Inclusion Criteria:  Age ≥ 18 and ≤ 75; The ability to give written, informed consent; Fluency in English; Average worst daily pain of at least 4 on a 0 - 10 scale of pain intensity during a typical day. Pain needs to be present for at least 50% of days during a typical week; On a stable pain treatment (pharmacological or otherwise) for the previous four weeks; Diagnosis of chronic low back pain, ongoing for at least 6 months prior to enrollment.  Exclusion Criteria:  Outpatient surgery within 2 weeks and inpatient surgery within 1 month of the time of scanning (this timeframe may be extended if they are not fully recovered from the surgery); Elevated baseline transaminase (ALT and AST) levels above 3 times the Upper Limit of Normal (ULN), accompanied by elevations in bilirubin above 2 times the ULN; Any interventional pain procedures within 6 weeks prior to scanning procedure or at any point during study enrollment; Surgical intervention or introduction/change in opioid regimen at any point during study enrollment; Contraindications to fMRI scanning and PET scanning (including presence of a cardiac pacemaker or pacemaker wires, metallic particles in the body, vascular clips in the head or previous neurosurgery, prosthetic heart valves, claustrophobia); Implanted spinal cord stimulator (SCS) for pain treatment; Any history of neurological illness or major medical illness affecting the central nervous system, unless clearly resolved without long-term consequences; Current or past history of major psychiatric illness (PTSD, depression, and anxiety are exclusion criteria only if the conditions were so severe as to require hospitalization in the past year); Harmful alcohol drinking as indicated by an AUDIT score ≥ 16; Pregnancy or breast feeding; History of head trauma requiring hospitalization; Major cardiac event within the past 10 years; Regular use of recreational drugs in the past 3 months; Any marijuana use, medical or recreational, in the past 2 weeks; An abnormal physical exam (e.g., peripheral edema); Use of immunosuppressive medications, such as prednisone, TNF medications within 2 weeks of the visit; Current bacterial or viral infection likely affecting the central nervous system; Epilepsy or any prescription of an anti-epileptic drug; Use of the medications valproate and clobazam, which may increase risk of hepatic AEs;  Safety concerns related to use of any of the following medications will be discussed on an individualized basis with a physician:  Strong and moderate CYP3A4 inhibitors including boceprevir, cobicistat, conivaptan, danoprevir, elvitegravir, ritonavir, indinavir, itraconazole, ketoconazole, lopinavir, paritaprevir and ombitasvir and/or dasabuvir, posaconazole, saquinavir and telaprevir, tipranavir, clarithromycin, diltiazem, idelalisib, nefazodone, nelfinavir, troleandomycin, voriconazole, aprepitant, cimetidine, ciprofloxacin, clotrimazole, crizotinib, cyclosporine, dronedarone, erythromycin, fluconazole, fluvoxamine, imatinib, tofisopam, disulfiram, and verapamil; Strong and moderate inhibitors of CYP2C19 including fluoxetine and ticlopidine; Sensitive and moderately sensitive substrates of CYP2C19 including clobazam, lansoprazole, omeprazole, S-mephenytoin, and rabeprazole; Sensitive and moderately sensitive substrates of CYP1A2 including alosetron, duloxetine, melatonin, ramelteon, tasimelteon, theophylline, tizanidine, pirfenidone, and ramosetron; Sensitive and moderately sensitive substrates of CYP2B6 including bupropion and efavirenz; Sensitive and moderately sensitive substrates of CYP2C8 including repaglinide, montelukast, pioglitazone, and rosiglitazone; Sensitive and moderately sensitive substrates of CYP2C9 including tolbutamide, celecoxib, glimepiride, and warfarin; Sensitive and moderately sensitive substrates of UGT1A9 including diflunisal, propofol, and fenofibrate; Sensitive and moderately sensitive substrates of UGT2B7 including, gemfibrozil, lamotrigine, and morphine; The following CNS depressants including all antipsychotics, benzodiazepines (except for alprazolam, clonazepam, and lorazepam, which have low binding affinity to TSPO), and non-benzodiazepine sleep aids that have a known reaction with CBD; Use of opioids ≥ 30 mg morphine equivalents on average per month; Actively suicidal, history of suicide attempt or an aborted attempt within the last 5 years, or engagement in non-suicidal self-injurious behavior within the last year; Allergy to sesame oil, and any other ingredients of EPIDIOLEX; Any other contraindications to CBD administration noted by the study physician; Any significant change in drug use and pain treatment from screening visit; In the opinion of the investigators, unable to safely participate in this study and/or provide reliable data (e.g., unable to reliably rate pain; unlikely to remain still during the imaging procedures, etc).