Fri·Jun 7, 2019Friday·June 7, 2019

1. 01*

   Integrands of loop amplitudes within loop-tree duality

   Robert Runkel🇩🇪 · Zoltán Szőr🇩🇪 · Juan Pablo Vesga🇩🇪 · Stefan Weinzierl🇩🇪

   Using loop-tree duality, we relate a renormalised $n$-point $l$-loop amplitude in a quantum field theory to a phase-space integral of a regularised $l$-fold forward limit of a UV-subtracted $(n+2l)$-point tree-amplitude-like object. We show that up to three loops the latter object is easily computable from recurrence relations. This defines an integrand of the loop amplitude with a global definition of the loop momenta. Field and mass renormalisation are performed in the on-shell scheme.

   hep-phhep-thPRD(2020)·54 citations
2. 02*

   Strongly Interacting Neutrino Portal Dark Matter

   J.M. Lamprea🇲🇽 · E. Peinado🇲🇽 · S. Smolenski🇺🇸 · J. Wudka🇺🇸

   We present a realistic, simple and natural model of strongly-interacting dark matter based on the neutrino-portal paradigm. The strong interactions at small velocities are generated by the exchange of dark photons, and produce the observed core-like DM distribution in galactic centers; this effect could be spoiled by the formation of DM bound states (also due to dark-photon effects), which we avoid by requiring the DM candidates to be light, with masses below O(10 GeV). The mixing of the dark photon with the Z and ordinary photon is strongly suppressed by introducing a softly-broken discrete symmetry similar to charge conjugation, which also ensures that the dark photon life-time is short enough to avoid restrictions derived form big-bang nucleosynthesis and large-scale structure formation. Other constraints are accommodated without the need of fine tuning, in particular nucleon scattering occurs only at one loop, so direct detection cross sections are naturally suppressed. Neutrino masses are generated through the inverse see saw.

   hep-phPRD(2021)·25 citations
3. 03*

   Magnetic field effects on neutrino oscillations

   Andrea Erdas🇺🇸 · Zachary Metzler🇺🇸

   Using the exact propagators in a constant magnetic field, the neutrino self-energy has been calculated to all orders in the field strength $B$ within the minimal extension of the Weinberg-Salam model with massive Dirac neutrinos. A neutrino dispersion relation, effective potential and effective mass have been obtained that depend on $B$. The consequences of this effective potential on neutrino oscillations have been explored, and resonance conditions have been obtained for magnetic fields $0<eB\le 4m_e^2$, where $e$ is the elementary charge and $m_e$ is the electron mass. The oscillation length has also been obtained, showing that ${\nu }_e$-${\nu }_{\mu }$ resonant oscillations in magnetic field are likely to occur in the proximity of most stars generating high magnetic fields.

   hep-phInt.J.Mod.Phys.A(2019)·0 citations
4. 04*

   Model independent analysis of New Physics effects on $B_c\to (D_s,D_s^{\ast }){\mu }^{+}{\mu }^{-}$ decay observables

   Rupak Dutta🇮🇳

   Motivated by the anomalies present in $b\to s{l}^{+}{l}^{-}$ neutral current decays, we study the corresponding $B_c\to (D_s,D_s^{\ast }){\mu }^{+}{\mu }^{-}$ decays within the standard model and beyond. We use a model independent effective theory formalism in the presence of vector and axial vector new physics operators and study the implications of the latest global fit to the $b\to s{l}^{+}{l}^{-}$ data on various observables for the $B_c\to (D_s,D_s^{\ast }){\mu }^{+}{\mu }^{-}$ decays. We give predictions on several observables such as the differential branching ratio, ratio of branching ratios, forward backward asymmetry, and the longitudinal polarization fraction of the $D_s^{\ast }$ meson within standard model and within various new physics scenarios. These results can be tested at the Large Hadron Collider and, in principle, can provide complimentary information regarding new physics in $b\to s{l}^{+}{l}^{-}$ neutral current decays.

   hep-phPRD(2019)·24 citations
5. 05*

   Production of $P_c$ states from ${\Lambda }_b$ decay

   Qi Wu🇨🇳 · Dian-Yong Chen🇨🇳

   In the present work, we investigate $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ production from ${\Lambda }_b$ decay in a molecular scenario by using an effective Lagrangian approach. We predict the ratio of the branching fraction of ${\Lambda }_b\to P_{c}K$, which is weakly dependent on our model parameter. We also find the ratios of the productions of the branching fractions of ${\Lambda }_b\to P_{c}K$ and $P_c\to J/\psi p$ can be well interpreted in the molecular scenario. Moreover, the estimated branching fractions of ${\Lambda }_b\to P_{c}K$ are of order $10^{-6}$, which could be tested by further measurements in LHCb Collaboration.

   hep-phhep-exPRD(2019)·64 citations
6. 06*

   Phenomenological studies on the $B_{d,s}^0\to J/\psi f_0(500)[f_0(980)]$ decays

   Xin Liu🇨🇳 · Zhi-Tian Zou🇨🇳 · Ying Li🇨🇳 · Zhen-Jun Xiao🇨🇳

   Encouraged by the global agreement between theoretical predictions and experimental measurements for $B\to J/\psi V$ decays, we extend that perturbative QCD formalism to $B_{d,s}^0\to J/\psi f_0(500)[f_0(980)]$ decays at the presently known next-to-leading order in the quark-antiquark description of $f_0(500)$ and $f_0(980)$. With the angle ${\varphi }_f\approx 25^{\circ }$ of the $f_0(500)-f_0(980)$ mixing in the quark-flavor basis, we find that the branching ratios of the $B_d^0\to J/\psi f_0(500)(\to {\pi }^{+}{\pi }^{-})$ and $B_{d,s}^0\to J/\psi f_0(980)(\to {\pi }^{+}{\pi }^{-})$ modes generally agree with the current data or the upper limits within uncertainties, except for the seemingly challenging $B_s^0\to J/\psi f_0(500)(\to {\pi }^{+}{\pi }^{-})$ one. Then, we further explore the relevant observables of the $B_{d,s}^0\to J/\psi f_0(500)[f_0(980)]$ decays, which could provide further constraints on the mixing angle ${\varphi }_f$ and/or SU(3) flavor symmetry breaking effects. As a byproduct, we predict $\mathrm{BR}(B_d^0\to J/\psi f_0(980)(\to K^{+}{K}^{-}))=5.8_{-2.9}^{+3.1}\times 10^{-7}$ and $\mathrm{BR}(B_s^0\to J/\psi f_0(980)(\to K^{+}{K}^{-}))=4.6_{-2.3}^{+2.6}\times 10^{-5}$. All theoretical predictions await the future examinations with high precision.

   hep-phhep-exhep-latPRD(2019)·19 citations
7. 07*

   A QCD analysis of LHCb D-meson data in p+Pb collisions

   Kari J. Eskola🇫🇮 · Ilkka Helenius🇫🇮 · Petja Paakkinen🇫🇮 · Hannu Paukkunen🇫🇮

   We scrutinize the recent LHCb data for D${}^0$-meson production in p+Pb collisions within a next-to-leading order QCD framework. Our calculations are performed in the SACOT-$m_{\mathrm{T}}$ variant of the general-mass variable-flavour-number scheme (GM-VFNS), which has previously been shown to provide a realistic description of the LHC p+p data. Using the EPPS16 and nCTEQ15 nuclear parton distribution functions (PDFs) we show that a very good agreement is obtained also in the p+Pb case both for cross sections and nuclear modification ratios in the wide rapidity range covered by the LHCb data. Encouraged by the good correspondence, we quantify the impact of these data on the nuclear PDFs by the Hessian reweighting technique. We find compelling direct evidence of gluon shadowing at small momentum fractions $x$, with no signs of parton dynamics beyond the collinear factorization. We also compare our theoretical framework to a fixed-order calculation supplemented with a parton shower. While the two frameworks differ in the absolute cross sections, these differences largely cancel in the nuclear modification ratios. Thus, the constraints for nuclear PDFs appear solid.

   hep-phJHEP(2020)·68 citations
8. 08*

   Limits on the Charged Higgs Parameters in the Two Higgs Doublet Model using CMS $\sqrt{s}=13$ TeV Results

   Prasenjit Sanyal🇮🇳

   Latest CMS results on the upper limits on ${\sigma }_{H^{\pm }}$BR($H^{\pm }\to {\tau }^{\pm }\nu )$ and ${\sigma }_{H^{\pm }}$BR($H^{+}\to t\bar{b}$) for $\sqrt{s}=13$ TeV at an integrated luminosity of 35.9 fb${}^{-1}$ are used to impose constraints on the charged Higgs $H^{\pm }$ parameters within the Two Higgs Doublet Model (2HDM). The 2HDM is the simplest extension of Standard Model (SM) under the same gauge symmetry to contain charged Higgs and is relatively less constrained compared to Minimal Supersymmetric Standard Model (MSSM). The latest results lead to much more stringent constraints on charged Higgs parameter space in comparison to the earlier 8 TeV results. The CMS collaboration also studied the exotic bosonic decay $H^{\pm }\to W^{\pm }A$ and $A\to {\mu }^{+}{\mu }^{-}$ for the first time and put upper limits on the BR($t\to H^{+}b$) for light charged Higgs. These constraints lead to exclusion of parameter space which are not excluded by the $\tau \nu$ channel. For comparison the exclusion regions from flavour physics constraints are also discussed.

   hep-phEPJC(2019)·43 citations
9. 09*

   Study of Monte Carlo event generators for proton-proton collisions at LHC energies in the forward region

   Alexandru Catalin Ene🇷🇴 · Alexandru Jipa🇷🇴 · Lavinia-Elena Giubega🇷🇴

   In this paper we present a comparative study between PYTHIA, EPOS, QGSJET, and SIBYLL generators. The global event observables considered are the charged energy flow, charged-particle distributions, charged-hadron production ratios and $V^0$ ratios. The study is performed in the LHCb and TOTEM fiducial phase-spaces on minimum bias simulated data samples for \emph{pp} collisions at $\sqrt{s}=7$ TeV using reference measurements from the aforementioned experiments. In the majority of cases, the measurements are within a band defined by the most extreme predictions. The observed differences between the predictions and the measurements seem to be, in most part, caused by extrapolation from the central pseudorapidity region ($|\eta |\le$ 2.5), in which the generators were mainly tuned.

   hep-phCPC(2019)·6 citations
10. 10*

    Relativistic bubble collisions -- a closer look

    Ryusuke Jinno🇩🇪 · Thomas Konstandin🇩🇪 · Masahiro Takimoto🇮🇱

    We study scalar bubble collisions in first-order phase transitions focusing on the relativistic limit. We propose 'trapping equation' which describes the wall behavior after collision, and test it with numerical simulations in several setups. We also examine the energy dynamics after collision and discuss its implications to gravitational wave production.

    hep-phastro-ph.COJCAP(2019)·60 citations
11. 11*

    Resummation for the Field-theoretical Derivation of the Negative Magnetoresistance

    Kenji Fukushima🇯🇵 · Yoshimasa Hidaka🇯🇵

    We show detailed derivation of the electric conductivity of quark matter at finite temperature and density under a magnetic field. We especially focus on the longitudinal electric conductivity along the magnetic direction and establish the field-theoretical description of the negative magnetoresistance as observed in chiral materials. With increasing magnetic field our microscopic calculation leads to changing behavior from approximately quadratic to asymptotically linear dependence of the electric conductivity, while the magnetic dependence is quadratic in the conventional relaxation time approximation. The presented formulation founds a firm basis for the physical interpretation of the negative magnetoresistance as manifestation of the chiral anomaly, as well as it offers general methodology applicable for various transport coefficients.

    hep-phcond-mat.str-elnucl-thJHEP(2020)·25 citations
12. 12*

    FCC-ee: Your Questions Answered

    Alain Blondel🇨🇭 · Patrick Janot🇨🇭 · Niloufar Alipour Tehrani🇨🇭 · Patrizia Azzi🇮🇹 · Paolo Azzurri🇮🇹 · Nicola Bacchetta🇮🇹 · Michael Benedikt🇨🇭 · Freya Blekman🇧🇪 · Manuela Boscolo🇮🇹 · Mogens Dam🇩🇰 · Stefania De Curtis🇮🇹 · David d'Enterria🇨🇭 and 20 other authors

    This document answers in simple terms many FAQs about FCC-ee, including comparisons with other colliders. It complements the FCC-ee CDR and the FCC Physics CDR by addressing many questions from non-experts and clarifying issues raised during the European Strategy symposium in Granada, with a view to informing discussions in the period between now and the final endorsement by the CERN Council in 2020 of the European Strategy Group recommendations. This document will be regularly updated as more questions appear or new information becomes available.

    hep-phhep-exphysics.acc-ph42 citations
13. 13*

    Leading order corrections to the Bethe-Heitler process in the $\gamma p\to l^{+}{l}^{-}p$ reaction

    Matthias Heller🇩🇪 · Oleksandr Tomalak🇩🇪 · Marc Vanderhaeghen🇩🇪 · Shihao Wu🇨🇦

    The ratio of di-lepton production cross sections on a proton, using the $\gamma p\to l^{+}{l}^{-}p$ process, above and below di-muon production threshold allows to extract the effective lepton-proton interaction, which is required to be identical for electrons and muons if lepton universality is exact. To test for a scenario of broken universality at the percent level, of the size which could explain the different proton charge radii extracted from electron scattering and from muonic hydrogen spectroscopy, we evaluate all one-loop QED corrections to this process, including the full lepton mass dependencies. We furthermore show that two-photon exchange processes with both photons attached to the proton line vanish after averaging over di-lepton angles, and estimate the relatively small radiation off the proton. We compare the full one-loop calculation with a soft-photon approximation of the same order, and present estimates for a planned experiment.

    hep-phnucl-exnucl-thPRD(2019)·16 citations
14. 14*

    The CKM unitarity problem: A trace of new physics at the TeV scale?

    Benedetta Belfatto🇮🇹 · Revaz Beradze🇬🇪 · Zurab Berezhiani🇮🇹

    After the recent high precision determinations of $V_{us}$ and $V_{ud}$, the first row of the CKM matrix shows more than $4\sigma$ deviation from unitarity. Two possible scenarios beyond the Standard Model can be investigated in order to fill the gap. If a 4th quark $b^{\prime }$ participates in the mixing, with $|V_{u{b}^{\prime }}|\sim 0.04$, then its mass should be no more than 6 TeV or so. A different solution can come from the introduction of the gauge horizontal family symmetry acting between the lepton families and spontaneously broken at the scale of about 6 TeV. Since the gauge bosons of this symmetry contribute to muon decay in positive interference with Standard Model, the Fermi constant is slightly smaller than the muon decay constant so that unitarity is recovered. Also the neutron lifetime problem, that is about $4\sigma$ discrepancy between the neutron lifetimes measured in beam and trap experiments, is discussed in the light of the these determinations of the CKM matrix elements.

    hep-phhep-latnucl-thEPJC(2020)·170 citations
15. 15*

    Simplified Template Cross Sections -- Stage 1.1 and 1.2

    Nicolas Berger🇫🇷 · Claudia Bertella🇨🇭 · Matteo Bonanomi🇩🇪 · Nihal Brahimi🇫🇷 · Thomas P. Calvet🇺🇸 · Milene Calvetti🇮🇹 · Valerio Dao🇨🇭 · Marco Delmastro🇫🇷 · Michael Duehrssen-Debling🇨🇭 · Paolo Francavilla🇮🇹 · Yacine Haddad🇺🇸 · Sarah Heim🇩🇪 and 16 other authors

    Simplified Template Cross Sections (STXS) have been adopted by the LHC experiments as a common framework for Higgs measurements. Their purpose is to reduce the theoretical uncertainties that are directly folded into the measurements as much as possible, while at the same time allowing for the combination of the measurements between different decay channels as well as between experiments. We report the complete, revised definition of the STXS kinematic bins (stage 1.1 and stage 1.2), which have been used for the measurements by the ATLAS and CMS experiments using the full LHC Run 2 datasets. The main focus is on the four dominant Higgs production processes, namely gluon-fusion, vector-boson fusion, production in association with a vector boson and in association with a $t\bar{t}$ pair. We also comment briefly on the treatment of other production modes.

    hep-phhep-exSciPost Phys.Comm.Rep.(2026)·205 citations
16. 16*

    Reheating in two-sector cosmology

    Peter Adshead🇺🇸 · Pranjal Ralegankar🇺🇸 · Jessie Shelton🇺🇸

    We analyze reheating scenarios where a hidden sector is populated during reheating along with the sector containing the Standard Model. We numerically solve the Boltzmann equations describing perturbative reheating of the two sectors, including the full dependence on quantum statistics, and study how quantum statistical effects during reheating as well as the non-equilibrium inflaton-mediated energy transfer between the two sectors affects the temperature evolution of the two radiation baths. We obtain new power laws describing the temperature evolution of fermions and bosons when quantum statistics are important during reheating. We show that inflaton-mediated scattering is generically most important at radiation temperatures $T\sim M_{\varphi }/4$, and build on this observation to obtain analytic estimates for the temperature asymmetry produced by asymmetric reheating. We find that for reheating temperatures $T_{\text{rh}}\ll M_{\varphi }/4$, classical perturbative reheating provides an excellent approximation to the final temperature asymmetry, while for $T_{\text{rh}}\gg M_{\varphi }/4$, inflaton-mediated scattering dominates the population of the colder sector and thus the final temperature asymmetry. We additionally present new techniques to calculate energy transfer rates between two relativistic species at different temperatures.

    hep-phastro-ph.COhep-thJHEP(2019)·35 citations
17. 17*

    Planck Scale Origin of Non-zero ${\theta }_{13}$ and Super-WIMP Dark Matter

    Debasish Borah🇮🇳 · Biswajit Karmakar🇮🇳 · Dibyendu Nanda🇮🇳

    We study a discrete flavour symmetric scenario for neutrino mass and dark matter under the circumstances where such global discrete symmetries can be explicitly broken at Planck scale, possibly by gravitational effects. Such explicit breaking of discrete symmetries mimic as Planck suppressed operators in the model which can have non-trivial consequences for neutrino and dark matter sectors. In particular, we study a flavour symmetric model which, at renormalisable level, gives rise to tri-bimaximal type neutrino mixing with vanishing reactor mixing angle ${\theta }_{13}=0$, a stable inert scalar doublet behaving like a weakly interacting massive particle (WIMP) and a stable singlet inert fermion which does not interact with any other particles. The introduction of Planck suppressed operators which explicitly break the discrete symmetries, can give rise to the generation of non-zero ${\theta }_{13}$ in agreement with neutrino data and also open up decay channels of inert scalar doublet into singlet neutral inert fermion leading to the realisation of the super-WIMP dark matter scenario. We show that the correct neutrino phenomenology can be obtained in this model while discussing three distinct realisation of the super-WIMP dark matter scenario.

    hep-phastro-ph.COPRD(2019)·9 citations
18. 18*

    Nonminimal Lorentz Violation in Linearized Gravity

    Matthew Mewes🇺🇸

    This contribution to the CPT'19 meeting provides a brief overview of recent theoretical studies of nonminimal Lorentz violation in linearized gravity. Signatures in gravitational waves from coalescing compact binaries are discussed.

    ↳ gr-qchep-ph3 citations
19. 19*

    Equilibrium thermodynamic susceptibilities for a dense degenerate Dirac field

    Ashish Shukla🇨🇦

    Parity preserving relativistic fluids in four spacetime dimensions admit seven independent thermodynamic susceptibilities at the second order in the hydrodynamic derivative expansion. We compute all parity-even second order thermodynamic susceptibilities for a free massive Dirac field at zero temperature and a nonzero chemical potential, based on the Kubo formulas reported in P. Kovtun and A. Shukla, Kubo formulas for thermodynamic transport coefficients, J. High Energy Phys. 10 (2018) 007. We also compute the second order constitutive relations for the energy-momentum tensor and the conserved current in the absence of external gauge fields.

    ↳ hep-thhep-phnucl-thPRD(2019)·13 citations
20. 20*

    Finite size effects on cumulants of the critical mode

    Moussa Agah Nouhou (SUBATECH, Nantes)🇫🇷 · Marcus Bluhm (Wroclaw U. & SUBATECH, Nantes)🇵🇱 · Anna Borer🇫🇷 · Marlene Nahrgang🇫🇷 · Taklit Sami🇫🇷 · Nathan Touroux (SUBATECH, Nantes)🇫🇷

    In this work we study the temperature dependence of the equilibrium variance of critical fluctuations near the QCD critical point. In particular, we take the finite size of the fireball created in heavy-ion collisions into account and systematically obtain corrections to the leading-order result. We find that not only is the variance globally reduced in a finite size system, but for certain combinations of parameters a two-peak structure can develop for temperatures near the critical point.

    ↳ nucl-thhep-phPoS(2019)·8 citations
21. 21*

    Higher order derivative operators as quantum corrections

    L. H. C. Borges🇧🇷 · F. A. Barone🇧🇷 · C. A. M. de Melo🇧🇷 · F. E. Barone🇧🇷

    In this paper we propose a non-minimal, and ghost free, coupling between the gauge field and the fermionic one from which we obtain, perturbatively, terms with higher order derivatives as quantum corrections to the photon effective action in the low energy regime. We calculate the one-loop effective action of the photon field and show that, in addition to the Euler-Heisenberg terms, the well known Lee-Wick term, $\sim F_{\mu \nu }{\partial }_{\alpha }{\partial }^{\alpha }{F}^{\mu \nu }$, arises in low energy regime as a quantum correction from the model. We also obtain the electron self energy in leading order.

    ↳ hep-thhep-phquant-phNPB(2019)·28 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.