Thu·Jan 7, 2021Thursday·January 7, 2021

1. 01*

   Cone size dependence of jet suppression in heavy-ion collisions

   Yacine Mehtar-Tani🇺🇸 · Daniel Pablos🇳🇴 · Konrad Tywoniuk🇳🇴

   The strong suppression of high-$p_T$ jets in heavy ion collisions is a result of elastic and inelastic energy loss suffered by the jet multi-prong collection of color charges that are resolved by medium interactions. Hence, quenching effects depend on the fluctuations of the jet substructure that are probed by the cone size dependence of the spectrum. In this letter, we present the first complete, analytic calculation of the inclusive $R$-dependent jet spectrum in PbPb collisions at LHC energies, including resummation of energy loss effects from hard, vacuum-like emissions occurring in the medium and modeling of soft energy flow and recovery at the jet cone. Both the geometry of the collision and the local medium properties, such as the temperature and fluid velocity, are given by a hydrodynamic evolution of the medium, leaving only the coupling constant in the medium as a free parameter. The calculation yields a good description of the centrality and $p_T$ dependence of jet suppression for $R=0.4$ together with a mild cone size dependence, which is in agreement with recent experimental results. Gauging the theoretical uncertainties, we find that the largest sensitivity resides in the leading logarithmic approximation of the phase space of resolved splittings, which can be improved systematically, while non-perturbative modeling of the soft-gluon sector is of relatively minor importance up to large cone sizes.

   hep-phnucl-thPRL(2021)·85 citations
2. 02*

   Reviving chaotic inflation with fermion production: a supergravity model

   Michael A. Roberts🇺🇸 · Lorenzo Sorbo🇺🇸

   Processes of particle production during inflation can increase the amplitude of the scalar metric perturbations. We show that such a mechanism can naturally arise in supergravity models where an axion-like field, whose potential is generated by monodromy, drives large field inflation. In this class of models one generally expects instanton-like corrections to the superpotential. We show, by deriving the equations of motion in models of supergravity with a stabilizer, that such corrections generate an interaction between the inflaton and its superpartner. This inflaton-inflatino interaction term is rapidly oscillating, and can lead to copious production of fermions during inflation, filling the Fermi sphere up to momenta much larger than the Hubble parameter. In their turn, those fermions source inflaton fluctuations, increasing their amplitude, and effectively lowering the tensor-to-scalar ratio for the model, as discussed in [1, 2]. This allows, in particular, to bring the model where the inflaton potential is quadratic (plus negligibly small instanton corrections) to agree with all existing observations.

   hep-phastro-ph.COhep-thJCAP(2021)·7 citations
3. 03*

   Parametrization of Quark and Gluon Generalized Parton Distributions in a Dynamical Framework

   Brandon Kriesten🇺🇸 · Philip Velie🇺🇸 · Emma Yeats🇺🇸 · Fernanda Yepez Lopez🇺🇸 · Simonetta Liuti🇺🇸

   We present a parametrization of the chiral even generalized parton distributions, $H$, $E$, $\tilde{H}$, $\tilde{E}$, for the quark, antiquark and gluon, in the perturbative QCD-parton framework. Parametric analytic forms are given as a function of two equivalent sets of variables $x,\xi ,t$ (symmetric frame) and $X,\zeta ,t$ (asymmetric frame), at an initial scale, $Q_o^2$. In the $X>\zeta$ region a convenient and flexible form is obtained as the product of a Regge term $\propto X^{-\alpha +{\alpha }^{\prime }t}$, describing the low $X$ behavior, times a spectator model-based functional form depending on various mass parameters; the behavior at $X<\zeta$, is determined using the generalized parton distributions symmetry and polynomiality properties. The parameters are constrained using data on the flavor separated nucleon electromagnetic elastic form factors, the axial and pseudoscalar nucleon form factors, and the parton distribution functions from both the deep inelastic unpolarized and polarized nucleon structure functions. For the gluon distributions we use, in particular, constraints provided by recent lattice QCD moments calculations. The parametrization's kinematical range of validity is: $0.0001\le X\le 0.85$, $0.01\le \zeta \le 0.85$, $0\le -t\le 1$ GeV${}^2$, $2\le Q^2\le 100$ GeV${}^2$. With the simultaneous description of the quark, anti-quark and gluon sectors, this parametrization represents a first tool enabling a global QCD analysis of deeply virtual exclusive experiments.

   hep-phPRD(2022)·55 citations
4. 04*

   Tests of the Atomki anomaly in lepton pair decays of heavy mesons

   G. López Castro🇲🇽 · Néstor Quintero🇨🇴

   The anomalies recently reported in lepton pair transitions of ${}^8$Be${}^{\ast }$ and ${}^4$He nuclei may be attributed to the existence of a feebly interacting light vector boson $X17$. We study the effects of this hypothetical particle in the semileptonic $H^{\ast }\to H{e}^{+}{e}^{-}$ decays ($H$ a $Q\bar{q}$ meson) in the framework of the HQET+VMD model. Using current bounds and the universality assumption of the $X17$ boson to quarks, we find that decays of $D^{\ast +}$ and $D_s^{\ast +}$ mesons can be importantly enhanced relative to the dominant photon-mediated contributions. Dedicated experimental searches at current heavy meson factories may confirm the existence of this light boson or set stronger bounds of their couplings to ordinary matter.

   hep-phhep-exPRD(2021)·14 citations
5. 05*

   Primordial black holes and scotogenic dark matter

   Teruyuki Kitabayashi🇯🇵

   We study the effect of the scotogenic dark matter on the primordial black holes (PBHs) and vice versa. We show that if the PBHs evaporate in the radiation dominant era, the upper limit of the initial mass of the PBHs $M_{\mathrm{in}}$ should be constrained as $10^4\lesssim M_{\mathrm{in}}/M_{\mathrm{Pl}}\lesssim 10^{10}$ for $\mathcal{O}$(1) TeV scotogenic dark matter ($\mathcal{O}$(1) TeV is the most appropriate energy scale in the scotogenic model). On the other hand, if the PBHs evaporate in the PBH dominated era, a quite heavy scotogenic dark matter ($m_{/rmDM}/gtrsim10^9$ GeV) for $M_{/rmin}/M_{/rmPl}/sim10^{13}$ may be allowed.

   hep-phInt.J.Mod.Phys.A(2021)·29 citations
6. 06*

   Finding $B_c(3S)$ States via Their Strong Decays

   Rui Ding🇨🇳 · Bing-Dong Wan🇨🇳 · Zi-Qiang Chen🇨🇳 · Guo-Li Wang🇨🇳 · Cong-Feng Qiao🇨🇳

   The experimentally known $B_c$ states are all below open bottom-charm threshold, which experience three main decay modes, and all induced by weak interaction. In this work, we investigate the mass spectrum and strong decays of the $B_c(3S)$ states, which just above the threshold, in the Bethe-Salpeter formalism and ${}^3{P}_0$ model. The numerical estimation gives $M(B_c(3^1{S}_0))=7273\mathrm{MeV}$, $M(B_c^{\ast }(3^3{S}_1))=7304\mathrm{MeV}$, $\Gamma \left(B_c(3^1{S}_0)\to B^{\ast }D\right)=26.02_{-2.21}^{+2.33}\mathrm{MeV}$, $\Gamma \left(B_c^{\ast }(3^3{S}_1)\to BD\right)=3.39_{-0.26}^{+0.27}\mathrm{MeV}$, $\Gamma \left(B_c^{\ast }(3^3{S}_1)\to B^{\ast }D\right)=14.77_{-1.33}^{+1.40}\mathrm{MeV}$ and $\Gamma \left(B_c^{\ast }(3^3{S}_1)\to B{D}^{\ast }\right)=6.14_{-0.54}^{+0.58}\mathrm{MeV}$. Compared with previous studies in non-relativistic approximation, our results indicate that the relativistic effects are notable in $B_c(3S)$ exclusive strong decays. According to the results, we suggest to find the $B_c(3S)$ states in their hadronic decays to $B$ and $D$ mesons in experiment, like the LHCb.

   hep-phPLB(2021)·9 citations
7. 07*

   HIP and HEP

   Urs Achim Wiedemann🇨🇭

   This write-up of the ICHEP plenary "Heavy Ions - theory" focusses on some recent LHC discoveries and future opportunities in heavy ion physics (HIP) that are at the intersection with high energy physics (HEP).

   hep-phPoS(2021)·5 citations
8. 08*

   Decay of baryon inhomogeneities in an expanding universe

   Pratik K. Das🇮🇳 · Sovan Sau🇮🇳 · Abhisek Saha🇮🇳 · Soma Sanyal🇮🇳

   Baryon inhomogeneities can be generated very early in the universe. These inhomogeneities then decay by particle diffusion in an expanding universe. We study the decay of these baryon inhomogeneities in the early universe using the diffusion equation in the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric. We have studied the decay starting from the electroweak phase transition. We calculate the interaction cross section of the quarks with the neutrinos, the electrons and the muons and obtain the diffusion coefficients. The diffusion coefficients are temperature dependent. We find that the expansion of the universe causes the inhomogeneities to decay at a faster rate. We find that the baryon inhomogeneities generated at the electroweak epoch have very low amplitudes at the time of the quark hadron phase transition. So unless inhomogeneities are generated with a very high amplitude (greater than $10^5$ times the background density), they will have no effect on the quark hadron phase transition. After the quark hadron phase transition, we include the interaction of the muons with the neutrons and the protons till 100 MeV. We also find that large density inhomogeneities generated during the quark hadron transition with sizes of the order of 1 km must have amplitudes greater than $10^5$ times the background density to survive upto the nucleosynthesis epoch in an expanding universe.

   hep-phEPJC(2021)·0 citations
9. 09*

   Low scale Dirac leptogenesis and dark matter with observable $\Delta N_{\mathrm{eff}}$

   Devabrat Mahanta🇮🇳 · Debasish Borah🇮🇳

   We propose a gauged $B-L$ extension of the standard model (SM) where light neutrinos are of Dirac type by virtue of tiny Yukawa couplings with the SM Higgs. To achieve leptogenesis, we include additional heavy Majorana fermions without introducing any $B-L$ violation by two units. An additional scalar doublet with appropriate $B-L$ charge can allow heavy fermion coupling with the SM leptons so that out of equilibrium decay of the former can lead to generation of lepton asymmetry. Due to the $B-L$ gauge interactions of the decaying fermion, the criteria of successful Dirac leptogenesis can also constrain the gauge sector couplings so as to keep the corresponding washout processes under control. The same $B-L$ gauge sector parameter space can also be constrained from dark matter requirements if the latter is assumed to be a SM singlet particle with non-zero $B-L$ charge. The same $B-L$ gauge interactions also lead to additional thermalised relativistic degrees of freedom $\Delta N_{\mathrm{eff}}$ from light Dirac neutrinos which are tightly constrained by Planck 2018 data. While there exists parameter space from the criteria of successful low scale Dirac leptogenesis, dark matter and $\Delta N_{\mathrm{eff}}$ even after incorporating the latest collider bounds, all the currently allowed parameters can be probed by future measurements of $\Delta N_{\mathrm{eff}}$.

   hep-phastro-ph.COEPJC(2022)·33 citations
10. 10*

    Chiral Soliton Models and Nucleon Structure Functions

    Herbert Weigel🇿🇦 · Ishmael Takyi🇬🇭

    We outline and review the computations of polarized and unpolarized nucleon structure functions within the bosonized Nambu-Jona-Lasinio chiral soliton model. We focus on a consistent regularization prescription for the Dirac sea contribution and present numerical results from that formulation. We also reflect on previous calculations on quark distributions in chiral quark soliton models and attempt to put them into perspective.

    hep-phnucl-thSymmetry(2021)·3 citations
11. 11*

    QCD pressure: renormalization group optimized perturbation theory confronts lattice

    Jean-Loïc Kneur🇫🇷 · Marcus Benghi Pinto🇧🇷 · Tulio E. Restrepo🇧🇷

    The quark contribution to the QCD pressure, $P_q$, is evaluated up to next-to-leading order (NLO) within the renormalization group optimized perturbation theory (RGOPT) resummation approach. To evaluate the complete QCD pressure we simply add the perturbative NLO contribution from massless gluons to the resummed $P_q$. Despite of this unsophisticated approximation our results for $P=P_q+P_g$ at the central scale $M\sim 2\pi T$ show a remarkable agreement with ab initio lattice predictions for $0.25\lesssim T\lesssim 1\mathrm{GeV}$. We also show that by being imbued with RG properties, the RGOPT produces a drastic reduction of the embarrassing remnant scale dependence that plagues both standard thermal perturbative QCD and hard thermal loop perturbation theory (HTLpt) applications.

    hep-phhep-lathep-thnucl-thPRD(2021)·13 citations
12. 12*

    Relic density of dark matter in the inert doublet model beyond leading order for the low mass region: 1. Renormalisation and constraints

    Shankha Banerjee🇨🇭 · Fawzi Boudjema🇫🇷 · Nabarun Chakrabarty🇮🇳 · Hao Sun🇨🇳

    The present paper is the first in a series that addresses the calculation of the full one-loop corrections of dark matter (DM) annihilation cross-sections in the low mass region of the inert doublet model (IDM). We first review the renormalisation of the model both in a fully on-shell (OS) scheme and a mixed scheme combining on-shell (for the masses) and a $\overline{\mathrm{MS}}$ approach when the partial invisible width is closed and does not allow the use of a full OS scheme. The scale dependence introduced by the mixed scheme is shown to be tracked through an analysis of a parametrisation of the tree-level cross-section and the $\beta$ constant of a specific coupling. We discuss how to minimise the scale dependence. The theoretical uncertainty brought by the scale dependence leads us to introduce a new criterion on the perturbativity of the IDM. This criterion further delimits the allowed parameter space which we investigate carefully by including a host of constraints, both theoretical and experimental, including in particular, new data from the LHC. We come up with a set of benchmark points that cover three different mechanisms for a viable relic density of DM: {\it i)} a dominance of co-annihilation into a fermion pair, { \it ii)} annihilation into 2 vector bosons of which one is off-shell that requires the calculation of a $2\to 3$ process at one-loop, {\it iii)} annihilation that proceeds through the very narrow standard model Higgs resonance. Since the $2\to 3$ vector boson channel features in all three channels and is essentially a build up on the simpler annihilation to OS vector bosons, we study the latter in detail in the present paper. We confirm again that the corrected cross-sections involve a parameter that represents rescattering in the dark sector that a tree-level computation in not sensitive to.

    hep-phhep-exPRD(2021)·26 citations
13. 13*

    Relic density of dark matter in the inert doublet model beyond leading order for the low mass region: 2. Co-annihilation

    Shankha Banerjee🇨🇭 · Fawzi Boudjema🇫🇷 · Nabarun Chakrabarty🇮🇳 · Hao Sun🇨🇳

    We examine the relic density of the light mass dark matter region in the inert doublet model (IDM) when the dominant process is due to co-annihilation between the lightest neutral scalars of the model. The full one-loop electroweak corrections are computed in an on-shell scheme and are found to be well approximated as an effective cross-section expressed in terms of $Z$-observables. The electroweak corrections to the subdominant process which consists of an annihilation into an on-shell $W$ and an off-shell $W$, that is calculated as a annihilation into a 3-body final state, is also performed. The latter reveals an important dependence on a parameter that describes the self-interaction of the new scalars (solely within the dark sector), a parameter which is not accessible in tree-level calculations of standard model (SM)-IDM interactions.

    hep-phhep-exPRD(2021)·19 citations
14. 14*

    Relic density of dark matter in the inert doublet model beyond leading order for the low mass region: 3. Annihilation in 3-body final state

    Shankha Banerjee🇨🇭 · Fawzi Boudjema🇫🇷 · Nabarun Chakrabarty🇮🇳 · Hao Sun🇨🇳

    We perform the first one-loop electroweak corrections for $2\to 3$ processes for dark matter annihilation. These are the dominant processes that enter the computation of the relic density for the low mass region of the inert doublet model (IDM) when annihilations to two on-shell vector bosons are closed. The impact of the one-loop corrections are important as they involve, through rescattering effects, not only a dependence on the parameter controlling the dark sector, not present if a calculation at tree-level is conducted, but also on the renormalisation scale. These combined effects should be taken into account in analyses based on tree-level cross-sections of the relic density calculations, as a theoretical uncertainty which we find to be much larger than the cursory $\pm 10\%$ uncertainty that is routinely assumed, independently of the model parameters.

    hep-phhep-exPRD(2021)·21 citations
15. 15*

    Relic density of dark matter in the inert doublet model beyond leading order for the low mass region: 4. The Higgs resonance region

    Shankha Banerjee🇨🇭 · Fawzi Boudjema🇫🇷 · Nabarun Chakrabarty🇮🇳 · Hao Sun🇨🇳

    One-loop electroweak corrections to the annihilation cross-sections of dark matter in the Higgs resonance region of the inert doublet model (IDM) are investigated. The procedure of how to implement the width of the Higgs in order to regularise the amplitude both at tree-level and at one-loop together with the renormalisation of a key parameter of the model, are thoroughly scrutinised. The discussions go beyond the application to the relic density calculation and also beyond the IDM so that addressing these technical issues can help in a wider context. We look in particular at the dominant channels with the $b\bar{b}$ final state and the more involved 3-body final state, $Wf{\bar{f}}^{\prime }$, where both a resonance and an anti-resonance, due to interference effects, are present. We also discuss how to integrate over such configurations when converting the cross-sections into a calculation of the relic density.

    hep-phhep-exPRD(2021)·24 citations
16. 16*

    $W$-boson production in polarized proton-proton collisions at RHIC through next-to-next-to-leading order in perturbative QCD

    Radja Boughezal🇺🇸 · Hai Tao Li🇺🇸 · Frank Petriello🇺🇸

    We perform a study of $W$-boson production in polarized proton-proton collisions through next-to-next-to-leading order (NNLO) in perturbative QCD. This calculation is required to extend the extraction of polarized parton distribution functions to NNLO accuracy. We present differential distributions at $\sqrt{s}=510$ GeV, relevant for comparison to measurements from the Relativistic Heavy Ion Collider (RHIC). The NNLO QCD corrections significantly reduce the scale dependence of the cross section. We compare the longitudinal single-spin asymmetries as a function of lepton pseudorapidity to RHIC data. The asymmetries exhibit excellent stability under perturbative QCD corrections.

    hep-phhep-exnucl-exPLB(2021)·15 citations
17. 17*

    Forward scattering in a thermal Plasma

    Varun Vaidya🇺🇸

    I examine the regime of forward scattering of an energetic particle in a Plasma medium in thermal equilibrium. Treating the particle as an open quantum system interacting with a bath, I look at the time evolution of the reduced density matrix of the system. The kinematic and dynamical time scales that emerge can exist in several possible hierarchies which can lead to different EFT formulations. I show that in certain hierarchies, it becomes necessary to account for arbitrary number of coherent exchanges between the system and the bath going beyond the independent scattering paradigm. Analytic results are obtained in certain limits and the formalism is applied for the measurement of transverse momentum broadening of a quark in a Quark Gluon Plasma medium.

    hep-phnucl-th7 citations
18. 18*

    Time dependent signatures of core-collapse supernova neutrinos at HALO

    B. Ekinci🇹🇷 · Y. Pehlivan🇹🇷 · Amol V. Patwardhan🇺🇸

    We calculate the response of a lead-based detector, such as the Helium and Lead Observatory (HALO) or its planned upgrade HALO-1kt to a galactic core-collapse supernova. We pay particular attention to the time dependence of the reaction rates. All reaction rates decrease as the neutrino luminosity exponentially drops during the cooling period but the ratio of one-neutron (1n) to two-neutron (2n) event rates in HALO is independent of this overall decrease. Nevertheless, we find that this ratio still changes with time due to the changing character of neutrino flavor transformations with the evolving conditions in the supernova. In the case of inverted hierarchy, this is caused by the fact that the spectral splits become less and less sharp with the decreasing luminosity. In the case of normal hierarchy, it is caused by the passage of the shock wave through the Mikheyev-Smirnov-Wolfenstein resonance region. However, in both cases, we find that the change in the ratio of 1n to 2n event rates is limited to a few percent.

    ↳ astro-ph.HEhep-phnucl-thPRD(2021)·2 citations
19. 19*

    Closer look at white hole remnants

    Aurélien Barrau🇫🇷 · Léonard Ferdinand🇫🇷 · Killian Martineau🇫🇷 · Cyril Renevey🇫🇷

    The idea that, after their evaporation, Planck-mass black holes might tunnel into metastable white holes has recently been intensively studied. Those relics have been considered as a dark matter candidate. We show that the model is severely constrained and underline some possible detection paths. We also investigate, in a more general setting, the way the initial black hole mass spectrum would be distorted by both the bouncing effect and the Hawking evaporation.

    ↳ gr-qcastro-ph.COhep-phPRD(2021)·13 citations
20. 20*

    The Gluon Exchange Model for diffractive and inelastic collisions

    Marek Jeżabek🇵🇱 · Andrzej Rybicki🇵🇱

    We propose a new model for a homogeneous description of hadron-hadron and hadron-nucleus collisions, the Gluon Exchange Model, fundamentally based on color octet (gluon) exchange. In proton-proton collisions we provide an exact description of the final state proton and neutron spectrum including the proton diffractive peak. In proton-nucleus reactions we find that the projectile proton diquark cannot survive in more than about half of multiple proton-nucleon processes and consequently must be very frequently disintegrated, leading to long transfers of baryon number over rapidity space.

    ↳ nucl-thhep-phPLB(2021)·5 citations
21. 21*

    Complex Scalar Field Reheating and Primordial Black Hole production

    Karim Carrion🇲🇽 · Juan Carlos Hidalgo🇲🇽 · Ariadna Montiel🇲🇽 · Luis E. Padilla🇲🇽

    We study perturbations of a complex scalar field during reheating with no self-interaction in the regime $\mu \gg H$, when the scalar field has a fast oscillatory behaviour (close to a pressure-less fluid). We focus on the precise determination of the instability scale and find it differs from that associated with a real scalar field. We further look at the probability that unstable fluctuations form Primordial Black Holes (PBHs) obtaining a significant production of tiny PBHs which quickly evaporate and may subsequently leave a population of Planck-mass relics. We finally impose restrictions on the duration and energy scale of the fast oscillations period by considering that such relics constitute, at most, the totality of dark matter in the Universe.

    ↳ astro-ph.COgr-qchep-phJCAP(2021)·20 citations
22. 22*

    Efficiency corrections for factorial moments and cumulants of overlapping sets of particles

    Volodymyr Vovchenko🇺🇸 · Volker Koch🇺🇸

    In this note we discuss subtleties associated with the efficiency corrections for measurements of off-diagonal cumulants and factorial moments for a situation when one deals with overlapping sets of particles, such as correlations between numbers of protons and positively charged particles. In particular, we discuss the situation commonly encountered in heavy-ion experiments, where first all charges are reconstructed and then protons are selected from these charges by an additional particle identification procedure. We present the efficiency correction formulas for the case when the detection efficiencies follow a binomial distribution.

    ↳ nucl-thhep-phnucl-exNPA(2021)·5 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.