{+}(D_s^{-}{D}^{\ast 0}+D_s^{\ast -}{D}^0)$ based on $e^{+}{e}^{-}$ annihilation samples collected with the BESIII detector operating at BEPCII at five center-of-mass energies ranging from 4.628 to 4.698 GeV with a total integrated luminosity of 3.7 fb${}^{-1}$. An excess over the known contributions of the conventional charmed mesons is observed near the $D_s^{-}{D}^{\ast 0}$ and $D_s^{\ast -}{D}^0$ mass thresholds in the $K^{+}$ recoil-mass spectrum for events collected at $\sqrt{s}=4.681$ GeV. The structure matches a mass-dependent-width Breit-Wigner line shape, whose pole mass and width are determined as $(3982.5_{-2.6}^{+1.8}\pm 2.1)$ MeV/$c^2$ and $(12.8_{-4.4}^{+5.3}\pm 3.0)$ MeV, respectively. The first uncertainties are statistical and the second are systematic. The significance of the resonance hypothesis is estimated to be 5.3 $\sigma$ over the contributions only from the conventional charmed mesons. This is the first candidate of the charged hidden-charm tetraquark with strangeness, decaying into $D_s^{-}{D}^{\ast 0}$ and $D_s^{\ast -}{D}^0$. However, the properties of the excess need further exploration with more statistics.

    ↳ hep-exhep-phnucl-exnucl-thPRL(2021)·290 citations
31. 31*

    Selection rules for the S-Matrix bootstrap

    Anjishnu Bose🇮🇳 · Aninda Sinha🇮🇳 · Shaswat S Tiwari🇮🇳

    We examine the space of allowed S-matrices on the Adler zeros' plane using the recently resurrected (numerical) S-matrix bootstrap program for pion scattering. Two physical quantities, an averaged total scattering cross-section, and an averaged entanglement power for the boundary S-matrices, are studied. Emerging linearity in the leading Regge trajectory is correlated with a reduction in both these quantities. We identify two potentially viable regions where the S-matrices give decent agreement with low energy S- and P-wave scattering lengths and have leading Regge trajectory compatible with experiments. We also study the line of minimum averaged total cross section in the Adler zeros' plane. The Lovelace-Shapiro model, which was a precursor to modern string theory, is given by a straight line in the Adler zeros' plane and, quite remarkably, we find that this line intersects the space of allowed S-matrices near both these regions.

    ↳ hep-thhep-phSciPost Phys.(2021)·44 citations
32. 32*

    The cosmology of sub-MeV dark matter freeze-in

    Cora Dvorkin🇺🇸 · Tongyan Lin🇺🇸 · Katelin Schutz🇺🇸

    Dark matter (DM) could be a relic of freeze-in through a light mediator, where the DM is produced by extremely feeble, IR-dominated processes in the thermal Standard Model plasma. In the simplest viable models with the DM mass below the MeV scale, the DM has a small effective electric charge and is born with a nonthermal phase-space distribution. This DM candidate would cause observable departures from standard cosmological evolution. In this work, we combine data from the cosmic microwave background (CMB), Lyman-$\alpha$ forest, quasar lensing, stellar streams, and Milky Way satellite abundances to set a lower limit on freeze-in DM masses up to $\sim 20$keV, with the exact constraint depending on whether the DM thermalizes in its own sector. We perform forecasts for the CMB-S4 experiment, the Hydrogen Epoch of Reionization Array, and the Vera Rubin Observatory, finding that freeze-in DM masses up to $\sim 80$keV can be explored. These cosmological probes are highly complementary with proposed direct-detection efforts to search for this DM candidate.

    ↳ astro-ph.COhep-phPRL(2021)·78 citations
33. 33*

    Hierarchical clustering in particle physics through reinforcement learning

    Johann Brehmer🇺🇸 · Sebastian Macaluso🇺🇸 · Duccio Pappadopulo🇺🇸 · Kyle Cranmer🇺🇸

    Particle physics experiments often require the reconstruction of decay patterns through a hierarchical clustering of the observed final-state particles. We show that this task can be phrased as a Markov Decision Process and adapt reinforcement learning algorithms to solve it. In particular, we show that Monte-Carlo Tree Search guided by a neural policy can construct high-quality hierarchical clusterings and outperform established greedy and beam search baselines.

    ↳ cs.AIcs.LGhep-ph8 citations
34. 34*

    Einstein, Planck and Vera Rubin: relevant encounters between the Cosmological and the Quantum Worlds

    Paolo Salucci🇮🇹 · Giampiero Esposito🇮🇹 · Gaetano Lambiase🇮🇹 · Emmanuele Battista🇮🇹 · Micol Benetti🇮🇹 · Donato Bini🇮🇹 · Lumen Boco🇮🇹 · Gauri Sharma🇮🇹 · Valerio Bozza🇮🇹 · Luca Buoninfante🇮🇹 · Antonio Capolupo🇮🇹 · Salvatore Capozziello🇮🇹 and 29 other authors

    In Cosmology and in Fundamental Physics there is a crucial question like: where the elusive substance that we call Dark Matter is hidden in the Universe and what is it made of?, that, even after 40 years from the Vera Rubin seminal discovery does not have a proper answer. Actually, the more we have investigated, the more this issue has become strongly entangled with aspects that go beyond the established Quantum Physics, the Standard Model of Elementary particles and the General Relativity and related to processes like the Inflation, the accelerated expansion of the Universe and High Energy Phenomena around compact objects. Even Quantum Gravity and very exotic DM particle candidates may play a role in framing the Dark Matter mystery that seems to be accomplice of new unknown Physics. Observations and experiments have clearly indicated that the above phenomenon cannot be considered as already theoretically framed, as hoped for decades. The Special Topic to which this review belongs wants to penetrate this newly realized mystery from different angles, including that of a contamination of different fields of Physics apparently unrelated. We show with the works of this ST that this contamination is able to guide us into the required new Physics. This review wants to provide a good number of these "paths or contamination" beyond/among the three worlds above; in most of the cases, the results presented here open a direct link with the multi-scale dark matter phenomenon, enlightening some of its important aspects. Also in the remaining cases, possible interesting contacts emerges.

    ↳ gr-qcastro-ph.GAhep-phhep-thFront.in Phys.(2021)·66 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.